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VOL. 9 NO.?2 DECEMBER 1969

MALACOLOGIA

International Journal of Malacology
Revista Internacional de Malacologia
Journal International de Malacologie
Международный Журнал Малакологии

Internationale Malakologische Zeitschrift

NEW NAMES

catinus (Velutinellus), MARINESCU 1970, p 317
codapavonis (Velurinopsis), MARINESCU 1970, р 315
pilleus (Velutinellus), MARINESCU 1970, p 319
Velutinellus, MARINESCU 1970, p 315

ERRATA, Vol 7, 23

Volume 7, No. 2-3 was unavoidably delayed by the printer; 13 October 1969
is the publication date rather then 31 July 1969 as given on ри.

Oncomelaria hupensis chiui |=Tricula chiui HABE & MIYAZAKI 1962] is a
new name combination, but not a new name as listed on p Vii.

CONTENTS OFIMOE 9

MPEGOKE О. S., DESSAUVAGIE, Т. Е. J. & YOLOYE, V.L. A.
Biology and population dynamics of two sympatric species of Neritina
from Southern Nigeria .

ALVAREZ, J.
Uber die Verbreitung der Land— und Susswasserschnecken in Mittel-
spanien in Bezug auf die verschiedenen Bóden und Gewasser. .

NT; HF.
Zur wúrm-glazialen Überdauerung europäischer Landgastropoden in
Eisrandnáhe. .

AZEVEDO; J. В. de, XAVIER, М. а. L., PEQUITO, M: М. & SIMOES, М.

Contribution to the morphological and biochemical identification of

some strains of the Bulinus truncatus group. .

BACKHUYS, W.
The elevation—effect in Cylindrus obtusus (Drap. 1805). .

Baw NES” ©.
Survival of the embryos of the grey field slug Agriolimax reticulatus
following desiccation of the egg .

BEBBINGTON, A. & THOMPSON, T. E.
Reproduction in Ap/ysia (Gastropoda: Opisthobranchia) .

BERRIE, А.П.
Factors affecting growth and reproduction of freshwater Planorbidae
in East Africa .

BINDER, E.
Cephalic accessory sexual organ of Gymnarion: speciation and
phylogeny (Pulmonata: Helicarionidae). .

BOSS.” K. J.
Systematics of the Vesicomyidae (Mollusca: Bivalvia). .

BOVARD, Р.. FOULQUIER, L.-&*GRAUBY, А.
Etude de la cinetique et de la repartition du Radiocesium chez un
bivalve d'eau douce (Unio requieni Mich.). .

BROWN, 5. С.
The structure and function of the digestive system of the mud snail
Nassarius obsoletus (Say) .

BRUGGEN, A. C. van
Notes on the distribution of terrestrial molluscs in Southern Africa...

BURCH: 7. В. & LINDSAY, С. К.
An immuno—cytological study of the African subgenus Bulinus 3.5...

249

hm
un

254

BURCH, В: & PAT PERSON: С. м
The systematic position of the Athoracophoridae (Gastropoda:
Euthyneura). 251501 gs aon be em Aco Soe о

BUTOF т ТМ. & КОМА. В.
Cytotaxonomic observations in the stylommatophoran family
Helicidae. with considerations on the affinities within the family . . . 261

CHEVALLIER, Н.
Taxonomie et biologie des grands Arion de France (Pulmonata:

Arionidae)r 2. a. ke NES est eke о ee
CEARKE MAMIE

Some aspects of adaptive radiation in recent freshwater molluscs. . . 263
COOMANS, Н. Е.

Biological aspects of mangrove molluscs in the West Indies . . . . . 79

D’ASARO, С. М.
The comparative embryogenesis and early organogenesis of
Bursa corrugata Perry and Distorsio clathrata Lamarck (Gastropoda:
Prosobranchia). ssc 0 G4 ок ee ЕЕ

DUNDEE? DES:
Introduced molluses of the United States © 2 27.2 o re

EEDEN, J. A. van & COMBRINCK, C.
The influence of the substratum on population increase and habitat
selection by Lymnaea natalensis Krs. and Bulinus (B.) tropicus Krs.
(Mollusca: Basommatophora) 5.1.2 - En = 4 2. NS

ETGES, В. 9. & MALDONADO: Т.Е.
The present status of bilharziasis in the Dominican Republic . . . . 40

EOURNIE} J: & CHETAIL, М.
Physiologie de l’organe de perforation de Purpura (Thais) lapillus.
Role de l’anhydrase carbonique : д. о...

СТВОР, А.
Distribution and ecology of Helicodontinae in Northern Italy. . . . 267

GITTENBERGER, E.
Die Gattung Trissexodon Pilsbry о аи

GIUSH Е.
А malacological survey of the small Tuscan Islands . . . . . . . . 85

HADL, G.
Beitrage zur Okologie und Biologie der Pisiden des Lunzer Untersee.. 268

HAEFELFINGER, H. R.
Zur Systematik der Glossodoridier des Mittelmeeres . A AOS

HOHORST, W.
Die Biotope der Leberegelschnecke (Galba truncatula) und ihre
Bedeutung. .

MEAD, A. R.
Aeromonas liquefaciens in the leucodermia syndrome of
Achatina fulica .

MEULEMAN, Е. A.
The ultrastructure of the digestive—gland cells of Biomphalaria
pfeifferi Krs.. an intermediate host of Schistosoma mansoni Sambon. .

IOOSSE, J. & REITZ, D.
Functional anatomical aspects of the ovotestis of Lymnaea stagnalis

(L.).

BIAUTA, В. & BUTOT, L. J.
Contribution to the knowledge of the cytotaxonomic conditions in the
stylommatophoran superfamily Zonitacea.

KNUDSEN, J.
Remarks on the biology of abyssal bivalves .

KRAEMER, L. R.
Flapping behavior in the ae Sn Unionidae):
Some aspects of its neurobiology. ‘ A ae

KROLOPP; E.
Faunengeschichtliche Untersuchungen im Karpatenbecken .

LARYEA, A. A.
The arterial gland of Agriolimax reticulatus (Pulmonata: Limacidae). .

LLOYD. D.C.
Studies on the odour of Oxychilus alliarius (Pulmonata: Zonitidae). .
LUCAS, А.
Remarques sur l'hermaphrodisme juvenile de quelques Veneridae
(Bivalvia). .

MARAZANOF, F.
Contribution a etude ecologique des mollusques des eaux douces et
saumatres de Camargue. .

MARINESCU, F.
Velutinellus, nouveau genre fossile de la familie des Lymnaeidae, et
ses relations avec Velutinopsis et Valenciennius .

MEIER-BROOK, C.
Substrate relations in some Pisidium species (Eulamellibranchiata:
Sphaeriidae). .

101

269

272

111

273

274

МОЕРЫУ. №. Т, ROSS) ТС. & TAMBORES: М.
Problems of Lymnaea truncatula ecology in investigations of
fascioliasis. .

MORRISON, J. P. E.
Zoogeography of hydrobiid cave snails. .

NATARAJAN, R.
Cytological studies of Indian molluscs (Archaeogastropoda:
Neritidae). .

NAWRATIL, O.
Probleme der Massenvermehrung von Helix pomatia L. (Wein-
bergschnecken). .

OBERZELLER, E.
Die Verwandtschafisbeziehungen der Rhodope veranii Köll. zu
den Oncidiiden, Vaginuliden und Rathouisiiden in Bezug auf das
Nervensystem .

MKLAND, J.
Distribution and ecology of the freshwater snails (Gastropoda) of
Norway. .

PAGET, O. E.
Presidential address (Third European Malacological Congress). .

PETITJEAN, M.
Le Strontium dans la coquille des Muricidés (No Abstract received) .

POSTMA, N.
Seven reproducible characteristics of mechanical behaviour in the
snail’s foot musculature (Helix pomatia L.) .

PURCHON, R. D. & BROWN, D.
Phylogenetic interrelationships among families of bivalve molluscs.

RADOMAN, P.
On the taxonomy and biogeography of Hydrobiidae .

RAVERA, O.
Population characteristics of Viviparus ater Christofori and Jan
(Gastropoda: Prosobranchia) from two habitats of Lago Maggiore
(Northern Italy) .

RENZONI, A.
Observations on the tentacles of Vaginulus borellianus Colosi .

RICHARDS ES:
Genetic studies on Biomphalaria glabrata: tentacle and eye variations ..

RICHARDS, C. S.
Genetic studies on Biomphalaria glabrata: mantle pigmentation .

127,

278

279

135

282

153

284

327

339

RUNHAM, N.W.
The use of the scanning electron microscope in the study of the
gastropod radula: The radulae of Agriolimax reticulatus and
Nucellalapillusts И Ey Beige ass ee crc Te)

SALEUDDIN, A. M. S.
Isoenzymes of alkaline phosphatase of Anodonta grandis Say (Bivalvia)

dunimnershellsresemerationts o et BOUL
SALVAT, B.

Dominance biologique de quelques mollusques dans les atolls fermes

KiuamotusBolynesie)r te een jaca A wot es ek) ee NON]

SALVINI-PLAWEN, L. v.
Solenogastres und Caudofoveata (Mollusca: Aculifera): Organisation
une phylogenctische Bedeutung о. OL

SCHALIE, H. van der
American mussel resources in relation to the Japanese pearl industry . 285

SCHALIE, H. van der
The control of schistosome dermatitis in the Great Lakes region
QUESTA een ot Wa aie Saree rath ears celebs me Pe Ain a ee AE er dos OOo

SESHAIYA- В. V.
Some observations on the life-histories of South Indian freshwater

MO A М gr cr о, RS SG
SIEBER, В.

Bebenstormen fossiler BivalVen Ее 285
SOLEM, A.

Phylogenetic ;positionsoicthe Succineidae, о 28

STARMUHLNER, F.

Zur Molluskenfauna des Felslitoral von Rovinj (Istrien). . . . . . . 217
STOHLER, R.

Growth studies on Olivella biplicata (Sow. 1825). . . . . . . . . . 290
STRAUCH, F.

The influence of climate on the adult size of recent and fossil
Hiatella arctica (L.) and its importance for determination of
Е О О СИ О er ee a bay Cn ne DO)

SERUHSAKER, J: W. & COSTLOW, J. D.; №
Some environmental effects on the larval development of
Littorina picta (Mesogastropoda), reared in the laboratory . . . . . 403

TRUEMAN, E. R.
The fluid dynamics of molluscan locomotion. .,........ 243

VOVEEREIT:
Elaboration de la matiére operculaire chez Tricolia pullus (L.)
(Gasteropode: Prosobranche) . .

WAIDHOFER, C.
Anatomische Untersuchungen des Zentralnervensystems von
Fimbria fimbria (Boh.) und Melibe leonina (Gould) (Gastropoda:
Opisthobranchia) поно ое о И

WALDEN, H.
Recent advances in land mollusc research in Sweden .

WARWICK, T.
Systematics of the genus Potamopyrgus (Hydrobiidae) in Europe, and
the causation of the keel in this snail.

WONDRAK., С.
Die Ultrastruktur der Sohlendrüsenzellen von Arion rufus L. .

YOUNG; BD. К.
The functional morphology of the feeding apparatus of some
Indo-West-Pacific dorid nudibranchs

ZAILCH, A:
Report on the General Assembly of Unitas Malaologica Europae .

293

295

297

301

303

421

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MUS. COMP. ZOOL.

LIBRARY

NOVEMBER 1969

JUL 6 1970

HARVARD

UNIVERSITY:

MALACOLOGIA

PROCEEDINGS of the THIRD

EUROPEAN

Vienna

MALACOLOGICAL

1968

CONGRESS

MUS. COMP. ZOOL.
LIBRARY

PROCEEDINGS JUL 6 1970

HARVARD
UNIVERSITY.
of the

Symposium on MOLLUSCS AS PARASITES OR THEIR TRANSMITTERS
and the
THIRD EUROPEAN MALACOLOGICAL CONGRESS

(Vienna, 2-6 September 1968)

Edited by Oliver E. PAGET

Published by the Department of Molluscs of the Natural History Museum,
Vienna, Austria, and the Institute of Malacology,
Ann Arbor, Michigan, U. 5. A.

Vienna, 1969

(Price, US$4 or A.S.100)

ORGANIZING COMMITTEE

Dr. Oliver E. PAGET, President

Dr. C. O. van REGTEREN-ALTENA, Vice-President
Miss Edda OBERZELLER, Secretary

Dr. Oskar NAWRATIL, Treasurer

Dr.h.c. W. KLEMM

Univ.-Prof. Dr. W. KUHNELT
Univ.-Doz. Dr. K. RUSS

Dr. L. SALVINI-PLAWEN
Univ.-Doz. Dr. F. STARMUHLNER

PREFACE

Since the Third European Malacological Congress was tobe held in Vienna,
Austria, exceptional possibilities existed to unite malacologistsfrom Western
and Eastern Europe ina neutral country for scientific lectures and discussions.
Although the advance registration allowed hopes for a great success in this
respect, adverse political circumstances at the very last minute blasted these
expectations. This is especially regrettable because Vienna offers special
suppositions for such an international meeting.

In continuation of the attempt carried out so successfully in Copenhagen, a
two-days’-Symposium preceded the Congress which was dedicated to the topic
“Molluscs as parasites or their transmitters.”

I want to express my warmest thanks to the members of the Organizing
Committee who were of great support in preparing the Congress. The same
goes for all those who have contributed to the success of the arrangements in
one way or another. The willingness of the session Chairmen, who were in-
vited by me to chair the various sessions, was greatly appreciated. The
excursions were excellently guided by the following scientists (in alphabetical
order): Prof. Dr. F. Bachmayer, W. Backhuys, L. Butot, E. Gittenberger,
а. Hadl, W. Klemm, Dr. H. Kollmann and Prof. Dr. W. Kiihnelt.

It is a pleasure for me to thank the Austrian Ministry of Education, the
UNITAS MALACOLOGICA EUROPAEA, and the Society of Friends of the
Natural History Museum for their financial support, which was willingly given
to support the Congress. Especially I want to thank the Director of the Natural
History Museum, Prof. Dr. K. H. Rechinger, who generously offered to me all
the help the Museum could give. Also, I wish to thank Director Dr. E. Becker-
Donner (Museum of Ethnology) and the I.W.K. (Institute for Science and Art)
who put their lecture halls at my disposal.

Sincerest thanks and appreciation are due also to Dr. J. B. Burch and the
editors of MALACOLOGIA, who declared their readiness to publish the Pro-
ceedings of the Congress under most generous conditions as a special volume
of MALACOLOGIA. In doing this, they have taken a very heavy burden off of
the Organizing Committee and have given a most valuable contribution to the
final success of the Congress.

O. E. PAGET
(President)

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CONTENTS

SYMPOSIUM ON MOLLUSCS AS PARASITES OR THEIR TRANSMITTERS
and THIRD EUROPEAN MALACOLOGICAL CONGRESS

Page
EN EN ое реке оао AS EEE ERRE левое Sue CREE canoe eae Zid
ЕО сы се оао о ie ee ое cay wae Sigel do cl о e 1
ое оо ее оо ae еле Se ое ile 3
A A E A E A НЕ V0 ie 4
RASE na AGREE e e 2. a etes am ete, aero LONER D CT de. 9
Report on the General Assembly of UNITAS MALACOLOGICA EUROPAEA .... 17
Symposium on Molluscs as Parasites or their Transmitters
AZEVEDO, J. Е. de, XAVIER, М. 4. L., PEQUITO, М. М. € SIMOES, M.:
Contribution to the morphological and biochemical identification of
some strains of the Bulinus truncatus ото... ...... «mess... do 25
BERRIE, A. D.: Factors affecting growth and reproduction of freshwater
Blainorbidas in Bast AÎTICA ES 2 us egal. ooh ooh оно à de ео а 35
BURCH, J. В. € LINDSAY, G. K.: An immuno-cytological study of the
AITICAN SUOSENUS BULZNUS В. боры Gaus зо оо ое a de so 37
EEDEN, J. А. van & COMBRINCK, C.: The influence of the substratum
on population increase and habitat selection by Lymnaea natalensis Krs.
and Bulinus (B.) tropicus Krs. (Mollusca, Basommatophora)........ nes 39
ETGES, F. J. & MALDONADO, J. F.: The present status of Bilharziasis
LENS Dominican Republic... on tee ot due à ee ounces ie le 0 40
HOHORST, W.: Die Biotope der Leberegelschnecke (Galba truncatula)
UNITÉ li A A ac Dee O оо à ae ce 42
MEAD, A. R.: Aeromonas liquefaciens in the leucodermia syndrome of
ЕЕ TIC LLC CUS sis RA na Dai a) en nie TN Eee Se ee arian о на 43
MEULEMAN, Е. A.: The ultrastructure of the digestive-gland cells of
Biomphalaria pfeifferi Krs., an intermediate host of Schistosoma
MIENSOTERSAMIDONE grat a2 ee пе 43
SCHALIE, H. van der: The control of schistosome dermatitis in the
Great bakes region (coca. nt ccs «a а ое оо 44
Third European Malacological Congress
ADEGOKE, O. S., DESSAUVAGIE, Т. Е. J. € YOLOYE, У. L. A.:
Biology and population dynamics of two sympatric species of Neritina
ОН SOUMET Nipveria,r сое росе ое eu à о он wae 47
ALVAREZ, J.: Uber die Verbreitung der Land- und Stisswasserschnecken
in Mittelspanien in bezug auf die verschiedenen Böden und Gewässer. .... 53
АМТ, H.: Zur würm-glazialen Uberdauerung europäischer Landgastropoden
АО еее са ое а ee Te: ue da neo deals 249
BACKHUYS, W.: The elevation-effect in Cylindrus obtusus (Drap. 1805)..... 251
BEBBINGTON, А. & THOMPSON, T. E.: Reproduction in Aplysia
(Gastropoda, Opisthobranchia). ое ооо ое nn 253
BINDER, E.: Cephalic accessory sexual organ of Gymnarion: speciation
and phylogeny (Pulmonata, Helicarionidae). ...................... 59
BOSS, K. J.: Systematics of the Vesicomyidae (Mollusca, Bivalvia)........ 254

BOVARD, P., FOULQUIER, L. & GRAUBY, A.: Etude de la cinetique
et de la repartition du Radiocesium chez un bivalve d’eau douce

ООО ЕО Mich.) 2:21 P52 A D na 65
BRUGGEN, A. C. van: Notes on the distribution of terrestrial molluscs

IK SOULNCTMVALhICA,;. ¢ lio оо ооо 490

PROC. THIRD EUROP. MALAC. CONGR.
CONTENTS (Continued)

BURCH, J. B. & PATTERSON, C. M.: The systematic position of the
Athoracophoridae (Gastropoda, Euthyneura), ..... 6225...) oe 259

BUTOT, L. J. M. & KIAUTA, B.: Cytotaxonomic observations in the
stylommatophoran family Helicidae, with considerations on the affinities

Within the: fan ly, ...0: sun. era ave este о оо о eae a A 261
CHEVALLIER, H.: Taxonomie et biologie des grands Arion de France

(Pulmonata, Arionidae). Sn US nr Bore whe ee a RER 73
CLARKE, A. H.: Some aspects of adaptive radiation in recent freshwater

MOLIUSCS. о рр ое ео о ne) cope! ey eee A EEE crm qos
COOMANS, H. E.: Biological aspects of mangrove molluscs in the West

ТОВ ао ERA RE око a e A : 79
DUNDEE, D. S.: Introduced molluses of the United States. .... =... 21000100 264
FOURNIE J. & CHETAIL, M.: Physiologie de l’organe de perforation de

Purpura (Thais) lapillus: role de l’anhydrase carbonique............. 265
СТВОР, A.: Distribution and ecology of Helicodontinae in Northern Italy. ... 267
GITTENBERGER, E.: Die Gattung Trissexodon Pilsbry........... O
GIUSTI, F.: A malacological survey of the small Tuscan Islands. ......... 85
HADL, G.: Beitráge zur Okologie und Biologie der Pisidien des Lunzer

A ERE O oo ao 268
HAEFELFINGER, HR.: Zur Systematik der Glossodoridinae des

Mittelmeeres:........% лора зе CE ER a 93
JOOSSE, J. € REITZ, D.: Functional anatomical aspects of the ovotestis

Of Lymnaea stagnalis (L.). naaa ds eee 101

KIAUTA, B. & BUTOT, L. J.: Contribution to the knowledge of the
cytotaxonomic conditions in the stylommatophoran superfamily

ZONILACEA. arm rene een BES is Ok EEE 269
KNUDSEN, J.: Remarks on the biology of abyssal bivalves.......... ео
KRAEMER, Г. R.: Flapping behavior in the Lampsilinae (Pelecypoda,

Unionidae): Some aspects of its neurobiology. ..................... 272
KROLOPP, E.: Faunengeschichtliche Untersuchungen im Karpatenbecken.... 111
LARYEA, A. А.: The arterial gland of Agriolimax reticulatus

(Pulmonata; Tima cidae) ао a Е malo
LLOYD, D. C.: Studies on the odour of Oxychilus alliarius

(Pulmonata, Zonitidae). . a... ls ua ra A 274
LUCAS, A.: Remarques sur 1'hermaphrodisme juvenile de quelques

Vieneridae (Bivalvia) on. cist aie swe A 215
MARAZANOF, F.: Contribution а l’etude ecologique des mollusques

des eaux douces et saumatres de Camargue... 5 2 eno ro bee 277
MEIER-BROOK, C.: Substrate relations in some Pisidium species

(Eulamellibranchiata, Sphaerlidae). о: к are a а Pe |
MORPHY, М. J., ROSS, J. а. & TAYLOR, 5. M.: Problems of Lymnaea

truncatula ecology in investigations of fascioliasis............. ро 7}
MORRISON, J. P. E.: Zoogeography of hydrobiid cave snails............ 278
NATARAJAN, R.: Cytological studies of Indian molluscs

(Archaeogastropoda: Neritidae)... . и еле оо ee 279
NAWRATIL, O.: Probleme der Massenvermehrung von Helix pomatia L.

(Weinbergschnecken)... ... re... a le a по р ee AS Us 15,

OBERZELLER, E.: Die Verwandtschaftsbeziehungen der Rhodope veranii
Koll. zu den Oncidiidae, Vaginulidae und Rathouisiidae in bezug auf das
Nervensystem... its se a hla: ооо enter a 282

PROC. THIRD EUROP. MALAC. CONGR.
CONTENTS (Continued)

OKLAND, J.: Distribution and ecology of the freshwater snails

Kaastropoda)l ов ea 1143
PETITJEAN, M.: Le Strontium dans la coquille des Muricidés

[no abstract received]
POSTMA, N.: Seven reproducible characteristics of mechanical behaviour

inthe snall’s foot musculature (Heli ротана1.. 4. Are ое. 153
PURCHON, R. D. & BROWN, D.: Phylogenetic interrelationships among

PML SOF DEV ALVIC. оные an xo tai ese vou Bla ee ane ное ня 163
RADOMAN, P.: Оп the taxonomy and biogeography of Hydrobiidae. ........ 173

RAVERA, O.: Population characteristics of Viviparus ater Christofori
& Jan (Gastropoda, Prosobranchia) from two habitats of Lago Maggiore

CNOTERO RNY tal me). ias ee ad Verá tds 2 à ... 284
RENZONI, A.: Observations on the tentacles of Vaginulus borellianus
COS A DES E NAAA re li Po tere 284

RUNHAM, N. W.: The use of the scanning electron microscope in the
study of the gastropod radula: The radulae of Agriolimax reticulatus

AIN CO Sa DIS: os A A e tele oe’, à e 179
SALVAT, B.: Dominance biologique de quelques mollusques dans les

atolls fermes (Tuamotu, Polynesie). ........0...co.oooooooo.. à ou 187
SALVINI-PLAWEN, L. v.: Solenogastres und Caudofoveata (Mollusca,

Aculifera): Organisation und phylogenetische Bedeutung.............. 191
SCHALIE, H. van der: American mussel resources in relation to the

Е ДЕЯ Industry. Mme Min: Gus Bea Ye mnt и 285
SESHAIYA, R. V.: Some observations on the life-histories of South

MAN TES Виа еее MUSSOLS aa lens Ailes mess à Me a dare Sees 286
SIEBER; R:: Lebensformen fossiler Bivalven. .…...... u... 4244. 4,4% 288
SOLEM, A.: Phylogenetic position of the Succineidae. .............,,.. 289
STARMUHLNER, F.: Zur Molluskenfauna des Felslitorals von Rovinj

(SEC MR BI ee A ie ee ZN
STOHLER, R.: Growth studies on Olivella biplicata (Sow. 1825)........... 290

STRAUCH, F.: The influence of climate on the adult size of recent and
fossil Hiatella arctica (L.) and its importance for determination of

pare 0 temperature: ео hots ооо eco D ere ee 291
TRUEMAN, Е. R.: The fluid dynamics of molluscan locomotion........... 243
VOVELLE, J.: Elaboration de la matiére operculaire chez Tricolia

pulsa.) (Gastropoda, Prosobranchia)... . ее ar ce aan WE 293

WAIDHOFER, Ch.: Anatomische Untersuchungen des Zentralnerven-
systems von Fimbria fimbria (Boh.) und Melibe leonina (Gould)

(Gastropoda, Opisthobräanchia): „4, kan is Gy Sod so od Gerd he ES 295
WALDEN, H.: Recent advances in land mollusc research in Sweden. ....... 297
WARWICK, T.: Systematics of the genus Potamopyrgus (Hydrobiidae)

in Europe, and the causation of the keel in this snail................. 301
WONDRAK, G.: Die Ultrastruktur der Sohlendrtisenzellen von

LON US Sur. 2. De aa ae e BCR WI a Bow ia A 303

ISO HATEICIDaNES a cs. dd рано A A A ees 307

TU A à à Da su NO 313

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PROC. THIRD EUROP. MALAC. CONGR.

INTRODUCTION

The Third European Malacological Congress took place in Vienna, Austria,
at the Museum of Natural History, from September 4th to 6th, 1969. The
Congress was preceded by a Symposium on September 2nd to 3rd with the
topic: “Molluscs as parasites or their transmitters.”

The General Assembly of UNITAS MALACOLOGICA EUROPAEA was held
on September 6th at the Natural History Museum.

The Symposium was welcomed by Dr. Oliver E. Paget, President of the
Congress and of UNITAS MALACOLOGICA EUROPAEA. At the opening
session, Dr. Paget had the pleasure to welcome not only 155 participants from
27 countries (9 of which are outside Europe), but also as guests of honour his
excellency, the Minister of Education, Dr. Th. Piffl-Percevic, and the Director
of the Natural History Museum, Prof. Dr. K.H. Rechinger, both of whom also
gave addresses of welcome. The Minister expressedthe special interest both
he and the Ministry had in the Congress and its results. He assured the
Congress that the further development of the Department of Molluscs of the
Natural History Museum would be taken into sympathetic consideration and
support. After the opening of the Congress, the Minister, the Director and
the participants visited the new exhibition on Molluscs at the Museum.

During the Congress, four excursions were undertaken to Rax, Bad Fischau
and Bad Vóslau, Vösendorf, and to Mödling.

On the first day, September 4th, all the participants of the Congress were
invited by Bruno Marek, Гога Mayor, to the Vienna Town Hall. Next day
there was a reception at the NaturalHistory Museum, given by the Organizing
Committee, the Directory of the Natural History Museum, and the Society of
Friends of the Natural History Museum. At both occasions the members of
the Congress used the opportunity to renew old friendships and connections,
and to make new ones.

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PROC. THIRD EUROP. MALAC. CONGR.
PROGRAM

SYMPOSIUM ON MOLLUSCS AS PARASITES OR THEIR TRANSMITTERS

September 2nd Chairman: H. Hohorst
Morning Session

BURCH, J. B.: An immuno-cytological study of the African subgenus
Bulinus S.S.

ETGES, F. J.: The present status of bilharziasisinthe Dominian Republic.

MEULEMAN, F. A.: The ultrastructure of the digestive gland-cells of
Biomphalaria pfeifferi, an intermediate host of Schistosoma mansoni.

September 2nd Chairman: J. B. Burch

Afternoon Session

SCHALIE, v. d.: The control of schistosoma dermatitis in the Great Lakes
Region (U. S. A.).

AZEVEDO, J. Fraga de: Classification of Туетаюаа vector snails by
biochemical methods and its importance.

MEAD, A.: Aeromonas liquefaciens in the leucodermia syndrome of
Achatina fulica.

September 3rd Chairman: J. А. у. Eeden

Morning Session

HOHORST, W.: Biotope der Leberegelschnecke Galba truncatula und ihre
Besiedlung.

BERRIE, A. D.: Factors effecting growth and reproduction of freshwater
Planorbidae in East Africa.

EEDEN, J. B. v.: Aspects of the substratum as a factor in the biology of
Lymnaea natalensis Krauss and Bulinus tropicalis Krauss.

THIRD EUROPEAN MALACOLOGICAL CONGRESS
Sections A+B: Systematics, Faunistics, Physiology, Genetics
Sections C + D: Ecology, Zoogeography, Anatomy, Biogeny

September 4th Chairman: Н. Lemche Section A+B
Afternoon Session

SALVINI-PLAWEN, L. v.: Solenogastres und Caudofoveata- ihre Organisa-
tion und phylogenetische Bedeutung.

PURCHON, В. D.: Phylogenetic interrelationships among families of bivalve
molluscs.

RADOMAN, P.: Taxonomie der Hydrobiidae.

ALVAREZ, J.: Eine neue Methode zur Präparation von Siisswasser-
conchylien.

STARMUHLNER, F.: Neu-Kaledonien (invited lecture).

(3)

PROC. THIRD EUROP. MALAC. CONGR.
PROGRAM (Continued)

September 4th Chairman: H. Janus Section С + D
Afternoon Session

ALVAREZ, J.: Uber die Verbreitung von Land- und Stisswasserschnecken
in Mittelspanien in bezug auf Böden und Gewässer.

АМТ, H.: Zur würm-glazialen Überdauerung europäischer Landgastropoden
in Eisrandnähe.

ÖKLAND, J.: Distribution and ecology of the freshwatersnails of Norway.

CLARKE, A.: Adaptive radiation in North American freshwater molluscs.

September 5th Chairman: Е. Starmühlner Section A+B
Morning Session

BOSS, K.: Deep-sea bivalves, the genus Vesicomya and its relatives.
SOLEM, A.: Phylogenetic position of the Succinaeidae.

GIUSTI, F.: A malacological survey of the Tuscan Little Islands.
GITTENBERGER, E.: Die Gattung Trissexodon.

September 5th Chairman: Fraga deAzevedo SectionA+B
Morning Session

BACKHUYS, W.: Der Elevationseffekt bei Cylindrus obtusus Drap.

BUTOT, L.: Cytotaxonomic observations in the stylommatophoran family
Helicidae.

KROLOPP, E.: Faunengenetische Untersuchungenim Karpatenbecken.

STRAUCH, F.: Klimaabhängiges Gróssenwachstum bei Hiatella arctica.

BEBBINGTON, A.: Reproduction in Aplysia.

September 5th Chairman: В. Salvat Section C + D

Morning Session

BINDER, E.: Cephalic accessory sexualorgan of Gymnarion-speciation and
phylogeny.

GIUSTI, F.: The fine structure of the alimentary canal in Mytilus gallo-
provincialis Lam.

RENZONI, A.: Observations on the tentacles of gastropods.

JOOSSE, J.: Anatomy and function of the reproductive system of Lymnaea
stagnalis.

KIAUTA, В. (read by Butot): Contribution to the knowledge of the cytological
conditions in the stylommatophoran family Vitrinidae.

LARYEA, A.: The arterial gland of Agriolimax reticulatus.

LUCAS, A.: Remarques sur l’hermaphrodisme juvenile de quelques
Veneridae (Bivalves).

September 5th Chairman: О; E. Paget Section A+B

Afternoon Session

POSTMA, N.: Uber das mechanische Verhalten der Muskulatur des
Schneckenfusses.
LLOYD, D.: The odour of Oxychilus alliarius.

PROC. THIRD EUROP. MALAC. CONGR.
PROGRAM (Continued)
FOULQUIER, L.: Etude de la cinetique et de la repartition du radiocesium
chez un bivalve d’eau douce.
KRAEMER, L. R.: Flapping behavior in the Lampsilinae (Pelecypoda,
Unionidae): some aspects of its neurobiology.

PEAKE, J.: Solomon- Islands (invited lecture).

September 5th Chairman: В. Schlickum Section С + D

Afternoon Session

KNUDSEN, J.: Remarks on the biology of abyssal bivalves.
MEIER-BROOK, C.: Substrate relations in some Pisidium-species.
SIEBER, R.: Okologie und Lebensformen fossiler Bivalven.

September 5th Chairman: F. Starmtihlner Section C + D

Afternoon Session

OBERZELLER, E.: Verwandtschaftsbeziehungen der Rhodope veranyi zu
den Soleolifera in bezug auf das Nervensystem.

WAIDHOFER, Chr.: Vergleichende Untersuchungen tiber das Nervensystem
von Fimbria fimbria und Melibe leonina (Opisthobranchia).

VOVELLE, J.: Elaboration des materiaux operculaire chez Prosobranches.

WONDRAK, G.: Das elektronenoptische Bild des Sekretionsablaufes in
Sohlendrtisenzellen von Avion rufus.

HADL, G.: Anatomische Merkmale bei einigen Pisidium-Arten und der
Einfluss des Parasitismus.

RUNHAM, N.: Scanning electron microscope studies on the mollusc radula.

September 6th Chairman: L. Salvini-Plawen Section A +B
Morning Session

PETITJEAN, M.: Le strontium dans la coquille des Muricidae.

TRUEMAN, E.: The fluid dynamics of molluscs.

FOURNIE, J. & CHETAIL, M.: Roledel’anhydrase carbonique dans l’organe
de perforation de Purpura (Thais) lapillus.

RAVERA, O.: Population characteristics of Viviparus ater settled in two
habitats of a subalpine lake- Lago Maggiore.

STARMUHLNER, F.: Die Molluskenfauna des Felslitorals der Nordadria.

HAEFELFINGER, HR.: Die Glossodoridier des Mittelmeers.

September 6th Chairman: N. Postma Section С + D
Morning Session

BRUGGEN, A.: On the distribution of terrestrial molluscs in Southern
Africa.

CHEVALLIER, H.: Biologie des Limaciens du genre Avion en France.

DUNDEE, D.: Introduced molluscs of the United States.

GIROD, A.: La distribution du genre Helicodonta dans le Nord de 1'Italie.

NAWRATIL, O.: Biologie und Zucht der WeinbergschneckeHelix pomatia L.

MORPHY, M. J.: Problems of Lymnaea truncatula ecology ininvestigations
of fascioliasis.

PROC. THIRD EUROP. MALAC. CONGR.
PROGRAM (Continued)
STOHLER, R.: Growth studies on Olivella biplicata.

September 6th Chairman: F. Toffoletto Section A+B

Afternoon Session

WARWICK, T.: Systematics and shell ornamentation in the prosobranch
Potamopyrgus in Europe.

COOMANS, H.: Biological aspects of mangroove molluscs inthe West Indies.

BURCH, J. B.: The systematic position of the Athoracophoridae.

ANGELETTI, S.: My new book on shells.

September 6th Chairman: S. P. Dance Section C + D

Afternoon Session

SALVAT, B.: Dominance biologique de quelques especes de mollusques dans
les atolls fermes (Archipel des Tuamotu, Polynesia).

SCHALIE, H. v. d.: American mussel resources inrelationto the Japanese
pearl industry.

MARAZANOFF, F.: Contribution à l’étude écologique des mollusques des
eaux douces et saumatres de Camargue.

MORRISON, J.: Zoogeography of hydrobiid cave-snails.

WALDÉN, H.: Recent advances in landmollusc-research in Scandinavia.

PROC. THIRD EUROP. MALAC. CONGR.

EXCURSIONS

The Rax-alp (September 3rd)

Two groups, guided by E. Gittenberger and W. Backhuys.

Vienna woods, Klosterneuburg - Ladies’ program (September 4th)

A whole-day excursion toured the monastery and famous Altar of Verdun.

Mödling (September 5th)

Two groups guided by W. Klemm and L. Butot.

City tour - Ladies’ program (September 5th)

Fischau (September 6th)

Two groups guided by W. Kthnelt and G. Hadl.

Leopoldsdorf (September 6th)

A paleontological excursion guided by Е. Bachmayer and H. Kollmann.

Porcelain manufacture - Ladies’ program (September 6th)

Museum of Fine Arts, Imperial Treasure, “Heurigen” (September 7th)

Tour of Austria, 4 days (departed September 8th)

(7)

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MALACOLOGIA, 1969, 9(1): 9-15
PROC. THIRD EUROP. MALAC. CONGR.
PRESIDENTIAL ADDRESS
Ladies and gentlemen!

I am fully aware of the fact that English, without doubt, is the language
understood by most of all attending this Congress. Nevertheless, I ask for
your understanding when giving my Presidential Addressin German. German
is the language of this country, and Germanis also one of the official languages
of the European Malacological Congresses. Therefore, Ihope you will under -
stand my choosing German for this Address. Thank you!

Meine sehr geehrten Damen und Herren!

Ich glaube, diese kleine Einleitung jenen Kollegen schuldig gewesen zu sein,
die die deutsche Sprache nicht vollstandig beherrschen.

Auf diesem Kongress wird so viel und so ausfúhrlich in den einzelnen
Sektionen über malakologische Fragen gesprochen, dassich mich entschlossen
habe, insoferne aus dem Rahmen zu fallen, als ich kein fachliches Thema
gewählt habe, sondern einige Probleme behandeln möchte, die sich mir im
Zusammenhang mit diesem Kongress und vor alleminbezug auf das Aufgaben-
gebiet der UNITAS und ihreinternationale Zusammenarbeit aufgedrängt haben.
Die UNITAS MALACOLOGICA EUROPAEA ist eine sehr junge Organisation
und daher noch manchmal mit einigen Kinderkrankheiten behaftet. Viele und
wichtige Aufgaben sind für diese Organisation vorgesehen. In erster Linie ist
es die internationale jedoch auf Europa beschränkte Zusammen arbeit. Leider
habe ich den Eindruck, dass sie bisher nur im Rahmen der üblichen und aus-
gezeichnet funktionierenden kollegialen Kontakte geblieben ist. Vielleicht
werden Sie sich wundern, dass ich als derzeitiger Präsident der UNITAS an
dieser eigenen Organisation Kritik übe. Ich möchte aber sagen, dass mir
gerade deshalb ihr Gedeihen und ihre Zukunft und darüber hinaus ihre
Schwächen besonders am Herzen liegen. Die Zeit meiner Präsidentschaft
für diesen Kongress ist nur mehr auf wenige Tage beschränkt. Das gleiche
gilt für die Präsidentschaft bei der UNITAS. Ich möchte daher diese Gelegen-
heit nicht vorübergehen lassen, ohne an Sie den Appell zu richten, durch Ihren
Beitritt zu dieser Organisation jene Ziele zu unterstützen, die sie sich
gestellt hat.

Ziele, die zweifellos im Interesse eines jeden einzelnen liegen und die nur
erreicht werden können, wenn wir wirklich alle zusammenarbeiten. Hauptziel
der UNITAS ist es, den europäischen Malakologen eine Dachorganisation zu
geben, unter deren Auspizien die regelmässige Abhaltung von Kongressen
gewährleistet wird. Während der übrigen 3 Jahre wird sie aber den Erwar-
tungen nicht immer gerecht, die wir in sie gesetzt haben. Durch den regel-
mässigen Wechsel in der Präsidentschaft werden alle jene Projekte, die der
jeweilige Präsident im Auge hat, die ihm besonders am Herzen liegen, nur
kurz angeschnitten und fallen spätestens nach 3 Jahren wieder der Verges-
senheit anheim. Meine Pläne lassen sich daher kurz in dem Satz zusammen-
fassen: Aktivierung der UNITAS durch Eigeninitiative, durch die Schaffung
permanenter Komitees und die Koordinierung bestimmter Arbeiten. Unter
Aktivierung der UNITAS verstehe ich nicht nur eine gewisse Reorganisation

(9)

PROC. THIRD EUROP. MALAC. CONGR.

in ihren Aufgaben, sondern diese Aktivierung muss in erster Linie von ihren
Mitgliedern ausgehen. Um Ihnen deutlicher zu machen, was ich darunter
verstehe, möchte ich nur eine einzige Tatsache anführen: Sowohl für diesen
Kongress, als auch für den kommenden im Jahr 1971 mussten die Vorschläge
für den Tagungsort wie auch für das Komitee und den Präsidenten vom
Vorstand der UNITAS ausgehen, um den Anforderungen der Satzungen zu
entsprechen. Von keiner anderen Seite und von keiner Gruppe von Einzel-
mitgliedern wurden Vorschläge eingereicht, die den Satzungen entsprachen.
Ich weiss nun nicht, ob man diese Inaktivität einer gewissen Gleichgültigkeit
der Mitglieder anlasten soll, oder nur dem übergrossen Vertrauen, das man
in die Beschlüsse des Vorstandes setzt, dem man derartige Entscheidungen
zur Gänze überlässt. So schmeichelhaft das einerseits wäre, so glaube ich
doch, dass es sehr zu begrüssen ist, wenn durch ein regeres Interesse der
Mitglieder jeweils mehrere Vorschläge zur Wahl des nächsten Präsidenten-
teams als auch zur Wahl des neuen Tagungsortes vorliegen würden. Nicht
nur die Auswahlmöglichkeiten wären grösser, sondern das Wesentliche daran
ist, dass wir uns alle (und ich möchte mich dabei durchaus nicht aus-
schliessen), verantwortlich fühlen für das Geschick dieser von uns selbst ge-
schaffenen Organisation, an der wir entweder als Mitglieder beteiligt oder
in anderer Weise interessiert sind.

Ich möchte Ihnen aber darüber hinaus nun einige Vorschläge unterbreiten,
die dieser Aktivität auch in anderer Richtung dienen sollen und möchte damit
meinen Beitrag dazu leisten, die UNITAS zu einer lebendigen und aktiven
Organisation zu gestalten.

Jeder, der einmal mit den Vorbereitungsarbeiten für Kongresse oder eine
Tagung zu tun hatte, weiss, wieviel Arbeit dahintersteckt, die mit dem Ende
des Kongresses meist nutzlos geworden ist. Die erste Hauptarbeit bei der
Vorbereitung dieses Kongresses war es, allein Fragekommenden Malakologen
zu erfassen. Das Adressenmaterial, das ich im Laufe meiner Vorarbeiten
für diesen Kongress zusammengetragen habe, umfasst annähernd 2.000
Adressen. In dieser Zahl sind alle Malakologen enthalten, deren ich habhaft
werden konnte. Zweifellos fehlt noch ein beträchtlicher Teil. Aber es ist
immerhin eine gute Ausgangsbasis und eine so grosse Zahl von Malakologen
mit Adresse und Arbeitsgebiet zur Verfügung zu haben, wäre sicherlich für
jeden von uns interessant, ist aber in den wenigsten Fällen wirklich zugäng-
lich. Die Auswahl der erfassten Malakologen erfolgte nach den Mitglieder-
listen der diversen malakologischen Gesellschaften, nach den Teilnehmer-
listen der bisherigen Kongresse, sowie nach den Autoren malakologischer
Arbeiten der letzten lo Jahre in sämtlichen mir zur Verfügung stehenden
malakologischen Zeitschriften. Diese Adressen werden natürlich fortlaufend
ergänzt und dadurch die Liste erweitert. Nach der restlosen oder fast rest-
losen Erfassung aller Malakologen wäre es daran gelegen, die einzelnen
Arbeitsgebiete durch die publizierten Arbeiten näher zu umreissen. Das
würde zwar für jeden von Ihnen und für jeden, der dabei erfasst wird,
zweifellos eine gewisse Arbeitsbelastung bedeuten. Ich bin aber davon über-
zeugt, dass sich jeder gerne dieser Aufgabe unterziehen wird im Hinblick
auf den grossen Vorteil, den er dann daraus ziehen kann. Ich möchte nun in
diesem Zusammenhang nicht den Eindruck erwecken, dass ich lediglich mit
guten Ratschlägen vorangehe, deren Durchführung ich dann anderen über-
lasse. Es geht nämlich nicht so sehr um das Finden neuer Probleme (davon
gibt es zweifellos genug), sondern in erster Linie um deren Durchführung.
Ich möchte daher vor diesem Forum eine Feststellung treffen, die meinen

PAGET: PRESIDENTIAL ADDRESS

Vorschlägen einen realen Hintergrund gibt. Ich stelle die Ergebnisse meiner
bisherigen Vorbereitungsarbeiten zur Erfassung aller Malakologen vollständig
zur Verfügung. Ich bin darüber hinaus bereit, diese Arbeit fortzusetzen
und damit allen Kollegen zugänglich zu machen. Es ist selbstverständlich,
dass ich diese Arbeit nur mit Ihrer Mithilfe und der der übrigen Malakologen
durchführen kann. Wesentlich wäre jedoch, dass mir die Generalversammlung
der UNITAS diese Aufgabe offiziell überträgt.

Die Museen stellen zweifellos die Zentralstellen der allgemeinen Zusammen-
arbeit und die Keimzellen der malakologischen Forschung dar und damit
zusammenhängend kann die Rolle der Museumkustoden gar nicht hoch genug
eingeschätzt werden. Sie verwalten ausserordentlich wertvolle, umfangreiche
und häufig auch historisch unschätzbare Sammlungen, die die Grundlagen
der meisten Arbeiten darstellen oder aber für die Durchführung einer Arbeit
durch die Fülle des vorhandenen Vergleichsmaterials von grösster Bedeutung
sind. Ich möchte daher den Vorschlag machen, bei allen künftigen Kongressen
jeweils einen Tag im Anschluss an die Übrigen Beratungen für Besprechungen
der Museumskustoden vorzusehen und für Fragen, die ausschliesslich die
Museumsarbeiten betreffen. Leider war es für diesen Kongress noch nicht
möglich, diesen Plan durchzuführen, ich wäre jedoch glücklich, wenn diese
Anregung für die Zukunft aufgenommen würde.

Eine weitere Frage, die mir sehr am Herzen liegt und sicherlich auch
manchem anderen, ist die Erfassung der jeweils neuesten Literatur. Das
Studium der einschlägigen Literatur ist oft ausserordentlich zeitraubend und
vielen Wissenschaftlern ist sie nicht immer in ausreichendem Mass zugäng-
lich. Wenngleich an den meisten grossen Museendie entsprechende Literatur
aufliegt, so gibt es doch zahlreiche kleinere Aufsätze, die nicht in malakolo-
gischen Zeitschriften publiziert werden und damit oft der Aufmerksamkeit
entgehen. Die derzeitigen Zusammenfassungen erscheinen meist erst sehr
spät und sind vor allem nicht jedem zugänglich. Im allgemeinen verfügen
auch nur Museen und manche Institute darüber. Ich halte es daher für zweck-
mässig, eine Zentralstelle zu schaffen, die die Titelder gesamten publizierten
malakologischen Literatur eines Jahres aus Europa sammelt und am Ende
des jeweiligen Jahres hektographiert an die Interessenten versendet. Die
Hauptfrage ist auch hier, wer sich dieser Aufgabe unterziehen soll. Auch in
diesem Fall bin ich bereit, mich dieser sicherlich nicht kleinen Aufgabe zu
widmen. Voraussetzung dafür wäre allerdings Ihre Mitarbeit und die Zusen-
dung jeweils eines Separatums an die Molluskensammlung des Naturhisto-
rischen Museums in Wien. Sie werden nun vielleicht mit Recht der Ansicht
sein, dass es sich dabei um eine sehr geschickte Methode handelt, meine
Sammlungsbibliothek aufzuwerten und zu vergrössern. Dasist zweifellos rich-
tig. Ich glaube aber, dass es trotzdem nur ein bescheidener Ausgleich wäre
für die damit verbundene und sicherlich nicht geringe Arbeit. Vor allem aber
ist es eine conditio sine qua non, denn ohne Ihre Mitarbeit ist dieser Plan
von vornherein zum Scheitern verurteilt. Ausserdem wird diese Liste der
eingelaufenen Separata jährlich an die Interessenten versendet, sodass nicht
nur die “Bereicherung” der Sammlungsbibliothek im Vordergrund steht,
sondern die Tatsache der besseren und schnelleren Information der Kollegen.
Wenn auch einige der hier vorgebrachten und angeschnittenen Ideen bereits bei
anderen Anlässen angedeutet oder angeregt wurden, so Kann ich mich des
Eindrucks nicht erwehren, dass es in fast allen bisherigen Fällen eben nur
bei den Vorschlägen geblieben ist, weil die Durchführung der Arbeiten von
niemandem übernommen werden wollte.

PROC. THIRD EUROP. MALAC. CONGR.

Die Tatsache jedoch, dass ich mich bereit erkláre, diese Aufgaben selbst
zu Ubernehmen, enthebt Sie, meine Damen und Herren, der unangenehmen
Belastung, ein Opfer dafür ausfindig zu machen. Ich möchte aber auch in
diesem Fall vorschlagen, diese meine Anregungeninder Generalversammlung
kurz zu diskutieren und durch Ihre Zustimmung ihr den Charakter einer
offiziellen Beauftragung zu geben. Es würde mir damit sicherlich leichter
gemacht werden, für diese Aufgabe nicht nur die Unterstützung der UNITAS,
sondern auch die der offiziellen Stellen des österreichischen Unterrichts-
ministeriums zu erreichen. Wie Sie gehört haben, hat der Herr Bundes-
minister für Unterricht heute vormittag recht weitgehende Zusicherungen und
Versprechungen gemacht, die mich hoffen lassen, dass in Zukunft die Belange
der Mollusken-Sammlung des Naturhistorischen Museums in Wien von
offizieller Stelle aus grössere Beachtung und Unterstützung finden werden.

Eine weitere, meiner Meinung nach sehr wesentliche Frage ist jene der
Erfassung der wissenschaftlichen Sammlungen, seien sie nun Museums-,
Instituts- oder Privatsammlungen. Mr. Dance hat in seinem Buch “Shell
Collecting” in dieser Richtung einen ganz wesentlichen Beitrag geleistet,
indem er die historisch wichtigen Sammlungen zusammengefasst hat. Es
liegen bekanntlich auch von einigen Museen und Institutionen Publikationen
vor, die eine Zusammenfassung der in ihnen enthaltenen Sammlungen bringen.
Die Erfassung der historischen Sammlungen ist zweifellos von grossem Wert
im Zusammenhang mit jenen Arbeiten, deren Grundlage sie darstellen. Ich
bin aber der Ansicht, dass eine solche Zusammenfassung sich nicht nur auf
jenes Material stützen sollte, das ein Mindestalter von loo Jahren aufweisen
muss, um in die Reihe dieser Auserwählten aufgenommen zu werden. Durch
die Erfassung auch jüngerer Sammlungen und die möglichst genaue Be-
schreibung ihres Inhalts würde zahlreichen Kollegen die Möglichkeit gegeben
werden, das für ihre Arbeiten notwendige Material ungeheuer zu erweitern
und damit ihre Ergebnisse auf eine wesentlich breitere Basis stellen zu
können. Bei der Abfassung von Monographien, bei vergleichenden Unter-
suchungen und Ahnlichem, kann das untersuchte Material nicht umfangreich
genug sein. Und selbst in den Museen steht es nicht immer in ausreichendem
Ausmass zur Verfügung. Durch eine möglichst umfangreiche und lückenlose
Erfassung auch kleinerer Sammlungen bietet sich jedoch die Möglichkeit,
über ein ungleich grösseres Reservoir zu verfügen. Material, das infolge
seines relativ geringen Ausmasses niemals Grundlage für eine umfassende
Arbeit sein könnte und damit brachläge, könnte damit der Vergessenheit und
der Unbedeutendheit entrissen werden und alskleinesSteinchen eines Mosaiks
wertvolle Dienste leisten können. Und wenn wir alle, wie ich hoffe, uns zum
Grundsatz der gemeinsamen Zusammenarbeit bekennen (und das tun wir
sicherlich, sonst hätten wir uns nicht zudiesem Kongress zusammengefunden),
dann darf es dabei keine Bedenken selbstsüchtiger oder kleinlicher Art geben,
die ein solches Vorhaben verhindern könnten. Mein Versuch, auch kleinere
Sammlungen zu erfassen, hat recht gute Ergebnisse gebracht. Ich möchte
auch an dieser Stelle all jenen danken, die der Aufforderung, an dieser Liste
mitzuarbeiten, Folge geleistet haben. Diese Liste ist das Ergebnis meiner
ersten versuchsweisen Umfrage und ich hoffe, dass eine Vervollständigung
und ein weiterer Ausbau auch fernerhin Ihre Unterstützung finden wird, um
nach und nach eine wirklich wertvolle Arbeitsunterlage damit zu erreichen.

Eine besondere Schwierigkeit stellen die Faunenlisten der einzelnen Länder
dar. Wenngleich gute Ansätze vorliegen und für eine Reihe von Ländern
bereits derartiges vorhanden ist, so bleibt noch sehr viel zu tun übrig, um

PAGET: PRESIDENTIAL ADDRESS

eine Fauna Malacologica Europaea zuerreichen. ES ware äusserst verdienst-
voll, wenn sich in jedem europäischen Land ein Museumskustos oder interes-
sierter Malakologe fánde, der diese zwar ausserordentlich zeitraubende und
mühsame, aber ungemein verdienstvolle Arbeit übernähme. Lange Literatur-
suchen nach den Erstbeschreibungen würden in Zukunft erspart bleiben,
zahllose Synonymiefragen könnten ein für allemal geklärt werden und damit
den Malakologen Europas ein einmalig wertvolles Instrument in die Hand
gegeben werden. Ich hoffe allerdings, dassSie nicht annehmen, dass ich mich
auch dieser Aufgabe unterziehen werde, denn das ginge wirklich über meine
Kräfte.

Das Aufgabengebiet der UNITAS MALACOLOGICA EUROPAEA ist natürlich
primär auf das europäische Gebiet beschränkt. Ich halte es aber für ausser-
ordentlich wichtig, auch die Zusammenarbeit mit aussereuropäischen Ver-
einigungen zu fördern, ich erwähne nur die AMERICAN MALACOLOGICAL
UNION, die AUSTRALIAN MALACOLOGICAL SOCIETY und andere. Hier
in Europa stellt ja die UNITAS die Dachorganisation aller europäischen
malakologischen Gesellschaften dar und bewahrt auf diese Weise den Zusam-
menhang. Wesentlich ist jedoch auch meiner Ansicht nach die Zusammen-
arbeit der kontinentalen Organisationen, in denen ja die kleineren Verbände
zusammengeschlossen sind. Ich stelle mir die Zusammenarbeit in erster
Linie so vor, dass durch Austausch der jeweiligen Publikationen oder Pro-
ceedings der wissenschaftliche Kontakt gegebenistunddamiteine Zusammen-
arbeit der Mitglieder derartiger Vereinigungen ermöglicht und erleichtert
wird.

Es wäre Aufgabe der jeweiligen Präsidenten dieser Vereinigungen, mitein-
ander Kontakt aufzunehmen und vielleicht sogar darüber hinaus eine gewisse
Koordination der Themen von Symposien zu erreichen. Da nicht alle euro-
päischen Malakologen Zugang zu aussereuropäischen Publikationen haben,
sollte die UNITAS hier vermittelnd eingreifen und diese Verbindung zu-
standebringen.

Ich bitte, mich gerade in diesem Punkt nicht misszuverstehen. Ich bin
ein glühender Verfechter der Separierung der europäischen Malakologen in
einer eigenen Vereinigung, mit eigenen Kongressen. Ichbin strikt gegen eine
internationale Vereinigung der Malakologen, die es in Hinkunft einem Gross-
teil der europäischen Malakologen unmöglich machen würde, die regelmässigen
Kongresse zu besuchen. Und damit allein wäre schon eine der wesentlichsten
Funktionen der UNITAS zunichte gemacht. Solange die Kongresse ausschliess-
lich inEuropa abgehalten werden, istesfür die meisten von uns doch irgendwie
im Bereich der Möglichkeiten, daran teilzunehmen. Was ich aber anregen
möchte, ist eine lockere Verbindung der einzelnen grossen malakologischen
Vereinigungen der Welt.

Bewahren wir uns unsere Unabhängigkeit, stellen wir dasgrosse Aufgaben-
gebiet Europa in den Mittelpunkt unserer Betrachtungen, streben wir aber
jene Verbindungen mit aussereuropäischen Vereinigungen an, die unsere
Arbeiten erst sinnvoll machen durch das gemeinsame Zielder malakologischen
Forschung. Und wenn sich die UNITAS MALACOLOGICA EUROPAEA dieser
Vermittler- und Verbindungsrolle besinnt, wenn sie diese einmalige Chance
ergreift, die sie im weltweiten Rahmen einnehmen kónnte, dann wiirde sie in
Zukunft jene Bedeutung gewinnen, die ich ihr als scheidender Prásident von
ganzem Herzen wiinsche!

OLIVER E. PAGET

PROC. THIRD EUROP. MALAC. CONGR.
RESUME

Presidential Address by Dr. PAGET

By the following suggestions the activity of UNITAS, up to now mostly

limited to the organisation of Congresses, shall be activated.

2)
3)

5)
6)

Invitation to all members to prove their interest in the UNITAS by active
cooperation with suggestions for the committees and places for coming
congresses.

Comprehension of all malacologists together with their field of work. x)
Appreciation of the importance of museum-collections and their curators
by including in coming congresses an extra day for discussion of their
problems.

Comprehension of the newest malacological literature of a current year
by sending the published papers to Dr. Paget. Annually a list will be sent
to all participants. x

Continuing comprehension of private-museum and institute-collections to
complete the started list. x)

Fauna lists of all European countries, according to the newest system
with the final aim of a Fauna Europaea.

Cooperation of the large continental malacological organisations by ex-
change of the “Proceedings,” and making them available to all members
at the different congresses.

Creation of a permanent UNITAS-Committee, the members of which are
willing to work on these tasks without termination and independently of
the congresses.

For all projects, mentioned under 2), 4) and 5), Dr. Paget is willing to
work on them when authorized by the UNITAS.

Voici quelques propositions par lesquelles l’activité de l’UNITAS, qui,

jusqu’à maintenant s’est bornée a l’organisation des congrès réguliers,
devrait être intensiviée:

Les participants devraient faire preuve de leur intérêt vis-a-vis de cette
organisation en faisant des propositions concernant les lieux de congrès
et les comités.

Le recensement de tous les malacologues en indiquant l’orientation de
leurs recherches. x)

La mise en valeur de l’importance des collections de musées et de leurs
directeurs de section responsables en consacrant une journée entière à
leurs problèmes au cours des congrès.

Le recensement des travaux récents dans le domaine de la malacologie
pour un an en Europe en envoyant à M. Paget les travaux en question.
Tous les ans, une liste sera envoyée à tous les participants. x)

Le recensement intensifié des collections privées et des collections
appartenant a des instituts différents et la continuation de la liste actuelle.
x)

La création d’un ensemble de listes sur la faune des pays européens
d’après le système de plus moderne en vue d’une faune européene.
La collaboration des grandes organisations des malacologues par l’échange

PAGET: PRESIDENTIAL ADDRESS

des publications respectives. Aux différents congrès les participants

devraient avoir accés a ces travaux.
8) La création d’un comité permanent de UNITAS, dont les membres se

chargeront de l’exécution de ces travaux sans limite temporelle.

x) M. Paget se déclare prét d’effectuer les travaux cités sous 2), 4) et 5) si
VUNITAS les lui confère.

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PROC. THIRD EUROP. MALAC. CONGR.

REPORT ON THE GENERAL ASSEMBLY OF
UNITAS MALACOLOGICA EUROPAEA

by the Secretary, Dr. A. ZILCH

The 1968 meeting of the General Assembly of UNITAS MALACOLOGICA
EUROPAEA took place at the Vienna Natural History Museum on Friday,
September 6, at 6:00 p.m. Sixty-five memberswere present. We again thank
Mr. G. I. Crawford for being the Chairman.

The assembly followed the order of the agenda which had been mailed to
all members on 31 May 1968 (dated 4 June), in accordance with paragraph 8
of the Rules of UNITAS.

1. Confirmation of new members
The new members of UNITAS as shown in an appendix to the agenda were
confirmed.

2. Report by the President on UNITAS’ work

Dr. Paget, the President, gave ashort reviewon the work of UNITAS during
the last 3 years, especially the different letter actions of the Secretary. Itis
to be noted that the amended version of the Rules containing the alterations
as approved by the last General Assembly in Copenhagen in 1965 was pub-
lished and mailed to all members in June 1966. On 3 May 1967, a meeting
of the Council took place in Basle.

Twenty-five new members had joined UNITAS since the last General As-
sembly in August 1965. Three members died (Dr. Г. В. Cox in 1965, Dr. H. Е.
Quick in 1967, and Dr. W. J. Rees in 1967); 2 members resigned. Thus, the
number of members increased from 120 in August 1965 to 140 in September
1968. The 140 members consisted of:

Ordinary members (personal 108, collective 9).............. 117
Corresponding, members (all personal). 000... 23
The 140 members came from 31 countries.
a) Ordinary members in 20 countries:
Algeria (1), Austria (2), Belgium (1), Denmark (7), Egypt (1),
France (16), Germany (13), Great Britain (21), Hungary (2), Israel (2),
Italy (13), Netherlands (18), Norway (2), Poland (1), Portugal (1),
Rumania (2), Sweden (4), Switzerland (7), Turkey (1), Yugoslavia (2).
b) Corresponding members in 11 countries:
Australia (1), Brazil (1), Canada (1), Ethiopia (1), Ghana (1), Hawaii
(1), Japan (1), New Zealand (1), Nigeria (2), South Africa (1), U.S.A.
(12).

3. Presentation of statement of accounts by the Treasurer

Dr. Forcart, the Treasurer, presented the following statement of accounts
(in Swiss Francs) for the period from July 1, 1965, to August 8, 1968. The
statement had been approved by the auditors Mr. Dance and Mr. Kuiper.

De Fr,
ICONE ails (es ee u 4, 400.40
Bepengiture. . 3 4. 2 es о. Е
Excessiof INCOME . о. с ооо сс, « 3,089.09

(17)

PROC. THIRD EUROP. MALAC. CONGR.

Assets Schweizerischer Bankverein Basel

(Е.Н. 941085) Pas Fe A ER AA SE Ae A
Balance: 1.1.1965 ee. хо доме ош EAS
Balance 8.8.1968: о er QU COOPER
EIXCOSSing Hu nen e fl ot 7 лена di En Пре ВАА

4. Approval of acts of councillors

The acts of the councillors for the periodfrom 1965 to 1968 were approved.

In February 1968 all ordinary personal members of UNITAS were invited
to nominate members for the new Council for the period from 1968 to 1971,
in accordance with paragraph 11 of the Rules. To his regret the Secretary
has received only one proposal which was signed by 6 ordinary members on
May 25, 1968, and, therefore, corresponded with the Rules. The Council of
UNITAS agreed to this proposal. According to paragraph 11 of the Rules, the
proposal was mailed as a ballot to all 105 ordinary personal members on
July 10, 1968. At the General Assembly the Secretary announced the follow-
ing result of the voting in which 60 members had participated:

yes no abstention

President:

Dr. E. Binder, Switzerland 59 - 1
Vice President:

Dr. F. E. Loosjes, Netherlands 57 - 3
Secretary:

Dr. A. Zilch, Germany 60 - -
Treasurer:

Dr. L. Forcart, Switzerland 60 - -
Member of Council:

Mr. G. I. Crawford, England 59 - 1

Thus the above office holders were elected members of Council.

6. Election of auditors for the period 1968-1971
The following members were appointed auditors: Mr.S. P. Dance, England,
and Avv. Dott. F. Toffoletto, Italy.

7. Subscription for the period 1968-1971
The annual subscription rates of 10.00 Swiss Francsfor ordinary members
and 5.00 Swiss Francs for corresponding members were not altered.

8. Fixing of year and place of the next Congress
The President-Elect, Dr. Binder, invited the members of UNITAS to the
next Congress in Geneva in 1971. The invitation was accepted.

9. Any other business

Lengthy discussions arose about the suggestions of Dr. Paget as indicated
in his Presidential Address (see above). Finally the General Assembly author -
ized Dr. Paget to carry out the proposals numbers 2, 4 and 5; the remaining
subjects were postponed to the next General Assembly which will take place in
Geneva in 1971. By this assignment of Dr. Paget, the members of UNITAS
are at the same time requested to give him any assistance possible in
accomplishing his task.

A. ZILCH

PROC. THIRD EUROP. MALAC. CONGR.

RAPPORT SUR L’ASSEMBLEE GENERALE DE L’UNITAS
MALACOLOGICA EUROPAEA

L’assemblée générale de l’UNITAS MALACOLOGICA EUROPAEA s’est
tenue le vendredi, 6 septembre 1968, a 18 h au Musée d’Histoire Naturelle
de Vienne. 65 membres y étaient présents. Nous remercions Monsieur G. I.
Crawford d'avoir une fois de plus accepté de présider les débats.

L'assemblée s'est tenue a l’ordre du jour qui fut envoyé le 31 mai 1968
(daté du 4 juin). conformément au $ 8 des statuts à tous les membres.

1. Confirmation des nouveaux membres
Les nouveaux membres de l’UNITAS ont été confirmés.

2. Rapport du président sur sa gestion

Le président, Docteur Paget, a donné un bref résumé sur l’activite de
l’UNITAS au cours des trois dernières années. Le texte des nouveaux statuts,
ou les modifications décidées lors de l’assemblée générale de 1965 a Kopen-
hagen ont été apportées, a été envoyé en juin 1966 a tous les membres. Le
3 mai 1967 a eu leiu une séance du comité a Bale.

25 nouveaux membres sont entrés dansl’UNITAS depuis la dernière assem-
blée générale en aoút 1965. 3 membres sont décédés (Dr. L. В. Cox 1965,
Dr. H. E. Quick 1967 et Dr. W. J. Rees 1967), 2 membres ont démissioné,
се qui fait que le nombre est jusqu'en septembre 1968, monté a 140 (voir
tableau synoptique dans le texte anglais).

Le trésorier, Dr. Forcart, a donné un aperçude l’état financier du l’UNITAS
pour le temps du 1 er juillet 1965 jusqu’au 8 aoút 1968. La comptabilité a
été contrólée par les Messieurs Dance et Kuiper (voir tableau synoptique
dans le texte anglais).

4. Décharge du comité
L’assemblée a donné au comité 1965-1968 décharge pour sa gestion.

5. Election du nouveau comité pour 1968-1971

En février 1968 tous les membres individuels ordinaires de L’UNITAS ont
été invités А envoyer des propositions pour 1'élection du nouveau comité pour
1968-1971, conformément au § 11 des statuts. Malheureusement le secré-
taire n’a recu qu’une proposition conforme aus statuts et signée de six
membres ordinaires. Le comité de l’UNITAS a adopté cette proposition.
Selon le § 11 des statuts cette proposition a été envoyée le lo juillet 1968 a
tous les 105 membres ordinaires individuels pour vote. А l’occasion de
l’assemblée générale le secrétaire a publié le résultat de l’élection, à laquelle
60 membres ont participé (voir tableau synoptique dans le texte anglais). Les
membres proposés ä 1'élection ont été ainsi élus dans le nouveau comité.

6. Election des réviseurs des comptes pour 1968-1971
Mr. S. P. Dance, Angleterre et Avv. Dott. F. Toffoletto, Italie, ont été
élus réviseurs des comptes.

7. Fixation de la cotisation pour 1968-1971
La cotisation annuelle de SF 10.00 pour membres ordinaires, et SF 5.00
pour membres correspondants n'a subit aucun changement.

PROC. THIRD EUROP. MALAC. CONGR.

8. Choix de l’année et du lieu du prochain congrès
Le président élu, Dr. Binder, a invité les membres de 1'UNITAS pour le
prochain congrés en 1971 a Genéve. Cette invitation fut acceptée.

9: Divers

Les propositions du Dr. Paget dans sa “Presidential Address” (priére de
s’y référer) ont donné lieu a des discussionsanimées. L’assemblée générale
a chargé finalement Dr. Paget de réaliser les propositions 2, 4 et 5, les autres
points ont été ajournés jusqu’a la prochaine assemblée générale a Сепёуе
en 1971. Cette mission donnée au Dr. Paget constitue en même temps une
invitation aux membres mêmes de l’UNITAS de l’aider dans sa tâche dans
toute la mesure du possible.

BERICHT UBER DIE GENERALVERSAMM LUNG DER
UNITAS MALACOLOGICA EUROPAEA

Die Generalversammlung der UNITAS MALACOLOGICA EUROPAEA fand
am Freitag, dem 6. September 1968, um 18 Uhr im Naturhistorischen Museum
in Wien statt. Es waren 65 Mitglieder anwesend. Wir danken Herrn G. I.
Crawford, dass er wieder das Amt des Chairman tibernommen hat.

Die Versammlung folgte der Tagesordnung, die am 31. Mai 1968 (Datum
vom 4. Juni) gemäss $ 8 der Satzung an alle Mitglieder verschickt worden ist.

1. Bestátigung neuer Mitglieder
Die neuen Mitglieder der UNITAS wurden bestátigt.

2. Tätigkeitsbericht des Präsidenten

Der Präsident, Dr. Paget, gab eine kurze Übersicht über die Tätigkeit der
UNITAS während der letzten drei Jahre. Die Neufassung der Satzung, unter
Berücksichtigung der auf der Generalversammlung in Kopenhagen 1965 be-
schlossenen Abänderungen, ist im Juni 1966 an alle Mitglieder verschickt
worden. Am 3. Mai 1967 hat eine Vorstandssitzung in Basel stattgefunden.

Seit der letzten Generalversammlung im August 1965 sind 25 neue Mit-
glieder der UNITAS beigetreten. Drei Mitglieder sind verstorben (Dr. L. R.
Cox 1965, Dr. H. E. Quick 1967, Dr. W. J. Rees 1967), zwei Mitglieder haben
ihren Austritt erklärt. Dadurch ist die Mitgliederzahl bis September 1968
auf 140 angestiegen. (Vgl. die Zusammenstellung inder englischen Fassung).

3. Vorlage des Rechnungsabschlusses durch den Schatzmeister

Der Schatzmeister, Dr. Forcart, gab eine Übersicht über die finanziellen
Verhältnisse der UNITAS für die Zeit vom 1. Juli 1965 bis 8. August 1968.
Die Rechnungsführung ist von den Herren Dance und Kuiper geprüft worden.
(Vgl. die Zusammenstellung in der englischen Fassung.)

4. Entlastung des Vorstandes
Der Vorstand (1965-1968) wurde entlastet.

5. Wahl des neuen Vorstandes für 1968-1971
Im Februar 1968 wurden alle persönlichen ordentlichen Mitglieder der
UNITAS aufgefordert, Vorschläge für die Wahl des neuen Vorstandes für

PROC. THIRD EUROP. MALAC. CONGR.

1968-1971, entsprechend $ 11 der Satzung, einzureichen. Der Sekretár hat
leider nur einen Vorschlag erhalten, der der Satzung entsprach und von sechs
ordentlichen Mitgliedern unterzeichnet war. Der Vorstand der UNITAS hat
sich diesem Vorschlag angeschlossen. Gemáss $ 11 der Satzung ist dieser
Vorschlag am 10. Juli 1968 an alle 105 persónlichen ordentlichen Mitglieder
zur Wahl abgeschickt worden. Auf der Generalversammlung gab der Sekretár
den Ausgang der Wahl bekannt, an der sich 60 Mitglieder beteiligt haben (vgl.
die Zusammenstellung in der englischen Fassung). Die zur Wahl vor-
geschlagenen Mitglieder wurden damit in den neuen Vorstand gewáhlt.

6. Wahl der Rechnungsprüfer für 1968-1971
Zu ‚u Rechnungsprüfern wurden ernannt: Mr. S. P. Dance, England, und Avv.
Dott. F. Toffoletto, Italien.

7. Festsetzung des Beitrages flr 1968-1971

Der Jahresbeitrag von 10. 00$. Fr. für ordentliche Mitglieder und 5.00 $. Fr.
ftir korrespondierende Mitglieder wurde nicht geándert.

8. Bestimmung des Jahres und Ortes des náchsten Kongresses

Der gewählte Präsident, Dr. Binder, hat die Mitglieder der UNITAS für
den nächsten Kongress 1971 nach Genf eingeladen. Diese Einladung wurde
angenommen.

9. ‚Verschiedenes

Über die von Dr. Paget in seiner “Presidential Address” (siehe dort)
gemachten Vorschläge gab es längere Debatten. Die Generalversammlung
beauftragte schliesslich Dr. Paget, die Vorschläge 2, 4 und 5 durchzuführen;
die übrigen Punkte wurden bis zur nächsten Generalversammlung 1971 in
Genf vertagt. Dieser Auftrag an Dr. Paget stellt aber gleichzeitig auch einen
Auftrag an die Mitglieder der UNITAS selbst dar, ihn bei der Durchführung

seines Vorhabens weitestgehend zu unterstützen.

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PROCEEDINGS

of the

Symposium on MOLLUSCS AS PARASITES OR THEIR TRANSMITTERS

(Vienna, 2-3 September 1968)

MALACOLOGIA, 1969, 9(1): 25-34

PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

CONTRIBUTION TO THE MORPHOLOGICAL AND BIOCHEMICAL
IDENTIFICATION OF SOME STRAINS OF
THE BULINUS TRUNCATUS GROUP

J. Fraga de Azevedo, Mariade Lourdes Xavier, Maria Margarida Pequito
and Manuela Simöes

Laboratorio de Estudos de Radioisotopos, Junta de Investigaçôes
do Ultramar, Lisboa

INTRODUCTION

When a plan is organized to fight against Schistosoma in a certain geographical area,
the first objective is to evaluate the local presence, distribution and prevalence of the
vector snails. For that purpose it isfundamental to do a careful survey in the locality
concerned in order to determine important aspects of the problem, beginning with a
detailed investigation of the existing water bodies in order to collect the snails for
study of their morphology, taxonomy and systematics. Simultaneously, their ecology,
biology and action as parasite vectors must be considered.

The majority of vector snails usually present many difficulties in classification,
either by external or internal anatomy. On the other hand, it is well known that the
same species of snail can present remarkable differences in its susceptibility for the
same species of Schistosoma, as happens, for instance, with Biomphalaria glabrata
of Recife, Brasil. The latter can be experimentally infected with local S. mansoni at
the rate of 83.9%, while the same snail species from Bahia, Brasil can be infected
with the same strain of Schistosoma only at the rate of 1.7% (BARBOSA & BARRETO,
1960). Also, some years ago (AZEVEDO, et al., 1954) it was possible for us to infect
Planorbarius metidjensis from Algarve, Portugal withS. haematobium from Portuguese
Guinea, but later, with the same geographical strains of both snail and parasite it was
not possible to obtain an infection, even after several experiments. Additionally,
some years ago we could infect P. metidjensis with the Portuguese strain of S.
haematobium (AZEVEDO, et al., 1948) at the rate of 80.9%.

The above mentioned alterations may be the result of genetic changes occurring
in the snail populations, which result inthe appearance of strains with different charac-
teristics and behaviour as intermediate hosts of trematode parasites. Paralleling the
occurrence of genetic changes inthe snail populations may be variations in the chemical
constitution of the snails, as was shown by WRIGHT (1964) by the chromatographic
characteristics of the mucus which showed differences between individuals of the same
population, which can vary with the snail’s ages.

As a contribution to the knowledge of this problem, we have studied and compared
the morphology and some aspects of the biochemical constitution of certain geographi-
cal strains of the Bulinus truncatus group with susceptibility to Schistosoma haema-
tobium from Portuguese Guinea and from Angola. These results will be presented
in the following sections. But first, we wish to discuss briefly the B. truncatus snail
group and the S. haematobium parasite complex.

The Bulinus truncatus group

Until now 12 strains have beendescribedinthe Bulinus truncatus group (MANDAHL-
BARTH, 1965). Concerning the representation in Portugal of that group, Mandahl-Barth
thinks that the different morphology of the mesocones of lateral teeth of the radula is

(25)

26 PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

enough to consider it as a species particular to Portugal, giving it the designation
of Bulinus (B.) contortus.

Meanwhile prior observations made by Medeiros (1962), and later one by CRISTO
(1968) about the Portuguese Bulinus of Coimbra (center of the country) in comparison
with the B. truncatus from Teheran and Bagdad, confirmed the observations of
MANDAHL-BARTH about the morphology and size of the mesocones of the lateral
teeth, but the authors thought that such small differences did not justify the specific
differentiation proposed by MANDAHL-BARTH.

In order to clarify the classification on the Portuguese Bulinus we have made some
biomorphological studies on 2 populations: the northern one (Coimbra) belonged to the
strain studied by MANDAHL-BARTH, whereas the strain from southern Portugal (Al-
garve) (Fig. 1) has now been studied forthe first time. As the ecological conditions of
Algarve are very different from those of the north, we thought that it would be con-
venient to consider representatives of the two areas. Indeed the southern territory
of Portugal is much warmer than the northern, and presents other particularities due
to the chain of high mountains that limits its north boundary.

At the same time we studied representatives of Bulinus truncatus from Tchad,
Liban and Egypt, the only ones at our disposal.

The Schistosoma haematobium complex

The morphological characteristics fundamental to this complex concern the shape
and size of the eggsandadults. The common biological characteristics are: mammals
as definitive hosts; Bulininae snails as vectors; and special localizations in the reser-
voirs. Concerning the vectors, it is necessary to mention one exception: S. haemato-
bium of southern Portugal, which has a Planorbinae, Planorbarius metidjensis, as
intermediate host.

In view of the special ecological, 9 : =
morphological and biological character-
istics of the formerly Portuguese S.
haematobium (*) we propose that it be
designated S. haematobium europeense,
having in consideration particularly its
intermediate host.

COMPARATIVE STUDY OF THE
DIFFERENT COMPONENTS OF THE
BULINUS TRUNCATUS GROUP

We wished to study the greatest pos-
sible number of representatives of the
Bulinus truncatus group, but unfortunate -
ly we have been able till now to obtain
only the Portuguese strains from north
and south and the mentioned representa- se
tive of Bulinus truncatus. We present
now the results obtained from the com-
parative studies of these strains, con- gitves

9 8 7
*A survey made in Algarve in Мау 1966 did
not reveal any case of vesical bilharziasis FIG. 1. Localities in Portugal from which
(Azevedo, et al. , 1966). snail specimens ofthe current study originated.

AZEVEDO, XAVIER, PEQUITO and SIMOES 27

sidering their morphology, chromatography of the mucus, electrophoresis of the
blood and the susceptibility “in vivo” and “in vitro” to infection by two geographically
different strains of S. haematobium, one from Portuguese Guinea and the other from
Angola.

Morphology

We must consider here as main characteristics the shell, the radula and the genitalia.

Shell. There are not great differences between the shells of the strains concerned,
with the exception of the Tchad specimens which had shorter spires and more obtuse
apexes. Also the shell from the Portuguese Bulinus is darker and it seems that the
shell of the northern strain is smaller than the shell of those from Algarve. This
difference may occur because the northern region is colder, thus not allowing as good
a development as in the south. From measurements of 6 specimens (Table 1), it
seems that the northern specimens are smaller than the southern ones. The ratio of
total height of the shell to height of the aperture (Table 2) is bigger in the Bulinus from
southern Portugal than in the specimens from the north, and bigger than those from
Egypt, Liban and Tchad.

TABLE 1. Different sizes of the snails studied, in mm.

TABLE 2. Relation between the total height of the shell and the height of the aperture

North | 16
Portugal = =
South 178
Tchad 1. 38
JE
Egypt 1.54
Liban 1. 42

Genitalia. As remarkable differences in the species studied, we observed that all
the strains from Portugal and Tchad were aphallic, but those from Liban and Egypt
presented a well developed penial complex. This complex was similar in the 2 strains
except that the preputium of the Liban specimens was narrower and longer than that
of the Egyptian specimens, and each of them had a vergic sheath longer and narrower
than the preputium. The prostate was always round and smaller in the aphallic speci-

28 PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

mens, with a bladder-shaped defferent canal which, in the Portuguese speci-
mens, is narrower and longer than in those of Tchad.

Radula. There are some differences in the morphology of the mesocones of the
lateral teeth; in Bulinus from Coimbra and Libanthey are pointed, while the more typi-
cal arrow-head shape is seen in the specimens from Tchad and Algarve, and though
not so distinct, in those from Egypt. In fact, in each geographical strain studied the
central, lateral, intermediate and marginal teeth had their own different and peculiar
morphology.

Chromatography of the mucus

MICHEJDA (1958) and MICHEJDA and cols. (1958) observed that the fluorescence
pattern obtained with the surface mucus of the snail was characteristic of the species.
The method was further applied to Lymnaea (WRIGHT, 1964), who concluded that by
using chromatography it is possible to determine the genetic characteristics of the
populations.

In order to clarify the systematics of the mentioned Bulinus truncatus group, we
studied the chromatography of the mucus of the strains at our disposal. Although more
observations are needed, the first interesting results obtained justify their presen-
tation here.

Methods. We used at first the circular technique of Wright (1964), but the chromato-
grams so obtained were not satisfactory, perhaps because we could obtain a very small
quantity of mucus. Meanwhile we tried ascending and descending paper chromatogra-
phy, employing as the solvent butanol, acetic acid and water in the proportions of
4:1:5. We obtained the best results with the ascending technique. After chroma-
tography, the sheets were exposed to ammonia vapour, and then viewed under u.v.
light (3504, Camag universal u.v. lamp).

Results. The results presented in Table 3 were not the same for each Strains.
Thus, for the snails from Tchad we observed 4 spots and only 3 for the others. In
all of them appeared 1 white spot with a low Rf value, followed by another smaller
spot with a nearly circular perimeter of bright blue, which was more intensive in
the snails from Egypt and Liban than in those from Portugal.

The substance with the highest Rf value appears in snails from Tchad, as a bright
yellowish spot; it is light yellow in the Bulinus from Portugal and lilac blue in the
snails from Egypt and Liban. A fourth fluorescent spot was seen in the snails from
Tchad - a yellowish spot lighter than the former.

TABLE 3. Rf values and chromatographic spots in the different strains of Bulinus

ee i ae 7 2
RES (*) 0. 20 0. 25 - 0. 40 0.40 - 0.60 | 0.60 - 0.80
— == ES — = == = += Е == ЕЕ + ae

Portugal Whitish Blue Pale yellowish -

i 7
Tchad ? Strong blue Strong yellowish Yellow

H +
Egypt 4 Strong blue Lilac blue | =
Liban 2 | Strong blue "Lilac blue -

(*) RE = distance travelled by substance

distance travelled by solvent front

AZEVEDO, XAVIER, PEQUITO and SIMOES 29
Electrophoresis of the blood

Studies conducted by TARGETT (1963) on Bulinus (B.) truncatus showed that fraction-
ation of blood proteins occurred. Snail sizes were 4.5 x 2.5 mm and 9.0 x 5.0 mm
(height and diameter). The best results were obtained with alkaline buffer of high pH.
In applying this method, we used snails of several ages and we tried several buffers
and different voltages, but we had difficulties obtaining good fractionations; this was
mainly dependent of the buffer pH, which must reach 11.8.

Our results show that 3 fractions are present in Bulinus from Portugal and Egypt
and 2 fractions in the snails from Tchad and Liban, in addition to the biggest spot
which corresponds to hemoglobin (Table 4).

Meanwhile the size of the snails, related to their age, surely has an influence on
the results, and this we intend to study; it is possible with our technique to take blood
several times from the heart of a snail without killing it.

TABLE 4. Showing comparative separations of blood proteins from Bulinus of Portugal, Tchad,
Egypt and Liban

Strains Sizes (mm) Separations obtained | Migration from application point
H-6 Hemoglobin + Hemoglobin 2° CM
North ae, 1’ cm
D- 4.5 three fractions The others —— 1.5 cm
I. 7 cm
Portugal —— - —— (er ——
Н-5.2 Hemoglobin + Hemoglobin 2 cm
South en 1 em
D - 3.6 three fractions The others —— 1.5 cm
i em
H - 5.2 Hemoglobin + Hemoglobin 9 em
Tchad Lee
В 3.2 two fractions The others —— 1. 4 cm
1.. 6. Cm
Н-5.6 Hemoglobin + Hemoglobin 2 CM
Egypt a т em
D-4 three fractions The others —— 1.6 cm
1.8 em
H- 5.2 Hemoglobin + Hemoglobin 2,1 Cm
Liban № item
D - 3.6 two fractions The others — 1.6 cm

Susceptibility of the snails to Schistosoma haematobium

In order to evaluate susceptibility we can study the subject in the field, determining
the natural rate of infection of the snails by cercariae, but it is always desirable that
these observations be confirmed by experimental study in the laboratory. For this

30 PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

purpose we can use the classical method of infection of the snails “in vivo” or we can
try “in vitro” infection. We have applied these 2 methods to evaluate the suscep-
tibility of the snails concerned to the geographical strains of S. haematobium studied,
one from Portuguese Guinea and the other from Angola.

Study “in vivo” of the susceptibility of the snails to S. haematobium from Portuguese
Guinea and from Angola.

Each snail was exposed to 3 miracidia of human origin and the susceptibility to
infection, and its degree was evaluated by the rate of infection of the snails, number
of cercariae eliminated, precocious mortality, longevity and degeneration or normal
development of the miracidia as seen in sections of the snail organs. To accomplish
this study we evaluated also the virulence of the cercariae eliminated, as proof
of the efficiency of the vector; this was done by determining the relation between the
number of cercariae utilized to infect the experimental animal, and the number of
worms obtained, as well as the relative proportion of animals that eliminated viable
eggs.

As definitive host we used the hamster Cricetus auratus. Each animal was exposed
to 500-600 cercariae and sacrificed at the endof 4 weeks. The eggs were obtained from
the liver and bowel, and the miracidia used to infect new snails. We collected the
adult worms by section and pression of the liver.

The results obtained are presented in Table 5. Concerning the strains from Portu-
guese Guinea, we have verified that there is greater affinity between the 2 Portuguese
populations and the strain from Tchad, than between the Portuguese populations and
those from Liban and Egypt; the rates of infection were respectively 27.6, 21.4 and
49.2%. The Bulinus from Liban was refractory and the Bulinus from Egypt was in-
fected only at the rate of 4.5%.

The number of eliminated cercariae was much higher in the snails of the Tchad
population than in the Portuguese ones; i.e., the former 25 snails eliminated 10,880
cercariae, while the 240 snails from Algarve eliminated 8,043, and 501 specimens from
Coimbra eliminated only 6,575.

The proportion of infected animals that produced viable eggs was highest in the
Portuguese population from Coimbra; this was followed by the strain from Tchad and
finally that from Algarve. On the basis of these results it is not clear if the snails
from Tchad are more susceptible than the Portuguese ones, because a greater number
of the former snails were submitted to theinfection; this might explain the differences
observed. Nevertheless, we can conclude that there are some differences between
them and those from Egypt and Liban, a conclusion which is not in accordance with
the results obtained by the chromatographic method.

Concerning the strain of S. haematobium from Angola, we have tried only a small
number of snails (this strain is very recent in our laboratory) and we cannot consider
the negative results and the snail control as conclusive. With the snail control,
Bulinus (Ph.) africanus, only three became infected; but up to now, 48 days after the
infection, they have eliminated a great number of cercariae, which we have utilized
to infect hamsters. Meanwhile, the fact that the control snails were infected proves
that the experimental conditions were good. The low rate of infection observed is also
perhaps the consequence of the great mortality whichoccurred between the 3rd and the
12th days after infection; only 3 surviving tillthe 30th day, when they were then placed
in a stove at 37° C in order to verify the elimination of cercariae.

Study of the susceptibility of the snails “in vitro”.

As an alternative to the classic method of evaluating the susceptibility of the snails,
BENEX (1965) had the idea of evaluating susceptibility by submitting only the tentacles,

AZEVEDO, XAVIER, PEQUITO and SIMOES

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32 PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

taken off the snails and maintained “in vitro” ina special nutritive medium, to the
miracidea. We also have used this method, with the same very rich nutritive culture
medium, having verified that the tentacles could survive for 26 days, retaining a nor-
mal appearance and good vitality, although this reduced gradually with time, as was
evident from a reduction of their movements. With time they became round, and lost
the ability to move at the end of 5-6 days, with the exception of the cilia. At the same
time there were signs of degeneration of the nucleus and nervous cells, and loss of
mucus cells.

Until now it has only been possible to attempt infection of Bulinus from Coimbra,
Tchad, Liban and Egypt with a strain of S. haematobium from Angola. Sixty miracidia
were used with each tentacle on the first day of its maintenance in the medium, and
sections were made at different intervals (24 - 72 hours) in order to follow the infec-
tion; however, we have obtained no infection. As а control, however, we submitted the
tentacles of Biomphalaria glabrata to infection with miracidia of S. mansoni from
Brasil. We obtained a rate of infection of 10% as proof of the good experimental
conditions; this is confirmed by the normal aspect of the evolution of the miracidia
in the tentacle.

From the results obtained from the “in vivo” and “in vitro” studies of susceptibility
of the snails concerned to the Schistosoma haematobium of Angola, it seems that they
are unsusceptible to it. Meanwhile other researches are in progress in order to arrive
at definitive conclusions, and particularly to seeifthese results are the first proof that
S. haematobium from Portuguese Guinea and Angola are biologically different.

INTERPRETATIONS AND CONCLUSIONS

In this study several morphological, biological and chemical factors were considered
in order to establish the relationship that exists between some B. truncatus strains
and two geographical strains of African.S. haematobium. It is, nevertheless, difficult
to define these relationships, and more and detailed studies are necessary to arrive
at definitive conclusions.

On the basis of the results obtained, we can arrive at the following conclusions:

a) morphology; there are some differences between the shell, the radula and genital
organs of the strains examined.

b) chromatograms of the mucus show a close similarity between the Bulinus from
Egypt and Liban and a very distinct difference between the latter and the Bulinus
from Tchad and Portugal (between these 2 there is little similarity). All show
the first spots with the same colour, although with differences of intensity, but
the Tchad Bulinus shows a fourth spot.

c) electrophoresis shows also some differences in the strains studied, particularly
between those of Tchad and Liban on the one hand and those of Portugal and
Egypt on the other.

d) there were some differences in the degree of susceptibility “in vivo” and “in
vitro” of the snails studied to the S. haematobium from Portuguese Guinea and
none was susceptible to S. haematobium from Angola; this seems to prove that
the S. haematobium from Portuguese Guinea is biologically different from the
same species of Schistosoma from Angola.

e) the differences observed in the susceptibility “in vivo” between the strains from
Liban and Egypt are in accordance with the differences also observed in the
respective chromatograms.

f) the electrophoregrams of snail blood also show some differences between them
which are in accordance with the differences in the respective chromatograms.

AZEVEDO, XAVIER, PEQUITO and SIMOES 33

PROSPECTS TO BE CONSIDERED

With our paper we hope to have given an idea of the difficulties encountered while
investigating the relationship between Schistosoma and its snail vectors, and which
justify new and more intensive studies. We think that the main reasons for our in-
complete information are a consequence of the limited knowledge that we have about
the biology, physiology and genetics of the snails and of the schistosomes themselves.
It is therefore desirable to increase research in these fields, and we think that an
important contribution can be made by the electronic microscope and by developing
methods for the chemical and genetic studies. The subjects mentioned are only ex-
amples of what we need todo; muchother research is necessary in order to clarify the
important problem of differences existing between the geographical strains of Schisto-
soma haematobium and the corresponding Bulinus truncatus vectors, and the methods to
use for their specific classification.

SUMMARY

In order to study the differences between the components of Bulinus truncatus group,
as vectors of the strains of Schistosoma haematobium complex, studies were made of
1) the morphology of some geographic strains; 2) the chromatography of their mucus;
and 3) the electrophoresis of the blood. These were compared with the susceptibility
of those snails to 2 geographical strains of S. haematobium, one from Portuguese
Guinea and the other from Angola.

From the results obtained, it seems that the snails present remarkable differences
between them, particularly concerning their biological behaviour; it seems also that
the strain of S. haematobium from Portuguese Guineais different from the Angola one.

BIBLIOGRAPHY

AZEVEDO, J. Е. de, FARO, М. М. & GOMES, Е.А. C., 1954, Susceptibility of
Planorbis metidjensis to Schistosoma haematobium of Portuguese Guinea and
to S. mansoni of Mozambique. Anais Inst. Med. Trop., Lisbon, 11: 251-260.

AZEVEDO, J. Е. de, SILVA, J. B., COITO, A. M., COELHO, М. Е. € COLACO, A. T. F.,
1948, O foco portugués de Schistosomiase. Anais Inst. Med. Trop., 5: 175-223.

AZEVEDO, J. F. de, XAVIER, M. L., FERNANDEZ, A. R., PINHAO, R., JANZ, G. J.,
QUEIROZ, J. S., CORREIA, М. € NEVES, S., 1966, Situacäo do foco de bilhar-
ziose do Algarve em 1966. Em publicacäo.

BARBOSA, F. S. & BARRETO, A. C., 1960, Differences in susceptibility of Brazilian
strains of Australorbis glabratus to Schistosoma mansoni. Exp. Parasitol., 9:
137-140.

ВЕМЕХ, J., 1965, Recherches sur l’infection expérimentale de tentacules de planorbes
en survie, par des miracidiums de Schistosoma mansoni. These, Paris.

CRISTO, М. I., 1968, Consideracdes sobre a posicäo sistemática de Bulinus (B.) con-
tortus (Michaud) de Portugal. - Em publicacáo. Carcia de Orta, Junta de Investi-
gacdes de Ultramar.

MANDAHL-BARTH, G., 1965, The species of the genus Bulinus, intermediate hosts of
Schistosoma. Bull. Org. Mond. Santé, 33: 33-44.

MEDEIROS, L. C. M. de, 1962, A proposito do morfologia do Bulinus (B.) contortus
de Portugal. - Apresentado ao Cong. Luso-Espanhol para o Progresso das Ciéncias,
Porto, Junho, 22-26, 1962.

MICHEJDA, J., 1958, Biochemical bases for the taxonomy of snails. I. Chroma-
tographic analysis of some fresh-water snails. Bull. Soc. Amis Sci. Lett., Poznan,
В 14 341-344.

34 PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

MICHEJDA, J. & TURBANSKA, A., 1958, Biochemical bases for the taxonomy of
snails. Ш. Differencesin chromatographic patterns of various organs and tissues.
Bull. Soc. Amis Sci. Lett., Poznafi, B 14: 362-365.

MICHEJDA, J. & URBANSKI, J., 1958, Biochemical bases for the taxonomy of snails.
II. An attempt at a chromatographic analysis of some species of snails. Bull.
Soc. Amis Sci. Lett., Poznan, B 14: 346-347.

TARGETT, G. A. T., 1963, Electrophoresis of blood from intermediate and non-
intermediate snail hosts of schistosomes. Exp. Parasitol., 14: 143-151.

WRIGHT, C. A., 1962, The significance of infra-specific taxonomy in bilharziasis.
Bilharziasis, Ciba Foundation Symposia, 103-112.

WRIGHT, C.A., 1964, Biochemical variationinLymnaea peregra(Mollusca, Basomma-
tophora) Proc. zool. Soc. Lond., 142: 371-378.

MALACOLOGIA, 1969, 9(1): 35-36
PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

FACTORS AFFECTING GROWTH AND REPRODUCTION OF
FRESHWATER PLANORBIDAE IN EAST AFRICA

A. D. Berrie
Department of Zoology, University of Reading, England
ABSTRACT

Information about the life cycles of freshwater pulmonate snails is not very extensive. Most studies have
been in the northern temperate zone where the snails tend to have simple annual cycles, but small species
may have more than one generation per year and large species may require more than a year for a single
generation (HUNTER, 1961; BERRIE, 1965). Growth proceeds rapidly under favourable conditions of tem-
perature and food supply and variation in these conditions and in endogenous factors causes differences
in the growth rates of populations in different habitats or of the same population in different years. Some
aspects of the maturation of the reproductive system are related to the size of the snails while other aspects
are associated with the time of year, and oviposition takes place when the snails are large enough and the
environmental conditions are favourable (BERRIE, 1966).

The planorbid snails which act as intermediate hosts of schistosomes in Africa are medium sized and,
in most parts of the continent, they are seldom subjected to low water temperatures. In these circum-
stances the snails might be expected to breed continuously maintaining the populations at a level determined
by the environmental resistance. Such a situation has never been reported presumabiy because some en-
vironmental factors undergo changes which affect the growth and reproduction of the snails.

Some of these factors have been investigated under laboratory conditions. The growth rates of Bulinus
globosus and Biomphalaria pfeifferi increase with rise intemperature but at temperatures of 30° C or over
there is a decline in survival and fecundity (SHIFF, 1964; STURROCK, R. F., 1966; SHIFF & GARNETT,
1967). The intrinsic rate of natural increase is greatest at about 25° C and both species are capable of
rapid population expansion at this temperature. Most laboratory studies have been carried out at constant
temperatures and experiments involving diurnal fluctuations comparable to those experienced in natural
habitats would be very useful. Infection with schistosomes affects the growth and fecundity of snails al-
though there is some variation in the effects which have been reported on growth. Infection of B. pfeifferi
causes a temporary increase in the growth rate which is proportional to the intensity of the infection but
survival and fecundity are reduced (STURROCK, В. M., 1966). When snails are maintained at high densities
in aquaria, their growth and fecundity are both reduced in proportion to the degree of crowding. This has
been demonstrated in several African planorbids but the causal mechanisms have not been identified.

In temporary pools in East Africa, populations of Bulinus nasutus and B. globosus build up very rapidly
under favourable conditions with high rates of growth and fecundity which can result in short life cycles
at such times (WEBBE, 1962; BERRIE, unpubl.). However, the great increase in population size combined
with the gradual decrease in the size of the habitats causes conditions to deteriorate. Populations of
Bulinus ugandae and Biomphalaria sudanica tanganyicensis in ditches in Uganda appear to have a simple
annual life cycle with a period of reproductive activity associated with the first rains (BERRIE, 1964).
At first the young snails grow quite rapidly, but the growth rate soon slows down until eventually growth
practically ceases for a considerable time prior to the next reproductive period. During most of the year
the populations consist mainly of snails which are large enough to become sexually mature, and the ab-
sence of reproductive activity must be attributedto adverse environmental conditions which change with the
start of the rains. There are a number of ways in which the rains could affect the snails, and the factors
which trigger the reproductive period cannot yet be identified. We know surprisingly little about the food
requirements of snail populations which may be one important factor.

A population of Biomphalaria sudanica tanganyicensis in a small pool in Uganda showed inhibition of
growth during five months when the population density was high (BERRIE, 1968). The density was dras-
tically reduced by collecting, and the water volume was simultaneously increased by rain. The remaining
snails immediately resumed rapid growth and a periodof reproductive activity followed. Water taken from
the pool during the period of growth inhibition was found to contain a soluble toxin capable of causing such
inhibition (BERRIE & VISSER, 1963).

The growth and reproduction of African planorbids often seem to vary and may be responding to a variety
of intrinsic and extrinsic factors. If these natural population regulators can be identified it should be pos-
sible to reach a fuller understanding of the dynamics of natural populations, and it may be possible to con-
sider new methods of controlling snail populations.

(35)

36 PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS
REFERENCES

BERRIE, A. D., 1964. Observations on the life-cycle of Bulinus (Physopsis) ugandae Mandahl-Barth, its
ecological relation to Biomphalaria sudanica tanganyicensis (Smith), and its role as an intermediate
host of Schistosoma. Ann trop. Med. Parasitol., 58, 457-466.

BERRIE, А. D., 1965. On the life cycle of Lymnaea stagnalis (L.) in the West of Scotland. Proc. malacol.
Soc. London, 36, 283-295.

BERRIE, A. D., 1966. Growth and seasonal changes in the reproductive organs of Lymnaea stagnalis (L.).
Proc. malacol. Soc. London, 37, 83-92.

BERRIE, A. D., 1968. Prolonged inhibition of growth in a natural population of the freshwater snail Biom-
phalaria sudanica tanganyicensis (Smith) in Uganda. Ann. trop. Med. Parasitol., 62, 45-51.

BERRIE, A. D. € VISSER, S. A., 1963. Investigations of a growth-inhibiting substance affecting a natural
population of freshwater snails. Physiol. Zoöl., 36, 167-173.

HUNTER, W. R., 1961. Life cycles of four freshwater snails in limited populations in Loch Lomond, with
a discussion of infraspecific variation. Proc. 2001. Soc. London, 137, 135-171.

SHIFF, C. J., 1964. Studies on Bulinus (Physopsis) globosus in Rhodesia. I. The influence of temperature
on the intrinsic rate of natural increase. Ann. trop. Med. Parasitol., 58, 94-105.

SHIFF, C. J. & GARNETT, B., 1967. The influence of temperature on the intrinsic rate of natural increase
of the freshwater snail Biomphalaria pfeifferi (Krauss) (Pulmonata: Planorbidae). Arch. Hydrobiol.,
62, 429-438.

STURROCK, В. M., 1966. The influence of infection with Schistosoma mansoni on the growth rate and repro-
duction of Biomphalaria pfeifferi. Ann. trop. Med. Parasitol., 60, 187-197.

STURROCK, БВ. F., 1966. The influence of temperature on the biology of Biomphalaria pfeifferi (Krauss),
an intermediate host of Schistosoma mansoni. Ann. trop. Med. Parasitol., 60, 100-105.

WEBBE, G., 1962. The transmission of Schistosoma haematobiuminan area of Lake Province, Tanganyika.
Bull. Wld. Hlth. Org., 27, 59-85.

MALACOLOGIA, 1969, 9(1): 37-38
PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS
AN IMMUNO-CYTOLOGICAL STUDY OF THE AFRICAN SUBGENUS BULINUS 3.3.1
J. В. Burch? and G. К. Lindsay
Museum of Zoology, University of Michigan, Ann Arbor, Michigan, U.S. A.
ABSTRACT

The planorbid genus Bulinus is found over most of the African continent where habitats are suitable for
freshwater pulmonate snails. The genus is also found on the East African islands and selectively in many
Mediterranean and Middle Eastern countries. The medical importance of the genus lies in the fact that
certain of its species are the intermediate hosts of human urinary bilharziasis.

The various bulinine species traditionally have been groupedinto 3 taxa (lately referred to as subgenera,
formerly as genera): Bulinus s.s., Physopsis and Pyrgophysa. It is the subgenus Bulinus s.s., comprising
the tropicus and truncatus species groups of MANDAHL-BARTH (1957, Bull. Wid. НИЙ. Org., 16: 1103-
1163), that is of special concern in the present study, because few of the taxa that have been established
within these 2 species groups currently can be defined with any precision in terms of the limits of mor-
phological variation and geographical distribution. Also, the validity of the 2 groups themselves has been
questioned. Yet, on both parasitological and cytological grounds, there do seem indeed to be 2 distinct
groups, that can be defined with some precision. The more northern truncatus group is polyploid and, as
far as known, is susceptible to infection with Schistosoma haematobium, either under natural or experi-
mental conditions. The more southern group is diploia and generally is not considered to be susceptible
to human schistosome infection.

Assigning species to the 2 groups has proven difficult for malacologists. For example, species that were
first placed with one group by Mandahl-Barth only to be shifted by him later to the other group are: Bulinus
guevnei, В. natalensis and В. sericinus. Characters that are currently being used to assign species to one
or the other of the 2 species groups in question are the shape of the mesocones of the first lateral teeth
of the radula, the degree of presence or absence of a male copulatory organ, and the shape of the shell.

Recently, it has been reported that the truncatus group, previously thought not to occur south of the great
African lakes, occurs as far south as South-West Africa and the Transvaal (MANDAHL-BARTH, 1965,
Bull. Wid. НИЙ. Org., 33: 33-44; SCHUTTE, 1965, Ann Mag. nat. Hist., 8: 409-419; 1966, Ann. trop. Med.
Parasit., 60: 106-113). This information isbased on the occurrence of Bulinus natalensis and В. depressus
in those regions and the fact that these 2 species apparently have “arrow-head shaped” mesocones on the
first lateral teeth of the radula, thought to be characteristic of the {гипса $ species group (in contrast
to the “triangular shaped” mesocones thought tobe characteristic of the tropicus species group). However,
В. natalensis has 18 pairs of chromosomes, a characteristic of the tropicus group (some В. natalensis
populations have one to several extra chromosomes), and, аз shown by the present study, this species also
shows immunological affinities with the tropzcus species group rather than the truncatus group.

In the present investigation the use of an immunological method employing the specific absorption tech-
nique enabled the observation of “identity” or “non-identity” between various of the 37 populations tested
against the 3 species for which there were antisera. The results (Table 1) show that there is good corre-
lation between serological tests and the chromosomal ploidy of the populations, and a lack of complete
correlation with characters of the radular mesocones, the single feature currently given the most impor-
tance for species group identification.

It is concluded from these results that (1) the subgenus Bulinus s.s. does indeed comprise more than
one species group, each of which can be identified cytologically, parasitologically and immunologically;
(2) little reliance can be placed on those morphological characters now being used to place a species into
its species group; and (3) in face of the intensive but unrewarding morphological research already devoted
to the genus, perhaps simple biochemical tests should be employed instead of morphological characters
by field workers attempting to ascertain the potential of natural populations for transmitting urinary
bilharziasis.

A more detailed account of these studies will be published in Malacological Review.

lSupported by a research grant (AI 07279) from the National Institute of Allergy and Infectious Diseases,
U.S. Public Health Service.

2Supported by a Research Career Program Award (No. 5-K3-AI-19,451) from the National Institute of
Allergy and Infectious Diseases, U.S. Public Health Service.

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PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

TABLE 1. “Non-identity” reactions, observed т the micro-Ouchterlony immunodiffusion
test, between antigens and antisera of various populations of Bulinus s.s.
| =
ее | | Haploid A eee el
lation N Bulinus County chromosome |
es rnishing antigen oa ane Ber Aer
antiserum |antiserum |antiserum
===} = u
1 B. sp. Senegal 18 ot = 2
2 B. sp. Senegal 18 о = £
3 B. sp. Ethiopia 18 = - 3+1
4 B. sp. Ethiopia 18 о - -
5 B. sp. Ethiopia 18 о 2 -
6 В. зр. Ethiopia 18 о 1772 ЗЕ
7 В. вр. + Ethiopia 18 2+2 3+1 2+1
8 B. tropicus alluaudi Kenya 18 о 3 3
9 B. tropicus tropicus Rhodesia 18 о 3+2 DEC
10 B. tropicus tropicus Rhodesia 18 о 2 2
11 B. tropicus tropicus Rhodesia 18 о 3 -
12 B. tropicus tropicus Rhodesia 18 о 2+2 -
13 B. tropicus tropicus Rhodesia 18 о 3+1 2+1
14 В. tropicus tropicus Rhodesia 18 о 2+1 2
15 В. tropicus tropicus Rhodesia 18 о 3+2 -
16 B. tropicus tropicus S. Africa 18 о 322 2
17 B. natalensis Rhodesia 18 о 3 -
18 В. natalensis Rhodesia 18 o 2 2
19 B. truncatus ssp. Corsica 36 3+1 о 2
20 В. truncatus truncatus | Iran 36 2+1 о 2
21 В. truncatus truncatus | Iran 36 РЕ о 2
22 B. truncatus truncatus | Egypt 36 3472 о =
23 В. truncatus truncatus | Egypt 36 3+2 о 2
24 В. truncatus truncatus | Sudan 36 2+2 о 2
25 В. truncatus ssp. W. Aden 36 2 о =
26 B. truncatus rohlfsi Mauritania 36 1+2 о =
27 В. truncatus rohlfsi Ghana 36 eres о 2
28 В. guernei Gambia 36 ZT о -
29 B. coulboisi Tanzania 36 3+ 2 о 3+1
30 В. coulboisi Tanzania 36 т +2 о -
31 B. coulboisi Tanzania 36 3+1 о -
32 B. sp. Ethiopia 54 2+2 - DEO
33 B. sp. Ethiopia 12 ТЕТ - -
34 В. зр. Ethiopia 72 2 cat - =
35 B. sp. Ethiopia 72 LEE 2 о
36 В. вр. Ethiopia 72 1+1 2+2 о
37 | В. sp. | Ethiopia 72 Sole es. | o

In terms of number and intensity of “non-identity” precipitation bands: 1 = weak; 2 =
medium; 3 = strong (3 + 2=two bands occurred, one strong and one medium in inten-

sity).

+ о= no “non-identity” reaction occurred

MALACOLOGIA, 1969, 9(1): 39
PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

THE INFLUENCE OF THE SUBSTRATUM ON POPULATION INCREASE AND HABITAT
SELECTION BY LYMNAEA NATALENSIS KRS. AND BULINUS (B.) TROPICUS KRS.
(MOLLUSCA, BASOMMATOPHORA)

C. Combrinck and J. A. van Eeden

Snail Research Group of the South African Council for Scientific and Industrial Research,
Zoology Department, Potchefstroom University, Potchefstroom, Republic of South Africa

ABSTRACT

In the course of anextensive survey ofthe freshwater snails in the Republic of South Africa it was noticed
that the most commonly occurring species were, inthe majority of cases, found to be associated with habi-
tats containing a muddy substratum. This posed the question whether the substratum, as such, was in any
way of critical importance in the selection and suitability of the habitat for the snails in question. Two
species viz. Bulinus (Bulinus) tropicus Krs. and Lymnaea natalensis (Krs.) and 5 different substratum types
were selected. Observations on these were made in an outdoor river model and in both out- and indoor
aquaria.

The criteria chosen for testing the suitability of the substratum were: (1) certain population statistics
such as survivorship (LS), reproduction rate (mx ), proportional egg curve (Vx) and nett reproduction rate
(Ве), from which the capacity for increase (r.) were calculated; (2) growth rate as reflected by weight in-
crease; (3) the ability of the snails to select a particular substratum type from a randomly distributed
series.

On the basis of the performance of the snails on each or the relative number of snails which visited each
substratum type under the conditions created the substratum types were, in each case, arranged ina so-
called success sequence. Some of the sequences arrived at are given in Table 1.

The behaviour studies revealed no definite active selection of any specific substratum type and the re
sequences arrived at is correlated with the abundance of microflora rather than with increasing or de-
creasing particle size of the substratum type. Under the conditions prevailing in our experimental setup
our results therefore seem to have been determined by the availability of suitable food rather than by a
direct affect of the substratum.

TABLE 1. Performance of Lymnaea natalensis and Bulinus tropicus on five different substratum types
where M = mud, K = stones, S = sand, G = gravel and Fs = fine sand

| Success sequence
Species Item — € A A —
1 2 3 4 5
Te M > к > 5 SIG = Fs
L. natalensis
Growth rate M > K > 5 > а > Fs
Te K = Fs = M = 5 > а
В. tropicus
Growth rate M > K > 5 > Fs > G
L. natalensis
and Microflora M > K > 5 > а > Fs
В. tropicus |

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MALACOLOGIA, 1969, 9(1): 40-41
PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS
THE PRESENT STATUS OF BILHARZIASIS IN THE DOMINICAN REPUBLIC
Frank J. Etges and Jose F. Maldonado

Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, U. S. A.
Department of Medical Zoology, School of Medicine, University of Puerto Rico

ABSTRACT

Relatively few reports have been published concerning prevalence and distribution of Schistosoma mansoni
and its molluscan vectors in the Dominican Republic. The parasite was first reported in this country by
PONCE PINEDO (1945), who also identified the town of Hato Mayor as the endemic focus (1947). OLIVIER,
VAUGHN & HENDRICKS (1952) confirmed that Hato Mayor was the primary focus of transmission, and
reported an incidence of 21.4% in children, with approximately equal frequency in boys and girls. Follow-
ing chemical treatment of the stream Pafia Pafia and several tributaries, VAUGHN et al. (1954) reported
successful elimination of snails from the area; no snails were found in the 6 month period immediately
after a single application of sodium pentachlorophenate at 15 ppm. While it is uncertain when the popula-
tion of Biomphalaria glabrata recovered from this treatment, one of us (FJE) noted a very large population
in Pafia Pafia stream in July, 1959. MALDONADO (1962) reported an overall positivity to the Bilharzia
Skin Test of 30% in school children in Hato Mayor, with boys showing the highest rate (46%).

On the basis of evidence gathered in 6 surveys made during 1963-68, it is apparent that Biomphalaria
glabrata is far more widely distributed in the Dominican Republic than previously reported. Five well-
established populations are located as follows: the Rio Magua drainage system, including Pafia Pafia
stream, around Hato Mayor; the swamps and stream in the town of Miches; irrigation canals of the Rio
Cuarón near the town of Nisibón, east of Miches; extensive rice-fields and irrigation canals surrounding
the town of Cotuf in the central valley; and a large swamp 9 km. from the northern town of Nagua. These
foci are separated by distances of up to 240 km., and establish a range of approximately 1/6 the total area
of the Dominican Republic. Tropicorbis riisei, another planorbid species, is far more widely dispersed,
from the Haitian border to the east end of the island and from the north to the south coast. Unlike B.
glabrata, T. riisei is practically continuously distributed in all fresh-water habitats.

Surveys for human cases of Schistosoma mansoni infection, using the standard adult antigen intradermal
test and direct fecal examination, have confirmed the continuing high rate of transmission in Hato Mayor.
In other localities where Biomphalaria glabrata was found, our findings were essentially negative. One
equivocal finding of 22% positive intradermal reaction among a group of school-age boys was contra-
dicted by negative fecal examinations. It is suggested that this group may have shown false-positive skin
test reactions by cross-reaction to avian-mammalian cercarial exposure, a phenomenon recently demon-
strated by MOORE, et al (1968).

In 1963, Pafia Pafia stream and collateral bodies of water in the area of Hato Mayor were seeded with
about 1750 specimens of Marisa cornuarietis; this snailhas been suggested as an effective biological control
agent in Puerto Rico by RADKE, RITCHIE & FERGUSON (1961). In the ensuing 5 years, periodic sur-
veillance has shown that the snails were washed downstream for several kilometers, but have returned to
Hato Mayor and established a very dense population in the Rio Magua since July 1967. This stream, into
which Paña Paña drains, was only partially inhabited by the upstream-migrating М. cornuarietis popula-
tion; consequently one portion of the stream has an undisturbed Biomphalaria glabrata population, another
portion of about 1.5 km. length has numerous М. cornuarietis and practically по В. glabrata, and a third
zone of about 500 m contains both species overlapping. Presumably the latter zone represents the level
to which M. cornuarietis has migrated, and where time and numbers have not been sufficient to inhibit the
existing B. glabrata population, as has apparently happened further down-stream.

The recent finding (1968) of an apparently newly introduced population of the Oriental snail, Tarebia
granifera, in the vicinity of Nisiboñ has introduced yet another complicating factor into the problem of Do-
minican snail population interactions. T. granifera, most probably introduced from Puerto Rico, is believed
to inhibit natural populations of Biomphalaria glabrata there, but the mechanism of inhibition is uncertain.
The manner of introduction even into Puerto Rico is unknown, but it appears to have been a natural event
in the Dominican Republic, judging from the extremely remote area in which it has been first found.

Because of the generally uncontrolled situation in the Dominican Republic, with respect to Bilharziasis,
continued surveillance of known populations of Biomphalaria glabrata, Marisa cornuarietis, and Tarebia
gvanifeva and extended surveys for snails and Bilharziasis are contemplated. As pointed out by OLIVIER,
VAUGHN & HENDRICKS (1952), the Dominican Republic was (and remains) a favorable situation for such
studies. In addition to the potential threat of spreading in this country, Bilharziasis in this area is of
biological and epidemiological interest as the northwestern-most extent of the range of neotropical Schisto-
soma mansoni and its molluscan vector, B. glabrata.

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ETGES and MALDONADO 41
REFERENCES

MALDONADO, J. F., 1962. Encuesta sobre esquistosomiasis en la poblacion de Hato Mayor, a base de la

intradermoreaccion. Unpublished report to Ministry of Health, Dominican Republic.

MOORE, G. T., KAISER, В. L., LAWRENCE, В. S., PUTNAM, 5. M., € KAGAN, I. G., 1968. Intradermal
and serologic reactions to antigens from Schistosoma mansoni in schistosome dermatitis. Amer. J.
trop. Med. & Hyg., 17: 86-91.

OLIVIER, L., VAUGHN, C. M. & HENDRICKS, J. R., 1952. Schistosomiasis in an endemic area in the Do-
minican Republic. Amer. J. trop. Med. & Hyg., 1: 680-687.

PONCE PINEDO, A. M., 1945. Seis casos autoctonos de esquistosomiasis de Manson. Congr. Med. Domini-
cano del Centenario (1944): 382-390.

PONCE PINEDO, А. M., 1947. Esquistosomiasis de Manson en Santo Domingo. Puerto Rico J. pub. НИЙ.
& Trop. Med., 22: 316-324.

RADKE, М. G., RITCHIE, Г. 5. & FERGUSON, Е. F., 1961. Demonstrated control of Australorbis glabratus
by Marisa cornuarietis under field conditions in Puerto Rico. Amer. J. trop. Med. € Hyg., 10: 370-373.

VAUGHN, C. M., OLIVIER, L., HENDRICKS, J. R. & MACKIE, T. T., 1954. Mollusciciding operations in
an endemic area of schistosomiasis inthe Dominican Republic. Amer. J. trop, Med. € Hyg., 3: 518-528.

MALACOLOGIA, 1969, 9(1): 42
PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

DIE BIOTOPE DER LEBEREGELSCHNECKE (GALBA TRUNCATULA)
UND IHRE BESIEDLUNG

W. Hohorst
Parasitologisches Institut der Farbwerke Hoechst AG, Frankfurt/M., D. В. В.
ZUSAMMENFASSUNG

Im Entwicklungskreislauf des “Grossen Leberegels” (Fasciola hepatica) ttbernehmenStisswasserschnecken
aus der Familie Lymnaeidae (Schlammschnecken) die Rolle des Zwischenwirtes. Obwohl sich aber viele
einheimische Schlammschnecken-Arten experimentell infizieren lassen, ist Galba truncatula der einzige
nattirliche Zwischenwirt in Europa. Der Hauptgrund ftir diese Tatsache ist nicht zuletzt den besonderen
Lebensgewohnheiten dieser Schnecke zuzuschreiben.

Galba truncatula ist amphibisch lebend und findet nochin den kleinsten Wasseransammlungen ausreichende
Lebensbedingungen, wodurch sie mit Weidetieren (Rinder, Schafe), den hauptsächlichsten Endwirten des
Leberegels, in besonders engen Kontakt kommt. Aber auf welche Weise erfolgt die Besiedlung dieser oft
völlig isolierten Biotope? Untersuchungen zur Verbreitung von Galba truncatula in der Umgebung von
Frankfurt am Main, die seit 1932 durchgeführt werden, gaben Gelegenheit, auch diese Frage zu untersuchen.

In der Umgebung von Frankfurt am Main ist Galba truncatula allgemein verbreitet. Man findet sie aber
fast ausschliesslich nur im offenen Gelände, und ihre bevorzugten Lebensräume sind Entwässerungs-
gräben von Wiesen oder Weiden, sowie Strassengräben und Quelltümpel. Meist handelt es sich um kleine
und kleinste Wasseransammlungen, deren Wasserstand sehr starken jahreszeitlichen Schwankungen, in
Abhängigkeit von den anfallenden Niederschlagsmengen, ausgesetztist. Diese Fundplätze trocknen gelegent-
lich völlig aus, und die Siedlungsdichte ihrer Populationen wechselt daher ständig. Manchmal erlöschen
solche Fundplätze vollkommen, können aber unter Umständen eines Tages wieder neu besiedelt werden.
Grössere Gewässer wie Bäche oder Tümpel werden von Galba truncatula nur in den äussersten Randzonen
besiedelt. Solche Fundplätze sind sehr anfällig gegen Hochwasser und daher gewöhnlich nur von kurzer
Lebensdauer.

Von anderen Schlammschneckenarten, die mit Galba truncatula am gleichen Fundort vergesellschaftet
sind, findet sich nördlich des Main-Flusses nur Radix peregva. Südlich des Mains findet man dagegen
Radix peregra und Galba palustris, gelegentlich auch Galba glabra und Lymnaea stagnalis. Eine sichere
Unterscheidung mancher dieser Arten nach der Gehäuseform ist, besonders bei kleineren Exemplaren,
häufig sehr schwierig, liess sich aber nach dem Bau der Geschlechtsorgane stets eindeutig durchführen.
Bei Galba palustris zeigten sich Übereinstimmungen mit den von Jackiewicz (1959) für “Galba corvus”
beschriebenen Verhältnissen.

Die Untersuchungen über die Besiedlung der Fundplätze durch Galba truncatula für die Verhältnisse der
Umgebung von Frankfurt am Main haben zu folgenden Ergebnissen geführt. Bei den meisten Fundplätzen
erfolgt die Besiedlung durch Verschwemmung von lebenden Schnecken aus dem Oberlauf der Gewässer,
besonders bei Hochwasser. Bei anderen Fundplätzen, insbesondere bei solchen, die an der äussersten
Peripherie, d.h. in den Quellbezirken von Bachsystemen gelegen sind oder die völlig vom Wasserzulauf
isoliert sind, ist eine solche Art der Besiedlung nicht möglich. Hier könnte man an die Möglichkeit einer
Besiedlung durch Verschleppung von Schnecken durch Vögel denken, worauf in der Literatur schon mehrfach
hingewiesen worden ist. An einem Fundort besonderer Art, es handelt sich um die gemauerten Wasser-
becken eines Friedhofs, aus denen die Besucher das Wasser zum Blumengiessen schöpfen, konnte nachge-
wiesen werden, dass Galba truncatula durch Wasserkäfer verschleppt werden kann.

Die Untersuchungen über die Besiedlung von natürlichen Fundplätzen bei Galba truncatula wurden durch
Beobachtungen an einem künstlichen Grabensystem in einem Versuchsgarten unseres Institutes ergänzt.
Hierbei konnte nachgewiesen werden, dass Galba truncatula rheotaktische Bewegungen ausführt. Mar-
kierte Schnecken krochen in dem Grabensystem gegen die Strömungsrichtung des Wassers und überwanden
hierbei mühelos sogar mehrere vom Wasser nur schwach überrieselte Steinstufen. Innerhalb von 24
Stunden wurden Strecken von 4 Meter und mehr zurückgelegt. Da Galba truncatula an vielen natürlichen
Fundorten ständig einer Verschwemmung durch das fliessende Wasser ausgesetzt ist, kommt den rheotak-
tischen Bewegungen eine hohe Ökologische Bedeutung zu. Auf diese Weise kann die Wiederbesiedlung der
Fundplätze auch gegen die Strömungsrichtung erfolgen und Galba truncatula kann aus eigener Kraft bis in
die äussersten peripheren Bezirke von fliessenden Wassersystemen vordringen, wo sich ihre bevorzugten
Biotope befinden.

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MALACOLOGIA, 1969, 9(1): 43
PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

AEROMONAS LIQUEFACIENS IN THE LEUKODERMIA
SYNDROME OF ACHATINA FULICA

Albert R. Mead
University of Arizona, Tucson, Arizona, U. S. A.
ABSTRACT

Populations of the giant African snail, Achatina fulica, in the Indo-Pacific region manifest a frank, en-
zootic disease syndrome. Coincident with the development of the disease in the older populations, there
appears a predictable, statistically significant progressive population decline that may ultimately result
in localized extinction. A Gram-negative rod bacterium repeatedly has been isolated at a statistically
significant level from the leucodermic lesions and from the abundant terrestrial isopod Metoponorthus
pruinosus, which is frequently found in close association with the giant snails. Through methods of deter-
minative bacteriology and techniques of serology, immunochemistry and fluorescine isothiocyanate con-
jugates, this bacterium has been identified as Aeromonas liquefaciens (Family Pseudomonadaceae), here-
tofore found only in aquatic vertebrates. The bacteria apparently do not act alone in producing the observed
enzootics, but act in concert or seriatim with other extrinsic and intrinsic stress factors. An endotoxin,
lethal both to snails and mice, has been demonstrated in this bacterium. Possible coincident or pre-
cursory viral parasitemia may exist as a complicating factor; however, introducing tissue homogenates
from infected snails into established tissue cultures of A. fulica on specially modified basic media have
so far proven inconclusive. It is believed that when molluscan pathology is more fully comprehended,
there will emerge more convincing explanations of natural fluctuations of snail populations and more effec-
tive population control of harmful species. (This research was supported by grant AI-01245 from the
National Institute of Allergy and Infectious Diseases, U. S. Public Health Service, and grant GB-2463 from
the National Science Foundation, Washington, D. C., U.S. A.)

MALACOLOGIA, 1969, 9(1): 43
PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS

THE ULTRASTRUCTURE OF THE DIGESTIVE GLAND CELLS OF
BIOMPHALARIA PFEIFFERI KRAUSS, AN INTERMEDIATE HOST
OF SCHISTOSOMA MANSONI SAMBON

Elisabeth A. Meuleman
Zoological Department, Free University, Amsterdam, The Netherlands
ABSTRACT

Mature daughter sporocysts of Schistosoma species are living mainly in the interstitium of the digestive
gland of the host snail.

Obviously, the function of the digestive gland and the mid-intestine determines this predilection-site. It
seemed interesting to investigate with the electron-microscope, together with other histological and histo-
chemical methods, the organs and tissues in the area concerned of normal, starved and parasitized snails.
As an experimental animal Biomphalaria pfeifferi (Pulmonata, Planorbidae) was chosen. In the present
paper the fine structure of the digestive gland of adult, unparasitized snails is described and the function
of the different cell types is discussed. The observations indicate that the main functions of the digestive
gland epithelium of Biomphalaria pfeifferi are: intracellular digestion, production and secretion of
enzyme granules and excretion of waste products.

Presumably the gland is not important as a storage-organ for reserve-material. At the ultrastructural
level the amount of glycogen in the gland epithelium is very small when compared to that in certain other
cells of the body. Therefore, very probably, the preference of the daughter sporocysts to live in the inter-
stitium is not related to a supposed storage function of the digestive gland, but rather to the fact that in
this area intracellular digestion and absorption take place, rendering the blood very rich in soluble food
materials.

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MALACOLOGIA, 1969, 9(1): 44
PROC. SYMP. MOLL. AS PARASITES OR THEIR TRANSMITTERS
THE CONTROL OF SCHISTOSOME DERMATITIS IN THE GREAT LAKES REGION (U. S. A.)
Henry van der Schalie
Museum of Zoology, The University of Michigan, Ann Arbor
ABSTRACT

Dr. У. У. Cort (1928) first demonstrated that “swimmers’ itch” or schistosome dermatitis was caused
by the penetration of non-human schistosome cercariae into the bodies of persons who waded or swam in
certain freshwater lakes. In recent years this human nuisance has increased considerably, so that for
each of the past 2 years at least 100 lakes in Michigan were reported to have had outbreaks of swimmers’
itch.

For many years the Water Resources Commission in Michigan each summer has employed high school
teachers to work as “itch crews” - teams of men to assist resort and cottage owners in eradicating in-
fected snails found on their beaches. Although copper sulphate is still used extensively, better and more
sophisticated methods are being developed, such as the application of Bayluscide sprayed over lakes by
airplane.

It has long been recognized that reasonably good control methods will be impossible without methods for
eradicating snail intermediate hosts. These problems are very involved since there are known to be at
least a dozen itch-producing non-human schistosomes in the Great Lakes region. The snails (2 Lymnaeids
and 1 Physa) at present incriminated and responsible for most of the schistosome dermatitis in Michigan
were studied some 30 years ago by Drs. Donald McMullen and Paul Beaver. Recent studies indicate that
conditions have changed and anewappraisalisnecessary to determine which snails are at present involved,
their ecology in relation to schistosome dermatitis infestation, and what methods should be recommended
for their control.

(44)

PROCEEDINGS

of the

THIRD EUROPEAN MALACOLOGICAL CONGRESS

(Vienna, 4-6 September 1968)

сна 99840 »

30 i

MALACOLOGIA, 1969, 9(1): 47-51

PROC. THIRD EUROP. MALAC. CONGR.

BIOLOGY AND POPULATION DYNAMICS OF TWO SYMPATRIC SPECIES
OF NERITINA FROM SOUTHERN NIGERIA!

O. S. Adegoke, T. F. J. Dessauvagie and V. L. A. Yoloye

University of Ife, Ibadan, University of Ibadan, Ibadan, University of Lagos,
Lagos, Nigeria

INTRODUCTION

Two polymorphic, partially sympatric species of Neritina inhabit the shallow marginal
lagoons and estuaries of southwestern Nigeria (Fig. 1). The commonest, Neritina
glabrata Sowerby, 1849, has a small (1-7 mm) shell, beautifully and variously banded,
lineated and spotted with white, black and red against a yellow background (Fig. 2).
The other, Neritina п. sp. is larger (about 12 mm), higher spired, and similarly banded,
lineated and spotted, but in adrab combinationof dark grey and brown colours (Fig. 3).

In the present study, specimens of both species were collected from seven stations
in the western Nigeria lagoon between Epe in the east and Badagri in the west.

THE WESTERN NIGERIAN LAGOON

The ecological setting of the coastal lagoons of southern Nigeria has been the sub-
ject of several detailed studies (Webb, 1958; Oianiyan, 1961; Sandison, 1966, 1966a;
Sandison and Hill, 1966; Hill, 1967; Hill and Webb, 1958). The salient features are
summarized below.

The Western Nigerian lagoon is the largest of the lagoon systems of the Guinea
Coast. It stretches for about 160 miles from Cotonou to the western edge of the Niger
Delta (Webb, 1958, p. 310). Several large rivers drain into the lagoon in the area
studied, the most important being the Yewa, Ogun, Ona and Oshun rivers. Besides,
the lagoon makes contact with the sea at Lagos and Cotonou. These factors make this
stretch of the lagoon sites of ecological interest because of the major fluctuations in
Salinity observed. These diurnal and seasonal fluctuations are the result of the inter-
play of tidal effects and the influx of large volumes of fresh water during the rainy
months.

The data published by Hill and Webb (1958) for Ikoyi jetty are shown in Fig. 4. The
salinity of the lagoon is highest between December and May, and from August to Sep-
tember. These correspond to the dry months. The excessive rains between March
and June, September and November, are primarily responsible for the low lagoon
salinity between June and July, October and November.

REPRODUCTION

The breeding cycle of both species is closely linked with the seasonal fluctuations
in the lagoon salinity. Eggs are laid primarily between February and March at the
peak of the high salinity season. Fertilization is internal and eggs are enclosed in
an agglutinated egg capsule (Fig. 5).

Lrhis work was supported by a grant to O. S. Adegoke from the Research Fund of the University
of Ife, Nigeria. The authors thank Professor C. I. O. Olaniyan of Lagos University for per-
mission to use the boat and laboratory facilities in his department.

(47)

48 PROC. THIRD EUROP. MALAC. CONGR.

T > T ar = se % =
o
a
$
0 «5
> gOtta 8,0
e S
dl
| ‘
О
Agege О Ikorodu
0 | Ikeja D
Ado
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o
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0 5 10 15 kilometres O Neriting п. sp.
1 Badagri 5 Ikoyi jetty
2 Iddo 6 Kuramo Water
3 University of Lagos 7 Ikorodu
4 Oworonsoki

FIG. 1. Map of southwestern Nigeria showing sampled localities and the distribution of Neritina
glabrata and Neritina п. sp.

FIG. 2. A few of the colour variations seen in Neritina glabrata.

FIG. 3. Neritina п. sp. showing range in coloration of shell.

ADEGOKE, DESSAUVAGIE and YOLOYE 49

»
о

salinity “fee

>
о

J: F. М. А. М. J- Jy: A. 5. O. М. О.
months

FIG. 4. Typical annual fluctuation in lagoon salinity at high and low tides (after Hill & Webb,
1958).

Each egg capsule is uniformly hemisphaerical with an ovate outline. Average di-
ameter is between 0.5 and 1.5 mm. The capsule wall is composed of quartz grains
with occasional amphibolite embedded in a matrix of chitin which also lines the floor
of the capsule. The basal wall of the capsule lacks agglutinating material and is com-
posed primarily of dense chitin. Collapse of the capsule occurs above this dense
chitinous base during hatching. The two species show preference for sand grains of a
particular size grade. Capsules of Neritina glabrata,though smaller, bear larger sand
particles (Fig. 5). The new species, however, utilizes grains that are barely percep-
tible at a magnification of over 80 times. As many as 6 to 17 eggs may be present in
each capsule of Neritina glabrata. Neritina new species sometimes has over 30 eggs
in one capsule. The eggs develop during the low salinity months between April and
December. The veliger stage is passed in the capsule.

The pediveligers are mechanically released from the capsules in January at the
high salinity season. The capsules break above the basal chitinous rim. Released
pediveligers are about 0.13 mm high.

LARVAL BEHAVIOUR

Larval activity and substrate selection were observedby artificially hatching mature
capsules of Neritina glabrata with a scalpel in a watchglass under a binocular micro-
scope.

Newly released larvae remain quiescent (except for slow ciliary action) for
periods varying between one and five minutes. Contact with saline water is a pre-
requisite for the initiation of active swimming movements. There is a sudden burst of
activity as the cilia of the two velar lobes begin to beat vigorously. Soon the larvae

50 PROC. THIRD EUROP. MALAC. CONGR.

swim off, round and round, one after the other. As they swim (aperture upwards) they
perform clockwise gyratory movements punctuated at short intervals by passive drops

x substratum

FIG. 5. Egg capsule of Neritina glabrata. Actual specimen is about 1 mm long.

to the bottom. The rapidity of “take-off” is enhanced by highly saline waters. Itis
slower in diluted brine. Larvae hatched and immersed for considerable periods in
distilled water are physiologically retarded and fail to recover fully when transferred
into more saline water. Such larvae were incapable of active swimming.

The pediveligers settle inthe protected niches afforded by closely packed sand grains
or in hollows and depressions on wood. When a site is selected, the gyratory move-
ment ceases and the larva feeds actively. When dislodged from a selected site, the
gyratory (Sampling) movements are resumed until another suitable site is found. The
examined larvae retained the ability to swim actively when disturbed for about 2-3
days at the end of which a thin golden shell has been secreted (veliconch).

ECOLOGY AND POPULATION STUDIES

Neritina glabrata and Neritina new species are partially sympatric. The former
lives primarily in the lagoon bottom sand but may also creep on concrete walls and
metallic supports of jetties. The species shows a preference for clean coarse sand
with little or no organic decay. It was rare in the stiff, fine silty sand of Lighthouse
and Badagri Creeks. Specimens of the new species on the other hand are found attached
to mangrove roots, walls and water plants but never in the bottom sand. Thus, at
all sympatric locations the two species are ecologically differentiated; interspecific
competition thus seems to be absent.

Both species are abundant at a number of locations. Neritina glabrata is commonest
at Ikoyi and part of Kuramo Water. Its average population density at Ikoyi during the

ADEGOKE, DESSAUVAGIE and YOLOYE 51

breeding season is about 20 per squarefoot. The density decreases appreciably during
the low salinity months. Highest density and maximum size of Neritina new species
was at the west end of Kuramo Water and at Badagri. Where both species live sym-
patrically, (e.g., Ikoyi, Oworonsoki, Ikorodu and part of Kuramo Water) Neritina
glabrata outnumbers the new species and both rarely attain maximum adult size.

REFERENCES

HILL, М. B., 1967. The Life Cycles and salinity tolerance of the serpulids Mercierella
enigmatica Fauvel and Hydroides uncinata (Philippi) at Lagos, Nigeria. Jour.
Anim. Ecol., 36, pp.303-321, 8 figs.

HILL, M. B. & WEBB, J. E., 1958. The ecology of Lagos Lagoon. II. The topography
and physical features of Lagos Harbour and Lagos Lagoon. Phil. Trans. Roy. Soc.,
London, ser. B, no. 683, 241, pp. 319-333, pl. 14, 6 figs.

OLANIYAN, C. I. O., 1961. Observations on the salinity and stratification of tidal
currents in Lagos Harbour, Nigeria. J. West Afr. Sci. Assoc., Т, рр. 49-58.

SANDISON, EYVOR E., 1966. The effect of salinity fluctuations on the life cycle of
Balanus pallidus stutsbuvi Darwin in Lagos Harbour, Nigeria. J. Anim. Ecol.,
35 pp. 363-378, 8 figs.

SANDISON, EYVOR E., 1966a. The effect of salinity fluctuations on the life cycle of
Gryphaea gasar (Adanson Dautzenberg) in Lagos Harbour, Nigeria. Jour. Anim.
Ecol., 35, pp. 379-389, 5 figs.

SANDISON, EYVOR E. & HILL, M. B., 1966. The distribution of Balanus pallidus
stutsburi Darwin, Gryphaea gasar (Adanson) Dautzenberg, Mercierella enigmatica
Fauvel and Hydroides uncinata (Philippi) in relation to salinity in Lagos Harbour
adjacent creek. Jour. Anim. Ecol.,35, pp. 235-250.

SOWERBY, С. B., 1849. Thes. Conch. I. по. 10, р. 535.

WEBB, J. E., 1958. The ecology of Lagos Lagoon I. The Lagoons of the Guinea Coast.
Phil. Trans. Roy. Soc. Lond., ser. B. no. 683, 241, pp. 307-318, pls. 11-13, 3 figs.

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MALACOLOGIA, 1969, 9(1): 53-57

PROC. THIRD EUROP. MALAC. CONGR.

UBER DIE VERBREITUNG DER LAND- UND SUSSWASSERSCHNECKEN
IN MITTELSPANIEN IN BEZUG AUF DIE VERSCHIEDENEN BODEN
UND GEWASSER

J. Alvarez
Department of Zoology, University of Madrid, Spain
ZUSAMMENFASSUNG

Obwohl diese Mitteilung im allgemeinen nicht auf Grundvon Analysen, sondern
nur durch empirische Beobachtungen erarbeitet wurde, ist sie ganz tibereinstim-
mend mit den Angaben einer anderen Arbeit. Die Analysen dieser Arbeit zeigen
uns ohne Zweifel, dass im allgemeinen doch ein grosser Einfluss der Böden und
Gewässer mit einem hohen Kalzium-Gehalt auf die Verbreitung der Schnecken
besteht. Dieser Einfluss ist aber nicht bei jeder Art von gleicher Bedeutung.
Manche Wasserschnecken können (experimentellerweise oder in der Natur) ohne
Kalzium leben. Die von FRÖMMING (1956) erwähnten Beispiele auf S. 34 seines
Buches, dass der Härtegrad (oder Kalkgehalt) eines Wohngewässers für die
Schnecken keine Rolle spielt, gibt uns auch Anlass zu glauben, dass die ver-
schiedenen Arten nicht immer gleich in bezug auf den Kalkgehalt des Milieus
reagieren; der Einfluss anderer Faktoren kann die Physiologie verändern und
anderseits kann es auch möglich sein, dass bei Wasserschnecken vor allem
unter bestimmten Umständen das Kalzium nicht aus dem Wasser direkt ent-
nommen wird, sondern nur auf indirekte Weise mit der Nahrung (Pflanzen) aus
dem Boden.

VORWORT

Der Anteil an Schneckenarten in bezug auf die ganze Molluskenfauna ist in Mittel-
spanien sehr gering. Im Vergleich mit anderen Regionen, wo man nicht nur grosse
Massen von Schnecken finden kann, sonder auch viele verschiedene Arten, ist die
Umgebung der Stadt (etwa 60 km um Madrid) von diesen Tieren fast unbewohnt. Wenn
man nun auf den Gedanken kommt, dass in jedem Bezirk Spaniens, wo der Boden
kalkig ist, viele Schnecken vorkommen, wenn man dabei noch weiss, dass diese Tiere
grosse Mengen von Kalziumkarbonat benötigen um ihre Gehäuse zu entwickeln, kann
man leicht daraus folgern, dass diese Mollusken direkt vom Boden das Kalzium ent-
nehmen können, und daher ein Mangel oder Fehlen dieses Stoffes im Boden die Selten-
heit oder das Verschwinden der Schnecken bedingt.

So kamen wir zu dem Schluss, die Beziehungen zwischen Böden (oder Gewässer)
und Schnecken in Mittelspanien näher zu studieren.

KURZE GEOLOGISCH-EDAFISCHE BESCHREIBUNG
DER BÖDEN IN MITTELSPANIEN

Die Böden der Umgebung von Madrid bestehen hauptsächlich aus Sedimenten des
Tertiärs (Miozin). Die Verteilung derselben ist innerhalb 60 km um die Stadt so,
dass man insgesamt von 5 Stufen reden muss, die sich von NO nach SW erstrecken
und von verschiedener Breite sind. Der Verlauf ist fast parallel zum benachbarten
Gebirge. Die 1. Stufe besteht aus Granit oder Gneis und steigt bis auf Höhen von
2.400 m. Das echte Bergland fängt schon mit 1.100 m.H.an. Es ist teilweise mit
Kiefernwald bedeckt.

(53)

54 PROC. THIRD EUROP. MALAC. CONGR.

Die 2. Stufe ist eng und unterbrochen; sie besteht aus 4 Flecken von Kalkstein der
Kreidezeit. Die Pflanzenwelt ist sehr spärlich undbesteht hauptsächlich aus Thymus -
Arten.

Die nächste Stufe (1. aus Flöz) ist aus einer Mischung von grobem Quarzsand und
Kalk-Tonerde entstanden; sie erstreckt sich am Fusse des Gebirges in Höhen zwischen
1.100 und 900 m. Die Flora diese Geländes besteht vorwiegend aus Gebüsch von Wach-
older und Cistus-Arten. An feuchten Stellen sind aber andere Pflanzen zu finden wie
Pappeln, Eschen, Wildrosen usw.

Die 4. Stufe besteht aus Kieselsand und Tonerde; sie ist breiter als die vorher-
gehende und dehnt sich über ein Gelände inungefähr 700 m. Höhe aus, in dem die Stadt
Madrid liegt. Der Pflanzenbewuchs ist sehr verschieden; an Flüssen und anderen
Gewässern sind Binsen, Schilfrohr und Rohrkolbenarten sehr häufig sowie Eschen,
Pappeln und Weiden. An trockenen Hügeln findet man Wintereiche und Retama
sphaerocarpa (Lam.) (Ginsterart). Stellenweise sind auch Kulturpflanzen zu finden.

Die 5. Stufe liegt am tiefsten; sie besteht aus Tonerde und erstreckt sich besonders
die Flusstäler entlang. An manchen Stellen, südöstlich der Stadt, erscheinen Flecken
einer dicken Schicht von Gipsgesteinen, die ein Ödes, steppenartiges Gelände verur-
sachen, das sich in einer Höhe zwischen 600 und 400 m. und in einem Areal von un-
gefähr 40 qkm erstreckt.

ÖKOLOGISCHE ÜBERSICHT DER GEWÄSSER

Die fliessenden und stehenden Gewässer des untersuchten Bezirkes müssen, in
bezug auf die Ökologie der betreffenden Mollusken, infolgende Gruppen eingeteilt wer-
den: (1) Bergland, fliessende oder stehende Gewässer auf Granitboden, über 1.200 m.
(2) Dieselben unter 1.200 mbisauf 900 m Höhe. Dieselben wie letztere aber auf Kalk-
steinboden. (3) Stehende oder fliessende Gewässer der Ebene (oder Hügelland) von
900 bis 500 m Höhe. (a) Auf Tonerde mit Sand und Kalk; (b) Auf Tonerde mit sehr
wenig Sand; (c) Aufechter Tonerde; und (d) Auf salzigen oder gipsigen Böden.

Grosse oder kleine Wasserflächen der verschiedenen Typen, die nicht beständig
sind, kommen im allgemeinen für Mollusken nicht in Frage. Die Gewässer über
1.200 m oder vielmehr über 1.500 m, haben immer wenige oder keine Pulmonaten.
Die unter 1.200 m liegenden haben immer dieselben Arten, В. peregra (Müll.) Physa
acuta Drap. und Ancylus costulatus Küst., letztere fast nur in Bächen mit einer
starken Strömung. Man kann gut beobachten wie die Gewässer, je tiefer ihre Lage ist,
reicher an Individuen der erwähnten Arten werden und dabei auch andere Arten vor-
kommen, aber nur da wo Gehalt an Kalziumkarbonat reicher ist. Diejenigen, die sich
auf Kalkstein befinden, haben bei einer Höhe von 900 m. grosse Mengen von Individuen
der erwähnten Physa und Lymnaea Arten und weitere 5 Arten. Gewässer unter 900 m
haben immer Gastropoden. Die Pulmonata sind dabei reich vertreten. Bei salzigen
oder gipshaltigen Gewässern sind R. auricularia (L.)undvielfach auch Ph. acuta Drap.
zu finden, jedoch nur, wenn das Wasser kein Kochsalz enthält. Die Planorbidae sind
nur in reinen, Kalten und fliessenden Gewässern auf Sand mit Kalk heimisch.

Die 8 Arten, die in Mittelspanien zu finden sind, kommen viel zahlreicher in der
Ebene als im Gebirge vor. Einige sind aber doch nur Bewohner von Gebirgsbächen und
Quellen des Hügellandes.

WICHTIGE, NICHT EDAFISCHE, IN DER VERBREITUNG
NEGATIV WIRKENDE FAKTOREN

Man kann sagen, dass die Trockenheit der wichtigste dieser Faktoren ist, und zwar
nicht nur diejenige des Bodens, sondern auch die der Luft. Diese hängt von jener ab.

ALVAREZ 55

In Mittelspanien sind zwei wichtige Regenperioden: im Frühling und im Herbst, und
dazwischen eine lange Trockenheitsetappe, die 2 bis 3Monate dauert. Diese Trocken-
heit ist so gross, dass die Schnecken immer einen Sommerschlaf (Estivation) halten
mtissen. Diese Unterbrechung der Lebensaktivitát ist bei hygrophilen Arten nicht
möglich, daher kommen diese in der untersuchten Fauna nicht vor. Wenn doch einige
zu finden sind, treten sie nur spärlich am Ufer von Gewässern oder an ganz speziellen
Biotopen mit mikroklimatischer Feuchtigkeit auf.

Der zweite Faktor in dieser Hinsicht ist die Temperatur, und zwar diejenige des
Winters mit sehr vielen Frosttagen, sowie die hohen Temperaturen des Sommers;
beide wirken sich in bezug auf Feuchtigkeitsmengen sehr ungünstig auf die Mollusken
aus. Es sind aber die grossen Schwankungen des typischen Kontinentalklimas Mittel-
spaniens, die eine wirklich negative Wirkung auf die Schneckenwelt haben. Man kann
daher nur wenige thermophile Arten finden.

DER MENSCHLICHE EINFLUSS AUF DIE VERBREITUNG DER SCHNECKEN

Dieser Einfluss wird im Laufe der Zeit leider immer grösser, vor allem bei den
Süsswasserarten. Es handelt sich aber nicht nur um die Bekämpfung von Zwischen-
wirten gefährlicher Viehschmarotzer, sondern im allgemeinen um alle Arten, die im
Wasser oder auf dem Land leben. Unter dem “menschlichen Einfluss” meine ich vor
allem das ständige und immer schnellere Wachsen der Städte, die so alle guten Orte
mit den interessanten Arten der Lokalfauna ganz zerstören und verschwinden lassen.
In der Umgebung der Stadt Madrid sind vielegrosse Teiche, bewaldete Orte mit Bächen
usw. ganz verschwunden, denen vor 60 Jahren viele Arten noch sehr häufig waren,
die jetzt ausserordentlich selten oder nicht mehr zu finden sind. In den Sammlungen
des National Museums in Madrid werdendieSchalendieser Arten aufbewahrt. Grossen
negativen Einfluss haben auch alle Abfallstoffe der Stadt und der Industrie, sowie die
Insektenvertilgungsmittel, die in die Gewässer gelangen. Viele kleine Nebenbäche des
Manzanares, die vor 30 Jahren dicht mit Planorbarius metidjensis (Forb.) besetzt
waren, beherbergen zur Zeit kein einziges Exemplar mehr,

Der menschliche Einfluss ist aber nicht immer negativ. Bei manchen Arten ist er
sogar so günstig, dass in einigen Jahren nur diese übrig bleiben werden, und zwar
immer in der Nachbarschaft des Menschen. Das ist der Fall z.B. mit H. (Cryptom-
phalus) aspersa Müll., obwohl sie, als Leckerbissen geschätzt, wie auch andere Arten,
in grossen Mengen verzehrt wird.

Die in Mittelspanien noch lebenden Arten.

1. Oxychilus lucidus Drap. 13. Jaminia quadridens (Müll.)

2. Euparypha pisana (Müll.) 14. Vallonia costata (Múll.)

3. Н. (Cryptomphalus) aspersa Müll. 15. Granopupa granum (Drap.)

4. Eobania vermiculata (Müll.) 16. Truncatellina rivieriana Bens.
5. Cepaea nemoralis (L.) 17. Succinea stagnalis Gass.

6. Leucochroa (Xeromagna) arigoi ROSS. 18. Radix auricularia (L.)

7. Н. (Xerotricha) conspurcata 19. Radix pereger (Müll.)

Drap. 20. Galba truncatula (Mull.)

8. Cernuella virgata da Costa 21. Physa acuta Drap.

9. Iphigena ventricosa (Drap.) 22. Planorbarius metidjensis Forb.
10. Cochlicella conoidea Drap. 23. Anisus spirorbis (L.)
11. Monacha cartusiana (Müll.) 24. Ancylus costulatus (Küst.)

12. Rumina decollata (L.) 25. Ancylus fluviatilis Müll.

56 PROC. THIRD EUROP. МАГАС. CONGR.

Arten, die während der letzten 40 Jahren verschwunden sind.

Arten Fundorte

1. Oxychylus pazi Bgt. Toledo

2. Ena obscura (Mull.) Escorial (Castafiar) VI-1917

3. Pupa gratiosa West. S. Fernando (Jarama) УП-1897

4. Lauria cylindracea Da Costa Escorial (Herreria) V-1920

5. Armiger crista (L.) Soto de Migascalientes (Madrid)

6. Hippeutis complanatus (L.) Soto de Migascalientes (Madrid)

7. Anisus perezi Gräells. Soto de Migascalientes, Rio Manzanares
und Casa de Campo (Madrid) VII-98.

8. Gyraulus albus limophilus (West.) Lozoya (Madrid)

9. Gyraulus albus (Müll.) El Pardo, Estanque d.l. Florida und

Escorial (Batán) (Madrid) V-1910.
SCHRIFTTUM

AHO, J., 1966, Ecological basis of the distribution of the littoral freshwater moll.
Ann. Zool. Fen. 3, p 287-322 Helsinski.

FROMMING, E., 1954, Biologie der mitteleuropiischen Landgastropoden, Berlin.

FROMMING, 1956, Biologie der mitteleuropiischen Süsswasserschnecken, Berlin,
(Dunk. Humb.)

GERMAIN, L., 1930, Mollusques terrestres et fluviatiles, FAUNE de FRANCE 21-22,
Paris, Lechevalier.

HAAS, F., 1929, Fauna malacológica terrestre у de agua dulce de Cataluña. Trab.
Mus. Cien. Nat. 13, Barcelona.

HUBENDICK, B., 1951, Recent Lymnaeidae, Kungl. Sv. Vetensk. Hand. 3, Stockholm.

JANUS, H., 1962, Unsere Schnecken und Muscheln. Kosmos, Stuttgart.

OKLAND, J., 1964, The eutrophic lake Borrevann (Norway) - an ecological... Folia
Lim. Scandinavica 13, Oslo.

MANIGAULT, Р., 1960, La coquille des Mollusques: structure et formation. in GRASSE
Traité de Zool. 51.2, Paris.

NEUMANN, D., 1961, Ernáhrungsbiologie einer rhipidoglossen Kiemenschnecke.
Hidrobiologia, Acta Hyd. Hydrograph. et Prot. 17, 1-2, Den Haag.

ABSTRACT

In this paper, the author points out the importance of the different soils and
tneir contents on chalk carbonate in the distribution of the pulmonata snails in
the center of Spain. He gives a description of each soil, its composition and its
geological origin in the surroundings of Madrid. It is given also an indication on
the preference of determinated soils or respectly waters for the 25 species
found in the studied country. He points out the most important climate factors,
such as temperature and wetness or dryness, and their influence on the snails.
At last he studied also the influence of men on the regression of the dispersion
of some species.

ALVAREZ 97

Landschnecken Arten

AO. lucidus Drap.

À Eup. pisana Mull.

№ Eob.vermiculata Müll.
ЖСер. nemoralis L.
DH.(Cript.) азрегза Müll.
BH.(Xerom.)arigoi Ross.

OH. (Xerct.) conspurcata Drap.
@H. (Cer) variabilis Drap.
+Coch. ventricosa Drap.

XCoch, conoidea Drap.
# Th. carthusiana Moll.
XR.decollata L.

\ у
, at ®Ch. quadridens Müll

р =
> ane | == ®V. costata Müll.
ER

OCr.granum Drop.

OTr.rivieriana Bens.

OS. stagnalis Gass.

Bodenarten Susswasserschnecken Arten

Q Ancylastrum fluviatile L.
OrPhysa acuta Drap.

O Coretus metitjensis Forb.

O Spiralina spirorbis L.
= SAND-KALK TONERDE GRANIT ее ое ми.

IM O Radix pereger (Mull)
SR [Ш ЕЕ ОВЕВОЕ Ф Radix auricularia L.

Die Verbreitung der Land- und Sússwasserschnecken in der Umgebung von Madrid in bezug
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MALACOLOGIA, 1969, 9(1): 59-64

PROC. THIRD EUROP. MALAC. CONGR.

CEPHALIC ACCESSORY SEXUAL ORGAN OF GYMNARION: SPECIATION
AND PHYLOGENY (PULMONATA, HELICARIONIDAE)

Eugéne Binder
Muséum d’Histoire Naturelle, Geneve, Switzerland

Several species of the African genus Gymnarion (PILSBRY, 1919) carry on their
head a peculiar organ (BINDER, 1964, 1965) that exists in no other genus and which
has been provisionally called the frontal organ. This organ is used in courtship,
when the snails remain for long periods head to head before copulating. Its complete
development is in correlation with that of the genital system, although there exists
no anatomical connection between both: it is complete only in adult individuals during
the mating season; accidental castration resulting in atrophy of the genital tract,
also leads to the atrophy of the frontal organ. This organ is situated above the snail’s
mouth, between the 4 tentacles and usually rather nearer the dorsal pair. It is re-
tractile and stays normally hidden inside the head while the animal is alive, but it can
be pushed out by the inner pressure of the body, in the same way as the tentacles.
This is possible because the organ is essentially a hollow expansion of the body-wall.
It is pulled back by retractor muscles which join dorsally the body wall’s muscular
layer. The surface is usually covered with numerous papillae, much smaller than the
warts on the rest of the body. In those species that were studied histologically, the
epithelium on this part is devoid of mucus cells. In some species there are lobes of
erectile tissue each carrying a calcified hook (BINDER, 1965).

Since the discovery of the frontal organ in a few species from the Ivory Coast and
Sierra Leone, I have had the opportunity to examine numerous specimens from various
parts of Africal, among which another 15 species possess a frontalorgan. These show
a remarkable diversity of shapes; most of them can be arranged in series in an attempt
to reconstruct their phylogenetical relationships.

The simplest form of frontal organ seen so far consists of a slight swelling of the
forehead (Mus. Tervuren, without origin). This could hardly be distinguished as a
frontal organ if it were not covered with many small papillae, which show it to be a
specialised area of the body surface (Fig. 1). Other simple forms appear as more pro-
nounced expansions, in the shape of a bag (Mus. Tervuren 218 271 - Elisabethville I),
and their surface has muchthe same appearance as that of the rest of the head (Fig. 2).
One species from Upemba National Park (IRSNB 2227) has a frontal organ in the shape
of a tongue, flattened and bent downward, covered with polygonal papillae separated
by deep furrows (Fig. 4). In one species of Nigeria (Tervuren 793 957) and one from
Chirinda Forest, South Africa, it has a conical shape and, in the latter species, it has
lost its warts and has a smooth surface (Fig. 3). Other variations derived from the
simple bag are the small narrow cylinder (IRSNB, Upemba 1882) (Fig. 5), or the strong

1 appreciation is expressed to the following for the loan of material for study: Dr. W. Adam,
Institut royal des Sciences naturelles de Belgique, Brussels; A. Houben, Institut des Parcs
nationaux, Brussels; Dr. P. L. G. Benoit, Musée royal de l’Afrique centrale, Tervuren; Prof.
E. Fischer, Museum national d’Histoire naturelle, Paris; Dr. R. Kilias, Naturhistorisches
Museum der Humboldt-Universität, Berlin; Dr. А. С. van Bruggen, Rijksmuseum van Natuur-
lijke Historie, Leiden; Dr. A. Holm, Zoologiska Institutionen, Universitet, Uppsala; Dr. R.
Oleröd, Naturhistoriska Riksmuseet, Stockholm.

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60 PROC. THIRD EUROP. MALAC. CONGR.

column found in Elisabethville I (Tervuren 794 831). In this species, the surface
of the frontal organ is without warts or papillae, but conspicuously wrinkled length-
wise. The end is flattened dorso-ventrally and divided in two rounded lobes which do
not carry hooks (Fig. 6).

Gymnarion with frontal organs carrying hooks seem to follow a separate line of
descent from the start. They were found up to now only in the western part of Africa,
from Sierra Leone to Angola. Those from the Loma Mountains (Sierra Leone) and
from Mount Nimba (Ivory Coast) have already beendescribed (BINDER, 1964). Several
species from Ghana (Tervuren 608 884) and Cameroons (Stockholm 425), seem to differ
only in the number of hooks, where the frontal organ is concerned. A species from
Angola (Berlin 39423) is very peculiar in that it has 12 to 15 pairs of hooks, each re-
tracting separately inthe middle of a circular pad (Fig. 7); the central pairs are largest
and the more lateral ones are smaller; on the edges of the frontal organ the pads
around the smallest pairs are scarcely bigger thanthe warts on the rest of the animal.
It looks as if there were a gradual change from face-wart to hook-and-pad. This
form seems to be rather primitive among the hooked frontal organs, being less dif-
ferenciated from the plain surface of the head. In the form from Misahóhe, Togo
(Berlin 47201), the 5 pairs of hooks can also be retracted individually, but the whole
frontal organ is encircled with a sphincter and a circular bulge, and is usually re-
tracted or pushed out as a whole (Fig. 8). This device is intermediate between the
former and the species of Mt. Nimba with their hooks arranged in a crown and en-
circled with a single sphincter. In those species, the number of hooks is somewhat
variable: each hook-carrying lobe can be split in two, or pairs of lobes can be re-
placed by single lobes. The passage from one formula to another with more or fewer
hooks is thus very easy. Only the knowledge of their distribution can give an indica-
tion as to which way the change has taken place; for instance, the 40-hooked G.
duplex”, which is very localised, is probably evolved from the more widely distributed
С. coronatus? with 12 hooks.

С. columna* from Mt. Loma shows a further step in evolution by raising its crown
of hooks on a strong cylindrical column (Fig. 9). С. апсйота?, also from Mt. Loma,
has the most elaborate form of frontal organ known so far, with its hooks reduced in
number to a single pair, but very large, inserted on the summit of a strong column
and with two tufts of finger-like papillae localised near the ventral edge (Fig. 10).
In these two last species, the lobes appear first during development, become retrac-
tible later, and the column develops last. The hooks are only differenciated from the
edge of the lobes when the animals are adults.

Some species are difficult to relate to anyother. For instance, one single specimen

2Description in the press. Called “forme B” in BINDER 1964.
314. , “forme A”.
“Description in the press. Called “forme C” in BINDER 1964.

Sid. , “forme D”.

ABBREVIATIONS TO FIGURES

dt, dorsal tentacle; fo, frontal organ; go, genital opening; h, hooks (broken in Fig. 8); m,
mouth; p, papillae; rh, retracted pairs of hooks; s, scale-like modified warts; vt, ventral
tentacle.

FIGS. 1-6.

Various shapes of frontal organ without hooks.

(See text. )

FIGS. 7-10.

PROC. THIRD EUROP. MALAC. CONGR.

Various shapes of frontal organ with hooks.

(See text. )

BINDER 63

FIG. 11. Frontal organ plus modified warts on the right side of the head. (See text.)

from Tshela, Congo (Tervuren 249 530) carries 3 straight horizontal strakes across
its front; it is uncertain whether these may at times differentiate hooks. This frontal
organ is supplemented by a curious differentiation of the body surface on the right
side, where the usual warts take on a rounded flattened shape and cover each other,
somewhat like scales (Fig. 11).

Summing up, there seem tobe two main trends: one toward a lengthening of a simple
expansion oí the body-wall and its modification into various shapes, the other toward
the development of hooks and their arrangement into diverse patterns, with eventually
the secondary formation of a carrying column.

As to the geographical aspect of this evolution, among the species known to this day,
those without hooks on their frontal organ are those from Central and South-East
Africa: Katanga, Zambia, S. Rhodesia, Tanganyika. The hooked species have all been
found on the Western side of Africa: Sierra Leone, Guinea, Ivory Coast, Ghana, Togo,
Nigeria, Cameroon, Lower Congo, Angola. Among these, the primitive forms occur
in Angola and the most evolved ones in Sierra Leone. If Vavilov’s principle applies
here, it would indicate that the frontal organ-carrying group of Gymnarion originated
in extreme West Africa.

The shape of the frontal organ, when present, is a very good taxonomical charac-
ter, and the first reliable one. The genus Gymnarion is remarkably uniform; until
now “species” were based on very unconvincing distinctions between shell forms, sizes
and proportions. Identifications, even by the best malacologists, were completely
random. Now it appears that there are many more species than it was ever suspected,
each clearly distinct from the others. These species are restricted to the rather par-
ticular habitat of altitude savannas or low, sparse mountain forest: they seem to need
a certain amount of light, but also of humidity, and they feed on dicotyledonous plants,
not on grass. This sort of habitat is broken up into many separate areas rising like
islands out of the almost continuous dense lowland forest of tropical Africa, and each
mountain range has its own species - or group of species - of Gymnarion with a
frontal organ. Thus there is at least a geographic cause to the subdivision of that
group into many species.

64 PROC. THIRD EUROP. MALAC. CONGR.

Being a means of recognition during courtship, and capable of a certain amount of
variability, the frontal organ might be in itself a factor of speciation, differences that
arise in this respect between populations acting as reproductive barriers. One would
be tempted to accept this as an explanation of the great number of species with frontal
organs, if it could be proved that the other species of Gymnarion are less numerous.
To investigate this, I have searched for other taxonomically useful characters in
species already clearly distinguishable by their frontal organ. I have found that the
details of the folds of the coating ofthe penis, which at first sight look rather acciden-
tal, differ in fact between species and show a perfect coincidence with the frontal
organ. The use of this new anatomical character, and perhaps others still to be dis-
covered, now makes a proper revision of the genus Gymnarion possible. The work
done until now has shown me already that there are also quite a number of species,
heretofore undistinguishable, among the Gymnarion without a frontal organ, and that
consequently a considerable amount of speciation has taken place in the absence of
that organ.

To ascertain the possible role of the frontal organ in speciation, it would be neces-
sary to study in the field the relations between recent or incipient species, where
they occur, like С. coronatus and G. duplex on Mt. Nimba. Failing this, it is not
possible to come to a conclusion on this point yet. The remarkable diversification
of shape of the frontal organ does not correspond to any adaptation to diverse environ-
ments or modes of life. Rather, like many features used at mating-time, it tends to
assume an exaggerated size and degree of elaborateness. This is perhaps because,
before being a means of species-recognition, such features are primarily a means of
recognition between individuals who are in the proper physiological state for repro-
duction, and extreme types can be favoured by selection if they elicit an overoptimal
mating response in other individuals.

Ethological observations are needed to reveal the exact functioning of the frontal
organ during courtship. Its existence implies a very particular mating behavior,
probably as diverse in detail among species as the organ itself; until now, it is only
known that, in С. coronatus, the partners approach each other from the front with their
organs retracted, press tightly front against front and remain a long time in that
position without moving; their frontal organ cannot be seen from the outside during
that phase.

REFERENCES

BINDER, E., 1964, Existence d’un organe de fixation sur la téte de certains Heli-
carionidae (Mollusques Gastéropodes). Arch. Sci., Genéve, 18: 89-92.

BINDER, E., 1965, Structure de l’organe sexuel frontal des Gymnarion des Monts
Nimba. Rev. suisse Zool. 72: 584-593.

SUMMARY

Many species of the genus Gymnarion Pilsbry exhibit between their tentacles a
retractile organ which exists in no other group of Molluscs. It plays a role in court-
ship and its development is in correlation with that of the sexual organs, it is thus an
external indicator of а Mollusc's endocrinological state.

This organ is distinctly different from species to species and provides a very good
taxonomic character. A tentative phylogeny of the known forms shows two main trends
in its evolution, but the causality of that evolution is not clear; it is not adaptive.

As a means of recognition between individuals of a same group, the presence of the
frontal organ may have an incidence on the mode of speciation by facilitating the
establishment of reproductive isolation between populations.

MALACOLOGIA, 1969, 9(1): 65-72
PROC. THIRD EUROP. MALAC. CONGR.

ETUDE DE LA CINETIQUE ET DE LAREPARTITION DU RADIOCESIUM
CHEZ UN BIVALVE D’EAU DOUCE (UNIO REQUIENI MICHAUD)

Р. Bovard, L. Foulquier et A. Grauby
CEN - Cadarache, France
INTRODUCTION

Les besoins croissants en énergie conduisent a un développement rapide des cen-
trales nucléaires. Cette industrie naissante pose un nouveau probléme hydrobiolo-
gique puisqu’elle contribue a augmenter la teneur de certains éléments dans le milieu
ou méme a en introduire d'autres. Га radioécologie doit contribuer á sa solution;
PEREDELSKY en donne la définition suivante: “La signification particuliére de la
radioécologie réside dans la possibilité de bien comprendre les chemins de la trans-
mission des radioisotopes, leurs concentrations et leurs dispersions... ainsi que
l’augmentation du danger pour l’homme due à la chaîne écologique des organismes
du milieu ou de la culture” [1]. Sur des bases écologiques et physiologiques un prob-
lème de radioprotection est posé [2], “c’est ainsi que telle algue ou tel mollusque
quoique n’ayant qu’une place insignifiante dans la chaîne alimentaire pourra être
choisi comme terme sensible à cause de son caractère révélateur de l’état de la
pollution.” [3] En eau douce, vu la variabilité des milieux, les études partent tou-
jours d’une situation locale.

Dans cette optique nous nous proposons d’étudier la cinétique du radiocesium chez
Unio vequieni (Michaud). Les échantillons ont été récoltés dans la partie Nord du
delta du Rhône où ils sont assez répandus. Le 137-cesium est un produit de fission
à vie longue que l’on retrouve dans les “retombées” à la suite des explosions nu-
cléaires ou dans les effluents issus du traitement du combustible irradié produits
dans les réacteurs nucléaires [4].

CONDITIONS EXPERIMENTALES

Les bivalves, par leur biogéographie, leur mode de vie et leur métabolisme con-
stituent des témoins biologiques intéressants. [5] [6] [7] [8] [9] Unio requieni a porté
successivement des noms différents; de nombreuses variétés ont été décrites.
GERMAIN ne signale qu’Unio requieni (Michaud) [10], il en donne une équivalence
avec Unio pictorum (Draparnaud, 1805). MARAZANOFF cite Unio requieni (Michaud)
[11] PERRIER [12], ADAM [13], ELLIS [14] n’indiquent que Unio pictorum (Linnaeus,
1758). Unio requieni (Michaud) est répandue dans toute la France, dans les riviéres,
les canaux et les étangs, en particulier dans l’Ouest et dans le Bassin Rhodanien.
Récemment, elle a été citée en Camargue par MARAZANOFF [11] [15]. Depuis, dans
cette région, nous l’avons retrouvée en d’assez nombreux endroits.

La distinction chez les bivalves entre la coquille et les “parties molles” a un
intérét pratique immédiat. La coquille, 4 métabolisme lent, pourra en quelque sorte
représenter l’historique de la radiocontamination; (par exemple pour le radiostrontium
suivant le métabolisme du calcium [6]). Les parties molles dont le métabolisme est
beaucoup plus rapide répondront de maniére directe aux fluctuations de la radio-
activité du milieu, (en particulier pour le radiocesium et le radiocerium). Mais leur
principale caractéristique réside dans leur grande capacité de filtration de l’eau.
Grace a l’action des cils vibratils l’eau rentre par le siphon inhalent, est filtrée a

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66 PROC. THIRD EUROP. MALAC. CONGR.

travers le réseau branchial et ressort par le siphon exhalent. Le transit de cette eau
permet une absorption directe des sels par diffusion a travers les membranes et une
incorporation par l’intermediaire de la nourriture [16] [17]. (La question restant
ouverte d’ailleurs quant А la qualité exacte de cette nourriture et au mode actif ou
passif d’alimentation.. .).

Les Unio, et ceci est important pour notre propos, sont donc en contact permanent
avec les deux éléments du milieu les plus susceptibles d’être contaminés; à savoir:
l’eau et les particules organiques ou minérales en suspension. Les bivalves ont tou-
jours été récoltés dans des zones dont le courant est faible ou nul. Les eaux sont
calcaires, dures, a pH légérement basique. Le sédiment est de type vaseux riche en
argiles.

Les animaux de tailles comparables sont placés au laboratoire dans des aquariums еп
résine polyester contenant environ 20 litres d’eau et 7 Kg de sédiment. On place une
quarantaine d’échantillons par aquarium. (Graphiques 1 et 2). On contamine l’eau
de l’aquarium en une seule fois en assurant la meilleure homogénéisation possible.
(Zu Ci/litre de 137-cesium). La solution utilisée est composée de 11y g/g de CO3 Cs»
a 26,9u Ci/g + 3% de 137-cesium.

L'eau est prélevée par pipettage dans des capsules et comptée aprés évaporation.
(Chaque point représente la moyenne de cing prélévements). Les animaux sont dis-
séqués; (trois lors de chaque prélevement); les organes sont pesés frais, placés a
l’étuve pendant 30 heures à 110°C et pesés secs (les parties molles sont placées telles
quelles dans les capsules de comptage; les coquilles sont broyées). On effectue les
comptages sur un sélecteur d’amplitude monocanal dont la sonde est constituée d’un
scintibloc SC3 №01 “3/4 2.” On suit pendant 70 jours l’évolution de la contamination
de l’animal; a ce stade on replace les bivalves dans de l’eau inactive et l’on étudie
pendant 230 jours le processus de décontamination.

RESULTATS

Etude de la contamination par le 137-cesium

a) Evolution de l’activité de l’eau et du sédiment

On observe une décroissance très rapide et tres importante de l’activité de l’eau.
On obtient, entre 15 et 20 jours, un “état d’équilibre” où l’activité de l’eau ne représente
plus que 0,5% a 1% de l’activité initiale. (Courbes 1) La majeure partie du radio-
cesium est passée dans le sédiment (98% environ). En effet il se produit une adsorption
et une absorption du radiocesium entre les feuillets alumino-silicatés des argiles.
Des liaisons rigides s'établissent qui provoquent une fixation irréversible du 137-
cesium. Ce phénomène constitue une loi générale de la migration du 137-cesium dans
les cours d’eau à fonds sablo-limoneux et vaseux [18]. En conséquence, dans des con-
ditions particulierement avantageuses du point de vue de la biomasse, les Unio ne
retiennent au maximum qu’1% de l’activité introduite dans l’aquarium. Ce 1% repré-
sente en quelque sorte une limite maximum de contamination puisque nos conditions
expérimentales correspondent a des conditions particulierement défavorables et qui
ne peuvent pratiquement pas se présenter dans la nature.

b) Evolution de l’activité des animaux

Nous considérons en premier lieu l’animal pris dans son ensemble en séparant
seulement la coquille, les parties molles et lesliquides internes. Les Courbes 1 per-
mettent de tirer un ensemble de données générales. A début de l’expérience les
animaux vivent dans une eau dont l’activite est élevée; pendant cette période d'une
dizaine de jours ils fixent une quantité relativement importante de 137-cesium. Il se

BOVARD, FOULQUIER and GRAUBY 67

produit corrélativement un processus de décontamination qui aboutit à un “état
d'équilibre” vers le 30&me jour (pour des gastéropodes d’eau douce TIMOFEYEVA
RESOVSKAYA donne 3 semaines) [19]. Avec un décalage dans le temps que nous ten-
terons d’expliquer plus loin, l’évolution de l’activité des animaux suit en quelque sorte
l’évolution de l’activité de l’eau. La donnée principale réside dans la très grande
difference que l’on observe entre l’activite spécifique de la coquille et des parties
molles. La coquille ne retient le 137-cesium que par des phénoménes d’adsorption.
Le brossage et le lavage éliminent la majeure partie de la radioactivité due aux parti-
cules de vase ou aux microorganismes [20] [9]. Le bord externe de la coquille a
toujours l’activite spécifique la plus élevée.

TABLEAU 1

Activités spécifiques (Des/min/g sec)

Temps
(jours) Coquille totale | Bord externe
—+
17 1 700 35 000
30 450 25 900
48 670 11 900
69 320 3 600
il

Il subsiste cependant des liaisons rigides que l’on ne peut enlever. On est autorisé
a penser que la fixation du 137-Cs par la coquille des bivalves est essentiellement
fonction de la surface mise en contact avec l’eau. Les parties molles ont une activité
spécifique beaucoup plus élevée (Ce résultat est assez général et se retrouve pour
d’autres radioéléments et d’autres espéces) [21]. Ici en effet ce sont de véritables
phénoménes métaboliques qui interviennent. Il peut se produire soit des échanges
ioniques directs entre l’eau et l’animal, soit une incorporation du radiocesium par la
nourriture. En ce qui nous concerne l’aquarium était place a l’obscurité dans une eau
contenant peu de microorganismes. Ce probléme a été abordé [8], mais des études
plus poussées devraient permettre d’établir quelle est l’importance respective de
chacun de ces processus physiologiques.

L’activité des liquides internes est trés faible mais cependant toujours supérieure
a celle de l’eau. Le liquide palléal est en “équilibre” avec l’eau; се sont donc sur-
tout le liquide extra-palléal et le sang qui ont une activité supérieure a celle de l’eau.
Des études a ce sujet sont en cours et démontrent essentiellement la rapidité des
échanges.

Si l’on considère la répartition de l’activité on constate que les parties molles
représentent 69% de l’activité de l’animal total (Graphique 2). Les chiffres sont com-
parables à ceux que nous avions obtenus sur Margaritana margaritifera (Linnaeus)
[9] GETSOVA, et al. sur Anodonta cellensis retrouvent 40% du 137-Cs dans la coquille
et le reste dans les parties molles (22). Pour aller plus loin dans l’analyse il faut
considérer uniquement l’activité des organes internes (Tableau 2). On peut constater
que, à l’“equilibre,” les écarts entre les activités spécifiques des différents organes
sont peu importants. C'est la masse musculaire qui présente les valeurs les plus
élevées (en particulier les muscles adducteurs). Il y a là une relation certaine avec
le fait que le muscle contient le plus fort pourcentage de potassium stable; vu sa
parenté chimique avec le cesium on peut considérer que ce dernier suit le métabo-
lisme du potassium. Cette relation a déjà été trouvée plusieurs fois et démontrée,

68 PROC. THIRD EUROP. MALAC. CONGR.

en particulier par les travaux de BRYAN [23].

Le manteau vient ensuite. Son bord a toujours une activité nettement supérieure
a celle de la partie interne (c’est peut-être en rapport direct avec l’activité élevée du
pourtour de la coquille). L'activité spécifique des siphons est peut-être due en partie
a de fines particules retenues par les cils vibratiles. La masse viscérale et les
branchies ont des activités spécifiques comparables (la valeur atteinte par les
branchies internes est toujours supérieure А celle des branchies externes). Tout
ceci joue plutót en faveur de mécanismes d’échanges directs du radiocesium.

Si l’on ne prend en compte que l’ensemble des parties molles, on constate qu'il
existe une “constante de distribution” du 137-cesium; les moyennes obtenues sont
exprimées dans le Graphique 4. Ces moyennes sont comparables a celles obtenues
par GETSOVA su Anodonta cellensis [22].

De ces données expérimentales nous pouvons tenter de dégager un certain nombre
de lois générales:

L’intensite des échanges du radiocesium est maximum entre l’eau et le sédi-
ment. L'activité de l’eau baisse tres rapidement au profit de la pellicule supér-
ieure de la vase. La quantité de radioélément retenue par les bivalves est faible
par rapport a l’activite introduite.

La coquille ne retient du 137-cesium que par des phénoménes d’adsorption;
pour les parties molles, au contraire, il s'agit de processus métaboliques.

L'activité spécifique des parties molles est toujours nettement supérieure a
celle de la coquille. Les activités spécifiques des différents organes sont com-

parables avec cependant des valeurs plus élevées pour les muscles!.

Cette capacité de fixation est fonction du métabolisme et des échanges osmo-
tiques qui s’établissent entre l’eau extérieure et l’animal. Ces échanges s’effec-
tuent en particulier entre les ions Cs* et Kt. A l’appui de cette thèse on peut
faire remarquer que la capacité de fixation du 137-Cs est beaucoup plus faible
pour les organismes marins que dulcicoles [23] [21].

Les differences en sels de l’eau influent sur la rapidité des échanges ioniques.
C’est pourquoi nous avions voulu étudier la dynamique de la décontamination
lorsque des “Unio” contenant une quantité connue de radiocesium sont replacées
dans un courant d’eau inactive.

Etude de la décontamination

La Courbe 2 montre que les parties molles sont essentiellement responsables du
mécanisme régulier de la décontamination. La coquille, malgré un processus de
décontamination visible, donne des résultats relativement anarchiques. П s’agit bien
d’un phénomène physique; les coquilles selon les circonstances, (degré d’enfouisse-
ment par exemple) ont adsorbé du radiocesium de manière plus ou moins intense.
L’activité des liquides internes n’est pratiquement plus détectable. Si l’on représente

Len radioprotection on exprime cette capacité de fixer les radioéléments par le “facteur de con-
centration. ” Il se définit comme étant le rapport, à l’“équilibre, ” entre l’activité spécifique de
l’animal (ou de l’organe) et l’activité spécifique de l’eau exprimée avec la même unité. Nous
avons obtenu les résultats suivants:

Animal total FC = 43 Masse musculaire FC = 347
Parties molles FC = 312 Masse viscérale FC = 308
Coquille FC = 10 Manteau FC = 314

Liquides internes FC = 3 Branchies FC = 308

BOVARD, FOULQUIER and GRAUBY 69

TABLEAU 2

Organes = TT
17 jours 30 jours
Es, = IL A Lee
Masse musculaire 21 800 19 300
Muscle du pied 19 600 18 400
Muscles adducteurs 23 400 20 000
Manteau total 23 600 17 700
Bord du manteau 24 600 18 500
Reste du manteau 18 000 16 200
Siphons 33 300 18 500
Masse viscérale totale 28 200 14 900
Branchies totales 30 600 14 800
Branchies internes 31 800 17 700
Branchies externes 29 900 13 100
Palpes 22 300 | 13 300
TABLEAU 3
Moyenne activité spécifiq. (Des/min/g sec)
u A. TES
aus ar u san 130 | al 180 | 230
mination |, J°UTS jours jours jours jours jours
Masse musculaire totale | 16 000 13 500 5900 4800 3900 3800 2800
Muscle du pied 15 200 11 600 4600 2600 2900 3700 2400
Muscles adducteurs 17 400 15 000 7200 7400 5100 3900 3500
Masse viscérale totale 17 000 10 900 4900 4300 3700 2600 2000
Branchies totales 17 000 10 700 4300 2700 2300 2300 1600
Branchies internes 17 900 11 500 | 2100 2900 2900 1700 1200
Branchies externes 16 200 10 000 6300 1900 2600
Manteau total 15 100 10 900 6200 4900 4400
Bord du manteau 16 700 11 700 5900 6600 5500
Reste du manteau 13 400 10 100 6400 | 4200 3600
Siphons 15 000 11 300 5000 5400 3000
5 300 3000 - 4100

Palpes 25 000

70 PROC. THIRD EUROP. MALAC. CONGR.

CONTAMINATION
( Evolution de l’activite spécifique)

Des/mn/g sec

Courbes №1

x parties molles
à д animal total
20.10 e coquille

Des/mn/g sec

Courbes N*2

x parties molles
4 animal total
* coquille

11 91 130 150 180 230 (jours)

(jours)

DECONTAMINATION

( Dynamique)

Des /mn/g sec Des/mn/g sec

1010? А 4 4 branchies
P 1010 x masse viscérale
+ masse musculaire

Courbes N2 3

Ty = 100)

01.10?

01:10?
230 (jours) n 91 130 150 180 230 (jours)

GRAPHIQUES de DISTRIBUTION de L'ACTIVITÉ

Repartition de Ll’activite

Pourcentage des poids

Pourcentage des pords Repartition de l'activite : :
41 - er | | 2 №4 Periode de
A Ge .
© / . DE contaminatıon
Au | AR ACC | |
№3 Poids frais moyen:
№1 Poids frars moyen: №2 Periode de 5,79 (parties molles )
229 (animal total) contamination
[I] Masse viscerale totale
> 1
EB coquitte Masse musculaire N°5 Après 230 jours
[=] Parties molles O Branchies de décont amination

E& Liquides internes E Manteau

BOVARD, FOULQUIER and GRAUBY 71

avec une échelle semi-logarithmique la décroissance de l’activité des parties molles
(Courbe 3) on constate qu’elle ne représente pas une fonction simple; une période de
décontamination rapide (T 1/2 = 8 jours) est suivie par une période de décontamina-
tion lente (Т 1/2 = 100 jours). (Ce type de courbe a déjà été trouvé sur des bivalves)
8] [20].
he Le de processus de décontamination se retrouve pour chaque organe (Tableau 3)
mais les vitesses diffèrent (Courbes 4). Ceci est bien visible pour les périodes
longues où l’on constate 30 jours d’écart entre les branchies et la masse musculaire.
Le muscle est bien l’organe préférentiel de stockage du 137-cesium. Par conséquent,
après 230 jours de décontamination, la masse musculaire représente, par rapport à
l’activité totale des parties molles, un pourcentage plus important (Graphique 5); il
en est de même pour le manteau. Par contre les valeurs de la masse viscérale et des
branchies ont baissé. Ces résultats ont surtout une importance pratique, puisqu'ils
permettent de définir le temps nécessaire pour qu’un animal (ou un organe) perde la
majeure partie du radioélément incorporé à la suite d’une radio-contamination aiguë.

CONCLUSION

Nous retiendrons quelques données essentielles: la quantité de radiocesium fixée
par les bivalves est faible par rapport а l’activite introduite. Le véritable métabo-
lisme du radioélément se situe au niveau des parties molles. Га capacité de fixation
du 137-Cs est différente pour chaque organe, le “facteur de concentration” est maxi-
mum pour ceux ayant une forte teneur en potassium stable, comme les muscles. Les
phénomènes de diffusion à travers les membranes et de transfert actif des sels sont
responsables de la majeure partie de l’absorption du 137-Cs. On rejoint ainsi les
travaux de FLORKIN sur l’osmorégulation [24]. Si l’on considère que l’ion Cs+ suit
les mêmes voies que l’ion K*, il est normal que dans un milieu où la quantité de potas-
sium est faible la dose de cesium fixé soit proprtionnellement forte. Le même
raisonnement s’applique a la décontamination puisque les bivalves rejettent une urine
hypoosmotique. La période biologique est donc relativement longue. Ces données,
d’ordres écologique et biologique, définissent sur le plan de la protection les con-
ditions locales les plus favorables a une contamination des “Unio” par le 137-Cs. Ces
conditions sont remplies dans des zones peu éloignées du point de rejet, a fonds sablo-
vaseux, peu profondes et а courant lent. Dans de tels sites l’utilisation de ces bivalves
comme “dosimétres biologiques” dans le cas d’une pollution par le 137-césium parait
valable. Ce type d’étude qui nécessite de nombreux approfondissements permet
cependant de mettre en relief la nécessité de lier les problémes appliqués a ceux de
la recherche fondamentale.

BIBLIOGRAPHIE

[1] PEREDELSKY, А. A., 1957, Fondements et problèmes de la radioécologie. Zh.
Obshch. biol. SSSR., 18-1: 17-30.

et problemes pharmaceutiques, 20(2): 3-8.

] BOVARD, P., 1966, La Radioécologie. В. 1. S. T., 106: 37-38.

] FONTAINE, Y., 1960, La contamination radioactive des milieux et des organ-
ismes aquatiques. Rapport C. E. A., 1588 (France): 15-37.

] CARTER MELVIN, W., 1961 Biological uptake of radioactive nuclides by clams.
University of Florida LC. Card. No. Mic. 60-6662.

6] NELSON, D. J., 1962, Clams as indicators of strontium-90. Science, 137(3523):
38-39.

72 PROC. THIRD EUROP. MALAC. CONGR.

[7] RAVERA O., ET AL., 1962, A research program for the study of radioactivity in
mollusks as a possible index to the contamination of a lake. N.S. A., 16(17):
22428.

[8] CANCIO, D., FOULQUIER, L. & GRAUBY, A., 1968, Modalitésde la contamination
d’un bivalve d’eau douce par le radiostrontium etde sa décontamination: Anodonta
cygnea (L.). Rapport C.E.A., R-3421. Documentation Frangaise, Paris, 34 p.

[9] FOULQUIER, L., BOVARD, P. € GRAUBY, A.,1966, Contamination expérimentale
de Margaritana margaritifera (L.) par le 137-cesium. Rapport C.E.A., R-3054.
Documentation Francaise, Paris, 34 p.

[10] GERMAIN, L., 1931, /n: Faune de France. XII-T 1, Mollusques. Ed., Lechevalier,
Paris, p 715-774.

[11] MARAZANOFF, F., 1964, Introduction a l’étude écologique des mollusques des
eaux douces et saumâtres de Camargue. La Terre et la Vie, 3: 359-374.

[12] PERRIER, R., 1930, In: Faune de la France illustrée. T IX Mollusques. Ed.,
Delagrave Paris, p 118-119.

[13] ADAM, W., 1960, In: Mollusques terrestres et dulcicoles. Т.1. Inst. Roy. Sci.
natur. Belg., Bruxelles, p 325-330.

[14] ELLIS, A. E., 1962, In: British freshwater bivalve molluscs. Ed., Burlington
House, Piccadilly, London, p 10-16.

[15] MARAZANOFF, F., 1964, Complément a l'inventaire de la faune invertébrée
camarguaise. La Terre et la Vie, 3: 375-379.

[16] ROBERTSON, J. D., 1964, Osmotic and ionic regulation. In: Physiology of
Mollusca. Т.1. Eds., К. М. Wilbur & С. М. Yonge, Acad. Press, New York and
London, p 283-331.

[17] OWEN, G., 1966, Feeding. In: Physiology of mollusca. TI. Eds., K. M. Wilbur
& C. M. Yonge., Acad. Press, New York and London, p 29-42.

[18] CLANTON, H., 1963, Sorption and release of radionuclides by sediments. T.I.D.,
17664: 113-125.

[19] TIMOFEYEVA-RESOVSKAYA, Ye. A., 1963, Distribution of radioisotopes in the
main components of freshwater bodies. (Monograph.) (J.P.R.S. 21-816). Tr.
inst. Biol. Akad. Nauk. SSSR., Ural’skiy filial (30): 1-78.

[20] LEANDRI, M. & CHARREL, J., 1963, Essais de décontamination expérimentale
des coquillages méditerranéens pollués par des eaux rendues radioactives. Rev.
Hyg. et Méd. Soc. T. 2(5): 411-416.

[21] POLIKARPOV, G. G. 1966, Concentration of radionuclides of the first group of
elements in the periodic system. In: Radioecology of aquatic organisms. North-
Holland Publ. Co., Amsterdam; Reinhold Book Div., New York, p 61-80.

[22] GETSOVA, A. B., LYAPUNOVA, N. A., POLIKARPOV, G. G. & TIMOFEYEVA-
RESOVSKAYA, Ye. A., 1964, Concentration of chemical elements from aqueous
solutions by freshwater organisms. Commun. 6. Accumulation of the radioiso-
topes of eight different elements in the tissues of Anodonta cellensis. Nauchn.
Dokl. Vyssh. Shkoly (Biol.), 4: 82-88.

[23] BRYAN, G. W., 1963, The accumulation of cesium-137 by brackish water inverte-
brates and its relation to the regulation of potassium and sodium. J. Mar. biol.
Ass. U. K., 43(2): 541-565.

[24] FLORKIN, М. € DUCHATEAU, G., 1948, Sur l’osmorégulation de 1'Anodonta
cygnea. Physiol. Comp. et Oecol., 1:29-45.

MALACOLOGIA, 1969, 9(1): 73-78

PROC. THIRD EUROP. MALAC. CONGR.

TAXONOMIE ET BIOLOGIE DES GRANDS ARION DE FRANCE
(PULMONATA: ARIONIDAE)

H. Chevallier

Laboratoire de Malacologie,
Museum National d’Histoire Naturelle, Paris, France

1. Systématique

Trois grandes espéces du genre Arion ont été identifiées en France: Arion rufus
(L.) (=A. ater rufus Quick), Avion lusitanicus Mabille et Arion subfuscus Draparnaud.
On a l’habitude de classer Arion rufus dans le sous-genre Arion s.s. ( = Lochea) et
А. subfuscus dans le sous-genre Mesarion. L’espèce А. lusitanicus, encore peu
étudiée, appartient au groupe de А. rufus par ses caractères externes et généraux
mais son appareil génital se rapproche morphologiquement de celui des Mesarion
(Fic. №):

L'étude du polymorphisme de ces trois espéces et des étapes de leur croissance
permet de placer dans la synonymie probablement tous les autres grands Arion cités
en France par la littérature. En particulier Avion ater Germain, A. aggericola Mab.,
A. hibernus Mab., A. brevierei Poll., А. rubiginosus Baudon, A. flavus Nilss., A.
tenellus = virescens Millet se rapportent tres vraisemblablement a des variétés ou
à des formes juvéniles ou séniles de A. rufus, А. lusitanicus et A. subfuscus.

2. Répartition géographique

Arion lusitanicus est répandu en France principalement au sud de la Loire: Vendée,
Charente maritime, Gironde, vallée de la Garonne, Massif Central, Gard, Pyrénées
centrales et orientales. On le retrouve près de Paris et a Reims ou il a sans doute
été introduit (Fig. 2).

Arion rufus occupe le Nordetl’Estdela France, la région parisienne, la Normandie,
la Bretagne, la vallée de la Loire, la Dordogne et les Pyrénées occidentales.

Arion subfuscus parait répandu dans presque toute la France mais il semble manquer
dans les parties hautes des Pyrénées.

3. Variations et Taxonomie

Il existe une variation chromique de A. lusitanicus et A. rufus en relation avec
l’altitude. Nous avons constaté ce phénomène dans le Massif Central, pour A. lusi-
tanicus, et dans les Pyrénées, pour A. lusitanicus et A. rufus. A partir de 500 m
d’altitude, ces deux espéces présentent des variétés mélaniques parfois similaires:
formes noires ou brun foncé. Ces variétés sombres d’altitude de A. lusitanicus et
A. rufus correspondent, dans l’ensemble, а l’“Ayion ater” (non Arion ater ater Quick)
cite par la plupart des anciens auteurs francais comme “un grand Arion noir vivant
dans les montagnes.”

Plus précisément la variété noire de A. lusitanicus (var. nigrescens Collinge)
correspond à l’ Arion nobrei Pollonera. La variété noire de A. rufus (var. atra (L.)),
elle, offre dans les Pyrénées les variantes suivantes: la variété atra aterrima Dumont
et Mortillet est toute noire; la variété atra marginella (Schranck) présente la marge
du pied jaune ou orangée; enfin nous avons trouvé une forme atra sulcata Morelet

(73)

PROC. THIRD EUROP. MALAC. CONGR.

FIG. 1. Parties supérieures de l’appareil génital de grands Arionidae de France (x 3,5 à 5).
В. Arion lusitanicus Mab. , Livry-Gargan près de Paris.

A. Arion rufus(L.), Seine maritime.
С. Arion subfuscus Drap. , forêt de Compiègne.
dentales frangaises.

D,E,F. Arion rufus (L.) des Pyrénées occi-
О: exemplaire de Bidarray; E: ex. de Ferrieres, val de l’Ouzon, alt. 555

т (var. atra sulcata); Е: ex. du col d’Aubisque, alt. 1710 m (var. ата marginella).

ai
as
e
1
O

atrium inférieur
atrium supérieur
épiphallus

ligula

oviducte

od
ol

oviducte partie distale
oviducte libre
muscles rétracteurs
spermiducte

vésicule séminale

CHEVALLIER 75

FIG. 2. Répartition en France de Arion lusitanicus Mabille.

но J Е м A м Е J A 5
(1967)

mois (1968)

FIG. 3. Croissance pondérale de Avion lusitanicus, á Paris (Le trait épais correspond a la
croissance moyenne d’individus placés А température externe; le trait interrompu а celle d’in-
dividus, provenant de la méme éclosion, élevés 4 17-20°C. Les courbes en traits fins corres-
pondent 4 la croissance estivale et aux phases adultes et séniles de deux individus placés en-

semble 4 température externe).

76 PROC. THIRD EUROP. MALAC. CONGR.

correspondant bien à l’Arion sulcatus décrit et figuré par Morelet (1845, р. 28, pl. 1):
gros Arion assez amorphe, noir ou brun trés foncé, a tubercules vermiculés et trés
saillants et a marge du piedbrune oude la couleur du corps. L’appareil génital de ces
formes pyrénéennes ne nous a pas semblé offrir de différences trés nettes avec celui
des Arion rufus du Nord de la France (Fig. 1). Nous rangeons donc, pour le moment,
les Arion s.s. des Pyrénées occidentales francaises dans l’espéce Arion rufus (L.).

4. Cycle biologique et croissance

A. rufus, A. lusitanicus et A. subfuscus présentent un cycle normalement annuel:
croissance juvénile au printemps, stade adulte et reproduction en été, ponte le plus
souvent en octobre et mort du géniteur en général peu de temps aprés la ponte (phase
sénile). Ceci concorde avec les histogrammes en valeurs pondérales et en stades de
maturité génitale donnés par В. J. Smith (1966) pour une population naturelle d’Arion
ater (A. ater ater Quick) en Grande Bretagne et aux courbes de croissance établies
par Abeloos (1942, 1944) pour A. rufus et A. subfuscus placés en élevage a 20° C.

Abeloos distinguait trois phases de croissance: la phase infantile, la phase juvénile
et la phase adulte s’achevant par la sénilité. Ces trois phases correspondent aux
stades de gamétogenése découverts par Lüsis (1961) pour A. rufus et par В. J. Smith
(supr. cit.) pour A. ater: stade male, stade hermaphrodite et stade femelle.

Sur le plan biométrique la phase juvénile se décompose en deux périodes: une période
pré-estivale a taux de croissance modéré, variant principalement sous l’effet des con-
ditions climatiques (température), et une période de croissance estivale a taux trés
fort qui amène l’animal au stade adulte (Fig. 3).

5. Facteurs modifiant la croissance

Des expériences, inspirées par celles d’Abeloos, concernant la modification de la
vitesse de croissance sous l’effet de facteurs défavorables (jeüne ou sous-alimentation,
basse température, surpopulation) ont été effectuées. Ces expériences mettent en
évidence la plasticité de la croissance durant la phase infantile et la phase juvénile
pré-estivale. Par plasticité nous entendons un processus de croissance qui permet a
l’animal trés jeune d'atteindre la taille etle stade génital précédant la phase de crois-
sance estivale quels que soient les facteurs externes entrant en jeu durant la période
pré-estivale. Expérimentalement ceci signifie que des Arion infantiles ou très jeunes
soumis a un facteur défavorable voient leur taux de croissance devenir faible, nul ou
négatif pendant le temps où le facteur inhibiteur se fait sentir, mais que, dès que
celui-ci est supprimé, les jeunes Avion prennent untaux de croissance leur permettant
de retrouver les valeurs pondérales normales. L'expérience de la Fig. 3 montre,
ainsi, que des Avion nés en laboratoire en novembre et élevés a 17-20° C présentent
un taux de croissance juvénile pré-estivale constant. Des individus issus de la méme
éclosion et élevés a la température extérieure ont, eux, un taux de croissance faible
pendant les froids del’hiver mais le taux va augmenter au printemps, avec l’adoucisse-
ment de la température, si bien que ces individus ayant subi le froid atteindront le
méme stade pondéral et génital que leurs congénéres élevés a la température du
laboratoire.

L'expérience portant sur l’effet d’un jeûne durant la période pré-estivale conduit a
un résultat similaire: de très jeunes Arion soumis à un jeûne d’une vingtaine de jours
regagnent, au bout de quatre mois, la valeur pondérale pré-estivale des individus
témoins (loi d’Abeloos).

Par contre les facteurs défavorables altèrent, plus ou moins profondément, le terme
de la croissance s’ils surviennent au seuil de la croissance estivale ou durant celle-ci.

CHEVALLIER dd

Poids

13 - EN
*

11 ye 2 E
IN RES
a “e de
9 —
ASK Y N
/ ORY
7 OS ul
es A а
o
5 TES Ÿ
и ys
E BER e Individus
= Soumis au jeune
—* >
8 Aa x Témoins
he ae ais O yy Pontes

J J A $ O N D
mois(1968)

FIG. 4. Effet de dénutrition (jeúne de 21 jours) sur la croissance terminale de Arion lusi-
tanicus à la fin de la période pré-estivale (stade pondéral de 2 g). Elevages mis à température
externe, a Paris.

Prenons, par exemple, l’effet d'un jeûne sur des А. lusitanicus terminant leur crois-
sance juvénile pré-estivale (Fig. 4). Les individus ayant subi le jeúne parviendront
au stade adulte mais un peu plus tard que les individus témoins et avec des valeurs
pondérales plus faibles. Leurs pontes seront &galementtardives: celles des individus
témoins vont éclore, aprés une incubation de 30 jours, avant les froids; les oeufs des
individus retardés ne pourront éclore qu'apres l’hiver, c'est à dire vers le mois de
mars.

Si les facteurs défavorables surviennent durant la croissance estivale, celle-ci sera
le plus souvent stoppée. Au lieu d’être adulte, 1’Avion demeurera, en automne, à un
stade génital juvénile. Expérimentalement nous avons constaté que de tels individus a
croissance arrétée survivent avec une valeur pondérale et un stade génital station-
naires et qu’ils reprennent parfois leur croissance au printemps de l’année suivante.

6. Conséquences écologiques

Tous ces phénomènes expliquent la physionomie particulière à chaque station des
populations naturelles d’Arion: cycles écologiques différents, tailles adultes inégales,
etc. Les facteurs caractéristiques de chaque biotope (latitude, microclimat, végéta-
tion, éléments nutritifs, densité de la population, espèces concurrentes . . ) jouent un
rôle d’accélérateur ou de ralentisseur de la croissance de la population ou d’une partie
de la population. Les facteurs défavorables sont particulièrement inhibiteurs, nous
l’avons vu, au moment de la croissance estivale: ils retardent le stade adulte et, de
ce fait, les pontes, ils abaissent la taille et le poids des individus adultes et, dans
certains cas, ils peuvent arrêter totalement la croissance pondérale et génitale.

78 PROC. THIRD EUROP. MALAC. CONGR.

Le cycle écologique des grandes espéces du genre Avion est donc de un an dans
beaucoup de cas; mais les individus n’ayant pas atteint le stade adulte en automne, soit
parce que nés trop tardivement, soit parce qu’ayant eu leur croissance estivale per-
turbée, sont succeptibles de parvenir au stade adulte durant l’été de l’année suivante,
aprés avoir subi un repos de croissance de plusieurs mois.

LITTÉRATURE CITÉE

ABELOOS, M., 1942, Les étapes de la croissance chez la Limace rouge (Avion rufus
L.). Evolution des caractéristiques de croissance chez les Mollusques Arionidés,
С. В. Acad. Sc. Paris, 215: 38 et 96.

ABELOOS, M., 1944, Recherches expérimentales sur la croissance. La croissance
des Mollusques Arionidés, Bull. biol. France & Belg., 78: 215-256.

LUSIS, O., 1961, Postembryonic changes in the reproductive system of the slug Arion
ater rufus L., Proc. Zool. Soc. London, 137: 433-468.

MORELET, A., 1845, Description des Mollusques terrestres et fluviatiles du Portugal,
Paris.

SMITH, В. J., 1966, Maturation of the reproductive tract of Arion ater (Pulmonata:
Arionidae), Malacologia, 4(2): 325-349.

MALACOLOGIA, 1969, 9(1): 79-84
PROC. THIRD EUROP. MALAC. CONGR.
BIOLOGICAL ASPECTS OF MANGROVE MOLLUSKS IN THE WEST INDIES
Henry Е. Coomans
Zoological Museum, Amsterdam, The Netherlands
INTRODUCTION

Mangroves form a very special tropical shore habitat. Mangrove trees are found
in shallow salt or brackish water, with a mud or sand bottom. The water needs to be
calm, therefore lagoons, bays and estuaries are preferable. Most mangroves are
found between 25° (to 30°) north and south latitude. According to McGill (1958) man-
groves dominate about 75% of the tropical coastlines.

There are two mangrove floras in the world, an oriental or Indopacific (East Africa,
Indian Ocean and West Pacific), and an occidental mangrove flora (tropical America
and West Africa). Compared to the Indopacific, the occidental flora is very poor in
species of mangrove trees. According to Van Steenis (1962, р. 166) the Indopacific
has 43 species of mangroves, while in tropical America and West Africa only 10
species occur. However, other authors (Abel, 1926) recognize 23 species in the Indo-
pacific, and 4 mangrove species in America and West Africa. In the West Indies are
present: the red mangrove, Rhizophora mangle L. (fam. Rhizophoraceae); the black
mangrove, Avicennia nitida Jacq. (Verbenaceae); the white mangrove, Laguncularia
vacemosa Gártn. (Combretaceae); and the grey mangrove, Conocarpus erectus L.
(Combretaceae). Mangroves do not formone systematical unit, they belong to different
families of Dicotilous plants. They are unusualfor the fact that they are higher plants
living in seawater.

Every species has its special place in the mangrove wood: Rhizophora is growing
close to and in the water, Avicennia, Laguncularia and Conocarpus are usually found
farther inland. The four species do not always grow together, the community often
consists of only one or two species. Rhizophora mangle is mostly present.

To live in their special habitat, mangroves are furnished with aerial and prop roots.
The reproduction is peculiar because mangroves are viviparous: the seeds on the
tree are growing out into seedlings, and the seedlings can be transported via the sea
to new lands or islands far away. Therefore, mangroves are excellent pioneer plants
(Stephens, 1962).

Compared to the rich tropical flora, the mangrove habitat is very poor in number
of species. This is also true for the fauna: the number of species is small, however
the number of specimens is often very large. The distribution of animals in a man-
grove Swamp is more complex than the zonation of a rocky shore (Berry, 1963);
physical conditions vary in the mangrove area.

The mollusks of the West Indian mangroves are the subject of this study. The
author has studied mangrove mollusks on the Netherlands Antilles and in Puerto Rico,
and he has visited several mangrove areas in Florida.

MOLLUSKS OF THE CARIBBEAN MANGROVES

For the malacologist only the red mangrove, Rhizophora mangle, is important, as
shells have only been found on this tree in the West Indies. The prop roots of Rhizo-
phora are an excellent substratum for many animals to live on, not only mollusks,
and algae are also found on the roots. The relation of mollusk to mangrove is dif-
ferent for many species. We are, therefore, able to make a division.

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80 PROC. THIRD EUROP. MALAC. CONGR.
1. Exclusive mangrove mollusks

Only three species are always and only found on the prop roots: one gastropod,
the periwinkle Littorina angulifera (Lamarck), and two pelecypods, Crassostrea
rhizophorae (Guilding) and Isognomon alata (Gmelin).

Littorina angulifeva is very common and lives on the roots above the water. We
found 1 to 3 specimens at one branch, never crowded together. Sometimes the animal
climbs аз high as the leaves, but mostly it stays near the water. This peculiar marine
snail is more a land thanawater animal. Our experiments showed that when a number
of specimens were kept submerged in seawater, 50% of the animals died within two
days (Coomans, 1962). Littorina angulifera reacts on the water level; in areas with
tides or wave action, the animals are found higher on the roots than in areas without
tides or waves. This species is the first mollusk that appears on new mangroves,
as was found by us on newly formed mangrove islands in Puerto Rico. With its host
plant Rhizophora mangle, Littorina angulifera is found on both sides of the Atlantic
Ocean (Rosewater, 1963). This periwinkle was extensively studied by Lenderking
(1954) and Marcus & Marcus (1963).

Crassostrea rhizophorae, the mangrove oyster, is the second mollusk to be a true
mangrove species, found only on Rhizophora, after which it is named. The oyster
prefers the mangroves in lagoons, and is not often found in open sea, where it never
reaches the maximum size. The shell grows fast, 5 cm in half a year. The maximum
size is 10 cm. The oysters are crowded together on the prop roots, fixed with one
valve to the mangrove. This species is edible and commercially used, but the oysters
can only be collected with the substratum. These mollusks are responsible for the
story of the seamen from centuries ago that in the tropics the oysters grow on trees!
Mattox (1949) has studied Crassostrea rhizophorae in Puerto Rico.

The species is not found on the mangroves in Florida; the mangrove oyster there
is Crassostrea virginica (Gmelin). The distribution of C. virginica is from Florida
north to the Gulf of St. Lawrence.

Isognomon alata (Gmelin), the flat oyster, lives in clusters on the mangrove roots,
attached with a byssus. This species is more common in the Netherlands Antilles
than in Puerto Rico.

2. Sessil pelecypods often found on mangroves

Many bivalves are fixed to a substratum with one of the valves or with a byssus,
and these species can also be found on mangroves. Brachidontes exustus (Linné) is
common under water from top to bottom onthe prop roots. This small mussel also
lives on stones outside the mangrove lagoon. A larger mussel species, Br. recurvus
(Rafinesque), is also found on mangroves, but it is not so common. The third Carib-
bean species, Br. citrinus (Röding), is not recorded from mangroves. More Mytilidae
are mentioned in the literature to be found on the roots of Rhizophora: Modiolus
americanus (Leach) from Margarita Island (Rodriguez, 1959, p. 277), and Mytella
guyannensis (Lamarck) from Brazil (Gerlach, 1958, p. 668).

Both West Indian pearl oysters, Pteria colymbus (Röding) and Pinctada radiata
(Leach) can be found on mangroves; also several Chamidae are recorded, i.e., Chama
macerophylla Gmelin and С. congregata Conrad. Ostrea frons Linné, commonly
attached with one valve to sea fans (Gorgonaria), is occasionally found on mangroves.
The list can be closed with Anadara notabilis (Röding), Isognomon radiata (Anton), and
Pododesmus rudis (Broderip).

3. Predators of mangrove oysters

Since the prop roots of Rhizophora are often loaded with oysters, these animals are
attracting predating gastropods. The carnivorous Murex brevifrons Lamarck is a

COOMANS 81

common predator onthe oysters. Ontheislands Aruba and Bonaire we found Melongena
melongena (Linné) associated with mangrove areas; in Florida it is Melongena corona
(Gmelin). The South American Pugilina morio (Linné) is reported from mangroves
on Martinique (Usticke, 1960); this is probably the most northern distribution of the
species.

4. Sessil mollusks on mangrove oysters

A number of small gastropods use the shells of the mangrove oysters to live on,
although they are also found elsewhere. Other sessil animals are living, too, on the
oysters: Balanus spec. and tube worms. Several limpets were collected by us from
the mangrove oysters: Diodora cayenensis (Lamarck), Lucapina sowerbii (Sowerby),
Emarginula pumila (A. Adams), Hemitoma octoradiata (Gmelin), several Acmaea’s,
and the pulmonate Szphonaria. Two slipper shells, Crepidula aculeata (Gmelin) and
С. convexa Say are Rhizophora bound. On the very crowded roots the oysters are
growing one on another, and the mytilid Brachidontes exustus (Linné) often lives in
great quantities on the mangrove oysters.

5. Boring pelecypods in mangrove roots

The wood borer Teredo is found in either living or dead mangrove wood, and it is
surprising that the stone boring Lithophaga bisulcata (d’Orbigny) is mentioned from
mangroves in Curacao.

6. Mollusks living in or on other organisms at the mangrove roots

The prop roots of Rhizophora in the West Indies are often crowded with organisms.
In addition to oysters, one finds Crustacea (Balanus, hermit crabs, shrimps), Tunicata
(Ascidia nigra, Bothryllus), Bryozoa, Vermes, Echinodermata (brittle stars), Coelen-
terata, Porifera, and algae.

A number of mollusks are living in or onthese organisms: Ostrea permollis
Sowerby and the tube shell Vermicularia knorri (Deshayes) live in sponges. A small
mytilid, Musculus lateralis (Say) finds a host in Bothryllus, many mussels live to-
gether in the mantle of this tunicate.

Many species of green, red and brown algae are found on the prop roots, and they
serve as hosts for small gastropods. Robertson (1960) found seven species of gastro-
pods on the red alga Bostrychia in the Bahamas. Warmke & Almodovar (1963) men-
tioned some 80 tiny species of gastropods and12 pelecypods collected from 25 species
of algae in Puerto Rico. A number of these algae were found on mangroves.

The first Caribbean bivalved gastropod, Berthelinia caribbea Edmunds, was found
on the alga Caulerpa from mangrove beds at Jamaica (Edmunds, 1962, 1963). The
species was also collected on mangrove algae in Puerto Rico (Warmke, 1966).

7. Mollusks of the mud flats

Mangroves always are growing on sand or mudto hold the roots. In this substratum
burrowing pelecypods are living; they belong to the mangrove fauna, although they are
never found on the mangrove trees. Some of the bivalves often found burrowed in the
sandy or muddy bottom of the lagoon are Asaphis deflorata (Linné) and Trachycardium
muricatum (Linné), several Lucinidae, and the Veneridae Anomalocardia brasiliana
(Gmelin) and Chione cancellata (Linné).

Gastropods are crawling on the mud flats, and since they are able to move around
these gastropods are regularly found on the mangrove trees. Some of them are
present in very large numbers: Batillaria minima (Gmelin), Cerithidea costata
(Da Costa), Neritina virginea (Linné), Cerithium variabile С. В. Adams, Bulla species,
and some Ellobiidae: Melampus coffeus (Linné) and M. bidentatus Say, Detracia

82 PROC. THIRD EUROP. MALAC. CONGR.

bullaoides (Montagu) and Tralia ovula (Bruguiere) (cf. Morrison, 1958). Melampus
coffeus was studied by Golley (1960) and by Marcus & Marcus (1965, p. 20-42). Not
all the gastropod shells climbing on mangrove roots do contain mollusks, some of
them are inhabited by hermit crabs.

8. Gastropods of the mangrove lagoon

Mollusks from the mangrove lagoon, living on stones or other organisms, can
occasionally be found on the mangroves. To mention some of them: Cerithium lit-
teratum Born and C. eburneum Bruguiére, Columbella mercatoria (Linné), Fascio-
laria tulipa (Linné), Modulus modulus (Linné), Purpura patula(Linné). Edmunds (1964)
collected thirteen species of eolid nudibranches from mangrove roots in Jamaica.

Cypraea zebra Linné is living in Florida onmangroves; however, on the West Indian
islands this species does not belong to the mangrove fauna.

9. Mollusks from outside the mangrove area

Accidentally, some intertidal mollusks from the seashore may enter the mangrove
lagoon and try to reach their intertidal habitat by climbing the mangrove trees.
Several Neritidae and Littorinidae are thus living on the prop roots of Rhizophora
mangle. They maintain the zonation as in their natural habitat on the rocks: Nerita
tessellata Gmelin and Littorina nebulosa (Lamarck) are close to the water, Nerita
versicoloy Gmelin and N. peloronta Linné more upward, while Tectarius muricatus
(Linné), when found on Rhizophora, is far from the water.

When the mangroves are in open sea, close to the rocky shore, the intertidal gastro-
pods from the rocks are found more often on the prop roots.

DISCUSSION

Comparing the Caribbean mangrove mollusks with those from the Indopacific man-
groves (cf. Lim, 1963), it is striking that many of the mangrove mollusks in both
faunas belong to identical families, and often to the same genus, which is shown in
the list below. Since Lim’s study is not an inventarisation of the oriental mangrove
mollusks, the species mentioned from the West Indies are also selected.

West Indies East Indies
Gastropoda

Neritidae Neritina virginea (L.) Nerita birmanica Phil.
Littorinidae Littorina angulifera (Lam.) Littorina melanostoma (Gray)
Cerithiidae Cerithium litteratum (Born) Cerithium patulum Sow.
Potamididae Cerithidea costata (Da C.) Cerithidea obtusa Lam.

Batillaria minima (Gmel.) Terebralia sulcata (Born)

Telescopium telescopium L.

Muricidae Murex brevifrons Lam. Murex martineanus Reeve
Melongenidae Melongena melongena (L.) Melongena pugilina Born
Ellobiidae Melampus coffeus (L.) Ellobium aurismidae L.

Melampus bidentatus Say Ellobium aurisjudae L.

Ттайа ovula (Brug.) Cassidula spec.

Detracia bullaoides (Mont.)

COOMANS 83
Pelecypoda

Arcidae Anadara notabilis (Röd.) Anadara granosa (L.)
Isognomonidae | Isognomon alata (Gmel.) Isognomon isognomon (L.)
Ostreidae Crassostrea rhizophorae (Guil.) Crassostrea parasitica (Gmel.)
Anomiidae Pododesmus rudis (Brod.) Aenigma rosea Gray
Mytilidae Brachidontes exustus (L.)

Modiolus americanus (Leach) Modiolus spec.
Veneridae Anomalocardia brasiliana (Gm.) | Paphia luzonica Sow.

Chione cancellata (L.) Meretrix meretrix (L.)
Asaphidae Asaphis deflorata (L.) Gavi togata (Desh.)
Teredinidae Teredo spec. Teredo manii (Wright)

Two families have a number of species in the mangrove area, both in the oriental
and in the occidental fauna, and they can more or less be considered as typical man-
grove mollusks: they are the Potamididae and the Ellobiidae.

LITERATURE

ABEL, O., 1926, Fossile Mangrovestimpfe. Palaeont. Zeitschr., 8: 130-139.
BERRY, A. J., 1963, Faunal zonationinmangrove swamps. Bull. Nat. Mus. Singapore,

32: 90-98.

COOMANS, H. E., 1962,

Amer. Malacol. Un., 10-11.

EDMUNDS, M.,
EDMUNDS, M.,

1962, Bivalved gastropod from Jamaica.
1963,

Berthelinia caribbea п.

“Brainwash” experiments with mollusks.

Sp.,

Ann. Rep. 1962

Nature, 195(4839): 402.
a bivalved gastropod from the

West Atlantic. J. Linn. Soc. London, Zool., 44: 731-739, pl. 1.

EDMUNDS, M.,

1964, Eolid Mollusca from Jamaica, with descriptions of two new

genera and three new species. Bull. Mar. Sci. Gulf Caribb., 14: 1-32.
GERLACH, S. A., 1958, Die Mangroveregion tropischer Ktisten als Lebensraum.

Z. Morph. und Okol. Tiere, 46: 636-730.
GOLLEY, F. B., 1960, Ecologic notes on Puerto Rican Mollusca. Nautilus, 73:

152-155.

LENDERKING, R. E.,

Caribb., 3: 273-296.

TINE | Chat Fs,

1954, Some recent observations on the biology of Littorina
angulifeva Lam. of Biscayne and Virginia Keys, Florida.

Bull. Mar. Sci. Gulf

1963, A preliminary illustrated account of mangrove molluscs from

Singapore and South-West Malaya. Malayan Nat. J.,17: 235-239, pl. 39-42.

MARCUS, E.

& MARCUS, E.

1963, Mesogastropoden von der Kiiste Sáo Paulos.

Abh. Akad. Wiss. Lit., Math. Naturw. Kl., 1963: 1-105.

MARCUS, E. & MARCUS, E.,

Zoologia, 25: 19-82.

1965, On Brazilian supratidal and estuarine snails.

МАТТОХ, N. Т., 1949, Studies on the biology ofthe edible oyster, Ostrea rhizophorae
Guilding, in Puerto Rico. Ecol. Мопорт., 19: 339-356.

McGILL, J. T., 1958, Coastal landforms of the world. Map suppl. in R. J. RUSSELL,
1959, Second coastal geography conf. Coastal Stud. Inst., Louisiana State Univ.

MORRISON, J. P. E., 1958, Ellobiid and other ecology in Florida. Nautilus, 71:
118-124.

84 PROC. THIRD EUROP. MALAC. CONGR.

ROBERTSON, R., 1960, The mollusk fauna of Bahamian mangroves. Amer. Malacol.
Un., 26: 22-23.

RODRIGUEZ, G., 1959, The marine communities of Margarita Island, Venezuela.
Bull. Mar. Sci. Gulf Caribb., 9: 237-280.

ROSEWATER, J., 1963, Problems of species analogues in world Littorinidae. Ann.
Rep. 1963 Amer. Malacol. Un., 5-6.

STEPHENS, W. M., 1962, Tree that makes land. Sea Frontiers, 8: 219-230.

USTICKE, G., 1960, Shelling in Martinique. N. Y. Shell Club Notes, 62: 5-6.

VAN STEENIS, C. G. G. J., 1962, The distribution of mangrove plant genera and its
significance for palaeogeography. Proc. Kon. Ned. Akad. Wet., ser. C, 65:
164-169.

WARMKE, С. L., 1966, Two species of the bivalve gastropod Berthelinia found in
Puerto Rico. Nautilus, 79: 139-141.

WARMKE, С. Г. € ALMODÓVAR, L. R., 1963, Some associations of marine mollusks
and algae in Puerto Rico. Malacologia, 1: 163-177.

MALACOLOGIA, 1969, 9(1): 85-91

PROC. THIRD EUROP. MALAC. CONGR.

A MALACOLOGICAL SURVEY OF THE SMALL TUSCAN ISLANDS
Folco Giusti
Institute of Zoology, Siena, Italy
INTRODUCTION

That the Tuscan Archipelago is particularly interesting canbe seen from the number
of malacological studies already done on it, including those of Issel (1866, 1872),
Gentiluomo (1868), Paulucci (1866), Pollonera (1905, 1909), Caziot (1916), Razzauti
(1917, 1936), Colosi (1920), Buttner (1926), Bisacchi (1929), Pfeiffer (1932) and Sacchi
(1957b). These studies were mostly done on malacological materials collected by
other researchers such as the explorer Giacomo Doria, the botanist Bicknell, the
paleontologist Major and the entomologist Cavanna. Although excellent, not being
specialists, it is probable that many infrequent species escaped their notice. More-
over, the main taxonomic characteristic to be considered till now has been the shell,
which often shows great variability in a harsh environment like that of small islands.

The neglect of anatomical study has led, on one hand, to unjustified subdivisions of
forms with identical anatomical characteristics as in the case of Cernuella (s.str.)
profuga (Schmidt), of Marmorana (Ambigua) argentarolae (Paulucci) and of Helicigona
(Chilostoma) planospiva occultata (Paulucci); and on the other hand, it has precluded
the identification of numerous species distinguishable only on an anatomical level.
Thus these islands require a more careful and detailed examination. The present
research is an effort to complete the prospect of the malacological peopling of each
island of the Archipelago, to correct the systematic position of each species and to
ascertain their origin and, where possible, to make biogeographic comparisons with
nearby Corsica and Sardinia, Tuscany, the Appennines and the promontory of
Argentario.

From many aspects, the promontory of Argentario can be considered as an island,
faunistically corrupted by its direct connection with the Tuscan coast and by a con-
sequent high anthropization. Even though my exploration covered only four of the six
islands of the Archipelago: Capraia, Gorgona, Giglio and Montecristo, it is possible
to reach some preliminary conclusions.

FAUNISTIC OBSERVATIONS

Among the most interesting faunistic data resulting from my research is the find-
ing of 15 species previously unknown on the Tuscan Archipelago. They are: the
brackish water species Truncatella subcylindrica (Linnaeus) found on the rocks of
the coast of Gorgona, the fresh water species Armiger crista (Linnaeus) in the pools
of “Vado del Porto” at Capraia, the humus species Hypnophila dohrni (Paulucci)
under the calcareus stones in Giglio, the rock-clinging Pyramidula rupestris (Drapar-
naud) under a group of stones near the village of Capraia, the calciophile species
Стапорира (s.str.) granum (Draparnaud) and Стапорира (Rupestrella) philippi (Can-
traine) at the base or on the surface of the rocks of the calcareous part of Giglio, the
calciophile and hygrophile Acanthinula aculeata (Miller) under the dead leaves of a
group of Ailanthus near “Cala Maestra” at Montecristo, Jaminia quadridens (Müller)
under the calcareous stones near the hill “Franco” on Giglio, Vitrea (s.str.) contracta
(Westerlund) and crystallina (Müller) the former on Montecristo and the latter on

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86 PROC. THIRD EUROP. MALAC. CONGR.

Giglio, a new species of Lehmannia I named Lehmannia caprai Giusti on Capraia and
Gorgona, Deroceras (s.str.) caruanae (Pollonera) and Hohenwartiana moitessieri
(Bourguignat) near “Cala Scirocco” at Gorgona, Testacella scutulumSowerby ubiquitous
in Capraia, Montecristo and near the harbour of Giglio and lastly Trochoidea (s.str.)
pyramidata (Draparnaud) on Gorgona and Giglio (Giusti, 1968).

There are also many species not yet recorded for the individual islands studied.
In Capraia there are ten of them, bringing the total up to twenty; eight species on
Montecristo bring its total to thirteen; twelve species on tiny Gorgona bring its total
to twenty species and, to conclude, thirteen species on Giglio make its total thirty-
eight, including Helix (Cryptomphalus) aspersa Müller,which can be found even as a
quaternary fossil in the arenous deposits (Giusti, 1968).

Undoubtedly the most interesting result was obtained from the systematic examina-
tion of the different groups of Oxychilus. These results, though incomplete since I
have not yet had the possibility of studyingthe Oxychilus of Pianosa and Giannutri, re-
vealed that there is a different species of this group of Zonitidae on each island. I
was able to distinguish the species of Gorgona, Capraia and Giglio by a study of the
genital apparatus and I named them Oxychilus (s.str.) gorgonianus Giusti, Oxychilus
(s.str.) pilula (Westerlund) and Oxychilus (s.str.) igilicus Giusti, respectively (Giusti,
1968).

It was previously thought that the species of Gorgona and Giglio were very close
either to Hyalinia guidonii De Stefani or to Hyalinia scotophila De Stefani var. notha
Paulucci from the Tuscan Appennines (Paulucci, 1886; Bisacchi, 1929), and that the
species of Capraia was very close to Hyalinia lucida Draparnaud (Razzauti, 1917).
However, the most interesting result was the finding of many adult samples of the
Zonitidae living at Montecristo. Probably the study of young samples was what led it
to be referred either to Oxychilus (s.str.) oppressus (Shuttleworth) (Forcart, 1967),
or to Oxychilus (s.str.) obscuratus (Porro) (Bisacchi, 1929). Instead, the shell clearly
reveals that we are in the presence of a new and distinct entity, as does the structure
of the genital and radular apparatuses.

I think that the peculiar structure of the shell, flattened, strongly carenated, wrinkled,
opaque and with a rhomboid buccal opening, very similar to that of certain species of
Aegopis and of some Trochomorpha and, therefore, quite different from that of any
other Oxychilus, as well as the particular radular formula 11-14 4 С 4 11-14
Ca tagte
makes the creation of a new supraspecific entity at a subgeneric level necessary.
So I named it Oxychilus (Alzonula) oglasicola Giusti (Giusti, 1968).

Lastly, I found specimens of another species of Oxychilus on the promontory of
Argentario and on Giglio and studied the anatomy of several samples from the first
spot (near Porto Ercole). This Oxychilus revealed itself very different from any
other, and particularly from Oxychilus (s.str.) oppressus (Shuttleworth) (=Hyalinia
lybisonis Paulucci) which Paulucci (1866) considered synonymous with it. So I named
it Oxychilus (s.str.) argentaricus Giusti (Giusti, 1968).

BIOGEOGRAPHICAL OBSERVATIONS

Many elements with completely different origins belong to the malacological fauna
of the Tuscan Archipelago. According to their present geonemy, they may be divided
into the following groups.

A) More or less differentiated endemic forms related to other European forms.

1) Strongly differentiated endemisms belonging to very fragmented European groups
with a wide Mediterranean geonemy.

I consider Oxychilus (Alzonula) oglasicola Giusti of Montecristo as belonging to

GIUSTI 87

this group. This species can be considered a relict, with a high degree of differenti-
ation. I also place the other species of Oxychilus present on the other islands in this
group. The above mentioned considerations and the European geonemy, which the
genus аз a whole now shows, lead us to the supposition that originally the Tyrrhenis
was populated by a strain that first became differentiated from the continental one.
Subsequently, factors of isolation, cacuminal at first and then insular, further frag-
mented it in loco.

2) Slightly differentiated endemisms belonging to European groups with a very
reduced mediterranean geonemy.

Helicigona (Chilostoma) planospira occultata (Paulucci), which is common on the
Argentario and Giglio, belongs to this group.

В) Species with a European or Euromediterranean geonemy.

Among these I mention the following species: Pomatias elegans (Miller), Helix
(Cryptomphalus) aspersa (Müller), Limax (Limacus) flavus Linnaeus, Milax (s.str.)
nigricans (Schultz), Milax (s.str.) sowerby (Férussac), Deroceras (s.str.) сатиапае
(Pollonera), Vitrea (s.str.) contracta (Westerlund), Уйтеа (s.str.) crystallina (Muller),
Vitrea (s.str.) diaphana (Studer), the fresh water species Armiger crista Linnaeus
and one brackish water species Truncatella subcylindrica Linnaeus. The presence
of fossil shells of Helix (Cryptomphalus) aspersa Miller in arenous deposits, probably
dating back to the quaternary, is particularly interesting.

This confirms the ancient settling of the species on this island, a factor which is
often difficult to determine because of the introduction of the larger snails by man,
especially for his own alimentation.

C) Mediterranean forms.

Most of the molluscs of the Tuscan Archipelago may undoubtedly be included in this
class, which may be further subdivided into:

1) Endemic species of Tyrrhenic origin.

Undoubtedly the well known Tacheocampylaea (s.str.) tacheoides (Pollonera), ubiqui-
tous on Capraia, and also the Tacheocampylaea (s.str.) elata Simonelli, quaternary
fossil on the island of Pianosa, belongtothis group. These two species, which I prefer
to keep distinguished even though they are often considered synonymous (La Greca
Sacchi, 1957; Razzauti, 1936), show a strong affinity with the other species of the genus
Tacheocampylaea that we can find in Sardinia and Corsica. The above mentioned ob-
servations and the presence in the Southern France, more precisely in the department
of Drome, of some fossil miocenic shells of Tacheocampylaea (Mesodontopsis) chaixii
(Michaud), further confirm the hypothesis of the presence of a Tyrrhenis. Besides,
they support the hypothesis of a very old, probably premiocenic, origin of a part of
the malacological fauna of Corsica, Sardinia, Pianosa and Capraia.

Also, the Cochlodina of Gorgona seems to me very interesting, even though till now
completely disregarded. This last species was first referred by Bisacchi (1929) to
Cochlodina porroi (Pfeiffer) after the examination of a couple of dead samples. I could
find it commonly enough on the walls near “Torre Vecchia” and on the bark of several
oak trees in the valley near the churchyard. An examination of these materials and a
comparison of them with the samples ofthe Paulucci collection, shows that the species
of Gorgona can be considered very near to Cochlodina küsteri (Rossmässler). In
fact, the species differs from Cochlodina porroi (Pfeiffer) which is synonymous with
Cochlodina meisneriana (Shuttleworth) in the striations ofits shells, which appear less
marked and more dense. The genital apparatus, very uniform in the genus Cochlodina,
does not give us enough characteristics to distinguish Cochlodina küsteri (Ross-
mässler) from Cochlodina meisneriana (Shuttleworth).

88 PROC. THIRD EUROP. MALAC. CONGR.

I think that we are in the presence of a group of forms, including Cochlodina küsteri
(Rossmässler, 1836) with its three varieties that are sarda (Villa, 1836), sancta
(Paulucci, 1882),), sophiae (Paulucci, 1882) and the Cochlodina meisneriana (Shuttle-
worth, 1843) with its variety porroi (Pfeiffer, 1848), all of them referable to a single
entity. This is supported by the fact that, as Paulucci (1882) and Boettger (1878)
stated, the Sardinian species, Cochlodina küsteri (Rossmässler), is present in Corsica,
and that the Corsican species, Cochlodina meisneriana (Shuttleworth), is present even
in Sardinia. Aside from the systematical problem, we have another important proof
of an ancient connection between Corsica, Sardinia andthe northern part of the Tuscan
Archipelago.

2) Forms with a central-Mediterranean geonemy.

Many species belong to this group, including Helix (Cantareus) aperta Born, Grano-
pupa (Rupestrella) philipii (Cantraine), the fresh water species Gyraulus agraulus
(Bourguignat) and Hypnophila dohrni (Paulucci). I want to draw attention to this
last species more than to the others, on which there is a rich bibliography (Sacchi,
1952, 54, 55; La Greca & Sacchi, 1957). Hypnophila dohrni (Paulucci) is a Sardinian
species inhabiting the calcareous areas near Sassari. I referred the Hypnophila I
gathered on the calcareous hill of Giglio to it rather than to the Hypnophila etrusca
(Paulucci), which inhabits the promontory of Argentario and the island of Elba where
I was able to find it recently. In fact, the species of Giglio has a more conic and less
oval shape and a weaker tooth near the exterior side of the buccal opening. These
characteristics are the same as those of the Sardinian species Hypnophila dohrni
(Paulucci). However, I think that these characteristics are not sufficient to maintain
the distinction between Hypnophila dohrni (Paulucci) and Hypnophila etrusca (Paulucci);
rather, we can consider them to be forms of the same entity.

In addition to the close relationship between the Tuscan Archipelago and Sardinia
that this situation shows, we must also keep in mind that the genus Hypnophila is also
diffused in North Africa, Sicily, the Egadi Archipelago, the Lipari island, Greece and
Dalmatia, but is lacking on the mainland of Italy. Unless we explain this geonemy with
the shaky hypothesis of a relatively recent Sicilian bridge (Jeannel, 1942; Sacchi, 1955),
it can only be justified by the well known tertiary connections between Maghreb, Sicily,
Sardinia and Tuscan Archipelago, all belonging to Tyrrhenis. The presence of forms
of Hypnophila in Greece, Albany and Dalmatia also implies a vast tertiary diffusion
that later broke up. The present geonemy is only a residue of this.

A similar but more continuous distribution is shown by Granopupa (Rupestrella)
philipii (Cantraine), which I found on the island of Giglio. In fact, this last species is
very common in Maghreb, Sicily and Sardinia, where it was found by Paulucci (1882),
in the Balkan peninsula, in Dalmatia and in many localities of southern Italy.

The finding of Marmorana (Ambigua) argentarolae forsythi (Paulucci) оп the western
side of Giglio, on the small calcareous hill named “Franco,” is also noteworthy. The
subgenus Ambigua is known to inhabit the Appennines; the species itself was only
known to live on the Argentario promontory and the islet of Argentarola. Its presence
on Giglio repeats the situation of other species that also show a close relationship
between Giglio and Argentario. It seems very likely that Giglio and Argentario were
connected over a long period during the quaternary.

3) Forms with a western-Mediterranean geonemy.

Many species belong to this group. Helicella (Xerotricha) conspurcata (Drapar-
naud), Helicella (Xerotricha) apicina(Lamarck), Trochoidea (s.str.) trochoides (Poiret),
Cochlicella acuta (Müller), Caracollina lenticula (Michaud), Papillifera (s.str.)
papillaris (Müller), Jaminia (s.str.) quadridens (Müller and lastly genus Pleuropunctum

GIUSTI 89

Germain (1929) are among the most important. But the last two are particularly sig-
nificant because they are not easily importable and are more closely bound to a par-
ticular kind of environment.

The presence of the central and southern European species Jaminia (s.str.) quadri-
dens (Miiller) on Giglio, once again shows the close connection of Sardinia and Corsica
with the southern part of the Tuscan Archipelago and provides another link in the dis-
tribution of this species from the southwestern regions of Europe to the southern Ap-
pennines (Bacci, 1953). The distribution ofthe genus Pleuropunctum is also extremely
interesting. I have found one species of this genus, Pleuropunctum micropleuros
(Paget), previously known to inhabit only Sardinia and Giglio, on the island of Monte-
cristo and on the central-southern Appennines (Giusti, 1968). Other species are found
in Algeria, Spain and southern France. It seems possible that the settlement of
Jaminia quadridens (Müller) and of Pleuropunctum micropleuros (Paget) on the Tuscan
islands was very ancient, dating back to the tertiary.

4) Forms with а north-Mediterranean geonemy and a ргеуа1еп у Italian distribution.

Among the few forms that belong to this group, there are Hygromia (s.str.) cinctella
(Draparnaud), Limax (s.str.) corsicus Moquin Tandon, Papillifera (s.str.) solida
(Draparnaud) and Hohenwartiana moitessievi (Bourguignat). The most interesting of
these is the small humus species Hohenwartiana moitessieri (Bourguignat), that I
collected on Gorgona and that closely relates the fauna of the northern part of the
Tuscan Archipelago with that of Corsica, southern France and Piedmont Alps, and
gives us another example of Tyrrhenic distribution.

5) Forms with a circum-Mediterranean geonemy.

Granopupa (s.str.) granum (Draparnaud) present throughout the Mediterranean and
in Portugal, Transcaucasus and Persia, Theba pisana(Müller) and Cochlicella barbara
(Linnaeus) can be listed among these.

D) Species with a very extensive geonemy.

Such forms are very rare, as for example the palearctic Lymnaea (Radix) peregra
Müller and the oloarctic Lymnaea (Galba) truncatula (Müller), which are not sig-
nificant because of their probable introduction by birds. Lastly, there is Lauria
(s.str.) cylindracea (Da Costa) common throughout the Mediterranean area, in Portu-
gal, France, Belgium, Norway, Crimea and Transcaucasus.

CONCLUSIONS

Oxychilus, which is represented by a distinct species on each island and is present
even as a fossil in quaternary arenous deposits at Giglio, seems to suggest the hy-
pothesis of a single peopling of the small islands of the Tuscan Archipelago. There-
fore, it seems possible that successive cacuminal and insular geographic isolations
led to differentiation by genetic drift.

It is much more difficult to coordinate the data on the other molluscs of the Tuscan
Archipelago and draw conclusions. In fact, given the notable geological differences
in the islands of the Archipelago (some calcareous, some volcanic), ecological factors
must have played a very important role in the malacological peopling of these islands,
which, as is known, is greatly influenced by the chemical composition of the environ-
ment. Therefore, it is practically impossible to say whether the calciophile forms
that inhabit Giglio, Giannutri and the Argentario promontory, where calcium abounds,
also reached the volcanic part of the Tuscan Archipelago and were subsequently
eliminated or avoided it entirely. Thus an overall view of the peopling of the Tuscan
Archipelago is very problematical.

90 PROC. THIRD EUROP. MALAC. CONGR.

Nevertheless, the permanence in loco of acertainnumber of species that seem quite
significant to me, suggests the following conclusions. The process of settling must
have taken place in several periods. The most ancient one, probably dating back to
the tertiary, was characterized by the presence of many forms over a wide area
corresponding to Tyrrhenis. Some are strictly tyrrhenic (Tacheocampylaea, Oxychilus,
Cochlodina and Hohenwartiana); others have a wider prevalently central-Mediterranean
geonemy (Hypnophila, Granopupa, Trochoidea, Caracollina, Vitrea, Hygromia, Papilli-
fera and Pomatias) and remained on these islands after the breaking up of Tyrrhenis.
During the quaternary, forms like Limax, Milax, Helix, Deroceras and Marmorana
must have arrived over the Corsican-Tuscan bridge. Lastly, other more common
forms may have arrived later in the quaternary, as well as by subsequent importation
by man, as in the case of Ferrussacia (Pegea) carnea (Risso) on the island of Pianosa.

A careful study of the Appennine malacofauna and especially that of Sardinia, which
has not been re-examined for a long time, is called for. Since the southern part of the
Tuscan Archipelago is closely related to these areas, it would be absurd and risky to
draw more detailed conclusions using only our present data on molluscs.

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FORCART, L., 1965, Rezente Land- und Süsswassermollusken der stiditalienischen
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FORCART, L., 1967, Die systematische Stellung toskanischer Oxychilus-Arten und
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GERMAIN, L., 1930, Mollusques terrestres et fluviatiles. Faune de France, 21: 1-477,
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GIUSTI 91

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Le Tacheocampylaea di Pionosa e di Capraia. Atti Soc. Tosc. Sci. Nat., 45(3):
1-4,

SACCHI, C. F., 1954, Contributo alla conoscenza dei popolamenti delle piccole isole
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Zool., 21(1): 1-40, 8 tabs., 6 figs.

SACCHI, C. F., 1955, Il contributo dei molluschi alle ipotesi del “ponte sicilianc.”
Elementi tirrenici ed orientali nella malacofauna del Maghreb. Arch. Zool. Ital.,
40: 49-181.

SACCHI, С. F., 1956, Sulla malacofauna terrestre di Pantelleria. Atti Soc. Ital. Sci.
Nat., 95: 33-44.

SACCHI, C. F., 1957b, Relazioni tra superficie insulare e mole corporea in Eobania
vermiculata (Müll.) dell’Arcipelago toscano. Boll. Zool., 24: 1-8.

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В. Comitao geol. d’Ital., 10(7/8): 193-237, 5 tabs.

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MALACOLOGIA, 1969, 9(1): 93-99

PROC. THIRD EUROP. MALAC. CONGR.

ZUR SYSTEMATIK DER GLOSSODORIDINAE DES MITTELMEERES!

HR. Haefelfinger

Naturhistorisches Museum Basel, Switzerland
Laboratoire ARAGO Banyuls-sur-Mer, France

EINLEITUNG

Im Rahmen einer Revision der Gattung Glossodoris Ehrenberg hat Pruvot-Fol 1951,
sowie später in der Faune de France 1954 “Opisthobranches”die Glossodoridinae des
Mittelmeeres bearbeitet.

Die seit gut einem Jahrzehnt an verschiedenen biologischen Stationen des Mittel-
meeres (Banyuls, Villefranche, Neapel) durchgeführten Studien an Opisthobranchia,
und die damit verbundenen regelmässigen Fänge, erlauben uns erneut auf das Problem
der Systematik der Glossodoridinae im Mittelmeer zurückzukommen. Heute steht dem
Malakologen wesentlich mehr Vergleichsmaterial zur Verfügung; Farbphotographie
und Kinematographie bieten Dokumente, welche nicht von subjektiven Eindrücken und
von den zeichnerischen Fähigkeiten des Beobachters abhängig sind. Färbung und
Musterbildung sind bei Glossodoridinae ebenso wichtige Bestimmungsmerkmale wie
Radula und Genitaltrakt. Neben dem fixierten Material sollten auch Notizen über das
Verhalten, über Zeichnung und Körperfärbung vorliegen. Für diese Arbeit wurden die
Originalveröffentlichungen der Diagnosen konsultiert.

Dank schulde ich Fräulein Dr. L. Schmekel (Neapel), G. Nicaise (Villefranche/Lyon)
und vielen anderen, welche mir Material und Unterlagen für diese Arbeit überlassen
haben.

ALLGEMEINE BEMERKUNGEN

Schon vor einigen Jahren habe ich (Haefelfinger, 1959) die Ontogenese des Zeich-
nungsmusters einiger Glossodoridinae (G. gracilis, krohni, luteorosea und tricolor)
beschrieben. Die seit diesem Zeitpunkt gefundenen Exemplare dieser Arten haben
die damals publizierten Resultate bestätigt. Im Katalog der Opisthobranchia der
Bucht von Villefranche (Haefelfinger, 1960) wurden zwei weitere Glossodoridinae als
unbestimmte Arten erwähnt. Von der einen Art konnte das einzige Exemplar als
Glossodoris valenciennesi bestimmt werden, bei der zweiten Art, welche in mehreren
Exemplaren in Villefranche und später auch in Banyuls gefunden wurde, handelt es
sich um Glossodoris messinensis.

LISTE UND SYNONYMIE DER MITTELMEER-GLOSSODORIDINAE

1. Glossodoris elegantula (Schultz-Philippi) 1844 (Doris)
Synonyme: Chromodoris elegantula Vayssiere 1913
Bemerkungen: Diese Art soll angeblich von Pruvot-Fol in Villefranche wieder
gefunden worden sein. Es ist allerdings sehr fraglich, ob es sich um eine
Glossodoris handelt. Wahrscheinlich ist es Diaphorodoris luteocincta papillata
Portmann 1959.

lVorlaufige Mitteilung.

(93)

PROC. THIRD EUROP. MALAC. CONGR.

ABB. 1. Glossodoris gracilis. a, adult; b, juvenil.
ABB. 2. Glossodoris krohni. a, juvenil; b, adult.
ABB. 3. Glossodoris luteorosea. a, juvenil; b, adult.

Der weisse Strich auf den Abbildungen entspricht einem Zentimeter Lange.

ABB.

ABB.
Grosse.

ABB.

Glossodoris

HAEFELFINGER

messinensis. a, juvenil; b, adult.

purpurea adult,

tricolor adult,

valenciennesi.

die juvenile Form unterscheidet sich nur durch die
die juvenile Form unterscheidet sich nur durch die

a, juvenil; b, adult.

PROC. THIRD EUROP. MALAC. CONGR.

Glossodoris gracilis (Rapp) 1827 (Doris)

Synonyme: Doris gracilis Delle Chiaje 1841; Doris orsinii Vérany 1846; Doris
pasinii Vérany 1846; Doris pulcherrima Cantraine 1835/40; Doris tenera Costa
1840; Doris villae Уегапу 1846; Doris villafranca Risso 1818; Chromodoris
villafranca Vayssiere 1913.

Bemerkungen: Glossodoris gvacilis ist in Färbung und Musterbildung sehr
variabel. Stadien von 5-10 mm Länge können bei oberflächlicher Beobachtung
mit Glossodoris tricolor und messinensis unter Umständen verwechselt werden.

Depot: Nat. Hist. Mus. Basel, Gastropoda Nr. 7192.

Glossodoris krohni (Verany) 1846 (Doris)

Synonyme: Doris pallens Rapp 1827 (adultes Exemplar); Chromodoris trilineata
von Ihering; ?; Doris lutescens Delle Chiaje 1841?.

Bemerkungen: Da sich das Zeichnungsmuster im Verlaufe der Entwicklung
verändert (Liniensystem wird in längliche Inseln aufgelöst) ist der Zusammen-
hang zwischen den beiden Formen erst in den vergangenen Jahren zutage
getreten. Mit einiger Sicherheit kann daher auch Doris lutescens als Synonym
betrachtet werden.

Depot: Nat. Hist. Mus. Basel, Gastropoda Nr. 7193

Glossodoris luteorosea (Rapp) 1827 (Doris)

Synonyme: Chromodoris iheringi Bergh 1879; Chromodoris luteorosea Vayssiere
1901/1913/1919; Doris parthenopeia Delle Chiaje 1841.

Bemerkungen: Diese Art hat ein sehr spezifisches Färbungsmuster, das kaum mit
einer anderen Art verwechselt werden kann.

Depot: Nat. Hist. Mus. Basel, Gastropoda Nr. 7194

Glossodoris messinensis (von Ihering) 1880 (Chromodoris)

Synonyme: Glossodoris fauntandraui Pruvot-Fol 1951.

Bemerkungen: Lange Zeit blieb diese durch von Ihering beschriebene Form ver-
schollen, respektive wurde mit g7acilis verwechselt. (Variante des Zeich-
nungsmusters). Die von Pruvot angefertigten Farbskizzen von Glossodoris
fauntandraui sind sehr ungenau. In groben Zügen stimmen sie jedoch mit
messinensis überein. Eigene Erfahrungen und Angaben von G. Niçaise haben
gezeigt, dass auch bei dieser Art ziemliche Abweichungen in Färbung und
Musterbildung auftreten können. Die Radula von fauntandraui und messinensis
stimmen ebenfalls sehr genau überein.

Depot: Nat. Hist. Mus. Basel, Gastropoda Nr. 1102

Glossodoris purpurea (Laurillard) 1831 (Doris)

Synonyme: Doris albescens Schultz-Philippi 1836/44; Doris pirainii Verany 1846;
Doris venulosa Leuckart 1828.

Bemerkungen: Glossodoris purpurea ist die einzige Glossodoridier-Art des
Mittelmeeres, welche kein Zeichnungsmuster aufweist, sie ist daher sehr leicht
zu identifizieren.

Depot: Nat. Hist. Mus. Basel, Gastropoda Nr. 7196

Glossodoris tricolor (Cantraine) 1836/41 (Doris)

Synonyme: Goniodoris coelestis Deshayes 1866; Glossodoris coelestis Mangold-
Wyss 1958; Glossodoris coelestis Pruvot-Fol 1951/54.

Bemerkungen: Beobachtungen haben gezeigt, dass die für Glossodoris coelestis
typischen Tuberkel auf der Rückenfläche nicht immer gleich stark in Erscheinung
treten, das heisst je nach Kontraktionszustand der Schnecke sind sie mehr oder
weniger ausgeprägt. Es ist daher mit Sicherheit anzunehmen, dass die Arten
tricolor und coelestis identisch sind, dakeine weiteren Unterscheidungsmerkmale
vorliegen.

Depot: Nat. Hist. Mus. Basel, Gastropoda Nr. 7195

Glossodoris valenciennesi (Cantraine) 1835 (Doris)

Synonyme: Doris elegans Cantraine 1835; Chromodoris cantrainii Bergh 1892/99;
Doris calcara Vérany 1846; Doris патай Vérany 1846; Doris picta Schultz-

HAEFELFINGER 97

ABB. 8. a, Gelege von Glossodoris gracilis; b, Verschiedene Gelege von Glossodoris
messinensis.

Philippi 1836/44; Doris scacchiana Delle Chiaje 1830/41; Doris schultzii

Delle Chiaje 1841.

Bemerkungen: Diese grósste Glossodoridierart des Mittelmeeres zeigt auch die
stärksten Variationen in Färbung und Musterbildung. Es ist daher nicht er-
staunlich, dass so viele Synonyme auftreten. Valenciennesi unterscheidet sich
jedoch in charakteristischer Weise von den Übrigen Formen des Mittelmeeres.

Depot: Nat. Hist. Mus. Basel, Gastropoda Nr. 7197.

DISKUSSION

Die meisten der von verschiedenen Autoren beschriebenen Glossodoridinae Konnten
eindeutig identifiziert werden, da einumfangreiches Vergleichsmaterial vorlag. Einzig
bei Doris lutescens Delle Chiaje bestehen noch geringe Zweifel.

98 PROC. THIRD EUROP. MALAC. CONGR.

Problematisch bleibt, wie schon erwáhnt, Glossodoris elegantula Schultz-Philippi.
Das vorhandene Aquarell zeigt uns eindeutig eine Diaphorodoris luteocincta papillata
Portmann 1959. Es ist immerhin erstaunlich, dass die von Schultz-Philippi erwáhnte
Art, mit Ausnahme eines zweifelhaften Wiederfundes durch Pruvot-Fol, bis heute
nicht mehr gesichtet wurde.

Einige Schwierigkeiten bietet die Abgrenzung und Identifizierung der blauen
Glossodoridinae des Mittelmeeres.

Typisches Merkmal fiir Glossodoris coelestis sollen Tuberkel auf dem Notum sein.
Die Beobachtung vieler Dutzende von lebenden Tieren haben deutlich gezeigt, dass
die Grósse der Tuberkel eng mit dem Kontraktionszustand der Schnecke zusammen-
hängt. Es ist durchaus möglich, dass einem Beobachter dieses Merkmal entgeht.
Vergleichen wir die Diagnose von tricolor Cantraine mit der Abbildung von coelestis
Deshayes, welche durch keine schriftliche Diagnose ergänzt wird, so stellt man eine
grosse Uebereinstimmung fest. Im Übrigen genügt die Veröffentlichung einer Abbildung
den Nomenklaturregeln gemäss nicht für die Gültigkeit einer Art.

Mit Ausnahme der Erscheinungsform können keine weiteren Merkmale verglichen
werden, da die zitierten Autoren keine anatomischen Merkmale (Radula, Genitaltrakt)
beschriebenhaben. Man geht aber nicht fehl, wenn man die beiden Namen als Synonyme
betrachtet und aus den oben erwähnten Gründen die Art mit tricolor bezeichnet. Etwas
schwieriger sind die Verhältnisse bei gracilis und messinensis, da beide Arten sehr
starke Variationen der Färbung und Musterbildung zeigen. Das gefangene Material
kann aber in frischem Zustand nach folgenden Merkmalen geschieden werden:
messinensis zeigt immer einen breiten weissen Mittelstreifen, gelegentlich etwas gelb
getönt, der als breites Band die Kiemen umfasst und zwischen den Rhinophoren nach
vorne auf der Stirn eine Art Anker bildet. Auch auf den Flanken findet man neben
feineren Linien ein breites weisses Band. Selbst juvenile Exemplare zeigen dieses
Merkmal, nur etwas weniger deutlich, da auch junge gracilis eine weisse Mittellinie
aufweisen und sich das arttypische dorsale Liniensystem erst im Verlaufe des
Wachstums bildet (Haefelfinger 1959).

Der wesentlichste Unterschied besteht sicher in bezug auf Gelege und Larvalent-
wicklung. Glossodoris messinensis produziert ein Laichband mit vielen, relativ
kleinen Eiern, aus denen immer Veliger schlüpfen, welche im Pelagial eine Meta-
morphose durchlaufen. Glossodoris gracilis hingegen legt einen Laich mit wenigen,
grossen Eiern ab, der Veliger durchläuft die Metamorphosestadien im Ei drin und es
schlüpft eine winzige Schnecke von kaum Millimeterlänge. Die von Pruvot-Fol 1941/54
gegebene Synonymie von gracilis bedarf also einiger Korrekturen. Gracilis und
messinensis sind zwei verschiedene Arten, tricolor und coelestis sind Synonyme und
bilden eine dritte Art von blauen Glossodoridiern.

Die vierte blaue Glossodoridier-Art, Glossodoris valenciennesi, zeigt sicher die
grössten Variationen der optischen Gestaltung. Der Farbton des Körpers schwankt
zwischen blau und grün bis zur intensiven satten Farbe.Die Farbe des sehr variab-
len Zeichnungsmusters variert von weiss bis gelb. Junge Exemplare können jedoch
am breiten weissen Notumrand, die adultenam welligen Notumrand gut erkannt werden.
Dieser Variabilität wegen ist es begreiflich, dass valenciennesi Anlass zu vielen
Artschöpfungen gab.

LITERATUR

BERGH, R., 1877, Kritische Untersuchungen der Ehrenberg’schen Doriden. Jb. dt.
Malakozool. Ges., 4: 45-76.

BERGH, R., 1879, Neue Chromodoriden. Malakozool. Bl. N. F., 1: 87-116.

BERGH, R., 1892, Die cryptobranchiaten Dorididen. Zool. JB. 6: 103-144.

HAE FELFINGER 99

BERGH, R., 1899, Nudibranches et Mersenia provenant des Campagnes de la
Princesse-Alice. Rés. Camp. Sc. Monaco, 14.

CANTRAINE, F., 1835, Diagnose de quelques éspèces nouvelles de Mollusques.
Bull. Acad. Sc. Bruxelles, 2: 383-386.

CANTRAINE, F., 1841, Malacologie méditerrenéenne et littorale I. Nouv. Mém.
Acad. R. Sci. Bruxelles, 13: 46-94.

CHIAJE, ST. DELLE, 1823, Mémorie su la storia e notomia degli animali senza
vertebri. I (Taf.), II (Text).

CHIAJE, ST. DELLE, 1841, Descrizione e notomia degli animali invertebrati della
Sicilia citeriore, Napoli.

COSTA, A., 1840, Statistica fisica e economica dell’isola diCapri II, Neapel.

DESHAYES, A., 1866, Tafel in Frédol: Le Monde de la Mer, Pl. XVII.

FORBES, E., 1844, Report on the Mollusca and Radiata of the Aegean Sea, and on
their distribution. XII. Report Brit. Assoc. Adv. Sci.

HAEFELFINGER, HR., 1959, Remarques sur le dévelopement du dessin de quelques
Glossodoridiens. Rev. Suisse Zool., 66: 309-315.

HAEFELFINGER, HR., 1960, Catalogue des Opisthobranches de la Rade de Ville-
franche-sur-Mer et ses environs (A.M.). Rev. Suisse Zool., 67: 323-351.

IHERING, H. von, 1880, Beitráge zur Kenntnis der Nudibranchier des Mittelmeeres
Г. Malakozool. Bl. М. F., 2: 57-112.

LEUCKART, F. S., 1828, Breves animalium quorundam maxima ex parte marinorum
descriptiones. Heidelberg.

PHILIPPI, R. A., 1836, In Schultz-Philippi. Enumeratio molluscorum Siciliae I.
Berlin.

PHILIPPI, R. A., 1844, In Schultz-Philippi. Enumeratio molluscorum Siciliae I.
Berlin.

PRUVOT-FOL, A., 1951, Etudes des Nudibranches de la Méditerranée. Arch. Zool.
Exp. et gen., 88: 1-80.

PRUVOT-FOL, A., 1951а, Révision du genre Glossodoris Ehrenberg. J. Conch.,
Paris, 41: 76-164.

PRUVOT-FOL, A., 1953, Etude de quelques Opisthobranches de la cóte atlantique du
Maroc et du Sénégal. Trav. Inst. Sc. Chérif., 5: 1-93.

PRUVOT-FOL, A., 1954, Opisthobranches. Faune de France, 58. Paris.

RAPP, W., 1827, Ueber das Molluskengeschlecht Doris und Beschreibung einiger
neuer Arten desselben. Nov. Acta Acad. Lep. Carol. Nat. Cur., 13: 515-522.

RISSO, A., 1826, Histoire naturelle de l’Europe méridionale, 4. Paris.

SCHMEKEL, L., 1968, Ascoglossa, Notaspidea und Nudibranchia im Litoral des
Golfes von Neapel. Rev. Suisse Zool., 75: 103-155.

VAYSSIERE, A., 1902, Recherches zoologiques et anatomiques sur les Opistho-
branches du Golfe de Marseille. Ш. Nudibranches. Ann. Mus. Hist. Nat,
Marseille, 6.

VAYSSIERE, A., 1903, Id. Supplément. Ann. Mus. Hist. Nat. Marseille, 8.

VAYSSIERE, A., 1909, Note sur une anomalie tentaculaire chez un Chromodoris
elegans Cantraine. Ann. Sci. Nat. Zool., 10: 109-110.

VAYSSIERE, A., 1913, Mollusques de la France. Enc. Scientifiques Paris.

VERANY, J. B., 1846, Catalogo degli animali invertebrati del Golfo di Genova e
Nizza. Genova.

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MALACOLOGIA, 1969, 9(1): 101-109
PROC. THIRD EUROP. MALAC. CONGR.

FUNCTIONAL ANATOMICAL ASPECTS OF THE
OVOTESTIS OF LYMNAEA STAGNALIS

J. Joosse and D. Reitz

Department of Zoology, Free University,
Amsterdam, The Netherlands

ABSTRACT

During investigations on the endocrine aspects of reproduction in the fresh-
water pulmonate snail Lymnaea stagnalis (Linnaeus), the ovotestis of this
species was studied. In order to determine the general structure of the ovo-
testis a plastic model was prepared from the gonad of an adult specimen. The
number of acini appeared to be 21. Their shape and size showed a great vari-
ability. The number of yolk containing oocytes varied from 16-91 per acinus.
The total number of oocytes in this specimen was about 1000.

The structure of the acini was studied by the light- and phase-contrast micro-
scope. The germinal epithelium of the acini consists of ciliated cells, and cells
with microvilli and lipid droplets. Most probably both the sex and the nurse cells
arise from the germinal epithelial ring. This is a narrow rim of cells, which
borders the germinal epithelium against the area of developing sex cells.

The female cells remain in close contact with the basal lamina of the acinus
wall. A motile phase is followed by a sessile vitellogenetic phase, during which
the oocyte is surrounded by a number of follicle cells.

The male sex cells are continuously in contact with the Sertoli cells. The
Sertoli cells form an epithelial layer, which divides the lumen of the acinus in a
female and a male compartment.

Spermiation begins with the enlargement of the Sertoli cell. Then the cyto-
plasmic remainders of the spermatids are absorbed by the Sertoli cell. At the
same time the spermia start their free life. After spermiation the Sertoli cells
do not die. They remain at their position in the epithelial layer. Most probably
they have now a phagocytotic function, as they show cytoplasmic stalks projec-
ting into the lumen of the acinus. In these stalks groups of granules with a lyso-
somal structure are found.

The plastic model of the ovotestis and a similar model of a single acinus were
used to investigate the location and arrangement of the developing sex cells in the
acini. The sessile oocytes appeared to be present in a region called the vitello-
genetic area. This area of the acinus wall is apposed to the digestive gland. A-
round this areathe spermatogenetic zone is present, in which the male cells are
found. This zone is bordered by the germinal epithelial ring.

With regard to the arrangement of the sex cells in the acini of Lymnaea stag-
nalis, a hypothesis is put forward. In this hypothesis a primary role is at-
tributed to the digestive gland.

INTRODUCTION

In the literature several times attention has been paid to the gonad of the hermaphro-
dite freshwater snail Lymnaea stagnalis (Linnaeus) (Gastropoda, Pulmonata, Basom-
matophora) (ARCHIE, 1941; BRETSCHNEIDER, 1948a,b; BRETSCHNEIDER & RAVEN,
1951; AUBRY, 1962; JOOSSE, 1964). Among these papers the thorough description of
the histology of the ovotestis of L. stagnalis lillianae given by ARCHIE, is of special
interest. Data regarding the electron microscopy and histochemistry of oogenesis
has been presented by RECOURT (1961) and UBBELS (1968).

(101)

102 PROC. THIRD EUROP. MALAC. CONGR.

During our investigations on the endocrine aspects of reproduction, the anatomy of
the ovotestis under different experimental conditions has been studied (JOOSSE, 1963,
1964, 1967; JOOSSE, et al., 1968). Our interest is primarily focused on problems like:
the site of origin of the sex cells, the role of the nurse cells and the mechanism of
ovulation and spermiation. Some of the results obtained from these investigations
are presented in this paper.

MATERIALS AND METHODS

Adult snails (shell height 27-34 mm) bred in the laboratory or collected in the field,
were dissected after decapitation.

For light microscopy the entire ovotestis surrounded by the digestive gland was
fixed in Stieve’s sublimate, upgraded in ethanol and amylacetate and embedded in
paraffin wax (т.р. 58° С). Serial sections (thickness 5 or 154) were cut, and stained
with Gomori’s chrome-hematoxylin-phloxin method.

For phase-contrast and electron microscopy glutaraldehyde and OsO4 fixed, and
Epon 812-embedded material (PEASE, 1964) was used. The thickness of the sections
for phase-contrast microscopy was 2и.

For preparing a model of the ovotestis serial sections (thickness 154) were cut from
the ovotestis of an adult specimen (shell height 28 mm). Every second section was
photographed (magn. 66x). The acini and the efferent ducts of the ovotestis were out-
lined on transparent sheets of PVC-plastic of appropriate thickness (2 mm). The
areas concerned were cut out and joined together with a suitable adhesive. Ina
similar way a second model was prepared of a single acinus using 2y thick Epon-
sections at a magnification of 118x.

GENERAL STRUCTURE OF THE OVOTESTIS

The ovotestis of Lymnaea stagnalis is situated in the top of the shell. It is sur-
rounded by the digestive gland, except at the central columellar side. From the study
of the model of the ovotestis (Fig. 1)it appeared that its shape is highly irregular.

The ovotestis consists of a number of blind sacs called acini. As is shown in Figs.
1, 2 and 3 their shape is also irregular, due to folds of the wall. The folds divide the
acinus in several compartments, which often have been considered as single acini.
Thus, ARCHIE (1941) estimated the number of acini in Lymnaea stagnalis lillianae at
about 100. However, when an acinus is defined as an irregular blind sac, having a
secondary vas efferens (Fig. 3), then the reconstructed ovotestis appears to consist
of only 21 acini.

The acini are divided into 2 groups. The secondary vasa efferentia of each group
fuse to a primary vas efferens, which join to form the spermoviduct.

The acini show a great variability of size. Apparently the number of gametes pro-
duced by them is also different. In the reconstructed specimen the number of yolk

FIG. 1. This is a photograph of a part of the plastic model of an ovotestis. 10 acini can be
seen. On acinus 3 a primary vas efferens is visible. The location of oocytes is indicated by
black dots. Note the difference in size of acinus 6 and 7. (Magnification 30x)

FIG. 2. This is a photograph of the plastic model of a single acinus. White: vitellogenetic
area. Black: spermatogenetic zone. Dotted area: vas efferens. This side of the acinus is ap-
posed to the digestive gland. (x45)

FIG. 3. The same plastic model photographed from the side which is apposed to another aci-
nus (cf. Fig. 2). Black: spermatogenetic zone. Dotted area: germinal epithelium, except the
secondary vas efferens at the upper right side. Below: two cut surfaces. (x45)

103

JOOSSE and REITZ

104 PROC. THIRD EUROP. MALAC. CONGR.

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containing oocytes varied from 16-91 per acinus. The total number of oocytes in
this ovotestis was about 1000.

THE GERMINAL EPITHELIAL RING

In Fig. 4 a sheme of a longitudinal section through an acinus is presented. The
epithelium of the (secondary) efferent duct is continuous with the epithelium lining a
large part of the lumen of the acinus. In literature this layer of cells is called the
germinal epithelium. In this epithelium two cell types can be distinguished: ciliated
cells and cells with microvilli. The latter contain lipid droplets. The epithelium is
separated from the underlying connective tissue by a basal lamina, which extends
outside the region of the germinal epithelium around the entire acinus.

The germinal epithelium is bordered against the area of developing sex cells by a
narrow rim of epithelial cells. This closed rim has an irregular course around the
wall of the acinus. It is proposed to call this rim the germinal epithelial ring (Figs.
4 and 6). From this structure apparently all cells involved in gametogenesis originate
(cf., BARTH € JANSEN, 1960, 1962). These cells are the spermatogonia, oogonia and
their nurse cells. To avoid misunderstanding the nurse cells of the female sex cells
are called follicle cells and those of the male sex cells Sertoli cells.

MOTILITY OF THE DEVELOPING SEX CELLS

BARTH & JANSEN (1962) described the origin of oogonia and follicle cells from the
germinal epithelium in Australorbis glabratus. Each oogonium accompanied by one
follicle cell moves to a more distal position on the acinus wall. There the oogonia

JOOSSE and REITZ 105

become sessile, and the follicle cell gives rise to a follicle, consisting of a fixed
number of cells around an oocyte (RAVEN, 1963). Then vitellogenesis starts.

In Lymnaea similar phenomena are described by BRETSCHNEIDER € RAVEN (1951).
The origin of the follicle cells in this species, however, has not been studied in detail.

As soon as the female sex cells have arisen from the germinal epithelial ring, they
are always in close contact with the nurse cell and the basal lamina of the acinus wall,
but they do not contact each other (Fig. 4).

The male sex cells are continuously in contact with the Sertoli cells. In Lymnaea
stagnalis the Sertoli cells are in contact with the basal lamina only at those places
where no female cells are present. However, they keep always contact with each
other, thus forming an epithelial layer of male nurse cells. This layer divides the
lumen of the acinus in a male and a female compartment (Figs. 4 and 5).

As the new Sertoli cells arise from the germinal epithelial ring, the cells with later
stages of the male sex cells are always more distally located in the epithelium (Fig. 4).

SPERMIATION

MERTON (1924, 1926, 1930) suggested that in gastropods the sperm cells beeome
motile and lose their contact with the Sertoli cells after the passage of cytoplasmic
globules originating from the Sertoli cells (“Kinoplasma-kugeln”) along the tails of
the spermatids. However, BARTH € JANSEN (1960) described the reverse in Austra-
lorbis glabratus: the cytoplasmic globules inthe Sertoli cells represent the remainders
of the cytoplasm of the spermatids.

Similar phenomena were observed in sections of the ovotestis of Lymnaea stagnalis.
At the end of the spermiogenesis, spermiation begins with the enlargement of the
Sertoli cells. The heads of the spermia get scattered. Each sperm head is connected
with a cytoplasmic globule. These globules are absorbed by the Sertoli cells and the
sperm cells start their free life (Figs. 7 and 8).

THE ROLE OF THE SERTOLI CELLS AFTER SPERMIATION

ARCHIE (1941) described in the ovotestis of Lymnaea stagnalis cells filled with
cytoplasmic globules which she called gland cells. She attributed to them a secretory
function. Apparently these cells are Sertoli cells just after spermiation, the globules
representing the cytoplasmic remainders of the spermatids (Fig. 8). Gradually the
cytoplasmic globules are replaced by a group of small and dense granules (Figs. 9
and 10). These granules become situated in a bulbshaped cytoplasmic stalk of the
Sertoli cell which extends into the lumen of the acinus. From a preliminary electron
electron microscope study the granules appeared to have a lysosomal structure. In
light microscope sections the presence of vacuoles containing different kinds of
material in the cytoplasmic stalk was established. Thus, probably the Sertoli cells
in this phase get a specialized phagocytotic function.

The spermiated Sertoli cells do not die, but keep their position in the epithelium
(Fig. 5). The survival of the Sertoli cells is easily demonstrated in the old snails
fixed during winter, in which a great number of Sertoli cells covers the “bottom” of
the acini.

THE VITELLOGENETIC AREA AND THE SPERMATOGENETIC ZONE
In literature (e.g., ARCHIE, 1941; AUBRY, 1962; BARTH & JANSEN, 1962) itis

generally accepted that in pulmonates the sex cells inorder to ripen, move to the
“bottom” of the acinus. Since it appeared from our model that the acini have a highly

106 PROC. THIRD EUROP. MALAC. CONGR.

irregular shape, it seemed worthwhile to investigate in more detail the location and
arrangement of the developing sex cells in the acini of Lymnaea stagnalis.

То this end the position of those oocytes having a size above 904, was indicated on
the surface of the plastic reconstruction of the ovotestis (Fig. 1). These oocytes
represent the greater part of the yolk-containing oocytes. Remarkably, the oocytes
appeared to be located only on those parts of the wall of the acini which are apposed
to the lobes of the digestive gland. They were completely absent on parts of the acini
which border other acini or the columella.

Futhermore, on the model of the single acinus the location of the (sessile) female
cells, the male cells and the germinal epithelium were indicated in detail (Figs. 2
and 3). Again from this model it became apparent that the position of the sessile
oocytes is restricted to those parts of the acinus wall apposed to the digestive gland.
Moreover, it appeared that this region is not occupied by oogonia or male sex cells.
Therefore it is proposed to call this area the vitellogenetic area.

The male sex cells appeared to be present in a spermatogenetic zone which sur-
rounds the area of the sessile oocytes (Figs. 2, 3 and 4). In contrast to the vitello-
genetic area the spermatogenetic zone has a rather constant width (+ 2204). In cross
sections it is usually represented by 5Sertoli cells: 3 with spermatogonia or spermato-
cytes, and 2 with spermatids. Spermiation occurs at the border of the vitellogenetic
area. The spermatogenetic area is bordered by the germinal epithelial ring.

From these results the following hypothesis is put forward. The arrangement of
the sex cells in an acinus of Lymnaea stagnalis is determined primarily by the diges-
tive gland. The size of the surface area of an acinus which is apposed to the lobes
of the digestive gland determines the shape and size of the vitellogenetic area. The
mode of action of the digestive gland in this respect is unknown, but a nutritive role
seems plausible.

The location of the spermatogenetic zone is determined by the vitellogenetic area,
as it follows closely the outline of this area.

The spermatogenetic zone in its turn determines the outline of the germinal epi-
thelial ring. The remaining part of the acinus wall consists of inactive germinal
epithelium.

FIG. 5. Section through an acinus, in which the epithelial layer of Sertoli cells after spermi-
ation is cut. Moreover the vitellogenetic area apposed to the digestive gland can be seen. Cs:
cytoplasmic stalks of Sertoli cells after spermiation; dg: digestive gland; f: follicle cell; oc:
oocyte; og: oogonium. (x180)

FIG. 6. Cross section through the germinal epithelial ring. ge: germinal epithelium; ger:
germinal epithelial ring. (x420)

FIG. 7. Section through a Sertoli cell with spermatids, and a spermiating Sertoli cell. aw:
acinus wall; s: spermia with cytoplasmic globules; sc: spermiating Sertoli cell; st: Sertoli
cell with spermatids. (x480)

FIG. 8. Sertoli cell just after spermation. The cytoplasm is filled up with a great number of
cytoplasmic globules (“Kinoplasmakugeln”). cg: cytoplasmic globules; n: nucleus of Sertoli
cell. (х480)

FIG. 9. Section through a group of spermiating sperm cells, and a Sertoli cell after spermi-
ation, in which a group of granules can be seen, situated in a long cytoplasmic stalk. gg: group
of granules; s: spermiating sperm cells; sc: Sertoli cell after spermiation. (x480)

FIG. 10. Section through an oocyte covered by the epithelial layer of Sertoli cells. Three
cytoplasmic stalks each with a group of granules, and one nucleus of a Sertoli cell can be seen.
(x480)

JOOSSE and REITZ 107

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108 PROC. THIRD EUROP. MALAC. CONGR.

On the basis of this hypotheses itis evident that the oogonia have to move from their
site of origin to an area of the acinus wall which is apposed to the digestive gland.

In many species of pulmonates the gonad is surrounded by the digestive gland. To
support the hypothesis of the relation between gonad and digestive gland, further studies
are needed to demonstrate the location of the vitellogenetic areas in other pulmonates.
In planorbid snails the ovotestis is located caudally to the digestive gland. Never-
theless these species have clear vitellogenetic areas (BARTH & JANSEN, 1962). Per-
haps here a favoured blood supply of these areas is the primary factor.

ACKNOWLEDGEMENTS

Thanks are due to Miss W. Roolvink for technical assistance, to Mr. С. van Groenigen
and Mr. J. H. Huysing for preparing the photographs, to Mr. G. W. H. van den Berg
for drawing the figure, and to Dr. H. H. Boer for his valuable assistance in the prepa-
ration of the manuscript.

LITERATURE CITED

ARCHIE, V. E., 1941, The histology and developmental history of the ovotestis of
Lymnaea stagnalis lillianae. Thesis Univ. Wisconsin.

AUBRY В., 1962, Etude de l’hermaphrodisme et de l’action pharmacodynamique
des hormones de Vertébrés chez les Gastéropodes Pulmonés. Archs. Anat.
microsc. Morph. Exp. (Suppl.) 50: 521-602.

BARTH, R. & JANSEN, G., 1960, Ueber den Begriff “Kinoplasma” in der Spermio-
genese von Australorbis glabratus olivaceus (Mollusca, Pulmonata, Planorbidae).
Mem. Inst. Oswaldo Cruz, 58: 209-228.

BARTH, В. € JANSEN, G., 1962, Beobachtungen tiber die Entwicklung und Ernáhrung
der Eizellen von Australorbis glabratus olivaceus (Gastropoda, Pulmonata, Planor-
bidae). Ann. Acad. Brasil. Ciencias, 34: 381-389.

BRETSCHNEIDER, L. H., 1948, Insemination in Limnaea stagnalis. Proc. K. ned.
Akad. Wet. (C), 51: 358-362.

BRETSCHNEIDER, L. H., 1948b, The mechanism of oviposition in Limnaea stagnalis.
Proc. K. ned. Akad. Wet. (C) 51: 616-626.

BRETSCHNEIDER, L. H. € RAVEN, С. P., 1951, Structural and topochemical changes
in the egg cells of Limnaea stagnalis L. during oogenesis. Archs. néerl. Zool.,
10: 1-31.

JOOSSE, J., 1963, The dorsal bodies and neurosecretory cells of the cerebral ganglia
oí Lymnaea stagnalis L. (a preliminary note). Gen. Comp. Endocrinol., 3: 709.

JOOSSE, J., 1964, Dorsal bodies and dorsal neurosecretory cells of the cerebral
ganglia of Lymnaea stagnalis L. Archs. néerl. Zool. 16: 1-103.

JOOSSE, J., 1967, Gametogenesis and oviposition in Lymnaea stagnalis L. during
starvation and irradiation treatments. Gen. Comp. Endocrinol., 9: 511.

JOOSSE, J., BOER, M. H. € CORNELISSE, С. J., 1968, Gametogenesis and oviposi-
tion in Lymnaea stagnalis as influenced by Y-irradiation and hunger. Symp.
Zool. Soc. Lond., no, 22: 213-235.

MERTON, H., 1924, Lebenduntersuchungen an den Zwitterdrtisen der Lungenschnecken.
Ein Beitrag zur Plasma- und Spermienbewegung. Z. Zellen-Gewebelehre, 1:
671-687.

MERTON, H., 1926, Die verschiedenartige Herkunft des Kinoplasmas der Samen-
zellen. Eine Parallele zur Nährstoffversorgung des wachsenden Eis. Biol. Zbl.,
46: 650-678.

MERTON, H., 1930, Die Wanderungen der Geschlechtszellen in der Zwitterdrüse

JOOSSE and REITZ 109

von Planorbis. Z. Zellforsch. Mikr. Anat., 10: 527-551.

PEASE, D. C., 1964, Histological techniques for electron microscopy, 2nd ed. New
York: Academic Press.

RAVEN, C. P., 1963, The nature and origin of the cortical morphogenetic field in
Limnaea. Devl. Biol., 7: 130-143.

RECOURT, A., 1961, Electronenmicroscopisch onderzoek naar de oogenese bij
Limnaea stagnalis L. Thesis, Utrecht.

UBBELS, G. A., 1968, A cytochemical study of oogenesis in the pond snail Limnaea
stagnalis. Thesis, Utrecht.

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MALACOLOGIA, 1969, 9(1): 111-119
PROC. THIRD EUROP. MALAC. CONGR.
FAUNENGESCHICHTLICHE UNTERSUCHUNGEN IM KARPATENBECKEN
E. Krolopp

Ungarische Geologische Anstalt
Budapest, Ungarn

Beztiglich der faunengeschichtlichen Untersuchungen eines Gebietes spielt die
Molluskenfauna eine wichtige Rolle. Die kalkhaltigen Schalen der Mollusken werden
leicht fossilisiert, dementsprechend kommen ihre Reste in den Sedimenten gewóhnlich
in grossen Mengen allgemein verbreitet vor. Deshalb kónnen wir den Ursprung und
die Entfaltung einer Molluskenfauna eines gegebenen Gebietes nicht nur theoretisch,
sondern auch auf Grund konkreter Tatsachen verfolgen. Ähnliche Möglichkeiten finden
wir - soweit es Festlandfaunen anbelangt - nur noch bei Wirbeltieren.

Im hinblick auf das Verfolgen der einzelnen Phasen der Faunengeschichte und das
Entstehen der heutigen Fauna ist dem Pleistozän besonderes Gewicht beizumessen.
Besondere Bedeutung für die Faunengeschichte besitzen die klimatischen Änderungen
dieser Zeit, die das Faunenbild umgestalteten. Daraus folgt, dass wir die meisten
Angaben in bezug auf die Ausbildung der Molluskenfauna eben aus der Untersuchung
der pleistozänen Fauna erhalten werden.

Infolge seiner zentralen Lage ist Ungarn faunengeographisch ein Gebiet von aus-
schlaggebender Bedeutung im Karpatenbecken. Deshalb sind die faunengeschicht-
lichen und faunistischen Ergebnisse der Untersuchungen auch ausserhalb der Landes-
grenzen gültig. Faunengeschichtliche Angaben sind überhaupt jene, die wir auf das
ganze Gebiet des Beckens als gültig betrachten können wenn man die Gebiete des
höheren Berglandes am Beckenrande ausser acht lässt.

Die Angaben hinsichtlich der Ausbildung und der Entfaltung unserer Mollusken-
faunen hat L. Soös, der Nestor der ungarischer Malakologen zusammengefasst (Soös,
1926). In diesem Werk beschäftigte sich der Verfasser vornehmlich mit den tertiären
Wurzeln unserer Fauna. Der Meinung der damaligen Monoglacialisten entsprechend
hat er die älteren pleistozänen Faunen als “präglacial” bezeichnet und nur die Würm-
Periode als Pleistozän registriert.

Bis zum Il. Weltkrieg wurden unsere Kenntnisse hauptsächlich durch die Unter-
suchungen von M. Rotarides mit vielen Angaben über die pleistozäne Fauna bereichert
(Rotarides, 1931, 1936). Diese Angaben beziehen sich aber überwiegend auf die Löss-
fauna des Würm.

Nach dem II. Weltkrieg, hauptsächlich in den Jahren nach 1950, nahmen die mala-
kologischen Untersuchungen wieder einen Aufschwung. Die allgemeine Verbreitung
der feinstratigraphischen und der Schlämmungs-Methoden haben auf dem Gebiet der
Paläontologie grosse Mengen auch für die quantitative Auswertung geeignetes pliozänes
und pleistozänes Mollusken-Material geliefert. Dies ermöglichte eine quantitative
Betrachtungsweise der Faunen-Untersuchungen. Besonders die altpleistozäne Fauna
lieferte viele neue Angaben. Soos kannte nämlich nur drei “präglaziale,” also Vor-
Wiirm-Faunen. Auf Grund der vom Verfasser untersuchten altpleistozánen und jüngeren
interglazialen Faunen hat sich die Zahl der aus Ungarn bekannt gewordenen pleisto-
zänen Arten auf 32 erhöht, und erreicht gegenwärtig171. Diese Zahl ist auch im Ver-
gleich zu der rezenten Molluskenfauna mit 213 Arten genug hoch.

Wichtigere faunengeschichtliche Angaben über das Karpatenbecken ausserhalb
Ungarns kennen wir nur aus der Südslowakei, durch die Arbeiten von V. LoZek; diese
beziehen sich jedoch auf Molluskenfaunen der höheren Gebirge des Beckenrandes
(Lozek, 1964b).

(111)

112 PROC. THIRD EUROP. MALAC. CONGR.

Selbstverstandlich wäre es noch voreilig, über die Ausbildung und Entfaltung der
Molluskenfauna des Karpatenbeckens eine eingehende und endgültige Zusammenfassung
zu geben. Für die vorliegende Arbeit hat sich der Verfasser bloss das Zitieren teil-
weise noch nicht publizierter neuer Angaben der letzten 20 Jahre zum Ziel gesetzt.

Den Grundstock unserer Fauna bildet der im zweiten Teil des Tertiärs in ganz
Zentral-Europa verbreitete südliche Faunen-Typus, in dem schon einige der heutigen
Arten auftreten. In dieser Beziehung ist das Karpatenbecken ein recht ungünstiges
Gebiet; während wir z.B. aus Deutschland die klassischen Vorkommen dieser Fauna
kennen, sind bei uns marine Sedimente vorherrschend und die terrestrische Fauna
fehlt beinahe ganz.

Im Pliozän war das Karpatenbecken vom brakischen Pannon-See bedeckt, aus dem
nur die höheren Gebirge emporragten. Wir kennen dagegen viele Fundstellen mit
Süsswasser- und Landschnecken-Fauna des Mittel-Pliozán, vom Ende desOber-Pannon,
in dem sich die Auffüllung des Pannon-Sees und dessen Aufteilung vollzog. Feinstra-
tigraphische Untersuchungen dieser Funde durch F. Bartha vermehrten die Zahl der
kleinwüchsigen Arten, die wir in unserem Lande bis zum Tertiär verfolgen können
(Bartha, 1954, 1955). Derzeit kennen wir 41 solche Arten, doch wird die Zahl dieser
Formen noch höher, wenn wir die vorher als ausgestorben bezeichneten, aber von den
rezenten Vertretern nicht grundlegend abweichenden Arten (wie Vertigo callosa,
Vallonia subpulchella) an Hand uns zur Verfügung stehenden quantitativen Materials
revidieren. Ich glaube, eine Revision würde zeigen, dass viele als tertiär beschriebene
Arten mit rezenten ident sein werden.

Eine merkwürdige Eigenschaft der oberpannonischen Faunen ist, dass sie relativ
viele charakteristische Arten des offenen, trockenen Gebietes führten (z.B. Abida
frumentum, Truncatellina cylindrica, Vallonia costata). Das Karpatenbecken zeigte
damals einen ausgeprägteren kontinentalen Charakter als die Umgebung.

Vom oberen Abschnitt des Pliozäns haben wir recht wenig Angaben. In dem Gebiet
des Flussystems, das sich an Stelle des Pannonischen Sees bildete, kommen aus Tief-
bohrungen einige ornamentierte Unio-Funde, Viviparus- und Valvata-Gehäuse vor, die
mit den levantinen Arten von Slawonien Verwandtschaft zeigen. Neben ihnen finden
wir auch Arten, die noch heute leben. Die Landschnecken-Fauna ist noch kaum be-
kannt, am interessantesten ist eine nochnicht genaubestimmte Cochlostoma.

Sehr wenige Angaben stehen uns vom Anfang des Pleistozáns zur Verfiigung. In
der fluviatilen Fauna des Gtinz tritt der aus den Tiefbohrungen der Grossen Tiefebene
bekannte und im Mittleren Pleistozán ausgestorbene Viviparus böckhi zuerst auf. Die
Sússwasser-Fauna zeigt ausser dem erwähnten endemischen Viviparus, sowie Hydrobia
longaeva, Corbicula fluminalis, modernes Gepráge. Unter den Landschnecken finden
wir wieder Steppen-Arten; hier erscheint auch die Art Helicella hungarica. Die
taxonomischen Beziehungen dieser bei uns auch jetzt lebenden Art zu H. striata
müssen noch geklärt werden. |

Die nächste Periode ist der Zeitabschnitt, dessen Molluskenfauna uns infolge meiner
Untersuchungen der letzten Jahre ausreichend bekannt ist. Im Gebiet der Haupt-
bruchlinie längs der Donau und hauptsächlich in der Umgebung von Budapest brechen
laue und heisse Quellen auf. Einige von diesen waren schon während des Pleistozäns
tätig, was zur Bildung umfangreicher Travertin- und Kalkschlamm-Lager geführt hat.
Es war an vielen Fundstellen in den Kalkschlammschichten möglich, denen früher
keine besondere Aufmerksamkeit gewidmet wurde, eine reiche Wirbeltier- und
Molluskenfauna zu sammeln. Die paläontologischen Angaben beweisen, dass sich
diese Sedimente grösstenteils im Günz-Mindel-Interglazial und Mindel-Glazial ab-
gelagert haben. Aus dieser Zeitspanne konnten wir im ganzen 90 Arten nachweisen
(Krolopp, 1961).

Nachdem es sich um Sedimente handelt die in Thermen abgelagert wurden, besteht

KROLOPP 113

die Wasserschnecken-Fauna infolge des speziellen Milieus meistens aus thermophilen
Formen, die von den Stammformen einigermassen verschiedene unddem Warmwasser
angepasste Formen der Kaltwasser-Arten darstellen. Man kann als solche folgende
erwähnen: Theodoxus prevostianus, Fagotia acicularis audebartii, Bithynia tentaculata
thermalis. Dazu kommen noch einige eurytherme Arten. Ein merkwürdiges Vorkom-
men stellt Melania tuberculata dar, die heute in der Umgebung des Mittelmeeres lebt.

Die Landschnecken-Fauna des Zeitabschnittes kennen wir schon besser. Im Günz-
Mindel-Interglazial zeigt sich ein interessanter Gegensatz. Zum Teil besteht die
Fauna aus Arten, die auch heute noch in dieser Umgebung leben. Anderseits kommen
einige Schon ausgestorbene Artenvor. Diese sind: Gastrocopta serotina und Zonitoides
sepultus. LoZek betrachtet die beiden Arten als Leitfossilien des mitteleuropäischen
Altpleistozäns, die mit jüngeren Faunen nicht näher verbunden sind (LoZek, 1964a).

Die Interglazial-Fauna wurde unter dem Einfluss der Mindel-Vereisung von einer
bedeutend abweichenden Fauna abgelöst. Unseren heutigen Kenntnissen gemäss er-
schienen im Gebiet des ungarischen Mittelgebirges zur selber Zeit zum erstenmal
diejenigen alpinen, alpin-karpatischen und nördlichen Arten, die heutzutage hier nicht
mehr leben oder nur als Relikte vorkommen, dagegen charakteristische Arten der
jüngeren pleistozänen Lössfaunen waren. Folgende Arten können wir als solche er-
wáhnen: Vallonia tenuilabris, Clausilia cruciata, Perforatella bidentata, Trichia strio-
lata. Im Mindel-Interstadial kehrt die Fauna des Günz-Mindel-Interglacials wieder
zurück, aber ohne die erwähnten ausgestorbenen Arten.

Die quantitative Auswertung feinstratigraphischer Methoden an den gesammelten
Probenserien beweist, dass sich inzwischen nicht nur das Faunabild, sonder auch die
Dominanz-Werte der Arten veränderten. Zum Nachweis der kleineren klimatischen
Oszillationen - wo sich die Artzusammensetzung nicht oder wenigstens nicht wesent-
lich ändert - wird die Änderung der Dominanz-Werte angewendet.

Zur Demonstration dieser Methode führe ich diejenigen Diagramme vor, welche
die Änderungen der Dominanz-Werte der wichtigeren Faunenglieder der aus einem
2,5 m mächtigen Kalkschlammkomplex stammenden Probenserie (Fundstelle am Péter-
hegy) zeigen (Abb. 1). Die Dominanzkurven einiger Arten - ihren abweichenden
ökologischen Ansprüchen entsprechend - ändern sich entgegengesetzt, bei anderen Ar-
ten zeigen sie identischen Ablauf, bei wieder anderen sind komplizierte Zusammen-
hänge zu vermerken.

Die erwähnten Beobachtungen, sowie die quantitativen Untersuchungen von M.
Kretzoi an pleistozänen Kleinsäuger-Faunen (Kretzoi, 1956) haben mich dazu veran-
lasst, bei der ökologischen Gruppierung eine andere, von derjenigen meiner Kollegen
abweichende Methode zu verwenden.

Es muss angenommen werden, dass bei den altpleistozänen Arten die Möglichkeit
einer Änderung der ökologischen Anforderungen im Laufe der Zeit nicht ausge-
schlossen werden kann. Zum Beispiel sei hier Pupilla muscorum erwähnt, die
im Günz-Mindel-Interglazial nicht vorkam oder bei einer Dominanz unter 4% blieb,
im kühleren Mindel, aber auf über 13% anstieg. In den Würm-altrigen Löss-Schichten
dagegen ist es gerade umgekehrt: im Fall hoher Dominanz von Arten, die ein feucht-
kaltes Klima beweisen (im Glazial) tritt die Form in kleiner Individuenzahl auf,
steigt aber auch mit der steigenden Dominanz der auf ein milderes Klima verweisenden
Arten (in einem Fall 29,7%, beziehungsweise 59,8%) (Krolopp, 1966). Eine andere Art,
Vertigo pygmaea, meldet sich im Mindel mit kälteindizierenden Formen an, im Würm
aber in milderen Zeitabschnitten.

Ein weiterer Gesichtspunkt ist der, dass die Ökologie einiger heute seltener, im
Pleistozän dagegen häufiger Arten Sehr oft nicht genügend bekannt ist. In einigen
Fällen ist die Frage berechtigt, ob die auf Grund von Schalen oder Schalenresten
identifizierten Schneckenfunde tatsächlich mit den heute lebenden Arten ident sind

114 PROC. THIRD EUROP. MALAC. CONGR.

PUPILLA
Cm SUCCINEA OBLONGA cm АВОА FRUMENTUM cm
250 250 yo rer
200 200 200
450 450 450

400 400 100

50 50 50

0 10 20 30 40%0 40 20 30 40 50% 0 40 20%
VERTIGO VERTIGO

Sn CLAUSILIA PUMILA om VALLONIA ВЫ ANTIVERTIGO ANGUSTIOR
200 200 200 200

450 450 150 150

100 400 400 100

50 50 50 50 /

0 40 20 30 40% 0 10 20 30% 0 10% 0 10%

ABB. 1. Die Anderungen der Dominanz-Werte der wichtigeren Faunenglieder auf dem Profil
am Péterhegy.

KROLOPP 115

oder nicht. Endlich muss gelegentlich mit einem solchen Zusammenspiel der ükologi-
schen Faktoren gerechnet werden, die eine Zusammensetzung der Fauna verursachen,
die in unserem gegebenen Gebiet ja sogar Überhaupt nicht vertreten ist (zum Beispiel
die mitteleuropäischen Lössfaunen).

Deshalb hat der Verfasser bei der ökologischen Gruppierung der Arten die Dominanz-
kurven stets berücksichtigt, beziehungsweise zur Grundlage erhoben. Es muss nämlich
als selbstverständlich angenommen werden, dass Arten, die an Hand vieler Profile
konsequent parallel verlaufende Dominanz-Kurven aufweisen, wohl auch auf äussere
Faktoren auf gleiche Weise antworteten, demnach also auch dieselben oder wenigstens
ähnliche Ökologische Ansprüche stellen. Nachdem aber unter den Umweltfaktoren eben
die Änderungen des Mikroklimas die bedeutendsten sind, welch letztere in Wieder-
spiegelung der Änderungen in der Pflanzendecke auf das Makroklima umgedeutet
werden können, ist den einzelnen Kurventypen eine klimaandeutende Rolle anzuerkennen.
Natürlich ist es kein Zufall, dass wir die Mehrzahl der an Hand parallelen Ablaufes
ihrer Klimakurve als zusammengehörig gefundene Arten auch bis jetzt für solche
gleicher oder wenigstens ähnlicher Okologie halten dürfen. Dabei kann der ókolo-
gische Charakter diesbezüglich mangelhaft bekannter, beziehungsweise nur als fossil
bekannter Arten auf Grund ihrer Dominanz-Kurve in eine entsprechendc Gruppe
eingeteilt und zufolge ihre Ökologischen Eigenschaften ermittelt werden. In bezug auf
die bereits erwähnte Gastrocopta serotina ist soviel schon jetzt festzustellen, dass
sie eine wärmeliebende, trockenheitvertragende Art gewesen sein musste; sie kommt
in grösserer Zahl dort vor, wo dieDominanzxerothermer Elemente auffallend hoch ist
(in einem Beispiel 78%) (Krolopp, 1961).

Auf Grund obiger Überlegungen kann die Landschnecken-Fauna in folgende 6 - durch
Dominanz-Kurve bestätigte - ökologische Typen aufgeteilt werden:

1. Wärmeliebende, trockenheitduldende (xerotherme) Arten (z.B. Abida frumentum,
Truncatellina claustralis, T. cylindrica, Helicella hungarica).

2. Wärmeliebende, feuchtigkeitsbedürftige Arten (z.B. Vertigo moulinsiana, V.
antivertigo, Vallonia enniensis).

3. Feuchtigkeitsbedürftige Arten (z.B. Carychium minimum, Zonitidae, Limacidae).

4. Feuchtigkeitsbedürftige, kälteduldende Arten (z.B. Succinea oblonga, Nesovitrea
hammonis, Perforatella bidentata).

5. Trockenheit- und kälteduldende Arten (z.B. Pupilla muscorum, Р. sterri,
Vallonia tenuilabris, V. costata).

6. Weitere, in keiner obigen Gruppen unterbrachte Arten (z.B. fossile Arten,
Acanthinula aculeata).

Wenn wir die Prozentzahl der einzelnen Gruppen durch Raumdiagramme wieder-
geben, erhalten wir vom obenerwähnten Profil der Fundstelle am Péterhegy folgendes
Bild (Abb. 2).

Es ist klar zu entnehmen, dass in der Mitte und am Ende der Schichtenfolge eine
beträchtliche Klima-Verschlechterung angedeutet ist. An Hand wirbeltierpaläon-
tologischer Beweise vertritt das Profil die Zeitspanne, die aus dem Günz-Mindel-
Interglazial ins Mindel-Glazial tiberftihrte.

Die vorgeführte Methode ist geeignet, die Schichtenfolge, bzw. Einzelschichten an
Hand quantitativ-faunistischer Untersuchungen zu vergleichen, identifizieren und so
auch chronologisch einzustufen. Es ist mir gelungen, die Kalkschlamm-Schichten
der Lokalitäten aus der Umgebung von Budapest folgenderweise zu chronologisieren
(Abb. 3).

Die drei ersten Kolonnen geben Faunen eines Günz-Mindel-Alters wieder.
Die 4. und 5. zeigen Übergangsfaunen, während die 6. und 7. zwei verschiedene
Mindel-Faunen vertreten. Die zwei letzten Kolonnen illustrieren die Fauna der zwei
oberen Schichten des letzten Fundortes, die eine zwischen-Mindel-altrige Klima-

PROC. THIRD EUROP. MALAC. CONGR.

116

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Die Änderungen der Prozentzahl der ökologischen Gruppen im Profil am Péterhegy.

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ABB. 2.

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Eteucn

ABB. 3. Okologisches Bild der Molluskenfaunen in Kalkschlammschichten der Budapester

Lokalitaten.

KROLOPP 117

Verbesserung (wohl das Mindel¡-2 Interstadial), bzw. die darauffolgende Klima-
verschlechterung (Mindel, Glazial?) andeuten. Das geologische Alter dieser Fundstelle
ist auch durch wirbeltierpaliontologische Belege bewiesen (Janossy, 1962).

Aus der Zeitspanne zwischen Mindel-Riss-Interglazial und Riss-Würm-Interglazial
stehen uns sehr wenig Belege zur Verfügung, allein aus dem nördlichen Teil des
ungarischen Mittelgebirges, aus dem Bükk-Gebirge, sind in letzter Zeit einige Faunen
bekannt geworden. Von hier und aus diesem Zeitabschnitt sind folgende für unser
Pleistozän neue Arten zum Vorschein gekommen: Acicula polita, Oxychilus depressus,
Vitrina bielzi, Phenacolimax annularis (Krolopp, 1969).

Das letzte Interglazial (Riss-Würm) ist durch eine für ganz Mitteleuropa bezeichnende
Fauna, die “Banatica-Fauna,” gekennzeichnet. Diese Fauna ist auch von unserem
Gebiet bekannt, mit den Charakterformen Pomatias elegans, Mastus bielzi, Aegopis
verticillus, Soosia diodonta und einer endemischen Süsswasserform, Belgrandia
tataënsis (Krolopp, 1964a). Die wohl schon im Pleistozän ausgeprägte Kontinen-
talität unseres Beckens trägt dafür wahrscheinlich die Schuld, dass eben die namen-
gebende Art der Fauna, Helicigona banatica, allein aus dem nördlichsten Glied des
Mittelgebirges, aus der Riss-Würm-Fauna des Bükk-Gebirges, nachzuweisen war und
zwar in Begleitung anderer, nur hier angetroffener montaner Formen (z.B. Isogno-
mostoma isognomostoma, Perforatella dibothryon) (Krolopp, 1964b).

Aus dem Zeitabschnitt nach dem Riss-Würm-Klimaoptimum und ausdem Frühwürm
kennen wir Faunen mit Ubergangscharakter, in denen die Formen, die ein wärmeres,
niederschlagreicheres Klima beanspruchen (z.B. Carychium minimum, Vertigo anti-
vertigo, Vallonia enniensis, Clausilia pumila) noch vorkommen (Krolopp, 1965).
Diese Formen verschwinden wohl mit dem Kältemaximum des Würm, und erscheinen
erst im Postglazial wieder. In milderen Abschnitten des Würm - wohl wieder dem
mehr kontinentalen Charakter des Karpatenbeckens entsprechend - zeigen xerotherme
Arten das wärmere Klima an (z.B. Abida frumentum, Chondrula tridens, Helicella
hungarica).

Obwohl wir in bezug auf die ungarische Lössfauna über sehr viele alte Angaben
verfügen, sind in letzter Zeit doch einige für das ungarische Pleistozän neue Arten
aus unserem Löss bekannt geworden: Catinella arenaria, Vertigo pseudosubstriata,
Semilimax kotulae.

Feinstratigraphische Schlämm-Aufsammlungen wurden nur in den letzten Jahren
durchgeführt. Für grössere Gebiete gültige Feststellungen konnten aber nur in bezug
auf Süd-Transdanubien getroffen werden. Hier ist der jüngere, würmaltrige Löss
durch zwei Boden-Niveaus dreigeteilt. Für den unteren Löss sind bei einer Succinea
oblonga-Dominanz Formen weiter Ökologischer Valenz bezeichnend (z.B. Pupilla
muscorum, Vallonia costata, Trichia hispida). Die mittleren Löss-Schichten führen
eine Fauna, die wärmeres, trockeneres Klima andeutet (z.B. Pupilla triplicata, Heli-
cella hungarica, Vallonia costata). Succinea oblonga fehlt hier. In oberen Lösslagen ist
wieder Succinea oblonga vorherrschend, neben ihr sind Pupilla sterri, Columella
columella, Vallonia tenuilabris die charakteristischen Formen (Krolopp, 1966).

Aus dem Postglazial stehen uns nur sehr wenig Angaben zur Verfügung. Das stufen-
weise Verschwinden einiger am Ende des Pleistozäns noch häufigen Formen können
wir zwar nachprüfen, wie z.B. bei Valvata pulchella, wohl aber nicht solche Entwick-
lungsphasen der Fauna, die LoZek inder karpatischen Fauna Südslowakiens nachweisen
konnte (LoZek, 1964b). Die Ursache dieser Umstände ist einerseits im Mangel ent-
sprechenden Datenmateriales, anderseits aber in der bereits erwähnten Kontinentalität
des Beckenlandes zu suchen. Eine richtige Montanfauna hat sich im ungarischen Mittel-
gebirge nicht ausgebildet - die holozänen Klimaänderungen haben bloss Dominanz-
schwankungen verursacht.

Endlich sei hier ein Beispiel zur Darstellung der Beziehungen zwischen Faunen-
geschichte und Tiergeographie vorgelegt. Das Nordglied unseres Mittelgebirges,

118 PROC. THIRD EUROP. MALAC. CONGR.

das in seiner Hauptmasse um 800 т hohe Bükk-Gebirge, wird seitens unserer Zoologen
auf Grund der vielen karpatischen Elemente meist zum Karpathicum gerechnet. Meine
Untersuchungen haben nachweisen kónnen, dass das Btikk-Gebirge schon vom Mittleren
Pleistozán an eine eigenartige Mollusken-Fauna führte, die sich derjenigen der Karpaten
anschloss, wonach eben die paläontologische Dokumentation die Berechtigung obiger
Annahme gut unterstützen - ja beweisen - konnte.

LITERATUR

BARTHA, F., 1954, Die pliozäne Molluskenfauna von Ocs. M. All. Földt. Int. Évk.,
42(3): 167-205.

BARTHA, F., 1955, Untersuchungen zur Biostratigraphie der pliozánen Mollusken-
fauna von Várpalota. М. All. Földt. Int. Evk., 43(2): 275-359.

JANOSSY, D., 1962, Der erste Nachweis von Hippopotamus antiquus Desmarest, 1822
im ungarischen Altpleistozán (Budapest). Allattani Közl., 49(1-4): 63-74.

KRETZOI, M., 1956, Die altpleistozänen Wirbeltierfaunen des Villanyer Gebirges.
Geologica Hung. Ser. Pal., 27: 125-256.

KROLOPP, E., 1961, Die zoogeographische und ökologische Untersuchung der Mollus-
kenfauna des altpleistozánen Kalkschlammes der Umgebung von Buda. (Disser-
tation). p 1-141. (Maschinenschrift, ungarisch).

KROLOPP, E., 1964a, Die Molluskenfauna. т: Vertes, etc.: Tata, eine mittel-
paláolitische Travertin-Siedlung in Ungarn. Arch. Hung., 43: 87-103.

KROLOPP, E., 1964b, Das erste pleistozine Vorkommen von Helicigona banatica Rm.
(Gastropoda) in Ungarn und dessen zoogeographische Bedeutung. Ann. Hist. -Nat.
Mus. Nat. Hung., 56: 185-188.

KROLOPP, E., 1965, Biostratigraphische Untersuchung der Pleistozánbildungen des
Dorog-Esztergomer Beckens. М. All. Földt. Int. Evi Jel. 1963 &vröl, р 133-147.

KROLOPP, E., 1966, Biostratigraphische Untersuchung der Lössbildungen in der
Umgebung des Mecsekgebirges. М. All. Földt. Int. Evi Jel. 1964 &vröl, р 173-191.

KROLOPP, E., 1969, Die Molluskenfauna der Felsnische bei Uppony. Eiszeitalt. u.
Gegenw., 19: 37-41.

LOZEK, V., 1964a, Neue Mollusken aus dem Altpleistozán Mitteleuropas. Arch.
Molluskenk. 93(5-6).

LOZEK, V., 1964b, Quartärmollusken der Tschechoslowakei. Rozp. U.u.g., 31: 1-374.

ROTARIDES, M., 1931, Die Schneckenfauna des ungarischen Lösses und die ungarische
rezente Schneckenfauna, mit besonderer Berücksichtigung der Lösse von Szeged.
A Szegedi Alföldkut. Biz. Könyvt. 6(A/8): 1-180.

ROTARIDES, M., 1936, Untersuchungen über die Molluskenfauna der ungarischen
Lössablagerungen. Festschr. Embrik Strand, 2: 1-52.

SOÖS, L., 1926, The Past of the Hungarian Mollusc Fauna. Ann. Mus. Nat. Hung.,
24: 392-421.

AUSZUG

Infolge ihrer guten Fossilisationsfähigkeit und der im allgemeinen massenhaften
und ziemlich gleichmässigen Verbreitung in den geologischen Formationen kommt den
Mollusken bei den faunengeschichtlichen Untersuchungen eine sehr wichtige Rolle zu.

Die Angaben über Entfaltung der bereits lebenden Molluskenfauna des Karpaten-
beckens sind 1926 durch L. Soös zusammengefasst worden. Seit dieser Zeit sind sehr
viele paläontologische Daten zusammengebracht worden, die einerseits das Erscheinen
einiger Gattungen bzw. Arten klären oder in ein anderes Licht setzen, anderseits
aber über die Molluskenfauna mehrerer geologischer Zeitabschnitte ein besseres

KROLOPP 119

Gesamtbild abgeben. Die nach Einführung der Schlämm-Methode durchgeführten
Massenuntersuchungen ergaben vor allem eine Vermehrung der kleinen Formen. So
wuchs besonders die Zahl derjenigen Arten an, die bereits im Pliozän dem Karpaten-
becken angehört haben. Dabei sind 32 (etwa 20%) der um 170 Arten zählenden pleisto-
zänen Molluskenfauna des Karpatenbeckens im Laufe der letzten 25 Jahre bekannt
geworden.

An Hand der Bearbeitung der quantitativen Verhältnisse der fossilen Faunen gelang
es nicht nur in bezug auf das Faunenbild der einzelnen Abschnitte des Pleistozäns,
sondern auch über das zahlenmässige Verhältnis der einzelnen Arten zueinander
grundlegende Angaben zu gewinnen. Eine Änderung in diesen Verhältniszahlen gibt
uns eine neue Möglichkeit biostratigraphischer Feingliederung.

и
= ee
N
Ил, учи aie *
=a 4900

eet pr la LN Mr ENT ER LA e
TINE ead ¿A HOS ee FAA A e

MALACOLOGIA, 1969, 9(1): 121-125
PROC. THIRD EUROP. MALAC. CONGR.

SUBSTRATE RELATIONS IN SOME PISIDIUM SPECIES
(EULAMELLIBRANCHIATA: SPHAERIIDAE)!

C. Meier-Brook2

Limnologisches Institut der Universität Freiburg 1. Br.
(Walter-Schlienz-Institut), Falkau, Schwarzwald, W. Germany

The species of the sphaeriid genus Pisidium are mostly mud dwelling clams living
in freshwaters in all parts of the world. In temperate zones, waters are generally
inhabited by several species of the genus. For example, in Lake Titisee in High Black
Forest (Germany), one sample taken with an Ekman-Birge-grab may consist of up to
7 Pisidium species. This joint occurrence is in contrast to our experiences on snail
genera, and it seems to be not in accordance with “Gause’s principle.” A view upon
the different surfaces of the shells, however, appear to reflect differences in ecologi-
cal enníchement. A dense growth of blue-green algae commonly occurring on the
shells of Pisidium hibernicum Wstl. in Lake Titisee led me to study the more abun-
dant species of that lake with regard to their substrate relations.

Certain grain size preferences which mean horizontal substrate relations could
be found in the following experiments. Two fractions of muddy original Titisee sedi-
ment, free of minerals, one of whichhaving grain sizes of more than 0.8 mm, the other
of less than 0.5 mm, were put side by side in a Petri dish as shown in Fig. 1. The
layer was about 1 cm thick and was covered with lake water. In each experiment 50
to 86 (average 60) individuals of 3 species were alternately arranged on the limit be-
tween the 2 fractions. Ten experiments using day light and exposure times of 75
hours on the average yielded grain size preferences as follows (Fig. 2). Pisidium
lilljeborgii Cl. clearly preferred (67 + 14%) the fine-grained fraction, whereas P.
hibernicum (40 + 15%) and, particularly, P. nitidum Jen. (31 + 13%) tended to avoid it
and to migrate into the coarse sediment. The interspecific differences in behaviour
were statistically significant on the 0.1%-level (Chi-square method). These findings
are in agreement with own observations on the distribution of the 3 species in Lake
Titisee. Down to a depth of 2m the bottom is formed by gravel, here and there having
troughs which are filled up with fine detritus. From 2 to 4 m there is a zone of dense
vegetation formed by Isoetes lacustris, Litorella uniflora, Myriophyllum sp., and
Nitella sp. This belt is catching coarse materials such as leaves, small branches,
pine cones, wood debris, etc. Below it the sediment again consists of fine mud. In
the coarse sediment of the Jsoetes-zone, P. hibernicum constitutes the by far greatest
part of the Pisidium-fauna, whilst in the fine grained sediment both above and below
this vegetation zone, P. lilljeborgii is the predominant species. P. nitidum has its
greatest abundance in the /soetes-zone too; belowit, however, its abundance so rapidly
decreases that I believe it is on other than substrate reasons.

Besides the horizontal substrate relations, there was some evidence of vertical
substrate relations. As was obvious from the green colour of Pisidium hibernicum,
this species must exert an at least temporary epipelic mode of life, otherwise photo-
synthesis of the blue-green algae would not be guaranteed. In the laboratory, too,
Р. hibernicum would prefer to creep upon the mud surface rather more than other

Supported by Deutsche Forschungsgemeinschaft.

“Present address: Tropenmedizinisches Institut d. Univ. Tübingen, D-74 Tubingen, W. Germany.

(121)

122

PROC. THIRD EUROP. MALAC. CONGR.

FIG. 1. Petri dish used for substrate choice experiments. The arrow indicates that light fell
in the direction of the limit between the sediment fractions. For further details see text.

A
70}
60
50!
40!
30

< 0.5mm

Ory
oe

nn. .........
e. o. o. e...

FIG. 2. Horizontal substrate relations in Pisidium lilljeborgii, P. nitidum, and P. hiberni-
cum from Lake Titisee. The figure shows the percentages of individuals preferring sediment
fractions of different grain sizes after experiments in Petri dishes as shown in Fig. 1.

MEIER-BROOK 123

species do. Bright sunshine, of course, induced even P. hibernicum to burrow totally
into the sediment. The differences in behaviour between P. hibernicum and the other
pisidia could merely be due to gradual differencesin phototactic or light induced posi-
tive geotactic reaction. A series of 10 experiments showed that this at least cannot be
the only explanation.

A mixed community of specimens of 3 or 4 species was put on mud in Petri dishes
and covered with a second mud layer approximately 1 cm in height. One dish was
exposed to diffuse daylight, while the other one was kept in total darkness just beside
it. Every midday and evening at the following days, all individuals visible from the
surface were collected and identified. After each reading the animals were put back
below the sediment surface. In the first 6 experiments a total of 134 individuals of
Pisidium lilljeborgii, P. nitidum and P. hibernicum were used. The other 4 experi-
ments were done with 160 individuals of 4 species including the profundal species,
Р. conventus Cl. The percentages of animals which have left the interior of the sedi-
ment at the reading times are given in Fig. 3, which combines the results of both
series of experiments. As expected, the proportion of individuals exhibiting an epi-
pelic mode of life was much greater in darkness than in light. Nevertheless, the
differences between P. hibernicum and the other species examined were still existent,
being statistically significant on the 0.1%- resp. on the 1%-level in the 2 series. The
cause of the interspecific differences is not yet known; the only statement which can
be derived from the light experiments and from occasional observations is that P.
hibernicum is induced to enter below the sediment surface at higher light intensities
than the other species.

Summarizing the results referred to above, the substrate relations of the 3 species
common in the litoral zone of Lake Titisee can be described as follows: Pisidium
lilljeborgii prefers an endopelic mode of life in fine grained organic sediment. P.
nitidum is strongly restricted to biotopes below the sediment surface, too, but prefers
coarse organic sediment with large-pored interstitial spaces which enable the animal
to provide itself with water sufficiently rich in oxygen. P. hibernicum frequently
would creep on the sediment surface, preferring coarse organic substrate which pre-
vents the animals from Sinking in.

It has to be regarded that the behaviour patterns demonstrated here are not neces-
sarily representative of all species named. But at least Pisidium hibernicum seems
to prefer an epipelic mode of life elsewhere, too, as the shells may bear green or
blue-green algae also in other lakes.

Finally, I may be allowed to present some details of the endopelic mode of life,
which appeared to be principally similar in the 4 species m.a. Fig. 4 is summing up
the findings of a lot of cuvette observations which were confirmed by flashlight photo-
graphs of dark experiments. In the beginning of a burrowing act the clam bores itself
steeply into the sediment, the angle between sediment surface and boring hole being
about 70°. Some mm below the surface the clam abruptly changes its digging direction
and forms a canal several mm in length and approaching a line parallel to the sur-
face (bc in Fig. 4). Then the animal takes in a resting position with its beaks kept
down. The pedal aperture, which hence lies upwards, is opened and the anal siphon is
stretched out in direction of the burrowing canal. The way taken by the nutrient and
respiration water remained obscure until a suspension of carmine grains was used.
Soon after the carmine had been added, the sediment particles in a funnel-like region
above the foot slit (marked by arrows in Fig. 4) carried red caps demonstrating that
the water takes its way through the interstitial pores of the sediment.

The ingestion of the water exclusively takes place through the pedal aperture, like
in Erycinacean bivalves (Ponder, 1967). The branchial opening is either absent, as in
Pisidium conventus and other neotenic pisidia, or kept closed, as in all European

124 PROC. THIRD EUROP. MALAC. CONGR.

Pconv: P.hib.
(n=60) (n=260)

EXEPUENTERER

FIG. 3. Vertical substrate relations in Pisidium lilljeborgii, P. nitidum, P. conventus, and
P. hibernicum from Lake Titisee. The percentages of individuals migrating to the sediment
surface in light (above) and dark experiments (below) are indicated. Before each experiment the
animals were exposed below the sediment surface.

.......)..

..
vo. ee 00.

...

ee + + + @

oee eee + + + @
ee + + +

. . e.
.

.
.
oe

. ..o o... + + + .
eee +... 0e + + + + +
0 0 + + + + + + + + ©

eee

FIG. 4. Endopelic position ofa Pisidium animal after cuvette studies on Pisidium lilljeborgü,
P. nitidum, Р. conventus, and P. hibernicum from Lake Titisee. Key to lettering: bc, burrow-
ing canal; f, accumulation of feces; р, Pisidium animal; s, sediment; w, water.

MEIER-BROOK 125

species of the subgenus Rivulina which I could examine till now.

The assertion can often be found in literature that in P2sidium the water is ingested
through the branchial opening. In my opinion, this error is due either to a conclusion
from analogy from the related genus Sphaerium, or to the fact that the branchial open-
ing is indeed opened in disordered (e.g., by a relaxing agent) or in dead animals. A
branchial aperture which is kept open, however, really serves as an ingestion opening
besides the foot slit in living clams.

The water and the feces leaving the clam through the anal siphon are pressed into
the burrowing canal where the feces (f) are accumulated in a considerable distance
from the animal. As far as is known to me, no investigator of endopelic animals has
till now come across a mode of life like that in Pisidium, which is completely lacking
a boring hole for the ingestion of water. Only Pratt & Campbell (1956) reported on
observations on Venus mercenaria, which sometimes is unable to keep its burrowing
aperture open and thus is forced to inhale water through the pores of the sediment.

REFERENCES

PONDER, W. F., 1967, Observations on the living animal and mode of life of some
New Zealand Erycinacean bivalves. Trans. Roy. Soc. New Zealand, Zoology,
10(3): 21-32.

PRATT, D. M. & CAMPBELL, D. A., 1956, Environmental factors affecting growth
in Venus mercenaria. Limnol. Oceanogr., 1: 2-17.

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MALACOLOGIA, 1969, 9(1): 127-134
PROC. THIRD EUROP. MALAC. CONGR.

PROBLEMS OF LYMNAEA TRUNCATULA ECOLOGY
IN INVESTIGATIONS OF FASCIOLIASIS

М. J. Morphy, J. а. Ross and В. M. Taylor

Veterinary Research Laboratories,
Stormont, Belfast, U. K.

Fasciola hepatica is a parasite responsible for serious disease problems in sheep
and cattle in many parts of the world. Itis of particular importance in Ireland. Esti-
mates of economic loss due to this disease in Northern Ireland suggest that it may
amount to over £3,000,000 per year. Investigations have been undertaken at the Veter-
inary Research Laboratories at Stormont, Belfast, over the past 6 years, and studies
have been made into the effects of infection in sheep, cattle and pigs (Annual Report,
1967). Initially, studies concentrated on the clinical pathology and immunology of the
disease in sheep and cattle, but during the past 2-3 years more attention has been
paid to the epidemiology, and to the inter-relationship between climatic conditions
and infection levels in farm livestock. Predictions of the incidence of fascioliasis
have been made over several years using climatic data, and on these predictions,
warnings have been used to alert farmers to initiate prophylactic measures. Studies
have followed the build up of metacercariae on pasture and consequent infections in
tracer animals (Ross, 1967a, 1967b, 1968). These studies linked with abattoir sur-
veys of infection (Ross, 1966), preliminary studies of snail habitats and increase in
Snail populations, have produced a picture of the epidemiology and seasonal trends of
the disease (Ross & O’Hagan, 1968). During these studies it became clear that much
of the data required to relate infections in livestock to numerical variations in snail
populations and their infection levels were not present, and that techniques and litera-
ture required to obtain this information were not available. Further studies have now
been initiated to investigate the epidemiology of Fasciola hepatica infections in sheep
and cattle, and to correlate the findings with detailed studies on the ecology of Lymnaea
truncatula. A team has been formed and is now working on the problem at this
laboratory.

The incidence of fascioliasis in Northern Ireland is particularly high and in some
areas, especially in the western region, where thereis a high rainfall, a 50% mortality
occurs in sheep, if dosing with anthelmintics is not practiced at 3-week intervals. In
eastern areas where the annual rainfall is lower, the incidence is not quite so high, and
less frequent dosing is often employed with success. The overall incidence of fascio-
liasis has been estimated from abattoir surveys performed over a number of years
by Gracey (1959). Data from this survey are presented in Table 1. The number of
cattle slaughtered at different abattoirs in Northern Ireland is shown, and the per-
centage of these in which, because of heavy fluke infection, the liver was unfit for
human consumption and therefore condemned. It should be emphasised that these
figures must not be confused with incidence of clinical cases of the disease. A survey
of this kind can at best give only an indication of the geographical incidence of fascio-
liasis. As most of the cattle may have experienced at least 2 fluke seasons and may
have been sold on more than one occasion prior to being brought for slaughter, the
data cannot indicate details of the year or source of infection. Despite inadequacies,
these statistics can provide a useful picture ofthe distribution and incidence of disease,
when figures from abattoir surveys are plotted on a rainfall map of the Province
(Fig. 1). There is apparently a fairly good correlation between areas with a high

(127)

128 PROC. THIRD EUROP. MALAC. CONGR.

incidence of disease and areas of high rainfall, a relationship which has been estab-
lished in England by Ollerenshaw (1966). The average incidence of heavy infections
in cattle is around 67% in Northern Ireland, and in problem areas is over 90%. More
particular surveys have shown that the absolute incidence of infection in both sheep
and cattle is between 95 and 100%.

More detailed abattoir surveys have also provided data on the seasonal incidence
of fascioliasis. Fig. 2 shows the results of a survey carried out at Belfast Abattoir
during the 1964/65 season (Ross, 1966). The immature flukes show a peak infection
in the liver during the September-November period. In the spring, lower infections
are observed either due to winter carry-over of metacercariae on the pasture, or
to retardation of immature flukes in secondary infections (Ross, 1967c). The mature
flukes show a peak that follows that of the immatures after a delay of about 2 months.
This is the period spent by the immature flukes wandering through the liver, and at
the end of this time they migrate to the bile duct and reach maturity. Comparing the
levels of immatures in October 1965 and October 1964, the higher level in the former
year may have been partly due to a greater incidence of the disease in Northern
Ireland.

In Fig. 3, which shows the average monthly temperatures for Northern Ireland
(Meteorological Office, 1968), a horizontal line has been positioned at 10° C and it can
be seen that temperatures above this, at which maturation of fluke eggs and propaga-
tion of Lymnaea truncatula proceed, are present in Northern Ireland only from mid-May
to mid-October. The build up of sufficient numbers of snails to support and produce a
Significant infection on the pasture, must therefore occur within these months. A
water surplus giving rise to waterlogged conditions favours development of both the
snail and the fluke eggs. It has been shown by Ollerenshaw & Rowlands (1959) that
measurement of variations in the amount and distribution of rainfall and in tran-
spiration during these months, offers a method of estimating the possible build up of
snail populations and their infection levels and the resultant levels of infection in live-
stock. These factors have been used to produce the formula which gives the value
known as the Meteorological Value (Mt.) for each month from May-October, indicating
the degree of wetness of habitats. Summationof meteorological values for each month
from May-October provides an estimate for the incidence of infection within any year.
Table 2 presents meteorological values for Northern Ireland for the past 4 years and
for one year, 1958, in which a disastrous fluke infection occurred. The predicted
incidence, based on meteorological values for each year, is also shown. The values
and predictions are compared with actual incidence, based on figures obtained from
post-mortem material and from epidemiological studies carried out during these
years. The correlation between observed and calculated incidence of disease is seen
to be fairly good, except for one year, 1967, when an over-estimate of incidence
occurred. It is suggested that the lower incidence in that year was due to an abnor-
mally dry June. From thisitisclear that while this method of estimating snail propa-
gation is useful, it needs modification, and that more detailed studies of the dynamics
of snail populations in relation to variationsin climatic conditions are required.

Earlier epidemiological studies at the Veterinary Research Laboratories, Belfast,
have related climatic conditions, snail density, incidence of infection in snails and the
pattern of metacercariae infection on the pasture, to infections in sheep and cattle,
and have compared these over a number of years (Ross, 1967a, 1967b, 1968). Fig. 4
shows some of the results of studies carriedout on a site in the east of Ulster. It can
be seen that there is a peak in the percentage of infected snails during the period
June-October, for the 1966/67 season. This peak is followed by a rapid decline in the
percentage of infected snails, coincident with the period during which the mature
cercariae emerge from the snail and pass on to the grass, where they encyst to form

MORPHY, ROSS and TAYLOR 129

0-40
40-50
50-60
> 60
INCHES

FIG. 1. Map of Northern Ireland, showing percentage condemnation rates of bovine livers to-
gether with details of the distribution and annual average amount of rainfall, (Met. Office, 1967,
1968).

2 à

average number of flukes per liver
h
©

№

1964 1965

FIG. 2. Seasonal incidence of fascioliasis in Northern Ireland.

130 PROC. THIRD EUROP. MALAC. CONGR.

rainfall

temperature

N
x maximum
mean

‘No minimum

JP IM Ae МСУ eee ES FOREN BD
monthly averages

FIG. 3. Monthly average temperature and rainfall for Aldergrove Met. Station, (Met. Office,
1967, 1968).

metacercariae. This is indicated in the lower graph in Fig. 4. A spectacular peak
in metacercariae infection during October, is followed by a decrease during the early
part of the winter, with little carry-over of infection on the pasture over the winter
period. The percentage of infected snails for the 1964/65 season, is also shown, and
it is suggested that the very low incidence of infection during the July-September period
was probably an anomaly arising from problems involved in sampling. However, this
data has been included, as it demonstrates - together with that for the 1966/67 season
and field observations over a number of years - that carry-over of infection in the
Snail does not appear to be of significance in Northern Ireland. This leads us to
suggest that any late infection of livestock, during the spring and early summer, is
more likely to be due to carry-over of metacercariae infection on the pasture, rather
than to carry-over of infection in the snail. A carry-over infection in the snail has
been suggested in England by Ollerenshaw & Rowlands (1959). It is clear that further

MORPHY, ROSS and TAYLOR 131

TABLE 1. Incidence of bovine fascioliasis in Northern Ireland
Abattoir i. Total bovine kill Berseninee of animals
affected with fascioliasis
Enniskillen 2,724 94.3
Londonderry 8,326 9159
Larne 3,770 76.1
Downpatrick 2,163 74.8
Lurgan 8,288 40.6
Newtownards | 2,930 | 27.4

TABLE 2. Comparison of meteorological predictions and actual incidence of disease, for the
east of the Province

Aggregate of monthly Predicted incidence Actual incidence

Year BE FREE
“МЕ. ” values of fascioliasis of fascioliasis

1958 | 500 Disastrous Disastrous
1964 412 Average Average
1965 453 Above average Above average
1966 431 Average Average
1967 ch 429 e Average Below average

TABLE 3. Survey of snail populations on fluke sites, following outbreaks of fascioliasis

County Date of disease | Type of | Date of en Snails рег Percentage of | Site size

of site outbreak disease sampling lb. of soil) snails infected
Armagh Oct. Acute | Nov. 136 | 50 | Extensive
Down Nov. Acute Nov. 52 | 25 Extensive
Antrim Oct. Subacute Oct. 6.7 75 Extensive
Down Sept. Subacute Sept. 1579 100 Moderate
Down Nov. Chronic Oct. 0.6 10 Moderate
Fermanagh Jan. Chronic Oct: 23 10 Small
Antrim Dec. Chronic ip Sept. eke 2.5 30 Moderate

132 PROC. THIRD EUROP. MALAC. CONGR.

LYMNAEA TRUNCATULA

°lo age of infected snails

METACERCARIAE

600

metacercariae / lb. pasture

months

1966-1967) == 1964—1965

FIG. 4. Fluctuations in levels of snail and pasture infection.

studies are required to determine the nature, extent and importance of carry-over
infection in and between different regions.

More recent investigations (Ross & O’Hagan, 1968) with sheep on a site in the east of
the Province, suggest that there is a minimum level of snail population and percentage
of snails infected, necessary to produce a significant disease, but this relationship does
not appear to be a simple one. Table 3 indicates that acute outbreaks of fascioliasis
occurred from October to November on extensive sites, where there were high den-
sities of snails of which a considerable percentage were infected. Sub-acute outbreaks
occurred during September and October on moderate to extensive sites, having lower
densities of snails, but a higher incidence of infection within the populations. Chronic
cases of the disease occurred later in the winter from November-January, on small
to moderate sites, where there were very low densities of snails, of which only a
small percentage were infected.

Whilst these studies have enlarged our knowledge of fascioliasis, there are still

MORPHY, ROSS and TAYLOR 133

many factors in the ecology of the snail which are unknown and require investigation.
Of the problems needing attention, one of the most important is the need for design
of techniques and methods which will allow accurate assessment of the dynamics and
density of snail populations and the distribution of animals within their habitat.
This is particularly relevant with the advent of renewed interest in control of fluke
disease by application of molluscicides. The snail Lymnaea truncatula has a great
reproductive potential; Kendall (1953) has found that under optimum conditions in the
laboratory, snails may reach maturity in 21 days, and that an individual snail is capable
of giving rise to 25,000 in 12 weeks. Field observations on the rate of popula-
tion increase under natural conditions suggest an 8-10 fold seasonal increase, which
is perhaps more realistic (Sosipatrov & Shumakovich, 1966). Partial destruction of
snail populations by molluscicides may be a feasible control measure, but until
ecological studies have established such details as rates of population increase and
repopulation, molluscicidal control schemes will remain uncertain in their efficiency.
Any form of molluscicidal control must aim either at complete annihilation of popu-
lations on specific sites or decimation of populations of infected snails prior to the
emergence of cercariae. An accurate site assessment is extremely important, as ob-
servations suggest that a residual population of snails left on the pasture after mol-
luscicidal treatment can effect a rapid recovery resulting in an increase of the popu-
lation towards its former high level.

Visual count methods, either for a standard period of time or over a unit area of
habitat, are not sufficiently accurate either as a basis for ecological study or when
attempting to assess the extent of a flukey site prior to implementing some form of
control. These subjective methods are at a considerable disadvantage in that they
depend to a very large extent on the visual acuity and diligence of the searcher, and
furthermore they suffer from being biased. When one considers that a newly hatched
snail is little more than 1/2 mm inheight, the limitations of such methods are obviously
apparent. Work at present in progress at Belfast suggests that snails are frequently
found in moist areas of pasture where thereis а thick green sward and these areas are
often not suspected of harbouring the snail, and yet it has been found to be present in
substantial numbers. Conversely, it is not uncommon for the experienced worker to
find that searches for snails on sites, which had previously shown large concentra-
tions of snails, often prove fruitless when examined after an interval of only a week
or so. In these circumstances then, the visual searching method is not to be
recommended.

A rigorous sampling technique isan absolute essential, in that it will be instrumental
in providing some of the basic ecological data required firstly, as a basis for develop-
ing systems of forecasting and disease control, and secondly, in implementing such
control measures, whether they involve anthelmintic treatment, molluscicidal applica-
tion or pasture management. At the present state of our knowledge, it would appear
that a combination of these methods is required in most circumstances and that future
selection of the most effective method or combination of methods, will be dependent
to a very large extent on the conditions prevailing in the problem area, of which
details of the snail populations will perhaps be cardinal.

Information on the dynamics of snail populations, mortalities over winter periods,
and reproductive potential of different sized populations at the beginning of the breed-
ing season are just some of the required details, which would be of great use to the
pesticide expert as he would be in a more informed position to give advice as to when
in the year treatment should be applied. Information on the influences of different
environmental factors such as climate, different kinds of pasture management,
water conditions, to mention but a few, on the behaviour of the snails and their dis-
tribution and population dynamics, will provide some of the basic knowledge required

134 PROC. THIRD EUROP. MALAC. CONGR.

for designing molluscicidal control programmes and in formulating more effective
systems of disease forecasting.

The requisite basic techniques to provide much of this information are now estab-
lished at the Stormont laboratory, and investigations are proceeding which - in con-
junction with epidemiological studies of the disease in farm animals - should answer
many of these important questions. A vast quantity of data on individual facets of
fascioliasis has been collectedinthe past, buthas suffered from lack of complementary
studies on snail populations. The recent renewed interest in molluscicidal control
has, however, highlighted this deficiency, and it is hoped that it will stimulate more
detailed investigations of this disease complex.

REFERENCES

GRACEY, J. F., 1959, A study of disease incidence and wastage in livestock in Northern
Ireland. Ph.D. Thesis, Queen’s University, Belfast.

KENDALL, S. B., 1953, The life history of Lymnaea truncatula under laboratory
conditions. J. Helminth., 27: 17-28.

Meteorological Office, Belfast, 1967, Monthly and annual averages of rainfall for
Northern Ireland; WMO period 1931-1960. Hydrological memorandum, No. 35.

Meteorological Office, Belfast, 1968, Averages of air temperature, 1931-1960.
Memorandum,

OLLERENSHAW, С. B., 1966, The approach to forecasting the incidence of fascio-
liasis over England and Wales 1958-1962. Agr. Meteorol., 3: 35-53.

OLLERENSHAW, C. B. & ROWLANDS, W. T., 1959, A method of forecasting the
incidence of fascioliasis in Anglesey. Vet. Rec., 71: 591-598.

ROSS, J. G., 1966, An abattoir survey of cattle liver infections with Fasciola hepatica.
Brit. Vet. J., 122: 489-494.

ROSS, J. G., 1967a, An epidemiological study of fascioliasis in sheep. Vet. Rec.,
80: 214-217.

ROSS, J. G., 1967b, A further season of epidemiological studies of Fasciola hepatica
infections in sheep. Vet. Rec., 80: 368-371.

ROSS, J. G., 1967c, Experimental infections of cattle with Fasciola hepatica: high
level single infections in calves. J. Helminth., 41: 217-222.

ROSS, J. G., 1968, Epidemiological studies of fascioliasis. Vet. Rec., 81: 695-699.

ROSS, J. G. & O’HAGAN, J., 1968, Lymnaea truncatula population studies: the use
of a soil sampling technique in studiesoffascioliasis. Brit. Vet. J., 124: 266-269.

SOSIPATROV, G. V. & SHUMAKOVICH, E. E., 1966, [Population dynamics and den-
sity of the mollusc Galba truncatula and its infestation with larvae of Fasciola
hepatica in Moscow province conditions.] Mater. konf. obshch. hel’mint., 1:
253-256.

VAN DEN BRUEL, W. E. & MOENS, R., 1964, Des possibilites d’utilisation de la
cyanamide calcique pour la lutte contre la distomatose bovine par la destruction
de Limnaea truncatula Müller, hote intermediaire de Fasciola hepatica L.
Parasitica, 20(2): 41-70.

Veterinary Research Laboratories, 1967, Annual report on research and technical
work. Ministry of Agriculture, Northern Ireland. p 95-109.

MALACOLOGIA, 1969, 9(1): 135-141

PROC. THIRD EUROP. MALAC. CONGR.

PROBLEME DER MASSENVERMEHRUNG VON
HELIX POMATIA L. (WEINBERGSCHNECKEN)

Oskar Nawratil
Zool. Institut а. Universität Wien, Austria
EINLEITUNG

Pressemeldungen zufolge beträgt der jährliche Bedarf Frankreichs - wo die Wein-
bergschnecke seit altersher ein Volksnahrungsmittel ist - 90.000 Tonnen. Während in
Frankreich selbst die Weinbergschnecke so gut wie ausgestorbenist, kann das Sammeln
von Wildschnecken in den klassischen Weinbergschneckenländern: Deutschland,
Österreich, Polen, Tschechoslowakei, Teile Jugoslawiens, Italiens und der Schweiz,
nur einen Teil dieser benötigten Menge erbringen. Frankreich ist deshalb auf den
Import von qualitativ nicht gleichwertigen Schnecken wie z.B. Helix aspersa, Helix
rumelica, aus Ostländern angewiesen. Importeure und Konservenerzeuger in Frank-
reich betonen immer wieder, dass sie die echte Weinbergschnecke aus mehrfachen
Gründen vorziehen und einige Fabrikanten sind bereits dazu übergegangen, ihre Ware
auf der Etikette durch den Aufdruck “Helix pomatia” zu kennzeichnen, was in diesem
Fall als Gütesymbol zu werten ist.

Zu dieser bereits jetzt grossen Menge für Speisezwecke benötigter Schnecken wird
in naher Zukunft ein Bedarf der pharmazeutischen Industrie dazukommen; dies ist
aufgrund der laufenden Forschungen unbedingt zu erwarten. Es seien in diesem
Zusammenhang bloss die bereits erzielten Erfolge bei der Pertussisbehandlung mit
einem Präparat erwähnt, dessen wirksame Substanz auf einem Sekret der Helix
pomatia beruht (Pantlen, 1953; Mainil, 1950; Quevauviller, et al., 1953), ferner sei der
Arbeiten Prokop’s und Mitarbeiter gedacht, nach welchen die Bestimmung menschlicher
Blutgruppen mit dem Anti-Ayp und die Feststellung von Aszitestumorzellen möglich
ist (Prokop et. al., 1965; Rackwitz et al., 1965; Kim et al., 1966; Dietz, 1966; Uhlen-
bruck & Prokop, 1966; Uhlenbruck et al., 1966; Prokop, 1967; Prokop et al., 1967;
Prokop et al., 1968) und schliesslich könnte die Weinbergschnecke in der Behandlung
des Diabetes mellitus (Präparat “Diabetex” von Dr. A. Roswadowski in Tailfingen,
W. Germany) oder zumindest für die Diät eine Bedeutung erlangen.

Zu einer weiteren Bedarfserhöhung führte letztlich der Umstand, dass in den mittel-
europäischen Ländern das Schneckenessen aus der Vergessenheit wieder in die Mode
rückte; Österreich blieb davon nicht ausgenommen.

Diesem enormen Bedarf, der nicht einmal mehr annäherungsweise gedeckt werden
kann und in der Zukunft eine weitere Erhöhung erfahren wird, steht auf der anderen
Seite der Rückgang des Naturvorkommens in den klassischen Weinbergschnecken-
ländern gegenüber: durch die Methoden der modernen Landwirtschaft gelangen
chemische Dünge- und Pflanzenschutzmittel immer mehr in die Randgebiete der eigent-
lichen Anbauzonen, Wegränder, Bachufer, Windschutzstreifen etc., und damit in den
Lebensbereich der Weinbergschnecken. Aus den Weingärten ist die “Weinberg”-
schnecke dieserart längst vollständig verschwunden. Zieht man wirtschaftliche Aspekte
in Erwägung, so ergibt sich die Notwendigkeit, die Weinbergschnecken in Zucht-
kulturen zu vermehren, eigentlich von selbst. Der jährliche Deviseneingang für
Österreich betrug allein aus dem Export der gesammelten Wildschnecken an die
drei Millionen Schilling, wobei diese Summe nur die vorhandene Menge Schnecken,
nicht aber die Nachfrage limitierte; zweifelsohne hätte eine weit grössere Menge ohne

(135)

136 PROC. THIRD EUROP. MALAC. CONGR.

Schwierigkeiten abgesetzt werden Кбппеп. Es steht somit fest, dass die Weinberg-
schnecke ein Faktor ist, dessen volkswirtschaftliche Bedeutung nicht tibersehen werden
darf. Darüber hinaus könnte die Züchtung von Weinbergschnecken vielen Kleinland-
wirten, Gebirgsbauern, Rentnern etc., eine Nebeneinnahme erbringen, die eine echte
Krisenfestigung darstellen würde.

ZÜCHTUNG

Obwohl die Weinbergschnecke in jedem Anfängerpraktikum der meisten Universi-
täten seziert wird, ist über ihre Biologie und Populationsdynamik beinahe nichts
bekannt. Die genaue Kenntnis gerade dieser ist aber unbedingt notwendige Voraus-
setzung, wenn ein Naturgesetz durchbrochen werden soll; dies ist immer der Fall,
wenn Massenvermehrung einer bestimmten Art angestrebt wird.

Da eine Weinbergschnecke im Laufe ihres Lebens mehr als zweihundert Eier ablegen
kann, kommt es in der Natur immer wieder zu Massensterben von Jungtieren und auch
adulten Tieren, da schliesslich, soll die Bestandesdichte der Art erhalten bleiben,
nur aus einem einzigen Ei eine geschlechtsreife Schnecke werden darf. Zu ähnlichen
Massensterben ist es früher oftmals auch in den “Schneckengärten” gekommen und
auch heute noch können solche Vorkommnisse nicht völlig ausgeschlossen werden.

1. Historischer Überblick

Die erste Notiz über eine Züchtung von Weinbergschnecken findet sich bei Marquart
(Marquart, 1909), wonach der Gesamtwert der im Donautal geztichteten Schnecken 1909
sechs Millionen Mark betragen haben soll. Andere Angaben beziehen sich meistens
auf die Mast der Tiere: Weinbergschnecken wurden im Frühjahr und im Sommer in
freier Wildbahn gesammelt, gefüttert und im Herbst als Deckelschnecken verkauft.
Gehege zu solcher Schneckenmästerei besassen bereits die alten Römer, später im
Mittelalter besonders die Klöster, da die Schnecken vonder Mönchen als Fastenspeise
sehr geschätzt wurden.

Der wissenschaftliche Nachweis der Züchtungsmöglichkeit von Helix pomatia wurde
erstmals von der Dipl. BiologinG. Heinerbracht (Hein, 1952). Dr. G. Nietzke (Nietzke,
1963) und Dr. K. Königer (Königer, 1965, 1966, 1967) bestätigen eine gewinnbringende
Züchtungsmöglichkeit unter bestimmten Voraussetzungen. Seither haben sich viele
Züchter auf diesem neuen Gebiet der landwirtschaftlichen Sonderkulturen mit wech-
selndem Erfolg versucht. Die hervorstechendsten Erfolge hat wohl F. J. Jungwirth
auf seinen zwei Hektar grossen Anlagen auf der Schwäbischen Alb erzielt (Jungwirth,
1967), aber auch aus Österreich werden erste Erfolge gemeldet (Nawratil, 1963, 1964,
1965, 1966, 1967, 1968; Fröschl, 1968; Juza, 1968). In den Oststaaten sind mit grosser
Wahrscheinlichkeit mehrere staatliche Versuchsanlagen mit der Verbesserung der
Züchtungsmöglichkeiten von Helix pomatia beschäftigt. Das Interesse an diesem
kleinen Tier, das grosse Devisen bringen kann, ist allerorts vorhanden.

2. Biologie

Die Tiere überwintern in einer selbstgegrabenen Erdhöhle im Freien. Ab etwa Ende
Februar besteht eine Bereitschaft zum Erwachen aus dem Winterschlaf. Das aus-
lösende Moment ist mit grosser Wahrscheinlichkeit eine Resultante aus der Kombina-
tion der beiden Faktoren: Temperatur und Luftfeuchtigkeit, bezw. Bodenfeuchte.
Versuche, welche die Tageslänge für das Erwachen aus der Winterruhe verantwort-
lich machen wollen, sind im Gange, jedoch halte ich diese für weniger aussichts-
reich. In unseren Breiten erwachen die Schnecken in der Regel im April/Mai. Bald
nach der ersten Nahrungsaufnahme, noch im Mai-Juni, erfolgt die Copulation, welche
mit wechselseitiger Befruchtung abschliessen kann. Im Juli werden die Eier in eine

NAWRATIL 137

selbstgegrabene Eihöhle in den Boden
gelegt (maximale Beobachtungsziffer
einer einzigen Eiablage: 105 Stück), im
Durchschnitt 50 bis 70 Stück. Nach etwa
drei Wochen schlüpfen die Jungtiere,
verbleiben meistens noch einige Wochen
in der Eihöhle, wo die Eihäute auf-
gezehrt und Erde gefressen wird.
Frühestens Mitte August kommen die
Jungschnecken in einer feucht-warmen
Nacht erstmals an die Oberfläche. Im
ersten Jahr lassen sie sich bei
Tageslicht kaum blicken; unter den Am-
phibien, Reptilien, Vögeln und Säugern
gibt es viele, die das zarte Fleisch von
Jungschnecken zu schätzen wissen. Bei
Tagesanbruch suchen diese daher gut
geschützte Schlupfwinkel auf oder sie
gehen überhaupt wieder in den Boden
hinein. Mit drei Jahren werden sie
geschlechtsreif. Die Verkaufsgrösse er-
langt ein Teil der Tiere bereits mit
zwei, der Rest mit drei Jahren. In
freier Wildbahn sterben die meisten vor Erreichung der Geschlechtsreife ab. In
Farmgehegen muss den Faktoren, welche diese Sterblichkeit verursachen, entgegenge-
wirkt werden.

3. Mortalität

a) Bakteriologische, virologische und histologische Untersuchungsergebnisse

Untersuchungen am Hygiene-Institut der Universität Wien (Nawratil & Loew, 1968)
ergaben, dass die untersuchten Krankheitserscheinungen von Helix pomatia, welche
mit einer Muskelstarre beginnen und schliesslich den Tod der Tiere herbeiführen,
nicht bakteriell verursacht werden. Eine wie immer geartete bakterielle Infektion
liegt nicht vor.

Die virologischen Untersuchungen ergaben eindeutig, dass keine auf Warmblütler
übertragbare Vireninfektion vorliegt. Wenn die Anwesenheit eines gastropoden- oder
vielleicht sogar artspezifischen Virus auch nicht mit völliger Sicherheit ausgeschlossen
werden konnte, weisen die erzielten Ergebnisse in Zusammenhangmit vielen Beobach-
tungen der Tiere und des Krankheitsverlaufes im Biotop doch mehr auf eine Toxin-
bildung in den erkrankten Tieren hin, die dann eine Sekundärerscheinung darstellte.
Bei Überimpfung von Pressafthomogenaten erkrankter Tiere auf gesunde lösen diese
Toxine u.U. die gleichen Krankheitssymptome aus. Diese Hypothese wird bis zu einem
gewissen Grad auch durch die histologischen Untersuchungen gestützt, welche keinerlei
Differenzierungen oder pathologische Veränderungen des Gewebes erkrankter Tiere,
wie solche durch Virenbefall in der Regel bewirkt werden, gegenüber demjenigen
gesunder erkennen liessen.

b) Klimatische Faktoren

Es ist daher mit grösster Wahrscheinlichkeit anzunehmen, dass die Ursache der
Erkrankungen im Einwirken ungünstiger klimatischer Faktoren auf die Tiere zu
finden ist. Die diesbezüglichen Untersuchungen sindnochim Gange. Es wird vermutet,
dass die Resistenz der Tiere eng mit der Bildung der bakteriostatischen Substanz

138 PROC. THIRD EUROP. MALAC. CONGR.

(Loew € Nawratil) in der Eiweissdrüse zusammenhängt, welche während Ruheperioden
(sommerliche Trockenstarre und Winterruhe) entsteht. Es könnte sich dabei um
dieselbe Substanz handeln, welche ais “Апи-Анр’ bezeichnet wurde (Prokop, 1967,
1968) und mıttels welcher menschliches Blut gewisser A -Gruppen und Bakterienstämme,
welche endständig nichtreduzierend gebundenes N-Acetyl-D-Galaktosamin in der Zell-
wand tragen, agglutiniert wird. Es liegt nahe, dass eine Substanz vorhanden sein muss,
welche die Entwicklung von Darmbakterien und Gárungserregern - bes. wahrend der
sommerlichen Trockenstarren bei relativ hohen Temperaturen - verhindern kann.
Würde diese Substanz jedoch nur während oder besonders am Beginn von derartigen
Ruheperioden gebildet, dann müsste während und nach einer Witterungsperiode welche
keine Ruhepause induziert (z.B. lang anhaltende Regenfälle), eine grössere Mortalität
auftreten. Ebenso dürfte die Möglichkeit der Bildung dieser Substanz zeitlich und
quantitativ beschränkt sein, so dass nach Ablauf einer gewissen Periode eine neuerliche
Aktivitätsentfaltung mit Nahrungsaufnahme erfolgen muss, um den Stoff neu bilden zu
können. Währt eine Trockenpause also zu lange, so tritt ebenso wie bei fortdauernder
nasser Periode eine grössere Sterblichkeit auf. Da durch höhere Temperaturen der
Gesamtstoffwechsel eine erhebliche Steigerung erfährt, können Trocken- und Hunger-
perioden in der Regel im Sommer nicht in der gleichen Länge überdauert werden als
im Winter.

Tatsächlich konnte in den Jahren 1961-1968 unter den beschriebenen Umständen
sowohl in den Freigehegen der Versuchsanlagen wie auch unter markierten Tieren in
der freien Wildbahn ein Ansteigen der Mortalitätsrate - 20-80% des oft in die Tausende
gehenden Untersuchungsmaterials - beobachtet werden.

NOTWENDIGE MASSNAHMEN - AUSBLICK

Der Einfluss klimatischer Einwirkungen - Dauer und Stärke - besonders von Tem-
peratur und Luftfeuchtigkeit auf die Bildung der bakteriostatischen Substanz (vermutlich
das Anti-Ayp oder eine eng damit verwandte Substanz) muss an einem statistisch
repräsentativen Material von Helix pomatia untersucht werden. Dies ist, sollen die
Ergebnisse nicht durch Zufall und Glück allein begünstigt werden, nur in einem In-
stitutsbetrieb möglich. Zur Beschleunigung der Beobachtungen sind Klimakammern,
bezw. Räume, in welchen Temperatur und Luftfeuchtigkeit regulierbar sind, not-
wendig. Die Arbeitsgrundlage eines solchen Institutes müsste für mindestens zehn
Jahre gesichert sein, da Helix pomatia mit drei Jahren Geschlechtsreife erlangt und
die Nachkommenschaft bis zur Е. verfolgt werden sollte. Durch eine Regulierung des
Kleinklimas nach den gewonnenen Erkenntnissen wird eine wirtschaftlich interessante
Auswertung mit viel grösserer Sicherheit als heute möglich sein, ähnlich, wie dies bei
der Fisch- und Austernzucht bereits jetzt der Fall ist.

SUMMARY

Among other central European countries Austria is exporting snails (Helix pomatia)
to France. The yearly income for Austria resulting from this snail export business
is about 3 million Austrian shillings and is limited only by the amount of available
snails, not by a lack of buyers. Breeding of these animals would be interesting for
both the breeder and the Austrian State. The scientific proof of the breeding possi-
bility was done first by G. Hein in 1952. Since then a lot of people tried their luck
breeding snails economically. However, because ofadisease that sometimes caused a
high mortality rate amongst the animals, the breeding results were not always the
expected ones. As it was not known whether this disease was caused by bacterial in-
fection or not, investigations had been carried out.

NAWRATIL 139

Results

1. No bacteria-infection could be traced either with sick or with healthy animals.
On the contrary, a substance bacteriostatical or even bacteriolytical to certain groups
of bacteria (such as containing N-Acetyl-D-Galactosamine) could be noticed.

2. It was proved that there is no infection of a virus transmittable to mammals.
A virus transmittable from sick to sound snails could not be proved. Histological
investigations did not show any difference in the tissues of sick and sound snails.
Although the possibility of a virus specific to gastropods or even to Helix pomatia
causing the mortality was not fully discarded, the results of the virological investi-
gations together with observations of the ecological and environmental nature pleaded
for a toxical poisoning of sick snails.

3. The primary cause of the sickness most probably is to be found in climatic
factors (temperature and moisture) suchas not enough change in dry and humid periods.

4. Most probably the resistence of the animals depends on the bacteriostatic sub-
stance which is built in the beginning of inactive periods (dry weather periods during
the summertime, and hibernation). It is suggested that this substance in the protein
gland is the same or at least a very similar one than being described by Prokop as
Anti-Ayp-

5. A 10-year research program, to be carried out in an adequate institute, is pro-
posed to clear all open questions and makethe breeding of Helix pomatia a prosperous
business,

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antikörperähnlicher Verbindungen. D. Deutsche Gesundheitswesen, 23: 318-320.

QUEVAUVILLER, A., MAINIL, J. & GARCET, S., 1953, Le mucus d’Helix pomatia.
Rev. de Pathologie générale et comparée, 1953: 1514-1539.

NAWRATIL 141

RACKWITZ, A., SCHLESINGER, D. & PROKOP, O., 1965, Uber ein Blutgruppen-
prinzip В (Anti-A) bei Helix hortensis. Ein neuer menschlicher A-Rezeptor
Ahel. Acta biol. med. germ., 15: K187-189.

UHLENBRUCK, G., PROKOP, O. & HAFERLAND, W., 1966, Agglutination von E. coli

durch ein Agglutinin aus Helix pomatia. Zentrbl. Bakt., Parasit., Infektionskrkh.
u. Hygiene, 1 Orig. 199: 271-272.

UHLENBRUCK, G., SCHMID, D. O. € PROKOP, O., 1966, Uber die Natur des A-hel

Rezeptors an menschlichen und tierischen Blutkörperchen. Acta biol. med. germ.,
16/1: 9-12.

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MALACOLOGIA, 1969, 9(1): 143-151

PROC. THIRD EUROP. MALAC. CONGR.

DISTRIBUTION AND ECOLOGY OF THE FRESH-WATER SNAILS
(GASTROPODA) OF NORWAY

Jan Okland

University of Oslo, Norway
(Dental Faculty, Department of Anatomy, Blindern, Oslo 3,
and Zoological Museum, Sarsgt. 1, Oslo 5)*

ABSTRACT

The article is a preliminary report of some of the results arrived at in a study
comprising the distribution, ecology and morphology of the fresh-water snails of
Norway, including aspects of regional limnology. When finished, tne study is expected
to be printed in Folia Limnologica Scandinavica.

Fresh-water snails and data on environmental factors have been collected in about
1,350 lakes, rivers, ponds and other topographical types of water bodies. The distri-
bution patterns of the various species are discussed in relation to: (1) possibilities
for immigration following the last glaciation, and (2) present-day environmental factors
(topographical type of habitat, altitude above sea level, geology, vegetation in the
surroundings, macrovegetation in the water, substratum, wave exposure and physical
and chemical factors in the water (pH, content of calcium, etc. )).

This is a preliminary report of some ofthe results arrived at in a study comprising
the distribution, ecology and morphology of the fresh-water snails of Norway, in-
cluding aspects of regional limnology (Okland, in preparation).

Many data have not yet been fully evaluated and maps and diagrams are still in-
complete. In this report a certain emphasis will be put on the background for the
investigation, and on some of the methods and principles employed.

For the planning of the study two papers were of special importance, those of
Boycott (1936), dealing with the habitats of fresh-water Mollusca in Britain, and of
Hubendick (1947), considering the distribution and ecology of the fresh-water gastro-
pods in South Sweden. These two studies had shown that the distribution of fresh-
water gastropods could be correlated with certain factors of environment. The
importance of the various factors Seemed nevertheless to be different in the two
areas. It was also evident that neither Britain nor South Sweden presented such a wide
variety of habitats within a small geographical area as that which occurs in south-
eastern Norway. Here the gradient from lowland districts to high mountain areas,
up to more than 2,000 metres above sea level, is of great ecological significance.
Also, - and I consider this still more important - in the lowland part of southeastern
Norway we find the region which geologically is called the Oslo Region. This fairly
small geographical area has an unusually wide variety of bed rock and Quaternary
deposits which greatly influence hydrochemical and biological factors in its numerous
water bodies. In the present study this southeastern part of Norway has been es-
pecially closely studied.

The material was mainly collected during field studies carried out in 1953-57 and
1960-62 (the years 1958-59 were devoted to studies in a single lake and its environs,
cf. Okland, 1964). Of the about 1,350 habitats investigated, some 850 were sited in
lakes, the remaining ones being sited in (or consisting of) ponds, ditches, mires,
puddles, and slow-flowing and rapid flowing rivers. In all habitats investigated
several factors of environment were measured. About 60,000 specimens of gastropods
were collected and brought to the laboratory for closer examination.

*Present address: Department of Limnology, University of Oslo.

(143)

144 PROC. THIRD EUROP. MALAC. CONGR.

No.1 (LAKES)

No.2 (PONDS, ETC.)|

OF TOTAL NUMBER

DETECTED IN EACH HABITAT )
h
O
T

°/o

NUMBER OF SPECIES DETECTED

(AS

1 it >)
O 25 50 SO 100 °/o
TIME SPENT IN COLLECTING
(AS *% OF TOTAL TIME USED
IN EACH HABITAT)

FIG. 1. Evaluation of the collecting efficiency in 1956, showing how the number of species detected in a
given type of habitat increases with the time spent in collecting. The curves represent average values for,
respectively, (1) 81 lakes, and (2) 49 ponds, puddles, ditches and mires.

The collecting of gastropods was restricted to shallow water, down to a depth of
about 1.5 m. The major collecting device among vegetation and on soft bottom was a
sieve mounted on a rod, about 1.8 m in length.

The habitat was the smallest unit investigated in the field. In each lake or river
usually only one habitat was investigated. The habitat may be defined as a place where
gastropods were sought and certain ecological factors measured and classified. In
lakes and rivers the habitat consists of a certain stretch of shore - usually about
200 m - defined by special ecological characteristics. The average investigation
time per habitat in lakes and rivers was 1 hour. For the smaller water bodies like
ponds and puddles, the entire water body was investigated and considered as one
habitat.

Experience soon showed for how long each habitat had to be investigated in order

to obtain a satisfactory idea of the number of species present. Fig. 1 indicates how
the number of species detected in a given type of habitat increases with the time spent
in collecting. It also represents an evaluation of the collecting efficiency. The dia-
gram refers only to habitats investigated in a special year. For the smaller water
bodies, 97% of the total number of species found was encountered during the first
half period of collecting, and not a single new species was found during the last 25%
of the total collecting time. For the lakes, however, we note that the time interval
covering the last 25% of total collecting time yielded a 5% increase in new species.
Table 1 indicates the name of the 27 species of fresh-water gastropods present in
Norway, and summarizes their main geographical distribution. A survey of my
material as regards number of specimens collected and number of habitats where a
given species was found is included.

There are two major factors determining the distribution patterns of the fresh-
water gastropods: (1) dispersal abilities connected to the immigration following the
last glaciation, and (2) present-day environmental factors in the fresh-water habitats.

The distribution patterns of species listed in column C (Table 1) seem to be related
to barriers of dispersal. These species are present in the south of Norway and in
the north of Norway, but they are lackingin areas in between, and also lacking in most
parts of the western coastal areas. Among the fresh-water plants and the fresh-

OKLAND 145

TABLE 1. The fresh-water snails of Norway, with major geographical distribution ranges.
Sources: The author’s material, literature records, and museum collections (the
latter still under revision).

The Author’s Material
(Preliminary figures)

Type of
distribution
in Norway®

Number of speci- |Number of habitats

mens collected with the species
Family: Lymnaeidae
Lymnaea stagnalis (L.) 1,450 93
L. palustris (Mull. ) SOS SS 1,050 45
L. truncatula (Mull. ) А - - - - - - 3,200 405
L. glabra (Miill. ) D 1,750 71
L. peregra (Müll.) A= =e Se 15,550 788
i. auricularia (№. ) Ss. “str. --C---- 485 3
L. glutinosa (Müll. ) ---- - - 50 3
Family: Physidae
Physa fontinalis (L. ) в 1,550 64
Aplexa hypnorum (Г. ) == Е = 500 24
Family: Planorbidae
Planorbarius corneus (L.)l ----E-- 200 6
Planorbis planorbis (L. ) = = - - E - - 39 2
P. carinatus Müll. = - = = E- - 65 2
Anisus spirorbis (Г. ) AN A 900 16
Bathyomphalus contortus (L.) - B- - - - - 6,050 370
Gyraulus acronicus (Férussac) = Bee => = 19,300 782
С. albus (Müll.) ---- E - - 170 10
G. laevis (Alder) = - - - - - а - -
@. erista (1. ) = B= == 2,450 112
Hippeutis complanatus (L. ) - = - - E- - 1,100 13
Segmentina nitida (Mull. ) Ss) ta == 150 1
Family: Ancylidae
Ancylus fluviatilis Mull. - - - - E- - 450 26
Acroloxus lacustris (L. ) - - - - E - - 1,000 38
Family: Viviparidae
Viviparus viviparus (L. yt 8
Family: Valvatidae
Valvata cristata Mull. 86
У. piscinalis (Mull. ) 99
У. sibirica Middendorff 7

Family: Hydrobiidae
Potamopyrgus jenkinsi (Smith)?

introduced c. 1890.

2A recent immigrant.

3A. Distributed in total Norway; В. Distributed in most parts of Norway;'C. Distributed in the
south and in the north, but lacking in areas in between and in most of the western coastal areas;
D. Distributed only in parts of South Norway (including Tróndelag), E. Distributed only in parts
of South Norway (lacking in Tröndelag); Е. Distributed only in the northern parts of Norway;
G. Distributed only in the western (Atlantic) parts of Norway.

146 PROC. THIRD EUROP. MALAC. CONGR.

LAKES FROM TOTAL NORWAY

TOTAL: 681
21 = —— 21
20! 20
13; 13
12. 12
11! A 11
_ 10. u. 10
59. = ¡9
AC sa mi 8
À 7 Sue 9, 7
Е . BUS 6
< . ONO
I5 ; Nec O Co ae 5
a 4) y . Ra en A td
о O = .. } a : . : |
mc) Е er, le a i
2 eee i° 8 be oe, 8 ÉS 2
: : de u 3 ne AE Es ; .
QUE = eee - dl 2 | Be nee ER 0
4.0 5.0 6.0 70 8.0 9.0 10.0
HYDROGEN-ION CONCENTRATION (pH)
LAKES FROM TOTAL NORWAY
TOTAL : 141
=> 5 if =] 5
E
2
а. 14
D
w 3 | 3
o
22 E
B ЕЕ ® ., e
— 1 A e e a
< . О
ol aR! oe ele
4.0 5.0 6.0 7.0 8.0 9.0 10.0

HYDROGEN-ION CONCENTRATION (pH)

FIG. 2. Values for total hardness and hydrogen-ion concentration in 832 Norwegian lakes. Each lake
is represented by one dot, based ona single surface water sample. The values for total hardness are given
аз °dH (1 °dH=10mg’CaO’/1. Method: EDTA). A: Lakes with gastropods. В: Lakes where gastropods
were not detected.

water fishes similar patterns of distribution are also found. Such species are mainly
distributed in areas with slow-flowing water connections between Norway and the
Baltic basin, from which a major part of the fresh-water organisms of Norway
probably came in late- and post-glacial time.

Although dispersal abilities at least to some extent may influence the distribution
patterns of gastropods, most fresh-water snails seem to be rather easily and freely
dispersed, mostly in a passive way. The major agent for the dispersal is probably
ducks and other water fowl. The main reason for presence or absence of certain

OKLAND 147

FREQUENCY DEVIATIONS IN RELATION TO
TOPOGRAPHICAL WATER TYPE

ZERO: EXPECTED VALUE IN RANDOM DISTRIBUTION

MM INCREASED FREQUENCY III DECREASED FREQUENCY
A LAKES
В. PONDS
ES A BC D E:F G C DITCHES
] | D: MIRES
o м. Ш м_ ГУМ МАЕА E: PUDDLES
TOM I Perecra
| UNI) | N = 549 Е: SLOW-FLOWING RIVERS
100 e G: RAPID u
50 Г
ом 2 + GYRAULUS
III] | ACRONICUS А ВЕ: DIEHE С A B'C D E:F G
— Wu М = 621
100
10

Бо :
3 ‘
Le LENA,
| | || М= 81
100 J z dd. Ш

BATHYOMPHALUS \
CONTORTUS WU: 12 py
М = 295 |
50 5 TW i
mau | ИА
0 TTT ый тг | PHYSA E Ш | Ш 1
| Il MIT ri FONTINALIS ps
AN | | N = 64 LYMNAEA PALUSTRIS ANISUS SPIRORBIS
on ‘ll L N = 35 М= 12
50 6 14 - 200
o + ; LYMNAEA
|| И STAGNALIS
| | | N=85 - 100
100 Ш
II mm lm = 0
_ HIPPEUTIS NU U ||
COMPLANATUS | al 1) UE
N=68 - M Ш. 100
APLEXA HYPNORUM LYMNAEA GLABRA
М = 24 6
25
ACROLOXUS р в 20
LACUSTRIS 15 fe 208 16
N=60 | :
| 100
VALVATA A mmt- 0 =
PISCINALIS A | |
М-58 и Ш |
100
LYMNAEA TRUNCATULA ANCYLUS FLUVIAT
М = 295 N = 2€

species of fresh-water gastropods is therefore connected with environmental factors
in the fresh-water habitats.

Of the many environmental factors affecting the distribution we may shortly mention
the total hardness of the water and the hydrogen-ion concentration. Fig. 2 shows
values for total hardness and pH in 832 Norwegian lakes. (On average the calcium
content of the water represents about 75% of the hardness values, the remaining part
mainly being due to magnesium.) We note that lakes in which gastropods were not
found in general are poor in lime and many of them are rather acid, with low pH-
values.

Considering the fairly restricted geographical area of southeastern Norway, we
may suppose that the distribution patterns here are mainly regulated by the different
environmental conditions. The remaining part of this very preliminary report per-
tains to this southeastern part of Norway, roughly corresponding to the Norwegian
concept of “Ostlandet.”

We shall first consider Figs. 3-5 dealing with “frequency deviations” and con-
structed on the assumption that within the small geographical area of southeastern
Norway the presence or absence of certain species of gastropods are due to the dif-
ferent environmental conditions.

Fig. 3 pertains to 955 habitats investigated in southeastern Norway, split up into
the different topographical categories A-G: Lakes, ponds, ditches, mires, puddles,
slow-flowing and rapid-flowing rivers. Only the 16 species which I have found in at

148 PROC. THIRD EUROP. MALAC. CONGR.

FREQUENCY DEVIATIONS IN RELATION TO

АВ СТР
= MACROVEGETATION IN THE WATER
_— 1 GYRAULUS
ACRONICUS
N=417 ZERO: EXPECTED VALUE IN RANDOM DISTRIBUTION
50 2 ШЕИ INCREASED FREQUENCY 1 DECREASED FREQUENCY
o № | LYMNAEA
III PEREGRA A RICH (QUANTITATIVELY AND QUALITATIVELY)
| N = 369 B u ( u )
er C: POOR MACROVEGETATION
D: SPHAGNUM BOG

3
LYMNAEA
0 MIT
| ЩО TRUNCATULA

N=107

100 4
LA | BATHYOMPHALUS ¡RS 7 8 “
| MT contortus |
: N = 218 Br
100 -
— He nn
UN WU

zu ШШ 100

ABCD ABC TD ABCD

LYMNAEA PHYSA LYMNAEA
PALUSTRIS FONTINALIS STAGNALIS
= 22 N=50 N=69
VALVATA
PISCINALIS
М = 56

LYMNAEA VALVATA ACROLOXUS APLEXA YRA
GLABRA CRISTATA LACUSTRIS HYPNORUM CRISTA
N= 24 N=63 N= 48 МЕ! 2

FIG. 4.

least 10 habitats are included. For each species black columns represent increased
frequency, shaded columns decreased frequency, and the zero level represents expected
frequency in random distribution. A decreased frequency of -100 represents complete
absence in the category in question. We note, for instance, that Lymnaea truncatula

(species No. 15) shows an increased frequency in the most shallow water bodies like
ditches, mires, and puddles, a decreased frequency in lakes, ponds, and rapid-
flowing rivers, and the frequency in slow-flowing rivers is very near that expected
in random distribution. The calculation of this expected value may be illustrated by
an example: Of the about 1,000 habitats investigated about 500 are lakes. Now,
since Lymnaea truncatula has been found in about 300 habitats in all, we might expect
that in a random distribution about one-halfofthese finds - that is about 150 records -
would be from lakes, since the lakes constitute one-half of the habitats investigated.
Instead, Lymnaea truncatula has only been collected in about 100 lake habitats, this
representing a decreased frequency in relation to the expected value of 150. This
decreased - or in other cases increased - frequency has been standardized in the dia-
grams in proportion to the different number of habitats investigated in each category,
thus enabling a comparison of frequencies between different categories. Fig. 3 also
indicates that Ancylus fluviatilis (species No. 16) has a tremendously increased fre-
quency in rapid-flowing rivers, decreased frequency in slow-flowing rivers, and com-
plete absence in stagnant waters (in Norway, this species does not occur in lakes as
it does in other countries). In Fig. 3 we also note that a great many species show a
tendency to a Slightly increased frequency in lakes.

OKLAND 149

FREQUENCY DEVIATIONS IN RELATION TO
TOTAL HARDNESS IN THE WATER

Nee ZERO: EXPECTED VALUE IN RANDOM DISTR!BUTION
fi | ШИ INCREASED FREQUENCY UN DECREASED FREQUENCY
O o lll GYRAULUS 1°dH- 10mg Ca0/!
| “ACRO NIE US
Ñ 5 al A 0-1°dH
por DA Ba
tor L Ч.
QE PEREGRA iS ra
] М= 369 D 5-21 -u—
100
100 3

0
| АВЕО
о |) LYMNAEA

[II au GLABRA 5
N=25
200 4
| | т

г. РНУЗА LYMNAEA LYMNAEA BATHYOMPHALUS ACROLOXUS
m FONTINALIS PALUSTRIS TRUNCATULA CONTORTUS LACUSTRIS
oe | N= 51 N=22 N = 105 N=217 N= 48

400
300 300
12 14 к.
200 4 200
0 T="
If
к |
100 un |
HIPPEUTIS VALVATA LYMNAEA VALVATA APLEXA GYRAULUS
COMPLANATUS PISCINALIS STAGNALIS CRISTATA HYPNORUM CRISTA
№55 N=55 N=69 М = 63 МЕ N= 51

Fig. 4 pertains only to lakes andindicates frequency deviations in relation to macro-
vegetation in the water. The lake habitats are grouped into 4 categories according
to how the macrovegetation in the water is developed: (A) rich macrovegetation,
both quantitatively (much plant material) and qualitatively (many plant species);
(B) rich macrovegetation, but only quantitatively (much plant material, but few species);
(C) poor macrovegatation, and (D) Sphagnum bog.

We note that all species of gastropods show decreased frequency in habitats domin-
ated by Sphagnum bogs, and most species also present decreased frequency in habi-
tats with poor vegetation (category C). Where the macrovegetation is rich both
quantitatively and qualitatively (as found in most eutrophic lakes), we note that the
frequency of most of the species tends to be greatly increased.

Fig. 5 also pertains to lakes only. It indicates frequency deviations in relation to
total hardness in the water. The lake habitats are grouped into 4 categories (A-D)
according to the value for total hardness. We note that most species are favoured by
a high content of lime salts in the water. Two species, Gyraulus acronicus (No. 1) and
Lymnaea peregra (No. 2), however, are not particularly affected.

If we consider the relation between gastropods and environment in general, we find
that although each species has its own way of reacting to the medium which surrounds
it, there are general trends common to many species. This implies that we can study
the importance of certain factors of environment in relation to the gastropod fauna as
a whole (cf. also Hubendick, 1947).

150

TABLE 2.

STR

WAVE SUBSTRATUM
EXPOSURE

PROC. THIRD EUROP. MALAC. CONGR.

Lakes in southeastern Norway and occurrence of gastropods. The environment is
treated from 9 different points of view (elevation above sea level, geology, etc.,
listed to the left). Each of these 9 categories is split up into groups, the elevation
above sea level, for instance, into 5 groups (0-99 m, 100-199 m, etc.). For each
group are indicated: (1) Total number of lakes investigated, (2) Mean frequency
deviation for the gastropods (a measure explained in the text, positive figures in-
dicating that the frequency is greater than expected in random distribution, negative
figures indicating a decreased frequency), (3) Mean number of species per lake, and
(4) Number of lakes with a given number of species.

NUMBER OF LAKES
WITH
GIVEN NUMBER OF SPECIES

LAKE ENVIRONMENT SES 0-2 SPECIES| 3-4 SPECIES| 5-12 SPECIES
Le я
Ё 28 28

ELEVATION
ABOVE
SEA LEVEL

UNALTERED CAMBRO-SILURIAN ROCKS
MARINE CLAY

ALTERED CAMBRO-SILURIAN ROCKS, ETC.
PRE-EOCAMBRIAN ROCKS, ETC.

GEOLOGY

CULTIVATED FIELDS (A)
PASTURE LANDS

BOTH (A) AND (B)
CONIFEROUS FOREST (B)
SUBALPINE BIRCH FOREST
REGIO ALPINA

VEGETATION
IN THE
SURROUNDINGS

RICH VEG. (QUANT. AND QUAL.)
RICH VEG. (QUANTITATIVELY)
POOR MACROVEGETATION
SPHAGNUM BOG

Z
1 Q
оЕ
<
OB
29
28
>

АТОМС ТНЕ
SHORE

GYTTJA
DY-GYTTJA
CLAY
STONES

BOTH SMALL (A) AND MEDIUM (B)
SMALL WAVE ACTION (A)
MEDIUM WAVE ACTION (B)
HEAVY WAVE ACTION

HYDROGEN-
ION
CONCENTRA-
TION

TOTAL
HARDNESS

TURBID WATER

CLEAR, COLOURLESS WATER

SLIGHTLY BROWNISH-YELLOWISH WATER
STRONGLY BROWNISH WATER

WATER
COLOUR
AND
TURBIDITY

OKLAND 151

In Table 2 such an aspect is presented. It refers to an investigation of 542 lakes
in southeastern Norway. The lake environment is considered from 9 different points
of view, as shown to the left. Each of these 9 major viewpoints is split up into dif-
ferent categories, and for each category are indicated number of lakes investigated,
mean frequency deviation based on gastropods which have at least 10 occurrences in
lake habitats, mean number of species per lake, and number of lakes with 0-2 species,
3-4 species, and 5-12 species (absolute number and percent).

If, for instance, we consider the elevation above sea level, we note that the frequency
of gastropods decreases from lowland districtsto areas of higher elevation. The mean
number of species per lake also decreases (from 4.0 to 1.9). In the two last alti-
tudinal groups comprising lakes located more than 500 m above sea level, none of
the lakes investigated contained more than 4 species of gastropods, the majority
having from 0 to 2 species.

Accordingly, Table 2 enables us to point out some general trends in the correlation
between major factors of environment and the occurrence of fresh-water gastropods
in southeastern Norway. It does not, of course, deal with the rather complicated
problem of interaction between different factors.

LITERATURE CITED

BOYCOTT, A. E., 1936, The habitats of fresh-water Mollusca in Britain. J. Anim.
Ecol., 5: 116-186.

HUBENDICK, B., 1947, Die Verbreitungsverháltnisse der limnischen Gastropoden in
Stidschweden. Zool. Bidr. Uppsala, 24: 419-559.

OKLAND, J., 1964, The eutrophic lake Borrevann (Norway) - an ecological study on
shore and bottom fauna with special reference to gastropods, including a hydro-
graphic survey. Folia limnol. scand., 13: 1-337.

OKLAND, J. (In preparation). Fresh-water snails (Gastropoda) of Norway. Their
distribution, ecology and morphology, including aspects of regional limnology.
(Provisional title). Folia limnol. scand.

cs a el Fart ah ! m
A а rad Y т NY ot

DARK ms “ AT y AL Bro AN ven _ | pe, lach

Ba E Essen vical мт EL ee eee te shard need
i wer adhe, (0,0 ur 0.8 amd) irn mii ar ar - À
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Re т u

о С Wr fetes Uy PAY y Нат OTE
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rn y Sa LL vr: IE Serra Ne tae Aes
oF ee MIN

MALACOLOGIA, 1969, 9(1): 153-162

PROC. THIRD EUROP. MALAC. CONGR.

SEVEN REPRODUCIBLE CHARACTERISTICS OF MECHANICAL BEHAVIOUR
IN THE SNAIL’S FOOT MUSCULATURE (HELIX POMATIA L.)

N. Postma

Department of Zoology, Catholic University,
Nijmegen, The Netherlandst

INTRODUCTION

At the First European Malacological Congress in London (Postma, 1962) we gave a
survey of the myogenic mechanisms that are responsible for a peculiar postural
function of certain molluscan muscles, as recorded by an extension-time kymogram:
tetanical activity as well as catch (Sperrung), respectively maintaining tension and
shortening, or yielding with a given resistance to a stretching load.

Our object was the Helix foot musculature whose functioning is governed by the
neurones of the cerebral and pedal ganglia and the intramuscular nerve net as well
as by a few synapses in the pedal nerves, described by Schlote (1955). For the prepa-
ration of the foot muscle and mounting it in the lengthening device we refer to Postma
(1962). We would like to introduce the three reasons which led Jordan to distinguish
two mechanisms: a. the specific functional division of labor existing between cerebral
and pedal ganglia: the former governing contractile (tetanical) activity (primarily via
inhibition), the latter catch (autonomic controlled loosening) (Postma, 1962); b. con-
traction exhibits an optimal temperature, i.e., heat reduces resistance-like viscosity
(Postma, 1962, appendix item 9; Jordan & Kipp, 1939); с. contractions superpose
themselves on the extension time-curve.

In addition, we observed an interaction between both mechanisms: on the one hand
the resistance may hinder movability (slackening as well as shortening), and on the
other hand a certain degree of catch will ensure an optimal support of the contractile
effect (Postma, 1962, appendix item 4). The distension which often introduces a
contraction was interpreted as a loosening* of catch in favour of shortening (Postma,
1962, appendix item 17). Jordan’s argumentation was weak in two respects: that the
kymogram reveals summatively part of both mechanisms inthe resistance registered,
and the role of the nerve net is unknown (Nieuwenhoven & Postma, 1969).

More convincing are results obtained from the ABRM* of Mytilus edulis L.: nerve
cells are absent (Deane & Twarog, 1957)!, C.A.* and catch are functions of different
groups of proteins, actin and myosin or these two together with paramyosin as the
third one (Rtiegg, 1960). These functions are abolished by specific substances: catch
by 5-HT* (Leenders, 1967b) and contraction by acto-myosin interaction inhibitors,
such as salyrgan (Portzehl, 1952) and thiourea (Rilegg, 1963). Catch and С.А. may be
measured separately, i.e., by the tensionor shortening remnant* (Jordan & Kipp, 1939)
and by peak tension* respectively. Moreover the ABRM lends itself to treatment by
modern technics (Leenders, 1967), such as glycerine-extraction (fiber model) and
quick release-recovery*.

tChange of the author’s address because of retirement: St. Annastraat 94, Nijmegen, The
Netherlands (private address).

*For explanation please see p 160, 161.

lRecently Dr. H. H. J. Jaspar (lab. of neurophysiol.) did not succeed in making nerve fibers
visible.

(153)

154 PROC. THIRD EUROP. MALAC. CONGR.

CORRECTION AND COMPLETION OF THE MODEL
OF CONTRACTILE AND CATCH MECHANISMS

According to Johnson et al., (1959) who reported catch by crystallization of para-
myosin when pH decreased for 0.1 unit (thread model) and as well C. A. producing
tension but not shortening, we proposed (Postma, 1962) a model including paramyosin
linkages (“bolt pins”) responsible for catch and linkages between actin and myosin
(“wheels”), which would be active during production of tension or shortening (sliding
filament hypothesis, Huxley, 1956). However, Leenders (1966) not only showed that
the peak tension but also the tension remnant increase with ATPase* activity. Since
the mechanisms are not independent, Leenders (1967a, b) was led to propose his
actomyosin-paramyosin hypothesis: one can better imagine aninductionby paramyosin
which prevents the contractile active actomyosin linkages from detaching. Moreover,
Leenders successfully estimated an interaction similar to that which we observed in
the Helix foot musculature. His contention is, therefore, in agreement with our func-
tional interpretation of the pre-contractile slackening (Leenders, 1967). Thus we
incorporate it into the sequence of activity stages which constitute a contraction. More-
over, we have inserted details obtained by proteolytic (Szent-Györgyi, 1953), structure-
protein combining (Huxley, 1965) as well as electron-optical (Hanson & Lowy, 1964;
Huxley, 1964) methods into the diagram shownin Fig. 1. Since smooth muscle exhibits
“dense bodies” instead of Z-membranes, we limited our diagram to a detail lifted
from a striated muscle sarcomere (a-b-c-d, between stage 2 and 3; Postma, 1962,
p 154, fig. 1E) and represented it in stages 1-6 as explained in the fine type which
follows:

Explanation to the model in FIG. 1

Stages of contraction (Proc. lst Europ. Malac. Congr. р 162, fig. 11 sub. e-f-p, p-q, q-r and
r-s): st(age 1. “resting length” (=r.1.). Stimulation between st. 1 and 2, followed by activation;
a. break of linkages (- +) allowing distension for 5% г.1.; b. myosin heads hook onto actine
sites again (st. 3); c. contractile activation (4, st. 4), causing filament sliding and shortening
(st. 5). Stimulation is stopped and relaxation follows (st. 6), unless catch (0-) makes it impos-
sible (st. 5-p’). Afterwards lysis ( { ) of catch is needed (st. 5-p”). Table between st. 3 and 4:
four columns, st. 1 to 6, L(inkages) (in percent of available head and site pairs), A(ctivated)
and С (atch).

THE REPRODUCIBLE CHARACTERISTICS

The kymogram of mechanical behaviour of the Helix foot is the summative ex-
pression of tetanic activity or its inhibition and of catch or its lysis (Nieuwenhoven &
Postma, 1969). This behaviour may be modified considerably by extension, which
necessarily implies the existance of a pronounced physiological change, whose site in
the neuromuscular system, however, is unknown; perhaps these changes would involve
sensory sources, synapses, neuromuscular junctions or pure myogenic sites (Búlbring,
1955; Rüegg € Tregar, 1966) As yet the snail’s foot musculature is too complex for
further analysis. More is to be expected from a study on the Mytilus ABRM, but little
is known about reactions to stretch by molluscan retractor and adductor muscles.
Thus the best data on stretch resistance are described in the following characteristic
behaviour of the Helix foot:

*For explanation please see p 161.

POSTMA 155

tt
A

SEELE

ESE
<<<“

ЕЕ.

a
Preece
=
ee
ee
=

105 %
nn

rn
ae
==

IZA
ee
EEEEIEX

zer

TE
ts
22233

Zar
то
ps

BR 100%
lasers

ar
ice
LESS
ЕЕ
22222.

fee
SM,
erietrrrst?

FIG. 1. Sequence of activity stages of a detail (ab) in a sarcomere in longitudinal section.
М = Myosin molecules aggregated to filaments by the ‘tails’ (T). \w = terminal ‘heads’ (H) (Hux-
ley, 1964). A = Actin filaments: 2 strings twisted around each other, alongside active sites (J)
to which the ‘heads’ may attach themselves, forming cross-bridges, which together constitute a
structural network; the heads have capacity to split ATP, too. == PM = Paramyosin: situation
of molecules unknown; capacity to induce catch of bridges, causing fixation of structuration.

1. Specific role of the pedal ganglia”

The functional division of labor between cerebral and pedal ganglia, with respect to
contraction and catch respectively, has been discussed previously (Postma, 1962).
However, it may be mentioned that the Helix foot as P-preparation* shows initially
a low resistance to deformation. Lengthening is quickly followed by a synchronized
catch: elongation starts nearly free, but ceases suddenly and at a certain niveau* is
maintained (Fig. 3-C heavy line parts).

2For Mytilus ABRM is only reported that the pedal ganglia cause autonomically a low catch level

(Twarog, 1960, 1967).

*For explanation please see p 160, 161.

PROC. THIRD EUROP. MALAC. CONGR.

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POSTMA 157

2. External resistance during shortening?

The influence of external resistance was likewise discussed previously (Postma,
1962). It suppresses restoration of the C.A./catch ratio present before shortening
was evoked (Postma, 1963, p 241).

3. The foot's reaction to lengthening

That extension itself changes the resistance to stretch was demonstrated via stimu-
lation of sufficient strength to abolish the resistance (Fig. 2). Our observation (Postma &
Mertens, 1966), that lytic stimulation - needed for completely counteracting resistance -
is lower than that for contraction, has been confirmed (Fig. 2A). The effect is not
pronounced and, therefore, understandably overlooked by Jordan at the start of his
experiments (Postma, 1942; Lowy & Millman, 1959a,b). The same is shown in Fig. 2B
curve 4 (3rd min). However, we had the impression that lengthening itself generates
catch, which may oppose the effect of lytic stimulation. Therefore, we repeated the
experiment (6th curve) switching-on excitation (1 min) 20 sec before the load was
applied. The elongation that normally is reached in 5 min takes now 2 min, and the
angle made with the abscissa is 3 times that without stimulation (48 i.st.o. 16°; cf.
also Fig. 2C). Next we investigated the effect of lytic stimulation of the pedal nerves
on the foot in resting condition (Fig. 2D). In order to do this, we first verified the
behaviour of the muscle without stimulation by placing it under a small stretching
load, insufficient to produce elongation; every reaction failed. Obviously detectable
activity is obtained only if the foot is lengthened, or shortly after. In the resting
muscle the linkages were stable.*

4, After-effects

Two such effects have been observed: one during recovery* (extending load removed),
and the other after lytic stimulation. Fig. 2E shows the initial fast recovery phase
subsequent to unloading, followed by a slower after-recovery (curves 2-5 on right
side). By lytic stimulation the quick recovery is retardable only; the second phase of
recovery Shows undermining (p, q) tending to reversal (s, t). Interruption of stimula-
tion initiates resumption of recovery. Our conclusion is, therefore: the lengthening
diagram as well as the recovery graphs reveal an active component. According to
Leenders (1966), catch is produced simultanously with C.A. That is, activity may
continue after removal of the load and contribute to recovery.

The after-effect of lytic stimulation is shown in the Figs. 2B and 2E. After the
effective stimulation (2B, curve 6) two resistance free contractions have been evoked,
each followed by registration of a lengthening kymogram (7th and 8th). The latter re-
peats the course of the consecutive curves 1-6 preceding lytic stimulation: the resis-
tance level* is restored, in contradiction with curve 7. In Fig. 2E, the lengthening
diagrams 7 and 8 show stimulation outlasting loss of resistance. The same holds for
the 7th recovery; its level did not return to that of the recoveries produced by un-
stimulated musculature. The after-effects might suggest the activity of centra that
produce these effects or the presence of certain substances (one which maintains
catch, another which causes lysis).

3The condition of absence of external resistance was reported earlier with respect to Pecten
adductor muscle (Bozler, 1930).

“Jordan (1930, 1935) distinguished stable and unstable catch as ‘old’ and ‘young’ viscosity.

*For explanation please see p 161.

1cm

158

1 min 5 10

FIG. 3. Two series of lengthening diagrams
obtained with 2 different Helix feet: 1 P-prepa-
ration (curves 1-8), the other an N-preparation
(1-5 and dotted lines 6-11). Both series begin
with curves characteristic for a “moderate”
extending load: No. 2 as well as 2-5 (~~, with
spread 1) repeat the type and course of the
first ones. The 3 next lengthening reactions
are obtained with half the ‘moderate’ load: the
asynchronous catch (dotted curves 6-8) de-
velops a proceeding increase of resistance
(level). In the P-preparation, the niveaux of
synchronized catch (heavy line-parts) shown
by curves 1 and 2 (p.1.) rise stepwise in Nos.
3-5, with transient shortening at still higher
niveau (a5). Afterwards lengthening is ге-
peated with double ‘moderate’ load, which
causes an opposite progression: gradual de-
crease of level (dotted graphs 9-11), stepwise
descendence of niveaus, often preceded by a
combination of catch and transient shortening
(ag and bg at p.1., ajo 2d niveau s.n.) at the
length reached by the extension that preceded
(according to adaptation? Cf. also Fig. 5,
14th-18th min); in curve 11 without contraction
(a11, 3d niveau t.n.).

PROC. THIRD EUROP. MALAC. CONGR.

9. Reactions to the extending load

The weight of the load also plays an
important role with respect to alteration
in the ratio between the number of link-
ages active in catch and С.А. (Fig. 3).
A small load emphasises catch develop-
ment, a large one excess of lysis. Asa
result, only lengthening with moderate
loads ensures restoration of the original
ratio C.A./catch by shortening, withthe
provision that it can take place indepen-
dently of external friction and that ex-
citation is accomplished with the aid of
‘indifferent’ stimulus strength. Thelat-
ter and the moderate load must be esti-
mated atthe beginning of each experiment
if one is to obtain a series of repeating
curves under otherwise unaltered con-
ditions.>
6. Interaction between catch and C.A.

Since we had the impression that a
high resistance to lengthening may either
limit the speed as well as amplitude of
contraction, or extremely low level
causes impotence, we attempted to mimic
that interaction by alteration of extending
loads. Such an experiment is shown in
Fig. 4. Indeed, there must be anoptimal
number of linkages guaranteeing suf-
ficient ‘internal support’ (Postma, 1967)
to develop resistance and shortening;
fewer cause failure and too many would
prevent normal movability.

7. Time, elongation and velocity

It struck us that critical situations -
reactive interruption of lengthening, ifit
is induced by maintenance of length, or
only in combination with collapse or
shortening - often occur subsequent to
certain time intervals, e.g., after start
of extension or its continuation and at
predisposed lengths. Two examples are
given in Figs. 5 and 6. It ordinarily
happens that interruption of resistance to
lengthening which is preconditioned by
stretch is finally overcome by lytic ac-
tivity, i.e., caused by stimulation of the
cerebral ganglia (in Fig. 5 before 18th
min), as well as by autonomic activity of
the pedal ganglia (Fig. 6, 4th min).

Jordan (1905a, b) had reported earlier the promotion of shortening induced by small loads and

lysis by large ones.

He therefore distinguished between ‘myogenic’ and ‘neurogenic’ catch.

POSTMA 159

variant: L
number :

FIG. 4. Curves from a P-preparation. Table in the right corner gives numbers of successive
extension curves and the loads (L) used: 10 g is nearly the indifferent load, 1 and 2 show critical
reactions аёр.1.; 3 and 4 respond at higher niveau, without progression. 20 g load causes break
through of p.1.; not earlier than after 4 min and nearly 4 cm lengthening catch is manifest again
(curve 5). Curves 6-8 with 5 g load show restoration of power to offer resistance and to develop
contraction: No. 6 with 2 failures to stop lengthening (respectively at p.1., and at 2d niveau s.n.)
and an after-effect of lysis (5th extension with 20 g load); No. 7 a failure at (*), contraction at
(x); No. 8 with restored power to lift 5 g and a transient niveau at p.1. Curve 9 with 10 g load:
the course of Nos. 1 and 2is not repeated, the restoration is not yet stabilized; thus after-effects
present.

SUMMARY AND DISCUSSION

We described the great variability of mechanical behaviour of the Helix foot muscu-
lature. Its reproducibility (plate length, restoration of C.A./catch ratio) and the vari-
ability being experimentally induceable (depending on weight of load and stimulation
strength), permits a hypothetical union of the behaviour and its scope under the 2
antagonistic effects mentioned earlier and its interaction. Extension of the foot
activates both C.A. and catch; if the load is small, development of resistance is
strengthened; a large load and weak stimulation promote lysis. An equilibrium between
both antagonistic effects ensures a certain resistance level. The duration and velocity
of lengthening will also be decisive for the mechanical behaviour (time-factor). Fast
lengthening promotes quick generation of catch andincrease of resistance until elonga-
tion is blocked. This effect occurs when the resistance is initially low, accruing
from the presence of pedal ganglia, warmthor certain seasonal conditions (e.g., hiber-
nation). An important question is how much the natural ratio bound/free actin sites
(‘structural condition’) at the beginning of the loading, differs from that required
to stop lengthening. The same holds for the critical-value of collapse. Pertinent in
this connection is whether specific substances (Postma, 1962, appendix item 10b) in
Helix foot are responsible for C.A. and make and break of linkages (depolarizors
like acetylcholine and 5-HT, ions like Ca**), and what are the sensitive sites might
turn out to be. With respect to the myogenic basis in Mytilus ABRM Leenders has

160 PROC. THIRD EUROP. MALAC. CONGR.

1 min Ul We 4g WA A, Фи 10

FIG. 5. Pairs of consecutive kymograms, each pair obtained from another Helix foot (V, VIII,
X and XII) C-preparation. Ordinates and abscissa as in Fig. 2. Left half: curves which show
tendency to prohibit that p.1. is surpassed. Right side: after restoration of the original condition
by resistance-free contraction, chemical stimulation is applied (11th min) to the cerebral gangli-
on. Just 6-7 min later occurs abandonment of р.1. (/), no matter whether at the end of the 13th
(VIII and X), 17th (V) or 18th min is re-loaded (XII). Thus destruction of catch requires a cer-
tain time; the effect is, however, considerable only when during 6-7 min ‘latency’ the foot re-
mained unloaded: catch generating lengthening was absent.

successfully observed a variability inmechanical response asa function of Ca** liber-
ated by different classes of stimulus®, C.A./catch interaction included (Leenders,
1967a, fig. 5 p 133, with optimal support by catch).

ABBREVIATIONS AND TERMS

ABRM = anterior byssal retractor muscle.

С.А. = contractile activity.

5-HT = 5-hydroxytryptamine = serotonine. The mechanical behaviour of the snail’s
foot muscle is the result of С.А. and catch of the actin-myosin linkages. Slacken-
ing requires linkage break via catch release (= lysis) or loosening. A lytic
phenomenon reveals lysis e.g., caused by stimulation or accompanying contrac-
tion. Under isotonic conditions C.A. produces shortening, isometric registration
delivers tension. In smooth musculature its maximum is characteristic for the
response to a very definite excitation, knownas ‘peak tension’ (Fig. 2E). Slacken-
ing is measured as tension decay via the ‘tension remnant’ at certain intervals
after peak tension. Or it is recorded under isometric conditions via an extending
load as lengthening-time curve. Its course is dependent on the presence of
nervous centra. We distinguish:

C-preparations = with intact collar ring;

P-preparations = after removal of the cerebral ganglia under control of pedal ganglia;

N-preparation = under influence of nerve net only. The latter produce an extension
kymogram typically different from those developed by P- and C-preparations
(Figs. 3 and 5): the resistance to Stretchis measurable via the slope of the curves
(angle with abcissa), according to asynchronous C.A and catch, which show a

6Cf. also: BULLARD, Belinda, 1967, The nervous control of ABRM of Mytilus edulis. Comp.
Biochem. , 23: 749-759.

POSTMA 161

gradual and prolonged increase in re-
sistance. It is distinguished as ‘level’
from ‘niveau’ or length secured by
synchronized catch, characteristic for
P- and C-preparations. That шуеам 1$
conditioned by the length to which the
foot permitted stretching taut and was
pinned out on the wax plate before and
during dissection (cf. p(late) l(ength)).
After removal of the extending load,
the Helix foot partly reshortens ( =
‘recovery’) because of the tension
present. The same occurs when under
isometric conditions the muscle isal-
lowed to distend suddenly (‘quick

| 5 release’), assumed that C. A. has not
ue ves А yet stopped ( = ‘q.r.-recovery;).
5/min ВА 12/min АТР = Adenosine Tri-Phosphoric acid;
the energy rich P-bonds can be split
FIG. 6. Consecutive extension curves ob- by the enzymatic capacity of acto-
tained from one Helix foot: Nos. 1 and 2 as P- myosin-ATPase, under placing the
preparation, No. 7 after extirpation of pedal energy at the disposal of the filament-
ganglia. Critical elongations at the niveaux sliding mechanism (C. A.).
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ZUSAMMENFASSUNG

Einige Reaktionen der isolierten und in Verbindung mit höheren Nervenzentren
stehenden Fussmuskulatur der Weinbergschnecke auf a. Dehnung, b. Grösse der
Dehnungslast und c. Unterbrechung der Dehnung, werden beschrieben. Hierbei
fallen Gesetzmässigkeiten bei bestimmten Längen und Zeiten auf. Dieses
mechanische Verhalten der Helix-Fussmuskulatur wird unter Berücksichtigung
der Befunde LEENDERS am ABRM der Miesmuschel diskutiert.

MALACOLOGIA, 1969, 9(1): 163-171

PROC. THIRD EUROP. MALAC. CONGR.

PHYLOGENETIC INTERRELATIONSHIPS AMONG FAMILIES
OF BIVALVE MOLLUSCS

R. D. Purchon and D. Brown

Department of Zoology and Computer Unit, Department of Mathematics,
Chelsea College of Science and Technology, University of London

INTRODUCTION

One of us (R.D.P.) has been responsible for the zoological aspects of the investiga-
tions reported in this paper, including accumulation of data, drafting the questionnaire
and interpretation of the information supplied by the computer program. The remainder
of the work, including the drafting of computer programs, the encoding of the raw data,
and the handling of the computer, hasbeenthe responsibility of the other (D.B.).

We would like to express our thanks to Dr. M. E. Solari, of the Department of
Mathematics, Chelsea College of Science and Technology, for her very helpful advice
on methods adopted in the investigation.

THE TRADITIONAL, INTUITIVE APPROACH

Cox (1960), reviewing attempts to classify the Bivalvia during the last 200 years,
observed that zoologists are still divided in their opinions even as to the name of the
class! The terms “Lamellibranchiata” and “Pelecypoda” are not strictly applicable
to all members of the class, andthe older, Linnean term “Bivalvia” is more appropri-
ate from a descriptive point of view. We follow Cox in using the Linnean term
“Bivalvia,” and pray that other names for the class be abandoned.

Two centuries after Linnaeus’ Systema Naturae, and one century after The Origin
of Species, we seem to have made little progress in our attempts to produce a natural
classification of the Bivalvia. Most of the classificatory systems reviewed by Cox
(1960) are little more than clerical systems based on only one or two organ systems
such as the shell, the ligament, hinge teeth, pallial line, mantle fusion, siphons, ctenidial
structure, ctenidial frontal ciliation, stomach structure, etc. These various classi-
ficatory systems agree or conflict with each other to greater or lesser extent accor-
ding to the taxobases employed. Cox concluded from his review that “The history of
bivalve taxonomy ... has been one of continual disagreement as to which characters
are of real taxonomic value; that is, which give the most reliable clue to phylogenetic
affinities.”

We propose to comment briefly on only a few of the more interesting classificatory
systems, as follows: The system of Thiele (1935) is unsatisfactory in three respects.
The Nuculacea and Arcacea are not closely related and should not be associated in
the order Taxodonta; the Protobranchia, in fact, should be assigned to a separate sub-
class (Owen, 1959; Purchon, 1959; Yonge, 1959). The term “Anisomyaria” is unsuit-
able for an assemblage which includes the Dimyidae and does not include all aniso-
myarian bivalves. Finally, Trigonia is a filibranch, and should not be included in an
order named the Eulamellibranchia.

The systems of Pelseneer (1891, 1906, 1911) arebased on gross ctenidial structure.
The ctenidia, as organs of feeding, are liable to exhibit adaptive changes and are ac-
cordingly ill-suited as markers of phylogenetic relationship. Ridewood (1903) showed
that union of adjacent ctenidial filaments could be arranged in five stages, i.e., by
inter-locking ciliated discs (two stages) and by organic unions (three stages). In

(163)

164 PROC. THIRD EUROP. MALAC. CONGR.

four families, the Arcidae, Anomiidae, Aviculidae and Spondylidae, some species had
advanced in this respect one stage beyond the remainder of the family. This is strong
evidence of parallel evolution by a number of phylogenies through a series of “func-
tional strata” (Figure 1) (Ridewood, 1903; Purchon, 1960a). The distinction between
Filibranchia and Eulamellibranchia is a gross over-simplification.

Atkins (1938) distinguished two categories of bivalves, according to the types of
cilia found on the frontal surfaces of ctenidialfilaments. It is difficult to accept Atkins’
judgement that the latero-frontal cilia of the Ostreidae are “anomalous” on the basis
of the evidence published, and it appears that this conclusion was reached on other
grounds with a view to placing the Ostreidae where оп a priori grounds Atkins thought
suitable.

Classification of the Bivalvia by sub-division into progressively smaller units has
not been very successful. An archaic feature may have been lost independently in
many different phylogenies, and an advanced feature may have evolved independently
in more than one phylogeny. Sub-division of the class according to the occurrence of
such organs could produce very different results according to the relative importance
assigned to each variable. It follows that little may be achieved by attempting to col-
late the available classificatory systems, each of which is based on subjective
appraisals of a restricted range of anatomical variables.

An alternative approach to classification is to cluster genera into families, families
into sub-orders, etc., according to the available evidence. This depends on a sub-
jective appraisal of the reliability of the evidence; what is the statistical probability
of a given organ, or complex of organs, evolving independently in two unrelated phy-
logenies? If this probability is sufficiently low it can safely be disregarded. One of
us (R.D.P.) has been taken to task on the validity of this line of reasoning (Ghiselin
etal., 1967), but remains unrepentant. The families Tellinidae, Psammobiidae,
Donacidae, Semelidae and Solecurtidae possess a cruciform muscle and partly on the
basis of this information the first four of these families are clustered together in the
order Tellinacea (Graham, 1934, 1934a). The Solecurtidae are doubtless derived from
the same origins. The presence of a shell apophysis, and the insertion of the pedal
muscles on to this apophysis, in the families Pholadidae and Teredinidae offer good
grounds for grouping these two families in the order Adesmacea. The proposition
that the common possession of such features is evidence of descent from a common
ancestry, carries sufficiently high probability for acceptance.

When we turn to the occurrence of a postero-dorsal stomach caecum, appendix, or
wood-storing caecum, onthe other hand, we areon more difficult ground. These organs
are judged to be homologous (Purchon, 1941, 1960) and this indicates that their pos-
sessors are related by descent from a common ancestor. This does not necessarily
indicate close relationship between the orders Tellinacea and Adesmacea, for a ho-
mologous stomach caecum has also been found in certain species of Mytilus, Ostrea,
and Lima (Reid, 1965; Dinamani, 1967). This suggests that the stomach appendix
(=caecum) may be an extremely archaic structure which may have been possessed by
all, or very many, bivalves in the remote past, but which has been independently lost
in the majority of lineages.

To summarise, these contrasted and complementary methods of elaborating a phylo-
genetic classification of the Bivalvia do not seem to have taken us very far towards
our objective. The most that has been achieved by attempts to sub-divide the class
into smaller categories has been the isolation of the Protobranchia in a distinct sub-
class. Some success has been achieved in the clustering of families into orders (we
have not attempted to review the whole of this field of endeavour), but much remains to
be done. à

In drafting a classificatory system it is sound scientific procedure to use one’s

PURCHON and BROWN 165

EULAMELLI-
:BRANCHIA

SEPTIBRANCHIA PSEUDOLAME -

(CARNIVOROUS, :LLIBRANCHIA
SCAVENGING )

FILIBRANCHIA

PROTOBRANCHIA POLYSYRINGIA
( DEPOSIT- (FILTER-FEEDING )

PROTOBRANCHIATE

ANCESTOR

FIG. 1. Diagrammatic representation of the probable course of the early stages of adaptive
radiation of bivalve molluscs, on the basis of the feeding mechanisms adopted. The terms “Fili-
branchia”, “Pseudolamellibranchia” and “Eulamellibranchia” represent a sequence of functional
strata through which many lineages of filter-feeding bivalves may be evolving independently.

JATRINA
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COEFFICIENT OF SIMILARITY

DENDROGRAM OF SELECTED
BIVALVE GENERA

----------------

FIG. 2. Due to inadequacy of data from any one source it was necessary to combine informa-
tion from Arca similis and from Anadara granosa to form the lineage “Arca/Anadara.” Anadara
is a sub-genus of Arca, and the two species are comparable in being members of the superficial
in-fauna and in lacking byssal attachment in the adult state. It was similarly necessary to com-
bine data from different sources to form the lineage “Pinna/Atrina. ”

166 PROC. THIRD EUROP. MALAC. CONGR.

intuition and thereby avoid unnecessary expediture of time and energy in the laborious
accumulation of data which may ultimately prove useless. Our previous remarks,
therefore, should not be regarded as being unappreciative of the efforts of our prede-
cessors. As regards the phylogenetic classification of the Bivalvia, however, such
intuitive selection of evidence has not been generally successful. It is possible that
the emergence of the highly efficient filter-feeding habit led to an immediate, explosive
radiation with the simultaneous production of many independent lineages, few of which
underwent subsequent major sub-division. If this had been the case there would be
few examples of close phyletic relationship between pairs, or among groups, of
families, and all attempts to detect phylogenetic groupings of families would be doomed
to failure. This is by no means impossible.

Alternatively, perhaps, there may be phyletic groupings of families evidence of which
lies in subtle combinations of characters rather thanin the crude presence or absence
of only one or two characters. If so, such phyletic relationships could only be revealed
by the detailed analyses of large numbers of characters which can now be made with
the aid of computers. Before pursuing thisfurther we must refer to an observation by
Ridewood (1903). Although Ridewood drew up a system of classification on the evidence
supplied by his very extensive review of the structure of the ctenidia of bivalves, he
regarded this as being no more than one contribution towards a solution of the problem.
After many other reviews had been made of other organ systems, Ridewood envisaged
the results of all these reviews being compared, a definitive classificatory system being
produced from all the evidence. Ridewood doubtless had not considered the vast scope
of such an exercise, the extent to which evidence from different organ systems would
be in conflict rather than in harmony, or the great aid which would eventually become
available through the use of computers. Undoubtedly, however, his view was right.
Now, perhaps, we are beginning to approach the time when an attempt can be made to
review the whole evidence, and this paper is a preliminary report on current work at
Chelsea College of Science and Technology on this subject. The chief purpose of this
paper is to ascertain whether the procedures adopted are capable of producing meaning-
ful results and, if so, what level of credibility can be applied to the results of the com-
parisons by computer. If, beyond these objectives, the analysis throws any new light
on probable phylogenetic relationships above the level of families, then the exercise
will be extended with a view to increasing the level of acceptability of results.

INVESTIGATION WITH THE AID OF COMPUTER PROGRAMS

The first stepinthe present exercise wasto study the methods of numerical taxonomy
as expounded by Sokal & Sneath (1963). Difficulties were encountered regarding the
methods of dealing with multi-state characters; generally speaking, where there were
three or more answers to any one question it was not possible to arrange the answers
in a linear series and assign a hierarchical series of values to the various alternative
answers. Even where this would have been possible, much important information would
have been lost by the subsequent process of determining the mean of all the answers
to a given question and grouping all those answers below the mean on the one hand,
and all those answers above the mean on the other hand. Even if this procedure had
been desirable on analytical grounds, which it was not, it would have been quite im-
practicable for the present exercise; it would have necessitated re-calculating means
for all questions whenever a few more genera were added to the survey before the
coefficients of similarity of these genera could be assessed. The procedure adopted
for multi-state characters was to treat each answer to a given question as being
distinct from all other possible answers to that question. When comparing any two
genera with a view to assessing the coefficient of similarity, for each question posed

PURCHON and BROWN 167

the animals are either identical or they are different. By the adoption of this pro-
cedure no information is lost, and no preliminary assumptions (e.g., as to affinities
between filibranchs and pseudolamellibranchs, between pseudolamellibranchs and
eulamellibranchs,) are made.

In the present exercise all criteria are held to be equally relevant, and none is
weighted. The only limit to the questions employed has been availability of information.
The questions have not been confined to comparative anatomy, but have ranged over
geographic distribution, ecological preferences, behaviour, physiology, etc. Itis
appreciated that excessive attention to one organ system might bias the results, but
it is thought better to use all the available information rather than to omit some in-
formation (necessarily on subjective grounds) in order to balance the information
obtained from contrasted sources. The purpose ofthe exercise is to obtain the largest
possible random sample of information relating to the genetical constitution of each
genus investigated. As many different answers were drafted as were required to record
objectively the different conditions observed. It follows that as the investigation
extends to cover more genera, the number of possible answers to any one question
will gradually increase. Since each answer is regarded as distinct from all other pos-
sible answers, no difficulty is encountered with regard to those genera which have
already been processed. Atthe present time 27 genera have been subjected to scrutiny,
and the questionnaire includes 96 questions. 49 of these questions have 2 alternative
answers, 20 have 3 alternative answers, 5 have 4 alternative answers, 11 have 5
alternative answers, 7 have 6 alternative answers, while 1 each have 7, 8, 9 and 11
alternative answers. Inallthere wasatotal of 310 possible answers to the 96 questions
posed.

For each genus certain questions were logically barred, and these were not used;
thus for septibranchs it was not possible to answer questions concerning the structure
and ciliation of the ctenidial lamellae. For each genus a few questions could not be
answered due to lack of available information. This paper is confined to considera-
tion of 27 genera for which a very high proportion of answers was obtained. When
comparing any two genera two statistics were available: 1) the total number of
questions for which answers were obtained for both genera, 2) the number of questions
for which the same answer was obtained for both genera. The latter was expressed
as the percentage of the former, this figure providing a measure of the coefficient of
Similarity of the two genera. Thus Barnea and Martesia, both members of the family
Pholadidae showed a coefficient of similarity of 82.4%, while Tellina and Egeria which
are members of different families in the order Tellinacea showed a coefficient of
similarity of 82.7%.

The organisation of the computer program was as follows: The data, comprising
the coded answers to the questionnaire, were read for each genus under investiga-
tion and stored internally. Each genus was then compared with every other genus
under investigation and the two statistics, 1 and 2 defined above, were calculated and
stored. The second phase was the production of the results in such a way that a dendro-
gram could easily be constructed. At each step one genus was combined with a
second genus, or with a group of genera, the choice being made so that the coefficient
of similarity was the highest of all the possible pairings, whereupon the identifying
codes for the cluster of genera were output together with the calculated coefficient.
One of the pair was deleted from further consideration, and its two statistics added
to the corresponding quantities for the second group, the group thus newly formed being
identified by the higher of the code numbers of its two constituents. In this way the
total number of groups was reduced by one, and the process was repeated until only
one group remained. The dendrogram so produced is shown in Figure 2.

Inspection of Fig. 2 shows that analysis of data by computer corresponds closely

168 PROC. THIRD EUROP. MALAC. CONGR.

at many points with the traditional views on the phylogenetic groupings of genera.
This is in spite of the random nature of the information used, and the inclusion of
many data hitherto regarded as irrelevant to any discussion on phylogeny; e.g., the
grouping of the erycinaceans, Kellia, Montacuta and Газаеа; e.g., the grouping of the
tellinaceans, Tellina and Egeria; e.g., the grouping of the protobranchs Nucula and
Nuculana; e.g., the grouping of Arca similis and Anadara granosa with Glycymeris.
The most striking cluster, however, is that of the rock- and wood-boring pholads,
Barnea and Martesia with Xylophaga and with the shipworm, Teredo.

It is clear that if the exercise were extended to cover many more genera, there would
be substantial changes in the lowermost part of the dendrogram; we should not take
too seriously the suggested groupings for Ensis, Astarte and Brechites (dotted lines),
or for Petricola, Tridacna, Cuspidaria, Pinna and Pecten (broken lines). It seems
necessary, therefore, to adopt a “level of credibility” for such a dendrogram, below
which the associations suggested should not be regarded as trustworthy. In this case
the highly orthodox results for the rock- and wood-boring genera in the Pholadidae
and Teredinidae suggest that the “level of credibility” of the dendrogram should be
set at 74.0%.

It is hoped that extension of the survey to cover many more genera will provide
good grounds for setting the level of credibility at a considerably lower level, and that
the procedure will accordingly become capable of throwing light on successively higher
taxonomic groupings. For the present, however, it is safest to confine our attention
to clusterings above the 74% level.

Sokal € Sneath (1963) emphasise that numerical taxonomy is incapable of establishing
phylogenetic relationships, but only coefficients of similarity; close phylogenetic
relationship may be obscured by strongly divergent evolution, while convergent evolu-
tion may suggest a closer phyletic relationshipthanis true. At the same time, however,
Sokal & Sneath agree that convergent evolution will seldom completely obscure the
fundamental differences between only distantly related lineages. It seems probable,
therefore, that a high coefficient of similarity will generally truthfully indicate a close
phyletic affinity. On these grounds it seems possible to consider the clusters above
the 74% level in Fig. 1 as being indicative of possible phylogenetic relationship. This
view is firmly upheld by the details of clustering of the genera Barnea, Martesia,
Xylophaga and Teredo, of the genera Tellina and Egeria, of the genera Nuculana and
Nucula, of the genera Arca, Anadara and Glycymeris, and of the genera Kellia,
Montacuta, Lasaea and Turtonia. The systematic position of Turtonza has been dis-
cussed by Oldfield (1955) and by Ockelmann (1964); Turtonia is considered to be a
neotenous veneracean by Ockelmann, and it is unfortunate that, having been unable to
include any member of the Veneridae in the investigation, it has not been possible
to put Ockelmann’s views to the test.

The clustering of Cardium, Glossus, and Chama is interesting, and more detailed
investigations of possible affinity between these genera is desirable; Cardium and
Glossus are both rather tumid members of the superficial in-fauna of sedimentary
deposits, while Chama is attached by cementation to the surface of rocks. The most
striking feature of the exercise is the clustering of Dreissena and Mytilus, at a co-
efficient of similarity of 76.8% The generally accepted view, which has recently
been re-stated by Yonge € Campbell (1968) is that the eulamellibranch Dreissena
is unrelated to the filibranch Mytilus, and that resemblance between these two
genera is due to the adoption of a similar mode of life, and to convergence. The
present exercise reveals that the similarities between Dreissena and Mytilus far
outweigh the differences numerically. Should the features of dissimilarity be so heavily
weighted that convergent evolution is deemed to be more probable than descent from
a common ancestor? If convergence has occurred between these two genera, what is
the statistical probability of the achievement of so high a coefficient of similarity?

PURCHON and BROWN 169

We revert once more to the work of Ridewood (1903) who showed that in four families
one or two species had advanced beyond the remainder in ctenidial structure. Is it
not probable that Dreissena is another such example, which evolved from the fili-
branch to the eulamellibranch state? Dreissena has advanced in other respects,
notably in the fusion of left and right mantle lobes with the production of inhalant and
exhalant siphons. There can be по doubt that Dreissena is not a mytilid, but if we do
not allow ourselves to be over-impressed with its eulamellibranch status, we might
eventually concede that Dreissena may have evolved directly from a mytilid ancestry,
and may exhibit closer phyletic relationship with the Mytilidae than with any family
in the Eulamellibranchia.

DISCUSSION

We have first to consider to what errors the adopted procedure may be susceptible.
Firstly, it is probable that the results of the investigation will be influenced to some
extent by the proportions in which information is contributed from different organ
systems, etc. Thus a great increase in knowledge of the physiology of digestion, for
example, would be expected to cause some changes in the coefficients of similarity
and in the dendrogram. Ideally, therefore, the quantities of data from contrasted
sources should be well balanced, and the data as a whole should provide a random
sample of information on the gene complexes of the genera studied. We cannot claim
that the questionnaire used in this exercise is ideally balanced, but this cannot be
rectified by subjective suppression of information on our part. The information utilised
is certainly random, in that it has not been selected, and it is hoped that the results
of the exercise will, at least, supply some useful indications.

A second likely source of error in a simple system such as that employed here, is
the possible occurrence of instability, i.e., of obtaining different results if the data
are presented to the computer in a different order. To obviate this risk one of us
(D.B.) ran the program with the whole of the 27 sets of data presented in about 55
different orders, identical results being obtained in each case.

Extension of the survey to include many more genera would introduce many more
primary clusters, and this would probably change the lowermost parts of the dendro-
gram. To meet this undeniable criticism the dendrogram has been drafted appropri-
ately, and only those clusters set in continuous lines merit serious consideration at
the present time; broken lines indicate possible associations, the details of which are
subject to adjustment after consideration of many more genera; the dotted lines have
little or no significance, and should be disregarded.

After these precautionary remarks, the first and most important question to be
answered is whether the information provided by computer analysis of this large body
of data is meaningful in terms of phylogenetic relationships at and above the level of
families? If so, what is the lower limit of credibility for the results (dendrogram in
Fig. 2)? It is encouraging to find that to a considerable extent the results of the in-
vestigation endorse the wisdom of earlier malacologists who did not have the advantage
of such extensive biological information, or the opportunity to analyse extensive data
by computer. The coefficients of similarity reportedfor Barnea, Martesia, Xylophaga
and Teredo are highly orthodox in their implications on the affinities of these genera;
this suggests that a level of credibility might well be set as low as 74% in Fig. 2,
and that all clusterings above this level are worthy of serious consideration. Most
of these clusters are, in fact, generally acceptabie, and do not call for further dis-
cussion. Further consideration should be given to the cluster: Cardium / Glossus /
Chama, and to the cluster: Dreissena / Mytilus. It is not our present intention,
however, to pursue such matters of detail; our purpose is to determine whether the

170 PROC. THIRD EUROP. MALAC. CONGR.

procedure adopted is capable of supplying meaningful indications of phyletic relation-
ship, and it appears to us that the results of the exercise are very encouraging.

As the clustering process advances there is a steady decrease in the number of
questions which receive identical answers from all genera in the cluster; conversely
there is a steady increase in the number of questions the answers to which vary from
one genus to another within the cluster. It has been contended that this increase may
interfere with the efficiency of the clustering process. We do not think that this is a
serious issue, but it would be possible to test the question by interrupting the course of
the program at, say 5% intervals, and deleting such questions as have ceased to pro-
vide consistent answers within the individual clusters. It has been conventional to
disregard, for phyletic considerations, any character which shows variability within
the genus or within the family, e.g., hermaphroditism, which occurs sporadically in
many lineages. Such characters areclearly uselessas major criteria for sub-division
of the class, yet they may be of considerable importance in an exercise in numerical
taxonomy. Thus hermaphroditism, though sporadic in many lineages, seems to be
characteristic of the Anatinacea. Accordingly, it is doubtful whether it would be
desirable to exclude such variable characters from the program in an attempt to make
the later stages of clustering more accurate. Apart from any question of progressive
amendments of the data in order to delete questions and answers which have no
relevance to later parts of the clustering process, it would be highly desirable to ana-
lyse the data for a different purpose; namely to ascertain which questions and answers
are of prime importance for systematic purposes. It would be of the greatest value
to obtain by such objective methods an acceptable decision as to “which characters
are of real taxonomic value ... ” (Cox, 1960)!

A further point of importance which may emerge from the analysis of extensive
data by computer programs concerns the coefficients of similarity which generally
indicate differences between phylogenies at generic, at familial, or at ordinal level.
The information at present available is inadequate for this purpose; thus Barnea and
Martesia, both members of the family Pholadidae, have a coefficient of similarity of
82.4%, while an almost identical coefficient (82.7%) is shown by Tellina (family Tel-
linidae) and Egeria (family Donacidae) which are both members of the order Tellinacea.
The levels at which taxonomic terms such as genus, family, order, etc., can best be
applied will naturally vary somewhat from one phylogeny to another - partly, perhaps,
according to the number of generaineach phylogeny and partly according to the degree
of structural adaptation to habitat and to mode of life. One would not wish to impose
any strict regularity in the use of such terms, but the existence of a more extensive
dendrogram than that presented here (Fig. 2) would probably assist by indicating the
occasional need for intermediate terms such as super-family or sub-order.

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RIDEWOOD, У. G., 1903, On the structure of the gills of lamellibranchs. Phil.
Trans. B, 194: 147-284.

SOKAL, R. R. & SNEATH, P. H. A., 1963, Principles of Numerical Taxonomy.
Freeman, London.

THIELE, J., 1935, Handbuch der systematischen Weichtierkunde.3 Teil. Fischer, ena.

YONGE, С. M., 1959, The status of the Protobranchia in the bivalve Mollusca.
Proc. malac. Soc. Lond., 33: 210-214.

YONGE, С. М. & CAMPBELL, J. Т., 1968, Оп the heteromyarian condition in the
Bivalvia with special reference to Dreissena polymorpha and certain Mytilacea.
Trans. roy. Soc. Edinb., 68: 21-43.

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MALACOLOGIA, 1969, 9(1): 173-177
PROC. THIRD EUROP. MALAC. CONGR.
ON THE TAXONOMY AND BIOGEOGRAPHY OF HYDROBIIDAE
Pavle Radoman
Faculty of Science, Beograd, Yugoslavia

In examining the gastropod family Hydrobiidae, in particular its representatives
from Lake Ohrid and from waters of Dinaric karst (Yugoslavia), I noticed many errors
in taxonomy, which is based mainly on the shell. For that reason I did not consider
their present taxonomy to be reliable.

Two groups of errors are to be found here. On the one hand, the anatomically
different species are included in the same genus because of their similar shells; in
some cases species from different families, even from different subclasses, are
included in the same genus. On the other hand, the anatomically similar species are
separated into different genera (in some cases in different subfamilies) owing to
their conchological differences.

Some examples of these errors follow: Bythinella robiciClessin (1887) anatomically
is а Sadleriana (Radoman, 1965) (Fig. 1), Sadleriana virescens Küster (1852) is a
Pseudamnicola, Sadleriana macedonica Kuséer (1936) is a Нотайа (Radoman, 1966a),
Pseudamnicola consociella Wagner (1927) is a Hydrobia (Radoman, 1966a) (Fig. 2),
Lithoglyphus notatus Frfld (1865) is а Pseudamnicola (Radoman, 1966a), Lithoglyphus
pygmaeus Fríld (1863) is а Sadleriana (Radoman, 1966b), Valvata ohridana Polinski
(1929, 1932), later determined as a Horatia (Komarek, 1953) in fact is a Pseudohoratia
(Radoman, 1967b), Gocea ohridana HadziSée (1956) determined as a representative of
Hydrobiidae, is a species of Valvatidae (Radoman, 1962), and, finally, a non-hydrobiid
example, Gyraulus relictus Polinski (1929) (Pulmonata) is a Valvata (Radoman, 1955).

Some examples of the second group of errors are: Hydrobia prespensis Urbanski
(1939) (syn. Micromelania prespensis HadziSée, 1953), Hydrobia grochmalickii Polinski
(1929) (syn. Pyrgohydrobia grochmalickii Radoman, 1955) and Diana thiesseana
(Godet) Kobelt (1878) all belong to the same genus, Diana (Fig. 3); anatomically they
are quite similar. Pyrgula sturanyi and Neofossarulus stankovici (from Lake Ohrid)
both are representatives of the genus Chilopyrgula (Radoman, 1955). The Lake
Ohrid species ornata I determined to be a Pseudamnicola оп the basis of its anatomy
(Radoman, 1956); but on the basis of its shell it was determined by HadziSée (1956) as
a new genus, Ohrigocea.

On the basis of shell similarities 5 species were erroneously included in the genus
Pseudamnicola (Radoman, 1966a), 5 in Нотайа (Radoman, 1966a) and 9 in Lithoglyphus
(Radoman, 1966b).

These and several other examples of taxonomic errors should not be considered
exclusively subjective ones, but they are often conditioned by the objective unsuit-
ability of the shell as an exclusive taxonomic character.

The taxonomic importance of the radula (especially when regarding genus deter-
mination) is not greater than that of the shell. For instance, radulae in Pyrgulinae
and Micromelaniinae are similar in spite of different anatomies of these 2 groups.
The nervous system, if considered independently from other characters, also cannot
always show relationships of the genera. For example, the nervous systems are
quite similar in Hydrobia and Pyrgula, genera of 2 different subfamilies.

The examples mentioned above, and many others, show that systematics based on
one single character can cause numerous errors. Nevertheless, it is possible to find

(173)

174 PROC. THIRD EUROP. MALAC. CONGR.

FIG. 1. Bythinella, Sadleriana robici, Sadleriana fluminensis

FIG. 3. Diana prespensis, D. grochmalickii, D. thiesseana.

RADOMAN 175

a single character that is suitable for classifying species, genera and other taxa, but
such a character should be used only in conjunction with other characters. According
to my experience with the family Hydrobiidae, sucha character is the genital systems,
especially that of the female.

The following examples show, however, that in different genera the anatomy of some
systems of organs cannot always be similarly correlated. According to an analysis
of the constitution of female reproductive organs and of the nervous systems, the
genera Emmericia and Lithoglyphus are so similar that they cannot be distinguished.
However, the differences between the 2 in the anatomy of accessory parts of the male
reproductive organs are quite obvious, making it possible to distinguish these 2
genera (Radoman, 1966b, 1967a). On the other hand, the anatomical characters of the
nervous systems and of the male reproductive organs would not enable one to dis-
tinguish the genera Hydrobia and Pyrgula, which, however, are clearly distinctive
according to the reproductive apparatus of their females (Radoman, 1955a, 1955b).
Many further examples can be cited which show that phylogenetic relationships can be
determined only after considering a number of different anatomical characteristics.
This does not meanthat shell-morphology has noimportance in taxonomical determina-
tions: it must be taken in account when distinguishing different species of the same
genus which have basically the same anatomical characteristics. In the taxonomic
determination of higher groups, beginning with the genus, shell morphology should be
used only in a correlation with anatomical characteristics. Otherwise, the errors
mentioned above are unavoidable.

I consider that correct generic diagnoses are of cardinal importance for a reliable
assessment of phylogenetic and taxonomic relationships in afamily as well as between
several families and other groups. Only by complex anatomical analyses was it pos-
sible to detect with certainty the differences among the Baicaliinae, Micromelaniinae
and Pyrgulinae, and to determine their genera and species (Koshov, 1951, Radoman,
in manuscript). However, the taxonomy of the Hydrobiinae is not yet clear (e.g., it
seems obvious that the genera Emmericia and Lithoglyphus should not be grouped with
the genus Hydrobia, or this genus allied to Pseudamnicola and Sadleriana).

In my anatomical examinations of Hydrobiidae I was able to see that the taxonomic
characters of genera are predominantly internal. This stimulated me to try to form
conchylio-anatomical diagnoses of several hydrobiid genera, i.e., diagnoses con-
taining both conchological and anatomical records. I have now succeeded in diagnosing
about 20 genera.

All this forces one to conclude that itis indispensable to give a conchylio-anatomical
diagnoses on the type species, quoting its exact type locality, before introducing a new
genus name. Additionally, in my opinion, good figures are more important, especially
for the main characters, than a verbal description, however extensive it might be. If
we omit to do so, further descriptions and classification of new species on the basis
of purely conchological genera diagnoses inevitably leads to the accumulation of new
errors, in addition to the numerous old ones, and to their unjustified “modernization. ”

As it is well known, a correct taxonomy, as a reflection of phylogenetic relations,
is of great importance for the establishment of biogeographical relationships between
small or large territories, and are important for explanations of speciation processes.
There are examples which illustrate a disharmony between at least a part of present
taxonomy and the geographical distribution of Hydrobiidae, and we can see to what ex-
tent a correction of taxonomical errors “purges” the erroneously conceived bio-
geographical picture.

To mention again the Baicaliinae, Micromelaniinae and Pyrgulinae, Thiele (1929)
placed several species from the United States, Japan, China, South Africa and Aus-
tralia, together with the north Italian Pyrgula annulata, in the hydrobiid subfamily

176 PROC. THIRD EUROP. MALAC. CONGR.

Truncatellinae. On the other hand, he included Diana from Greeceand other pyrgulid
forms from Lake Ohrid (Macedonia) in a separate family, Micromelaniidae. Polinski
(1929, 1932) included 2 species from Lake Ohrid (Micromelania filocincta and Stanko-
vicia baicaliiformis) in genera identical or related to those from the Caspian Sea (the
first species) or to those from Baical Lake (the latter), and pointed at the biogeo-
graphical relations of these water basins. Using the shell, sometimes the radula,
Thiele (1929) included the genera Baicalia and Micromelania in the same subfamily,
while Kozhov (1951), considering their anatomies, placedthese 2 genera into 2 families,
the first of which is confined to Baical and the second to Ponto-Caspian basin.

According to my anatomical examinations, there are norepresentatives of the Baical
and Caspian hydrobiid fauna in Lake Ohrid, the Ohrid hydrobiid fauna being related to
the endemic fauna of the Dinaric karst, or, more extensively, to that of Adriatic and
Aegean drainage areas. The representatives of the group Pyrgulinae are spread from
Lake Garda in Italy, through the Adriatic (Dalmatic) littoral zone (Pyrgula annulata
in Garda, Zrmanja River, Lake BaCina, in some tributaries of Neretva, and in Lake
Scutari), in Lake Ohrid (endemic genera: Chilopyrgula, Ochridopyrgula, Micropyrgula,
Stankovicia, Trachyochridia, Ginaia), in Lake Prespa(Diana prespensis)and in 2 Greek
lakes: Lake Trichonia (Diana thiesseana) and Lake Amvrakia (D. schlikumi). From
the malacological literature, some representatives of the Pyrgulinae are also reported
for Turkey and Israel, but it is necessary to prove this distribution from anatomical
inspection of the species. !

An anatomical examination is also necessary in the case of some alleged repre-
sentatives of this subfamily in southern France, e.g., Р. pyrenaica Bourg. and P.
darieuxi Fol. € Beril. The Pyrgulinae is mainly an Adriatic-Aegean group, which is
taxonomically and biogeographically different from the subfamilies Baicaliinae and
Micromelaniinae.

LITERATURE CITED

CLESSIN, S., 1887, Molluskenfauna Osterreich-Ungarns. Nürnberg, Bauer € Raspe,
860 p.

HADZISCE, S., 1953, Prilog poznavanju gastropoda Prespanskog i Ohridskog jezera.
Glasnik bioloëke sekcije, Zagreb, Ser. П/В, T. 7: 174-177.

HADZISCE, S., 1956, Beitrag zur Kenntnis der Gastropodenfauna des Ohridsees. III.
Recueil des travaux, Ohrid, IV, 1(14): 57-107.

KOBELT, E., 1878, Diagnosen neuer Arten. Jahrb. dtsch. Mal. Ges., B.V: 319-321.

КОМАВЕК, J., 1953, Herkunft der Sússwasser-Endemiten der dinarischen Gebirge...
Arch. f. Hydrobiologie, Stuttgart, 48, 3: 269-349.

KOSHOV, М. M., 1951, К morfologii i istorii Bajkalskih endemiényh molljuskov sem.
Baicaliidae. AN SSSR Trudy Bajkalskoj limnologiceskoj stancii, XIII: 93-119.

KUSTER, H. C., 1852, Die Gattungen Paludina, Hydrocaena und Valvata. In: Martini
€ Chemnitz, Syst. Conch. Cab., I, 21: 1-96, Nürnberg (Bauer € Raspe).

KUSCER, I. J., 1936, Zur Kenntnis der Molluskenfauna von Súdserbien und Montenegro.
Bull. Soc. sci. Skopje, 17(5): 101-104.

POLINSKI, V., 1932, Die reliktáre Gastropodenfauna des Ochrida-Sees. Zool. Jb.
Syst., 62: 611-666.

RADOMAN, P., 1955a, MorfoloSko-sistematska istraZivanja ohridskih hidrobida.
Srpsko biolosko druëtvo. Pos. izd. 1, 106 р, Beograd.

| Meanwhile, from Hartwig Schütt I received specimens of Chilopyrgula zilchi (Schütt, 1964, Arch. f. Mollk.
93, 5/6), and established that this form, conchologically similar to Pyrgula, anatomically could not be
included in the Pyrgulinae. The results of this examination will be published soon.

RADOMAN 177

RADOMAN, P., 1955b, Prilog poznavanju gastropoda ohridskog basena. Recueil des
Travaux, Ohrid, III, 2(12): 23-39.

RADOMAN, P., 1956, Nove ohridske hidrobide. Arh. biolo3kih nauka, Beograd,
VIII(1/2): 87-92.

RADOMAN, P., 1962, Nove ohridske hidrobide (II). Arh. bioloskih nauka, Beograd,
XIV(1/2): 69-93.

RADOMAN, P., 1965, Das Genus Sadleriana. Glasnik Prirodnjackog Muzeja, Beograd,
B20: 121-126.

RADOMAN, P., 1966a, Die Gattungen Pseudamnicola and Horatia. Arch. Moll.,
Frankfurt, 95(5/6): 243-253.

RADOMAN, P., 1966b, The zoogeographical and phylogenetic interrelations of the
genera Lithoglyphus and Emmericia. Glasnik Privodnjackog Muzeja, Beograd,
B21: 43-49.

RADOMAN, P., 1967a, Speciation of the genus Emmericia (Gastropoda) оп the Adriatic
area. Basteria, 31(1/3): 27-43.

RADOMAN, P., 1967b, Revision der Systematik einiger Hydrobiidenarten aus dem
Ohrid See. Arch. Moll., Frankfurt, 96(3/6): 149-154.

RADOMAN, P., Pyrgulinae, eine Unterfamilie der Hydrobiidae. Im Manuskript.

THIELE, J., 1929/31. Handbuch der systematischen Weichtierkunde. I. Gustav
Fischer, Jena, 778 p.

URBANSKI, J, 1939, Über drei neue Schneckenarten aus dem südlichen Teile Jugo-
slaviens. Zool. Pol., 3: 260-266.

WAGNER, A., 1927, Studien zur Molluskenfauna der Balkanhalbinsel... Ann. Zool.
Mus. Polen. Hist. nat., 6(4): 263-301.

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MALACOLOGIA, 1969, 9(1): 179-185
PROC. THIRD EUROP. MALAC. CONGR.

THE USE OF THE SCANNING ELECTRON MICROSCOPE IN
THE STUDY OF THE GASTROPOD RADULA: THE RADULAE
OF AGRIOLIMAX RETICULATUS AND NUCELLA LAPILLUS

N. W. Runham

University College of North Wales, Bangor,
Caernarvonshire, Wales, U. K.

INTRODUCTION

Recent studies have shown that the scanning electron microscope with its very great
depth of focus even at high magnifications allows us for the first time to examine the
detailed three dimensional morphology of the smaller radular teeth (Runham &
Thornton, 1967; Thompson & Hinton, 1968). The patterns of wear seen on the teeth
also make it possible to deduce the orientation of the teeth during feeding (Runham
& Thornton, 1967). For these morphological studies the radula was removed from
the animal, cleaned, laid flat on a brass stub, and then air-dried. In life the radula
covers the odontophore cartilages which usually have the form of a U-shaped gutter.
Therefore, in order to obtain detailed information on how the teeth are used during
feeding it is essential to examine the radula while it is still covering the underlying
cartilage. Studies of this kind have been made on the grey field slug Agriolimax
reticulatus and on the dog-whelk Nucella lapillus and are reported here.

MATERIALS AND METHODS

Agriolimax veticulatus and Nucella lapillus were collected locally. The animals
were allowed to crawl and then beheaded with a sharp scalpel. The dorsal skin of the
head was completely removed so as to exposethe buccal mass. Removal of the dorsal
wall of the buccal mass exposed the odontophore (consisting of the radula, odontophore
cartilages and associated muscles) inthe buccal cavity. The exposed part of the radula
which covers the anterior surface of the odontophore was then washed repeatedly
with saline to remove mucus and any food particles. The lateral and ventral walls of
the head were then dissected away very carefully so as to cause as little disturbance
as possible to the musculature of the buccal mass. The isolated buccal mass was
laid on a weak gelatin gel which coated the surface of a brass stub; it was rapidly
frozen by plunging into liquid nitrogen, and thenfreeze dried at -60° C in a Speedivac-
Pearse Tissue Drier (Edwards High Vacuum Ltd.). When dry the stub was removed
and placed in a vacuum coating unit wherethe buccal mass was coated with an approxi-
mately 400 Ä thick layer of gold which was applied in two stages, firstly from above
and then from the side while the stub was slowly rotated in both cases. This pro-
cedure was essential in order to get the specimen evenly coated. The buccal mass
was examined in a Cambridge Stereoscan Scanning electron microscope.

THE RADULA OF AGRIOLIMAX RETICULATUS

The morphology of the teeth has been described in detail elsewhere (Runham &
Thornton, 1967) and so will not be given in detail here. Each transverse row of the
radula consists of a symmetrical central tooth and on each side of this are a number
of lateral teeth (approximately 20) andthese areflanked by the marginal teeth (approxi-
mately 20). The distinction between these teethcan clearly be seen in Fig. 1.

(179)

180 PROC. THIRD EUROP. MALAC. CONGR.

FIG. 1. Agriolimax reticulatus. Lateral view of the odontophore tip. Note the dorsal groove
(G).

The radula is secreted by the radular gland which lies in the gutter formed by the
cartilages and projects from its posterior end. New teeth are added to the radula at
its posterior end and at 20°C they move forwards at a rate of 5 rows a day (Isarankura
& Runham, 1968). Within the gland the radula is curled up at its lateral edges so that
in transverse section the radula forms an almost complete ring with the central teeth
occupying the mid-ventral position and the outermost marginal teeth from the two
sides almost touching dorsally. Within the radular gland all the teeth point inwards.
Towards the anterior end of the radulathe secretary epithelium above the teeth breaks
down and is succeeded by an epithelium having a thick cuticle, the collostyle hood
(Runham, 1963). As the radula moves forward out of the radular gland (Fig. 4) the
teeth are exposed. This newly emerged radula still lies in the u-shaped gutter formed
by the odontophore cartilages, the radula lining the walls of the gutter and the teeth
projecting into it. The collostyle hood forms a vertical wall marking the posterior
limit of the dorsal groove in the odontophore (Fig. 4). There is a pattern of markings

RUNHAM 181

И
АИ
| or

FIG. 2. A. reticulatus. Anterior edge of FIG. 3. A. reticulatus. The surface of the
the radula and the buccal cuticle (B). Note the buccal cuticle next to the anterior edge of the
blocks of worn teeth detaching at the edge. radula.

on the surface of the collostyle hood cuticle of approximately the same width as the
teeth. It is not known ifthese markings arise during formation of the cuticle or during
use of the radula.

At their anterior end the odontophore cartilages taper to form a conical tip with a
dorsal groove. The anterior endof the radula is reflected over the edges of the groove
and backwards over the conical tip of the cartilages (Fig. 1). At the extreme an-
terior edge of the radula worn teeth drop off and are usually swallowed (Isarankura
& Runham, 1968). The detachment of blocks of these teeth can be seen in Fig. 2. As
this detachment is only seen along this anterior edge of the radula and not along the
lateral edges it is unlikely that it is an artefact due to drying. The buccal cuticle
near to this detachment area has characteristic markings which may represent
scars of the old teeth.

During feeding the mouth is opened and the 'odontophore is brought forward and
downward to meet the substrate. When first applied to the substrate the tip of the
odontophore is at its most posterior position. The cartilage is then rotated so that
the tip moves rapidly forward to its most anterior position when it is withdrawn into
the buccal cavity. The odontophore carries out a series of these “licking” move-
ments. It has been shown very clearly in many other molluscs, from an analysis of
feeding tracks (Markel, 1958, 1967), that while the odontophore is moving in this way
so the radula is also moving over the cartilages. The speed at which the teeth rasp
the substrate is the sum of the speed of the feeding stroke of the odontophore plus
the speed of movement of the radula over the cartilage. When the odontophore is in
its most posterior position at the start of the feeding stroke the radula is pulled out
of the groove in the cartilages to its greatest extent, and when it has reached its most
anterior position the radula has been pulled back into the groove to its greatest ex-
tent. As the radula moves out of the gutter over the edge of the cartilage and on to
the surface of the cartilage and vice versa so the orientation of the teeth changes.

182

PROC. THIRD EUROP. MALAC. CONGR.

Latero-dorsal view of the groove in the odontophore. Note the collo-

FIG. 4. A. reticulatus.
style hood (C) and the newly emerged teeth (T).

# #

HH TE y

e gn" Ff

À. =

2299

FIG. 5. A. reticulatus. Dorsal view of the odontophore shown in Figure 1. 2 longitudinal
rows of lateral teeth and 5 rows of marginal teeth are marked. The numbers and letters are ex-

plained in the text.

RUNHAM 183

FIG. 6. Nucella lapillus. Anterior view of the odontophore tip. The letters are explained in
the text.

The orientation of the teeth depends upon their position on the cartilage and this de-
pends in turn on the particular stage of the radula movement cycle. From an ex-
amination of the tip of the odontophore at any stage of the cycle and a study of the
orientation of the teeth in successive rows the change in orientation of any one tooth
during the cycle can be deduced.

An analysis of the orientation of lateral teeth using photographs taken at several
magnifications and from several angles (e.g., Fig. 5), shows that as they move over
the edge of the cartilage the teeth rotate through approximately 125°. With reference
to Fig. 5, tooth 1 is moving forwards to the edge of the cartilage with its cusps well
exposed since the tooth in position 2 has rotated upwards. Taking tooth 1 as a base
line, tooth 2 has rotated through 35°, 3 has rotated through 75°, 4 through 119%
and 5 through 125°. Thus if the teeth cusps at position 1 penetrate food material it
will be lifted up and then dragged towards the groove. This type of movement may
result in the tearing off of chunks of food, in contrast to the removal of small pieces
by the rasping of teeth on the outside of the odontophore. Examination of the crop

184 PROC. THIRD EUROP. MALAC. CONGR.

FIG. 7. N. lapillus. Ventral view of the odontophore shown in Figure 6. Note that the teeth
are extremely worn.

following a meal reveals a mixture of large and small pieces (Walker personal com-
munication). The marginal teeth on the outside of the odontophore have the narrow
cusp erect (Fig. 5A) but as the teeth pass back over the lateral walls of the groove
they swing downwards into the groove (Fig. 5 BCD). It is unlikely that such tall cusps
would be used for rasping, but the downward movement of the cusps would hold material
against the lateral teeth and assist in the tearing off of large pieces and their
transport.

THE RADULA OF NUCELLA LAPILLUS

Although the buccal mass of Nucella lapillus is at the end of a long proboscis it
is anatomically similar to that of Agriolimax. The cartilage and radula are however
very narrow and each transverse row of teeth consists of only a central tooth and a
Single lateral tooth on each side. The detailed morphology of the teeth will be de-
scribed elsewhere, but it should be noted that the central teeth have three large heavy
cusps and the laterals have an inwardly curved very narrow cusp on the outer side of
the tooth. As shown in Fig. 7, the central teeth are worn while the lateral teeth in the
same row are less worn. Мисе Па feeds on bivalves and barnacles (Largen, 1967) using
the radula together with the accessory boring organ (Fretter & Graham, 1962) to bore
a hole through the shell, and then it consumes the tissues. It is likely from the shape
and wear of the central tooth that this tooth is used for boring. There is extensive
rotation of the central teeth as they pass over the tip of the cartilages (Fig. 6). The
lateral teeth on the convex outer surface of the odontophore have the cusps directed
away from the central teeth. As these teeth pass backwards over the odontophore
tip, however, the hook-shaped cusp rotates inwards and downwards between the back-
ward pointing central teeth (Fig. 6 ABC). The movement and shape of these lateral
teeth must result in the radula gaining a very efficient hold on soft tissue and in con-
junction with the retraction of the buccal mass will result in the tearing off of pieces

RUNHAM 185

of tissue. A rasping mode of feeding would presumably not be very effective for the
removal of soft tissue.

CONCLUSIONS

The scanning electron microscope in conjunction with freeze drying thus enables us
to examine the gastropod radula while itisin a similar position to that taken up during
feeding and can give us a better understanding of the functions of the teeth.

ACKNOWLEDGEMENTS

I am indebted to Dr. Thornton of the Electronic Engineering Department, U.C.N.W.,
Bangor, for help and advice with the scanning electron microscope, and to the SRC
for a grant.

REFERENCES

FRETTER, V., & GRAHAM, A., 1962, British Prosobranch Molluscs. Ray Society,
London.

ISARANKURA, К. & RUNHAM, М. W., 1968, Studies onthe replacement of the Gastropod
radula. Malacologia, 7(1): 71-91.

LARGEN, M. J., 1967, The diet of the dog-whelk, Nucella lapillus. J. Zool, Lond.,

151: 123-127.
MARKEL, K., 1958, Bau und Funktion der Pulmonaten-Radula. Z. wiss. Zool., 160:
213-289.

МАВКЕГ, К., 1967, Uber funktionelle Radulatypen bei Gastropoden unter besonderer
Berücksichtigung der Rhipidöglossa. Vie et Milieu, 17: 1121-1138.

RUNHAM, М. W., 1963, A study of the replacement mechanism of the pulmonate radula.
©. Jl. microsc. Sci., 104: 271-277.

RUNHAM, N. W. & THORNTON, P.R., 1967, Mechanical wear of the gastropod radula:
a scanning electron microscope study. J. Zool., Lond., 153: 445-452.

THOMPSON, T. E. & HINTON, H. E., 1968, Stereoscan electron microscope observa-
tions on opisthobranch radulae and shell structure. Bijdragen Tot de Dierkunde,
38: 91-96.

Sa tri TR Ry MS NA
at donne

DA | AÑ er AIDA

MALACOLOGIA, 1969, 9(1): 187-189
PROC. THIRD EUROP. MALAC. CONGR.

DOMINANCE BIOLOGIQUE DE QUELQUES MOLLUSQUES
DANS LES ATOLLS FERMES (TUAMOTU, POLYNESIE);
Phénomène récent - Conséquences actuelles

B. Salvat

Laboratoire de Malacologie
Muséum National d'Histoire Naturelle de Paris, France

Il y a maintenant 5 600 ans, les actuels atolls des Tuamotu étaient des formations
récifales au raz de l’eau, sans parties émergées. Cette situation resta inchangée
pendant deux millénaires et demi, malgré une montée du niveau de la mer, car les
coraux se maintenaient а la surface par leur croissance en hauteur. Il y a 3 000 ans,
le niveau de la mer commença à baisser; la différence de niveau entre le début d’émer-
sion et l’actuel niveau est de trois шёгез.1

Il y a ainsi quelques trois millénaires (1 000 ans avant J.C.), l’émersion de la
couronne récifale de chacune de ces formations provoquait un isolement plus ou moins
complet des eaux contenues dans un lagon, enfonction de la continuité de cette couronne
récifale émergée, qui donnait sa physionomie à ce qu’est actuellement un atoll. Tous
les intermédiaires étaient créés entre un atoll ouvert, avec une ou plusieurs passes
assurant de larges échanges hydrologiques entre les eaux de 1’осёап et celles du lagon,
et un atoll fermé aux eaux intérieures confinées.

Cinq missions en Polynésie française de 1965 à 19682 nous ont permis d'étudier
onze atolls de type different du sud et de l’est de l’Archipel des Tuamotu (Mururoa,
Fangataufa, Réao, Turéia, Maturei Vavao, Marutea Sud, Pukarua, Pukapuka, Hao,
Vahitahi, Nukutavake)? L’ötude de la faune malacologique de chaque lagon permet
d’avancer les conclusions suivantes.

Chaque atoll fermé n'est caractérisé que par deux ou trois espéces malacologiques.
A la trés grande pauvreté en monbre d’espéces s’oppose une extréme richesse en
nombre d’individus des espéces propres aulagon. Il est important de noter que chacun
d’eux posséde sa “carte d’identité” malacologique, car aucun n’est semblable a un
autre; celle-ci se définit spécifiquement et par l’importance numérique relative des
espéces entre elles.

Dans chaque atoll ouvert, la faune malacologique est riche en espéces, mais leurs
densités de peuplement sont extrêmement faibles. Toutes les espèces, qui peuvent
être récoltées dans tous les atolls fermés, se retrouvent sans exception dans un seul
atoll ouvert.

Cette opposition des richesses spécifiques d’une part et en densité de peuplement
d’autre part, de la faune malacologique, entre les atolls ouverts et les atolls fermés,
s'exprime également dans le cadre de l’ensemble des peuplements animaux de ces
lagons. Dans les atolls ouverts, les Mollusques n’occupent qu’une place tout à fait
négligeable dans le bios; les madréporaires sont largement prédominants. En revanche,
dans les atolls fermés, les Mollusques, par leurs incroyables densités de peuplement,
sont prépondérants, autant sinon plus que les coraux. On assiste à une importance

1LALOU (C.), LABEYRIE (Y.) et DELIBRIAS (G.). С. В. Acad. Sci. Paris, 263, série D, 1966, р. 1946.

2Conventions Muséum National d'Histoire Naturelle - Direction des Centres d’Expérimentations Nucléaires -
Service Mixte de Contrôle Biologique.

3Importance de la faune malacologique dans les atolls polynésiens. Cahiers du Pacifique, n* 11, p 7-49,
12 photographies, 7 figures.

(187)

188 PROC. THIRD EUROP. MALAC. CONGR.

croissante de la faune malacologique, en rapport avec l’isolement hydrodynamique du
lagon.

Les espéces, qui jouent ce röle déterminant dans les atolls fermés, sont au nombre
de quatre: Tridacna maxima, Pinctada maculata, Chama imbricata et Arca ventricosa.
Pour Tridacna maxima, la concentration maximale observée (100% du substrat;
Pukarua, Vahitahi, Réao, Turéia) est de 63individus au métre carré, soit une biomasse
en poids frais (valves exclues) de 4,9 kg. A Vahitahi, par exemple, dans un perimetre
du lagon d'une largeur de 2 métres (rivage) et d’une longueur de 39 mètres (perpendicu-
laire a la ligne de rivage), allant jusqu’ à la profondeur de 4 mètres (faciès a Acropora,
avec alternance de substrats meuble et dur), le nombre de bénitiers recensés est de
696, soit 90 000 à l'hectare (biomasse en poids frais - valves exclues - égale à 7
tonnes). Il est à noter que l’espèce est consommée par les habitants. Pour Pinctada
maculata, la concentration maximale (100% du substrat; Fangataufa) peut atteindre
350 à 400 individus au métre carré, soit une biomasse approximative en poids frais
de 1200 à 1400 g - valves exclues - mais la répartition des individus en paquets isolés
les uns des autres ne donne généralement qu’une densité de l’ordre de 100 à 150
individus au mètre carré.

L’abondance des bénitiers dans les atolls fermés doit être soulignée, car ceux-ci
contribuent dans une très large mesure au comblement du lagon. Reprenant les données
de l’exemple pré-cité, la densité des bénitiers correspond à 37 tonnes de valves à
l’hectare. Leurs valves, en s’accumulant, constituent des cordons lagunaires de
plusieurs métres d'épaisseur et de centaines de métres carrés de surface qui réduisent
la superficie du lagon, où la sédimentation est par ailleurs très importante. La faune
malacologique accélère ainsi les processus de comblement des lagons des atolls
fermés.

Nous avons tout lieu de penser qu’il y a 5 500 ans, alors que les atolls étaient
totalement immergés, la faune malacologique n’était guère plus abondante que
dans les atolls actuellement très ouverts. Il y a 3 000 ans, l’abaissement du
niveau de la mer a entraîné l’émersion des couronnes récifales créant des atolls
ouverts ou fermés. Le confinement des eaux des lagons a permis, dans les atolls
fermés, la multiplication, l'épanouissement et la prépondérance de quelques Mollusques,
pour d’évidentes raisons, entre autres, de moindre dispersion larvaire. C’est cette
explosion malacologique que nous observons aujourd’hui, 3000 ans après sa naissance,
dans ces atolls fermés, où les Mollusques contribuent inexorablement à leur perte
même, par complement du lagon jusqu’à sa disparition finale.

* * ko K K K K ok ok жж жж жж

Three thousand years ago the present Tuamotu atolls were fully submerged reefs.
Their present exposure results from a lowering of approximately three meters of the
ocean level. This accounts for the shape of present closed or open atolls as well as
intermediate forms, the morphology of such formations depending on the fact that
exchange between outer sea water and lagoon water does occur or not.

In open atolls the Mollusks display a great specific diversity together with a small
number of individuals (Mururoa, Hao). Оп the contrary in closed atolls a few species
are to be found along with a high number of individuals. (Réao, Turéia, Pukarua,
Vahitahi . . .). In open atolls Mollusks are of little importance in comparison with
the whole faunal community, while on the other hand they are a major feature of closed
atolls community (they may be as important ascorals and even more important).

Every closed lagoon could be identified through its molluscan specific fauna as well
as its relative abundance of species. Sessile Mollusks which can thrive in closed
atolls are few in species: Tridacna maxima, Pinctada maculata, Chama imbricata

SALVAT 189

and Arca ventricosa. Tridacna maxima may occur with heavy densities such аз 63
individuals per square meter which means a biomass of 4,9 kg live weight. Over a
lagoon side 2 m. wide and 39 m. long transect extending from the shore line down to
4 m. deep, an important population of Tridacna reached 696 individuals and was evalu-
ated as 7 tons of soft parts and 37 tons of shells per hectare.

Being heavily concentrated these Mollusks play an active part in the filling up of
lagoons. The important deposits of Tridacna shells are able to build up large lagunal
bar rubbles; these can attain several meters thickness and spread over several hun-
dred square meters.

Thus it can be concluded that three thousand years ago when the emergence of reef
formations took place, an extraordinary outburst of molluscan fauna occured in lagoons
of closed reefs. At the present time Mollusks are the prominent group of the whole
fauna and play an important part inthe land-building in the lagoons of these atolls.

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MALACOLOGIA, 1969, 9(1): 191-216
PROC. THIRD EUROP. MALAC. CONGR.

SOLENOGASTRES UND CAUDOFOVEATA (MOLLUSCA, ACULIFERA):
ORGANISATION UND PHYLOGENETISCHE BEDEUTUNG

Luitfried v. Salvini-Plawen
1. Zoologisches Institut

der Universitit Wien
Wien 1, Osterreich

INHALT
KUEZLAS UNG: er. a оборо соо E 191
1. Systematik und Organisation... . tr Net ee . 193

2. Phylogenetische Bedeutung einzelner Organe
(Muskulatur, Darmtrakt, Ernährung und Lokomotion

[Coelomfrage], Ctenidien, Larven) . . . ...... Е 199

3. Discussion . . . .. Mn RE с nus. Shake aed

Zusammenfassung/Summary . SD A Ол ПВА |

Iiteraturverzeichnis», ... ое о. нЕ 214
KURZFASSUNG

The organization of the aplacophoran molluscs has been greatly neglected in the
last 50 years, and the revision of these groups according to recent systematic principles
requires the separation of the Chaetodermatidae from the Solenogastres as an in-
dependent class Caudofoveata. The term ‘Aplacophora’ - which expresses only an
equal level of organization in both groups (in not yet having developed shell-like
structures) - therefore has to be dropped. Both classes, the Solenogastres (sensu
nomine) and the Caudofoveata, show significant phylogenetic relations in various
characteristics:

The existence of numerous serially-arranged pairs of dorsoventral muscular bundles
in Solenogastres and Caudofoveata represent the starting-point of a continuous sequence
of increasing concentration, which extends further over the Placophora (16 pairs of
bundles) and the Tryblidiacea (10-2 pairs) to the remaining Conchifera (8-0 pairs). A
comparison of these conditions with the situations of musculature and digestive tract
within the turbellarians consequently also demands a diverticulate intestine for the
original molluscs.

The testcell-larva of Solenogastres and Bivalvia-Protobranchia (partly as well as
these of Scaphopoda) must be placed at the very root of the molluscan stem and can
phylogenetically be considered a strongly fundamented type, for, due to its various
further relationships, the Trochophorae can easily be derived from the testcell-
larva (comp. DREW, CHANLEY). Supporting facts for these correlations include the
lack of protonephridia, the relatively late rectal anlage, and the caudal directed growth
of the nerve-cords out of the cerebral centre; while the development of protonephridia
and the local sinking of ganglious layers phylogenetically have taken place convergently
in more highly differentiated groups.

The adult nervous system, however, does not permit the use of the term ‘Amphi-
neura’, for neither Solenogastres nor Caudofoveata actually possess two separate pairs
of medullary cords, which is true on the other hand of the conchiferous Tryblidiacea.

Therefore, the Solenogastres and the Caudofoveata as well as the Placo-
phora, are consequently to be placed under the concept ACULIFERA (HATSCHEK,
1891), in contrast to the Conchifera. The organization of the Solenogastres and Caudo-
foveata demands in Summary greater notice and more intensive consideration.

In Betrachtung der Formenfülle der Mollusken ziehen auf Grund ihrer Quantität
zweifellos die Conchiferen das grössere Augenmerk auf sich (sodass vielfach nur sie
als Mollusca schlechthin betrachtet werden), doch vermögen kleine Splittergruppen oft
ein Gleiches an Qualität zu offenbaren. So stellen die in der Weichtierkunde seit langem
vernachlässigten aplacophoren Mollusken zwar eine nur geringe Formenzahl, doch

(191)

192 PROC. THIRD EUROP. MALAC. CONGR.

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АВВ. 1. Organisationsschema der Solenogastres. A. Vorderende, linke Körperwand abgetragen; В.
Querschnitt in der Körpermitte; C. Hinterende, linke Körperwand abgetragen. (aS, atriales Sinnesorgan;
Cd, Coelomoduct; Co, Copulationsstacheln mit Scheide; Dts, dorsoterminales Sinnesorgan; DV, Dorso-
ventral-Muskeln; Fd, Fussdrüsen; Fg, Flimmergrube; Gc, Cerebralganglion; Go, Gonade; Lg, Laichgang;
Md, Mitteldarm; Mf, Fussfurche mit Falten; Мб Mundöffnung; №1, laterales und NSv, ventrales Nerven-
system; Pc, Pericard; Pr, Pallialraum; Ra, Radula-Apparat; Sb, Samenblase (Recept. sem.); Sp, Spicula;

Vddr, Vorderdarmdrüsen).

SALVINI-PLAWEN 193

geben sie aber durch ihre Organisation begrtindeten Anlass mehr als bisher beachtet
zu werden.

1. SYSTEMATIK UND ORGANISATION

Im Anschluss an die Studien von WIREN (1892), ODHNER (1919), S. HOFFMAN (1949)
und ВОЕТТСЕВ (1955, 1959) müssen die aplacophoren Mollusken auf Grund ihrer
Organisation als zwei unabhángige Klassen von Solenogastres (sensu stricto = sensu
nomine) und von Caudofoveata (welche aus den alten ‘Aplacophora’, oder fälschlich
auch Solenogastres allgemein genannt, herauszulösen sind; vgl. Bryozoa - Kamptozoa)
aufgefasst werden (vgl. p. 196); als zwei convergente Entwicklungslinien würden sie
daher in einem gemeinsamen Begriff ‘Aplacophora’ nur eine künstliche Stadiengruppe,
nicht aber eine natürliche systematische Einheit darstellen.! Zusammen mit den
Placophora bilden Caudofoveata und Solenogastres so die drei Klassen des Mollusken-
Unterstammes Aculifera (früher Amphineura),? --- im Gegensatz zu den fünf Klassen
des zweiten Subphylum Conchifera.

Die SOLENOGASTRES oder Furchenfüsser (Abb. 1; früher Aplacophora-Neomeniida)
stellen 1,5 mm bis 30 cm grosse Aculifera mit seitlich abgerundetem Körper dar,
deren Mantel vollkommen mit Cuticula und Kalkspicula bedecktist; der Fuss ist allein
durch die medioventrale, meist mit mehreren Falten versehene Längsfurche vertreten.
Der Pallialraum zeigt sich durch die seitliche Verschmälerung der Körpers auf eine
subterminale Höhle beschränkt, zusätzlich aber als drüsige Laichgänge in das Kör-
perinnere verlagert (S. HOFFMAN); Ctenidienfehlen, dochbildet die caudale, respira-
torische Pallialraum-Wand verschiedentlich secundäre Atem-Anhänge aus. Der
Verdauungstrakt mit Vorderdarmdrüsen und Radula weist am Mitteldarm seriale
Ausbuchtungen oder Divertikel auf, alternierend mit zahlreichen paarigen Strängen
der Dorsoventral-Muskulatur. Das Nervensystem bildet neben Cerebral-, Ventral-,
Lateral- und Buccalganglien auch an den vier Längsstämmen Concentrationen der
Nervenzellen zu mehr oder minder regelmässig aufgereihten Ganglien aus, an welchen
querverbindende Commissuren und Connective entspringen; an besonderen Sinnes-
organen treten das praeorale Atrium und die dorsoterminale Sinnesgrube auf. Die

‘Wenn auch der Name ‘Aplacophora’ (у. IHERING, 1876) als erste Bezeichnung vor ‘Solenogastres’
(GEGENBAUR, 1878) gegeben wurde, so verliert ersterer durch die Aufteilung der Gruppe in zwei selb-
ständige Klassen sowohl an Wert wie an Sinn; eine Gegenüberstellung von ‘Aplacophora’ (für die Ver-
treter mit Ventralfurche) zu den Caudofoveata (Vertreter mit Ctenidien und Fuss-Schild) wáre jedoch eben-
so irreführend (da die Caudofoveata auch noch aplacophor sind), wie das Belassen einer den Chitonen
gleichwertigen einzigen Klasse von ‘Aplacophora’ mit Solenogastres (oder ‘Ventroplicida’) und Caudo-
foveata als Unterklassen (vgl. BOETTGER, 1955). Wir werden den stammesgeschichtlichen Beziehungen
nur dann einigermassen gerecht, wenn wir drei unabhängige Entwicklungslinien auch systematisch als
drei gleichwertige Kategorien führen (hier als Klassen). Dass GEGENBAUR aus Unkenntnis auch
Chaetoderma in die Bezeichnung Solenogastres (= “Bauchfurcher”, also Furchenfüsser) mit einbezog,
wurde schon von SIMROTH (1894: 131) und ODHNER (1919: 78) beanstandet. Da für höhere System-
kategorien jedoch keine (oft ja unsinnige) nomenklatorische Festlegung besteht, wird vorgeschlagen, jene
Vertreter mit einer ventralen Fussfurche endgültig als die Klasse Solenogastres (sensu nomine;
Furchenfüsser) zu bezeichnen, --- die mit einem postoralen Fuss-Schild und mit echten Ctenidien ver-
sehenen Arten jedoch als eigene Klasse Caudofoveata (Schildfüsser) herauszuziehen. Caudofoveata,
Solenogastres und Placophora bilden daher drei gleichwertige Klassen der Aculifera (SALVINI-PLAWEN,
1967b, 1969).

“auch die Bezeichnung ‘Amphineura’ ist irrefülhrend und daher sinnlos; ein tatsächlich amphineures Nerven-
system (zwei Paar getrennte Markstränge) besitzen nämlich nur die Placophora una die Tryblidiacea
(Neopilina)! Da weder den Solenogastres, noch den Caudofoveata im strengeren Sinn eine Amphineurie
zukommt, und da die Tryblidiacea den Conchifera zugeordnet sind, verliert die Bezeichnung ‘Amphineura’
als Zusammenfassung von Solenogastres, Caudofoveata und Placophora vollkommen an Wert und namen-
gebende Bedeutung. Der Name ACULIFERA (HATSCHEK, 1891) fasst hingegen diese drei Klassen (den
CONCHIFERA gegenüberstehend) mit einem gleichen Merkmalskomplex zusammen, dem Mollusken-Mantel,
und ist daher sowohl vergleichend-anatomisch wie auch rein nomenclatorisch als vollwertig vorzuziehen.
Aculifera (Stachel-Weichtiere) und Conchifera (Schalen-Weichtiere) bilden daher eine sinnvolle Gruppierung
der acht Molluskenklassen in zwei Unterstämme.

194 PROC. THIRD EUROP. MALAC. CONGR.

SU ТИТ

Sp Mf

ERST =

IT | ИЕ Mm m mm
par

ABB. 2. Organisationsschema der Caudofoveata. A. Vorderende, linke Körperwand abgetragen. B.
schräger Querschnitt durch das Vorderende mit Fuss-Schild. С. Querschnitt in der Körpermitte. D. Hinter-
ende, linke Körperwand abgetragen. (Cd, Coelomoduct; Ct, Ctenidien; Dts, dorsoterminales Sinnesorgan;
Ed, Enddarm; Fd, Fussdrüsen; Gc, Cerebralganglion; Go, Gonade; Hm, Horizontalmuskel, Lg, Laich-
gang; Md, Mitteldarm; Mddr, unpaarer Mitteldarmsack; Mf, Fuss-Schild; M5, Mundöffnung; Ns (Nsl, Nsv),
Nervensystem (lateral, ventral); Pc, Pericard; Pr, Pallialraum; Ra, Radulaapparat; Sp, Spicula; Vd,
Vorderdarm; Vddr, Vorderdarmdrisen).

SALVINI-PLAWEN 195

paarigen Keimdrüsen sind hermaphroditisch und die Geschlechtsprodukte werden, da
die eigentlichen Gonoducte rtickgebildet sind, über Pericard, Coelomoducte und Laich-
gánge ausgeleitet; die innere Befruchtung wird durch Samenblasen und háufig auch
durch eine Genitalpapille (Penis) oder gar durch Copulationsstacheln (‘Liebespfeile’)
ergánzt. Die Entwicklung erfolgt tiber eine Húllglocken-, seltener tiber eine Trocho-
phora-áhnliche Larve. Die rein marinen Solenogastres mit 110 Arten in 51 Genera
leben freibeweglich auf der Sediment-Oberfläche, oder epizoisch meist auf Cnidaria.

Die CAUDOFOVEATA oder Schildfüsser (Abb. 2; früher Aplacophora-Chaeto-
dermatida) sind als 3 mm bis 14 cmgrosse Aculifera mit gestrecktem, wurmfórmigen
Habitus charakterisiert, deren Кбгрег vollkommen vom Mantel mit Cuticula und
Kalkschuppen eingehüllt ist und lediglich eine einheitliche oder geteilte, postorale
Grab- und Sinnesplatte freilässt, den Fuss-Schild. Derterminale, glockenförmige Pal-
lialraum weist ein Paar echter Ctenidien auf und zeigt sich weiterhin auch als paarige
Rinne (oder als paariger Gang) in das Körperinnere verlagert. Der Verdauungstrakt mit
Vorderdarmdrüsen und einer teilweise stark umgeformten Radula bildet einen un-
paaren, ventralen Mitteldarmsack aus; regelmässige Ausbuchtungen und seriale
Dorsoventral-Muskulatur sind nur mehr ausnahmsweise, und hier auf den vorderen
Darmabschnitt beschränkt, ausgebildet. Das Nervensystem mit zentralem Cerebral-
Komplex weist allein Buccal- und Ventral-Ganglien auf, doch vereinen sich die late-
ralen Nervenstränge mit der jeweiligen ventralen Bahn, sodass auch die querverbinden-
den Commissuren und Connective auf den vorderen Körperabschnitt eingeschränkt
sind; an der Pallialraum-Glocke befindet sich eine dorsale, längliche und grosse
Sinnesgrube. Die meist verschmolzenen Keimdrüsen sind getrenntgeschlechtlich und die
Genitalprodukte werden, da die eigentlichen Gonoducte (convergent zu den Soleno-
gastres) rückgebildet sind, über Pericard, Coelomoducte und Laichgänge ausgeleitet.
Die Befruchtung findet frei im Meerwasser statt und es treten dementsprechend keine
Genital-Hilfsorgane auf; die larvale Entwicklung ist noch unbekannt. Die rein marinen
Caudofoveata mit 55 Arten in 6 Genera (3 Familien) sind Grab-Formen im Sediment.

Diese skizzierten Organisationsmerkmale vonSolenogastres und Caudofoveata lassen
ihre deutliche Unabhängigkeit voneinander, wie auch von den Placophora erkennen
(vgl. BOETTGER 1955, 1959). Das genaue vergleichend-anatomische Studium dieser
drei Aculifera-Klassen lasst manche der Organisationszilge von Caudofoveata und
Solenogastres bei detaillierter Auflösung als bedeutend ursprünglicher wie bei den
Chitonen erkennen, wobei sich insgesamt die Caudofoveata in der Stammesgeschichte
der Weichtiere am frühesten abgespalten haben müssen (Abb. 4). Es liegt bei ihnen
eine Organisation vor, welche vom gemeinsamen Ausgangspunkt allein durch regres-
sive Umbildungen differenziert erscheint: Alle nicht auch ebenso entweder bei Soleno-
gastres oder bei Placophora anzutreffenden, also als urprünglich anzusprechenden
Merkmale müssen nämlich auf die mit der Lebensweise correlierten Abrundung des
Körpers zurückgeführt werden; allein der gerade Darmkanal mit dem unpaaren Verdau-
ungssack ist als eine gruppeneigene Neubildung zu werten. Von einem turbellario-
morphen, flachen und gleitend-kriechenden “Urmollusken” ausgehend (Abb. 3), dürfte
sich der Caudofoveata-Zweig zur grabenden Lebensweise spezialisiert haben, wobei
der Körper zur Wurmform abgerundet wurde. Das tastende und suchende Graben mit
dem Vorderende bewirkte naturgemáss eine Schrägstellung des gesamten Körpers,
wodurch das Hinterende mit den Kiemen aus dem Sediment ragte. Hier begann auch
die (entgegen BOETTGER 1955: 243) vonhinten nach vorne fortschreitende Rückbildung
des Fusses, welcher erst mit der lokomotorischen Anpassung an die neue Gestalt
(Schwellkörper-graben) auch am Vorderende verschwand; die postorale Grab- und
Sinnesplatte, der Fuss-Schild, stellt jedoch noch diesen letzten Fussrest dar (vgl. p.
196 und HOFFMAN 1949: 376-384). Diezum Atmen der nunmehrigen Sedimentbewohner
lebensnotwendigen Ctenidien blieben daher erhalten, rückten aber mitdem Pallialraum
nach terminal.

196 PROC. THIRD EUROP. MALAC. CONGR.

Der postorale Fuss-Schild zeigt durch seine Histologie und durch die lateralen
Drüsenbildungen eine detaillierte Gleichheit mit dem Molluskenfuss der Solenogastres
(S. HOFFMAN 1949: 352-362, 372-385). Die cerebrale Innervierung des Fuss-
Schildes erzwingt jedoch seine Homologie allein mit dem vorderen, cerebral inner-
vierten Abschnitt des Fusses bei jenem gemeinsamen Vorfahren (Urmollusk, Abb. 3)
mit noch der gesamten Ventralfläche als lokomotorisches Gleitorgan. Die Unterteilung
dieser Ventralfläche in einen rein lokomotorisch-pedalen (ventral innervierten) Fuss
und in einen praepedal-oralen (cerebral innervierten) “Kopf”-Abschnitt erfolgte daher
erst nach Abspaltung der Caudofoveata, was durch die erst danach entwickelte,
kompakte und ventral innervierte Fussdrüse (Solenogastres, Placophora; Conchifera)
belegt wird. Der Fuss-Schild der Caudofoveata stellt somit sowohl einen (Ur-)Mol-
luskenfuss-Rest dar, wie er zudem die deutlich basal abgezweigte Stellung der Caudo-
foveata innerhalb der Aculifera belegt.

Die Stufung bei der Spicula-Bildung innerhalb der Aculifera in 1. eine intrazelluláre
Anlage, welche den Kontakt zum Epithel verliert (Caudofoveata, Solenogastres, Placo-
phora), in 2. eine intrazelluläre Anlage mit Zellschlauch und basalem Cuticula-
Becher (Solenogastres, .Placophora), sowie in 3. eine Bildung aus mehreren Zellen
(nur bei Placophora) zeigt eine deutliche Differenzierungs-Abfolge. Sie ist zusammen
mit der Spikeltypen-Zahl bei Caudofoveata (1), bei Solenogastres (1+2) und bei Placo-
phora (1+4 mit zahlreichen Abwandlungen) als ein weiterer Beleg für die basale Ab-
zweigung der Caudofoveata innerhalb der Mollusken-Phylogenie zu werten.

ABB. 3. Rekonstruierte Stammform der Mollusken (‘Ur-Mollusk’) von dorsal. Cd, Coelomoduct; Ct
Ctenidium; DVM, Dorsoventral-Muskulatur; Gc, Cerebralganglion; Gd, Gonoduct; Go, Gonade; Hz,
Herz; Int, Spicula-tragendes Integument (Stachel-Cuticula); Md, Mitteldarm; №1, laterales und NSv
ventrales Nervensystem; Pc, Pericard; Pr, Pallialraum; Ra, Radula; So, Sinnesorgan). je

SALVINI-PLAWEN 197

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CONCHIFERA

ACULIFERA

Verwandtschaftsbeziehungen
der rezenten und einiger (+)
fossiler Weichtiergruppen

АВВ. 4. Phylogenie der Mollusca: Verwandtschaftsbeziehungen der recenten und einiger fossiler
Weichtiergruppen.

Die Solenogastres dürften sich hingegen ganz gegenteilig umgebildet haben, da sie
sich trotz des schmalen Fusses (Fussfurche) allein mit dessen Hilfe auf Cilien fort-
bewegen (SALVINI-PLAWEN 1968 b). Die stammesgeschichtliche Umbildung von dem
turbellariomorphen, flachen und gleitend-kriechenden ‘Urmollusken’ (Abb. 3) muss
daher derart vermutet werden, dass nicht eine Anderung in der Bewegungsart einge-
treten ist (wie es BOETTGER, 1955: 237 ff, annehmen möchte), sondern dass die
Lebensweise geändert wurde; sie verlangte in zunehmendem Masze eine grössere
Beweglichkeit, d.h. dass hier durch eine mehr schliefende oder windende Lokomotion
eine Körperverschmälerung begünstigt wurde. Die vollständige Rückbildung der
Ctenidien kann ebenfalls daraus erklärt werden, da die Solenogastres als Bewohner

198 PROC. THIRD EUROP. MALAC. CONGR.

der Sediment-Oberfläche auf Grund ihres steten Kontaktes mit dem freien Wasser
genügend Gasaustausch durch die Körperhaut bestimmter Regionen erhielten (was bei
einer grabenden Fortbewegung, vgl. BOETTGER, nicht vorstellbar wäre) und dadurch
die Kiemen ohne grosse Einbusse der Atmung verschwanden. --- Die Solenogastres
zeigen aber durch detaillierte Übereinstimmungen mit den Placophora im Fuss mit
Fussdrüse und im spiculatragenden Integument (vgl. p. 196), dass ihre Stammes-
geschichte zumindest bezüglich dieser Merkmale eine Zeitlang mit den Käferschnecken
gemeinsam verlief; in ihrer eigenständigen Phylogenie nach der Abspaltung haben sie
sich jedoch trotz der habituellen Umformung (mit Verlust der Gonoducte und Ctenidien)
in etlichen Merkmalen progressiv differenziert (vgl. Geschlechtsapparat).

Die Placophora wiederum haben offensichtlich die ursprüngliche Körperform der
turbellariomorphen, flachen und gleitend-kriechenden Stammform (Abb. 3) gross-
teils beibehalten (vgl. auch Nervensystem), wenn auch etliche Merkmale eigenständig
spezialisiert sind (Mehrfachbildung der Ctenidien, Verdauungstrakt, Schalenplatten);
sie erscheinen aber vor allem durch die Ausbildung der acht dorsalen Kalkplatten
samt der davon abhängig concentrierten Dorsoventral-Muskulatur in Richtung auf die
späteren Conchifera höher differenziert.

ABB. 5. Das Nervensystem von Neopilina (aus LEMCHE & WINGSTRAND, 1959). 3-10, 3. bis 10.
Lateropedal-Connectiv; A-E, Ctenidien.

SALVINI-PLAWEN 199

N
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OH

И)

D) 4
EQ
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Zp,
7 |
YH AN
РЕ Е
|

o
A А /
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/ Y

ABB. 6. Das Muskelsystem von Neopilina (aus LEMCHE & WINGSTRAND, 1959). I-VI Dorsoventral-
Muskelstränge.

Diesen umrissenen Grundzügen zufolge erkennen wir also die Entwicklung von drei
unabhängigen Gruppen Caudofoveata, Solenogastres und Placophora aus einer gemein-
samen Stammform (‘Urmollusk’), welche gemäss den systematischen Prinzipien auch
mit der gleichwertigen System-Kategorie eingeordnet werden müssen. Es braucht
nach den obigen Ausführungen wohl nicht mehr besonders betont werden, dass eine
Ableitung der Solenogastres und Caudofoveata von Placophora --- quasi von Crypto-
chitoniden durch Dorsalplatten-Verlust (wie noch häufig, besonders in der Paläon-
tologie, vertreten wird) --- ebenso unhaltbar ist, wie die Proklamation von Neopilina
als eine dem Ursprung der Mollusken nahestehende Form; die Stammform der Weich-
tiere hatte zweifellos eine aculifere Organisation (vgl. BEEDHAM & TRUEMAN, 1968:
448-450).

2. PHYLOGENETISCHE BEDEUTUNG EINZELNER ORGANE

Im Anschluss an den Organisations-Abriss von Solenogastres und Caudofoveata
sollen einige charakteristische Bauplan-Merkmale herausgegriffen werden, welche
die jeweiligen morphologischen Beziehungen der Vertreter der beiden Klassen deut-
lich hervorheben und die phylogenetische Bedeutung darlegen.

200 PROC. THIRD EUROP. MALAC. CONGR.

ABB. 7. Organisationsschema von Neopilina, (aus LEMCHE & WINGSTRAND) nach Abb. 5 & 6 korrigiert!
(Ct, Ctenidien; DVM, Dorsoventral-Muskelbündel; Go, Gonaden; Ne, Nephridien; NS, Hauptnervensystem).

a) Muskulatur

Abgesehen vom vollstándig erhaltenen, dreischichtig ausgebildeten Hautmuskel-
schlauch bei Solenogastres und Caudofoveata, zeigt sich, dass ihnen auch die bei allen
Weichtieren zwischen Mantel und Fuss verlaufenden, charakteristischen Dorsoventral-
-Stránge zu eigen sind. Durch die júngsten Funde recenter Tryblidiacea hat sich
zudem eine klaffende Merkmalslücke bedeutungsvoll geschlossen, denn entgegen dem
verfälschten Neopilina-Organisations Schema (welches so oft abgebildet wird)
zeigen sich nämlich die Muskelbündel, das Nervensystem, die Ctenidien und die Ne-
phridien bei Neopilina lagemässig keineswegs übereinstimmend correliert (wie die
anatomischen Darstellungen von WINGSTRAND einwandfrei belegen: Abb. 5, Ctenidium
A müsste beidem 6. Connectivliegen!); darüberhinaus sind die Muskelstränge I und VII
noch deutlich zweiteilig (Abb. 6)! Damit schliesst sich aber das allgemeine Bild zu
einer lückenlosen Concentrationsreihe (Abb. 8):

Die Solenogastres weisen einheitlich eine durchgehende Serie von paarigen, sich am
Fuss überkreuzenden Dorsoventral-Strängen auf (entgegen der Behauptung von LEMCHE
1959: 431), und selbst für die weitgehend rückgebildeten Caudofoveata konnte bei einer

SALVINI-PLAWEN 201

júingst entdeckten, relativ urspriinglichen Art (Scutopus ventrolineatus) im Vorder-
kórper eine gleichartige Anordnung der Muskulatur aufgefunden werden. Eine der-
artige Strangreihe hat mit der Anlage von mehreren dorsalen Kalkplatten verständ-
licherweise eine daraufhinführende Concentration erfahren, sodass die acht beweg-
lichen Schalenstticke der Káferschnecken daher mit je zwei Paar Dorsoventral-Biindel,
zusammen also mit 16 hintereinanderliegenden Strangpaaren gegen den Fuss hin
verankert sind. Die stammesgeschichtliche Verschmelzung jener dorsalen Kalk-
platten zu einer einheitlichen Concha (vgl. BOETTGER; 1955: 250; 1959: 388) findet
in der weiteren Concentration der Dorsoventral-Muskulatur ihr Aquivalent, was inner-
halb der Tryblidiacea festzustellen ist; die in vielen anderen Merkmalen weitgehend
spezialisierte Neopilina (Abb. 7) gibt uns mitihren 8 bzw. 10 Strangpaaren ein recentes
Beispiel dieser Ubergangsformen (Verschmelzung von je zwei Käferschnecken-Strängen
zu einem Bündel). Die weitere Verdichtung und Concentration der nun als Schalen- oder
Fuss-Muskel bezeichneten Dorsoventral-Stränge innerhalb der Conchifera ermöglichte
Hand in Hand damit eine zunehmende Beweglichkeit des Tieres in der Schale und (bei
Gastropoda, Scaphopoda und Kephalopoda) das Absetzen eines distincten Kopfabschnittes,
wodurch der Mantel mit Concha auf den Eingeweidesack beschränkt wurde. So lassen
sich die Gastropoden über Zustände ableiten, wie sie die fossilen Gattungen der Try-
blidiacea Drahomira PERNER (7 Muskelpaare), Tryblidium LINDSTRÖM, Pilina
KOKEN, etc. (6 Muskelpaare), Cyrtonella HALL (3-2 Muskelpaare) und Sinuitopsis
PERNER (3 Muskelpaare) zeigen, und wie die Bellerophontacea (1 Muskelpaar) über-
leiten. Dass die mit Sinus oder Schlitzband versehene Concha der Bellerophontacea
noch exogastrisch gewunden war, belegen die Verhältnisse bei der genannten Sinuitopsis
acultiliva (HALL), welche trotz der noch drei-paarigen Muskeln schon (wie auch
Cyrtolites ornatus CONRAD?) einen Sinus zeigt (ROLLINS & BATTEN, 1968); die
absolute Symmetrie des einzigen Muskelpaares der Bellerophontacea (vgl. KNIGHT,
1947) spricht zudem gegen eine schon eingetretene Torsion. Die erst danach erfolgte
mutative Torsion des Eingeweidesackes um 180° --- der bereits vorhandene Sinus
(bzw. das Schlitzband) begünstigte hierbei das Überleben der tortierten Formen
(Ableitung der Faeces nach oben) --- bedingte bei den echten Gastropoda daher die
Rückbildung des primär rechten Muskels und die Drehung der Schalenschnecke nach
hinten: endogastrische Concha (Schlitzband und Pallialraum vorne: Prosobranchia),
welche mit einem unpaaren (ursprünglich linken, nun) rechten Spindelmuskel verstrebt
ist; Reste des Gegenmuskels sind bei wenigen Arten erhalten.

Für die Bivalvia wird die zunehmende Concentration der Dorsoventral-Muskulatur
in einer median geknickten (zweiklappigen) Tryblidiaceen-Schale (Diplacophora) einer-
seits durch die actinodonte Babinka BARRANDE (8 Muskelpaare; vgl. MCALESTER,
1965) fossil, recent (atavistisch?) durch Formen wie Modiolus (7 Paare), Mesodesma
(5 Paare) u.a.m. belegt, und andererseits durch die ctenodonten Protobranchia (Nucula,
Yoldia, Nuculana, mit 6-3 Muskelpaaren; vgl. YONGE 1953). Ähnliche Muskel-Concen-
trationen lassen sich schliesslich auch für die Scaphopoda und Kephalopoda annehmen.

Der besonders in der Paläontologie vertretenen Ansicht, dass die Käferschnecken
sich (völlig unverständlich) durch “Zerfall” der Concha in acht Schalenplatten dif-
ferenziert hätten (YONGE, 1939: 133; FRETTER & GRAHAM, 1962: 8), stehen die
eindeutigen Verhältnisse bei Solenogastres und Caudofoveata markant gegenüber.
Zudem ist die Gelenkigkeit der 8 Platten nur auf eine primäre Einrollfähigkeit der
(aculiferen) Tiere zurückzuführen, nicht jedoch von einem conchiferen Zustand her!
Auch scheint die Tatsache noch nicht aufgefallen zu sein, dass an Muskeleindrücken
bisher stets nur acht Paar oder weniger, nicht aber mehr aufgefunden wurden (vgl.
McALESTER, 1965: 236), obwohl sie allerdings auch (als geteilt) in 16-Zahl auftreten
könnten: Alle Mollusken vor dem phylogenetischen Erscheinen der Tryblidiacea bzw.
Placophora waren zwar mit mehr als 8 bzw. 16 Strangpaaren versehen, besassen aber

PROC. THIRD EUROP. MALAC. CONGR.

dl 4

ane

| i 3

SALVINI-PLAWEN 203

noch keine Schalen, --- können (!) daher auch nicht beschalt aufgefunden werden. Zu-
dem begünstigt eine konisch gewölbte Schale allein eine Concentration, wodurch auch
secundär vermehrte Muskelstränge unwahrscheinlich sind (vgl. auch BOETTGER, 1955);
die Eindrücke bei den Verwandten der fossilen Gattung Stenothecoides RESSER sind
hingegen nicht als Dorsoventral-Muskeln zu werten, und zudem stellt die Gruppe der
teils asymmetrischen Arten (Stenothecoida) durch die Zweiklappigkeit (YOCHELSON,
1969) wenn überhaupt Conchifera, so einen Seitenzweig der Muscheln dar.

Es ergibt sich zusammenfassend somit eine lückenlose Concentrationsreihe der
zahlreichen Strangpaare vom Solenogastren-Zustand über das Placophoren- und
Tryblidiaceen-Stadium bis zu den Gegebenheiten bei Gastropoda, Bivalvia, Scaphopoda
und Kephalopoda (Abb. 8). Der phylogenetische Ausgangspunkt für die Mollusken-
wurzel ist also in einer Anordnung zu suchen, wie sie die Dorsoventral-Muskulatur
heute noch bei Solenogastren zeigt (vgl. Abb. 1, 3).

b) Darmtrakt

Ein solcher stammesgeschichtlicher Anschluss von den Weichtieren zurück lasst
sich leicht in den Muskulatur-Verhältnissen verschiedener Plathelminthen-Gruppen
erkennen (Abb. 8). So sind z.B. bei Turbellarien ohne Divertikel-Darm die
dorsoventralen Muskelfasern ungeordnet und netzartig verknüpft (bei jenen Formen
der, nach KARLING 1967, Archoophora, Prolecithophora, Proseriata, Rhabdocoela
und Lecithoepitheliata, deren Darmrohr nicht dem Hautmuskelschlauch anliegt); die
vorwiegend grösseren Vertreter weisen hingegen durch einen Divertikel-Darm als
Verteiler-System bereits eine correlierte Gruppierung der Muskelfasern zu serialen
Strängen auf (Polycladida, Tricladida). Dieses zweite Bild findet sich nun in völliger
Gleichheit auch bei den Solenogastres: ein mit serialen Aussackungen versehener
Mitteldarm, in dessen Aussparungen die Muskelstränge verlaufen. Da die derartige
Muskulatur-Anordnung bei den Plathelminthes und bei den Mollusken (wie auch Nemer-
tinen) --- wie die vergleichende Anatomie ergibt --- durch die ventrale Sohlenbewegung
nicht im Zusammenhang mit speziellen Lokomotionsorganen (Peristaltik, Borsten,
Beine) entstanden sein kann, ist allein die, durch die mit der habituellen Vergrösse-
rung bedingte Anlage von Darmaussackungen als Ursache für die Fasern-Aufteilung zu
sehen. Da nun weiterhin selbst jene Solenogastres-Arten ohne Divertikeldarm die
serialen Muskelstränge besitzen (es sind fast durchwegs kleine Vertreter), ist ein
solches Fehlen von Aussackungen als secundär zu betrachten (Zwergformen, tierische
Nahrung). Wir sind somit mit gutem Grund berechtigt anzunehmen, der ursprüng-
lichsten Ausgangsform der Weichtiere, dem ‘Urmollusk’ (Abb. 3), einen Divertikel-
darm zuzusprechen, --- So wie er bei den recenten Solenogastres (und teils auch
Caudofoveata) noch vorliegt.

c) Ernährung und Lokomotion (Coelomfrage)

Die Frage nach der ursprünglichsten Form der Radula wird allgemein zugunsten
des zweiteiligen Typus erörtert (vgl. BOETTGER 1955, 1959), womit nicht nur durch
die Anwesenheit der Radula allein, sondernbesonders durch diese ursprüngliche Zwei-
teiligkeit (vgl. die häufige Endgabelung der Gastropoden-Radulascheide) auf eine
carnivore Ernährung der Mollusken-Vorfahren geschlossen werden kann. Die sowohl
bei Solenogastres (Abb. 9) wie auch bei Caudofoveata (Abb. 10) primär ausgebildete
distiche Räuber-Radula stellt eine zusätzliche Bestätigung dar. Da jene Coelomata,
welche sich als errante Formen Substrat-gebunden repräsentieren, generell im Zu-
sammenhang mit der Coelomanlage zu Microphagen oder Detritusfressern geworden
sind (grabende Lebensweise ! vgl. Echiurida, Sipunculida, Annelida, Branchiotremata),
liegt hierin ein deutliches Indiz, dass die Mollusken als carnivore Formen (vgl. be-
sonders die ursprünglicheren Solenogastres) ihre ursprüngliche Lebensweise bei-

204 PROC. THIRD EUROP. MALAC. CONGR.

TI TE
AN yA A Y, О if ff

E F G H

ABB. 9. Verschiedene Radula-Typen (je eine Querreihe) bei Solenogastres. A. Cyclomenia holoserica.
B. Kruppomenia minima. C. Epimenia verrucosa. D. Genitoconia atriolonga. E. Dondersia californica.
Е. Dorymenia weberi. G. Anamenia amboinensis. H. Alexandromenia crassa (schwarz = Radula-Zähne
punktiert = cuticulare Basis; nach verschiedenen Autoren zusammengestellt).

A,
IN

ABB. 10. Reduktionsreihe der Radula (je eine Querreihe) bei den Caudofoveata. A. Scutopus. B. Pro-
chaetoderma. С. Falcidens. D. Chaetoderma (schwarz = Radula-Zähne, punktiert = cuticulare Basis;
Original, leicht schematisiert).

behalten und damit auch keine durchgreifende Bauplanänderungen wie die Anlage eines
Körper-Coeloms erfahren haben.

Im Gegensatz zu den Solenogastres sind die Caudofoveata jedoch grabende Formen.
Diese Lebensweise kann aber mit Bestimmtheit als secundär bezeichnet werden, denn
einerseits ist bei den ursprünglicheren Limifossoridae (die Genera Limifossor,
Scutopus, Metachaetoderma) eine mehrreihige, distiche Greif-Radula ausgebildet
(Abb. 10A), diese zeigt aber andererseits bei den Chaetodermatidae (Falcidens, Chaeto-
derma) durch die Ernährung der Tiere als Partikelfresser im Substrat derart radikale
Rückbildungen (Abb. 10C, D), dass hier kaum mehr von einer Radula im engeren Sinne
gesprochen werden kann! Die Lokomotion der Caudofoveata erfolgt hingegen auf Grund
ihres durch die Lebensweise reduzierten Fusses mit Muskulatur und Körperlymphe
als Schwellkörper-System, so wie es TRUEMAN (1968) für zahlreiche weitere Grab-
formen angibt (vgl. Bivalvia, Scaphopoda, Gastropoda-Naticidae und -Kephalaspidea;
Enteropneusta, etc.). Die grabende Fortbewegung der Caudofoveata ist so z.B. direkt

SALVINI-PLAWEN 205

mit den Sipunculida vergleichbar, welche allerdings mit einem Kórper-Coelom versehen
zum Graben praedestiniert sind. Die wenig vollkommene Lokomotion der Caudofoveata
(SALVINI-PLAWEN, 1968a) erfolgt mit Hilfe des Haemocoels des Vorderkörpers (vgl.
Nemertini; bei Bivalvia und Scaphopoda dagegen mit dem Fuss-Haemocoel) und wäre
daher mit Hilfe eines Körper-Coeloms ungleich besser (vgl. Sipunculida, Entero-
pneusta). Da die funktionelle Ursache ansich also gegeben ist, warum ist ein der-
artiges hydrostatisches Lokomotions-Skelett, das Körper-Coelom, bei Weichtieren
nicht ausgebildet? --- und zwar atavistisch, wenn es schon stammesgeschichtlich
vorhanden gewesen sein soll (vgl. Echiurida: Bonellia-Weibchen ohne Coelom,
Zwergmännchen aber mit Coelom!). Auch hiermit ergibt sich also der zwingende
Schluss, dass die Mollusca kein Körper-Coelom besessen haben.

In einer eigenen Studie war schon auf die ursprüngliche Bedeutung und auf die zu
folgernde Entstehung des Gonopericardial-Coeloms der Mollusken ausführlich einge-
gangen worden (SALVINI-PLAWEN, 1968c), womit nur resumierend festgehalten zu
werden braucht, dass sich im Weichtierstamm eine gruppeneigene, coelomatische
Bildung sui generis differenziert hat, welche primär als schützende Herzblase (zur
Sicherung des Gleitraumes der Herzpumpe) angelegt und durch Einlagerung der Keim-
zellen schliesslich funktionell-bedingt in Gonocoel und Pericard unterteilt wurde.
Da das mit den Turbellarien und Nemertinen tibereinstimmende amere Bauprinzip
(acoelomate Organisation) den Beleg dafür gibt, dass dem Molluskenstamm die ciliare
Sohlenlokomotion typisch zu eigen war (undteilsnochist), kann schon daraus (entgegen
GUTMANN, 1966) nicht angenommen werden, dass sich die Mollusken-Ahnen auf andere
Weise fortbewegt hätten. Zudem sehenwir, dassz.B. bei den Hirudinea (welche gegen-
über den Solenogastren oder Placophoren zweifellos als höher differenziert betrachtet
werden müssen) zwar kaum mehr eine echte Spiralfurchung auftritt, doch aber eine
deutliche Anlage von metameren Coelomsäcken; wie viel klarer wäre daher erst recht
bei den ursprünglicheren Mollusken eine zumindest vorübergehende Körpercoelom-
Bildung zu erwarten, wenn die Spiralfurchung sogar als typisch vorliegt. Noch ein-
schneidender werden die Verhältnisse im Vergleich zu den stark abgeleiteten Arthro-
poden oder den parasitischen Pentastomiden, bei welchen Gruppen trotz dem Mangel
jeglicher Anhalte bei der Furchung doch aber die (metameren) Coelomsäcke zur Aus-
bildung kommen; --- und ausgerechnet die weniger differenzierten, freilebenden Weich-
tiere (bes. Aculifera) sollten bei einem ehemals angeblich vorhanden gewesenen Kör-
percoelom keine Anklänge in der Ontogenie (oder weiteren Morphologie) zeigen,
obwohl für die atavistische Coelombildung ja ausgesprochen praedestinierte Grab-
formen auftreten (Caudofoveata, Bivalvia, Scaphopoda)? So ist also die gleitend-
kriechende Sohlenbewegung der Mollusken als ursprünglich zu betrachten. Diese
vererbte Fortbewegung auf der ventralen Körperseite mit Cilien erübrigt ja ein loko-
motorisches Coelom, denn eine flüssigkeitserfüllte secundäre Leibeshöhle wird erst
bei einer Bewegungsform notwendig, welche einen geschlossenen Hautmuskelschlauch
wirken lassen soll, etwa wie bei grabender oder peristaltischer Fortbewegung (vgl.
CLARK, 1964), --- ein Hydroskelett erübrigt sich daher bei allen Formen mit
ciliarer Fortbewegung oder ventraler Sohlen-Lokomotion!

Diese auch von REMANE (1967: 614) vertretene Ansicht enthält den Schlüssel zur
funktionell-bedingten Coelom-Bildung schlechthin, denn es wird klar, dass erst eine
aus verschiedenen Gründen induzierte Einbusse der ciliaren Lokomotion bei nicht-
sessilen Organismen die Herausdifferenzierung eines hydrostatischen Kórper-Coeloms
begünstigte.

REMANE widerspricht sich allerdings selbst hinsichtlich seines postulierten
‘Urcoelomaten’, welchen er an die Wurzel von Protostomia und Deuterostomia stellt,
also an die Wurzel der Pilateria (1967: 606):

a) Das Hydroskelett (Körpercoelom oder secundäre Leibeshöhle) istfür die Wirkung

des Hautmuskelschlauches, der es umgibt, erforderlich (REMANE, 1967: 614);

b) Bei schlängelnder oder peristaltischer Bewegung ist ein geschlossener Haut-
muskelschlauch notwendig (loc. cit.);

206 PROC. THIRD EUROP. MALAC. CONGR.

с) Ciliare Lokomotion oder Fortbewegung auf ventralem Fuss macht ein Кбгрег-
coelom überflüssig, bzw. ein vorhandenes Coelom wird dadurch bedeutungslos
und kann eingeengt oder aufgelöst werden (loc. cit.);

d) Die Fortbewegung durch Wimpern ist ursprünglich (primitiv) (loc. cit.).

Daraus folgt: ein ursprüngliches Tier mit Wimpern-Lokomotion benötigte kein
hydrostatisches Coelom.

Wieso hat aber dann REMANE’s Urcoelomat (1967: 604-605, Abb. 6) Cilien (-Bewegung)
und ein (funktionall ja Uberflüssiges) dreiteiliges Coelom???

ABB. 11. Körperende von Falcidens crossotus (Caudofoveata) mit exponierten Ctenidien (Lebendphoto).

ABB. 12. Schräger Schnitt durch den Pallialraum von Prochaetoderma californicum (Caudofoveata).
(Lam, Kiemenlamelle; Sch, Ctenidium-Schaft).

d) Ctenidien

Ein Blick auf die Verhältnisse des Pallialraumes ist ebenfalls einer genaueren,
auflösenden Betrachtung wert. Die Discussion um die ursprüngliche Zahl der Ctenidien
findet einerseits in der Theorie Ausdruck, wonach es sich bei den höheren Conchifera
um eine Reduktion der Kiemen zur Zweizahl handelt, ausgehend von einigen Paaren
wie bei Neopilina (vgl. FRETTER & GRAHAM, 1962), --- andererseits wird hingegen
die höhere Ctenidienzahl bei Placophoren, bei Neopilina und Nautilus als Mehrfach-
bildung eines einzigen Paares angesehen (YONGE, 1947; BOETTGER, 1955, 1959).
Letztere Ableitung gewinnt eine ungleich höhere Wahrscheinlichkeit angesichtsder zwei
Ctenidien bei den ja früh abgespaltenen Caudofoveata (Abb. 11). Dieses einzige Kiemen-
paar könnte man allerdings ebenfalls wiederum als ein Reduktionsprodukt erklären
(wie man alles, was sich nicht in eine vorgefasste Theorie einfügt, mit Reduktions-
Postulaten übergehen kann), und tatsächlich wurden auch bei Prochaetoderma califor-
nicum “two pairs of gills of a rather primitive structure” gemeldet (SCHWABL, 1963:
267). Eine Überprüfung ergab jedoch, dass es sich in Wahrheit nicht um zwei Paar
ursprüngliche, sondern um ein einziges, hochdifferenziertes Ctenidien-Paar handelt
(Abb. 12), welches --- analog zu den Bivalvia --- je zwei stark vergrösserte Kiemen-
blätter pro Schaft ausbildet. Da aber damit nicht der Platzmangel für die Ctenidien-
zahl bestimmend sein kann (vier Kiemenblätter haben ja Raum), und da sich bei
Vergrösserung der Respirationsfläche in dieser ursprünglicheren Gruppe wohl eher

SALVINI-PLAWEN 207

atavistisch die Anlage eines zweiten Kiemenpaares gebildet haben wiirde (wenn es
schon einmal vorhanden gewesen wäre) als еше komplizierte Umgestaltung des phylo-
genetisch Fixierten, --- daraus darf man somit dem einzigen Ctenidienpaar der Caudo-
foveata mit gutem Grund phylogenetische Bedeutung beimessen. Schliesslich weist ja
das Vorhandensein von nur zwei Herz-Atrien (auch der polybranchiaten Placophora)
deutlich darauf hin (bei Caudofoveata ist das doppelte Atrium verschmolzen-unpaar
und meist nur durch die beiden Atrioventricular -Offnungen ersichtlich), dass ihnen
zugeordnet (!) nur zwei Ctenidien als ursprünglich anzunehmen sind (vgl. H. HOFF-
MANN, 1951: 181).

Nach neueren Befunden scheint auch keineswegs mehr so sicher, dass auch den
Vorfahren des tetrabranchiaten Nautilus zwei Ctenidienpaare zukamen. Da nun belegt
werden konnte, dass sowohl die Baktriten als Ausgangsgruppe für die Ammonoidea
und Endocochlia (= Dibranchiata), wie auch die Goniatiten der Ammoniten selbst nur
wenig (10? --- keinesfalls aber 80-90) Fangarme besessen haben (KOLB, 1961;
ZEISS, 1968), einen Tintenbeutel aufwiesen (LEHMANN, 1967b) und zudem eine nur
sieben-zähnige Radula zeigten (LEHMANN, 1967a), ist auch den exogastrischen Am-
moniten eine annähernd dibranchiate Organisation beizulegen. Wennauch die Kiemen-
zahl der fossilen Formen wohl nicht festzustellen sein wird, so ist doch die Ursprüng-
lichkeit der Nautilus-Organisation äusserst zweifelhaft geworden. Zwar erweist sich
die Zehnarmigkeit der Baktriten und Goniatiten insofern als unbefriedigend, als die
6-10 zipfelige, mit Saugnäpfen bewehrte Buccalmembran der recenten Decabrachia
als Fangarm-Rudimente aufgefasst werden müssen, --- doch ist eine daraus resul-
tierende 16-20 Armigkeit als ursprünglicher Zustand wohl vertretbar.

e) Larven

In einer Gegenüberstellung von Larven-Merkmalen istinnerhalb der Aculifera der
Vergleich auf die Verhältnisse bei Solenogastres und Placophora beschränkt, da die
Entwicklung der Caudofoveata noch nicht erforscht ist.

Der für die Anneliden-Verwandtschaft der Mollusken stets hervorgehobene Ver-
gleich der jeweiligen Ontogenie hat bei genauer Betrachtung etliche ‘Schönheitsfehler’
von weittragender Bedeutung: Zunächst besteht bekanntlich der tiefgreifende Unter-
schied in den sog. ‘Kreuz-Bildungen’ innerhalb der Spiralfurchung, welcher nur über
so neutrale nicht-determinierte Zustände wie bei den Turbellaria erklärbar ist. Die
nach PRUVOT (1890) und BABA (1940, 1951) auch bei Solenogastres auftretende
Kreuzbildung fügt sich in das Bild der Mollusken ein (Nematomenia banyulensis
mit Dentalium-ähnlicher, Epimenia verrucosa mit Patella- oder Ischnochiton-ähnlicher
Ausbildung); trotz dieser bei Mollusken und Anneliden so durchgreifenden Unterschiede
werden die jeweiligen Larven oft allzu gewollt gleichgesetzt. Eine weitere, folgen-
schwere Abweichung zeigt sich nämlich auch in den Larven selbst (Abb. 13), als bei
Bivalvia-Protobranchia und bei Solenogastres eine sogenannte Hüllglocken-Larve
ausgebildet wird, --- ein Typus, welcher auch noch bei den Scaphopoda anklingt und
bei welchem der eigentliche Embryo (Imaginalkörper) von einer Hülle grosser Deck-
zellen umgeben ist. Diese Hüllglockenlarve (engl. Testcell-larva) muss durch ihre
Übereinstimmung bei systematisch so weit entfernten Gruppen, zudembei so ursprüng-
lichen Vertretern wie Solenogastres und Bivalvia-Protobranchia (teils auch Scaphopoda),
als Stamm-eigen betrachtet und also an die Wurzelder Mollusken gestellt werden, ---
so wie verschiedentlich schon betont worden ist (DREW, 1901; YONGE, 1939;
THOMPSON, 1960). Die leicht denkbare Abwandlung der Hüllglockenlarve zum
Trochophora-Typus (Hüllglocke = Prototroch-Abschnitt = Velum) und weiter zur
Veliger-Larve einerseits (vgl. DREW, 1901: 338; CHANLEY, 1968), und die starken
Ähnlichkeiten dieser Hüllglocken-Ontogenie mit den Larven von Turbellarien und
Nemertinen, von Sipunculus nudus und der Anneliden-Endolarve (Serosa = ectoderme
larvaire = Hüllglocke, Amnionhöhle = Peri-Imaginalraum; vgl. HATSCHEK, 1884 und
DAWYDOFF, 1959) wie Mitraria andererseits (Abb. 14),--- diese Beziehungen lassen
nicht nur auf die Ursprünglichkeit des Hüllglocken-Typus innerhalb der Weichtiere
schliessen, sondern sie deuten auf eine tief in den stammesgeschichtlichen Entwick-

208 PROC. THIRD EUROP. MALAC. CONGR.

ABB. 13. Mollusken-Larven. A-D. Hüllglocken-Typus. E-F. Ubergangs-Typus. G-H. Trochophora-
Typus. I-M. Veliger-Typus. А. Nematomenia banyulensis und В. Neomenia carinata (Solenogastres).
C. Yoldia limatula und D. Nucula proxima (Bivalvia-Protobranchia). E. Epimenia verrucosa (Solenog.).
Е. Dentalium dentale (Scaphop.). G. Patella sp. (Gastropoda). Н. Ischnochiton magdalenensis (Placophora).
Ч. Dreissena polymorpha (Bivalvia). К. Gasteropteron rubrum. L. Nassa sp. М. Murex ramosus (Gastro-
poda); (nach verschiedenen Autoren, wenig verändert).

SALVINI-PLAWEN 209

АВВ. 14. Längsschnitte durch Larven vom Hüllglocken-Typus. A. Neomenia carinata (Solenogastres).
В. Nucula proxima (Bivalvia-Protobranchia). С. Sipunculus nudus (Sipunculida). D. Polygordius sp.
(Archiannelida). E. Sipunculus nudus. Е. Lineus, ruber (Nemertini). (Ec, imaginales Ectoderm: Hg,
Húllglocke; Pi, Periimaginalraum) (nach verschiedenen Autoren).

210 PROC. THIRD EUROP. MALAC. CONGR.

lungs-Vorgángen verwurzelte Larve, als deren Differenzierung erst mannigfaltig
der Trochophora-Typus convergent fixiert worden ist. Dementsprechend finden wir
nicht nur bei den Bivalvia diese Schritte repräsentiert (Abb. 13C, D-J; vgl. CHANLEY,
1968), sondern auch innerhalb der Solenogastres (Abb. 13A, В-Е) tritt der fort-
geschrittenere, Trochophora-ähnliche Ubergangstypus bei Epimenia auf; nur mehr
die Andeutung einer Htillglocke und eines Imaginalzapfens zeigt sich gleicherweise
auch bei Dentalium. Ein ähnlicher Differenzierungs-Weg ergibt sich auch bei den
Sipunculiden (Sipunculus --- tibrige Vertreter) und bei den Anneliden (Endolarve,
Mitraria --- Trochophora).

Ein náchstes Kriterium ergibt sich aus der Tatsache, dass bei allen ursprting-
licheren Mollusken (Solenogastres, Placophora, Scaphopoda, Bivalvia-Protobranchia
und fast allen marinen Gastropoda) keine Protonephridien inden Larven zur
Ausbildung kommen (vgl. H. HOFFMANN, 1951: 181); die Protonephridien fehlen
aber bezeichnenderweise auch den Larven der Plathelminthes, Nemertini, Sipuncu-
lida, Brachiopoda, Bryozoa und Deuterostomia! Die dazu im starken Gegensatz
hervortretende Ausbildung larvaler Excretionsorgane bei Annelida, bei nicht-marinen
Gastropoda, bei den meisten Bivalvia und bei einigen anderen Gruppen kann mit
REMANE (1967: 604) als unabhángig entstanden beurteilt und muss als Convergenz
erklart werden.

Besondere Erwáhnung verdient weiterhin, dass den meisten dieser ursprtinglichen
Larven (Epimenia, Halomenia, Acanthochiton, Chiton, Patella, Dentalium, Nucula,
Yoldia) ein Enddarm fehlt, und erst während der Metamorphose verbindet sich das
Rectum mittels Durchbruch mit dem bestehenden Mitteldarm. Diese späte Anlage bei
Mollusca ebenso wie bei Nemertini (!) lasst im Sinne der ‘Biogenetischen Regel’ auf
afterlose Ahnen ähnlich den Turbellarien schliessen, --- wogegenbei den der gemein-
samen Wurzel morphologisch nicht mehr so nahestehenden Annelida sowie den weiteren
Mollusca der Enddarm bereits genetisch stärker fixiert ist und daher in der Anlage
auch ontogenetisch vorgezogen wird.

Schliesslich ergeben sich durch den Bildungsmodus des Nervensystems phylo-
genetische Hinweise. Bisher nur für die Chitonen gewürdigt (vgl. HANSTRÖM, 1928;
KORSCHELT, 1936), werden bei Solenogastren-Larven die beiden paarigen Längs-
bahnen ebenfalls als caudale Auswüchse des cerebralen Zentrums angelegt. Dieser
mit den Placophora übereinstimmende Bildungsmodus gewinnt bei einem Blick auf
die Verhältnisse bei Turbellarien und Nemertinen besondere Bedeutung: Auch bei
diesen Gruppen werden die Längsnervenstränge durch caudades Auswachsen ohne
direkte Beziehungen zum Ectoderm angelegt, --- nicht aber durch lokale Einwucherung
wie bei Annelida und Conchifera. Daraus lasst sich zumindest ablesen, dass die mor-
phologische Entfernung der Aculifera zu den Turbellaria/Nemertini bedeutend geringer
ist, als diejenige der Conchifera und Annelida (dass die Aculifera sich also bezüglich
des Nervensystems direkt von turbellariomorphen Ahnen ableiten lassen). Angesichts
der Tatsache, dass auch bei einem hochentwickelten Solenogaster (Neomenia carinata)
die beiden ventralen (nicht aber lateralen) Nervenbahnen schon durch Einwucherung
gebildet werden, muss für diesen abgeleiteteren Modus eine dreifache (!) Convergenz
festgestellt werden. Diese Parallelbildungen lassen sich jedoch mit HAMMERSTEN &
RUNNSTRÖM (1925: 312, 1926: 50) zwanglos derart erklären, “dass zunächst eine
Konzentration von Nervenzellen in den Marksträngen zu Ganglien stattgefunden hat,
wonach diese auf verkürzte Weise durch lokale Wucherungen ihre Entwicklung genom-
men haben.”

Im adulten Zustand lasst sich jedoch innerhalb der Aculifera für das Nervensystem
weniger Übereinstimmung erkennen, besonders was die irreführende Bezeichnung
‘Amphineura’ betrifft, denn weder Solenogastres noch Caudofoveata zeigen eine typische
Amphineurie als zwei getrennte Paare von Marksträngen; wohl aber sind solche Ver-

háltnisse innerhalb der Conchifera bei Tryblidiacea, Pedalmarkstránge auch bei vielen
Dementsprechend grenzt der morphologisch gut
fundamentierte Begriff Aculifera die drei Klassen Solenogastres, Caudofoveata und

Gastropoda-Diotocardia ausgebildet.

SALVINI-PLAWEN

Placophora deutlich gegentiberstellend von den Conchifera ab.

Die Verwandtschaftsbeziehungen der Caudofoveata und Solenogastres sind hiermit
grossteils aufgedeckt, und nach der Organisation im Rahmen der funktionellen Mor-
phologie ergeben sich sowohl ftir die Caudofoveata und Solenogastres innerhalb der
Weichtiere (Abb. 4) eindeutige phylogenetische Rückschlüsse, wie sich auch die Mollus-

DISCUSSION

ken insgesamt in das stammesgeschichtliche Bild (Abb. 15) einfügen.

Die in Abb. 15 skizzierten Verhältnisse lassen sichin einigen unsicher erscheinenden
Punkten durch folgende Beziehungen untermauern:

Die Ableitung der Metazoa aus den Protozoa erfolgt im Anschluss an IVANOV
(1968); ‘Phagocytella’ (oder ‘Parenchymella’) stellt hierbei ein hypothetisches
Zwischenstadium dar (vgl. auch METSCHNIKOFF, 1886: 145-159).

Die Ableitung der Hydrozoa aus der Scyphozoen-Wurzel, unddiese wiederum aus
den Anthozoen-Ahnen wird durch die Ursprünglichkeit der Anthozoa eindeutig
unterstützt: Die Radidr-Symmetrie muss secundár sein, da sich die Bilaterie
der Anthozoen nur von einer freibeweglichen (kriechenden) Ausgangsform ver-
stehen lasst; die Polypen-Form stellt gegenüber der Meduse den ursprünglicheren
Typus dar, da einerseits die Anthozoen keinen Hinweis auf Medusen geben, und
andererseits die Entwicklungsvorgánge auch verschiedentlich darauf hinweisen
(vel. z.B. WERNER, 1966: 346); der Differenzierungsgrad der Nesselkapsel-
Typen nimmt (von gruppenspezifischen Sonderbildungen abgesehen) deutlich von
Anthozoe zu Scyphozoa und Hydrozoa zu (vgl. BOUILLON & LEVI, 1967; 454-
455); die Mittelschicht (Stiltzlamelle, Mesogloea) kann zwanglos als zusehends
vereinfachtes Mesenchym (Ecto-Mesoderm) aufgefasst werden, welches bei den
Anthozoa noch am deutlichsten zur Ausbildung kommt.

Die acoelomaten Kamptozoa (Entoprocta) zeigen in den Larven der urspriing-
licheren Loxosomatidae (JAGERSTEN, 1964; FRANZEN, 1967) homoiologe Ver-
háltnisse zu den Weichtieren, wodurch die Gruppe náher an die Mollusken ge-
bunden wird: die funktionelle und morphologische Ähnlichkeit dieser Kamptozoen-
Larven durch die medioventrale, bewimperte Kriechsohle (Fuss) mit Schleim-
driisen, durch die Peripedal-Furche und durch den ‘Mantel’ mit Falte lasst auf
einen gemeinsamen turbellariomorphen Ausgangspunkt der Gruppe mit den Mol-
lusken schliessen, welcher bei den Kamptozoen nur secundär durch den Ubergang
zur Sessilitát differenziert wurde.

Die coelomaten Echiurida zeigen durch die starken Ubereinstimmungen in der
Entwicklung mit den Anneliden einerseits (Spiralfurchung, Borstenbildung), durch
das interkalare Wachstum des imaginalen Rumpfabschnittes (einheitliches Coelom,
ohne Teloblastie!) andererseits, dass sie kurz vor der Articulaten-Differen-
zierung abgezweigte ‘Protanneliden’ darstellen (vgl. KORN, 1960). Die atavisti-
schen Verhältnisse der Mesoderm-Ausbildung beim Bonellia-Weibchen (ohne
Coelom, nur Muskulatur und Mesenchym) entsprechen hierbei in etwa noch den
Zustánden vor der phylogenetischen Coelom-Differenzierung (vgl. Mollusca).
Die coelomaten Sipunculida zeigen durch Furchung, Bildung des Nervensystems
und andere ontogenetische Merkmale deutliche Beziehungen zum Anneliden-
Zweig, unterscheiden sich aber einschneidend durch das Fehlen von Coelom-
Metamerie (keine Teloblastie!). Die schizocoele Coelombildung und die Larven-
Entwicklung wiederholen hingegen noch Zustánde vor der phylogenetischen
Coelom-Differenzierung (vgl. HATSCHEK, 1884; HYMAN, 1959; AKESSON, 1958;
JAGERSTEN, 1963). Das allgemeine Fehlen von Protonephridien und die Hüll-
glocke (‘Serosa’-Zellen) der Sipunculus-Larve einerseits, wie die (stark verkürzte)
Kriechsohle mit Drüse (‘lip-gland’) der Pelagosphaera-Larven andererseits,
belegen zudem die gemeinsame turbellariomorphe Wurzel mit den Mollusken-
Vorfahren.

f) Die schon früher vorgenommenen Versuche, die Tentaculata an die Sipunculida

zu náhern (Coelom-Anordnung, etc.) haben durch das Auftreten der Spiralfurchung
bei Phoronidea (RATTENBURY, 1954) einen eindeutigen Beleg erfahren, wodurch
der Anschluss an die coelomaten Spiralia gegeben ist (vgl. auch SIEWING, 1967:
141, 165).

Die Chaetognatha stellen im Hinblick auf ihr Nervensystem einwandfrei Gastro-

212 PROC. THIRD EUROP. MALAC. CONGR.

neuralia mit Zygoneurie dar, auch wenn die larvale Urmund-Region zum
Kórperende der heranwachsenden Tiere wird (vgl. aber unten). Die eindeutigen,
ontogenetischen Beziehungen zu den Tentaculata-Brachiopoda (zweiteiliges
Coelom, etc.) bekráftigen zudem die weitere Verwandtschaft mit dieser Gruppe
und machen eine Stellung der Chaetognatha innerhalb der Deuterostomia un-
haltbar!

h) Der Anschluss der Deuterostomia oder Notoneuralia selbst an Gastroneuralia
oder Protostomia hat primár in den Coelom-Verháltnissen zu den Tentaculata
eine deutlichere Beziehung (als sog. “Archicoelomata”, vgl. SIEWING, 1967);
das Fehlen von Protonephridien in den Larven weist auf die Spiralia-Wurzel hin
(vgl. р 210). Doch lassen sich die durch die zeitliche Entwicklungsdistanz
verwischten Übergänge von Spiraliern zu Deuterostomiern unschwer ablesen:
Die Deuterostomie stellt an sich kein abtrennendes Merkmal dar, sind doch
auch die ‘protostomen’ Nematomorpha und andere Formen wie Viviparus (Gastro-
poda), u.a.m. deuterostom (vgl. auch SIEWING, 1967: 145)! Die enterocoele
Coelombildung lasst sich zwanglos als ein zeitliches Vorziehen der Coelom-
Formierung aus dem aequivalenten Zellmaterial in der Spiralia-Larven ver-
stehen (vgl. KORSCHELT, 1936: 113); diese Formierung erscheint daher gegeniiber
der Schizocoelie lediglich stark verkürzt und auf das Wesentliche beschränkt
(‘rationalisiert’), zudem natürlich auch modifiziert (zeitliche Spanne und morpho-
logischer Abstand). Vermittelnde Verhältnisse zeigensichjabei den Tentaculata
(vgl. RATTENBURY, 1954: 326-331; HARTMAN, 1963).

Das dorsale Nervensystem (Notoneurie), mit einem Nervengeflecht schon bei
den protostomen Phoronidea entwickelt, zeigt sichja nur bei den hochentwickelten
Chordonia in tatsächlich allein notoneuraler Ausbildung; sowohl die Enterop-
neusta, wie die Pterobranchia weisen ein Übergangsstadium in Form von Strang-
verdichtungen sowohl in der Dorsomediane wie in der Ventromediane auf! Die
mit den Tentakeln als dorsal orientierten Pogonophora (Herz = dorsal) lassen
ebenfalls ein ventrales Nervensystem feststellen. So erscheint also die Notoneurie
als solche allein bei den Chordonia fixiert, wogegen die noch mehr basal stehenden
Gruppen der Pentacoela (Enteropneusta, Pterobranchia und Pogonophora mit
fünf Coelomhöhlen) jede Anschlussmöglichkeit offen lassen.

Letztlich bleiben also die Coelom-Bildungsverhältnisse für die Ableitungs-
Beziehungen am deutlichsten bestimmend; durch den (mit dem Übergang zur
Sessilität) rückgebildeten Kopf-Abschnitt der Tentaculata kann allein deren phylo-
genetische Wurzel auch als Ausgangsbasis für die Deuterostomier-Entwicklung
angenommen werden.

Als Modell für die Phylogenie der Deuterostomier selbst mag die Abbildung 21
bei REMANE (1967: 644) die Beziehungen verdeutlichen, wobei die Pogonophora
im Sinne JÄGERSTEN’s mit dorsalen Tentakelkrone angenommen und als echte
Pentacoela aufgefasst werden.

Die gewonnenen Erkenntnisse und Correlationen lassen nun zusammenfassend im
Überblick feststellen, dass den meist stark vernachlässigten Solenogastres und
Caudofoveata jeweils eine Organisation zukommt, welche im Rahmen der Mollusca
allgemein verschiedene Fragen und Probleme in ein neues Licht rücken. Besonders
an den herausgegriffenen Organsystemen der Muskulatur, des Darmtraktes, des
Coeloms und der Ontogenie wird deutlich, dass speziell der stammesgeschichtliche
Fragenkreis aufschlussreich aufgehellt wird. Umso nachteiliger wirktes sich aus und
umso bedauerlicher ist die Tatsache, dass das jahrzehntelange Desinteresse an
diesen Gruppen eine unbearbeitete Materialfülle hat anhäufen lassen, welche mit der
Wiederaufnahme der Studien nur schrittweise bearbeitet und ausgewertet werden kann.

Als Folge der Ausführungen braucht wohl nicht mehr im Detail betont zu werden,
dass jegliche morphologisch-phylogenetische Discussion über Mollusken ohne eine
Berücksichtigung von Solenogastres und von Caudofoveata falsche Voraussetzungen
bringt; die angebliche Metamerie der Tryblidiacea gibt ein deutliches Beispiel hierfür.
Aber auch in der vergleichenden Anatomie der Weichtiere erweisen sich die Vertreter
der beiden Klassen als aufschlussreich, und widerlegen die häufige Sinngebung, dass
Mollusca und Conchifera identisch wären (Conchifera als “true molluscs” bei FRETTER
& GRAHAM, 1962: 9), --- denn nicht die Artenzahl, nicht die Häufigkeit und nicht die
Popularität legen hier die wissenschaftliche Bedeutung einer Tiergruppe dar, sondern
allein die Organisation und der morphologische Aufbau!

SALVINI-PLAWEN

COELOMATA
DEUTEROSTOMIA ARTHROPODA
TENTACULATA CHAETOGNATHA ANNELIDA.
ARTICULATA

SIPUNCULIDA ECHIURIDA ;

COELOMATA

ANTHOZOA SCYPHOZOA HYDROZOA

CNIDARIA

CTENOPHORA

213

AMERA

CONCHIFERA

PLACOPHORA

SOLENOGASTRES

CAUDOFOVEATA

gleitend

ACULIFERA KAMPTOZOA

NEMERTINI
INTHES

PLATHELMINTHES

gleitend

TURBELLARIOMORPHE
~ BILATERIA

PORIFERA

gleitend

'PHAGOCYTELLA'

PROTOSPONGIA - TYPUS

PROTOZOA

ABB. 15. Stammesgeschichtliche Entwicklungs-Beziehungen der recenten Tiergruppen (Die Lángen der
Ableitungsstriche sind raumbedingt und sollen nicht morphologische Entfernungen ausdrilcken.).

214 PROC. THIRD EUROP. MALAC. CONGR.

ZUSAMMENFASSUNG

Anhand eines Organisations-Abrisses für die beiden Klassen Solenogastres und Caudofoveata werden

einige phylogenetisch bedeutungsvolle Merkmalskomplexe herausgegriffen und dargelegt:

1. Die serial angeordnete Dorsoventral-Muskulatur bildet einerseits den Ausgangspunkt einer sich
zunehmend verdichtenden Concentration der Stränge über Placophora- und Tryblidiacea- bis zu den
weiteren Conchifera-Verhältnissen, und lasst andererseits, leicht den stammesgeschichtlichen An-
schluss an turbellariomorphe Ahnen erkennen.

2. Der Divertikeldarm bei Solenogastres ist als für die Mollusken ursprünglich aufzufassen und lasst
sich ebenfalls aus einer turbellariomorphen Wurzel ableiten.

3. Lebensweise und Radula-Bau geben im Zusammenhang mit der Lokomotionsfrage deutliche Belege
für die von den Ahnen ererbte acoelomate Organisation des Molluskenstammes.

4. Die Annahme von der ursprünglichen Zweizahl der Ctenidien bei Mollusken wird durch die Verhält-
nisse bei Caudofoveata gestützt.

5. Die Hüllglocken-Larve der Solenogastres und Bivalvia-Protobranchia muss als ein tief in den stam-
mesgeschichtlichen Entwicklungsvorgängen verwurzelter Typus aufgefasst werden: das Fehlen von
Protonephridien bei Aculifera (und weiteren Gruppen), die späte Enddarm-Anlage und der Modus der
Bildung des Nervensystems unterstützen in eindeutiger Weise diese Annahme.

6. Der morphologische Wert der Vertreter beider Klassen sollte nicht durch deren geringe Artenzahl
übersehen werden.

SUMMARY

The phylogenetical importance of both classes, the Solenogastres as well as the Caudofoveata, is pointed

out by means of several characteristics of their organization:

1. The former term ‘Aplacophora’ states only the same level of organization and cannot be upheld further:
the Caudofoveata have to be separated from the Solenogastres and placed (besides the Placophora)
as a third class within the Mollusca-Aculifera.

2. The numerous serially-arranged dorsoventral muscles as in the recent Solenogastres represent the
starting point of an increasing concentration within the molluscs which extends as a continuous
sequence over the Placophora and Tryblidiacea to the remaining Conchifera.

3. The relationship of musculature and diverticular digestive tract between Platyhelminthes and Soleno-
gastres leads to a turbellariomorphic ancestor for the molluscs.

4. The manner of living compared with the anatomy of the radular apparatus shows in connection with
the problem of locomotion that the mollusc stem originated from an acoelomate organization.

5. The original number of two ctenidia within the mollusc stem is supported by the conditions in the
Caudofoveata.

6. The Testcell-larva of Solenogastres and Bivalvia-Protobranchia (and partly as well as those of Scapho-
poda) has to be considered phylogenetically as a strongly fundamented type which belongs at the very
root of the Spiralia. This statement is supported by the lack of protonephridia within the primitive
representatives (Turbellaria, Nemertini, Aculifera, Sipunculida), by the retardedanlage of the rectum
within most of these larvae, and by the manner of the development of the larval nervous system within
Aculifera as well as Turbellaria and Nemertini.

7. The adult situation of the nervous system within Solenogastres and Caudofoveata does not correspond
with the term ‘Amphineura’, which therefore has to be replaced by ACULIFERA (HATSCHEK, 1891).
The amphineury within the conchiferous tryblidiacea (Neopilina) supports this conception.

8. The enormous morphological value of the representatives of both classes, Solenogastres as well as
Caudofoveata, should not be neglected simply because of the relatively low number of species.

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MALACOLOGIA, 1969, 9(1): 217-242
PROC. THIRD EUROP. MALAC. CONGR.
ZUR MOLLUSKENFAUNA DES FELSLITORALS BEI ROVINJ (ISTRIEN)
Ferdinand Starmühlner

1. Zoologisches Institut
der Universitit Wien
Wien 1, Osterreich

EINLEITUNG

Angaben tiber das Vorkommen und die Verteilung von Mollusken der Adria, bzw.
der Nord-Adria wurden in der álteren Literatur ausschliesslich von Konchyliologen
gemacht, u.a. von STOSSICH (1865), WEINKAUFF (1866/67), CARUS (1889/93) und
BRUSINA (1896). Die ersten ökologischen und biologischen Angaben über Adria-Tiere
(darunter auch von Mollusken) stammen von LORENZ (1863), weiters von WIMMER
(1883), der vor allem Notizen über das Tiefenvorkommen adriatischer Konchylien
machte. ZIMMERMANN (1907) beschrieb im Adria-Führer die Lebensräume der
häufigsten Küstenmollusken.

Eine Zusammenstellung aller im Golf von Triest (Nord-Adria) gefundenen Mollus-
ken, mit kurzen Angaben über ihr Vorkommen gab GRAEFFE (1903), einen weiteren
Beitrag zur Kenntnis der nordadriatischen Küsten-Molluskenfauna leistete ODHNER
(1914) mit zahlreichen biologischen und ökologischen Bemerkungen aus dem Raum von
Rovinj. Aus dem Gebiet von Rovinj stammen auch die ausführlichen Bodenunter-
suchungen von VATOVA (1928). Neben anderen Meerestieren wurdenin diesen
langjährig durchgeführten Aufsammlungen auch die Mollusken berücksichtigt, deren
Verteilung, Häufigkeit und Vergesellschaftung nach Dredschnetz-Proben ermittelt
wurde. KÜHNELT (1930, 1933, 1938, 1942 und 1950) führte eingehende Studien über
die Bohrmuscheln des felsigen Küstenlitorals von Rovinj durch. Eine umfassende
Liste von 913 in der Adria gefundenen Molluskenarten (bzw. Unterarten) verfasste
COEN (1937). Von den genannten Arten (bzw. Unterarten) entfallen 10 auf die Placo-
phora, 560 auf die Gastropoda (davon 450 Prosobranchia, 100 Opisthobranchia und 10
Pulmonata), 320 auf die Bivalvia und 23 auf die Cephalopoda.

LELOUP & VOLZ (1938) veröffentlichten eine umfassende Monographie der Placo-
phora der Adria. Sie enthält umfassende systematische, anatomische, biologische und
ökologische Angaben über diese Tiergruppe. Ein Verzeichnis der häufigsten Mollus-
ken-Arten des adriatischen Litorals (mit besonderer Berücksichtigung von Aufsamm-
lungen aus dem Gebiet von Rovinj), kurze Notizenüber Vorkommen und Biologie finden
sich in der von RIEDL (1963) herausgegebenen FAUNAUND FLORA DER ADRIA in der
Bearbeitung der Mollusca von STARMÜHLNER.

MATERIAL UND SAMMELMETHODE

Das in dieser Studie dargestellte Material von Mollusken aus dem Felslitoral bei
Rovinj (Tafel 1) stammt von Aufsammlungen, die während der Exkursionen des 1.
Zoologischen Institutes der Universität Wien an dasInstitut za Biologiju Mora während
der Jahre 1953 bis 1967, also innerhalb von 14 Jahren in den Sommermonaten durch-
geführt wurden. Als Aufsammler betätigten sich neben dem Autor noch die Mit-
arbeiter des 1. Zoologischen Institutes, vor allem die Herren Dr. Heinz SPLECHTNA,
Univ. Prof. Dr. Rupert RIEDL, Dr. Eduard PIFFL, weiters Frau Univ. Prof. Dr.
Anneliese STRENGER, sowie die Teilnehmer der Meeresbiologischen Kurse der Uni-
versität Wien. Letztere waren in Arbeitsteams eingeteilt, die unter der Leitung der

(217)

218 PROC. THIRD EUROP. MALAC. CONGR.

ISTRIEN

TAFEL 1. Die istrianische Küste bei Rovinj sowie die umliegenden Inseln und Buchten.

STARMUHLNER 219

ТАЕЕГ 2. Verteilung der einzelnen Grössenklassen von Littorina neritoides im Supralitoral: I =
Gezeitenmittelniveau (GM) - 56 Ind., dchschn. H.: 2'6 mm; Ц = 100 cm oberhalb GM - 56 Ind., dchschn. H.:
6’4 mm; Ш = 200 cm oberhalb GM - 54 Ind., dchschn. H.: 8'15 mm.

genannten Damen und Herren die einzelnen litoralen Lebensrdume besammelten.

Die Aufsammlungen wurden zum Grossteil mit der freischwimmenden Tauchmethode
(siehe RIEDL 1953, 1954, 1966; STARMUHLNER 1955a, b, 1968), d.h. mit Flossen,
Tauchglas und Schnorchel durchgefúhrt. Nur tiefere Proben unter 10-15 m wurden
vom Schiff aus mit Bodenschleppnetzen, Dredschen oder bei Weichbóden mit Boden-
greifern entnommen. Bei quantitativen Aufsammlungen wurden in der Regel Proben
von einem oder mehreren gleichfSrmigen Probenquadraten von 1/16m? Fläche (25 cm
Seitenlinge) entnommen. Bei diesen Proben-Entnahmen arbeiteten mindestens 2,
meist aber 3 oder 4 Taucher zusammen. Ein Taucher bestimmte mit dem Proben-
quadrat die zu besammelnde Fläche, dienach Bestimmungder Lage, Tiefe, Exposition,
Höhe und Zusammensetzung des Pflanzenbewuchses (oder Bewuchses durch sessile
Tierformen, wie Spongiaria, Hydrozoa, Anthozoa, Bivalvia, Ascidiau. dgl.) abgesammelt
wurde.

Der abgetragene Aufwuchs mit der aufsitzenden oder dazwischen lebenden Mikro-
und Mesofauna (zu letzterer zählt die überwiegende Mehrzahl der Mollusken!) wurde
von einem zweiten Taucher in einen knapp daruntergehaltenen Plastiksack gefüllt,
wobei geachtet wurde, dass keine grösseren Stücke abgetragenen Materials weg-
geschwemmt wurden. Um auch die Bewohner des in Kalkfelsen reich entwickelten
Endolithions in die Probenaufsammlung zu bekommen, wurde mitHammer und Meissel
auch das Felsgestein bis etwa 5-10 cm Tiefe abgetragen, soweit als Bohrgänge von
Muscheln und Bohrschwämmen feststellbar waren.

Die derart aufgesammelten Proben wurden anschliessend im Labor des Institut za
Biologiju Mora aufgearbeitet. In der Regel wurde zuerst die Methode der Klima-
verschlechterung angewendet, d.h. die Probe kam in ein grosses Glasaquarium,
wurde vollkommen mit Wasser bedeckt und so aufgestellt, dass eine Ecke dem Ta-
geslicht ausgesetzt war. Die baldige Verschlechterung des Wasserklimas (0, -Mangel)

220

PROC. THIRD EUROP. MALAC. CONGR.

TAFEL 3

Molluskenleitformen des Supra-, Eu- und Sublitorals (inklusive Höhlen) primärer
Hartböden.

Allgem. Abkürzungen: W.Z. = Weisse Zone; H. = Halophytenzone; S.Z. = Schwarze
Zone; F.T. = Fluttümpel; Sp.T.: Spritzwassertümpel; F. = Flutniveau; MW =
Mittelwasserniveau der Gezeiten; E. = Ebbeniveau.

Pflanzen- und Tiernamenabkürzungen: Li.ne. = Littorina neritoides; Pa.lu.: Patella
lusitanica; Br.mi. = Brachyodontes minimus; Pa.coe.: Patella coerulea; Mi.ca. =
Middendorfia caprearum; Mo.tu. = Monodonta turbinata; Pi.ma.: Pisania maculosa;
Ga.du. = Gastrochaena dubia; O.ed.: Ostrea edulis; Li.li. = Lithophaga lithophaga;
Bo.mi.: Bosellia mimetica; Ca.l. = Callochiton laevis; Mu.b.: Murex blainvillei;
Ca.d’o. = Cantharus d’orbigny; Pe.a. = Peltodoris atromaculata; P.fi. = Petrosia
ficiformis; P.sq.: Peyssonnelia squamaria; Ha.tu. = Halimeda tuna.

221

STARMUHLNER

104011915

18401113

222 PROC. THIRD EUROP. MALAC. CONGR.

zwingt vagile Tiere, darunter vor allem Kleingastropoden (Rissoidae, Bittium, Tro-
chidae, Buccinidae u.a., viele Opisthobranchia) und manche kleine vagile Bivalvia
(wie Musculus) an die Oberfläche zur Lichtseite, wo sie leicht mit Pinzette oder
Pipette abgesammelt werden können. Später wurde der Rest des Materials unter dem
Binokular nach lebenden Mollusken ausgesucht. Nach der Fixierung des Materials mit
Seewasser-Formol erfolgte in der Regel nach Ausschútteln der Probe ein zweites
Aussuchen, um eventuell tibersehene Kleinstschalen zu bekommen.

DIE MOLLUSKENGESELLSCHAFTEN DER EINZELNEN KUSTENZONEN

Die Aufsammlungen im Ktistenlitoral erstreckten sich auf folgende Küstenzonen
(Tafel 3):

1) Supralitoral: Küstenstreifen über der Flutlinie des Eulitorals, soweit der
Einfluss des Meeres durch Wellenschlag noch jenen des Landes deutlich úber-
wiegt. Die Höhenerstreckung schwankt je nach dem Expositionsgrad zwischen
25 cm und tiber 10 m (RIEDL 1963):

a) Primärer Hartboden
b) Sand, -Kiesktiste

2) Eulitoral: Küstenstreifen zwischen der Ebbe- und Flutlinie, die Gezeitenzone
(intertidal), deren Breite in der Nord-Adria ca. 50 cm erreicht und nur bei
sehr flachem Kiistenwinkel wesentlich breiter werden kann (RIEDL 1963):

a) Primärer Hartboden (Epi- und Endolithion).

3) Sublitoral: Schliesst unter der Ebbelinie dem Eulitoral an und stellt im
Bereich der seichten Nord-Adria den stándig untergetauchten Abschnitt der
Küstenabböschung dar (RIEDL 1963):

a) Primärer Hartboden
а’) Epilithion
a’’ ) Endolithion
b) Höhlen mit Epi- und Endolithion
c) Rollblöcke (Felsgeröll und -blöcke im Bereich des Küstenlitorals, die
je nach Grösse von den Wasserströmungen häufiger oder seltener um-
gelagert (gerollt) werden (RIEDL 1966).
d) Phytalbewuchs auf primären Hartböden:
d’ ) Cystoseira-Bestände
e) Anschüttungsböden auf primären Hartböden:
e’ ) Mischböden mit vorherrschendem
Porifera (meist Geodia) -Bewuchs
Ascidia-Bewuchs
Vidalia volubilis-Bewuchs
e”? ) Sekundäre Hartböden: Bryozoa-Bestände (vorherrschend Hip-
podiplosia-, Myriozoum-, Retepora- und Flustra-Arten) auf
Schellmaterial (mit leeren Schalen von Pectinacea, Veneracea,
Limidae, Cardiacea u.a. Bivalvia) sowie flächiger Kalkalgen
(meist Lithothamnium- Arten).
f) Reine Sedimentböden:
f’ ) Sandböden
г’) Posidonia-, Zostera-Bestände auf Sandbóden
f’’’) Phytallose Schlamm- und Tonböden

1) Supralitoral (Tafel 3)

Die Grenzen des Supralitorals werden durch die Ktistenneigung und Exposition
bestimmt. Die Wirkung des Wellenschlages reicht von wenigen Zentimetern (z.B. an

STARMUHLNER 223

geschtitzten Stellen im Limski-Kanal) bis zu maximal 10 m tiber dem Gezeitenmittel-
wasser (=GM) auf pelagischen Inseln (z.B. an der dem Schirokko-Wind nach SSW ex-
ponierten Ktiste der Insel Banjole). Bei sehr flachen Ktistenabschnitten kónnen die
Wellen auslaufen oder sie kippen über. Bei steiler Küstenneigung geht die Orbital-
bewegung der Wasserteilchen allmáhlich in eine Pendelbewegung úber, wobei das
Maximum der Höhenwirkung bei einer Neigung von etwa 30° eintritt. Der Einfluss von
Spritz- und Sprühwasser reicht bei starkem Wellenschlag wesentlich höher als der
der fliessenden Woge. Vongrosser Bedeutungfür die Ausbreitung des Supralitorals ist
ausserdem die Neigung zum Sonneneinfall, da starke Erhitzung an Südhängen zur Aus-
trocknung der für das Supralitoral kennzeichnenden Blaualgen führt.

a) Primärer Hartboden

Von der Flutlinie lassen sich gegen die Halophytenzone zu im Supralitoral der
Felsküste der Nord-Adria zwei Zonen unterscheiden:

Die Schwarze oder Lithophyten-Zone: Charakterisiert durch endolithische Blaualgen,
wie Mastigocoleus testarum, Hyella caespitosa, Entophysalis granulosa u.a., sowie die
braunschwarze Flechte Lichina confinis. Der genannte Bewuchs bewirkt die dunkle,
“schwarze” Färbung des Kalkgesteines. An exponierten Stellen mit starker Besied-
lung durch die Seepocken Chthamalus stellatus stellatus und Ch. st. depressus.

Die Weisse Zone: Starke Abnahme der Blaualgen, dadurch Hervortreten des hellen
Kalkgesteines, auf dem die gelborange Flechte Caloplaca aurantia siedelt.

Am Unterrand der Schwarzen Zone, deren Breite bis 2 m über dem GM betragen
kann, finden sich zahlreiche Fluttümpel ausgewaschen, während in der “Weissen Zone,”
deren Ausdehnung bis 5 m über der Schwarzen Zone, bzw, 2 bis 6 m über dem GM
betragen kann, Spritzwassertümpel auftreten.

Die Charakterart des Supralitorals ist unter den Mollusken Littorina neritoides (L.),
deren Verbreitung von der Gezeitenmittellinie bis zur oberen Grenze der “Weissen
Zone” reicht, um die sich die Halophytenzone anschliesst. Auf SSW exponierten
Abböschungen (z.B. auf der Insel Banjole) mit einer Neigung von ca. 30° reicht die
Art von der Gezeitenmittellinie bis ca. 3 m-5 m oberhalb in die “Weisse Zone.” An
der Grenze zwischen Eu- und Supralitoral (Gezeitenmittelwasser bis Flutlinie) finden
sich ausschliesslich juvenile, dunkel pigmentierte Individuen, während gegen die Spal-
ten des Supralitorals (Übergang zwischen “Schwarzer” und “Weisser” Zone) die Indi-
viduenzahlen pro Flächeneinheit allmählich ab-, die Grössen der Individuen dagegen
zunehmen. Die Schalen nehmen eine kalkweisse Färbung an, was auf den allmählichen
Verlust des schützenden, dunklen Periostrakums der älteren Individuen zurückzuführen
ist. Folgende Tabelle gibt eine Zusammenstellung von Auszählungen pro 1/16 m? an
der SSW-Küste der Insel Banjole (15. Juli 1967):

25 cm oberhalb des GM 135 Ind./1/16m2 (z.T. in leeren Balaniden-
Gehäusen)
50cm oberhalb des GM 50 Ind./1/16m? (in Löchern und Spalten)
100 cm oberhalb des GM 9 Ind. /1/16m2 (in flachen Vertiefungen)
100cm oberhalb des GM 75 Ind. /1/16m2 (in tiefer Rinne)
200 cm oberhalb des GM vereinz. Ind. /1/16m2 (in Spalten u. dgl.)
300 cm oberhalb des GM die letzten Tiere (in Spalten u. dgl.)

Die Tabelle zeigt, dass die Tiere in der “trockenen” sog. “Weissen Zone” tagsüber,
während der starken Einstrahlung, truppweise in Spalten, Löchern zusammengeballt
sind (Tafel 6, Abb. 1), während sie auf den freien Flächen fehlen. Sie wandern mit
zunehmendem Alter vom Gezeitenniveau, wo sich die Larven festsetzen, gegen die
“Schwarze” und “Weisse” Zone. Tafel 2 zeigt eine graphische Darstellung der Ver-
teilung der einzelnen Grössenklassen von Littorina neritoides (Tafel 6, Abb. 2) aus

224 PROC. THIRD EUROP. MALAC. CONGR.

dem Gezeitenmittelniveau (I), 100 cm oberhalb des GM (II) und 200 cm oberhalb des
GM (Ш).

An der unteren Grenze des Supralitorals tiberschneidet sich das Vorkommen von
Г. neritoides mit der Obergrenze des Vorkommens von Patella lusitanica GMELIN.

Die Flutttimpel an der Grenze zwischen Eu- und Supralitoral werden im Gezeiten-
wechsel stándig mit frischem Seewasser erneuert. Daher sind sie von den gleichen
Tieren besiedelt, die in dieser Zone auftreten, abgesehen von grósseren, freischwim-
menden Organismen. An Algen werden - z.B. in den Fluttümpeln der Insel Banjole -
Lyngbyia confervoides, Chaetomorpha aerea und Cladophora pellucida, sowie Fosliella
sp. und Lithophyllum sp. als krustenförmige Überzüge festgestellt. Vereinzelt treten
auch Ulva lactuca, Polysiphonia sertularoides, Acetabularia mediterranea und ver-
kümmerte Cystoseiva sp. -Büschel auf.

Die Fluttümpelränder sind von Littorina neritoidesbesetzt, daneben Patella lusitanica
in höher, Patella coerulea L. intiefer gelegenen Tümpeln. Von den typischen Eulitoral-
bewohnern gelangen die Placophoren Middendorfia caprearum (SCACCHI) und Chiton
olivaceus SPENGLER indie Fluttümpel, wo sie vor allem flache Vertiefungen besiedeln.
Von den Gastropoda tritt gelegentlich Monodonta turbinata (BORN) auf, während die
Bivalvia durch Brachyodontes minimus (POLI), Mytilus galloprovincialis LAM.,
Ostrea edulis L. im Epilithion und Gastrochaena dubia (PENNANT) (Tafel 8, Abb. 2)
im Endolithion vertreten sind.

In die Spritzwassertümpel im Bereich der “Weissen Zone” gelangt Meerwasser nur
durch auslaufende Wellen und einfallende Gischt. Mit wachsendem Abstand vom
Meer werden die Bedingungen extremer. Vorallem wirkt sich die starke Einstrahlung
und die dadurch bedingte hohe Temperatur sowie das Ansteigen des Salzgehaltes durch
Verdunstung und Eindickung begrenzend für die Besiedlung von Meeresorganismen
aus. Trotzdem findet man pflanzliche Besiedlung von Blau- und Grünalgen, Flagellaten
und Diatomeen. Von den Mollusken findet sichnur Littorina neritoides an den Tümpel-
rändern, vereinzelt auch knapp unter der Wasseroberfläche.

b) Sand- und Kiesküste

Diese Formation ist bei Rovinj nur in wenigen Buchten, so bei der sog. Saline am
Eingang des Limski-Kanal ausgebildet. In den Lückenräumen tritt in durchfeuchteten
Abschnitten Truncatella subcylindrica (L.), seltener Alexia myosotis (DRAPARNAUD)
auf.

2) Eulitoral (Tafel 3)
a) Primärer Hartboden

Das GM zwischen Ebbe- und Flutlinie wird in der Nord-Adria, wie im gesamten
Mittelmeer, durch die Pferdeaktinie Actinia equina (L.) gekennzeichnet, die hier ihr
Hauptvorkommen zeigt. Die für die Fluttümpel genannten Algen treten im ganzen
Eulitoral auf. Weiters finden sich im stark bewegten Wasser an häufigeren Arten:
Nemalion helminthoides, Laurencia obtusa, Enteromorpha-Arten, Padina pavonia,
Corallina mediterranea und Jania rubens. Im unteren Bereich des Eulitorals schliessen
bereits die Braunalgenbestánde des hochwüchsigen Phytal mit Cystoseiva mediter-
тапеа, С. barbata und Sargassum-Arten an. Seltener sind bei Rovinj (z.B. auf der
Leuchtturm-Insel Sv. Ivan na Puëini) Kalkalgenbánke, sog. Trottoir’s, ausgebildet. Sie
werden vor allem von Lithothamnium- und Corallina-Arten aufgebaut.

Unter den Mollusken treten die in den Fluttümpeln erwähnten Arten im Eulitoral
besonders auffällig in Erscheinung. Unter der Placophora finden sich Middendorfia
caprearum und Chiton olivaceus regelmässig, während unter den Gastropoda Patella
lusitanica mit der höheren Schale im Bereichzwischen GM und Flutgrenze, die flachere

STARMUHLNER 225

Patella coerulea dagegen zwischen GM und Ebbelinie sitzt. Typische Bewohner sind
weiters Monodonta turbinata, Pisania maculosa (LAM.) - letztere vor allem bei Auf-
treten von Ulva-Bestinden - Columbella rustica (L.) und vereinzelt Conus ventri-
cosus GMELIN. Während die erstgenannte Art Algenschaber ist, zählen Pisania
und Columbella zu den saprophagen Formen und Conus jagt nach Nereiden.

Unter den Bivalvia finden sich in kleinen Spalträumen Brachyodontes minimus und
unter der Ebbelinie Mytilus galloprovincialis. Ostrea edulis besiedelt exponierte,
stark umspülte Felspartien, wo sich auch vereinzelt Chama gryphoides (L.) und Ch.
gvyphina (LAM.) finden. Im Endolithion des Eulitorals ist vor allem Gastrochaena
dubia (Tafel 8, Abb. 2) an stark exponierten und umspülten Flächen in grosser Dichte
anzutreffen, wobei die verkalkten Siphonen ihre Lage anzeigen. Daneben finden sich
Petricola lithophaga RETZIUS, sowie die Löcher von Lithophaga lithophaga (L.),
deren Hauptverbreitung im unteren Eulitoral liegt und vom Algenaufwuchs der Felsen
abhängig ist. In Corallina mediterranea-Beständen ist die Muschel Musculus mar-
moratus (FORBES) gelegentlich anzutreffen.

Abschliessend lässt sich sagen, dass für das Eulitoral der nordadriatischen Fels-
küste folgende Molluskenvergesellschaftungen typisch sind (Tafel 3):

Placophora: Middendorfia caprearum - Chiton olivaceus - Assoz.

Gastropoda: Patella lusitanica - P. coerulea - Monodonta turbinata - Pisania
maculosa - Assoz. mit Columbella rustica und Conus ventricosus.

Bivalvia: Brachyodontes minimus - Mytilus galloprovincialis - Ostrea edulis
- Chama gryphoides - Assoz. im Epilithion und mit einer Gastro-
chaena dubia - Lithophaga lithophaga - Assoz. im Endolithion,
vereinzelt Petricola lithophaga.

3) Sublitoral
a) Primärer Hartboden

An exponierten Steil- und Überhängen, besonders an N-exponierten Küstenab-
böschungen, tritt der höherwüchsige Algenbewuchs, das eigentliche Phytal, der sonst
in der Regel an die untere Eulitoralgrenze anschliesst, etwas zurück. Neben krusten-
bildenden Kalkalgen, wie Lithophyllum incrustans, L. vacemus und Pseudlithophyllum
expansum treten auffälliger höchstens Cladophora sp.-Bestände,Corallina mediterranea
und Codium bursa auf. Daneben wird die Felsoberfläche hauptsächlich von Schwäm-
men, wie Cacospongia scalaris, Halichondria panicea, Dynamena cavolinii ua. Arten,
von Hydrozoen, wie Aglaophenia pluma und Bryozoen, wie Schizoporella sanguinea

überzogen.
Unter den Mollusken treten von den eulitoralen Formen unter den Gastropoda die
Patella-Arten und Monodonta turbinata allmählich zurück. Columbella rustica,

Pisania maculosa, gelegentlich Cerithium rupestre RISSO in grösserer Zahl und
vereinzelt Diodora graeca (L.) sind neben kleinen Muriciden, Cantharus d’orbigny
(Tafel 6, Abb. 4), die stets, aber meist vereinzelt auftreten, für das obere, bebrandete
Sublitoral typisch. Wesentlich individuenreicher sind an exponierten Felsen sessile
Bivalvia, wobei vor allem Mytilus galloprovincialis und Ostrea edulis in Nestern
auftreten. Im Endolithion erreicht an derartigen Standorten Lithophaga lithophaga,
mit 10-20 Ind./1/16m2 hohe Individuendichten, während Gastrochaena dubia (Tafel 8,
Abb. 2) und Petricola lithophaga etwas zurücktreten,

Die primären Hartböden des Sublitorals sind an Standorten mit niederwtichsiger
Schattenalgen-Vegetation und Bewuchs sessiler Tierarten durch folgende Mollusken-
Vergesellschaftungen charakterisiert:

Epilithion:
Gastropoda: Columbella rustica - Pisania maculosa - Cerithium rupestre -

226 PROC. THIRD EUROP. MALAC. CONGR.

Assoz. mit Diodora graeca, Cantharus d’orbigny u. selteneren

Arten.
Bivalvia: Mytilus galloprovincialis - Ostrea edulis - Assoz.
Endolithion:
Bivalvia: Lithophaga lithophaga - Assoz. mit vereinzelten Gastrochaena dubia

und Petricolä lithophaga.
b) Höhlen (Tafel 3)

Einen besonderen Lebensraum stellen die Brandungshöhlen im Bereich des felsigen
Küstenlitorals dar. RIEDL (1966) definiert eine Meereshöhle topographisch als “ganz
oder teilweise unter der Wasserlinie gelegene und von genügend beständigen Teilen des
Felslitorals grossteils umschlossene Räume ab einem Volumen von 1 m3, deren Ein-
gangsweite die Innenweite gewöhnlich nicht übertrifft, dennoch aber eine zureichende
Kommunikation mit dem offenen Meer bietet” (S. 108). Derartige Höhlen sind an der
Felsküste von Rovinj z.B. am sog. Stadtfelsen unterhalb des Leuchtturmes der Stadt
und - als Grotte - auf der Insel Banjole ausgebildet. Gegen die schattigen bis licht-
losen Teile der Höhle nimmt der Algenbewuchs des primären Hartboden allmählich
ab und geht in einen Bewuchs sessiler Tierartenüber (Porifera, Cnidaria, Balanidae,
Bivalvia, Ascidia, sessile Polychaeten u.a.) über. Die Höhleneingänge sind je nach Be-
lichtungsverhältnissen-von Schattenalgen, wie Halimeda tuna, Peyssonnelia squamaria
und gegen die inneren Flächen zu mit krustigen Kalkalgen wie Pseudlithophyllum expan-
sum u.a. Arten bewachsen. Die grünen, flachen Thalli von Halimeda sind häufig von
Bosellia mimetica (Tafel 7, Abb. 1) einer Sacoglossa besiedelt, die in Färbung und
Körperform einen Thallus von Halimeda imitiert. Auf den roten, polsterförmigen
Peyssonnelia- und den krustenförmigen Pseudlithophyllum- Beständen sind dagegen die
ebenfalls rot gefärbten Placophora Callochiton laevis (MONTAGU) und Chiton coral-
linus RISSO anzutreffen. Im Innern der Höhlen dominieren sehr häufig Schwämme als
Bestandbildner, darunter Chondrosia reniformis, Hemimycale sp., Mycale massa,
Anchinoe sp., Cacospongia scalaris, Ircinia-Arten, Petrosia ficiformis u.a. Arten,
weiters Hydrozoen-Kolonien von Plumularia sp., Aglaophenia sp., Anthozoen-“Wiesen”
mit Epizoanthus sp. oder Parazoanthus axinellae.

Auch von den sessilen Bivalvia treten an denHöhlenwänden an gut bespülten Wänden
im Epilithion einige Arten als Bestandsbildner auf, vor allem Ostrea edulis und Arca
lactea. Im Endolithion dominiert wieder Lithophaga lithophaga, seltener Gastrochaena
dubia (Tafel 8, Abb. 2) und Petricola lithophaga. In kleinen Hohlräumen sitzt
häufig Beguinea calyculata (L.). Unter den Gastropoda finden sich in den Höhlen-
beständen, bedingt durch das Fehlen der Algen, nur mehr saprophage, karnivore Arten,
darunter einige Spezialisten. So sind vor allem die Muricidae vertreten, mit Arten
wie Muricidea blainvillei (PAYRAUDEAU), Tritonalia edwardsi (PAYRAUDEAU) und
Tritonalia aciculata (LAM.), seltener findet sich Murex trunculusL. Vonden Buccinidae
ist vor allem Cantharus d’orbigny (Tafel 6, Abb. 4), von den Nassidae Nassa reticulata
und von den Toxoglossa Conus ventricosus anzutreffen. An den Höhlenwänden
sitzen ausserdem stets die Gehäuse von Vermetus-Arten. Unter den Spezialisten sei
vor allem Peltodoris atromaculata BERGH (Tafel 7, Abb. 2) erwähnt, die sich aus-
schliesslich auf dem Schwamm Petrosia ficiformis findet, der die Nahrung dieser
Dorididae bildet.

Die Mollusken- Vergesellschaftungen in den Meereshöhlen bei Rovinj sind durch
folgende Arten zu charakterisieren (Tafel 3):

Epilithion:
1) Nordexponierte Überhänge, Höhleneingänge:
a) auf Halimeda tuna: Bosellia mimetica
b) auf Peyssonnelia squamaria und Kalkalgen:
Callochiton laevis - Chiton corallinus - Assoz.

STARMUHLNER 227

2) Höhlenwände im licht- und phytalfreien Bereich:

Gastropoda: Muricidea blainvillei - Tritonalia edwardsi -
Cantharus d’orbigny -Assoz. mit Vermetus-Arten.

Bivalvia: Ostrea edulis - Arca lactea -Assoz.

3) Auf Drusen des Schwammes Petrosia ficiformis:
Peltodoris atromaculata

Endolithion:
Von den Eingängen bis zu den inneren Höhlenwänden:

Lithophaga lithophaga - Gastrochaena dubia -Assoz.
mit Petricola lithophaga, Beguinea calyculata.

с) Rollblöcke

An den Grenzen des Felslitorals zu den Anschüttungsböden treten bei Rovinj häufig
Geröll- und Blockfelder auf. RIEDL (1966) gibt auf S. 56 in der Tabelle 2 eine Über-
sicht über die Grössenordnungen von Rollblöcken in Beziehung mit ihrer mittleren
Liegezeit und den geschätzten Umrollungen pro Jahr (mobiles Substrat). So liegen
nach seinen Berechnungen grosse Felsblöcke von 5 bis 10 m Durchmesser wahr-
scheinlich 10-15 Jahre bis sie einmal vollständig oder teilweise umgerollt werden.
Sie zeigen an ihrer Oberfläche die typischen Phytalbestände des besonnten, primären
Felslitorals, an ihren Seitenwänden Phytal-Schattenalgen und an hohl liegenden Unter-
seiten typische Höhlenbestände. Auch ihre Molluskenfauna setzt sich aus den gleichen
Arten wie im einheitlichen Felslitoral zusammen.

Blöcke unter 2 m Durchmesser haben dagegen in der Regel nur mehr eine Lie-
gezeit unter einem Jahr und werden z.B. bei einem Dchm. von 1 m ca. einmal pro
Jahr umgerollt. Geröll mit 10 cm Durchmesser wird dagegen durchschnittlich bis
24 mal im Jahr gewendet! Die Besiedlung dieser Rollblöcke kann daher nur durch
raschwüchsige und kurzlebige sessile Arten erfolgen, wiez.B. durch die Algen Lyngbya
sp., Acetabularia mediterranea und Melobesia sp., die Bryozoe Lichenopora radiata
und den Anneliden Spirorbis pagenstecheri. Unter den Mollusken, welche vor allem
die Unterflächen von Rollblöcken besiedeln, sind von den Placophora Chiton olivaceus,
Acanthochiton communis (RISSO), A. fascicularis (L.), sowie Lepidopleurus cajetanus
(POLI) typisch, während unter den Gastropoda Haliotis lamellosa LAM. dominiert.
Seltener, aber stets anzutreffen sind Diodora gibberula (LAM.) und D. graeca (L.),
Emarginula-Arten, kleine Muricidae, Buccinidae, sowie, festsitzend, Capulus hungari-
cus (L.). Von den Bivalvia finden sich neben Chama-Arten und Anomia ephippium
im Epi-, Lithophaga lithophaga, Gastrochaena dubia (Tafel 8, Abb. 2) und Petricola
lithophaga im Endolithion.

Epilithion:
Placophora: Chiton olivaceus - Acanthochiton - Lepidopleurus
cajetanus - Assoz.
Gastropoda: Haliotis lamellosa - Diodora - Emarginula -Assoz.
mit Capulus hungaricus u.a. Arten.

Bivalvia: Anomia ephippium - Chama - Assoz.
Endolithion:
Bivalvia: Lithophaga lithophaga - Gastrochaena dubia -Assoz.

mit Petricola lithophaga.
d) Phytalbewuchs auf primären Hartböden (Tafel 4)

Das hochwüchsige Phytal im besonnten freien Sublitoral der primären Hartböden
wird bei Rovinj fast ausschliesslich von Cystoseira-Arten bestimmt. Es treten dabei
u.a. Cystoseira spicata, C. adriatica, C. abrotanifolia, C. crinita und C. corniculata
auf, und zwar reinwüchsige und gemischte Bestände. Je nach Lage des Standortes
wirken sich die Schwingungen des Brandungshorizontes mehr oder weniger stark auf
die Sedimentationsverhältnisse in den Beständen aus. Bei starker Wasserbewegung,

228

PROC. THIRD EUROP. MALAC. CONGR.

TAFEL 4

Molluskenleitformen des Phytalbewuchses auf primären Hartböden (Cystoseira sp.-
Bestand mit Halimeda tuna, Digenea simplex, Udotea petiolata (als Beispiel neben
anderen Arten) und Hydrozoenstöckchen im Unter- und Zwischenwuchs.

Tiernamenabkürzungen: Ca.ex. = Cantharidus exasperatus; Ri.va. = Rissoa vari-
abilis; Bi.re. = Bittium reticulatum; El.vi. = Elysia viridis; Co.ve. = Conus ventri-
cosus; Ac.co. = Acanthochiton communis; Tr.ac. = Tritonalia aciculata; Id.co.:

Idulia coronata; Mu.ma. = Musculus marmoratus.

Bi.re

STARMUHLNER

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230 PROC. THIRD EUROP. MALAC. CONGR.

wie z.B. in reinen С. spicata -Bestánden, finden sich nur gröbere Schellpartikel,
dagegen findet keine Schlamm - oder Detritusabsetzung statt, Epiphyten- und Epizoen-
Aufwuchs ist gering oder fehlend, die Fauna auffallend artenarm.

Bei schwacher Wasserbewegung - wie z.B. in Cystoseiva abrotanifolia - С. crinita -
Mischbestánden - wirken die Büschel der Braunalgen als Sediment- und Detritusfänger.
Es kommt zum schichtenförmigen oder unregelmässigen Ablagern von Sediment-
material, sowie zu starkem Epiphyten- und Epizoen-Auf - und Zwischenwuchs. Ein
engverzweigtes Lückenraumsystem ermöglicht das Vorkommen einer artenreichen,
vagilen Kleinfauna. Unter den Gastropoda finden sich spezielle Ernährungstypen:
Aufwuchsäser (Diatomeenfresser), wie Rissoacea, kleine Trochidae, Bittium reticu-
latum DA COSTA; Algensauger, wie die Sacoglossa Elysia viridis (MONTAGU) und
Thuridilla splendida (Tafel 7, Abb. 4); Saprophage, wie Columbella rustica, Pisania
maculosa; Rauber, wie Conus ventricosus.

Unter den Epiphyten der Cystoseira-Büscheln treten u.a. folgende Arten besonders
in Erscheinung: Botryocladia botryoides, Laurencia sp., Jania rubens, Ceramium sp.
in den distalen Verzweigungen, Kalkalgen, wie Fosliella sp. als Krusten auf den Stämm-
chen und Acetabularia sp., Dictyota sp., Halimeda tuna, Peyssonnelia squamaria und
Sargassum sp. in den schattigen Bodenpartien. Zwischen den Cystoseira-Beständen
siedeln häufig mehrjährige Padina pavonia-Büschel. Dazu kommt ein dichter Diato-
meen-Aufwuchs auf den verzweigten Algenfäden.

Im Tieraufwuchs, vor allem an den Stämmchen in Bodennähe, finden sich Porifera,
Bryozoa, wie Amanthia-, Membranipora-, und Scrupocellaria-Arten, sowie Stöckchen
von Hydrozoen. Sind letztere reichlich ausgebildet, so sind stets auch Aeolidiacea,
die sich von ihnen ernähren, anzutreffen. Gelegentlich wurden dabei folgende Arten
festgestellt: /dulia coronata (GMELIN), Flabellina affinis (GMELIN) (Tafel 7, Abb. 5),
Calmella cavolini (VERANY), Coryphella lineata (LOVEN), Trinchesia foliata (FORBES
& GOODSIR), Favorinus branchialis (RATHKE), Facelina drummondi (THOMSON),
Hervia peregrina (GMELIN) und Spurilla neapolitana (DELLE CHIAJE).

Am Kalkalgenaufwuchs der Stämmchen (Fosliella sp.) sitzen vereinzelt Placophora,
wie Chiton olivaceus und Acanthochiton communis; von den Gastropoda kann verein-
zelt Haliotis tuberculata in juvenilen Exemplaren vorhanden sein. Massenvorkommen
zeigen in den Cystoseiren die aufwuchsäsenden Prosobranchia. Unter ihnen dominiert
Rissoa variablis (у. MUHLFELD) (Tafel 6, Abb. 3), Alvania cimex (L.), Bittium
reticulatum DA COSTA, Cantharidus exasperatus (PENNANT), С. striatus (L.),
Calliostoma laugieri (PAYRAUDEAU) und Gibbula varia (L.). Vereinzelt finden sich
Tricolia pulla (L.) und T. speciosa (v. MUHLFELD). Unter den sparophagen, gelegent-
lich auch karnivoren Arten sind Columbella rustica, Pisania maculosa, Cantharus
d’orbigny (Tafel 6, Abb. 4), Туйопайа aciculata, Muricidea blainvillei und Tritonalia
edwardsi vereinzelt anzutreffen. Zu den seltenen Formen zählen Fusus- und Mitra-
Arten, Pusia tricolor (GMELIN), sowie Murex trunculus L.; Conus ventricosus ist
stets vertreten.

In einem, mit Epiphyten stark durchwachsenen Cystoseira-Mischbestand fanden
sich nach quantitativen Aufsammlungen durchschnittlich 7-8 Ind. von Bittium reticu-
latum, 3-5 Ind. von Rissoa variabilis (Tafel 6, Abb. 3), 2-3 Ind. von Alvania cimex,
1-2 Ind. von Cantharidus-Arten, 1-2 Ind. von Columbella rustica, 1-2 Ind. von Conus
ventricosus und 1 Ind. von Tritonalia aciculata auf je 1/16 m? besammelter Fläche.
Die übrigen, vorher genannten Arten traten nur sporadisch und nicht in jeder Probe
auf. Die durchschnittliche Individuendichte betrug für Mollusken 25-26 Ind./1/16 m2
Cystoseira-Büschel, davon ca. 23-24 Prosobranchia, der Rest Bivalvia, Placophora
oder Opisthobranchia.

Die Bivalvia sind im hochwüchsigen Phytal spärlich vertreten. Der dichte Zwischen-
wuchs ermöglicht den Filtrierern nur kümmerliche Entwicklung. Nur kleine Arten,

STARMUHLNER 231

die Spalträume ausnützen können, treten auf, wie Musculus marmoratus (FORBES)
(Tafel 8, Abb. 3) und an Standorten in der Náhe des Eulitorals gelegentlich auch
Brachyodontes minimus und in Spalten zwischen Kalkalgen und Epizoen Beguinea
calyculata.
Die Cystoseira-Bestände des Phytals lassen sich nach Dominanz und Frequenz der
gefundenen Mollusken wie folgt charakterisieren (Tafel 4):
Placophora: Chiton olivaceus - Acanthochiton communis -Assoz.
auf dem krustigen Kalkalgenwuchs der Stammchen.
Gastropoda: Bittium reticulatum - Rissoa variabilis - Alvania
cimex -Assoz. mit Cantharidus-Arten, Columbella
rustica, Conus ventricosus, Tritonalia aciculata,
Elysia viridis, Thuridilla splendida u.a. Arten. Ве
Hydrozoen-Zwischenwuchs mit Aeolidiacea, wie
Idulia coronata, Flabellina affinis, Calmella cavolini,
Coryphella lineata, Trinchesia foliata, Favorinus
branchialis, Facelina drummondi, Hervia peregrina
und Spurilla neapolitana.
Bivalvia: Musculus marmoratus-Brachyodontes minimus-
Assoz. mit Beguinea calyculata.

e) Anschüttungsböden (Tafel 5)

Auf den Anschüttungsböden, welche die primären Hartböden überlagern, lassen
sich in der Nord-Adria bei Rovinj einerseits Mischböden, andrerseits Sekundäre
Hartböden unterscheiden.

Die Mischböden, die sich aus Schell, verschlammten Sand mit dazwischen auf-
wachsenden Sedentariern und Krustenalgen zusammensetzen, werden häufig durch das
Überwiegen bestimmter Auf- und Zwischenwuchs-Sedentarier gekennzeichnet. Bei
Rovinj finden sich -in Tiefen zwischen 20 und 30 m - Mischböden mit vorherrschendem
Porifera-Bewuchs (vor allem Geodia cydonium, mit einem Dchm. bis 80 cm) und
vorherrschendem Ascidia-Bewuchs (Phallusia mamillata, Ascidia virginea, A. men-
tula, Aplidium conicum, Distoma adriaticum u.a. Arten). Auf bestimmten Mischböden
dominiert die Rotalge Vidalia volubilis in dichten Beständen. Selbstverständlich finden
sich auch alle Übergänge zwischen den genannten Typen der Mischböden.

Auf den Geodia-Mischböden, z.B. NO der Insel Banjole in ca. 33 m Tiefe, bewirkt
die rückläufige Küstenkonvektions-Strömung einen feinen Detritusstrom zum Meeres-
boden und begünstigt die Entwicklung sessiler Strudler und Filtrierer.

Die Aszidien-Mischböden finden sich dagegen mehr auf den leicht geneigten
Anschüttungsflächen mit verschlammtem Sand, bei schwacher Strömung, z.B. N der
Figarole-Inseln in ca. 25 m Tiefe. Beide Mischböden zeigen in Dredschnetz-Proben
viel Schellmaterial, hauptsächlich von Muscheln aus Sedimentböden. Ihre Schale dient
vielen Sedentariern als Anheftungsfläche. Zu denhäufigsten ArtendesSchells zählen
Pecten jacobaeus L., Chlamys- und Lima-Arten, Pitaria chione (L.), Venus verrucosa
(L.) und andere Veneridae, sowie Cardiacea. Gelegentlich treten die genannten Arten
in den Fängen auch in lebenden Exemplaren auf. Im Sediment ist lebend stets
Cardium exiguum GMELIN und Nucula nucleus (L.) vertreten. Unter den Gastropoden
tritt hier von den grösseren Arten vor allem Aporrhais pes pelecani (L.) (Tafel 6,
Abb. 5), sowie Cerithium vulgatum BRUGUIERE, seltener Cassidaria echinophora (L.)
in Erscheinung. Die letztgenannten Arten finden sich auch auf grossen, mit Algen und
Schwämmen bewachsenen Schellteilen, daneben Murex trunculus L., Diodora italica.
(DEFRANCE), Astraea rugosa (L.), Calliostoma conulus (L.) und C. zizyphinus (L.).
Unter den sessilen Prosobranchia sind Vermetus-Arten, Capulus hungaricus,
Calyptraea sinensis (L.), sowie Crepidula-Arten (Tafel 8, Abb. 1) stets auf Schell und

232

PROC. THIRD EUROP. MALAC. CONGR.

TAFEL 5

Molluskenleitformen der Abschüttungsböden auf primären Hartböden (Schlamm-,
Sand-, Misch- und Sekundäre Hartböden).

Pflanzen-, und Tiernamenabkürzungen: Tu.co. = Turritella communis; So.va. =
Solen vagina; De.de. = Dentalium dentale; Act.to. = Actaeon tornatilis; Te.di. =
Tellina distorta; Vi.vo. = Vidalia volubilis; Al.c. = Alvania cimex; Ap.p.p. = Aporrhais
pes pelecani; Ar.n. = Arca noae; Bou.au. = Bouvieria aurantiaca; Pha.ma. = Phallusia
mamillata; Ca.hu. = Capulus hungaricus; Ar.tu. = Archidoris tuberculata; Ge.cy. =
Geodia cydonium; Tr.ad. = Trivia adriatica; Hi.fo. = Hippodiplosia foliacea.

STARMUHLNER 233

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234 PROC. THIRD EUROP. MALAC. CONGR.

Kalkalgenkrusten zu finden. Auch Placophora treten hier regelmássig auf. Unter
den Opisthobranchia treten die Doridaceae vor allem auf Schwammböden auf, am auf-
fälligsten sind dabei Archidoris tuberculata CUVIER (Tafel 7, Abb. 3) und Dendrodoris
limbata (CUVIER), wáhrend die Pleurobranchidae mehr Aszidiengrtinde bevorzugen,
als die auffállig orangerote Bouvieria aurantiaca (RISSO).

Von den sessilen Bivalvia sind auf den Mischböden die Arca-Arten mit Arca поае L.,
A. barbata L. und Arca lactea (Tafel 8, Abb. 1) sowie Modiolus barbatus (L.) besonders
haufig. Lebend treten aber auch, wie bereits erwáhnt, die frei schwimmenden
Chlamys- und Lima-Arten (Tafel 8, Abb. 4) auf.

Bei Uberwiegen des Bewuchses durch die Rotalge Vidalia volubilis, z.B. im Val di
Lone (S der Katharinen-Insel) in 14 m Tiefe, treten wie im Phytal des Felslitorals,
aufwuchsäsende Arten in Erscheinung wie Alvania cimex und Bittium reticulatum,
daneben finden sich wieder Cerithium vulgatum und С. rupestre sowie vereinzelt
Murex trunculus. Von den Opisthobranchia tritt Polycera quadrilineata (MULLER)
und Glossodoris gracilis (RAPP) auf, wihrend im Sediment neben Philine aperta (L.)
die sandbewohnenden Muscheln Cardium exiguum und Nucula nucleus stets in grósserer
Individuenzahl gefunden werden. Auf dem Schell siedeln zwischen Vidalia-Büscheln
Arca noae, A. lactea und Modiolus barbatus.

Zur Charakterisierung der Mischböden bei Rovinj lassen sich folgende Leitformen
anführen (Tafel 5):

Geodia-, Ascidia-, Vidalia-Mischböden:

Placophora: Auf Kalkalgen (Lithothamnium u.a.):

Chiton corallinus - Callochiton laevis -Assoz.

Gastropoda: Cerithium vulgatum - Aporrhais pes pelecani -
Assoz. mit Murex trunculus, Diodora italica,
Astraea rugosa, Vermetus-Arten, Calyptraea
sinensis, Capulus hungaricus, Archidoris
tuberculata, Dendrodoris limbata, Bouvieria
aurantiaca ч.а. selteneren Arten.

Bivalvia: Im Schell leere Schalen von Pecten jacobaeus,
Chlamys-, Lima-, Cardium-Arten, Pitaria
chione, Venus verrucosa u.a. Veneridae.

Im Sediment: Cardium exiguum - Nucula nucleus
ASSOZ.
Auf Schell, Kalkalgen, Aszdien u.dgl.:
Arca noae - Modiolus barbatus -Assoz.
Auf Vidalia volubilis:

Gastropoda: Alvania cimex - Bittium reticulatum -Assoz.
mit Cerithium rupestre, C. vulgatum, Murex
trunculus, Polycera quadrilineata, Glossodoris
gracilis u.a. selteneren Arten.

Die Sekundären Hartböden bilden sich auf Mischböden aus Schellmaterial, das durch
Kalkalgen, Schwämme und aufwachsende, stöckchenbildende, verkalkte Bryozoen, wie
Hippodiplosia-, Myriozoum-, Retepora-, Flustra-u.a. Arten verbunden wird. Die Kalk-
algen sind vorwiegend durch Lithothamnium-Arten repräsentiert, während sich der
Schell hauptsächlich aus den leeren Schalen der bereits bei den Mischböden auf-
gezählten Muscheln zusammensetzt. Auch die Vergesellschaftungen der Mollusken
zeigen eine ähnliche Zusammensetzung wie auf den Mischböden, wobei allerdings
sessile Formen dominieren:

Gastropoda: Capulus hungaricus - Calyptraea sinensis -
Assoz. mit Murex trunculus, Diodora italica,
Astraea rugosa, Cerithium vulgatum, Trivia

STARMUHLNER 235

TAFEL 6
ABB. 1. Littorina neritoides in Felsspalten des Supralitorals (Foto: M. Wimmer-
Mizzaro).
ABB. 2. Verschiedene Grössenstufen von Littorina neritoides (Foto: М. Wimmer-
Mizzaro).

ABB. 3. Rissoa variabilis (Foto: M. Wimmer-Mizzaro).
ABB. 4. Cantharus d’orbigny (Foto: H. Splechtna).
ABB. 5. Aporrhais pes pelecani (Foto: H. Splechtna).
ABB. 6. Trivia adriatica (Foto: M. Wimmer-Mizzaro).

236 PROC. THIRD EUROP. MALAC. CONGR.

adriatica (MONTEROSATO) (Tafel 6, Abb. 6),
Calliostoma-Arten und Archidoris tuberculata.

Placophora und Bivalvia sind mit den gleichen Arten wie auf
den Mischbóden vertreten.

f) Reine Sedimentböden (Tafel 5)

Bei Rovinj finden sich reine Sedimentböden nur an wenigen Küstenflächen. Es han-
delt sich dabei um Seeböden, die durch Anschüttung entstanden sind. Man kann sie
nach Zusammensetzung und Korngrössen der beteiligten Sedimente in Geröll-Schotter-
Schell-Sand-Schlamm-Tonböden ordnen. Die oberen Schichten werden je nach ihrer
Exposition und Korngrösse durch die Wasserbewegungen mehr oder weniger um-
geschichtet. Die Mollusken der Gerölle und Schotter (Rollblockfelder), sowie der
Schellböden (Mischböden) wurden bereits besprochen. Die feineren Sedimentböden
können bei Rovinj in Sand- und phytallose Schlamm- und Tonböden unterteilt werden.

Sandböden finden sich bei Rovinj zwischen dem Punta Corrente und der Roten Insel
(Isola Rossa oder Crveni Otok), sowie NO der Konverzada-Insel in der Bucht von
Kuvi. Diese Böden sind zum Teil von Seegras-Beständen aus Zostera marina oder
Posidonia oceanica bewachsen.

SALVINI-PLAWEN (1968) untersuchte die interstitielle Kleinfauna der groben und
mittelfeinen Sande bei Rovinj und fand in den Proben folgende Mollusken, deren Nach-
weis zum Grossteil neu für die Nord-Adria war:

Grobsande:
Placophora: Lepidopleurus cancellatus (SOWERBY),
L. intermedius SALVINI-PLAWEN.

Gastropoda: Prosobranchia: Caecum glabrum (MONTAGU)
Opisthobranchia: Microhedyle milaschewitchii
(KOWALEVSKY), М. glandulifera (KOWALEVSKY),
Pseudovermis papillifera KOWALEVSKY, P. schulzi
MARCUS & MARCUS, Hedylopsis spiculifera
(KOWALEVSKY), Philinoglossa helgolandica
HERTLING, Tergipes despectus (JOHNSTON),
Embletonia pulchra (ALDER € HANCOCK).

Mittelfeine Sande:

Gastropoda: Opisthobranchia: Microhedyle glandulifera(KOWALEVSKY),
M. lactea (HERTLING).

In der makroskopischen Molluskenfauna der Sandböden dominieren die sandbohrenden
Bivalvia, Scaphopoda, sowie sandgrabenden Prosobranchia, wie ráuberische Майса-
und saprophage Nassa-Arten, sowie grabende Cephalaspidea unter den Opistho-
branchia (Tafel 5):

Gastropoda: Prosobranchia: Natica millepunctata LAM. -
Nassa mutabilis (L.) -Assoz. mit Polynices
guillemini (PAYRAUDEAU), Nassa neritea (L.).
u. selteneren Arten.

Opisthobranchia: Actaeon tornatilis (L.) -
Bulla striata- Assoz. mit Philine aperta,
Haminea hydatis (L.), Retusa-Arten, Scaphander
lignarius (L.), Aglaja depicta RENIER u.a.
Cephalaspidea.

Scaphopoda: Dentalium dentale L. - Dentalium vulgare
DA COSTA -Assoz.

Bivalvia: Tellina distorta (POLI) (Tafel 8, Abb. 5) -
Divaricella divaricata (L.) -Assoz. mit Solen

STARMUHLNER 237

TAFEL 7
ABB. 1. Bosellia mimetica (Foto: M. Wimmer-Mizzaro).
ABB. 2. Peltodoris atromaculata (Foto: M. Wimmer-Mizzaro).
ABB. 3 Archidoris tuberculata(Foto: М. Wimmer-Mizzaro).
АВВ. 4. Thuridilla воре: (Foto: М. Wimmer-Mizzaro).
ABB. 5. Flabellina affinis (Foto: M. Wimmer-Mizzaro).

238 PROC. THIRD EUROP. MALAC. CONGR.

vagina L., Pinna nobilis L. (meist zwischen
Seegras-Beständen!), Chlamys-, Cardium-Arten
(darunter Cardium exiguum, C. tuberculatum),
Venus gallina L., Pitaria-, Venerupis-Arten,
Mactra stultorum (L.), Donax trunculus L.,
Psammobia depressa (PENNANT), Solenocurtus
strigillatus (L.), Arcopagia balaustina (L.),
Gastrana fragilis (L.), Macoma tenuis (DA COSTA),
Angulus planatus (L.), A. incarnatus (L.), Pharus
legumen (L.), Ensis ensis (L.) und Е. siliqua (L.).

Auf den Seegräsern dominieren unter den Mollusken wieder die aufwuchsäsenden
Formen der Prosobranchia, wie Rissoacea, kleine Trochidae und Bittium reticu-
latum. In der Wurzelregion treten auch grössere Arten, wie Cerithium rupestre,
Columbella rustica und Conus mediterraneus auf. Unter den Opisthobranchia ist auf
den Seegrasblättern die winzige, flachgedrückte Runcina coronata (QUATREFAGES)
sowie Elysia viridis anzutreffen. Bivalvia sind nur durch kleine, sessile Arten am und
zwischen dem Kalkalgen- und flächigen Bryozoenaufwuchs der Wurzelregion ver-
treten, wie Arca lactea (Tafel 8, Abb. 1), Modiolus barbatus, Brachyodontes minimus
und - eingebohrt - Gastrochaena dubia.

Gastropoda: Alvania cimex - Bittium reticulatum -Assoz.
mit Gibbula varia, Cantharidus striatus, versch.
Rissoacea, Cerithium rupestre, Columbella rustica,
Conus ventricosus, Runcina coronata, Elysia
viridis.

Bivalvia: Arca lactea - Modiolus barbatus -Assoz. mit
vereinzelten Brachyodontes minimus, Gastro-
chaena dubia.

Phytallose Schlamm- und Tonböden sind bei Rovinj in der Bucht des Val di Bora, N
des Institut za Biologiju Mora, sowie im Limski-Kanal ausgebildet. Während die
erstgenannte Bucht eine Tiefe von ca. 18 m erreicht, betrágt sie im Limski-Kanal
bei Sotto Castello bis 32m. Unterden Prosobranchia dominieren schlammbohrende
Arten, wie Turritella communis RISSO und Turritella triplicata (BROCCHI), Natica-
und Polynices-Arten, Aporrhais pes pelecani (Tafel 6, Abb. 5) und Nassa-Arten.
Opisthobranchia wurden bisher sehr selten gefunden und zwar ausschliesslich leere
Schalen von Cephalaspidea. Die Scaphopoda zeigen mit Dentalium-Arten einen
hohen Anteil in den Proben, ebenso die in Weichböden eingegrabenen Bivalvia, wie
Tellina-Arten (Tafel 8, Abb. 5), Venus casina L., Cardium paucicostatum SOWERBY,
Aloidis gibba (OLIVI), sowie die Protobranchia-Gattungen Nucula und Leda. Pla-
cophora fehlen den feinen Sedimentböden (Tafel 5):

Gastropoda: Turritella - Aporrhais pes pelecani -ASSoz. mit
Natica- und Polynices- und Cythara-Arten,
Strombiformis subulata (DONOVAN), Melanella
aycuata (LEACH), Chrysallida interstincta
(MONTAGU), Eulimella acicula (PHILIPPI),
Turbonilla lactea (L.) und Murex brandaris L.

Scaphopoda: Dentalium dentalium - D. panormitanum -Assoz.

Bivalvia: Solen vagina - Cardium paucicostatum - Aloidis
gibba -Assoz. mit Nucula nucleus, Leda fragilis
(CHEMNITZ), Venus casina, Tellina-Arten,
Abra alba (WOOD), u.a. selteneren Arten.

ABB.
ABB.
ABB.
ABB.
ABB.

op wo

STARMUHLNER 239

TAFEL 8

Arca lactea mit Crepidula sp. aufsitzend (Foto: M. Wimmer-Mizzaro).

Gastrochaena dubia im aufgeschlagenen Felsgestein des Eulitorals (Foto: M. Wimmer -Mizzaro)
Gruppe von Musculus marmoratus an Algen sitzend (Foto: M. Wimmer-Mizzaro).

Lima inflata (Foto: M. Wimmer-Mizzaro).

Tellina distorta mit ausgestreckten Siphonen (Foto: M. Wimmer-Mizzaro).

240 PROC. THIRD EUROP. MALAC. CONGR.

ZUSAMMENFASSUNG

Im Bereich des Felslitorals, sowie küstennaher Anschüttungsböden der istrianischen Westküste bei
Rovinj wurden durch mehrere Jahre (1953-1967) qualitative undquantitative Aufsammlungen von Mollusken
durchgeführt.

1. Supralitoral:

a. Primärer Hartboden: Littorina neritoides-Patella lusitanica-Assoz.
b. Sand-Kiesboden: Truncatella subcylindrica-Alexia myosotis-Assoz.
2. Eulitoral:
a. Primärer Hartboden:
Placophora: Middendorfia caprearum-Chiton olivaceus-Assoz.
Gastropoda: Patella (lusitanica, coerulea)-Monodonta turbinata-Pisania maculosa-Assoz. mit
Columbella rustica und Conus ventricosus.
Bivalvia: Brachyodontes minimus-Mytilus galloprovincialis-Ostrea edulis-Chama (gryphoides,
&vyphina)-Assoz. im Epilithion und Gastrochaena dubia-Lithophaga lithophaga-Assoz. im
Endolithion, vereinzelt Petricola lithophaga.

3. Sublitoral:
a. Primärer Hartboden (Felslitoral):
Epilithion:

Gastropoda: Columbella rustica-Pisania maculosa-Cerithium rupestre-Assoz. mit verein-
zelten Diodora graeca, Cantharus d’orbigny, u.a. selteneren Arten.

Bivalvia: Mytilus galloprovincialis-Ostrea edulis-Assoz., mit Chama-Arten.

Endolithion:
Bivalvia: Lithophaga lithophaga-Gastrochaena dubia-Assoz. mit Petricola lithophaga.
b. Höhlen:

Höhleneingänge, Nordexponierte Überhänge: Auf Halimeda tuna: Bosellia mimelica; Auf Peys-
sonnelia squamaria und krustenförmigen Kalkalgen (z.B. Pseudlithophyllum sp.): Callochiton
laevis-Chiton corrallinus-Assoz.

Höhlenwände im phytallosen Bereich:

Epilithion:

Gastropoda: Muricidea blainvillei-Tritonalia edwardsi-Cantharus d'orbigny-Assoz. mit
Vermetus-Arten.

Bivalvia: Ostrea edulis-Arca lactea-Assoz.

Auf Drusen des Schwammes Petrosia ficiformis:

Gastropoda: Peltodoris atromaculata

Endolithion:

Bivalvia: Lithophaga lithophaga-Gastrochaena dubia-Assoz. mit Petricola lithophaga, Beguinea

calyculata.
с. Rollblöcke:
Epilithion:

Placophora: Chiton olivaceus - Acanthochiton (communis, fascicularis) - Lepidopleurus
cajetanus-Assoz.

Gastropoda: Haliotis lamellosa-Diodora-Emarginula-Assoz. mit Capulus hungaricus, u.
kleineren vagilen Arten (kleine Trochidae, Muricidae).

Bivalvia: Anomia ephippium-Chama (gryphoides, gryphina)-Assoz.

Endolithion: Wie im freien Felslitoral.
d. Phytalbewuchs (Strauchalgen der Gattung Cystoseira):

Placophora: Am krustigen Kalkalgenaufwuchs der Stämmchen (z.B. Fosliella sp.): Chiton
olivaceus-Acanthochiton-Assoz.

Gastropoda: Bittium reticulatum-Rissoa variabilis-Alvania cimex-Assoz. mit Cantharidus-,
Gibbula-Arten, Rissoidae, Columbella rustica, Conus ventricosus, Tritonalia aciculata,
Elysia viridis, Thuridilla splendida, und bei starkem Hydrozoenzwischenwuchs mit versch.
Aeolidiacea.

Bivalvia: Musculus marmoratus-Brachyodontes minimus-Assoz. mit vereinzelten Beguinea

calyculata.

e. Anschüttungsböden:

Geodia-, Ascidia-, Vidalia volubilis-Mischböden:

Placophora: Auf Schell und Kalkalgen (Lithothamnium): Chiton corallinus-Callochiton
laevis -Assoz.

Gastropoda: Cerithium vulgatum-Aporrhais pes pelecani-Assoz. mit Murex trunculus, Diodora
italica, Astraea rugosa, Vermetus-Arten, Calyptraea sinensis, Capulus hungaricus,
Archidoris tuberculata, Dendrodoris limbata, Bouvieria aurantiaca u.a. Arten.

Bivalvia: Schellmaterial: Leere Schalen von Pecten jacobaeus, Chlamys-, Lima-, Cardium-,
Veneriden-Arten, Pitaria chione, Venus verrucosa.

STARMUHLNER 241

Im Sediment: Cardium exiguum-Nucula nucleus- Assoz.
Auf den Büscheln von Vidalia volubilis:

Gastropoda: Alvania cimex-Cerithium vulgatum-Assoz. mit Cerithium rupestre, Murex

trunculus, Polycera quadrilineata, Glossodoris gracilis u. selteneren Arten.
Sekundáre Hartböden:

Placophora und Bivalvia: Auf Kalkalgen, Schell, sowie im Sediment die gleichen Arten wie auf
den Mischböden.

Gastropoda: Capulus hungaricus-Calyptraea sinensis-Assoz. mit Murex trunculus, Astraea
rugosa, Cerithium vulgatum, Trivia adriatica, Calliostoma-Arten, Archidoris tuberculata
u.a. Arten.

f. Reine Sedimentböden:
Sandböden:
Mikrofauna der Grobsande:
Placophora: Lepidopleurus cancellatus-L. intermedius-Assoz.
Gastropoda: Prosobranchia: Caecum glabrum
Opisthobranchia: Microhedyle (mit M. milaschewitchii, M. glandulifera)-Pseudovermis
(mit P. papillifera, P.schulzi)-Hedylopsis spiculifera-Philinoglossa helgolandica-Assoz.
mit Tergipes despectus, Embletonia pulchra.
Mikrofauna der mittelfeinen Sande:
Opisthobranchia: Microhedyle glandulifera- Microhedyle lactea-Assoz.
Makrofauna der Sandböden:

Gastropoda: Prosobranchia: Natica millepunctata- Nassa mutabilis-Assoz. mit Polynices-
Arten.

Opisthobranchia: Actaeon tornatilis-Bullaria striata-Assoz. mit Philine aperta und
mehreren selteneren Cephalaspidea.

Scaphopoda: Dentalium dentale-D. vulgare -Assoz.

Bivalvia: Tellina distorta-Divaricella divaricata-Assoz. mit Solen vagina, Pinna nobilis,
Chlamys-, Cardium-, Venus-, Mactra-Donax-, Angulus-, Tellina-Arten.

Seegráser (Posidonia, Zostera):

Gastropoda: Alvania cimex-Bittium reticulatum-Assoz. mit Gibbula varia, Cantharidus
striatus, Cerithium-Arten, versch. Rissoidae, Columbella rustica, Conus ventricosus,
Runcina coronata, Elysia viridis u.a. Arten.

Bivalvia: Arca lactea-Modiolus barbatus-Assoz.

Phytallose Schlamm- und Tonböden:

Gastropoden: Turritella (mit T. triplicata, T. communis)-Aporrhais pes pelecani-Assoz. mit
Natica millepunctata, Polynices-, Cythara-, Melanella-, Chrysallida-, Eulimella-, und
Turbonilla-Arten, Murex brandaris.

Scaphopoda: Dentalium dentale-D. panormitanum-Assoz.

Bivalvia: Solen vagina-Cardium paucicostatum-Aloidis gibba-Assoz. mit Nucula-, Leda-,
Tellina-Arten, Venus casina, Abra alba u.a. Arten.

LITERATURVER ZEICHNIS

BRUSINA, S., 1896, Faunistisches von der Adriaexkursion der Yacht “Margita.”
Compt. Rend. Seances 3. Congr. Int. d. Zool. Leyden.

CARUS, V., 1889/93, Prodromus Faunae Mediterranea. Stuttgart, 2: 61-459.

COEN, G., 1937, Nuovo saggio di una sylloge molluscorum Adriaticorum. К. Com.
Talassogr. Ital. Mem., 290.

GRAEFFE, E., 1903, Ubersicht uber die Fauna des Golfes von Triest, nebst Notizen
über Vorkommen, Lebensweise, Erscheinungs- und Laichzeiten der einzelnen
Arten. Arb. Zool. Inst. Wien-Triest, 14: 88-136.

KUHNELT, W., 1930, Bohrmuschelstudien I, Palaeobiologica, 3: 53-91.

KÜHNELT, W., 1933, Bohrmuschelstudien II, Palaeobiologica, 5: 371-407.

KÜHNELT, W., 1938, Beziehungen zwischen Kalkstoffwechsel und Atmung bei Mollusken
der Meeresktiste. Zool. Anz., 124: 182-190.

KUHNELT, W., 1947, Bohrmuschelstudien II, Palaeobiologica, 7: 428-447.

KUHNELT, W., 1950, Contributions à la connaissance de l’endofauna des sols marins
durs. Coll. Int. Centre Nat. Rech. Scient. Ecol. Paris. Ann. Biol., 27: 281-291.

LELOUP, E. & VOLZ, P., 1938, DieChitonender Adria. Thalassia, Rovigno, 2.

242 PROC. THIRD EUROP. MALAC. CONGR.

LORENZ, J., 1863, Physikalische Verhältnisse und Verteilung der Organismen im
Quarnerischen Golfe. Wien, 379 р.

ODHNER, N. H., 1914, Beiträge zur Kenntnis der marinen Molluskenfauna von Rovigno
in Istrien. Zool. Anz., 44: 156-170.

RIEDL, R., 1953, Quantitative ökologische Methoden mariner Turbellarienforschung.
Osterr. Zool. Ztschr., 4: 108-145.

RIEDL, R., 1954, Unterwasserforschung im Mittelmeer. Osterreichische Tyrrhenia-
Expedition 1952. Naturw. Rundschau, Heft 2: 65-71.

RIEDL, R., 1963, Fauna und Flora der Adria. Hamburg/Berlin, 640 p.

RIEDL, R., 1966, Biologie der Meereshöhlen. Hamburg/Berlin, 636 p.

SALVINI-PLAWEN, L., 1968, Neue Formen im marinen Mesopsammon: Kamptozoa
und Aculifera (nebst der für die Adria neuen Sandformen). Ann. Naturhist. Mus.
Wien, 72: 231-272.

STARMÜHLNER, F., 1955a, Zur Molluskenfauna des Felslitorals und submariner
Höhlen am Capo di Sorrento (1. Teil). Ergebnisse der Österreichischen Tyrr-
henia-Expedition 1952, Teil IV. Österr. Zool. Ztschr., 6: 147-249.

STARMÜHLNER, F., 1955b, Zur Molluskenfauna des Felslitorals und submariner
Höhlen am Capo di Sorrento (2. Teil). Ergebnisse der Österreichischen Tyrr-
henia-Expedition 1952, Teil IV. Österr. Zool. Ztschr., 6: 631-713.

STARMÜHLNER, F., 1968, Investigations about the Mollusc-fauna in submarine caves.
Symp. Moll. Cochin (India) Part I: 137-163.

STOSSICH, A., 1865, Enumerazione dei molluschi del Golfo di Trieste. Triest.

VATOVA, A., 1928, Compendio della flora e fauna del mare Adriatico presso Rovigno
con la distrubuzione geogr. delle specie bentoniche. R.Com. Talass. Ital. Mem.,
143.

WEINKAUFF, M. C., 1867/68, Konchylien des Mittelmeeres, ihre geographische und
geologische Verbreitung. Kassel, 2 Bde., 512 u. 301 p.

WIMMER, A., 1883, Fundorte und Tiefenvorkommen einiger adriatischer Conchylien.
Verh. d. k. k. Zool. - Bot. Ges., 32: 255-264.

ZIMMERMANN, H., 1907, Tierwelt am Strande der blauen Adria. Ztschr. Naturw.
Halle., 79.

MALACOLOGIA, 1969, 9(1): 243-248

PROC. THIRD EUROP. MALAC. CONGR.
THE FLUID DYNAMICS OF MOLLUSCAN LOCOMOTION
E. R. Trueman

Department of Zoology
The University, Hull, England*

ABSTRACT

The importance of hydraulic mechanisms in molluscan locomotion is discussed in
terms of examples from the three major Classes, namely Patella, Ensis and Sepia.
In both the gastropods and the bivalves a double fluid-muscle system of internal (blood)
and external (water) fluids is utilised while in jet propulsion the cephalopods use only
the external fluid. Experiments with Patella have shown that the blood in the haemo-
coelic spaces near the sole of the foot and water, together with mucus, beneath the
sole are both concerned with the progression of retrograde pedal locomotory waves.
The passage of the latter correspond to negative pressures or suction beneath the
foot. In Ensis high pressure pulses (120 cm of water) are generated equally and simul-
taneously in the pedal haemocoele and mantle cavity during burrowing by means of
adduction of the valves, the blood causing dilation of the foot and the water from the
mantle cavity a jet which facilitates movement into the sand. In the cephalopods high
pressure (200 cm in Sepia) is developed in the mantle cavity for the purpose of swim-
ming. The possibility of a corresponding pressure pulse within the body, as in bi-
valves, and a consequent surge of blood passing to the head is envisaged as being
incompatible with the high neural organization of this group. It is suggested that the
extensive coelom in cephalopods may in part diminish this effect.

INTRODUCTION

Until relatively recently little was known about the hydraulic mechanisms of mol-
luscs. Studies using manometers and the traditional techniques of functional anatomy
by Trueman (1954) on Mya and by Chapman and Newell (1956) on the latter and
Scrobicularia demonstrated the relationship between fluid pressures and siphonal
movements. More modern techniques of continuously recording pressure changes
and body movements by means of transducers coupled to multichannel pen recorders
(Hoggarth & Trueman, 1967) have further elucidated fluid-muscle systems in the
three major molluscan groups.

Many soft-bodied animals have developed a capacious fluid skeleton which acts as
a hydraulic organ. It is well known, e.g. Chapman, 1958, that a fluid-muscle system
must operate with a constant volume of relatively incompressible, non-viscous fluid
and generally has two sets of muscles, for example, longitudinal and circular muscles,
acting in mutual antagonism. The clam, Mya, is one of the best examples in the
Mollusca for with the siphonal and pedal apertures closed the mantle cavity is vir-
tually watertight and the water enclosed acts together with the blood in the haemocoele
as the fluid of an antagonistic muscle system. Through the agency of these fluids,
from which pressure pulses may be recorded (Trueman, 1966), adduction causes
siphonal extension and conversely siphonal retraction produces an increase in gape
of the valves.

This paper will be restricted to adiscussionof aspects of locomotion in Gastropoda,
Bivalvia and Cephalopoda, one example being taken from each group. Previous work
has conveniently been summarised in all Classes by Morton (1964), by Gray (1968) in
respect of gastropods and by Trueman (1968b) concerning the burrowing activity of
bivalves.

*Present address: Department of Zoology, The University, Manchester, England.

(243)

244 PROC. THIRD EUROP. MALAC. CONGR.

O EME ESTE &

Be —
movement locomotory wave

FIG. 1. Diagram of a parasagittal section of the foot of Patella indicating the factors involved in the
progression of a retrograde locomotory wave (locomotory wave, arrow) and the forward movement of the
foot (movement, arrow). Haemocoele spaces (HS) are distorted and a negative pressure is exerted beneath
the foot by the contraction (C) of the dorso-ventral muscles (DV). This suction draws the epithelial sole
of the foot down when these muscles relax (R). The stippled dorsal region represents a thick layer of
muscle fibres, many of which lie transversely across the foot, immediately above the haemocoele spaces.

THE DYNAMICS OF LOCOMOTION
(a) Patella vulgata L.

Patella is adapted for life on a hard substratum having a foot which serves both for
locomotion and adhesion. In this genus separate locomotory waves pass down each
lateral half of the sole of the foot from the anterior margin. Such locomotory waves
are described as being ditaxic and retrograde.

The anatomical features of the foot concerned with locomotion are the superficial
epithelium, the haemocoelic spaces and the musculature. The latter principally con-
sists of dorso-ventral or shell muscles, passing from the sole of the foot to the
shell and the transverse muscles (Fig. 1). According to Jones (1968) there is no
longitudinal muscle near the sole of the foot although some fibres lie in the dorsal
pedal region, running through the transverse fibres. Blood occupies numerous spheri-
cal cavities (of about 10 y in diameter) of the diffuse pedal haemocoele which is situ-
ated ventrally in close proximity to the epithelium of the sole (Fig. 1). The passage
of each locomotory wave involves the contraction (C) of the dorso-ventral muscles so
as to lift the sole off the substrate. The epithelium is stretched, partially by the ten-
sion of these muscles, as is indicated by the increased interval between the dorso-
ventral muscle fibres in Fig. 1. The sole shortens to its original length as it is
lowered at the end of the step (R). This process results in forward movement as the
raised region of the sole passes across the foot as a retrograde locomotory wave.
Analysis of cine film in which the sole of the foot was marked by shallow transverse
incisions has allowed these movements to be demonstrated (Jones, 1968). This
lengthening of the part of the foot not attached to the ground is exactly parallelled by
the mechanism employed by the earthworm in retrograde locomotion (Gray, 1968), for
in worms the segments form anchorages or points d’appui at their shortest length and
are moved forwards at segmental elongation.

It was not possible to record pressures from the pedal haemocoele, because of the
small size of the blood spaces, but it is reasonable to assume that as the foot is
raised each part is somewhat compressed against the musculature above, so becoming
deformed (Fig. 1). Increase in the lateral dimensions of the foot is prevented by the
transverse musculature and the deformation of the haemocoele results in elongation

TRUEMAN 245

of the epithelial surface. A colleague, Dr. H. D. Jones, has been able to show negative
pressures of as much as 15 cm of water beneath each pedal wave caused by the con-
traction of the dorso-ventral muscles raising the epithelium so as to produce a
suction-like effect on the water and mucus beneath the foot. These muscles contract
at the leading edge of the pedal wave (Fig. 1, C) and, by means of the negative pressure
produced, antagonise the muscles at the lagging edge so that as these relax (В), пе
sole is drawn down into the substrate. The progression of the pedal wave in Patella
is thus brought about by the antagonism of muscles using both internal and external
hydraulic systems and the presence of longitudinal muscle fibres adjacent to the sole
is not required for locomotion except possibly at the trailing edge of the foot.

(b) Ensis arcuatus (Jeffreys)

The locomotory activity of burrowing bivalves follows a common pattern throughout
the group (Trueman, 1968b) and, although much modifiedin form, the rapidly burrowing
Ensis is a good example. The burrowing process consists of cyclically repeated move-
ments involving two principal stages: a, probing movements of the foot with the shell
held in position by the valves pressing against the sand (penetration or shell anchor);
and b, adduction of the valves followed immediately by pedal retraction, the foot being
dilated and held in the sand by the terminal or pedal anchor (Trueman, 1967; 1968a).
The fluid-muscle system is a double system consisting of two separate fluid filled
chambers, the mantle cavity and the haemocoele. During pedal extension and probing,
however, only the latter participates, the shape of the foot being changed by antagonism
between the retractor muscles and the transverse and protractor muscles. The blood
is the fluid of this system in which relatively low pressures, rising to a maximum of
10 cm of water in Ensis, are involved. Keber’s valve prevents the outflow of blood
and ensures that the foot operates at a nearly constant volume.

Adduction of the valves affects both internal and external fluids simultaneously and
equally, pressure pulses of up to 120 cmof water and 0.5 sec. duration being recorded
(Fig. 2a). In the haemocoele this pressure causes pedal dilation which ensures a
secure anchorage of the foot so that at pedal retraction the closed shell is drawn
down. The pressure in the mantle cavity produces powerful jets of water which
assist movement of the shell by loosening the adjacent sand. The hinged shell thus
acts as the basis of a hydraulic system by means of which the strength of adduction
may be used in digging.

During adduction the valves of Ensis pass through 20°, a relatively wide angle com-
pared with other burrowing bivalves, e.g. Mactra corallina, 8°, and represents a
reduction in the volume enclosed between the valves of about 20%. Of this 1/3 rd may
be accounted for by the passage of blood distally so as to dilate the foot, and 2/3 rds
as water ejected from the mantle cavity. In consequence of extensive mantle fusion
(Owen, 1959) and closure of the siphons the water is restricted into powerful jets
emerging through the pedal and fourth pallial apertures.

It has long been recognised that contraction of the mantle muscles of a squid or
cuttlefish produces a high pressure in the mantle cavity, a jet of water from the funnel
and movement of the animal in the opposite direction (Morton, 1964). Recordings
from the mantle cavity of Sepia (200-250 g. wet weight) showed a regular fluctuation
of pressure associated with respiration of about 44/min. with an amplitude of less
than 1 cm of water (Fig. 2c). This rhythm is broken by high pressure pulses produced
during jet Swimming. Visual observations made during the respiratory rhythm indi-
cated that the funnel was closed by a valvular flap as the pressure rose and that this
opened as the pressure fell allowing water to flow out. At the same time the inhalent

246 PROC. THIRD EUROP. MALAC. CONGR.

ARA A \ с

FIG. 2. Pressure recordings (cm of water) obtained from a, the pedal haemocoele of Ensis arcuatus
during burrowing; b &с, the mantle cavity of Sepia officinalis. a, pressure pulse generated by adduction
of the valves; b, pulse produced by mantle contraction during jet swimming; c, respiratory pressure fluc-
tuations followed by two swimming pulses of increasing amplitude and decreasing pulse width which inter-
rupt the respiratory rhythm. Oscillations occurring after the pressure pulses in b € саге due to the effect
of sudden reduction of pressure on the recording instrument.

channel is effectively blocked by the outer collar of the funnel locking into the car-
tilaginous sockets of the mantle. This mechanism ensures that water passes out
through the funnel and is particularly effective at the higher pressures produced dur-
ing Swimming. Recordings of the pressure generated in the mantle cavity of Sepia
during jetting showed pulses of up to 200 cm of water with a duration of 150 m sec.
at 3/4 amplitude (Fig. 2b). Such a maximal pressure pulse has a steep leading edge
and is brought about by a giant fibre response. Pulses of smaller amplitude show a
slower rise in pressure and longer duration (Fig. 2c), possibly due to the contrac-
tion of the mantle under the control of small diameter nerve fibres as Young (1938)
suggested in respect of contractions of the mantle of Loligo.

Data derived from recordings has allowed some assessment of the motor per-
formance of Sepia, Loligo, Eledone and Octopus and a discussion of the dynamics of
their propulsion (Trueman & Packard, 1968). The momentum (mass x velocity) of an
animal during jet propulsion is shown to be dependent on the volume and velocity of
the jet (Packard, 1966). Thus maximum swimming velocities depend on the expulsion
of as large a volume of water as possible from the mantle cavity. High velocity is
attained by the restriction of the exhalent current to a narrow funnel and by pulses
of high pressure but of short duration. Jetting cannot be a continuous process in the
cephalopods because of the need to refill the mantle cavity. This occurs between
pulses by the expansion of the mantle brought about by contraction of the radial
muscles (Wilson, 1960).

TRUEMAN 247
DISCUSSION

Hydraulic systems have been developed in the three principal groups of molluscs
for locomotory purposes. Extension of the foot in gastropods and bivalves is brought
about by relatively low internal pressures and apart from jet propulsion in the
cephalopods high pressures only occur in the body cavities of animals that burrow.
Similarly shaped pressure pulses with rapid rise time are produced in the bodies of
both bivalves and cephalopods but greater amplitude and shorter duration is charac-
teristic of the latter group.

The extent of the haemocoele in the foot is at its maximum in those molluscs that
burrow in which it functions as a hydraulic organ for the transference of the force of
muscular contraction from one part of the body to another. Thus the pedal haemocoele
of bivalves shows a larger cavity in Ensis, a genus notable for powerful digging move-
ments, than in more sedentary bivalves, e.g. Anodonta. Similarly the foot of the
burrowing gastropod Natica is greatly expanded by fluid-filled cavities in comparison
to that of Patella (Trueman, 1968c).

In all the molluscs discussed here the external fluid is exploited as an integral
part of the hydraulic mechanism of locomotion in addition to the body fluid in the
haemocoele. Both the Cephalopoda and the Bivalvia utilise the water contained within
the mantle cavity for locomotory purposes the pressure being generated by the pallial
muscles or, in the latter, their derivative, the adductor muscles (Yonge, 1957), the
jet produced in the Pectinidae by the flapping of the valves being used in swimming.
In both Classes advantage is to be gained by increased mantle capacity, for example,
by the relatively wide gape of the valves in Ensis and Chlamys, and by the restric-
tion in the size of the mantle openings so as to produce a more intense jet, as in the
funnel of Sepia.

In burrowing bivalves the flow of blood into the foot at adduction serves a loco-
motory function; but in the cephalopods the production of a jet must cause a surge of
blood into the large haemocoelic channels in the head, possibly affecting the focussing
of the eyes (Boycott & Young, 1956), which is scarcely compatible with the high neural
organisation of this group. Normal respiratory pressures in Sepia can have little
effect on blood flow but Johansen & Martin (1962) demonstrated that in the large
Octopus dofleini such pressures affect the circulatory system. The principal dis-
advantage of jet propulsion would thus appear to be the flow of blood to the head caused
by the pressure pulses. The extensive development of the coelom adjacent to the
mantle cavity may well function to restrict the surge of blood to the vena cava,
effectively buffering the arterial circulation from the effect of high pressure.

ACKNOWLEDGMENTS

The author is grateful to the University of Hull for a grant towards the cost of
attendance of the Malacological Congress and to his colleague, Dr. H. D. Jones, for
the use of material presented in a thesis and valuable discussion.

REFERENCES

BOYCOTT, В. В. € YOUNG, J. Z., 1956, The subpedunculate body and nerve and other
organs associated with the optic tract of cephalopods. т: Bertil Hanstróm:
zoological papers in honour of his sixty-fifth birthday, p. 76-105. Wingstrand,
K. G. (Ed.). Lund, Zoological Inst.

CHAPMAN, G., 1958, The hydrostatic skeleton in the invertebrates. Biol. Rev.,
33: 338-371.

248 PROC. THIRD EUROP. MALAC. CONGR.

CHAPMAN, G. & NEWELL, G. E., 1956, The role of the body fluid in relation to
movement in soft bodied invertebrates. II. The extension of siphons of Mya
arenaria L. and Scrobicularia plana (da Costa). Proc. roy. Soc. В, 145: 564-580.

GRAY, J., 1968, Animal locomotion. London, Weidenfeld & Nicolson.

HOGGARTH, К. В. € ТВОЕМАМ, Е. R., 1967, Techniques for recording the activity
of aquatic invertebrates. Nature, Lond., 213: 1050-1051.

JOHANSEN, K, & MARTIN, A. W., 1962, Circulation in the cephalopod, Octopus
dofleint. Comp. Biochem. Physiol., 5: 161-176.

JONES, H. D., 1968, Aspects of the physiology of Patella vulgata L. Ph.D. thesis,
University of Hull.

MORTON, J. E., 1964, Locomotion. Jn: Physiology of the Mollusca, Vol. I, p. 383-
423. Wilbur, K. M. & Yonge, C. M. (Eds.). New York, Academic Press.

OWEN, G., 1959, Observations on the Solenacea with reasons for excluding the family
Glaucomyidae. Phil. Trans. B, 242: 59-97.

PACKARD, A., 1966, Operational convergence between cephalopods and fish: an
exercise in functional anatomy. Archo. 2001. Ital., 51: 523-542.

TRUEMAN, E. R., 1954, The mechanism of the opening of the valves of burrowing
lamellibranch, Mya arenaria. J. exp. Biol. 31: 291-305.

TRUEMAN, Е. R., 1966, Fluid dynamics of the bivalve molluscs Mya and Margariti-
fera. J. exp. Biol., 45: 369-382.

TRUEMAN, Е. R., 1967, The dynamics of burrowing in Ensis (Bivalvia). Proc. roy.
Soc. B, 166: 459-476.

TRUEMAN, E. R., 1968a, Burrowing habit and the early evolution of body cavities.
Nature, Lond., 218: 96-98.

TRUEMAN, E. R., 1968b, The burrowing activities of bivalves. Symp. Zool. Soc.
Lond., 22: 167-186.

TRUEMAN, E. R., 1968c, The mechanism of burrowing of some naticid gastropods
in comparison with that of other molluscs. J. exp. Biol., 48: 663-678.

TRUEMAN, E. R. & PACKARD, A., 1968, Motor performances of some cephalopods.
J. exp. Biol., 49: 495-507.

WILSON, D. M., 1960, Nervous control of movement in cephalopods. J. exp. Biol.,
37: 57-72.

YONGE, С. M., 1957, Mantle fusion in the Lamellibranchia. Publ. Staz. 2001. Napoli,
29: 151-171.

YOUNG, J. Z., 1938, The functioning of the giant nerve fibres of the squid. J. exp.
Biol., 15: 170-185.

MALACOLOGIA, 1969, 9(1): 249-250
PROC. THIRD EUROP. MALAC. CONGR.

ZUR WURM-GLAZIALEN UBERDAUERUNG EUROPAISCHER
LANDGASTROPODEN IN EISRANDNAHE

Herbert Ant
Wielandstrasse 17, 47 Hamm, Germany
ZUSAMMENFASSUNG

Im letzten Interglazial (Eem, Riss/Würm) war die mitteleuropäische Landgastropodenfauna optimal
entwickelt. Die Lebensbedingungen waren äusserst günstig und vielseitig. Als gegen Ende der Eem-
Warmzeit die Temperaturen zurtickgingen (75000 vor heute), setzte auch eine langsame Abnahme der
Zahl der Land- und Stisswassermollusken-Arten ein. Im Würm-Glazial erreichte die Verarmung der
Molluskenfauna ihren Höhepunkt. Es ist verständlich, dass die Verarmung in Eisrandnáhe am grössten
war. Die Ausdehnung der Gletschermassen war im Wurm - im Vergleich zu anderen Glazialen - relativ
gering. Während des Maximums des Würms (20000 bis 18000 vor heute) betrug die Absenkung der
Jahresmitteltemperaturen: Südengland -12°, Pariser Becken -13°, Zentral-Ungarn -13°, Nordukraine -9°,
Mittellauf der Wolga -8°, West-Sibirien -3°. Die Absenkung der Juli-Temperaturen betrug: Südfrankreich
-10°, Wiener Pforte -9°, NO-Mitteleuropa -7° bis -8°, Südural und Nordjakutien -5°. Für Landgastro-
poden ist neben der Temperatur der Wasserhaushalt von ausschlaggebender Bedeutung. Im Würmglazial
war es nicht nur kälter, sondern auch trockener. Die Niederschläge sanken durchschnittlich um 40-60%.
Ein weiterer wichtiger Faktor für die Existenz von Landgastropoden ist die Vegetation. Der Wald fehlte
in Mitteleuropa in Eisrandnähe völlig. An seine Stelle war die Lössteppe getreten. In der nächsten Um-
gebung der Alpen und in Nordeurasien herrschten Artemisia-Steppen, die südliche Ukraine und der Süden
West-Sibiriens wurden durch Chenopodiaceae gekennzeichnet. In Mitteleuropa fanden sich niedrigwüchsige
Pflanzengesellschaften mit Potentilla, Plantago, Cruciferen, Compositen, Papilionaceen und Gramineen.
Im Osten Europas sind die Böden damals sicherlich stark salzhaltig gewesen. Ein relativ stabiles Klima
wird für Mittel- und Ost-Sibirien angegeben. Dort sind zum Teil Waldsteppen nachgewiesen. Während
anfangs in Mitteleuropa Grassteppen herrschten, wurden sie später durch Kräutersteppen ersetzt. Die
Böden waren in Dauerfrostgebieten Brodelböden, die immer wieder frisches Material aus der Tiefe nach
oben brachten. Die Auslaugung bzw. Auskalkung war also gering. Begünstigt wurde dieser Umstand
durch die geringen Niederschläge. In Eisrandnähe Nordwest-Deutschlands sind folgende Landgastropoden
nachgewiesen: Succinea oblonga, Trichia hispida, Pupilla muscorum, Columella columella, Vertigo par-
cedentata, Cochlicopa lubrica, Truncatellina cylindrica, Vertigo antivertigo, Vertigo pygmaea, Vertigo
substriata, Vallonia pulchella, Vallonia costata, Vallonia tenuilabris, Succinea putris, Succinea antiqua,
Punctum pygmaeum, Discus rotundatus, Arion sp., Eucobresia diaphana, Nesovitrea hammonis, Nesovitrea
petronella, Limax sp., Deroceras sp., Euconulus fulvus, Clausilia pumila, Helicigona lapicida, Avianta
arbustorum. Das sind 24% der rezenten Fauna im gleichen Gebiet. Insgesamt gesehen waren also die
Lebensbedingungen für Landgastropoden während des Würmglazials zur Zeit seines Maximums in Eisrand-
nähe Nordwestdeutschlands relativ günstig, so dass Arten des holopaläarktischen und europäischen Ver-
breitungstyps mit grosser ökologischer Valenz die Eiszeit am Ort zu überdauern vermochten. In Süd-
deutschland liegen besondere Verhältnisse vor, die in der Bodenmorphologie begründet sind. Dort gab es
viele ökologische Nischen, deren Lokalklima ein besseres Ausharren ermöglichte. Ausserdem war die
Wirkung der alpinen Eiskappe nicht so stark wie die der nordischen.

Neben diesen mitteleuropäischen Eisrand-Refugien gab es in Europa noch andere Gebiete, an denen
Landgastropoden unter besonderen Bedingungen die Würm-Eiszeit überdauern konnten. In Nordwest-
Skandinavien blieben einige Gebiete an der Küste infolge des Golfstromes eisfrei. Hier tiberdauerten z.B.
etwa 29% der Carabiden die Eiszeit. Durch zahlreiche endemische Pflanzenarten (z.B. Papaver relictum,
Taraxacum dourense) ist diese Annahme ziemlich gesichert, obwohl sie von einigen Geologen abgelehnt
wird. Auch im Inlandeis gab es eisfreieStellen (Nunatakr). Ähnliche Verhältnisse finden wir in den Alpen.
Hier ist eine reiche Kleinfauna nachgewiesen, die inneralpin die Eiszeit Überdauert hat. Unter den Mollus-
ken gehören verschiedene Vitriniden und Cylindrus obtusus hierher. Dass viele Arten in unmittelbarer
Nähe des Eises zu leben vermögen, zeigen neuere Untersuchungen in Island. In wenigen hundert Metern
vom Eisrand entfernt leben dort z.B.: Arionaler, A. subfuscus, A. intermedius, Cochlicopa lubrica,
Columella aspera, Euconulus fulvus, Nesovitrea hammonis, Vitrina pellucida u.a.; Arten mit etwas höheren
Ansprüchen an die Temperatur lebten in Süd-England: Acme inchoata, Truncatellina britannica, Geomal-
acus maculosus, Zonitoides excavatus und Ashfordia granulata.

Die Lebensbedingungen in Eisrandnähe waren also keineswegs so ungünstig, wie es vielfach angenommen
wird. Keineswegs ist aber die Annahme berechtigt, dass es im Sinne einer Tabula-rasa-Theorie zur völ-
ligen Auslöschung gekommen ist. Von den rezenten Arten lebten in Mitteleuropa 25-30% auch während des
Maximums des Würmglazials an den gleichen Stellen wie heute.

(249)

250 PROC. THIRD EUROP. MALAC. CONGR.

LITERATUR

ANT, H., 1963, Die würmperiglaziale Molluskenfauna des Lippe- und Ahse-Tales bei Hamm. Neues Jahrb.
Geol. Palüont. Mon.-H., 1963, 77-86.

АМТ, H., 1963, Faunistische, ökologische und tiergeographische Untersuchungen zurVerbreitung der Land-
schnecken in Nordwestdeutschland. Abh. Landesmus. Naturk. Münster, 25: 1-125.

АМТ, H., 1965, Der boreo-alpine Verbreitungstypus bei europäischen Landgastropoden. Zool. Anz. Suppl.,
28: 326-335.

ANT, H., 1966, Die Bedeutung der Eiszeiten für die rezente Verbreitung der europäischen Landgastro-
poden. Malacologia, 5: 61-62.

ANT, H., 1967, Die Geschichte der westfälischen Landschneckenfauna. Veröff. Naturwiss. Vereinig.
Ltidenscheid, 7: 35-47.

FRENZEL, B., 1960, Die Vegetations- und Landschaftszonen Nord-Eurasiens während der letzten Eiszeit
und während der postglazialen Wärmezeit. II. Akad. Wiss. Lit. Mainz, Abh. Math.-naturwiss. Kl.,
1960, 287-453.

FRENZEL, B., 1967, Die Klimaschwankungen des Eiszeitalters. Braunschweig (Vieweg).

HOLDHAUS, K., 1954, Die Spuren der Eiszeit in der Tierwelt Europas. Abh. Zool. Bot. Ges. Wien, 18:
1-493.

LINDROTH, C. H., 1949, Die fennoskandischen Carabidae. III. Allgemeiner Teil. K. Vet. Vitterh. Samh.
Handl. Е. 6. Ser. В, 4: 1-911

LINDROTH, С. H., 1965, Skaftafell, Iceland, a living glacial refugium. Ozkos, Suppl., 6: 1-142.

LOVE, A. &D. (edit.), 1963, North Atlantic Biota and their History. Oxford (Pergamon).

MANI, M. S., 1967, Ecology and Biogeography of high altitude Insects. Den Haag (Junk).

STEUSLOFF, U., 1938, Neue Beitráge zur Molluskenfauna und Okologie periglazialer und altalluvialer
Ablagerungen im Emscher-Lippe-Raum. Arch. Moll., 70: 161-193.

STEUSLOFF, U., 1943, Der Lebensraum der Lösschnecken. Z. Geschiebeforsch. Flachlandsgeol., 19:
18-26.

STEUSLOFF, U., 1951, Neue Beobachtungen und Erkenntnisse über Flora, Fauna und Klimageschichte
des Würmperiglazials in der Niederterrasse der Emscher und der Lippe. Abh. Landesmus. Naturk.
Münster, 14: 1-45.

THIEL, E., 1951, Die Eiszeit in Sibirien. Erdkunde, 5: 16-35.

THIENEMANN, A., 1950, Verbreitungsgeschichte der Süsswassertierwelt Europas. Stuttgart (Schweizer-
bart).

WOLDSTEDT, P., 1955, Norddeutschland und angrenzende Gebiete im Eiszeitalter. Stuttgart (Koehler).

WOLDSTEDT, P., 1954, 1958, Das Eiszeitalter. I. II. Stuttgart (Enke).

MALACOLOGIA, 1969, 9(1): 251-252

PROC. THIRD EUROP. MALAC. CONGR.
THE ELEVATION EFFECT IN CYLINDRUS OBTUSUS (DRAPARNAUD 1805)
W. Backhuys

Natuurhistorisch Museum
Rotterdam, The Netherlands

ABSTRACT

The elevation effect may be defined as the phenomenon, that certain mountain plants or animals occur
only on mountains or mountain ranges exceeding a certain minimum altitude; it also includes the fact that,
on these mountains, the organisms in question may descend to comparatively low altitudes. These or-
ganisms are absent on mountains or mountain ranges which are lower than the required minimum altitude.
The elevation effect may be expressed in figures as the difference between the minimum required altitude
of the mountains and that of the lowest known locality. If, for example, a plant occurs from 1500 m onwards,
but only on mountains exceeding 2200 m, the elevation effect amounts to 2200-1500=700 m. So far this effect
has been demonstrated to occur in mountain plants on Java, New Zealand and in Switzerland (van Steenis,
1933, 1934; Backhuys, 1968).

The explanation is that each mountain plant occupies a zone of permanent establishment, on both sides
bordered by a zone of temporary localities, the critical altitude being the lower contour of the zone of
permanent establishment. In other words, mountain plants can only descend to their lowest localities on
mountains of which the summits are within or above the zone of permanent establishment, ensuring a con-
stant source for descending diaspores. The lowest localities are entirely dependent on a continuous supply
of diaspores from the permanent, higher situated populations.

The elevation effect is influenced by various ecological factors, the most important of which are:
temperature, soil, physiognomy of the vegetation, autecology, dispersal biology and man. It appears
that the lowest localities always occur on sites which in one way or another differ from the surrounding
habitat e.g., by lower temperature, more open vegetation, etc. Such “enclaves” show most of the characters
of higher situated zones; these are for example borders of streams, glaciers, deep ravines, waterfalls, etc.

Since the animal world is often closely connected with the vegetation, the question arose whether this
phenomenon could also be found in montane animals. As an example we took Cylindrus obtusus (Draparnaud,
1805), a land snail endemic to Austria. The distribution of this species is well-known and all localities
have been enumerated and numbered by Adensamer (1937) and by Klemm (1961).

It appears that all localities of Cylindrus obtusus are situated on mountains or mountain ranges exceeding
1600 m. The lowest known locality of Cylindrus obtusus, however, is at an altitude of 1100 m. Thus
the elevation effect of Cylindrus obtusus amounts to 500 m.

In connection with what we have found about the lowest known records of mountain plants, it is not sur-
prising to find that the lowest localities of Cylindrus obtusus are situated in “enclaves” in the vegetation,
showing most of the characters of higher situated zones.

ZUSAMMENFASSUNG

Unter dem Elevations-Effekt versteht man die Erscheinung, dass z.B. Bergpflanzen nur auf Bergen oder
Bergkomplexen vorkommen, die eine bestimmte minimale Gipfelhöhe besitzen, und dass die betreffenden
Pflanzen auf diesen Bergen und Bergkomplexen tief hinabsteigen können. Auf Bergen und Bergkomplexen,
die niedriger als diese minimale Gipfelhöhe aber höher als der niedrigste Fundort sind, kommen diese
Pflanzen nicht vor. Der Elevations-Effekt kann zahlenmässig ausgedrückt werden als der Unterschied
zwischen dieser minimalen Gipfelhöhe und dem niedrigsten Fundort. Wenn eine Pflanze z.B. vorkommt ab
1500 m, aber nur auf Bergen, die höher als 2200 m sind, beträgt der Elevations-Effekt also 2200 - 1500 =
700 m.

Bisher ist dieser Effekt bei Bergpflanzen auf Java, auf Neu-Seeland und in der Schweiz gefunden worden
(v. Steenis, 1933, 1934, Backhuys, 1968). Die Erklärung dieses Effekts ist, dass wir im Verbreitungs-
gebiet einer Bergpflanze eine Zone der Dauer-Ansiedlung, die nach oben wie nach unten durch je eine Zone
von zeitweilig möglichen Standorten begrenzt wird, unterscheiden können; die minimale Gipfelhöhe stimmt
mit der untersten Grenze der Zone der Dauer-Ansiedlung überein. Für die Instandhaltung der Populationen
auf niedrigen Standorten ist eine stetige Diasporenzufuhr von oben herab notwendig. Auf hohen Bergen
kann die Art bis auf grosse Tiefe vorkommen, weil die Diasporenzufuhr aus der höheren Zone ununter-
brochen stattfindet.

Der Elevations-Effekt wird von verschiedenen ökologischen Faktoren beeinflusst, wovon die wichtigsten
sind: die Temperatur, der Boden, die Physiognomie der Vegetation, die Autökologie, die Verbreitungs-

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252 PROC. THIRD EUROP. MALAC. CONGR.

biologie und der Mensch. Es zeigt sich, dass die niedrigsten Fundorten sich auf Stellen befinden, die auf
irgendeine Weise von der Umgebung abweichen z.B. durcheine niedrigere Temperatur, offenere Vegetation
usw. Solche Enklaven, z.B. Fluss-Alluvionen, Gletscher, tiefe Schluchten, Wasserfálle usw., zeigen die
Eigenschaften hóher gelegener Zonen.

Da die Tierwelt oft eng mit der Vegetation zusammenhängt, haben wir uns gefragt, ob dieser Effekt auch
bei Tieren gefunden werden könnte. Als Beispiel haben wir Cylindrus obtusus (Draparnaud, 1805) gewählt,
eine in Österreich endemische Landschnecke. Die Verbreitung dieser Art ist sehr gut bekannt und alle
Fundorte sind von Adensamer (1937) und von Klemm (1961) beschrieben und numeriert worden. Es zeigt
sich, dass alle Fundorte von Cylindrus obtusus auf Bergen, die höher als 1600 m sind, liegen. Der
niedrigste Fundort von Cylindrus obtusus liegt aber auf einer Höhe von 1100 m. Der Elevations-Effekt
von Cylindrus obtusus beträgt also etwa 500 m.

In Zusammenhang mit dem, was wir in bezug auf die niedrigsten Fundorte von Pflanzen gefunden haben,
ist es nicht verwunderlich, dass die niedrigen Fundorte von Cylindrus obtusus in Enklaven in der Vegeta-
tion liegen, die die Eigenschaften höher gelegener Zonen zeigen.

REFERENCES

ADENSAMER, W., 1937, Cylindrus obtusus (Draparnaud, 1805), seine relikthafte Verbreitung und geringe
Variabilität, sowie zoogeographisch-phylogenetische Betrachtungen über alpine Mollusken überhaupt.
Arch. Moll., 69(3): 66-116.

BACKHUYS, W., 1968, Der Elevations-Effekt bei einigen Alpenpflanzen der Schweiz. Blumea, 16(2):
273-320.

KLEMM, W., 1961, Fortführung der Numerierung der Fundorte von Cylindrus obtusus (Draparnaud).
Arch. Moll., 90(1/3): 43-49.

STEENIS, C. G. G. J. van, 1933, Report of a botanical trip to the Ranau Region, South Sumatra. Bull.
Jard. Bot. Btzg., 3(13): 1-56 (esp. chapt. 7: Occurrence of mountain plants at low altitudes, p 37-56).

STEENIS, С. С. С. J. van, 1934, On the origin of the Malaysian mountain flora. Part 2. Altitudinal zones,
general considerations, and renewed statement of the problem. Bull. Jard. Bot. Btzg., 3(13): 289-518

(esp. 292-302).

MALACOLOGIA, 1969, 9(1): 253
PROC. THIRD EUROP. MALAC. CONGR.
REPRODUCTION IN APLYSIA (GASTROPODA, OPISTHOBRANCHIA)
A. Bebbington and T. E. Thompson

Department of Zoology, University of Bristol, England
and Institut de Biologie marine d’Arcachon, France

ABSTRACT

Aplysia, like other Euthyneura, is hermaphrodite. The present work has been concerned with 3 northeast
Atlantic species: A. depilans (Gmelin 1791), А. fasciata Poiret 1789 and A. punctata Cuvier 1803. A
number of authors have described the anatomy of the aplysiid reproductive system and these are listed by
Thompson & Bebbington (1969). The hermaphrodite tracts of Aplysia show incomplete separation of the
efferent channels for the male and female gametes. The system functions so as to translocate oocytes (by
ciliary action) during oviposition, to expel autosperms (by ciliary and muscular action), and to receive
allosperms transferred during chain-copulation.

Study of the ultrastructure of the aplysiid spermatozoon shows that previous authors (Retzius 1906,
Tuzet 1940 and Franzén 1955) have misinterpreted the various components of this unique type of gamete.
The nucleus is shown to have a helical structure which extends to the anterior tip of the head; no acro-
some could be detected. The flagellum originates anteriorly close to the anterior tip of the gamete and
has a pair of mitochondrial strands helically disposed along its length.

The efferent passage of female gametes during oviposition and the build-up of the spawn-mass were fol-
lowed in serial sections of ovipositing specimens. Artificial fertilizations are reported for the first time
for an internally fertilizing gastropod.

Maturation and fertilization of the ova are complete a few hours after spawning and two polar bodies are
extruded. Two cells are formed, one of which (AB) is larger than the other (CD). The second division is
also unequal. During divisions the cells tend to meet over only a relatively small area but later become
closely associated and their shape modified. The spiral nature of cleavage is most obvious after the third
division. Cleavage continues in a series of alternate dexiotropic and laeotropic divisions to form a stereo-
blastula. The sterroblastula gastrulates by epiboly. The larval shell darkens 2-3 days after it is formed.
By the time the veliger is ready for hatching the egg string is fragile and easily broken.

After hatching the larvae swim upwards and may become trapped in the surface film of the water. During
Swimming the velar lobes are held uppermost, the shell down. Locomotion is effected by the beat of the
long velar cilia which impart a forward motion to the larva. Swimming activity is interrupted at intervals,
the larva partially retracting into the shell and sinking slowly. Veliger larvae have been maintained in the
laboratory for up to a fortnight after hatching.

Many problems about reproduction in Aplysia remain. The search for a food-plant or substance which
will induce progressive development and settlement of the larvae must go on. Without this information the
details of metamorphosis remain a mystery. The method by which the allosperms are activated in the
receptaculum seminis has not been shown. Nothing is known about the endocrine control of reproduction;
Vicente (1966) and Kupferman (1967) have claimed to have solved this problem, but their results have
proved impossible to verify. Finally, by what means do stray male and female gametes get into the gameto-
lytic gland and are the spermatozoa allosperms or autosperms or both?

REFERENCES

FRANZEN, A., 1955, Comparative morphological investigations into the spermiogenesis among Mollusca.
Zool. Bid., Uppsala, 30: 399-456, pls. 1 and 2.

KUPFERMANN, I., 1967, Stimulation of egg laying: possible neuroendocrine function of bag cells of ab-
dominal ganglion of Aplysia californica. Nature, Lond., 216: 814-815.

RETZIUS, G., 1906, Die Spermien der Gastropoden. Biol. Unters., 13: 1-36, taf. I-XII.

THOMPSON, T. E. & BEBBINGTON, A., 1969, Structure and function of the reproductive organs of three
species of Aplysia (Gastropoda, Opisthobranchia). Malacologia, 7(2/3): 347-380.

TUZET, O., 1940, La spermiogénése d’Aplysia depilans Linné. Arch. Zool. exp. gén., 81(notes et rev.):
130-138,

VICENTE, N., 1966, Sur les phénomènes neurosécrétoires chez les Gastéropodes Opisthobranches. С. В.
Acad. Sci., Paris, 263: 382-385.

(253)

MALACOLOGIA, 1969, 9(1): 254-255
PROC. THIRD EUROP. MALAC. CONGR.
SYSTEMATICS OF THE VESICOMYIDAE (MOLLUSCA;BIVALVIA)
Kenneth Jay Boss

Museum of Comparative Zoology, Harvard University
Cambridge, Massachusetts, U.S.A.

ABSTRACT

Benthic, shelled mollusks which live in the deepsea from the edge of the continental shelf to the abyssal
plain are usually small in size with delicate sculpturing and a thin, pearly shell substance enveloped ex-
ternally by a drably colored periostracum. The archibenthic zone between 200 and 1,000 meters may be
described as aphotic or dysphotic since little if any light penetrates beyond these depths. The substrate
may be a fine mud or silt and occasionally considerable organic material occurs in the water immediately
above the substrate since in certain archibenthic habitats, unusually large, filter feeding bivalves are found
which have been referred to the family Vesicomyidae.

This family was established by Dall & Simpson (1901) for a group of predominantly archibenthal, in-
faunal mollusks characterized by a peculiar, but heterodont, dental configuration, dehiscent periostracum
and often heavy, chalky shells. Numerous species have been described from material collected by the
major oceanographic expeditions, and certain of them have been listed and reviewed (Lamy, 1920; Odhner,
1960; Boss, 1968).

The affinities of the group have been questioned: representative species have been considered in the
Isocardiidae, Kelliellidae, Veneridae, Carditidae and Arcticidae. Anatomical material and new species
recently obtained from the Caribbean Sea near Panama offer new data which clarify the systematic position
of the group. Anatomically, both the vesicomyid genera Calyptogena and Callogonia are typified by a
large, laterally compressed and anteriorly pointed foot with a concomitant extensive ventral pedal gape.
Posteriorly there are small incurrent and excurrent siphonal openings associated with posterior thicken-
ings of the mantle muscles which function as siphonal retractors and may or may not leave a vague pallial
sinus impressed on the shell. Apparently homorhabdic and nonplicate, the gills consist of a large, ventrally
directed inner demibranch and a dorsal, smaller outer demibranch. Both have descending and reflected
lamellae. The thick and tumid gills are also large and extensive with the dorsal portion of the outer demi-
branch extending into the umbonal cavity. The labial palps are significantly reduced to extremely small
folds or lips which border the mouth. The combination of these anatomical traits with the conchological
ones involving the periostracum, ligament, dentition, shell substance, and configuration of the pallial line
serve to circumscribe the limits of the Vesicomyidae.

Nevertheless, various and diverse members of this group show conchological features in common with
the Kelliellidae and, possibly, the Veneridae. The Vesicomyidae are anatomically and conchologically
distinct from the Isocardiidae, Carditidae, Arcticidae and Astartidae. The morphology of Kelliella was
discussed by Clausen (1958) while the great anatomical diversity of the Veneridae was the subject of
Ansell's research (1961). Kelliella, at about 3 mm in maximum length, and the vesicomyids, Calyptogena
and Callogonia at over 100 mm, differ greatly in size but anatomically they are quite similar. Kelliella,
however, has a cylindrical foot, only a single posterior siphon and an anterior incurrent water flow, which
is probably a primitive feature inthe Heterodonta (Allen, 1958; 1968). The vesicomyids have both posterior
siphons developed but their pallial currents have not been studied.

With a discontinuous but cosmopolitan distribution, the species of the Vesicomyidae form into distinct
Artenkreise in which the most closely related or analogous species are geographically isolated from each
other. Five generic assemblages may be distinguished: 1) Vesicomya which may be further subdivided
into smaller shelled forms with 7 species andlarger shelled forms with 6 species; 2) Callogonia (+ Archi-
vesica) with 9 species; 3) Calyptogena with 7; 4) Ectenagena with 2; and 5) Kelliella-like forms with 9
species,

The smallest of the vesicomyids are all included in the fifth assemblage mentioned above. Among them
is the type-species of Vesicomya, Callocardia atlantica Smith 1885, which may prove to be a Kelliella, in
which case some nomenclatorial changes will have to be made. Nonetheless, the systematic relationships
of the Vesicomyidae seem to be with the venerid clams, for their dentition is virtually identical with that
of Venerupis, they have incurrent and excurrent siphons developed posteriorly and possess an extensive
anteroventral pedal gape. Further, if Vesicomya and Kelliella prove to be synonymous, and if Calyptogena,
Callogonia and Ectenagena confamilial, then it is quite possible that the smallest individuals in this group
are neotenous venerids, similar in that respect to the neotenous venerid Turtonia (Ocklemann, 1964).

(254)

K. J. BOSS 255

LITERATURE CITED

ALLEN, J. A., 1958, On the basic form and adaptations to habitat in the Lucinacea (Eulamellibranchia).
Phil. Trans. R. Soc. (B), 241: 421-484, 53 figs.

ALLEN, J. A., 1968, The functional morphology of Crassinella mactracea (Linsley) (Bivalvia; Astartacea).
Proc. malac. Soc. London, 38(1): 27-40.

ANSELL, A. D., 1961, The functional morphology of the British species of Veneracea (Eulamellibranchia).
J. mar. biol. Ass. U. K., 41: 489-515.

BOSS, К. J., 1968, New species of Vesicomyidae from the Gulf of Darien, Caribbean Sea (Bivalvia; Mollusca).
Bull. Mar. Sci., 18(3): 731-748, 28 figs.

CLAUSEN, C., 1958, On the anatomy and histology of the eulamellibranch Kelliella miliaris (Philippi) with
observations on the ciliary mechanisms in the mantle cavity. Nytt Mag. Zool., 6: 144-175.

DALL, W. H. & SIMPSON, C. T., 1901, The Mollusca of Puerto Rico. U.S. Fish. Comm. Bull., 20(1):
351-524, pls. 53-58.

LAMY, E., 1920, Révision des Cypricardiacea et de Isocardiacea vivantes. Jour. de Conch., 64: 259-307.

OCKELMANN, K. W., 1964, Turtonia minuta (Fabricius), a neotenous Veneracean bivalve. Ophelia. 1(1):
121-146.

ODHNER, H. H., 1960, Mollusca. Rept. Swed. Deep-sea Exped., 2(Zool. 22): 365-400, 2 pls., 12 text-figs.

MALACOLOGIA, 1969, 9(1): 256-258
PROC. THIRD EUROP. MALAC. CONGR.
NOTES ON THE DISTRIBUTION OF TERRESTRIAL MOLLUSCS IN SOUTHERN AFRICA
A. C. van Bruggen

Department of Systematic Zoology of the University
c/o Rijksmuseum van Natuurlijke Historie, Leiden, The Netherlands

ABSTRACT

Southern Africa, the subcontinent south of the Cunene and Zambezi Rivers, represents an immense
stretch of country with a varied geography and climate. Rainfall is of prime importance to the land mol-
luscs and in many cases appears to be the limiting factor (e.g., in the genus Xerocerastus); the greatest
number and diversity of species is found to the east of the main watershed formed by the Drakensberg
range.

Southern Africa is inhabited by about 6401 indigenous species of terrestrial molluscs, representing 73
genera and 27 families. This works out at approximately 49 species per 100.000 square miles; this high
figure is about equalled by the ex-Belgian Congo, but is much lower in Europe (> 40) and North America
(9). This may be caused by the diversity of habitat from tropical rain forest to desert, the location of
Southern Africa at subtropical and tropical latitudes, and the chequered geological history (‘Gondwanaland’,
etc.).

In the overall picture the dominant families are the Streptaxidae (>135 species), Endodontidae (>110
species), Subulinidae (about 80 species) and Urocyclidae (about 70 species). Achatinidae and Enidae are
also very well represented. These six families between them account for almost 75% of the known species
of the area. Of the above families the Streptaxidae and Subulinidae are circumtropical and the Enidae an
Old World family; the Achatinidae and Urocyclidae are African families (Achatinidae with one genus en-
demic to Madagascar). The Endodontidae belong to the Southern Relict Fauna (cf. Solem, 1959).

A marked endemism at various levels characterizes this assemblage of species: endemic families (one:
Aperidae), subfamilies (one: Oopeltinae, Arionidae), tribes (one) and genera (16: Chondrocyclus, Afriboy-
sidia, Afrodonta, Oopelta, Sheldonia, Xevocevastus, Coeliaxis, Metachatina, Trigonephrus, Tulbaghinia,
Dorcasia, Prestonella, Nata, Natalina, Арета, Sculptaria). Fauxulus and Trachycystis may be con-
sidered near-endemics or subendemics, i.e., genera of which the bulk of the subgenera and species are
endemic to Southern Africa. Of the endemic genera eight belong to families not otherwise represented in
Subsaharan Africa, viz., Arionidae, Acavidae, Amphibulimidae, Rhytididae and Corillidae. The endemic
genera belong to three groups of families, viz., families belonging to the Ethiopian Region (Urocyclidae
and Achatinidae), those belonging to the Southern Relict Fauna (Endodontidae, Acavidae, Rhytididae and
Aperidae) and those belonging to more widely distributed families (Cyclophoridae, Chondrinidae, Arionidae
and Subulinidae). The families Amphibulimidae and Corillidae, represented by the genera Prestonella and
Sculptaria respectively, are probably also Southern Relict elements.

Endem centres of great importance are South West Africa, where a specialized fauna with peculiar
Subulinidae, Achatinidae, Acavidae, Corillidae, etc., has developed, and the Southwest Cape Province with
endemic Endodontidae, Arionidae, Acavidae and Rhytididae. Minor centres are particularly found in the
interrupted parts of the Drakensberg range (N. Transvaal, E. Rhodesia); endemism here is on a specific
rather than generic level.

Twenty-one families (78% of the total) and 57 genera (also 78% of the total) testify to connections with
Central and East Africa, from which areas muchof the fauna must have been derived. However, only about
70 species (11% of the total), mainly belonging to four families, are known also to occur north of the
Zambezi.

The tropical element is strongly represented among the terrestrial molluscs of Southern Africa. It is
mainly confined to southeast Africa in a rapidly narrowing belt along the coast east of the main watershed.
In some groups the extension is two-pronged, penetration in a westward direction having been accompanied
by adaptation to the semi-desert conditions of the central and western parts of Southern Africa (e.g.,
Achatinidae). From north to south there is a rapid decrease in the number of taxa of tropical families as
witnessed by the number of genera in the Subulinidae:

south of the Zambezi River 11 roughly at ТО Lats:
south of the Limpopo River 9 roughly at 22° Lat. $.
south of the Tugela River 7 roughly at 29° Lat. S.
south of the Great Fish River 6 roughly at 33° 30’ Lat. S.
south of the Gouritz River 1 roughly at 34° 30’ Lat. S.

lay figures are approximate.

257

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os =

258 PROC. THIRD EUROP. MALAC. CONGR.

The distribution pattern of the temperate elements isthe reverse of the above. Southern Relict elements
such as the Endodontidae, Acavidae, Aperidae and Rhytididae show a marked decrease in number of species
north of the Great Fish River, which trend is continued north of the Limpopo and Zambezi Rivers. Fig. 1
shows the southern limits of some tropical and northern limits of some temperate families in the area
under discussion.

This illustrates the essential bipolarity in the distribution of the Southern African land molluscs: from
north to south the typically African character of the terrestrial molluscs gradually changes into that of a
Southern Relict Fauna. The tropical elements must have originated in Central and East Africa, while the
Southern Relict elements must have had their origin in the south. Darlington (1965) has summarized data
on the southern continents and has concluded that at one time these have been much closer than today, al-
though probably not forming a closed and continuous continent (‘Gondwanaland’). Absence of relevant fossils
on the Northern Hemisphere leads to the preliminary conclusion that the Southern Relict mollusc families
may indeed have originated on this “continent.”

Detailed distributions have been greatly influenced by the climate in the past and present, particularly
in and after the Pleistocene. Afewelements must have come from the north at a time when much of Africa
enjoyed a considerably cooler and wetter climate; these palaeogenic elements are found e.g., in the families
Arionidae (genus Oopelta) and Clausiliidae (Macroptychia africana).

The distribution of the land molluscs of Southern Africa has been more extensively dealt with in the
present author’s recent paper (Van Bruggen, 1969).

REFERENCES

BRUGGEN, A. C. van, 1969, Studies on the molluscs of Zululand with notes on the distribution of land
molluscs in Southern Africa. Zool. Verhand., Leiden, 103: 1-116.

DARLINGTON, P. J., 1965, Biogeography of the southern end of the world. Harvard University Press,
Cambridge, Mass.

SOLEM, A., 1959, Zoogeography of the land and freshwater Mollusca of the New Hebrides. Field. (Zool.),
43: 239-359.

MALACOLOGIA, 1969, 9(1): 259-260
PROC. THIRD EUROP. MALAC. CONGR.

THE SYSTEMATIC POSITION OF THE ATHORACOPHORIDAE
(GASTROPODA: EUTHYNEURA)!

J. B. Burch2 and C. M. Patterson

Museum of Zoology, University of Michigan, Ann Arbor, Michigan, U.S.A.
and Bernice P. Bishop Museum, Honolulu, Hawaii, U.S.A.

Burch (1968, J. malacol. Soc. Austr., 11: 62-67) has shown that tentacular structure and mode of tentacle
retraction in the Athoracophoridae are different from that described in other Stylommatophora, indicating
that these slugs may be quite distinct. However, we recently studied in detail the tentacle retraction of
Succineidae (Catinella, Omalonyx, Oxyloma, Quickia and Succinea), and the unexpected results of these
studies caused us to re-examine living animals ofas many different land snail groups as were immediately
available to us (Fig. 1). This led to a reappraisal of previous views on the systematic position and affini-
ties of the Athoracophoridae and their relation to the Succineidae.

In the Stylommatophora, the extended eye-bearing tentacle is an elongate hollow structure with an eye at
its tip. The tentacle is functionally highly contractile and retractile. In regard to retraction type, it is
inversible (introvertible, i.e., the eye of the extended tentacle can be withdrawn by a direct and initial
pulling-back of the eye, producing a progressive inversion of the tubular tentacle beginning at the distal
end and proceeding proximally, or in the words of Hyman (1967, The Invertebrates, McGraw-Hill, N. Y.,
6: 551), “turning the outside in”). Inaddition to inverting, the tentacles of non- athoracophorid species can
be partially withdrawn by contraction (in some species a contraction up to 3/4 the maximum length of the
extended tentacle before the eye has to be inverted for continued withdrawal), but in none of the species we
examined could complete withdrawal of the tentacle be accomplished without inversion. In all non-athora-
cophoran species inversion could be initiated at any stage during contraction. The tentacles of some species
are thickened as contraction continues, but in others there is little or no noticeable thickening of the ten-
tacle. Additionally, in all non-athoracophorid and non-succineid species the tentacles are covered with a
rugose dermis which is a continuation of the skin-pattern of the dorsal head-foot. This rugose pattern
extends distally to the base of the bulbous tip bearing the eye.

Tentacle retraction in the Succineidae, although similar to that described above, and on superficial in-
spection appearing identical, on closer observation can be seen to have some noteworthy differences from
the other Stylommatophora, and to have certain similarities to the athoracophorid Aneitea. The rugose
dermis of the head-foot region of the Succineidae extends onto the eye-bearing tentacles, but for only about
1/2 the length of the tentacle. There the rugose pattern abruptly stops and the remaining 1/2 of the tentacle
is smooth. The proximal tentacle tapers noticeably to the junction between the proximal rugose half and
the distal smooth half. At this point the distal half continues in an untapered rod-like fashion to the ter-
minal optical bulb. The tentacles can be contracted as in the other non-athoracophorid Stylommatophora,
i.e., on direct stimulation, the tip of the distal half of the tentacle can be inverted at any position. But,
during non-inversible withdrawal, most of the initial contraction is accomplished by the tapering rugose
basal half. On continued non-inversible retraction the distal smooth rod-like portion seems to partially
slide into the proximal part, reminiscent of Aneitea, although the terminal half of the tentacle cannot quite
completely retract into the basal half before it is necessary to invert.

Therefore, the tentacle characteristics of the Succineidae seem to be intermediate between the tracheo-
pulmonate slugs on the one hand and to the remaining Stylommatophora on the other, and hence, in this
respect, the Succineidae would seem to be an ideal ancestral type to both groups (Fig. 1, 1). Such а re-
lationship would seem to apply to various other anatomical characters as well (e.g., body surface pattern,
pedal grooves, male genitalia). Certain specialized structures in the tracheopulmonate slugs and the other
Stylommatophora could have been derived from less specialized ones in the Succineidae. Accordingly, we
conclude that the Athoracophoridae are related to the Succineidae, and perhaps should be included with
them in the same stylommatophoran suborder (Heterurethra). Other workers have reached the same con-
clusions from a study of different characters (Mirch, 1865, J. Conchyl., 13: 275, 391; Baker, 1955, Nautilus,
68(4): 109-112; Van Mol, 1967, Mem. Acad. roy. Belg., 37(5): 1-168).

l This investigation was supported by research grants GB-5601 and GB-3974 from the National Science
Foundation, Washington, D. C., and 7427 from the Foreign Currency Program, Office of International
Activities, Smithsonian Institution, Washington, D. C., U.S.A.

2Supported by a Research Career Program Award (No. 5-K3-AI-19,451) from the National Institute of
Allergy and Infectious Diseases, U.S. Public Health Service.

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260 PROC. THIRD EUROP. MALAC. CONGR.

(AD

2 5 < 4 ÉS <A

gs LA ES EB SB XX =>» «==> 28 ES ES
a

ae
SS ESTATE E NES EU
FARM SE = 3 Holopoda >

) Succineidae Y

FIG. 1. Tentacle retraction in Stylommatophora. (a) Successive stages of withdrawal and reversion of
a tentacle of Catinella vermeta (Heterurethra; Succineacea) [Michigan, U.S.A.]; (b) Successive stages of
tentacle retraction in Aneitea sp. (Heterurethra: Athoracophoracea) [New Hebrides]; (c) Leptachatina sp.
(Orthurethra; Cionellacea) [Kauai, Hawaii]; (а) Vallonia pulchella (Orthurethra: Pupillacea) [Michigan,
U.S.A.]; (e) Auriculella auricula (Orthurethra: Achatinellacea) [Oahu, Hawaii]; (f) Zonitoides nitidus
(Sigmurethra: Aulacopoda: Zonitacea) [Michigan, U.S.A.]; (g) Discus cronkhitei catskillensis (Sigmurethra:
Aulacopoda: Endodontacea) [Michigan, U.S.A.]; (h) Cryptozona bistrialis (Sigmurethra: Aulacopoda:
Ariophantacea) [Madras State, India]; (i) Opeas sp. (Sigmurethra: Holopodopes: Achatinacea) [Madras
State, India]; (j) Planispira fallaciosa (Sigmurethra: Holopoda: Helicacea) [Madras State, India]; (К)
Stenotrema leai (Sigmurethra: Holopoda: Polygyracea) [Michigan, U.S.A.]; [The tentacle on the left side
of each animal in b-k above illustrates maximum contraction of the tentacle before the eye must be in-
verted for continued withdrawal. ]; (1) Possible phylogenetic relationships of Athoracophoridae, Succineidae,
Aulacopoda and Holopoda, based on method of tentacle retraction, dermal surface pattern, and pedal grooves.
Scale lines in mm.

MALACOLOGIA, 1969, 9(1): 261-262

PROC. THIRD EUROP. MALAC. CONGR.

CYTOTAXONOMIC OBSERVATIONS IN THE STYLOMMATOPHORAN FAMILY HELICIDAE,
WITH CONSIDERATIONS ON THE AFFINITIES WITHIN THE FAMILY!

Louis J. M. Butot and Bostjan Kiauta

Research Institute for Nature Management, Zeist, and
Institute of Genetics, University of Utrecht, The Netherlands

ABSTRACT
Up until now 55 species and subspecies of Helicidae belonging to 5 subfamilies have been studied cyto-
logically. We have reexamined 20 species and subspecies. In the course of the present study 10 varieties

are dealt with for the first time. Their main cytological data are given in Table 1.

TABLE 1. New chromosome numbers in the family Helicidae

- Е A ЗЕЕ. И
Subfamily and species n | Origin
Helicellinae
Candidula
gigaxi (Pfeiffer, 1848) 27 Netherlands, Belgium
intersecta (Poiret, 1801) 26 Netherlands
Hygromiinae
Zenobiella
umbrosa (Pfeiffer, 1828) 23 W. Germany, Austria
Trichia
hispida (Linnaeus, 1758) 23 Netherlands, Belgium
W. Germany, Denmark
striolata montana (Studer, 1820) 23 W. Germany
striolata danubialis (Clessin, 1874) 23 W. Germany
Campylaeinae
Chilostoma
cingulatum baldensis (Rssm., 1839) 30 W. Germany
achates achates (Rssm., 1835) 30 Austria
planospira illyrica (Stabile, 1864) 30 W. Germany, Italy
intermedium (Férussac, 1821) 30 Italy

We could confirm the chromosome numbers given by previous authors. In Theba pisana (Müller, 1774)
and Cepaea hortensis (Müller, 1774) there was a controversy between the chromosome numbers given by
elder workers and those published recently by RAINER (1967). In both cases we could confirm the original
counts.

The true and/or pseudovariation in the chromosome numbers of Helicidae is due to the following
phenomena:

I. Supernumerary chromosomes. These are found so far only in Helix pomatia Linnaeus, 1758, and are

characterized by the following features:

a. Their occurrence is not characteristic for populations. They are present in some specimens of the
same population and not in others. If they occur, they occur in different numbers, even within one
and the same individual. We have found them in one and the same specimen in the following com-
binations: 2n + 1 supernumerary univalent (п + 1 sup. univ.), п + 3 sup. univ., n + 1 sup. bivalent,
n+ 1 sup. biv. + 1 sup. univ., n+ 1 sup. trivalent, and п + 1 sup. triv. + 1 sup. univ.

b. Supernumerary chromosomes are the smallest of the chromosome set.

They are not heteropycnotic at pachytene but they are positively heterochromatic at early diakinesis.
d. At metaphase they are usually not situated in the equatorial plane.

1 RIN-communication №. 3

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262 PROC. THIRD EUROP. MALAC. CONGR.

e. They have a delayed anaphase I.
f. They do not divide at anaphase II but follow the other chromosomes to one of the two poles.

II. Delayed pairing. In Candidula gigaxi one pair of chromosomes has a delayed pairing at diakinesis. In
many figures of early metaphase I it occurs in univalent stage. The chromosome number being in this
way 26 bivalents and 2 univalents. At late metaphase the univalents are also paired and 27 bivalents
occur in the picture. The haploid chromosome number is the number of bivalents of homologuous
autosomes. Therefore the delayed paired univalents cannot be counted separately.

Ш. Numeric variation, not due to supernumeraries or delayed pairing, has been observed only in Trichia
striolata montana. In an individual of this species (n = 23) we found one early metaphase figure with 26
elements, but in most of the figures studied 22 bivalents occurred. For the time being we are unable
to explain the nature and mechanisms causing this situation.

The haploid chromosome numbers in the family vary from 21 to 30. The distribution of the chromosome

numbers within the family and subfamilies is given in Table 2.

TABLE 2. Distribution of chromosome numbers in the subfamilies of Helicidae

Number of Number of species with chromosome number (n)
Subfamily species

E Г ] 1 |
examined PA |) PA ABS IZA 182521226
+ +
Helicellinae 13 E 4 1 | 6
Hygromiinae 10 al 8 il
Helicodontinae 1
Campylaeinae 11
Helicinae 20 3 3 4
Totals of family 55 1 Su tl 2 3 TO
aes

It is apparent from Table 2 that there is no family type number sensu WHITE (1954) in the Helicidae.
The type numbers on the other hand can be identified for the subfamilies Helicellinae (26), Hygromiinae
(23), Campylaeinae (30) and Helicinae (27). The distribution of the chromosome numbers within the family
and subfamilies is in favour of the suggestion that the family represents an unnatural group.

As far as chromosome numbers are concerned, Helicinae, Campylaeinae, and Helicellinae combined with
Hygromiinae form three cytologically well defined groups.

An evolutionary trend in the direction from 27 to 22 is apparent in the Helicinae. The total chromosome
length remains in all species approximately the same, regardless of the actual chromosome number.
From the cytological point of view the Bradybaenidae fill up the gap between Helicinae and Campylaeinae.

As to the group combination Helicellinae-Hygromiinae it is apparent that, if Rainer’s idea (1967) is
accepted and Cochlicella is brought into the tribe Monacheae, and the tribe is moved to the subfamily
Hygromiinae, the original subfamilies form, from a cytological point of view, a closed up natural unit. If,
on the other hand, there are other grounds to stick to the present organisation of the subfamilies, the two
subfamilies together form a closed up natural system, which is not allied to any other helicid subfamily
(cf. Table 2).

In our opinion Helicinae and Campylaeinae shouldbe given family rank, whereas the combination Helicel-
linae-Hygromiinae should be regarded a single independant family.

LITERATURE CITED

GRIETHUYSEN, G. A. van, 1968, Waarnemingen over de variatie van het karyotype en het gedrag in de
meiose bij de wijngaardslak Helix pomatia Linnaeus, 1758 (Gastropoda, Stylommatophora: Helicidae).
Genen en Phaenen, 12(2): 44-45.

RAINER, M., 1967, Chromosomenuntersuchungen an Gastropoden (Stylommatophoren). Malacologia, 5(3):
341-373 (with bibliography).

WHITE, M. J. D., 1954, Animal cytology and evolution, Cambridge Univ. Press, 2nd ed. 454 p.

MALACOLOGIA, 1969, 9(1): 263
PROC. THIRD EUROP. MALAC. CONGR.
SOME ASPECTS OF ADAPTIVE RADIATION IN RECENT FRESHWATER MOLLUSCS
Arthur H. Clarke
National Museums of Canada, Ottawa, Ontario, Canada
SUMMARY

Adaptive radiation is the evolutionary sequence of events leading to the differentiation and proliferation
of new taxa from a common ancestor. These events are (1) acquisition of new adaptive characters, (2) im-
migration into previously unoccupied geographical areas and (3) speciation in these new areas. Total
results are usually observable only by study of successive fossil assemblages but study of living faunas
may shed important light on the detailed nature of individual events.

In eastern North America the Lymnaeidae, Planorbidae and Sphaeriidae (here called Group 1) are pri-
marily subarctic, and the Viviparidae, Pilidae, Pleuroceridae and Unionidae (Group 2) are primarily warm-
temperate. Other families show less complete correlations with climatic zones. Important adaptive bio-
logical characteristics of the families in Group1 and Group 2, attained through prior completion of Event 1
(acquisition), correlate remarkably well with aspects of their environment and justify the formulation of
the following generalizations.

(a) Adaptive characters in Group 1 include the ability to be passively transported and the capability for
facultative self-fertilization. These are interdependent features which especially fit Group 1 to complete
Event 2 (immigration) in the north.

(B) Adaptive characters in Group 2 include brood protection, the dioecious habit, ecological specificity,
heavy shells and (in Unionidae) parasitism on fishes. These features fit Group 2 to withstand the more
intense selective predator pressures which operate in the warm-temperate region and also to complete
Event 2.

Eight subspecies of boreal freshwater gastropods appear to have evolved in eastern North America
since the Pleistocene, ¿.e., Valvata sincera ontariensis Baker, Helisoma anceps royalense Walker, H. cam-
panulatum collinsi Baker, Helisoma corpulentum vermilionense Baker, Helisoma corpulentum whiteavesi
Baker, Lymnaea stagnalis sanctaemariae Walker, Г. catascopium nasoni Baker, and L. с. preblei Dall.
All of these subspecies, except L. с. preblei, occur only in Lake Superior and in nearby adjacent portions
of the Lake Superior and Hudson Bay watersheds. The Lake Superior region, therefore, appears to be the
most active recent site for freshwater gastropod evolution in boreal eastern North America. Similar
isolative and adaptive factors associated with the unique ecology of Lake Superior may have contributed
to the partial completion of Event 3 (speciation) in all seven instances.

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MALACOLOGIA, 1969, 9(1): 264

PROC. THIRD EUROP. MALAC. CONGR.
INTRODUCED MOLLUSCS OF THE UNITED STATES
Dee S. Dundee

Department of Biological Sciences, Louisiana State University
New Orleans, Louisiana, U.S.A.

ABSTRACT

Up to the present we have knowledge of 204 species of foreign molluscs which have been reported as
being present in the continental United States. We will doubtlessly find other records as we proceed with
preparing for publication the “Introduced Molluscs of Eastern North America.” A similar work, “Intro-
duced Molluses of Western North America,” was published in 1966 by G. Dallas Hanna of the California
Academy of Sciences. The dividing line between east and west is, of course, a natural barrier, the Rocky
Mountains.

These molluscan invaders are not limited to land. Both freshwater and marine forms occur also. Over
the years various ones of these molluscs have managed to become established at least well enough so that
they have been reported as being present by various malacologists. The introduced land molluscs live in
cultivated areas or places modified greatly by human activities. Parks, nurseries, flower gardens, vege-
table gardens, orchards, etc., are the types of places where they are most likely found. Only a minority
penetrate into natural habitats. Not every species which manages to get into the country is able to become
established. Most of those which do become established do not cause much visible upset of other popula-
tions; on occasion, however, they do become serious pests.

These molluscs come from all over the world and arrive in various ways: on plants being imported, in
cargoes of fruits, household goods of our military personnel, military equipment, with shipments of tropi-
cal fishes, in luggage of tourists or as stowaways. In the words of Elton (1953), “one of the primary reasons
for the spread and establishment of species has been quite simply the movement around the world by man
of plants, especially those intentionally brought for crops or garden ornament or forestry.” It is also
likely that a few arrive through means of their own such as flying, drifting, or gradually spreading from
adjacent areas.

Two examples of species which have been introduced in recent years and which have been spreading
rapidly are an Asiatic clam and a veronicellid slug.

The clam, Corbicula fluminea, was first discovered in the United States in the Columbia River system
in the northwest in 1939. From there it spread first through California, and by 1956 it was in our desert
southwest region in irrigation canals. Ву 1961it had appeared in the Tennessee and Cumberland drainages;
in 1962 it was found in the Ohio River system; in 1963 it was in the streams in southern Louisiana; in 1964
it was taken at Vicksburg on the Mississippi River; since then it has been reported in numerous localities
in Florida. In areas whereitisfound it occurs in great numbers, and in many of these areas it is a serious
pest for companies using sand from the rivers.

Another mollusc on which there are good data is a veronicellid slug which seems to be related to y.
abevvans or У. anguistipes from Rio Grande del Sur in Brasil, but which we have yet been unable to posi-
tively identify.* It was found in the U. S. for the first time in Mobile, Alabama and New Orleans, Louisiana
in 1960. Since then it has been spreading throughout the southeastern U.S., and it is now found in great
numbers in Louisiana, Mississippi, Alabama, Florida and is still spreading. I have had the opportunity of
being on hand and watching the performance of this mollusc since its introduction. I have been able to
carefully follow its spread and have had the opportunity of studying its ecological requirements and its
morphology. This is one of the few cases where we know the date and points of entry and have been able
to follow the course of events since its introduction.

The goal is now to complete the listing of the introduced species, to determine, where possible, the
present existence of these, and then to summarize the results. My feeling is that, if all of these aliens are
registered now, and if we keep records as to their whereabouts and study some of them in detail as I and
others have already done, then we will be able to combat any uprising by them which might occur in the
future.

Generally most of these introduced forms seem to manage to find a place for themselves without causing
much visible upset of other populations; on occasion their entry has many repercussions.

*In the meantime the slugs could be identified to be Vermicella ameghini Gambetta.

REFERENCE
ELTON, C., 1953, The Ecology of Animals. Methuen & Co., Ltd., London.

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MALACOLOGIA, 1969, 9(1): 265-266
PROC. THIRD EUROP. MALAC. CONGR.

PHYSIOLOGIE DE L’ORGANE DE PERFORATION DE PURPURA (THAIS) LAPILLUS:
ROLE DE L’ANHYDRASE CARBONIQUE

Jean Fournié et Monique Chétail

Laboratoire d’Anatomie Comparée, 7 Quai St Bernard,
Faculté des Sciences de Paris, Veme, France

RESUME

L’étude histoenzymologique de l’organe de perforation de la Pourpre par la méthode de Häusler (Chétail
et Binot, 1967) montre que cette formation recele de l’anhydrase carbonique, enzyme dont la présence est
également confirmée par la méthode biochimique de Meldrum et Roughton (Chétail et Fournié, 1968). Si
l’anhydrase carbonique est vraiment responsable du percement des valves calcaires des proies de Purpura,
en utilisant le “diamox,” inhibiteur spécifique de l’enzyme, on pouvait s’attendre à un ralentissement ou à
une suppression du processus de perforation, au contraire, l’activation de l’anhydrase carbonique par le
CO2 qui est l’un des substrats de cette enzyme permettait d’espérer une accélération du phénomène de
percement (Rosenberg, Chétail et Fournié; Chétail et Rosenberg). Pour vérifier cette hypothèse, une étude
physiologique a été entreprise en ajoutant dans l’eau d’élevage des animaux, soit du “diamox” à diverses
concentrations pour les expériences d’inhibition “in vivo,” soit du CO2 pur ou deux mélanges différents de
CO» + O2 pour les essais d’activation. Pour interpréter les résultats expérimentaux, nous nous sommes
constamment référés aux observations effectuées sur des animaux témoins élevés en eau de mer normale;
dans ces conditions, les tentatives de perforation aboutissent toujours à un résultat positif, soit: 50% de
trous complets, 33% de trous incomplets et 17% d'empreintes.

Expériences d’inhibition “in vivo”: pour les faibles concentrations en “diamox” (10-3 et 3.10-3М}, on
observe une diminution du nombre des trous complets dans le premier cas et leur disparition totale dans
le second; par contre pour ces deux concentrations, on note une élévation du nombre des empreintes que
l’on peut interpréter ainsi: par suite del’inhibition de la majeure partie de l’enzyme au niveau de l’organe
de perforation, les Pourpres qui normalement auraient dû effectuer un trou complet ne peuvent plus
réaliser qu’une empreinte. Pour les concentrations plus fortes en “diamox” (5.10-3М et 7.10-3M), on
obtient une méme inhibition totale de l’enzyme, toutes les tentatives de perforation restant sans résultat,
pour un temps de fixation pourtant beaucoup plus élevé que celui noté chez les témoins. Si Гоп replace
les animaux “diamoxés” en eau de mer normale et que l’on observe leur comportement, on constate que
l’inhibition de l’anhydrase carbonique est réversible et que ce sont les Pourpres soumises aux doses de
“diamox” les obligeant a un jeúne absolu, qui nontrent le plus d’activité lors de leur remise dans leur
milieu normal.

Expériences d’activation “in vivo”: L'activation de l’anhydrase carbonique par le CO2 pur se traduit par
une augmentation du nombre des trous complets (égal en fait а la somme de trous complets et incomplets
dénombrés chez les témoins), une diminution du nombre des trous incomplets (égal au nombre des em-
preintes chez les témoins) et la disparition des empreintes; on peut interpréter ainsi ces résultats: par
suite de l’activation de l’anhydrase carbonique au niveau de l’organe de perforation, les Pourpres qui nor-
malement n’auraient effectué qu’un trou incomplet ou une empreinte ont pu réaliser ä la place, soit un
trou complet dans le premier cas, soit un trou incomplet dans le second. Par contre, le temps moyen de
fixation nécessaire pour obtenir un trou complet ou incomplet est supérieur a celui observé chez les
témoins, par suite de l’effet anesthésique de ce gaz. Pour éliminer cet effet, nous avons utilisé deux
mélanges gazeux contenant des proportions différentes de gaz carbonique et d’oxygene; les résultats ob-
tenus montrent que l’activation de l’anhydrase carbonique est proportionnelle à la quantité de CO» dissoute
dans l’eau de mer des élevages: C'est ainsi qu'avec le mélange 5% CO» + 95% Og on obtient deux fois plus
de trous complets que chez les témoins еп un temps légérement plus court, tandis qu’avec le mélange 95%
CO2 + 5% Og on en compte jusqu’ a trois fois plus, et ceci en un temps nettement plus bref: le CO2
facilite donc considérablement le percement. L’anhydrase carbonique catalyse la réaction réversible:
COg + Н2О => H2C03 > H* + HCO3; l’action du gaz carbonique peut alors s’expliquer ainsi: en présence
d’une teneur en CO), accrue par rapport aux conditions normales, la reaction catalysee par 1'anhydrase
carbonique dans le sens de 1'hydratation du CO, est favorisee; il en résulte une production supplémentaire
d'ions H* responsable de la dissolution plus rapide du carbonate de calcium des valves de Lamellibranches
par les Pourpres élevées en eau de mer enrichie en CO».

En résumé, ces expériences d’inhibition et d'activation “in vivo” prouvent que l’anhydrase carbonique
décelée dans l’organe de perforation est l’agent impliqué lors du percement des valves calcaires des
proies de Purpura (That's) lapillus; en outre, les résultats obtenus par l’action du CO» apportent des pré-
cisions sur le mécanisme chimique de la réaction en cause. Il est probable que les ions H* émis sous
l’action de l’anhydrase carbonique sont échangés contre desions Ca** dont la concentration est tres élevée

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266 PROC. THIRD EUROP. MALAC. CONGR.

pendant l’activité de l’organe de perforation, comme nous l’avions mentionné auparavant (Chétail et Binot
1967), mais ce point de vue n’a pu encore être confirmé; cependant, il n'est pas impossible qu’un cation
autre que Cat* soit aussi impliqué dans ces échanges.

En résumé, nos résultats montrent clairement que l’acidité produite au niveau de l’organe de perfora-
tion, sous l’influence de l’anhydrase carbonique, est responsable de la dissolution du СаСО 3 des valves
des Lamellibranches par la Pourpre et que cette activité anhydrasique s'accompagne d’échanges ioniques
complexes dont la nature reste a préciser.

REFERENCES

CHETAIL, M. € BINOT, D., 1967, Présence et róle de l’anhydrase carbonique dans l’organe accessoire
de perforation de Purpura lapillus L. С. В. Acad. Sci., 264(7): 946-949,

CHETAIL, М., BINOT, D. & BENSALEM, M., 1968, Organe de perforation de Purpura lapillus L. (Muricidé):
histochimie et histoenzymologie. Cah. Biol. Mar., 9: 13-22.

ROSENBERG, A. J., CHETAIL, М. € FOURNIE, J., 1968, Intervention de l’anhydrase carbonique dans le
mécanisme de perforation des valves de Lamellibranches par Purpura (Thats) lapillus L. (Gastéropode
Prosobranche Muricidé). С. В. Acad. Sci., 266: 944-947,

CHETAIL, M. & ROSENBERG, A. J., 1968, Carbonic anhydrase and shell boring mechanism by Purpura
(Thats) lapillus L. Am. Zool., 8: 802.

CHETAIL, М. € FOURNIE, J., 1968, Shell boring mechanism in the gastropod, Purpura (Thats) lapillus:
a physiological demonstration of the role of carbonic anhydrase in the dissolution of CaCO3. Am.
Zool., 9(3): 232-237.

MALACOLOGIA, 1969, 9(1): 267
PROC. THIRD EUROP. MALAC. CONGR.
DISTRIBUTION AND ECOLOGY OF HELICODONTINAE IN NORTHERN ITALY
Alberto Girod
Milano, Italy
ABSTRACT

The wood-inhabiting Mollusca and other species with similar microenvironmental exigencies, are not so
well fit as the calcareous rock-inhabiting species for a biogeographic detailed study of a region. However,
an attempt is carried out in this work with some species of the subfamily Helicodontinae. In Northern Italy
Drepanostoma nautiliforme PORRO is distributed only in Piedmont and the western side of Lombardy. This
small snail with a merely woodland ecology seems to have a residual distribution, for in the Pleistocene
it lived in the Northern Alps, too, as we can see from the Quaternary fossils. Also, Helicodonta obvoluta
(Müller) is a typical form of the woodland communities and in connection with the progressive reduction of
the deciduous wood tends to leave those parts of Lombardy that were occupied immediately after the Würm
post-glacial period. Therefore, it is more frequent in rather undisturbed zones at the head of the Prealps
valleys and at the top of the mountains. This fact causes a general rarefaction of the area occupied by the
species which, in many cases, presents clearly disjointed distribution. Helicodonta angigyra (Ziegler)
having a higher ecological valence can profit alone by environmental conditions arisen in the historical
times, connected with wood degradation, human trade, and consequently a new vegetable and morphologic
aspect of so many Lombard zones.

MALACOLOGIA, 1969, 9(1): 267
PROC. THIRD EUROP. MALAC. CONGR.

DIE GATTUNG TRISSEXODON PILSBRY 1
E. Gittenberger
Rijksmuseum van Natuurlijke Historie, Leiden, The Netherlands
ZUSAMMENFASSUNG

In der Gattung Trissexodon (Gastropoda, Pulmonata, Helicodontinae) werden zwei rezente und zwei
fossile Arten untergebracht. Von den beiden rezenten Arten, T. constrictus (Boubée), dem Genotypus aus
den westlichen Pyrenäen und T. quadrasi (Hidalgo), aus Ost-Spanien, konnten einige Tiere anatomisch
untersucht werden.

Es stellte sich heraus, dass die beiden rezenten Arten durchaus nicht nahe verwandt sind und in zwei
verschiedene Gattungen gehören. Die von Ortiz de Zarate (1943: 82) gegebene Abbildung der Genitalorgane
von T. constrictus erwies sich als unrichtig.

Für Helix quadrasi wird eine neue Gattung aufgestellt. (Siehe E. Gittenberger, 1968).

Ausserdem wird auf vier unbenannte Arten aus Jugoslawien hingewiesen, die im Gehäuse T. constrictus
etwas ähnlich sehen und in einigen Sammlungen unter Trissexodon eingeordnet wurden. Die Anatomie ist
unbekannt. Es handelt sich hier um Spelaeodiscinae. Für die vier neuen Arten wird eine neue Gattung mit
zwei Untergattungen aufgestellt. (Siehe E. Gittenberger, 1969).

Von den beiden fossilen Arten wird eine, Polygyra plioauriculata Sacco, in Protodrepanostoma Germain
zurückverwiesen. Die andere, Helix subconstrictus Souverbie, kann in der Gattung Trissexodon bleiben.

LITERATUR

GITTENBERGER, E., 1968, Zur Systematik der in die Gattung Trissexodon Pilsbry (Helicidae, Helico-
dontinae) gerechneten Arten. Zool. Meded. Rijksmus. Nat. Hist. Leiden, 43(13): 165-172.

GITTENBERGER, E., 1969, Beiträge zur Kenntnis der Pupillacea; Die Spelaeodiscinae. Zool. Meded.
Rijksmus. Nat. Hist. Leiden, 43(22): 287-306.

ORTIZ DE ZARATE, A., 1943, Observaciones anatömicas y posiciön sistemätica de varios Helicidos
espanoles, 1. Bol. Real Soc. Esp. Hist. Nat., 41(1/2): 61-83.

lin extenso as thesis. (267)

MALACOLOGIA, 1969, 9(1): 268
PROC. THIRD EUROP. MALAC. CONGR.
BEITRAGE ZUR OKOLOGIE UND BIOLOGIE DER PISIDIEN IM LUNZER UNTERSEE
Gerhard Hadl
1. Zoolog. Institut, Universittit Wien, Austria
ZUSAMMENFASSUNG

Die häufigsten, aber dabei am wenigsten bekannten Süsswassermuscheln sind die Sphaeriidae. Sie fehlen
in fast keinem Biotop, weder in grossen Gewässernnoch in kleinen Wasseransammlungen. Die Verbreitung
ist grossteils nicht geographisch gebunden und Wasserscheiden sowie Meerengen bilden keinerlei Hindernis
für die Ausbreitung, die hauptsächlich endo- und ektozooisch durch Wassergeflügel, Fische, Insekten u.a.
erfolgt. Für das Vorkommen sind lediglich klimatische und ökologische Faktoren ausschlaggebend.

Obwohl der Lunzer Untersee (Seehöhe 608 m, max. Tiefe 33 m), ein Voralpensee, faunistisch als sehr
gut erforscht gelten kann, finden wir Angaben über die Weichtierfauna sehr selten. Über Pisidien ist
meines Wissens überhaupt nichts bekannt.

Es ist nun sowohl die räumliche Verteilung der verschiedenen Arten im See, als auch die jahreszeit-
lichen Unterschiede in der Besiedlung von Interesse.

An Hand der Besiedlungsverhältnisse lassen sich drei Zonen unterscheiden. Das Litoral von 0-8 m als
Litoral I, die Zone zwischen 8 und 12 m als Litoral II, und darunter das Profundal. Die Tiefenverteilung
der verschiedenen Arten dürfte hauptsächlich von der Temperatur und vom Substrat abhängig sein. Die
Substratverhältnisse lassen sich relativ einfach charakterisieren. Zwischen 0 und 8 m, dem Litoral I,
finden wir sehr kalkreichen Schlamm und Seekreide mit grossen Mengen von Molluskenresten. Diese
Zone weist einen geringen Makrophytenbewuchs auf. Von 0-2 m überwiegt Phragmites, daran schliessen
sich einige Potamogeton-Arten an. Vor allem diese Potamogetonzone wirkt infolge einer ziemlich starken
biogenen Kalkausscheidung sehr limitierend auf die Pisidienfauna. Diese Kalkausfällung verursacht einen
ziemlich starken Regen, der die Tiere durch Verschüttung in ihren Lebensgewohnheiten empfindlich stören
dürfte. Wir finden hier inquantitativen Probeneine sehr geringe Individuendichte. An diese Zone schliesst
sich das Litoral II zwischen 8 und 12 man, wo wir schon Feinschlamm mit Eisenausfällungen antreffen,
die sich dann bis in die tiefsten Stellen des Sees erstrecken. An Makrophytenbewuchs tritt nur noch
Fontinalis auf. Die Profundalregion besteht aus ziemlich einheitlichen Feinschlammsedimenten.

Die sieben Pisidiumarten verteilen sich nun wie folgt: Pisidium nitidum, P. milium, P. lilljeborgi und
P. subtruncatum im Litoral I, P. conventus und P. personatum (im den oberen Teilen) im Profundal. Im
Litoral II findet sich mit P. nitidum, P. casertanum, P. lilljeborgi und P. conventus die artenreichste
Fauna. Dieses Gebiet ist zum Teil als Misch- und Überschneidungsgebiet aufzufassen. Von diesen 7
Arten überwiegen nun zwei in zum Teil beträchtlichem Masse. P. conventus als charakteristische Pro-
fundalform bildet grossteils eine einartige Population und wirdnur in den oberen Teilen von P. personatum
begleitet, welches in anderen Seen manchmal noch weit tiefer als P. conventus geht und dieses verdrängt,
was aber hier nicht der Fall ist. P. conventus ist eine typische Kaltwasserart, die in unseren Breiten auf
das Profundal von Seen beschränkt bleibt und nur in höheren geographischen Breiten bis ins seichte Litoral
reicht. Zu dieser Kaltstenothermie dürfte sich noch eine Rheophobie gesellen, die es den Tieren nicht
gestattet, sich auch in kalten Fliessgewässern anzusiedeln, sowie gewisse Ansprüche an das Substrat. Die
Temperatur im Biotop erreicht und überschreitet selten 12° Celsius. Im Litoral I überwiegt bei weitem
Р. nitidum. Die anderen Arten treten zahlenmässig stark zurück.

Die zeitlichen Änderungen der Besiedlungsdichte sind hauptsächlich von den Lebenszyklen der einzelnen
Arten, wann und wie oft Nachkommen herangebildet werden, abhängig. Bei Pisidium nitidum werden die
meisten Jungtiere im Juli und August frei. Zu dieser Zeit erreicht die Temperatur im Biotop ihr Maxi-
mum. In den tieferen Zonen, die von P. conventus bewohnt werden, sind die Temperaturverhältnisse relativ
ausgeglichen. Man findet bei P. conventus sowohl in 10 als auch in 20 m Tiefe das ganze Jahr hindurch
trächtige Tiere. Die Brutperioden sind bei dieser Art nicht zeitlich korreliert, sondern erfolgen das ganze
Jahr hindurch nach Erreichen einer bestimmten Körpergrösse. Neben diesen Populationszunahmen, die
sich mehr oder minder durch die Brutperioden erfassen lassen, treten nun noch Abnahmen auf. Diese
können sowohl durch Parasiten als auch durch Räuber verursacht werden. Darüber ist allerdings noch zu
wenig bekannt, um sichere Aussagen zu machen.

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MALACOLOGIA, 1969, 9(1): 269-270

PROC. THIRD EUROP. MALAC. CONGR.

CONTRIBUTION TO THE KNOWLEDGE OF THE CYTOTAXONOMIC CONDITIONS
IN THE STYLOMMATOPHORAN SUPERFAMILY ZONITACEA!

Bostjan Kiauta and Louis J. M. Butot

Institute of Genetics, University of Utrecht, and
Research Institute for Nature Management, Zeist, The Netherlands

ABSTRACT

PERROT (1938), HUSTED & BURCH (1946), BEESON (1960), LAWS (1966) and RAINER (1967) have pub-
lished on the cytology of 16 species of the families Zonitidae, Milacidae and Limacidae. In the course of
the present study 7 species of the families Vitrinidae and Zonitidae were examined. None of them have
been previously studied cytologically. The haploid chromosome number n = 31 was found in all Vitrinidae.
The same haploid number occurs in the zonitid Aegopinella nitidula, whereas Oxychilus cellarius and O.
dvapavnaudi have 24 bivalents (2n = 48 in the latter species). Their main cytological data are given in
Table 1.

TABLE 1. New chromosome numbers in the superfamily Zonitacea

Family and species
Vitrinidae
Vitrina pellucida (Miller, 1774)

Vitrinobrachium breve (Ferussac, 1821)

Netherlands, W. Germany
Netherlands, W. Germany

Eucobresia diaphana (Draparnaud, 1805) Netherlands
Phenacolimax major (Ferussac, 1807) Netherlands
Zonitidae

Aegopinella nitidula (Draparnaud, 1805) Netherlands
Oxychilus cellarius (Miller, 1774) Netherlands

Oxychilus draparnaudi (Beck, 1837) Netherlands

The family numeric pattern is clear in the Vitrinidae only (n = 31). In the Zonitidae the chromosome
numbers vary greatly: n = 20 in 1 species of Vitreinae; n = 24 in 2 species, 30 in 2 species and 31 in 2
other species of Zonitinae; in the Gastrodontinae п = 30 or about 30 in Zonitoides nitidus (Muller, 1774)
and Z. excavatus (Alder, 1830) according to our photographs, which, however, do not permit a final decision.

In the Milacidae the family type number is probably 33. In the Limacidae 2 species have n = 24, 4 species
n = 30 and 3 species have 31 bivalents.

As to the trend of the karyotypic evolution within the superfamily, it is probably of importance that in
the high-n complements (30-31) the chromosomes are of gradually decreasing magnitude, whereas the
low-n karyotypes show two exceptionally long pairs. This situation seems to suggest several centric fusions
resulting in a reduced chromosome number and exceptional relative length of some pairs of chromosomes.
It is particularly clear in the species Aegopinella - Oxychilus and probably also in Limax - Malacolimax,
Lehmannia.

The direction of the evolution from the high to the low chromosome number is also apparent in the
stylommatophoran family Helicidae. Apart of the variation in chromosome number, the morphology of the
karyotype is extremely uniform within single zonitacean families. This applies to the relative length of
the elements, chiasma frequency, chiasma morphology, and the number of notably bigger and smallest
elements. Nevertheless, as far as our material is concerned, minute, but clear and constant karyotypic
differences enable cytotaxonomic separation of Vitrina pellucida, Vitrinobrachium breve, Eucobresia
diaphana and Phenacolimax major.

1RIN-communication No. 4

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270 PROC. THIRD EUROP. MALAC. CONGR.

LITERATURE CITED

BEESON, G. E., 1960, Chromosome numbers of slugs. Nature, London, 186: 257-258.

HUSTED, L. & BURCH, P. R., 1946, The chromosomes of polygyrid snails. Amer. Nat., 80: 410-429.

LAWS, H. M., 1966, The cytology and anatomy of Oxychilus alliarius (Miller) (Mollusca, Zonitidae) a new
introduction to South Australia. Rec. S. Austr. Mus., 15: 257-260.

PERROT, M., 1938, Etude de cytologie comparée chez les gasteropodes pulmonés. Rev. Suisse Zool.,
45: 487-566.

RAINER, M., 1967, Chromosomenuntersuchungen an Gastropoden (Stylommatophora). Malacologia, 5(3):

341-373.

MALACOLOGIA, 1969, 9(1): 271-272
PROC. THIRD EUROP. MALAC. CONGR.
REMARKS ON THE BIOLOGY OF ABYSSAL BIVALVES
J. Knudsen
Zoological Museum, Copenhagen, Denmark
ABSTRACT

The study is based mainly on the collection of bivalves obtained by the “Galathea” deep-sea expedition
(1950-52) at depths greater than 2000 m, 127 samples from 50 stations, a total of 1500 specimens. The
collection comprises 76 species, of which 36 (besides 11 from the hadal zone, below 6000 m) are described
as new. Three species are represented by valves only, no less than 27 of the 76 species are represented
by a single specimen, and only 19 species are represented by 10 or more specimens. Besides the “Galathea”
collection a smaller number of samples from other sources have been included, so that altogether 159
samples with some 1700 specimens, distributed over 91 taxa, have been studied in some detail.

During the study numerous samples from the earlier deep-sea expeditions have been examined, partly
to solve taxonomic problems, but also in an attempt to determine whether a given species is known from
specimens alive at capture or from empty valvesonly, as this is frequently not mentioned in the literature.

Altogether I have examined about 75% of the existing samples of abyssal bivalves, in addition to several
hundred samples of bathyai bivalves. Taxonomic revision of a number of species and the exclusion of
numerous records of shallow-water bivalves only represented by empty vaives has considerably reduced
the number of species of bivalves known from depths greater than 2000 m. Including the 36 new species ob-
tained by the “Galathea” expedition, altogether about 230 species are known from depths between 2000 and
6000 m. _ Thirty-eight are bathyal species which penetrate into the abyssal zone (mostly upper part),
leaving about 192 species as an “endemic” abyssal bivalve fauna. It should be emphasized, however, that
the upper limit of the abyssal zone is not sharp, and varies in different parts of the World Ocean, although
it appears that the upper limit of a number of comparatively well-known species is located between 2000
and 2500 m depth.

Our knowledge of the abyssal bivalves is still very deficient. This is, for instance, shown by the fact
that 122 of the 192 species have only been recorded once, and only 11 species have been recorded 10 times
or more. It should also be noted that only about 270 samples of abyssal bivalves have been obtained, and
only 80 samples with bivalves have been obtained below 4000 m (the average depth of the World Ocean).

The horizontal distribution of some species has been worked out: Malletia cuneata (Jeffreys) is known
from the Arctic Ocean (at great depths only), and the World Ocean including the Antarctic and the E.
Pacific. It appears to be the only species common to the Arctic Ocean and the abyssal depths of the World
Ocean. Arca orbiculata Dall is found throughout the World Ocean, including the E. Pacific, and a similar
distribution is found in Acar asperula (Dall), although no records are at hand from the easternmost part
of the E. Pacific (Panama region). Abra profundorum (Smith) is known from the Atlantic, Indian Ocean
and W. Pacific, while no records are available from the E. Pacific. In one case it has been found that one
subspecies, Limopsis pelagica pelagica Smith, is widely distributed in the Atlantic and Indian Oceans (but
apparently absent from the W. Pacific). In the E. Pacific it is replaced by L. pelagica dalli Lamy. A
similar type of distribution has been found in Poromya tornata (Jeffreys) (Atlantic and Indian Oceans),
which is replaced in the E. Pacific by Р. perla Dall. Propeamussium meridionale (Smith) is known only
from the Pacific (including the E. Pacific) andthe Indian Oceans, but appears to be absent from the Atlantic,
while Cyclopecten undatus (Verrill & Smith) is known mainly from the Atlantic (with one record from the
Indian Ocean). Finally, Муопета undata (Verrill) is found in both the Atlantic and Indian Oceans, but not
in the Pacific. Nearly all the species referred to above are known from between 10 and 40 records and
most of them are known from a depth below 4000 m.

In the distribution of the bivalves outlined above, there is no indication of either an Atlantic subregion
versus an Indo-pan-Pacific region as has been suggested by Ekman (1953) or an Atlantic-Indian subregion
versus a Pacific subregion (Madsen, 1961), although a corresponding distribution has been found in a few
individual species.

In a few species the size of the samples made a closer study of the intraspecific variation possible.
This is particularly the case inthe following species: Malletia cuneata, Acar asperula, Limopsis pelagica
(both subspecies) Arca orbiculata, Propeamussium meridionale and Abra profundorum. In the three last-
mentioned species only a very small range of variation was observed, but the three first-mentioned species
varied widely in many characters (shape of the shell, dentition of hinge, etc.). However, no geographical
variation could be observed, nor was there any variation which could be correlated with the depth. It
appeared that whenever larger samples were present, the species’ whole range of variation would generally
be found within the sample.

In several groups (Isopoda, Amphipoda) a very limited distribution has been found in many abyssal

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272 PROC. THIRD EUROP. MALAC. CONGR.

species. Apparently many species are confined to a single basin (“basin endemism”). Clarke (1962) ad-
vocated the generally restricted distribution of abyssal non-cephalopod molluscs, stating that the known
mean geographical spread for most species is 2.0 ocean basin. The present survey has established a very
wide distribution for many species. The alleged “basin endemism” is probably only due to the fact that
most species (in case of the bivalves 64%) have only been recorded once. Additional records may consid-
erably extend the known distribution of numerous species.

The composition of the abyssal bivalve fauna differs from that of other areas by the high proportion of
Protobranchia (49%) and of Septibranchia (25%), while all other families (with the exception of the Pec-
tinidae, 7%) are very poorly represented. The number of abyssal bivalve species appears to be roughly
twice the number of species of the arctic fauna and the antarctic fauna, living under the same temperature
conditions. However, it seems most likely that numerous abyssal species of bivalves still remain undis-
covered.

A detailed account is in print.

LITERATURE CITED

KNUDSEN, J. (In press). The systematics and biology of abyssal and hadal bivalvia. Galathea Report
vol, PL:

MALACOLOGIA, 1969, 9(1): 272

PROC. THIRD EUROP. MALAC. CONGR.

FLAPPING BEHAVIOR IN THE LAMPSILINAE (PELECYPODA: UNIONIDAE):
SOME ASPECTS OF ITS NEUROBIOLOGY

Louise Russert Kraemer
Department of Zoology, University of Arkansas, U.S.A.
ABSTRACT

Though apparently peculiar to the Lampsilinae, flapping behavior nonetheless involves portions of the
behavior repertoire found in many bivalves. Coordinated functions of the foot, marsupium, valves, and
siphons during flapping behavior greatly alter the supposed normal relationships between the body and
shell. Most striking feature is the rhythmical movement of the mantle flaps. The mantle flaps, which have
eyespots and “tails,” are remarkably fishlike in appearance, and constitute a permanent anatomical
feature of the mature female, as an extension of the inner lobe of the mantle edge, just anteroventrad to
the branchial siphons.

In the present paper: (1) Flapping behavior and evidence (from field and aquarium studies, as well as
anatomical investigations) for its role as a spawning mechanism were described briefly.

(2) The gross and microscopic neuroanatomy of siphonal and flap regions of Lampsilis ventricosa,
L. fasciola, and L. siliquoidea were compared. An unusual, small but conspicuous mantle ganglion was
found to be consistently present in both male and female specimens of these three species. This mantle
ganglion is located inside the mantle edge, nearly in line with the posterior pallial nerve, and at the point
where the pulsing movements of the mantle flaps are initiated during flapping behavior. Further, the con-
nections which this ganglion makes with nerves which extend to the visceral ganglion, to the posterior
pallial nerve and distally into the mantle flap, suggest that the mantle ganglion may be a significant neuro-
anatomical entity in mantle flap movements.

(3) Experimental evidence was presented to show that certain changes in light intensity can account for
diurnal changes in flapping behavior which have been monitored in Lampsilis ventricosa.

(4) An hypothesis was offered concerning one possible role of the flap movements per se in the spawning
process, i.e., that the bellows-like movement of the mantle flaps over the gravid ovisacs of the marsupia
aids in the suspension of the recently shed glochidia in the water, and thus helps to effect their necessary
contact with the fish host.

A detailed account of some of the work on which the foregoing findings are based, is to be published in a
regular issue of Malacologia.

MALACOLOGIA, 1969, 9(1): 273
PROC. THIRD EUROP. MALAC. CONGR.
THE ARTERIAL GLAND OF AGRIOLIMAX RETICULATUS (PULMONATA: LIMACIDAE)
A. A. Laryea

Department of Zoology, University College of North Wales,
Bangor, Caernarvonshire, U. K.

ABSTRACT

The arterial gland of Agriolimax reticulatus consists of irregularly shaped masses of opaque whitish
tissue situated discontinuously along the distal portion of the cephalic artery and along its branches,
especially the posterior pedal artery. The tissue is divided into lobules with thick bundles of collagen
fibres between. Each lobule is composed of irregular cells and intercellular channels, in some cases
leading directly to the edge of the gland. Intracellular ducts connect with the intercellular channels.

Granules occur within the cells and these appear to be of two main types. Each A type granule has an
amorphous, moderately homogenous, electron dense content which normally completely fills its limiting
membrane. These granules staindeeply with Toluidine blue. B type granules are less electron dense, their
contents have a flocculent appearance and they stain only lightly or moderately with Toluidine blue. These
granules contain a variable number of irregular spaces.

The granules release their contents into the intercellular channels directly or into the intracellular
ducts.

Histochemical tests for carbohydrates, certain hydroxysteroid dehydrogenases, calcium, copper and acid
phosphatase were all negative. Tests for lipid were only faintly positive. The secretory granules, however,
stained intensely with Bromophenol blue and gave positive reactions to tests for tyrosine and aspartic and
glutamic acids. Tests for SS and SH groups were only weakly positive.

Chromatographic analysis for steriods gave negative results,

Microprobe analysis revealed an accumulation of copper within the arterial gland tissue but it was not
possible to localise its position within the cells.

As copper and protein were both present within this gland it was decided to test the arterial gland tissue
for haemocyanin. Rabbit antiserum to Helix aspersa haemocyanin was prepared and found to cross react
with Agriolimax reticulatus haemocyanin. Immunoelectrophoresis performed using this antiserum and
homogenised arterial glands from Agriolimax reticulatus gave negative results.

The arterial gland in Agriolimax veticulatus contains secretion at all stages of reproductive develop-
ment. The size of the gland is extremely variable between individuals but neither size nor histology could
be related to reproductive development.

Of a number of gastropod species examined for the presence of the gland, tissue with a similar appearance
to the arterial gland of Agriolimax reticulatus, when stained with Azan, was found in 4: A. caruanae, Limax
flavus, Oxychilus alliavius, O. cellarius.

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MALACOLOGIA, 1969, 9(1): 274
PROC. THIRD EUROP. MALAC. CONGR.
STUDIES ON THE ODOUR OF OXYCHILUS ALLIARIUS (PULMONATA, ZONITIDAE)
D. C. Lloyd
Department of Zoology, University College of North Wales, Bangor, U. K
ABSTRACT

Oxychilus alliarius produces an odour indistinguishable from that of garlic. The general opinion of
naturalists is that it is a defensive adaptation produced on irritation.

Experiments at isolating portions of the body showed the odour to originate from the right side of the
mantle near to the pneumostome. It is liberated on stimulation in a characteristic brown viscous mucus.
Analysis of this mucus showed it to be a single entity, a protein/carbohydrate complex, especially rich in
protein. Inorganic material constituted eight percent of the dry weight and is probably mainly calcium
carbonate, and this may be responsible for the marked viscosity of the mucus.

A gas liquid chromatographic analysis of the volatiles produced on irritation of Oxychilus alliarius
showed one very large peak and a few minor ones. The main peak was identified as propyl mercaptan.

The cells responsible for the odour are grouped into a small cluster and react very positively to histo-
chemical tests for disulphide and sulphydryl groups. A 3-dimensional picture produced from serial sec-
tions of the region showed that the odour gland cells discharge into a groove which is part of the pneumo-
stome channel although somewhat separate from the main lumen. Ultrastructurally the odour gland cells
have a large central vacuole in which accumulates the secretion. The cytoplasm is peripheral and charac-
terised by many golgi bodies and their associated vesicles. The cells are invested with muscle fibres for
discharge of the secretion.

Sulphur-35 in the diet was demonstrated autoradiographically to be incorporated into the odour gland.
There was a considerable time lag in the appearance of the label in animals which had not been previously
stimulated and therefore had undepleated odour reserves.

Experiments to determine the function of the odour showed that it was not a sex attractant, nor did it
have antibiotic properties. Time-lapse ciné photographic experiments using hedgehogs as predators showed
a statistically significant rejection of Oxychilus alliavius in favour of other non-garlic Oxychilus spp.
Therefore the odour seems to have a defensive function against small mammals, certainly at least against
hedgehogs.

*Present Address: Zoology Department, University College, Cardiff, U. K.

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MALACOLOGIA, 1969, 9(1): 275-276
PROC. THIRD EUROP. MALAC. CONGR.

REMARQUES SUR L’HERMAPHRODISME JUVENILE
DE QUELQUES VENERIDAE (BIVALVIA)

Albert Lucas
Laboratoire de Zoologie, Faculté des Sciences, Brest, France

Sur de jeunes exemplaires de Bivalves, on découvre, avant que la glande génitale ne soit fonctionnelle,
une structure particuliére des éléments germinaux, ой 1’оп peut déceler quelques cellules sexuées. Cette
manifestation précoce de la sexualité est extrêmement fugace, ce qui explique qu’elle soit restée longtemps
ignorée. Le présent travail rend compte des résultats que j’ai obtenus sur un certain nombre de Veneridae:
Dosinia exoleta et Venus verrucosa, originaires de Locmariaquer (Bretagne, France), Venus striatula
originaires de Morgat (Bretagne), Mercenaria mercenaria originaires de Milford (U.S.A.),Venerupis
decussata originaires de Plestin (Bretagne), Venerupis pullastra, V. aurea et V. rhombofdes originaires
de Brest (Bretagne).

TECHNIQUES ET METHODES
Pour chaque exemplaire des coupes histologiques sont effectuées dans la région intéressante, c’est-a-
dire entre la région péricardique et la base du pied. On y trouve des tubules qui pénétrent a travers le
conjonctif en longeant l’anse intestinale et en contournant les faisceaux musculaires de la base du pied.
Or dans ces tubules, qui sont des éléments transitoires, il existe une manifestation sexuelle qui se traduit
par le développement d’un nombre limité de gamétes.

RESULTATS

Les résultats obtenus sont résumés dans le tableau suivant.

A A A
E Taille | 56%
Especes Date Bini inde- р gd © y Total
termine

Dosinia exoleta mars 8-12 3 1 5 2 11
Venus verrucosa mars 6-21 3 4 2 1 10
Venus striatula toute l’annee 3-12 5 4 1 12 22
Mercenaria mercenaria mai 5-10 13 9 3 2 27
Venerupis decussata février 12-21 5 9 9 3 26
Venerupis decussata septem. 10-20 0 5 2 8 15
Venerupis pullastra mars 7-20 3 E 0 0 7
Venerupis aurea mars 9-20 6 12 2 0 20
Venerupis rhomboides mars 10-19 12 9 3 0 24

On doit considérer ces résultats comme un sondage préliminaire, car le nombre d’exemplaires examinés
est relativement faible, notamment pour Venerupis pullastra (7), Venus verrucosa (10), Dosinia exoleta
(11). Enfin pour Venerupis decussata où 41 exemplaires ont été étudiés, il apparaît une différence notable
entre septembre et février pour unmêmebiotope: Plestin. Ceci pose le problème des variations possibles
au cours du cycle annuel. Remarquons à ce propos que la sexualité juvénile semble se manifester toute
l’année, même chez les espèces où le cycle de reproduction des adultes est limité dans le temps.

MODALITES DE L’HERMAPHRODISME JUVENILE

Les cas d'hermaphrodisme juvénile que j'ai décelés chez les Veneridae sont de trois types:

1) Ovocytes prévitellogéniques et spermatocytes (et parfois, spermatides). C'est le cas le plus fréquent

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276 PROC. THIRD EUROP. MALAC. CONGR.

chez Venerupis decussata, Venus verrucosa, Dosinia exoleta.

2) Ovocytes prévitellogéniques et présence de spermatozoïdes (ce qui n’exclut pas l’existence de sper-
matocytes et de spermatides) rare chez Venerupis decussata, fréquent chez Venus striatula.

3) Ovocytes a vitellus (accompagnés ou non d’ovocytes prévitellogéniques) et présence de spermatozoides.
Vu chez Venus striatula et Mercenaria mercenaria.

En outre, j'ai observé chez У. decussata en particulier, des ovocytes plus ou moins désagrégés à côté
de spermatozoides intacts. Toutefois, ces structures étant mal caractérisées, je ne les ai pas comptées
au nombre des hermaphrodismes. Enfin, il faut noter la présence trés fréquente d’amoebocytes parmi les
éléments sexués. Ceci est en relation avec le caractére fugace et abortif de la sexualité juvénile.

CONCLUSION

La sexualité juvénile existe chez toutes les especes étudiées. L’hermaphrodisme juvénile existe mais
semble faible pour Dosinia exoleta, Mercenaria mercenaria, Venus verrucosa. Par contre, il est bien
marqué pour Venus striatula et Venerupis decussata.

L’hermaphrodisme juvénile a déja été signalé chez Mercenaria mercenaria (Loosanoff, 1937), Venerupis
decussata (Lucas, 1968) et Venus striatula (Lucas, 1965, 1966). Chez cette derniére espéce Ansell (1961)
avait en outre observé de l’hermaphrodisme postlarvaire. A notre connaissance, les autres espéces n’ont
fait l’objet d’aucune étude sur la sexualité juvénile.

BIBLIOGRAPHIE

ANSELL, A. D., 1961, The development of the primary gonad in Venus striatula (Da Costa). Proc. Malacol.
Soc. London, 34: 243-247.

LOOSANOFF, W. R., 1937, Development of the primary gonad and sexual phase in Venus mercenaria L.
Biol. Bull., 72: 389-405.

LUCAS, A., 1965, Recherche sur la sexualité des Mollusques Bivalves. Bull. Biol. Fr. Belg., 99: 115-247.

LUCAS, A., 1966, Manifestation précoce de la sexualité chez quelques Mollusques bivalves. Lav. Soc.
Malacol. Ital., 3: 153-158.

LUCAS, A., 1968, Mise en évidence de l’hermaphrodisme juvénile de Venerupis decussata (L.) (Bivalvia,
Veneridae). С. К. Acad. Sc. Paris, tome 267, série D: 2332-2333 pl. 1.

MALACOLOGIA, 1969, 9(1): 277

PROC. THIRD EUROP. MALAC. CONGR.

CONTRIBUTION A L’ETUDE ECOLOGIQUE DES MOLLUSQUES
DES EAUX DOUCES ET SAUMATRES DE CAMARGUE!

Е. Marazanof
Laboratoire de Zoologie, Faculté des Sciences, Toulouse, France
RESUME

Parmi les 43 espéces mentionnées, la plupart sont caractéristiques des eaux douces ou faiblement oligo-
saumátres. Les espèces d’eaux saumätres sont réduites. Deux espèces marines: Cardium glaucum et
Abra ovata sont capables de s'adapter aux milieux mixohalins et hyperhalins.

11 espéces appartiennent aux Gastéropodes prosobranches, 20 aux pulmonés basommatophores, 12 aux
Lamellibranches.

A noter l’importance qualitative des espéces limniques, localisées dans les eaux homoiohalines ou faible-
ment oligohalines. Cette abondance serait liée, depuis l’extension de la riziculture en Camargue, a une
augmentation des biotopes d’eau douce.

Dans les eaux oligohalines et faiblement mésohalines cohabitent souvent des formes dulçaquicoles très
résistantes et des formes mieux adaptées aux variations plus importantes des salinités(Potamopyrgus
jenkinsi, Pseudamnicola anatina, Pseudamnicola compacta, Bithynia tentaculata, Physa acuta, Lymnaea
palustris, L. peregra, Ancylus fluviatilis).

Dans le domaine des eaux méso-poly et hyperhalines des étangs de moyenne et basse Camargue,
l’instabilite des facteurs physico-chimiques s’accentue, la salinité varie considérablement. Les alter-
nances d’inondations et d’asséchements, la faible profondeur des marais, déterminent un tri des espèces;
les Mollusques sténohalins sont éliminés au profit d’espéces eurythermes et euryhalines. On assiste a
une réduction du nombre des espéces et a une pullulation des individus de chaque езрёсе. Ne persistent
au maximum que 4 espèces: Cardium glaucum, Abra ovata, Hydrobia acuta, Hydrobia ventrosa.

Lorsque la salinité dépassait 60 470%/00, nous n'avons jamais rencontré de Mollusques dans les milieux
aquatiques du delta du Rhône.

lin extenso in: Annales de Limnologie, Toulouse, 1969 (in press).

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MALACOLOGIA, 1969, 9(1): 278

PROC. THIRD EUROP. MALAC. CONGR.
ZOOGEOGRAPHY OF HYDROBIID CAVE SNAILS
J. P. E. Morrison
U. S. National Museum, Smithsonian Institution, Washington, D. C., U.S.A.
ABSTRACT

Functional ducts of the male organs and opercular differences have been used since 1948 to clearly
separate the 4 subfamilies Hydrobiinae, Amnicolinae, Bythiniinae and Emmericiinae, of the small fresh-
water prosobranch snail family Hydrobiidae.

The Hydrobiinae possess only 1 functional duct (the vas deferens) in the verge. North American Hydro-
biine cave snails include only 1 species of Lartetia from a cave in Virginia, and 1 of Antroselates, a blind
relative of Lithoglyphus, from the Mammoth Cave region of Kentucky.

There are no members of the Amnicolinae (also called the Bythinellinae; with the vas deferens and a
“flagellum” structure in the verge) known to live in North American caves. Nor are any Bythiniinae (with
vas deferens and “flagellum,” and a calcareous operculum) recorded from caves in North America.

Fontigens and 4 other North American genera possess the triple-ducted male organ of Emmericia, and
so belong to the subfamily Emmericiinae. Fontigens and 1 other group with eyes are widespread in Appa-
lachian and Ozarkian springs. Some few of these Fontigens species now living in caves have greatly re-
duced eyes. At least 3 other generic groups known from the Appalachian and Ozark regions have been
living subterraneously so long they do not now show any eye structures whatsoever. In several North
American (Appalachian) caves, 2 species (1 blind and 1 not blind) are known to be living together, thus
indicating 2 waves of invasion into underground headwaters in 2 different geological eras.

The European genera such as Avenionia and Paladhilia, and the Japanese genera such as Akiyoshia,
Moria and Saganoa, cannot be correctly and finally placed in the appropriate subfamily until the gross male
anatomy of each of the pertinent type species is described and figured. In all cases type locality material
of the species and genus should be studied because similarities of such small shells, of so few different
shapes, may mask radically different anatomical features.

Until the hydrobiids from the Dalmatian and East Asiatic caves are classified to the correct subfamily,
the relict zoogeographic stories of these cave snails will remain seriously incomplete.

SELECTED BIBLIOGRAPHY

ALTENA, C. O. van Regteren, 1946, Faunistiche aanteekeningen I. Avenionia bourguignati (Locard) in
Nederland. Basteria, 10(3/4): 45-46.

HUBRICHT, L., 1940, The Ozark amnicolas. Nautilus, 53(4): 118-122.

HUBRICHT, L., 1963, New species of Hydrobiidae. Nautilus, 76(4): 138-140.

KURODA, T. & HABE, T., 1957, Troglobiontic aquatic snails from Japan. Venus, 19: 183-196, figs. 1-18.

MORRISON, J. P. E., 1949, The Cave Snails of Eastern North America. Amer. malac. Union, News Bull.
and annual Rep. for 1948: 13-15.

SIEBOLD, W., 1904, Anatomie von Vitrella quenstedtii (Wiedershein) Clessin. Jahresh. Verein. f. Vaterl.
Naturk. Württemberg, 60: 198-226; pls. 6 and 7.

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MALACOLOGIA, 1969, 9(1): 279-281
PROC. THIRD EUROP. MALAC. CONGR.
CYTOLOGICAL STUDIES OF INDIAN MOLLUSKS (ARCHAEOGASTROPODA: NERITIDAE)!
R. Natarajan

Centre of Advanced Study in Marine Biology, Marine Biological Station,
Porto Novo, Madras State, India

There is a scarcity of information on the chromosomes of Indian snails, and the few references available
come only from this laboratory (Seshaiya, 1938, Proc. silver Jub. Session Indian Sci. Congr., 3: 170; Jacob,
1954, Nature, 174: 1061-1062; 1957, Trans. roy. Soc. Edin., 63: 341- ; 1958, Ibid.,63: 433- ; 1959, J. zool.
Soc. India, 11(1): 17-25; 1959, Cytologia, 24: 487-497; Ramamoorthi, 1958, J. zool. Soc. India, 10(1): 33-38;
Natarajan, 1958, Curr. Sci., 27: 311-312; 1958, J. 2001. Soc. India, 10(2): 103-107; 1959, Ibid., 11: 30-33;
1960, Ibid., 12(1): 69-79). Patterson (1967, Malacologia, 5(2): 111-125), in a recent review, has indicated
a similar lack of information for nearly all the Streptoneura. The purpose of the present study of the
chromosomes of 10 neritid species from the Indian region is to document these chromosome numbers,
thereby increasing our knowledge of cytology of the Archaeogastropoda, and of its world-wide, highly
diverse family Neritidae.

The family Neritidae in India is represented chiefly by 3 genera: Nerita, Neritina and Septaria. Nerita
occurs mainly in the sea, Neritina lives in brackish waters, and Septaria is confined to freshwater. The
present account deals with the chromosomes of 4 species of Nerita and 1 species of Neritina from the
Andaman Islands, and 4 species of Neritina and 2 species of Septaria from peninsular India. Neritina
oualaniensis was studied from both places.

The results obtained are summarized in Table I. The chromosome numbers of Septaria tessellata is
2n = 22 + X in the male, and 2n = 22 + XX inthe female. The haploid number is п = 11 + X in both. The
caryotype of the male consists of one pair of large metacentric chromosomes with median centromeres,
one large metacentric element (X) with a submedian centromere, and 10 pairs of small metacentric
chromosomes with median centromeres. The female caryotype is similar but contains 2 large meta-
centric elements (2X) with submedian centromeres. Therefore, it is clear that the male is heterogametic.
The X-chromosome can be spotted easily during male meiosis because it occurs as a univalent. In other
neritid species in the present study, only male cells were studied. The chromosome number of each was
2n = 22 + X and/or n=11+X. The X-chromosomes of these species were always present as univalents,
and in each species this univalent had a submedianly placed centromere.

There are 3 previous reports of chromosome numbers of the Neritidae. Alexenko (1928, Z. Zellforsch.
mikroskop. Anat., 8: 80-124) reported Theodoxus fluviatilis to have 10 chromosomes during the first
division of meiosis, and 19 and 20 chromosomes in spermatogonial and odgonial cells respectively, with a
Х-0 sex-determining mechanism in males. Tuzet (1930, Arch. Zool. exp. gen., 70: 95-229) reported 9
chromosomes during meiosis and 18 in-spermatogonial cells of this same species, with a X-Y sex-deter-
mining mechanism in males. Nishikawa (1962, J. Shimonoseki College Fisheries, 11(3): 149-186) reported
п = 11, 2n =22inmales of Puperita (Heminerita) japonica, and could find no evidence for sex chromosomes.
Patterson (1967, Venus, Jap. J. Malacol., 25(2): 69-72) found Clithon retropictus to have 12 chromosomal
elements present during male meiosis, and Neritina (Dostia) violacea to have 14 elements. This latter
species has the highest chromosome numbers yet foundin the Neritacea. Both species studied by Patterson
had a heterochromatic bivalent which she suggested may be associated with sex determination.

There are a number of records of the occurrence of sex chromosomes in mollusks, but most of these
were published before 1931 and reported observations from techniques that would be considered inadequate
today (Patterson, 1967, Malacologia, 5(2): 111-125). More recent reports of sex chromosomes (all in the
Mesogastropoda) are those of Jacob (1959, Cytologia, 24(4): 487-497), Jacob (1959, J. 2001. Soc. India,
11(1): 17-25), Burch (1960, Amer. malacol. Union ann. Reps., 1959, 20: 15), Patterson (1963, Ibid., 30:
13-14) and Patterson (1965, Malacologia, 2(2): 259-265). The present report of a chromosomal sex-
determining mechanism in the Neritidae is the only recent record so far in the Archaeogastropoda. It
would be of considerable interest to know if sex chromosomes actually occur in other Archeogastropoda,
since the Neritacea are considered to be an annectant group bridging the morphological gap between the
archeogastropods and mesogastropods, and because it has been speculated that the ancestral mollusk was
hermaphroditic (Fretter & Graham, 1962, British prosobranch molluscs, Ray Soc., London, p 385).

l supported (in part) by research grant 7427 (SFC-07-0067) from the Smithsonian Institution, Washington,
DAC: AU. S.A.

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280 PROC. THIRD EUROP. MALAC. CONGR.

FIGURES 1 - 16. Chromosomes of Indian mollusks. FIG. 1. Septaria tessellata, female, 2n = 22+x+x,
oogonial late metaphase. FIG. 2. S. tessellata, male spermatogonial metaphase, 2n = 22+x. FIG. 3. S.
tessellata, female I metaphase, п = 11 + x. FIG. 4. $. tessellata, male I metaphase, п = 11 +х. FIG. 5.
S. compressa, male I metaphase, п = 11 +x. FIG. 6. Neritina retifera, male I metaphase, п = 11 +x.
FIG. 7. М. retifeva, male II metaphase, n= 11 апа п = 11 +х. FIG. 8. N. oualaniensis, male spermato-
gonial metaphase, 2n = 22 + x. FIG. 9. N. oualaniensis, male diakinesis, n=11+x. FIG. 10. Dostia
crepidularia, male diakinesis, п = 11 + x. FIG. 11. Nerita chamaeleon, male diakinesis, п = 11 + x.
FIG. 12. N. dombeyi, male spermatogonial metaphase, 2n = 22+x. FIG. 13. N. layardi, male diakinesis,
п = 11 +х. FIG. 14. М. plicata, male spermatogonial metaphase, 2n = 22+x. FIG. 15. N. rumphii, male

spermatogonial metaphase, 2n = 22 + x. FIG. 16. М. plicata, male diakinesis, n=11+x. Magnification
ca. 4100.

R. NATARAJAN 281

TABLE 1. Chromosome numbers in Indian Neritidae

Chromosome
number

Species Locality

Nerita
N. chamaeleon Linnaeus Andaman Islands

N. plicata Linnaeus Andaman Islands

N. dombeyi Récluz Andaman Islands

N. rumphii Récluz Andaman Islands

Neritina
N. oualaniensis Lesson o Andaman Islands
o
N. oualaniensis Lesson d' South India
fou
N. retifera Benson o South India
o
N. layardi Lesson om South India
N. (Dostia) crepidularia
Lamarck d' South India
o
Septaria

S. tessellata (Lamarck) South India

S. compressa (Benson) South India

MALACOLOGIA, 1969, 9(1): 282-283
PROC. THIRD EUROP. MALAC. CONGR.

DIE VERWANDTSCHAFTSBEZIEHUNGEN DER RHODOPE VERANII
KOLLIKER ZU DEN ONCIDIIDAE, VAGINULIDAE
UND RATHOUISIIDAE IN BEZUG AUF DAS NERVENSYSTEM

Edda Oberzeller
I. Zoologisches Institut der Universitit Wien, Wien, Austria
ZUSAMMENFASSUNG

Rhodope wurde 1847 von Kölliker entdeckt und als Nudibranchia beschrieben. Doch von jeher war ihre
systematische Stellung problematisch. Bereits 1854 beschrieb Schultze Rhodope als ein Turbellar mit dem
Namen Sidonia elegans. Schmidt (1858) und Diesing (1862) folgten der Annahme. Bronn (1866) reihte
sie unter die Opisthobranchia. Ihering (1877) will in ihr sogar eine Zwischenform von Turbellarien und
Mollusken sehen. Graff (1883) erkannte, dass Sidonia synonym zu Rhodope ist, stellt sie aber auch als
Zwischenform auf. Böhmig (1893) bringt die erste grosse Arbeit über den Feinbau heraus, stellt die Lage
der Körperöffnungen und eine äussere Anatomie des Nervensystems klar. Obwohl ihn die Vergleiche zu
den Gastropoda, sogar zu den Stylommatophora leiten, stellt er eine neue Klasse der Scolecida auf.
Thiele (1926) und Hoffmann (1931) reihen Rhodope hinter die Doridacea und Eolidiacea, und Boettger (1955)
schliesst sie mit einem gewissen Vorbehalt den Doridacea an. Erst die genaue Untersuchung der Ontogenie
von Rhodope durch Riedl (1960) zeigt, dassessich um einen “Pulmonaten” handelt. Die Furchung geht nach
dem Typus der Spiralier mit der Kreuzbildung, wie es für die Gastropoda charakteristisch ist. Die
Entwicklung ist eine direkte, es wird kein Larvenorgan voll ausgebildet und wieder reduziert. Es tritt
auch keine Veligerlarve auf.

Die Bildung des Nervensystems ist durchwegs eine ektodermale. Gleichzeitig mit der Bildung der Augen
entstehen die Cerebropleuralganglien in paarigen, weit voneinander entfernten Keimbezirken, wachsen
aber bald zusammen. Ein Sulcus deutet dann kurz die Trennung zwischen cerebralen und pleuralen Gang-
lien an. Die Ganglien rücken sehr eng aneinander, um den Oesophagus gruppiert. Kommissuren und Kon-
nektive treten durch die Bindegewebsmembran hindurch. Die Buccalganglien bilden nur einen Plexus, sie
zerfallen, sobald die Visceralkette abgeschlossen ist. Nach dem 12. Entwicklungstag sieht man nur mehr
einen Ganglienkomplex, nachdem die Bindegewebshüllen der einzelnen Ganglien zurückgetreten und die
Ganglien aneinandergerückt sind.

Das Wesentliche aber ist die Verlagerung des Subintestinalganglions und Abdominalganglions nach links.
Endgültig besteht die linke Oberschlundgruppe aus Cerebropleural- und Parietalganglien, die rechte aus
Cerebropleural-, Parietal- und Supraintestinalganglion. Die Unterschlundgruppe besteht aus Subintestinal-
und Abdominalganglion. Nur die Pedalganglien stellen kein Verschmelzungsprodukt dar.

Auch bei den sogenannten Pulmonata liegt ein einheitlicher Zug in der Verlagerung der Ganglien bei
Verkürzung der Visceralschlinge. Zu dieser Tendenz gehört das Einbeziehen der Parietalganglien mit den
Cerebropleuralganglien, die Verschmelzung von Subintestinal- und Abdominalganglien und die Verlagerung
nach links. Besonders bei den urtümlichen Stylommatophora lässt sich die Tendenz deutlich erkennen,
die ganz den Verhältnissen bei Rhodope entspricht.

Die amphibisch lebend, marinen Oncidiidae sind zwar ihrer äusserer Morphologie nach den Dorida-
cea sehr ähnlich, sie zeigen aber im inneren Bau viel mehr Übereinstimmung mit den primitiven Stylom-
matophoren. Das Nervensystem ist sehr konzentriert und zeigt ebenfalls eine deutliche Linksverlagerung
der Visceralganglien. Die landlebende Gruppe der Vaginulidae zeigt ebenfalls ein sehr konzentriertes
Nervensystem. Die Cerebralganglien sind unter denOesophagus gerückt, alle Kommissuren und Konnektive
sind bis zum Verschwinden verkürzt. Eine Trennung der einzelnen Ganglien ist kaum möglich. Auch die
Rathouisiidae mit dem Vertreter Atopos sind hierbei zu nennen. Es ist wohl das am meisten konzen-
trierte Nervensystem, von Kommissuren und Konnektiven ist nichts zu sehen.

Die sehr ähnlichen Verhältnisse der Konzentrierung, Verkürzung und Linksverlagerung der Visceral-
ganglien all dieser gezeigten Gruppen (Oncidiidae, Vaginulidae, Rathouisiidae und der Rhodope) weisen auf
eine enge Verwandtschaft hin. Sie sind nach dem euthyneuren System in die aus den Cephalaspidea sich
entwickelnden 5 о1ео lifera einzuordnen, die die einzige Ordnung der Euthyneura ist, die keinerlei
Gehäuse ausbildet. Nun zeigen die Untersuchungen des Zentralnervensystems eine deutliche Zusammen-
gehörigkeit dieser Gruppen. Denn wie all diese Gruppen weist auch Rhodope veranii in bezug auf das
Nervensystem eine hohe Zentralisierung, starke Verkürzung von Schlundring und Visceralschlinge bei
freien und nach links gerückten Visceralganglien auf.

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E. OBERZELLER

Vaginulidae Oe ee

Schemat. Darstellung d. Zentralnervensyst.

cg. -- Cerebralggl. parg. -- Parietalggl.
pedg. -- Pedalggl. spg. -- Supraintest. ggl.
plg. -- Pleuralggl. sbg. -- Subintest. ggl.

viscg. -- Visceralggl.

283

MALACOLOGIA, 1969, 9(1): 284

PROC. THIRD EUROP. MALAC. CONGR.

POPULATION CHARACTERISTICS OF VIVIPARUS ATER, CRISTOFORI AND JAN
(GASTROPODA, PROSOBRANCHIA) FROM TWO HABITATS OF LAGO MAGGIORE
(NORTHERN ITALY)

O. Ravera
Biology Directorate, Euratom Joint Research Center, Ispra, Italy
ABSTRACT

A study on two populations of Viviparus ater settled in two stations of Lago Maggiore was carried out
from 1962 to 1965 onseveralhundredof specimens. The two stations (Lavorascio and La Rotta) were small
bays ecologically very similar but rather distant one from the other, which consented an almost perfect
genetical isolation.

The material was collected by a sledge with a nylon net, but to measure the population density all the
specimens settled on a Square meter were collected by hand.

The population density decreased with depth and the highest concentration of young Molluscs and females
was found in very shallow water. The higher mean value was observed at 0.5 m depth (10.45 individuals/
sqm) and the lower one at 10 m (1 individual/sqm). The mean number of individuals per hectare was
50750 representing a biomass of 293 kg (wet weight); 117 kg due to the shells and 176 to the soft tissues.

For both stations the mean size of the females was greater than that of the males, but the bigger indi-
viduals were collected at La Rotta. About the individual growth for an increase of the height of the shell
of 1 cm, the wet weight of the soft tissues increased of about 3.3 grams for the male and female without
embryos, and 3.8 grams for the female with embryos; for the same increase of the shell height its wet
weight increased about 1 gram.

In both stations the fertility seems more strongly connected with the number of SOS per female than
with the sex-ratio. An increase of specific fertility with the size of the mother was observed, that is,
for the same population, with the age of the female. The percentage of females bearing embryos varied
with the station and the season, but throughout the year females with embryos were found.

To evaluate the metabolism of Viviparus its oxygen consumption was measured in the laboratory as well
as in the field. From the results obtained the following conclusions may be drawn: 1) at temperatures lower
than 15 C the metabolic rate was very low and the temperature coefficient (Q) was far lower than 2; 2)
at temperatures higher than 15 C the youngest animals had a Q equal to 3; this coefficient decreased with
increasing animal size until it became lower than 2 for the biggest Molluscs; 3) the difference in
oxygen uptake by individuals of different size increased with temperature. During the season at which the
population attained its highest metabolic and reproductive activity the oxygen uptake by the specimens
settled on an hectare was about 16 g/hr.

1This paper will be published “in extenso” in another journal.

MALACOLOGIA, 1969, 9(1): 284-285

PROC. THIRD EUROP. MALAC. CONGR.
OBSERVATIONS ON THE TENTACLES OF VAGINULUS BORELLIANUS COLOsIl
Aristeo Renzoni
Istituto di Zoologia, Universita di Siena, Siena, Italy
ABSTRACT

The author has conducted several experiments with the amputation of the tentacles of Vaginulus borellianus
(Gastropoda, Soleolifera) with the following purpose in mind:

a) to see whether regeneration occurs in this species and, if so, to analyse the phases and manner of
this process as well as the structure and ultrastructure of the regenerated organ;

b) to investigate the possible relationship betweenthe tentacle components (more precisely, their glandu-
lar and neuroglandular components) on one hand and the development of the gonads on the other.

The following results have been obtained:

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H. van der SCHALIE 285

1) The process of regeneration of amputated tentacles (optic and lower) in Vaginulus is substantially the
same as that described in the numerous studies of other pulmonates.

2) The weights of the body and ovotestis and the number of eggs in the ovotestis of experimental animals
show no significant variations either in comparison with each other or with the control animals.

3) Regarding both structure and ultrastructure, whereas the sensory cells in tentacles that have regen-
erated after a single amputation do not differ appreciably from the controls, those in tentacles that have
regenerated after repeated amputations of regenerative blastema are considerably altered, especially at
their apical end.

4) The eye consistently did not regenerate in any of the experimental animals (whether the tentacles
were cut off once or the blastema was cut off repeatedly).

lwill be published later in extenso in another publication.

MALACOLOGIA, 1969, 9(1): 285
PROC. THIRD EUROP. MALAC. CONGR.
AMERICAN MUSSEL RESOURCES IN RELATION TO THE JAPANESE PEARL INDUSTRY _
Henry van der Schalie
Museum of Zoology, University of Michigan, Ann Arbor, Michigan, U.S.A.
ABSTRACT

Harvesting of fresh-water mussels from streams in the Interior Basin of the United States has in recent
years assumed a position of importance equal to that reached at the turn of this century in the heyday of
the Pearl Button Industry. The new market created by the cultured pearl industry in Japan is extensive.
Exploitation of several rivers, such as the Tennessee, the Wabash and the Muskingum has become a matter
of concern both to malacologists and governmental agencies responsible for regulating and protecting that
resource.

Two surveys were conducted during the past several years aimed at obtaining a better understanding of
the effect of intensive commercial harvesting on the mussel fauna. One extended over a period of three
years in “Kentucky Lake,” an impoundment which the Tennessee Valley Authority created by means of a
dam in the lower Tennessee River at Paducah, Kentucky. The other - a current program - involves a more
normal river situation in the Muskingum River (a tributary to the Ohio) in Ohio. Both sites are interesting
in their own unique way: the one in Tennessee has impounded water piled up to a hundred feet in depth
above the mussel beds; the Muskingum is a less disturbed and more typical stream presenting a different
set of problems.

The study of the Muskingum is designed to determine: (1) the location of the beds in the lower 85 miles
of river; (2) population levels maintained by both the commercial and non-commercial species; and (3)
the effect of gear used in harvesting the mussels (among other factors). Hopefully, with this information it
will be possible to find methods for maintaining maximum yields for the expanding industry. Some assess-
ment of natural and human influences is necessary to protect the interests of all parties concerned.

MALACOLOGIA, 1969, 9(1): 286-287
PROC. THIRD EUROP. MALAC. CONGR.

SOME OBSERVATIONS ON THE LIFE-HISTORIES OF SOUTH INDIAN
FRESHWATER MUSSELS

R. V. Seshaiya

Centre of Advanced Study in Marine Biology, Marine Biological Station,
Porto Novo, Madras State, India

ABSTRACT

We have a wealth of information on the biology of European and North American freshwater mussels,
but we know little regarding the Indian species. The more common species occurring in South India are
Lamellidens marginalis (Lamarck), L.consobrinus (Lea), L.corrianus (Lea), Parreysia corrugata
(Müller), P. rugosa (Gmelin). Ihave made a more or less complete study of the development of Lamellidens
corrianus and the life-histories of all these species. The development of Lamellidens is very similar to
that of Anodonta, which was studied by Lillie (1895) and Herbers (1913). The present note reports the chief
features of the parasitic stage of the glochidium in the life-history of these mussels.

The mussels were periodically obtained from ponds and streams, and maintained alive in aquaria in the
laboratory for the collection of glochidia. Healthy glochidia were available chiefly during July and August
and again during December. The glochidia were transferred to petri dishes and small glass troughs for
effecting infection on suitable hosts. Glochidial infection was successfully carried out on a dozen species
of freshwater fish and also on the tadpoles of the frogs, Rana hexadactyla and Rhacophorus maculatus.
Among the fish, the murrel, Ophiocephalus was particularly well suited as a host for the glochidia, as it
could be easily handled, and as it could also stand heavy glochidial infection. Three species of the murrel,
Ophiocephalus punctatus, O. gachua and O. striatus are of common occurrence locally, and these were all
equally suitable hosts for the glochidia. Of the frog tadpoles, those of Rhachophorus have little pigmenta-
tion and proved suitable for glochidial infection. Heavily pigmented tadpoles, such as those of the toad
Bufo melanostictus were unsuitable, as the glochidia after encystment failed to metamorphose.

The glochidia of the mussels studied are of the hooked variety, i.e., with hooks on the glochidial shell,
and attach themselves to the fins of the host. After attachment on the fin, the encystment is completed
within half an hour by the growth of the surrounding tissue.

The noteworthy feature in the life-history is the very short duration of the parasitic or encysted stage,
i.e., the duration for metamorphosis of the glochidium. Glochidia collected in July and August meta-
morphosed in three days, whereas glochidia obtained in December took six to eight days to metamorphose.

According to Harms (1907), the time for metamorphosis of the glochidium of the European mussel
Anodonta cygnaea (L.) varies from 12 days to 80 days depending on temperature, as shown below:

Water temperature from 8 to 10°C 80 days
Water temperature from 16 to 18% C 22 days
Water temperature from 20°C 12 days

Lefevre and Curtis (1912) studied the duration of the parasitic stage of the glochidia of different mussel
species of North America, and found a general relationship between temperature and duration of the para-
sitic stage. For Symptonata the findings were as follows:

Temperature Duration of parasitic stage
16.09€ 14 - 16 days
16.39€ 15 - 18 days
173°C 11 - 14 days
178° C 9 - 13 days

Thus the glochidia of the South Indian mussels, it will be seen, metamorphose much more rapidly than
the European and North American species. During the warm months with a temperature of 29° to 30°C in
the medium, the metamorphosis took only three days. Inthe cold season with a temperature of about
24° to 25°, the metamorphosis took 6 to 8 days.

The speeding up of the organogenesis isalsointeresting. During the warm months the encysted glochidia
show all the definitive structures of the juvenile mussel.

In the case of the glochidia encysted on the fins of tadpoles, the repair of the breached fin-tissue, after
the metamorphosed glochidium drops down, is very rapid and the movement of cells to bridge the gap can

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R. V. SESHAIYA 287

be observed under the microscope.

The abbreviation of the life-history is an adaptation to environmental conditions and is also observed
in several other tropical organisms. For example the frogs, Cacopus systoma and Rhacophorus maculatus,
often breed in shallow pools of rainwater during the warm months, and metamorphosis is much shortened
as compared to that in the cold months.

Another feature of interest is with regard to the number of successive glochidial infections which a fish
could stand. It was observed that a single specimen of Ophiocephalus could successfully serve as a host
for six or seven infections. But further infections were unsuccessful and the glochidia dropped off without
metamorphosis.

An attempt was made to determine the approximate time taken by the juvenile mussel to attain maturity
by collection of shells of various sized groups, and observing the lines of growth on the shell and noting
the periods of retardation of growth. From the observations made so far, it is inferred that the juvenile
mussel takes about two years to attain maturity. In the European mussel sexual maturity is not attained
till the fifth year.

REFERENCES

LILLIE, F. R., 1895, The Embryology of the Unionidae. Journ. Morph. 10: S. 1-100.

HARMS, W., 1907, Uber die postembryonale Entwicklung von Anodonta piscinalis. Zool. Anz. 31:S.
801-814, 7 Abb.

LEFEVRE, G. U. & CURTIS, W. C., 1912, Studies on the Reproduction and Artificial Propagation of
Freshwater Mussels. Bull. Bur. Fish. Washington, 30: (Document Nr. 756) S. 105-201. Taf. 6-17,
4 Abb.

HERBERS, K., 1913, Entwicklungsgeschichte von Anodonta cellensis Schröt. Zeitschr. f. wiss. Zool., 108,
S. 1-174, 104 Abb.

MALACOLOGIA, 1969, 9(1): 288
PROC. THIRD EUROP. MALAC. CONGR.
LEBENSFORMEN FOSSILER BIVALVIA
Rudolf Sieber
Wien, Austria
ZUSAMMENFASSUNG

Unter den fossilen Bivalvia ist eine grosse Zahl kennzeichnender Lebensformen zu beobachten. Sie
stimmen entweder mit solchen rezenter Muscheln überein oder stellen mehr oder weniger eigene Typen
dar. Bei der Ermittlung der letzteren müssen nicht bloss biologische Merkmale, wie etwa einseitige
morphologische Spezialisation, Vergesellschaftung, Bewuchs u.ä., verwendet werden, sondern auch geolo-
gische, wie etwa Vorkommen in Lebensstellung und faziologisches Auftreten sowie paläogeographische und
regional-tektonische Verbreitung. Dadurch lassen sich fast alle fossilen Bivalvia hinsichtlich ihrer
Lebensformen und Lebensweisen erfassen. Nur einige können noch nicht befriedigend gedeutet werden, so
rostroconchide Conocardien, bei welchen es noch einer eingehenderen paläoökologischen Analyse bedarf.

Von den Lebensformen, die mit solchen rezenter Muscheln weitgehend übereinstimmen, seien beispiels-
weise grabende und bohrende Vertreter von Solen, Pinna und Lithophaga angeführt, die schon im Palä-
ozoikum durch verwandte oder konvergente Typen verfolgbar sind, wie Palaeosolen und “Sulcatopinna.”
Ferner sind zu nennen Kugel- oder globose Formen des Bewegtwassers, wie Linga columbella, Cardita
partschi und Glycymeris pilosa; halbkugelförmig gewölbte Formen finden sich bei Pecten, Gryphaea u.a.
Mytiliform sind neben Mytiliden Myoconcha. Auch Linsen- und Scheibentypen des Flachwassers kommen
vor (Codokia; Placuna, Carolia).

Die als überwiegend fossil zu bezeichnenden Lebensformen treten etwa bei einzelnen Arten der hier in
einem 2.Т. weiterem systematischen Sinne gebrauchten Gattungen Trigonia, Megalodus, Congeria, Hip-
purites, Eumorphotis, Inoceramus und Diceras auf. Sie sind als benthonisch zu betrachten und bildeten
Angehörige der Epi- und Endofauna. Als nicht benthonische, aber bewegte Formen dürfen Posidonia,
Monotis und Daonella angesehen werden.

Trigonien gehörten überwiegend dem Seichtwasserbereich an. Ihrer grossen Area und ihrer starken
Skulptur kann unter Hinweis auf die Lebensweise des rezenten Corculum cardissa die funktionelle Bedeutung
der Einebnung und Verankerung in das Bodensediment zugesprochen werden. Ähnliche Verhältnisse liegen
bei Myophoria und Roudairea vor; auch einige Arten der paläozoischen Gattung Grammysia (С. undata u.
G. nodocostata) und Mecynodon (M. carinatus) weisen ingleiche Richtung. Die meist im dem Riffkern nahen
Kalkschlick vorkommenden Megalodontidae stellen wenig tief eingegrabene Triasmuscheln dar. Der Hip-
puriten-Typus ist ein nicht litoraler Seichtwasservertreter und scheint ausser bei den Rudisten auch bei
Spondylidae (Sp. olsenae u.a. Arten) auf. Liegeformen des wenig weichen Bodens weisen Congeria (C.
subglobosa), Lima (L. lineata) und die devonische Congeriomorpha auf, welche eine vordere Liegefläche
und eine schwache Byssusfestheftung gehabt haben. Bei den flach mützenförmigen Bivalven, wie Eumor-
photis aurita, E. tellevi, Claraia clarai, Anomia patelliformis und wohl auch der der rezenten Enigmonia
aenigmatica sehr ähnlichen paläozoischen Hercynella bohemica, die durch Byssus oder Cicatrix fest-
geheftet waren, handelt es sich um Formen der mehr oder weniger bewegten Flachsee. Unter den Inocera-
men sind meist Seichtseeformen zu finden; nur der radialgerippte Inoceramus sulcatus des Albien und die
gryphaeaartige Art J. involutus deuten auf stärkeres Bewegtwasser hin. Charakteristische Rollformen des
Bewegtwassers kommen neben Lucinidae (Linga) bei Diceraten vor, deren mit stark eingerollten Wirbel-
teilen versehene Vertreter die Hänge der Tithonriffe besiedelten. Eine nicht benthonische Lebensweise
meist des tieferen Stillwassers ist aus Fossilisation, Bauform und Vergesellschaftung für die meist
dünnschaligen Posidonien, Daonellen und Monotidae zu erschliessen.

Bei den verschiedenen Lebensformen lassen sich zahlreiche kennzeichnende Spezialisationsmerkmale
feststellen, in welchen meist eine möglichst funktionsgerechte Ausbildung der Typen zum Ausdruck kommt,
wobei einzelne fossile Fälle besonders aufschlussreich erscheinen. So tritt Schalenabplattung in lateraler
oder antero-posteriorer Richtung auf, ferner Kugel- und Kelchbildung. Die Flügel- und Ohrenbildung, etwa
der Pectinidae, ermöglicht eine sichere Klappenbewegung; die gegenihren Schlossrand stark abgewinkelten
Schalen bei Bakevelliidae (Gervillia) u.a. gewährleisten eine nicht zu grosse und vor allem gleich weite
Öffnung der Klappen. Abgeflachte hintere Schalenteile bewirken eine Abschwächung mechanischer Ein-
wirkung bei starker Wasserbewegung (Trigonia, Grammysia, Mecynodon).

Zu zahlreichen Lebensformen fossiler Bivalvia können konvergente Beispiele anderer Schalentiere;
besonders der Brachiopoda, aufgezählt werden. So entsprechen Mucrospirifer reidfordi und einzelne
Productacea in Form und Lebensstellung Tridacnidae; Meekella und Richthofenia sind Hippuritentypen.
Darin kommt hiemit eine allgemeinere biologische Gestaltung zum Ausdruck.

Die stratigraphische Uebersicht der Lebensformen fossiler Bivalvia weist auf charakteristische und
unterscheidende Eigenschaften erdgeschichtlicher Formationen hin.

Die hier verwendete Literatur wird in einer eigenen der Paläoökologie der fossilen Bivalvia gewidmeten
Uebersichtsdarstellung angeführt.

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MALACOLOGIA, 1969, 9(1): 289
PROC. THIRD EUROP. MALAC. CONGR.
PHYLOGENETIC POSITION OF THE SUCCINEIDAE
Alan Solem
Field Museum of Natural History, Chicago, Illinois, U.S.A.
ABSTRACT

Traditionally the Succineidae have been considered to be primitive Stylommatophora, either ancestral
to the more advanced Sigmurethra or a side branch of pulmonate evolution. Recent suggestions that they
are opisthobranchs or a distinct, primitive order were thought to be bolstered by the discovery of low
chromosome counts in various Catinellinae.

Studies on aulacopod sigmurethrans with reduced visceral humps and dissection of several succineids
suggest a revision of their phylogenetic position. Rather than being primitive land snails occupying a habi-
tat transitional between water and land, the succineidsare a phylogenetically advanced group that has made
a partial reversion to a near aquatic habitat. They are secondarily derived from the arionid-limacoid
group in the Sigmurethra and thus much more advanced than the Orthurethra or Mesurethra. Previously
cited “primitive” features in the Succineidae can be shown to be either secondary modifications correlated
with the reduction in visceral hump and altered shell form, or consistent with alternative explanations.

The transverse kidney and pallial configuration in the Succineidae is duplicated in the endodontoid sub-
family Charopinae, since shortening and broadening of the kidney is one method of compensating for pallial
cavity compression. Possession of a closed and complete secondary ureter is phylogenetically much more
important and indicates that the Succineidae is advanced, rather than primitive. Features in the repro-
ductive system of the Succineidae cited by Rigby and Quick as differentiating them from the most advanced
Helicidae and Zonitidae are duplicated in the more generalized aulacopod lines. For example, a bifurcated
talon is characteristic of the Discinae; completely separated prostate and uterine oviducal tubes are in the
Endodontinae and many other taxa; and the trend to separation of the penial region into penis proper and
epiphallus is duplicated in several arionid subfamilies.

Odhner’s suggestion that the subfamily Catinellinae is a natural assemblage occupying a more primitive
position is not supported by dissections. Catinella, Quickella and Mediappendix appear to be relatively
advanced genera that are independently derived from “Succinea” -type ancestors. Their low chromosome
numbers can be interpreted as resulting from a drastic reduction series. These genera inhabit marginal,
temporary, pioneer habitats where it is advantageous for a species to build up a population quickly with
minimal variation. Reduction in chromosome numbers lowers the possibility of variation. Under these
circumstances, a reduction series produces a selective advantage.

Morphological structures of the Succineidae are consistent with their being considered as slightly ab-
errant members of the more generalized aulacopod Sigmurethra and thus they are among the phylogeneti-
cally more advanced land snails; the subfamily Catinellinae is polyphyletic and its genera derived from the
Succineinae; and low chromosome numbers in the Catinellinae probably result from aneuploid changes.

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MALACOLOGIA, 1969, 9(1): 290
PROC. THIRD EUROP. MALAC. CONGR.
GROWTH STUDIES ON OLIVELLA BIPLICATA (SOWERBY, 1825)!
R. Stohler

Department of Zoology, University of California
Berkeley, California, U. S. A.

ABSTRACT

Based on field observations it was assumed that Olivella biplicata had a life span of possibly 3 or 4
years. To ascertain the actual life spanunder natural conditions (as contrasted to laboratory experiments)
a method of marking shells without causing interference with the natural life processes of the animals was
devised; groups of marked animals were then released in a particularly favorable spot where the species
occurs naturally yet is, at the same time, kept from emigrating. This makes periodic recapture of the
marked animals possible; after re-measuring they are released in the same place.

Early results indicated that the life span is considerably longer than was assumed; estimates of from 8
to 15 years appear now more than reasonable. Growth spurts have been observed, but in general annual
increments seem to vary between 1 and 3 millimeters.

lin extenso in Veliger, vol. 11, р 259-267.

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MALACOLOGIA, 1969, 9(1): 291-292

PROC. THIRD EUROP. MALAC. CONGR.

THE INFLUENCE OF CLIMATE ON THE ADULT SIZE OF RECENT AND FOSSIL
HIATELLA ARCTICA (LINNE) AND ITS IMPORTANCE FOR DETERMINATION
OF PALAEOTEMPERATURE

F. Strauch
Geological Institute, University of Cologne, West Germany
ABSTRACT

Hiatella arctica (Linne) has had a world wide distribution from the early Tertiary through to the present.
Study of recent Hiatella has shown that features such as numerical distribution, shell form, and growth are
temperature-controlled. Studies on fossil Hiatella reveal a similar pattern. In particular:

1. Numbers of H. arctica individuals in given faunalassemblages increase polewards, in both absolute
and comparative terms as the number of other lamellibranchs present decrease.
This feature results both from the direct influence of temperature on a species thriving best in
arctic conditions and from the indirect influence of temperature in decreasing the number of species
in competition with Hiatella in the same zone.

2. Adult shell size varies in length between 6 and 45 mm, the larger being found near the poles, the
smaller near the equator.
This result appears even more closely controlled by temperature than the preceding case, although
the lack of competition in the Arctic no doubt plays an important role in encouraging unrestricted
growth.

3. The rugosa-type developed by boreal and arctic Hiatella is not a function of environmental adap-
tation but of the average of absolute size.

By using the results based on feature 2 above, it has proved possible to demonstrate an analogous tem-
perature related control of adult shell size for fossil populations of Hiatella arctica. Measurements on
accurately placed and dated fossil populations show a clear increase in shell size between Eocene and late
Glacial times.

This size/age relationship can be used to derive quantitative temperature data from size measurements
of adult fossil populations. Temperature curves representing yearly temperature minima and maxima for
different Hiatella shell lengths were derived from a series of recent samples reaching from the tropics to
the Arctic. These curves were superimposed withthe shell length of fossil Hzatella populations. Minimum
and maximum temperature values as well as the mean can be read from the graph directly:

M. Europe: winter - summer yearly average temperature
M. Eocene 26,0% to 28,0% С 21086
O. Oligocene 20,5% to 27,0% С 23,50 €
Miocene ca. 17,0° to 27,0° C 22 00€
Pliocene 13,5° to 22,00€ 17,59 C
Waltonian 12,00 to 21,0° C 16,5% С
Newbournian 8,0% to 19,0% С 13,5°C
Butleyan 5,0010 17,5° € 02°C
Eem-Interglacial ca. 10,0° to 20,0° C 15,0°C
Late Würm 310° ю 11,0° € 5,00 С
(Recent, Dogger Bank 6,0° to 16.0° € 11,096)

These values can clearly only be taken as working approximations, for one has but to consider the varia-
tions present in such a narrowly defined area as the present day North Sea to realise the almost certainly
equal complexity of its forerunners. Nevertheless, the method allows a significant advance to be made on
the hitherto published temperature data for the marine Cenozoic. This is particularly true of the area of
Middle and Northwest Europe from which the bulk of the measurements was made.

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292 PROC. THIRD EUROP. MALAC. CONGR.
LITERATURE CITED

STRAUCH, F., 1968, Determination of cenozoic sea-temperatures using Hiatella arctica (LINNE).
Palaeogeogr., Palaeoclimat., Palaeoecolog., 5: 213-233.

FIG. 1. Average length of adult specimens of recent Hiatella arctica of different localities in relation
to temperature internals. (STRAUCH 1958). 1 = Barbados, 2 = Hawaii, 3 = Algiers, 4 = Pisa, 5 = Naples,
6 = Zadar, 7 = St. Barbara, Calif., 8 = S. Bretagne, 9 = Dogger Bank, North Sea, 10 = Oslo Fjord, 11 =

Varanger Fjord, 12 = Tjörnes, N. Iceland, 13 = Hardanger Fjord, 14 = Lofoten, 15 = Unalaska Is., 16 =
Spitsbergen, 17 = Jan Mayen, 18 = Bering Is., 19 = East Greenland).

0 10 20 30 40mm 50

FIG. 2. Standards of temperature curves with fossil data of Hiatella arctica indicated. (Only samples of
the southern Cenozoic North Sea were used: 1-3 = Oligocene, 4-9 = Miocene, 10-14, Pliocene, 15-21 =
Early Pleistocene, 22 = Eem, 23-26 = Late Würm.) (STRAUCH 1968)

MALACOLOGIA, 1969, 9(1): 293-294
PROC. THIRD EUROP. MALAC. CONGR.

ELABORATION DE LA MATIERE OPERCULAIRE CHEZ TRICOLIA PULLUS (L.),
GASTROPODA, PROSOBRANCHIA

Jean Vovelle

Laboratoires d’Anatomie comparée et de Cytologie de la Faculté
des Sciences de Paris, et Station biologique de Roscoff, France

RESUME

Des recherches antérieures, non intégralement publiées, portent sur quelques Prosobranchia (Gibbula
magus, That's lapillus, Viviparus viviparus), et nous assurent que l’opercule de ces espèces est une lame
homogene de protéine durcie par “tannage quinonique,” excluant la participation de toute trace de chitine,
méme a l'état de trame que la matiére sclérifiée imprégnerait. Chez Tricolia pullus, calcification et
durcissement de matiére protéique coexistent: les deux disques, calcaire et organique, qui peuvent se
dissocier chez les Turbinidae pris au sens large, matérialisent topographiquement cette superposition.
Les seules études voisines de notre propos concernent Turbo ou Astralium, abordés d’une facon descrip-
tive; grace a HOUSSAY, SAHM, KESSEL, HUBENDICK, on connait le róle d'un bourrelet operculaire in-
dépendant du bourrelet palléal, a l’origine des zones de croissance de l’opercule, a propos duquel KESSEL
a judicieusement corrigé les vues de HOUSSAY en situant а sa face inférieure la composante organique
qu’il interpréte comme “conchine” et non plus comme “revétement chitineux.”

Nous avons précisé par des voies surtout histochimiques, a partir d’une étude d’anatomie microscopique
détaillée, non seulement la nature des divers composants de l’opercule complexe de Tricolia, mais aussi
la situation et l’apparence cytologique des tissus sécréteurs correspondants. Cet opercule oligogyre spiral
apparaît comme un ménisque blanc, elliptique, marqué d’une spire interne en relief. Il est serti par le
repli operculaire, enveloppe tégumentaire pigmentée, en croissant lobulé sur les cótés qui, sur le vivant,
le recouvre aux deux-tiers et se révele indépendant du bourrelet palléal postérieur dont la fixation le
rapproche. Toute décalcification découvre une lame organique inférieure discréte, ambrée, adhérant au
disque operculaire par une zone en fer a cheval élargie aux extrémités et complétée caudalement par un
repli plissoté.

Sur coupes sagittales de la région pédieuse, on situe les tissus intéressants a partir du repère d'une
“souttiére operculaire.” Cette incision est délimitée cránialement par le repli operculaire, dont l’arête
lobée présente de hautes cellules sécrétoires. Aurebord caudal, l’opercule organique succéde immédiate-
ment А un sillon qui s’extroverse a son contact sur le vivant, grace а un systeme d’éléments vacuolaires
qui permet a des cellules glandulaires d'assurer la croissance de la spire organique. Celle-ci, méme sans
présenter la “lamelle hyaline” réfléchie caractéristique de Gibbula ou Thats, prend donc a l’origine un
aspect cuticulaire. Suit un épithélium cubique а tonofibrilles qui représente la zone d’adhérence du disque
operculigére a la musculature sous-jacente. Dans le deuxiéme tiers de la surface du disque, l’opercule
repose sur le repli plissoté riche en mucocytes. Histologie et observation sur le vivant imposent de
rechercher dans les catégories cellulaires antérieures du repli et de la gouttiére les éléments sécréteurs
de l’opercule.

On a pratiqué les tests histochimiques en gardant l’opercule en place. Sa fraction minérale est assez
fragile pour être solubilisée non seulement par les fixateurs picriqués, mais aussi par les fixateurs bi-
chromatés postchromés; elle disparaít en tous cas par traitement au Complexon. La fraction organique
de l’opercule révele alors trois strates:

- Une lame interne, d’épaisseur constante, correspondant seule a une scléroprotéine tannée. Rouge a
l’Azan, réfractaire aux tests de Mucopolysaccharides, elle s’affirme comme une protéine a radicaux
aromatiques par des tests signalétiques (Vert Malachite), ou spécifiques des groupements réducteurs (R.
argentaffine) ou des polyphénols (R. chromaffine), la Dopa-réaction donnant a son niveau une condensation
mélanique.

- Une pellicule intermédiaire “adhésive” mucopolysaccharidique. Bleue a l’Azan, réagissant au Bleu
Alcian et, métachromatiquement, au Bleu de Toluidine, elle comporte surtout des mucopolysaccharides
acides, méme si 1’А.Р.5. suggére une discréte composante “mucoide.”

- Une matrice organique calcaffine topographiquement indépendante. Ses réponses aux tests des muco-
polysaccharides, son affinité pour les laques nucléaires (notamment 1'Hémalun viré par une solution
picriquée) en proposent la nature mucoprotidique.

A la stratification de l’opercule correspondent, depuis le repli operculaire jusqu’au rebord caudal de la
gouttiére, des bandes de cellules sécrétoires différentes:

- Les sécrétions a l’origine de la protéine “tannée” ont été révélées notamment par le réaction argen-
taffine pour les radicaux aromatiques, et par la Dopa-réaction pour le phénolase associée. Située juste a
la limite inférieure du sillon, une mince bande de cellules a sécrétion apicale argentaffine poussiéreuse

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294 PROC. THIRD EUROP. MALAC. CONGR.

doit jouer le röle principal, mais les cellules hautes a cytoplasme basophile qui précédent juste la zone
d’adhérence peuvent aussi intervenir, de méme que les cryptes glandulaires de la paroi opposée de la
gouttiére, dont on connaît l’homologue chez That's ou Gibbula.

- L'epithélium du fond de la gouttiére présente des cellules caliciformes riches en mucopolysaccharides
acides qui les impliquent dans l’&laboration de la pellicule intermédiaire.

- La créte du repli operculaire définit un lobe sécrétoire dont les hautes cellules sont soit vacuolaires
soit chargées de granules. Signalée par une légère coloration vitale à 1'Alizarine, la détection du calcaire
а leur niveau a été pratiquée par les méthodes aux métaux lourds. La méthode de Lillie, variante “in toto”
du Kossa avec décalcification simultanée, est apparue plus positive encore que celle de Stoelzner au
niveau des sécrétions granuleuses. La sécrétion mucoprotidique doit être associée a l’élément minéral.
Pour confirmer ces images d’élaboration calcique (quasi inconnues au niveau de l’épithélium palléal des
Mollusques), on a recouru à un procédé indirect. Le rôle intermédiaire des phosphatases alcalines est
suffisamment établi à propos de la coquille pour qu’on puisse les considérer comme des indicateurs
valables: on les a détectées par diverses techniques, dont celle de Pearse qui écarte toute ambiguïté et
qui révèle l’enzyme sur un liseré apical de la région intéressée exclusivement.

En conclusion, histologie et histochimie concourent pour rattacher à des tissus sécrétoires différents
et éloignés les divers éléments constitutifs de l’opercule composite de Tricolia. Il est facile de recon-
naître dans le disque organique inférieur une lame homogène de protéine durcie par tannage quinonique,
qui en fait l’homologue de l’opercule tout entier, tel qu’il apparaît chez les autres Prosobranchia déjà
étudiés. Isolé par la couche intermédiaire “adhésive” de mucopolysaccharides, le disque calcaire super-
ficiel tient aussi son indépendance de son lieu d’élaboration, et sa matrice calcaffine mucoprotidique est
différente des deux strates organiques auxquelles elle se superpose sand transition. On pourrait évoquer
à son propos, en disposition inversée, les situations respectives de la coquille calcaire et du periostracum
(dont divers travaux portant sur les Lamellibranchiata indiquent qu’il s’agit d’une protéine tannée), n’était la
frontière très tranchée qui individualise les composants “organique” et “minéral” de l’opercule de Tricolia.

BIBLIOGRAPHIE

HOUSSAY, F., 1884, Recherches sur l’opercule et les glandes du pied des Gastéropodes. Arch. Zool. exp.
gen., 2: 271-288.

HUBENDICK, B., 1948, Über den Bau und das Wachstum des konzentrischen Operculartypus bei Gastro-
poden. Ark. for Zoologi, 40: 1-28.

KESSEL, E., 1942, Über Bau und Bildung des Prosobranchier-Deckels. Z. Morph. u. Ökol. Tiere, 38:
197-250.

SAHM, W. (in FLEISCHMANN, A.), 1932, Vergleichende Betrachtungen über das Schalenwachstum der
Weichtiere. Z. Morph. u. Ökol. Tiere, 25: 555-590.

VOVELLE, J., 1967, Sur l’opercule de Gibbula magus (L.), Gasteropode Prosobranche: édification,
nature protéique et durcissement par tanhage quinonique. С. R. Acad. Sc., Paris, 264: 141-144.

MALACOLOGIA, 1969, 9(1): 295-296

PROC. THIRD EUROP. MALAC. CONGR.

ANATOMISCHE UNTERSUCHUNGEN DES ZENTRALNERVENSYSTEMS VON
FIMBRIA FIMBRIA UND MELIBE LEONINA

Christa Waidhofer
I. Zoologisches Institut der Universität Wien, Austria
ZUSAMMENFASSUNG

Die Opisthobranchia Fimbria finbria und Melibe leonina sind Arten der Familie Tethymelibidae, die den
Aeolidiaceae zugeordnet ist. Das Zentralnervensystem dieser beiden Formen, besonders von Fimbria
fimbria, istinder Literatur oft erwähnt, aber noch nie genau untersucht worden. Die spärlichen Abbildungen
sind unexakt und zum Teil auch falsch.

Die Opisthobranchia weisen in ihren verschiedenen Organen bestimmte Entwicklungstendenzen auf. Die
Hauptlinie dieser Evolution reicht von einer asymmetrischen Körperform mit Schale und nicht konzen-
triertem Nervensystem zu einer symmetrischen Form, die schalenlos und durch eine Konzentration der
Ganglien charakterisiert ist. Von Ihering 1922 hat eine dieser Theorie entgegengesetzte Ansicht gedussert.
Für ihn gilt das konzentrierte Nervensystem gewisser Nudibranchia, z.B. Fimbria fimbria, als “Proto-
ganglienmasse” und somit als ursprünglicher Ausgangspunkt, während sich die Formen mit getrennten
Ganglien sekundär davon ableiten sollen. Hanström 1929 hat darauf hingewiesen, dass die Konzentration
des diffusen Nervensystems in ein zentrales und die Verschmelzung von ursprünglich getrennten Ganglien
zu höheren, fest vereinten Einheiten einen iin ganzen Tierreich gemeinsamen Prozess darstelle, und dass
Iherings Theorie dazu in schroffem Gegensatz stehe und abgelehnt werden müsse.

Nach den neueren Untersuchungen charakterisiert Wirz 1952 den Entwicklungsprozess zur Konzentration
des Nervensystems durch drei Vorgänge, die aber nicht immer gekoppelt sein müssen.

1. Cephalisation: so wird der Vorgang der Ganglienwanderung zum Vorderpol genannt.

2. Cerebralisation: unter diesem Prozess versteht man die Verschmelzung der nach vorne gewanderten
Ganglien. Die Verschmelzung erfolgt nach ganz bestimmten Regeln. Das Nervensystem wird dadurch zu
einer zentralisierten Bildung, einem “Gehirn.”

3. Telencephalisation: dieser Vorgang besteht zunächst in der Bildung von Spezialzellen in den höchsten
Zentren, den Cerebralganglien, dann in deren Zunahme an Masse, und schliesslich werden Funktionen,
deren Sitz sich bei den ursprünglichen Formen in den rückwärtigen Ganglien befindet, in die Cerebral-
ganglien verlagert. Diese Bildung von Integrationszentren wird Telencephalisation genannt.

Das Zentralnervensystem von Fimbria fimbria (Abb. 1), das in eine kompakte, milchig- durchsichtige
Bindegewebshülle eingeschlossen ist, weist eine sehr starke Konzentration an der Schlundoberseite auf.
Bei oberflächlicher Untersuchung scheinen sich alle Hauptganglien in eine einzige elliptische Masse zu
vereinigen. Entfernt man die Bindegewebshülle, so kann man deutlich die einzelnen Ganglienzellen sehen,
die bis 1 mm Durchmesser erreichenkönnen. Diese extrem grossen Nervenzellen treten nur in bestimmten
Regionen des cerebralen, pleuralen und pedalen Bereiches auf und sind mehr oder weniger stark gestielt.
Sie bilden dadurch ein ganz lockeres Gefüge, wodurch die Gangliengrenzen verwischt werden. Hebt man
die Ganglienzellen mit einer Pinzette ab, so wird die Form des zentralen Nervenfaseranteils sichtbar.
Die Cerebral- und Pleuralmassen sind miteinander verschmolzen, die Pedalganglien sind aber dem Cerebro-
pleuralkomplex nur genähert. Die getrennten Cerebropedal- und Pleuropedalkonnektive sind deutlich zu
erkennen. Auf der rechten Ventralseite des Zentralnervensystems (Abb. 2) ist das Abdominalganglion
deutlich sichtbar, und es ist nicht mit dem Pleuralkomplex verschmolzen, sondern diesem nur angelagert.
Es hat spindelförmige Gestalt und ist in seiner Grösse reduziert. Beim durchscheinenden Licht sind am
Faserkomplex deutlich dunkle und helle Stellen zuunterscheiden. In den dunklen Regionen sind die Nerven-
fasern besonders dicht gelagert und sie stellen die Ganglienzentren dar, während zwischen diesen die
Nervenfasern wesentlich seichter verlaufen. Von einer Verschmelzung der Hauptganglien zu einer ein-
heitlichen Masse kann man eigentlich nicht sprechen. An der Ventralseite des Zentralnervensystems kann
man im Gegensatz zur Dorsalseite auch schon nach der Zellgrösse die Ganglienregionen feststellen.
Riesenzellen treten hier nicht auf. Seitlich amSchlund (Abb. 3) liegen die Buccalganglien, die aus wenigen,
verschieden grossen Zellen bestehen.

Beim Zentralnervensystem von Melibe leonina sind die Hauptganglien ohne nähere Untersuchung schon
deutlich zu unterscheiden. Alle Ganglien bzw. Ganglienkomplexe haben eine unregelmässige und asym-
metrische Form. Besonders der cerebrale Anteil ist stark zerklüftet. Die Nervenzellen der Ganglien
(Abb. 4) sind in ihrer Grösse nicht so extrem verschieden wie bei Fimbria fimbria. Sie sind nicht gestielt
und dem Faseranteil locker aufsitzend, sondern durch eine enge Bindegewebshülle zu einer festen Form
zusammengepackt. Auch an der Ventralseite ist die Zerklüftung der Ganglien deutlich sichtbar. Die
Cerebropedal- und Pleuropedalkonnektive (Abb. 5) bilden im Gegensatz zu Fimbria fimbria einen einheit-
lichen Strang. Die Buccalganglien sind bei Melibe leonina von kugeliger Gestalt und bestehen aus zahl-

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296 PROC. THIRD EUROP. MALAC. CONGR.

reichen Nervenzellen.
Zwischen dem Zentralnervensystem von Fimbria fimbria und Melibe leonina gibt es zahlreiche mor-

phologische Unterschiede, die jedoch im Hinblick auf ihre systematische Stellung nicht von Bedeutung sein
diirften, da die beiden Arten in Bau und Funktion der tibrigen Organsysteme und in ihrer Lebensweise
übereinstimmen. Wieweit histologische Unterschiede im Zentralnervensystem vorhanden sind, wird noch

zu untersuchen sein.

BIBLIOGRAPHIE

IHERING, H. von, 1922, Phylogenie und System der Mollusken. Arch. Moll. 1: Heft 1.
HANSTROM, B., 1929, Zur vergleichenden Anatomie des Zentralnervensystems der Opisthobranchier.

7. f. Morph. u. Ökol. Tiere 16. Bd 1; 2. Heft.
WIRZ, K., 1952, Remarques sur l’évolution du système nerveux des Opisthobranches. Arch. zool. exp.

gen. 88: Notes et Revue 161-177.

MALACOLOGIA, 1969, 9(1): 297-299
PROC. THIRD EUROP. MALAC. CONGR.
RECENT ADVANCES IN LAND MOLLUSC RESEARCH IN SWEDEN
Henrik W. Waldén
Natural History Museum, Göteborg, Sweden
ABSTRACT

An extensive, faunistic-ecological survey of the land molluscs (and some further terrestrial groups) in
central and southern Sweden, is being carried out by the Góteborg Natural History Museum. It was started
in 1921 by the late Dr. Hans Lohmander. The survey was presented by the present author at the First
Europ. Malac. Congress, 1962. Since that time the survey has advanced considerably, and a brief report
about the most important advances is justified.

Concerning the scope, principles and methods reference shouldbe made to the Congress Report (Waldén,
1965). Fig. 1 shows how far the survey has advanced up to 1968. The black areas are surveyed in detail,
from the dotted areas only scattered literature or museum records exist, and the white areas are entirely
unknown. Besides the coherently surveyed area in southern and central Sweden, certain river valleys in
northern Sweden have been investigated, in connection with their exploitation for hydroelectricity, which
makes it necessary to collect documentary evidence of the destroyed areas for the future.

Since 1962 more than 2,600 collecting sites have been investigated, of which about 2,250 are situated in
southern Sweden and more than 350 in the northern river valleys. In all more than 18,000 localities have
been investigated in Sweden since the survey started. Parallel with the field work, the large amount of
material left behind by Dr. Lohmander is being gradually worked out.

Besides the Swedish survey the Museum carries out surveys of a more extensive character in neigh-
bouring countries. Thus a revision of the Norwegian collections of land molluscs has been undertaken and
supplementary work has started, in cooperation with the Zoological Museums in Norway. Already the
present work has rather profoundly modified the picture of distribution of the species of Carychium,
Succinea, Columella, Cochlicopa, Vitrea, Nesovitrea and Euconulus, of certain species of Vertigo, Vallonia,
Arion and Deroceras, and of Acanthinula aculeata. Two species, viz. Clausilia dubia and pumila, should
evidently be eliminated from the list of Norwegian species, whereas others should be added, as Vertigo
genesii and geyeri, Limax valentianus and Zonitoides arboreus. Obviously the results from Norway are of
great importance when the conditions in Sweden are interpreted.

In connection with his survey in southern Sweden Dr. Lohmander did extensive collecting work in Den-
mark during 1930-39 and 1954-58. In all he investigated some 1,500 localities. Owing to the decease of
Dr. Lohmander this survey also was not finished by him. However, an agreement has been made to under-
take supplementary collecting work in cooperation with the Aarhus Natural History Museum in Denmark,
so the remaining gaps in the survey will be covered.

TAXONOMIC REVISION

The genera Nesovitrea and Columella have been revised. Inthe genus Nesovitrea (Waldén, 1966b) the
specific distinction between hammonis (Ström) and petronella (L. Pfeiffer) has been definitely proved. The
nearctic species, electrina (Gould) and binneyana (Morse), are clearly distinguished from the European
species, without any intermediates.

In the genus Columella a new species, С. aspera Waldén (1966a, р 53) has been recognized. It is defi-
nitely clear that C. columella (Martens) also is a distinct species. The survey has also made clear that
the nearctic so-called C. edentula, described as C. simplex by Gould, is remarkably distinct both from the
European edentula (Drap.) and aspera. It may possibly be a distinct species, but this needs further work
to be proved. On the other hand С. alticola (Ingersoll) without any doubt is conspecific with С. columella.

Until now very little has been published about C. aspera, but it appears to be the prevalent species of
the genus in NW Europe. Fig. 2 shows its distribution in the province of Halland in SW Sweden. It is
almost ubiquitous here, being particularly prevalent in oligotrophic areas. C. edentula (Fig. 3) proved
to be rare and local, mainly confined to luxuriant woods and fens, especially on calcareous soil.

For a number of further aggregate groups conclusive evidence has been obtained that they are composed
of distinct species, though the results have not yet been published. These are Vertigo arctica and ron-
nebyensis (the relation to the nearctic У. modesta is disregarded in the present connection), У. genes?
and geyeri, Arion circumscriptus, silvaticus and fasciatus. In addition to this the relation between
Deroceras laeve and sturanyi, which Simroth and his followers considered to represent stages of a sex-
change cycle, has been definitively disentangled.

On the other hand, the complex of Cochlicopa species must still be regarded as far from solution.

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298

PROC. THIRD EUROP. MALAC. CONGR.

Columel la aspera

Columella edentula
Distribution in

Distribution in
Hal land Halland

Vertigo arctice

cra 180 records

Vertigo genesii
30 records,

2 A ce
a \ {$
Pe, q a

Columella columella

с:а 40 records

> ses р 9
PSA A EA

à 1 as . 4

Lr rene 15)

H. W. WALDEN 299
FAUNISTIC RESULTS

Some examples of a wider zoogeographical interest will be considered. The three species regarded
below are of particular interest, because they were characteristic of the coldest phases of the Pleistocene
in central Europe and in the British Isles. Today they are, outside Scandinavia, limited to the highest
alpine areas of Europe.

The subfossil Mollusca are included in the survey. When the distribution is considered both recent and
fossil evidence are included. Subfossil records from localities, where the species are now extinct, have
been indicated on the maps by crosses.

Vertigo arctica (Wallenberg) (Fig. 4). This species has proved to be regularly distributed along the high
mountain ridge, and on lower levels in northernmost Scandinavia. Besides, it has a seemingly isolated
occurrence in the mountain gorge Skáralid in southernmost Sweden. У. arctica appeared very early after
the ice age. Later it seemstohave become extinct, except in the mountains and at Skáralid. Evidence from
several sites indicate that it must have survived the Post Glacial Warm Period (Atlanticum) here. The
recent occurrence in the south is reasonably regarded as relict.

Vertigo genesii Gredler (Fig. 5) also occurs over a large stretch in the Scandinavian mountains, though
it is decidedly rarer than V. arctica. In southern Sweden it still lives in cold spring bogs on the calcareous
mountains of Västergötland. Fossil evidence is known from this area, from Jämtland in northern Sweden
and from southernmost Sweden. In the last area it is now extinct. The recent distribution is quite con-
sistent with the fossil history. The occurrence in Västergötland has a clearly relict character.

Columella columella (Martens) (Fig. 6) has a similar distribution to У. genesi¿, though it is decidedly
more northern. It occurs on low levels in northernmost Scandinavia. It is evidently absent in southern
Sweden. There it is known only fromthe oldest strata, and disappears when the Warm Period begins.

Above it has been pointed out that the typical alpine and Glacial Period species V. arctica and genesii
were able to survive the Post Glacial Warm optimum in southernmost Sweden. The mollusc fauna here
of this period has a remarkably heterogeneous character. On the one hand it comprises typical central
European species, such as Laciniaria biplicata, Iphigena ventricosa and Monachoides incarnatus, which are
today much rarer. Together with those species (though, of course, in different habitats) there lived the
above mentioned alpine species and, in addition, the boreal species Nesovitrea petronella and Discus
ruderatus, which are today decidedly much rarer in this part of Sweden.

The co-occurrence of these very different faunal groups stands in contrast to the hitherto known botanical
evidence. Reasonably it must modify the conception of the climate during the Post Glacial Warm Period.

REFERENCES

WALDEN, H. W., 1965, Terrestrial faunistic studies in Sweden. Proc. First Маас. Congress, 95-109.

WALDEN, H. W., 1966a, Einige Bemerkungen zum Ergänzungsband zu EHRMANN’s “Mollusca” in “Die
Tierwelt Mitteleuropas.” Arch. Moll:, 95: 49-68.

WALDEN, Н. W., 1966b, Zur Frage der Taxionomie, Nomenklatur und Okologie von Nesovitrea hammonis
(Stróm) und petronella (L. Pfeiffer). Ibid., 95: 161-195.

pra fee zed o |
a TEE be ve

MALACOLOGIA, 1969, 9(1): 301-302
PROC. THIRD EUROP. MALAC. CONGR.

SYSTEMATICS OF THE GENUS POTAMOPYRGUS (HYDROBIIDAE) IN EUROPE,
AND THE CAUSATION OF THE KEEL IN THIS SNAIL

T. Warwick
Department of Zoology, University of Edinburgh, U. K.
ABSTRACT

The snail Potamopyrgus jenkinsi (Smith), was first described as Hydrobia jenkinsi by Smith (1889),
from Thames estuary specimens. Thiele (1928)transferredthe snail to the genus Potamopyrgus. Warwick
(1952) reported differences between material collected at localities well inland and that found in brackish
waters near the coast. These coastal specimens were identical with early Thames estuary specimens in
the British Museum (Natural History). They are therefore considered to be P. jenkinsi sensu stricto.
The shell whorls are convex with a marked suture. The whorls increase rapidly in size growing a stout
shell and the mantle is deeply pigmented. There is a dense patch of pigment near the eye. P. jenkinsi s.s.
is usually limited in Western Europe to brackish water and freshwaters of the coastal zone. Rarely it has
been found in inland localities. The species ranges from Finland to the Mediterranean coast of France.
Though somewhat slender and stout forms both occur there is little variation in shell shape and the species
is not polymorphic. An ornamented variety (var. carinata) with a keeled shell occurs. Populations with
well marked keels are rare. Usually all specimens in a population are smooth or the keel is present only
as a line in a low proportion. P. jenkinsi s.s. bears a distinct resemblance in shell shape to species of
this genus found in southeastern Australia, Tasmania and New Zealand. However, it differs from these
Australasian snails in various characters.

The Potamopyrgus found in inland localities belongs to a type provisionally called Strain A, Warwick
(1952). This has a very distinctive shell and pigmentation of the soft parts. The shell is slenderer and
more elongate than in P. jenkinsi s.s. The suture is shallower and the whorls are distinctly less convex,
being somewhat flat. In clean shelled specimens the mantle colcuration is seen to be much paler. This
is true too of the pigment patch near the eye. The remarks about ornamentation in P. jenkinsi s.s. apply
also to Strain A. This strain is the commonest and most widespread form of Potamopyrgus in Europe. It
is found in coastal waters even if they are strongly brackish (19% seawater). Usually it is the only form
found well inland in Europe. In 1950 specimens of Potamopyrgus from coastal streams in Wales were
collected, their shells had the black deposit usual in this genus. When bred in the laboratory the pig-
mentation was studied through the clean shell. Though like P. jenkinsi 3.5. there was a black pigment
patch near the eye in other respects pigmentation was different. The ground colour of the mantle seen
through the body wall is pale. Ithas, however, numerous irregular patches of darker pigment. Shell shape
is much as in P. jenkinsi s.s. with slender and stout forms occurring. This strain has been provisionally
called “C”, Warwick (1952). Strain C differs from strain A and P. jenkinsi s.s. in the facility with which
it grows a keel. The keel is often well developed as tufts of spines. This strain is common on the Welsh
and Irish coasts. In England it occurs in Kent and East Anglia and inland in Derbyshire. On the Continent
it has been found at two localities near Biarritz, France. The type of distribution is like that of P. jenkinsi
s.s. It is proposed elsewhere to re-describe P. jenkinsi s.s. and to describe strains A & C as species of
the genus Potamopyrgus. It is appreciated that the splitting up of somewhat similar populations of com-
pletely parthenogenetic animals presents taxonomic problems. How such a matter should be treated must,
according to Mayr (1963), be decided for each case. There seems to be valid grounds in this case. Here
we have 3 forms showing differences in shell shape, pigmentation, ornamentation and distribution. Todd
(1964) showed that at least one physiological difference occurs as well. Two and more rarely three of
these strains may sometimes occur side by side. When they do so strain A can be separated by shell
shape and pigmentation. It is more difficult to separate P. jenkinsi s.s. and Strain C as their shell shape
is similar. However, well-keeled specimens may belong to C and this strain often has nearly colourless
tentacles. If clean shelled material is available, the patchy mantle pigmentation of C is diagnostic.

The causation of the keel has attracted interest and attention. Robson (1925) bred keeled snails but
obtained only smooth offspring. Boycott (1929), breeding aculeate snails, obtained a low percentage of
keeled forms. Boettger (1949) also produced some keeled snails in the laboratory. The conditions under
which these keeled snails occurred were inconclusive. The above work suggests that the keel is partly
due to environmental characters. Warwick (1952) suggestedthat keel formation was partly genetical, partly
environmental. It has been substantiated that different populations have different threshold values for keel
formation. However, Warwick’s suggestion that algal metabolites are responsible for keel formation has
not been confirmed by later work. Since 1952, work has been continued on this problem, and reproducible
results have been obtained. Strong keels have been grown from smooth parents of P. jenkinsi and strain A.
These experiments will be fully described elsewhere. The keel develops in the presence of an adequate

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302 PROC, THIRD EUROP. MALAC. CONGR.

quantity of humic materials in the water or food. In nature, amongst other sources of such material, one
may mention dead leaves of deciduous trees and dead stems and leaves of sedges (Carex spp.).

REFERENCES

BOETTGER, C. R., 1949, Hinweise zur Frage der Kielbildung auf der Schale der Wasserschnecke Pota-
mopyrgus crystallinus jenkinsi (Е. A. Smith). Arch. Moll., 77: 63-72.

BOYCOTT, A. C., 1929, The inheritance of ornamentation in var. aculeata of Hydrobia jenkinsi Smith.
Proc. malac. Soc. Lond., 18: 230-234.

MAYR, E., 1963, Animal Species and Evolution. Oxford Univ. Press, London, 797 p.

ROBSON, G. C., 1926, Parthenogenesis inthe mollusc Paludestrina jenkinsi. Part II - The Genetical
Behaviour Distribution, etc., of the Keeled Form (“var. carinata”). J. exp. Biol., 3: 149-160.

SMITH, E. A., 1889, Notes on British Hydrobiae, with description of a supposed new species. J. Conch.,
Lond., 6: 142-145.

THIELE, J., 1928, Revision des Systems der Hydrobiiden und Melaniiden. Zool. Jahrb. Jena. Syst., 55:
351-402.

TODD, М. E., 1964, Osmotic balance in Hydrobia ulvae, and Potamopyrgus jenkinsi (Gastropoda: Hydro-
biidae). J. Exp. Biol., 41: 665-677.

WARWICK, T., 1952, Strains in the mollusc Potamopyrgus jenkinsi (Smith). Nature, Lond., 169: 551-552.

MALACOLOGIA, 1969, 9(1): 303-305
PROC. THIRD EUROP. MALAC. CONGR.
DIE ULTRASTRUKTUR DER SOHLENDRUSENZELLEN VON ARION RUFUS L.
Günter Wondrak

Elektronenmikroskopisches Laboratorium der
Tierärztlichen Hochschule in Wien, Austria*

ZUSAMMENFASSUNG

Die Sohlendrtisenzelle ist gekennzeichnet durch einen Drilsenbauch und einen mehr oder weniger von
diesem abgesetzten, gewundenen Drüsenhals. Im apikalen Bereich ist sie durch eine Zonula adhaerens,
eine Zwischenzone und eine Zonula septata (WONDRAK, 1968) mit den Epithelzellen verbunden. Die freie
Oberfläche des Drüsenhalses ist eingebuchtet und an ihrem Rand stehen Mikrovilli, die bei Extrusion des
Sekretes verschwinden. Im Hals findet man, neben Zwischen- und Endprodukten der Schleimsynthese,
Mitochondrien und Ausläufer des Ergastoplasmas.

Im Drüsenbauch fällt vor allem das hochorganisierte Ergastoplasma auf (WONDRAK, 1967; Abb. 4, 7),
dessen Membranabstand, ausgenommen an den Verzweigungsstellen, sehr konstant ist (ca. 0,15 - 0,2 u).
Ins Innere ragen kleinste, senkrecht zu den Membranen stehende Tubuli von са. 0,02 и Durchmesser (Abb.
2, 3). Wo der perinukleäre Spalt erweitert ist, beinhaltet er die gleichen Tubuli (Abb. 1). Die gleiche
Differenzierung des Ergastoplasmas weisen die Zymozyten der Speicheldrüse von Helix aspersa (QUAT-
TRINI, 1967), die “metachromatic cell” von Helicella obvia(RÖHLICH & BIERBAUER, 1966), welche sicher
eine Sohlendrüsenzelle darstellt, sowie die Pedaldrüsenzellen von Arion rufus und die Sohlendrüsenzellen
von Helix pomatia (WONDRAK, 1969) auf. Die Mitochondrien stehen mit dem Ergastoplasma in engem
Kontakt. Der Golgi-Apparat zeigt je nach Funktionsstadium verschieden weite Bläschen mit unterschied-
lich elektronendichtem Inhalt. An den Zellbauch treten vegetative Nervenendigungen heran (Abb. 5).

An manchen Zellen sieht man stark zerklüftete Drüsenbäuche, die von der Oberfläche Bläschen ein-
schnüren, welche man immer extrazisternal zwischen den Membranen des Ergastoplasmas beobachtet,
das sich hier bis in die Spitzen der Vorwölbungen erstreckt. Während der verschiedenen Stadien der
Sekretsynthese, soweit sie als solche elektronenoptisch erkennbar sind, konnten keine strukturellen Ver-
änderungen des Ergastoplasmas beobachtet werden. Der Golgi-Apparat zeigt in seinen Vesikeln häufig
elektronendichtes Material (Abb. 6). An anderen Stellen erscheint sein Inhalt “herausgelöst” und seine
Lamellen sehr stark erweitert (Abb. 4). Im Zytoplasma liegen membranbegrenzte, elektronendichte,
schwammartig strukturierte Granula von ca. 0,5 - 0,8 y Durchmesser. Sie scheinen aus häufig zu sehen-
den, weniger elektronendichten und nicht membranbegrenzten Gebilden von unregelmässiger Gestalt zu
entstehen. An anderen Stellen liegen extrazisternal sehr grosse Vakuolen, die von stark erweiterten
Golgi-Membransystemen stammen und deren Inhalt “herausgelöst” erscheint (Abb. 4). Die dunklen Granula
findet man bis in den apikalen Teil des Drüsenhalses, doch konnte niemals ihre Extrusion beobachtet
werden. Auch trägt die freie Oberfläche in diesem Stadium immer Mikrovilli. Dagegen sieht man oft
Zellen, die ihren homogenen, wenig dichten Inhalt durch den weit offenen Drüsenhals abgeben.

LITERATURVERZEICHNIS

QUATTRINI, D., 1967, Osservazioni sulla ultrastruttura dei dotti escretori delle ghiandole salivari di
.. Helix aspersa Müller (Mollusca, gastropoda, pulmonata). Caryologia, 20: 191-206.

ROHLICH, P. & BIERBAUER, J., 1966, Electron microscopic observation on the special cells of the optic
tentacle of Helicella obvia (Pulmonata). Acta Biol. Hung., 17: 359-373.

WONDRAK, G., 1967, Die exoepithelialenSchleimdrüsenzellen von Arion empiricorum(Fér.). Z. Zellforsch.
76: 287-294.

WONDRAK, G., 1968, Elektronenoptische Untersuchungen der Körperdecke von Arion rufus L. (Pulmonata).
Protoplasma, 66: 151-171.

WONDRAK, 1969, Elektronenoptische Untersuchungen der Drüsen- und Pigmentzellen aus der Körper-
decke von Arion rufus L. (Pulmonata). Z. mikr. anat. Forsch. 80: 17-40.

*Derzeit: Institut f. Biochemie d. Universitat Wien, Austria.

(303)

304 PROC. THIRD EUROP. MALAC. CONGR.

АВВ. 1. Perinukleärer Spalt. Fixierung: Glutaraldehyd. Kontrastierung: Bleizitrat. Vergrösserung:
48000: 1.

ABB. 2. Querschnitt durch Tubuli des Ergastoplasmas. Fixierung: Glutaraldehyd - Osmiumsäure.
Kontrastierung: Phosphorwolframsäure. Vergrösserung: 88000: 1.

ABB. 3. Längsschnitt durch Tubuli des Ergastoplasmas. Fixierung: Glutaraldehyd - Osmiumsäure.
Kontrastierung: Phosphorwolframsäure. Vergrösserung: 88000: 1.

ABB. 4. Drüsenbauch. Fixierung: Glutaraldehyd. Kontrastierung: Bleizitrat. Vergrösserung: 20800: 1.

ABB. 5. Synapse. Fixierung: Glutaraldehyd. Kontrastierung: Bleizitrat. Vergrösserung: 128000: 1.

ABB. 6. Golgi-Zone. Fixierung: Glutaraldehyd - Osmiumsäure. Kontrastierung: Bleizitrat. Ver-
grüsserung: 19200: 1.

ABB. 7. Schema des Ergastoplasmas.

C, Kollagenfibrillen; ER, Ergastoplasma; GZ, Golgi-Zone; M, Mitochondrium; N, Zellkern; Ne, Nerv;
Nu, Nukleolus; R, Ribosomen; S, Sekretgranulum; SV, Sekretvakuole; T, Tubuli; —>weist auf erwei-
terten perinukleären Spalt mit tubulären Innenstrukturen. Alle Schnitte stammen von in Epon eingebettetem
Material.

G. WONDRAK 305

LIST OF CONGRESS MEMBERS

*ADEGOKE, O. S., Dept. of Geology, University of Ife, Ibadan, Nigeria.
ALVAREZ, J., Dep. di Zool., Istit. Esp. de Entomol., J. Gutierrez Abascol 2,
Madrid, Spain.
ANDERSON, R. C., University Guelph, Guelph, Ontario, Canada.
ANGELETTI, 5., 20, via Pascarella, Milano, Italy.
ANT, H., Wielandstr. 17, Hamm D-47 Westf., West Germany.
*APLEY, M. L., LMS 1-34, Woods Hole Oceanographic Institution, Woods Hole,
Massachusetts 02543, U.S.A.
AX, R., Friedrich Eberstr. 21, D-75 Karlsruhe, West Germany.
AZEVEDO, J. Fraga de, National School of Public Health and Tropical Medicine,
R. da Junqueira 96, Lisboa, Portugal.
BACHMAYER, F., Geol.-Paleont. Dept., Museum of Natural History, Burgring 7,
A-1010, Vienna, Austria.
BACKHUYS, W., Maredijk 75, Leiden, The Netherlands.
BARASH, A., Tel-Aviv University, Dept. of Zoology, 155 Herzl Str., Tel-Aviv,
Israel.
BARBER, L., c/o UNDP, Box 1505, Colombo, Ceylon.
BAUMANN, B., 721 Lechner Lane, Pittsburgh, Pennsylvania 15227, U.S.A.
BEBBINGTON, A., Bristol University, 13, Red House Lane, Westbury-on-Trym,
Bristol, England.
BERRIE, A. D., Dept. of Zoology, The University of Reading, Reading, England.
BINDER, E. E., Muséum d’Histoire Naturelle, B. P. 284, Genéve, Switzerland.
BOETERS, H., Rumfordstr. 42, D-8, Munich 5, West Germany.
BOETTGER, С. R., Güldenstr. 40 В, D-33, Braunschweig, West Germany.
BOLLING, W., Luitpoldstr. 33, D-86, Bamberg, West Germany.
BOSS, K. J., Dept. of Mollusks, Museum of Comparative Zoology, Harvard University,
Cambridge, Massachusetts, U.S.A.
BOUSFIELD, E. L., National Museum of Canada, Ottawa, Ontario, Canada.
BRANDHORST, A. L., Stationsplein 56, Den Haag, The Netherlands.
*BRANDT, R., G.P.O. Box 2696, Bangkok, Thailand.
BROEK, E. van den, Institut f. Vet. Parasitologie, Yalelaan-de Uithof. Utrecht,
The Netherlands.
BRUGGEN, A. C. van, Rijksmuseum v. Natuurlijke Historie, Raamsteeg 2, Leiden,
The Netherlands.
*BRUNSON, R. B., Dept. of Zoology, University of Montana, Missoula, Montana 59801,

U.S.A.
BURCH, J. B., Museum of Zoology, The University of Michigan, Ann Arbor, Michigan
48104, U.S.A.

BUTOT, Г. J., Burg у. Heemstrakwartier 120, De Bilt, The Netherlands.

CHATFIELD, J., Dept. of Zoology, The University of Reading, Reading, England.

*CHESLER, Е. R., 1225 NE 17th Way, Ft. Lauderdale, Florida, U.S.A.

CHETAIL, M., Faculté des Sciences- Anatomie comparée, 7 quai St. Bernard,
Paris VE, France.

CHEVALLIER, H., Laboratoire de Malacologie, Muséum d’Histoire Naturelle,
55 rue de Buffon, Paris V®, France.

CLARKE, A. H., National Museum of Canada, Natural History Branch, Ottawa,
Ontario, Canada.

*CLERX, J. P., State University, Dr. de Bruynestraat 5, Leiderdorp, The Netherlands.

COOMANS, H. E., Zoologisch Museum, Plantage Middenlaan 53, Amsterdam, The
Netherlands.

*in absentia
(307)

308

CRAWFORD, G. I., Stantons Hall Farm, Blindley Heath, Lingfield, Surrey, England.
DANCE, S. P., National Museum of Wales, Cardiff, Wales, U.K.
*DEMIAN, E. S., Dept. of Tropical Public Health, Harvard University, Boston,
Massachusetts 02115, U.S.A.
DRIEST, J. Ph. van, Hoogegeest 37, Akersloot, The Netherlands.
DUNDEE, D. S., Louisiana State University, Lakefront, New Orleans, Louisiana,
U.S.A.
EALES, N. B., Littledown, Kingswood, Henley-on-Thames, Oxon., England.
EEDEN, J. A. van, Snail Research Group of the C.S.I.R., Potchefstroom University
for C.H.E., Potchefstroom, South Africa.
ELSER, H., Elisabethstr. 17, A-4600 Wels, Austria.
ETGES, F. J., Dept. of Biol. Sciences, University of Cincinnati, Cincinnati, Ohio
45221, U.S.A.
EYERDAM, W. J., 7531 -19th Avenue N. E., Seattle, Washington, U.S.A.
FALKNER, G., Konrad Peutingerstr. 4, D-8 Munich, 25, West Germany.
*FEEN, W.S. van der, Villa “De Wael,” Domburgseweg 6, Domburg, The Netherlands.
FOGAN, M., 181, New Brook Road, Atherton, Manchester, England.
FORCART, L., Zürcherstr. 9, CH-4000, Basel, Switzerland.
FOULQUIER, L., Commissariat a l’Energie Atomique, Section de Radioécologie,
13, St. Paul-lez-Durance, CEN-Cadarache, France.
FOURNIE, J., Lab. d’Anatomie et Histologie comparées, Faculté des Sciénces,
7 quai St. Bernard, Paris VS, France.
FRANCHINI, C. A., 37, via Cremona, I-46100 Mantova, Italy.
GAILLARD, J. M., Lab. de Malacologie, Museum National d’Histoire Naturelle,
55 rue de Buffon, Paris V*, France.
GARAVELLI, С. L., Ist. di Mineralogie, Palazzo Ateneo, I-70100, Bari, Italy.
GHISOTTI, F., via Giotto 9, Milano, Italy.
GIROD, A., via Savona 94/A, Milano, Italy.
GISMANN, A., 19 Road 12, Maadi, Egypt, U.A.R.
GITTENBERGER, E., Rijksmuseum van Natuurlijke Historie, Raamsteeg 2, Leiden,
The Netherlands.
GIUSTI, F., Istituto di Zoologia, via Mattioli 4, Siena, Italy.
GORDON, H. S., Chemical Engineering Magazine, McGraw-Hill Publishing, 24th
floor, 330 West 42nd Street, New York 10036, New York, U.S.A.
GROSSU, A. V., Facultatea de St. Naturale, Splaiul Independentei 93, Bucuresti,
Roumania.
GRUNBERG, F., Freyung 6, A-1010, Vienna, Austria.
HADL, G., I. Zool. Inst. d. Universität, Dr. Karl Luegerring 1, A-1010, Vienna,
Austria.
HADZISCE, S., Hidrobioloski zavad, Ohrid, Yugoslavia.
HAEFELFINGER, HR., Naturhistorisches Museum, Augustinergasse 2, CH-4000
Basel, Switzerland.
HEPPEL, D., Royal Scottish Museum, Chambers Street, Edinburgh, Scotland, U.K.
HOHORST, W., Loreleystr. 109, D-623 Frankfurt/M.- Unterliederbach, West
Germany.
HORST, D. von der, Wittelsbachstr. 80, D-67 Ludwigshafen/Rh., West Germany.
HUBENDICK, B., Naturhistoriska Museet, Góteborg 11, Sweden.
HURST, A., Dept. of Zoology, The University of Reading, Reading, England.
IMHOF, G., II. Zool. Institut а. Universität, Dr. Karl Luegerring 1, A-1010, Vienna,
Austria.
JANUS, H., Staatliches Museum f. Naturkunde, Schloss Rosenstein, D-7, Stuttgart 1,
West Germany.

309

JONES, J. LLEWELLYN, Honan, West Mersea, Essex, England.
JONES, R. LLEWELLYN, Honan, West Mersea, Essex, England.
JOOSSE, J., Zool. Dept., Free University, Boelelaan 1087, Amsterdam, The
Netherlands.
KEARNEY, A., The Agricultural Institute, Creagh, Ballinrobe, Ca. Mayo, Eire.
*KIAUTA, B., Genetisch Instituut, Opaalweg 20, Utrecht, The Netherlands.
KLEEMANN, K., Wipplingerstr. 24, A-1010, Vienna, Austria.
KLEMM, W., Mollardgasse 12 b, A-1010, Vienna, Austria.
*KLINKEY-BARR, M., 336 Main Str., Batavia, Illinois 60510, U.S.A.
KNIPPER, H., Landessammlungen f. Naturkunde, P.O. Box 4045, D-75, Karlsruhe,
West Germany.
KNUDSEN, J., Universitetets Zoologiske Museum, Universitetsparken 15, Köbenhavn
@, Denmark.
KOLLMANN, H., Geol.-Paläontol. Dept., Museum of Natural History, Burgring 7,
A-1010, Vienna, Austria.
KOTHBAUER, H., I. Zool. Inst. а. Universität, Dr. Karl Luegerring 1, A-1010,
Vienna, Austria.
KRAEMER, L. R., Dept. of Zoology, University of Arkansas, Fayetteville, Arkansas,
U.S.A.
*KRAUSE, J. A., Alpha Gamma Ro, University of Connecticut, Storrs, Connecticut,
US. A:
KROLOPP, E., Magyar Allami Földtani Intezet, XIV., Nepstadion u. 14, Budapest,
Hungary.
KUHNELT, W., II. Zool. Inst. d. Universität, Dr. Karl Luegerring 1, A-1010, Vienna,
Austria.
KUIPER, J. G., 121 Rue de Lille, Paris УП®, France.
LAMMENS, J., Free University, Boelelaan 1087, Amsterdam, The Netherlands.
*LARAMBERGUE, M. de, Laboratoire de Zoologie, Universite de Poitiers, Poitiers,
France.
LARYEA, A. A., Dept. of Zoology, University College of North Wales, Bangor,
Wales, U.K.
LEMCHE, H., Universitetets Zoologisk Museum, Universitetsparken 15, Kpbenhavn,
ф, Denmark.
LLOYD, D. C., Dept. of Zoology, University College of North Wales, Bangor,
Wales, U.K.
LUCAS, A., Faculté des Sciénces, Avenue le Gorgeu, Brest 29 N, France.
MacCLINTOCK, C., Peabody Museum of Natural History, Yale University, New
Haven, Connecticut 06520, U.S.A.
MARAZANOF, F., Laboratoire de Zoologie, 118, Route de Narbonne, Toulouse,
France.
*McMILLAN-FISHER, N., The Nook, Uplands Road, Bromborough, Chesh., England.
MEAD, А. R., University of Arizona, Tucson, Arizona, U.S.A.
MEIER-BROOK, C., Tropenmedizinisches Institut, Wilhelmstr. 11, D-54 Tubingen,
West Germany.
MEULEMAN, E. A., Zool. Dept., Free University, Boelelaan 1087, Amsterdam,
The Netherlands.
MEYER, T., Herman Robberstraat 9 Ш., Amsterdam, The Netherlands.
MIKULA, E., Kaiserstr. 8/36, A-1070, Vienna, Austria.

310

MILLER, W. B., Dept. of Biological Sciences, University of Arizona, Tucson,
Arizona, U.S.A.

MOENS, R., Station d’Entolomogie, Gembloux, Belgium.

MORPHY, M. J., Veterinary Research Laboratories, Stormont, Belfast, N.-Ireland,

UK,

MORRISON, J. P., Division of Mollusks, U.S. National Museum, Washington, D.C.
20560, U.S.A.

MUCSI, M., Szegedi Jozse Attila Tudomanyegyetem Földani Intezete, Szeged,
Hungary.

*NATARAJAN, R., Marine Biological Station, Porto Novo, Madras State, India.

NATTKAMPER, G., I. Zool. Inst. d. Universitat, Dr. Karl Luegerring 1, A-1010,
Vienna, Austria.

NAWRATIL, O., I. Zool. Inst. d. Universitat, Dr. Karl Luegerring 1, A-1010,
Vienna, Austria.

NIEUWENHUIS, J. G., Bentincklaan 37 a, Rotterdam - C., The Netherlands.

NORELIUS, I., Zoologiska Institutionen, Lund, Sweden.

NORTON, P. E., Dept. of Zoology, The University, Glasgow У. 2., Scotland, U.K.

OKLAND, J., University of Oslo, Dept. of Anatomy, Blindern, Oslo 3, Norway.

OKLAND, K. A., Zool. Museum, University of Oslo, Sarsgt. 1, Oslo 5, Norway.

OBERZELLER, E., I. Zool. Inst. d. Universitat, Dr. Karl Luegerring 1, A-1010,
Vienna, Austria.

PAGET, O. E., Dept. of Mollusks, Museum of Natural History, Burgring 7, A-1010,
Vienna, Austria.

PARODIZ, J. J., Section of Invertebrates, Carnegie Museum, 4400 Forbes Avenue,
Pittsburgh, Pennsylvania 15213, U.S.A.

PEAKE, J. F., British Museum (Natural History), Cromwell Road, London S.W. 7,
England.

PETER, R., I. Zool. Inst. 4. Universität, Dr. Karl Luegerring 1, A-1010, Vienna,
Austria.

PETERSEN, H. G., Universitetets Zoologiske Museum, Universitetsparken 15,
Kgbenhavn, ®, Denmark.

PETITJEAN, M., Faculté des Sciénces d’Alger, Institut Oceanographique Jetée Nord,
Algiers, Algeria.

PICKRELL, D., 2, Hardenhuish Lane, Chippenham, Wiltsh., England.

POSCHACHER, E., Krottenbachstr. 52, A-1190, Vienna, Austria.

POSTMA, N., Zoologisch Laboratorium, Driehuizerweg 200, Nijmegen, The
Netherlands.

PURCHON, R. D., Dept. of Zoology, Chelsea College of Science & Technology,
Manresa Road, London, S.W. 3, England.

*RADIC, J. OFM, Zrtava Fasizma 1, Malakoloski Muzej, Makarska, Yugoslavia.
RADOMAN, P., Zoological Institute, Studentski Trg 3-4, Beograd, Yugoslavia.
RAVERA, O., Euratom C.C.R., Ispra (Varese), Italy.

*REGTEREN-ALTENA, C. O. van, Rijksmuseum van Natuurlijke Historie, Raamsteeg

2, Leiden, The Netherlands.
REMPE, J., Speelmanstraat 10, Amsterdam W II., The Netherlands.
RENZONI, A., Istituto di Zoologia, via Mattioli 4, Siena, Italy.

*RIEDEL, A., Instytut Zoologiczny, ul. Wilcza 64, Warszawa, Poland.

RIGBY, J., Dept. of Biology, Queen Elisabeth College, Campden Hill, London W. 8,
England.

ROOIJ-SCHUILING, L., Rijksmuseum van Natuurlijke Historie, Raamsteeg 2, Leiden,
The Netherlands.

RUNHAM, N. W., Dept. of Zoology, University College of North Wales, Bangor,
North Wales, U.K.

RUSS, K., Bundesanstalt f. Pflanzenschutz, Trunnerstr. 5, A-1020,Vienna, Austria.

311

SAHAI, B. N., Parasitology Dept. of Veterinary College, Patna, India.
SALVAT, B., Laboratoire de Malacologie, Muséum National d’Histoire Naturelle,
55, rue de Buffon, Paris Vf, France.
SALVINI-PLAWEN, Г. v., I. Zool. Inst. d. Universität, Dr. Karl Luegerring 1,
A-1010, Vienna, Austria.
SAUPE, E., Institut f. Parasitologie, Stephanstr. 15, D-63, Giessen, West Germany.
SCHALIE, H. van der, Museum of Zoology, The University of Michigan, Ann Arbor,
Michigan 48104, U.S.A.
SCHIEMA, F., Il. Zool. Inst. а. Universität, Dr. Karl Luegerring 1, A-1010, Vienna,
Austria.
SCHLICKUM, R., Hansaring 32, D-5 Köln, West Germany.
SCHUITEMA, A. K., Castorstraat 20, Delfzijl, The Netherlands.
SCHULLER, J., Fillgradergasse 3/II/11, A-1060, Vienna, Austria. (deceased).
SCHUTT, H., Haydnstr. 50, D-4 Diisseldorf-Benrath, West Germany.
*SCHWENGBERG, L., Senckenberg-Museum, Senckenberg-Anlage 25, D-6 Frankfurt/
M., West Germany.
*SESHAIYA, R. V., Marine Biological Station, Porto Novo, MadrasState, India.
SETTEPASSI, F., Istituto Italiano di Paleontologia Umana, via G. Caccini 1, Rome,
Italy.
SIEBER, R., Rasumovskygasse 23, A-1030, Vienna, Austria.
SMITH, M. F., National Museum of Canada, Ottawa, Ontario, Canada.
SNELI, J. A., Zool. Museum, University of Oslo, Sarsgatan 1, Oslo 5, Norway.
SOLEM, A., Field Museum of Natural History, Roosevelt Road at Lake Shore Drive,
Chicago, Illinois 60605, U.S.A.
SPAINK, G., Geologische Dienst, Spaarne 17, Haarlem, The Netherlands.
STARMUHLNER, F., I. Zool. Inst. d. Universitat, Dr. Karl Luegerring 1, A-1010,
Vienna, Austria.
STEININGER, F., Paläontol. Inst. d. Universität, Universitätsstr. 7/II, A-1010,
Vienna, Austria.
STOHLER, R., Dept. of Zoology, University of California, 4079 Life Science Bldg.,
Berkeley, California 94720, U.S.A.
STRAUCH, F., Geologisches Institut d. Universität, Zülpicherstr. 47, D-5 Köln,
West Germany.
TESTUD, A. M., Laboratoire de Malacologie, Museum d’Histoire Naturelle, 55,
rue de Buffon, Paris V*, France.
*THALER, E., Ignaz Harrerstr. 97, A-5020 Salzburg, Austria.
THOME, J. W., Museu Rio-Grandense de Ciencias Naturais, Av. Maua, 1855, Porto
Alegre, Rio Grande do Sul, Brasil.
TOFFOLETTO, F.; Museo Civico di Storia Naturale, viale Piceno 39, Milano, Italy.
ТВОЕМАМ, Е. R., Dept. of Zoology, University of Hull, Hull, England.
UETZ, K., Fleischmarkt 28, A-1010, Vienna, Austria.
URK, R. M. van, Rijksmuseum van Natuurlijke Historie, Raamsteeg 2, Leiden, The
Netherlands.
VISSER, G. J., Biologisch Station, Oosterend 71, Post Hoorn, Terschelling, The
Netherlands.
VOVELLE, J., Lab. Anatomie Comparée, Faculté des Sciénces, 7 quai St. Bernard,
Paris V*, France.
WAIDHOFER, C., I. Zool. Inst. d. Universität, Dr. Karl Luegerring 1, A-1010,
Vienna, Austria.
WALDEN, H. W., Naturhistoriska Museet, Göteborg 11, Sweden.
WARWICK, T., University of Edinburgh, Zool. Dept., West Mains Road, Edinburgh 9,
Scotland, U. K.

312

WIRTH, U., Drögestr. 2, D-2 Hamburg 33, West Germany.

WONDRAK, G., Elektronenmikroskop. Labor. d. Tierárztlichen Hochschule, Linke
Bahngasse 11, A-1030, Vienna, Austria.

*ZAMMIT-MAEMPEL, G., Natural History Museum, 53 Main Street, Birkirkara,

Malta.
ZILCH, A., Senckenberg-Museum, Senckenberg-Anlage 25, D-6 Frankfurt/M., West
Germany.

By an unfortunate oversight the name of Dr. B. C. Dazo was ommitted completely in
the Proceedings of the Second Malacological Congress in Copenhagen. Therefore it
should be mentioned that Dr. Dazo, who is member of the Unitas Malacologica Europaea,
was a participant of the Second Congress and presented a paper there on “Determining
sites of bilharzial transmission.”

INDEX TO SCIENTIFIC NAMES

aberrans, Veronicella, 264 adriatica, Trivia, 232, 235, 236, 241
Abida, 112, 115, 117 adriatica, Distoma, 231
frumentum, 112, 115, 117 Aegopinella, 269
Abra, 238, 241, 271, 277 nitidula, 269
alba, 238, 241 Aegopis, 86, 117
ovata, 277 verticillus, 117
profundorum, 271 Aenigma, 83
abrotanifolia, Cystoseiva, 277, 230 rosea, 83
Acanthinula, 85, 115, 297 aenigmatica, Enigmonia, 288
aculeata, 85, 115, 297 Aeolidiacea, 230, 231, 282, 295
Acanthochiton, 210, 227, 228, 230, 231, аетеа, Chaetomorpha, 224
240 Aeromonas, 43
communis, 227, 228, 230, 231, 240 liquefaciens, 43
fascicularis, 227, 240 affinis, Flabellina, 230, 231, 237
Acar, 271 Afriboysidia, 256
asperula, 271 africana, Macroptychia, 258
Acavidae, 256-258 africanus, Bulinus, 30
Acetabularia, 224, 227, 230 Afrodonta, 256
mediterranea, 224, 227 aggevicola, Arion, 73
achates, Chilostoma achates, 261 Aglaophenia, 225, 226
achates achates, Chilostoma, 261 pluma, 225
Achatina, 43 agraulus, Gyraulus, 88
fulica, 43 Agriolimax, 179-182, 184, 273
Achatinacea, 260 caruanae, 273
Achatinellacea, 260 reticulatus, 179-182, 273
Achatinidae, 256, 257 Ailanthus, 85
Acicula, 117 Akiyoshia, 278
polita, 117 alata, Isognomum, 80, 83
acicula, Eulimella, 238 alba, Abra, 238, 241
acicularis audebartii, Fagotia, 113 albescens, Doris, 96
aciculata, Tritonalia, 226, 228, 230, 231, albus, Gyraulus, 56, 145
240 albus, limophilus, Gyraulus, 56
Acmaea, 81 Alexandromenia, 204
Acme, 249 crassa, 204
inchoata, 249 Alexia, 224, 240
Acroloxus, 145 myosotis, 224, 240
lacustris, 145 alliarius, Oxychilus, 273, 274
acronicus, Gyraulus, 145, 149 alluaudi, Bulinus tropicus, 38
Acteon, 232, 236, 241 Alloidis, 238, 241
tornatilis, 232, 236, 241 gibba, 238, 241
Actinia, 224 alticola, Columella, 297
equina, 224 Alvania, 230-232, 234, 238, 240, 241, 243
aculeata, Acanthinula, 85, 115, 297 cimex, 230-232, 234, 238, 240, 241
aculeata, Crepidula, 81 Alzonula, 86
Aculifera, 191, 193, 195, 205, 209, 210, oglasicola, 86
212, 214 Amanthia, 230
acultiliva, Sinuitopsis, 201 Ambigua, 85, 88
acuta, Cochlicella, 88 argentarolae forsythi, 88
acuta, Hydrobia, 277 forsythi, argentarolae, 88
acuta, Physa, 54, 55, 277 amboinensis, Anamenia, 204
Adesmacea, 164 ameghini, Veronicella, 264
adriatica, Cystoseiva, 227 americanus, Modiolus, 80, 83

(313)

314

Ammonoidea, 209
Amnicolinae, 278
Amphibulimidae, 256
Amphineura, 191, 193, 210, 214
Amphipoda, 271
Anadara, 80, 83, 165, 168
gvanosa, 83, 165, 168
notabilis, 80, 83
Anamenia, 204
amboinensis, 204
anatina, Pseudamnicola, 277
Anatinacaea, 170
anceps voyalense, Helisoma, 263
Anchinoe, 226
anchora, Gymnarion, 60
Ancylidae, 145
Ancylus, 54, 55, 145, 148, 277
costulatus, 54, 55
fluviatilis, 55, 145, 148, 277
Aneitea, 259, 260
angigyra, Helicodonta, 267
anguistipes, Veronicella, 264
angulifera, Littorina, 80, 82
Angulus, 238, 241
incarnatus, 238
planatus, 238
Anisomyaria, 163
Anisus, 55, 56, 145
perezi, 56
spirorbis, 55, 145
Annelida, 203, 210
annularis, Phenacolimax, 117
annulata, Pyrgula, 175, 176
Anodonta, 67, 68, 247, 286
cellensis, 67, 68
cygnaea, 286
Anomalocardia, 81, 83
brasiliana, 81, 83
Anomia, 227, 240, 288
ephippium, 227, 240
patelliformis, 288
Anomiidae, 83, 164
Anthozoa, 212, 219
antiqua, Succinea, 249

antivertigo, Vertigo, 115, 117, 249

Antroselates, 278

Apera, 256

Aperidae, 256-258

aperta, Cantareus, 88
aperta, Helix, 88

aperta, Philine, 234, 236, 241
apicina, Helicella, 88

apicina, Xerotrichia, 88
Aplacophora, 191, 193, 195, 214
Aplexa, 145
hypnorum, 145
Aplidium, 231
conicum, 231
Aplysia, 253
depilans, 253
fasciata, 253
punctata, 253
Aporrhais, 231, 232, 234, 235, 238, 240,
241
pes pelecani, 231, 232, 234, 235, 238,
240, 241
arboreus, Zonitoides, 297
arbustorum, Arianta, 249
Arca, 165, 168, 188, 189, 226, 227, 232,
234, 238-241, 271
barbata, 234
lactea, 226, 227, 234, 238-241
noae, 232, 234
orbiculata, 271
similis, 165, 168
ventricosa, 188, 189
Arcacea, 163
Archaeogastropoda, 279
Archiannelida, 208
Archicoelomata, 213
Archidoris, 232, 234, 236, 237, 240, 241
tuberculata, 232, 234, 236, 237, 240,
241
Archivesica, 254
Archoophora, 203
Arcidae, 83, 164
Arcopagia, 238
balaustina, 238
arctica, Hiatella, 291, 292
arctica, Vertigo, 297, 299
arcuata, Melanella, 238
arcuatus, Ensis, 245, 246
arenaria, Catinella, 117
argentaricus, Oxychilus, 86
argentarolae forsythi, Ambigua, 88
argentarolae forsythi, Marmorana, 88
Arianta, 249
arbustorum, 249
arigoi, Leucochroa, 55
arigoi, Xeromagna, 55
Arion, 73-78, 249, 297, 303
aggericola, 73
ater, 73, 76, 249
ater ater, 73, 76

ater rufus, 73
aterrima, rufus ата, 13
atra, rufus, 73
atra aterrima, rufus, 73
ата marginella, rufus, 73, 74
ата sulcata, rufus, 73, 74
brevieri, 73
circumscriptus, 297
fasciatus, 297
flavus, 73
hibernus, 73
intermedius, 249
lusitanicus, 73-77
lusitanicus nigrescens, 73
marginella, rufus ата, 73, 74
nigrescens, lusitanicus, 73
nobrei, 73
rubiginosus, 73
rufus, 73, 74, 76, 303
rufus, ater, 73
rufus atra, 73
rufus atra aterrima, 73
rufus atra marginella, 73, 74
rufus atra sulcata, 73, 74
silvaticus, 297
subfuscus, 73, 74, 76, 249
sulcata, rufus ата, 73, 74
sulcatus, 76
tenellus, 73
virescens, 73
Arionidae, 73, 256, 258
Ariophantacea, 260
Armiger, 56, 85, 87
crista, 56, 85, 87
Artemisia, 249
Articidae, 254
Asaphidae, 83
Asaphis, 81, 83
deflorata, 81, 83
Ascidia, 81, 219, 222, 226, 231, 234, 240
mentula, 231
nigra, 81
virginea, 231
Ashfordia, 249
granulata, 249
aspera, Columella, 249, 297
aspersa, Cryptomphalus, 55, 86, 87
aspersa, Helix, 55, 86, 87, 135, 273, 303
asperula, Acar, 271
Astarte, 168
Astartidae, 254
Astraea, 231, 234, 240, 241
rugosa, 231, 234, 240, 241

315

Astralium, 293
ater, Avion, 73, 76, 249
ater, Arion ater, 73
ater, Viviparus, 284
ater ater, Arion, “3, 76
ater rufus, Avion, 73
aterrima, Arion rufus atra, 73
Athoracophoracea, 260
Athoracophoridae, 259, 260
Athopos, 282
atlantica, Callocardia, 254
atra, Arion rufus, 73
atra aterrima, Arion rufus, 73
atra marginella, Arion rufus, 73, 74
atra sulcata, Avion rufus, 73, 74
Atrina, 165
atriolonga, Genitoconia, 204
atromaculata, Peltodoris, 220, 226, 227,
237, 240
audebartii, Fagotia acicularis, 113
Aulacopoda, 260
aurantia, Caloplaca, 223
aurantiaca, Bouvieria, 232, 234, 240
auratus, Cricetus, 30
aurea, Venerupis, 275
auricula, Auriculella, 260
auricularia, Lymnaea, 145
auricularia, Radix, 54, 55
Auriculella, 260
auricula, 260
auris judae, Ellobium, 82
auris midae, Ellobium, 82
aurita, Eumorphotis, 288
Australorbis, 31, 104, 105
glabratus, 31, 104, 105
Avenionia, 278
Avicennia, “9
nitida, 79
Aviculidae, 164
axinellae, Parazoanthus, 226

Babinka, 201

Baicalia, 176

baicaliiformis, Stankovicia, 176
Baicaliinae, 175, 176

Bakevilliidae, 288

Balanidae, 226

Balanus, 81

baldensis, Chilostoma cinculatum, 261
balustina, Acropagia, 238

banatica, Helicigona, 117
banyulensis, Nematomenia, 207, 209
barbara, Cochlicella, 89

316

barbata, Arca, 234
barbata, Cystoseiva, 224
barbatus, Modiolus, 234, 238, 241
Barnea, 167-170
Basommatophora, 39, 101
Bathyomphalus, 145
contortus, 145
Batillaria, 81, 82
minima, 81, 82
Beguinea, 226, 227, 231, 240
calyculata, 226, 227, 231, 240
Belgrandia, 117
tataénsis, 117
Bellerophontacea, 201
Berthelinia, 81
caribbea, 81
bidentata, Perforatella, 113, 115
bidentatus, Melampus, 81, 82
bielzi, Mastus, 117
bielzi, Vitrina, 117
Bilateria, 205
binneyana, Nesovitrea, 297
Biomphalaria, 25, 32, 35, 40, 43
glabrata, 25, 32, 40
pfeifferi, 35, 43
sudanica tanganyicensis, 35
tanganyicensis, sudanica, 35
biplicata, Laciniaria, 299
biplicata, Olivella, 290
birmanica, Nerita, 82
bistrialis, Cryptozona, 260
bisulcata, Lithophaga, 81
Bithynia, 113, 277
tentaculata, 277
tentaculata thermalis, 113
thermalis, tentaculata, 113
Bittium, 220, 228, 230, 231, 234, 238,
240, 241
reticulatum, 228, 230, 231, 234, 238,
240, 241
Bivalvia, 163, 164, 166, 191, 201, 203-
210, 214, 217, 219, 222, 225-227,
230, 231, 234, 236, 238, 240, 241,
243, 247, 254, 275, 288
blainvillei, Murex, 220
blainvillei, Muricidea, 226, 227, 230, 240
böcklii, Viviparus, 112
bohemica, Hercynella, 288
Bonellia, 205, 212
borellianus, Vaginulus, 284
Bosellia, 220, 226, 237, 240

mimetica, 220, 226, 237, 240
Bostrychia, 81
Bothryllus, 81
Botryocladia, 230
botryoides, 230
botryoides, Botryocladia, 230
Bouvieria, 232, 234, 240
aurantiaca, 232, 234, 240
Brachidontes, 80, 81, 83
citrinus, 80
exustus, 80, 81, 83
recurvus, 80
Brachiopoda, 210, 213, 288
Brachyodontes, 220, 224, 225, 231, 238,
240
minimus, 220, 224, 225, 231, 238, 240
Bradybaenidae, 262
branchialis, Favorinus, 230, 231
brandaris, Murex, 238, 241
brasiliana, Anomalocardia, 81, 83
Brechites, 168
breve, Vitrinobrachium, 269
brevierei, Arion, 73
brevifrons, Murex, 80, 82
britannica, Truncatellina, 249
Bryozoa, 193, 210, 222, 230
Buccinidae, 222, 226, 227
Bufo, 286
melanostictus, 286
Bulininae, 26
Bulinus, 25-33, 35, 37-39
africanus, 30
alluaudi, tropicus, 38
contortus, 26
coulboisi, 38
depressus, 37
globosus, 35
guernei, 37, 38
nasutus, 35
natalensis, 37, 38
rohlfsi, truncatus, 38
sericinus, 37
tropicus, 37-39
tropicus alluaudi, 38
tropicus tropicus, 38
truncatus, 25, 26, 28, 29, 31-33, 37, 38
truncatus rohlfsi, 38
truncatus truncatus, 38
ugandae, 35
Bulla, 81
bullaoides, Detraci, 82

Bullaria, 236, 241
striata, 236, 241
bursa, Codium, 225
Bythinella, 173, 174
robiëi, 173
Bythinellinae,
Bythiniinae,

278
278

Cacopus, 287
systoma, 287
Cacospongia, 225, 226
scalaris, 225, 226
Caecum, 236, 241
glabrum, 236, 241
caespitosa, Hyella, 223
cajetanus, Lepidopleurus, 227, 240, 241
calcara, Doris, 96
californica, Dondersia, 204
californicum, Prochaetoderma, 206
Calliostoma, 230, 231, 236, 241
conulus, 231
laugieri, 230
zizyphinus, 231
Callocardia, 254
atlantica, 254
Callochiton, 220, 226, 234, 240
laevis, 220, 226, 234, 240
Callogonia, 254
callosa, Vertigo, 112
Calmella, 230, 231
cavolini, 230, 231
Caloplaca, 223
aurantia, 223
calyculata, Beguinea, 226, 227, 231, 240
Calyptogena, 254
Calyptraea, 231, 234, 240, 241
sinensis, 231, 234, 240, 241
campanulatum, collinsi, Helisoma, 263
Campylaeinae, 261, 262
cancellata, Chione, 81, 83
cancellatus, Lepidopleurus, 236
Candidula, 261, 262
gigaxi, 261, 262
intersecta, 261
Cantareus, 88
aperta, 88
Cantharidus, 228, 230, 231, 238, 240, 241
exasperatus, 228, 230
striatus, 230, 238, 241
Cantharus, 220, 225-227, 230, 235, 240
d’orbigny, 220, 225-227, 230, 235, 240
cantrainii, Chromodoris, 96

317

caprai, Lehmannia, 86
caprearum, Middendorfia, 220, 224, 225,
240
Capulus, 227, 231, 232, 234, 240, 241
hungaricus, 227, 231, 232, 234, 240,
241
Caracollina, 88, 90
lenticula, 88
Cardiacea, 222, 231
cardissa, Corculum, 288
Cardita, 288
partschi, 288
Carditidae, 254
Cardium, 168, 169, 231, 234, 238, 240,
241, 277
exiguum, 231, 234, 238, 241
glaucum, 277
paucicostatum, 238, 241
tuberculatum, 238
Carex, 302
caribbea, Berthelinia, 81
carinata, Neomenia, 207, 208, 210
carinata, Potamorpyrgus jenkinsi, 301
carinatus, Mecynodon, 288
carinatus, Planorbis, 145
carnea, Ferrussacia, 90
carnea, Pegea, 90
Carolia, 288
cartusiana, Monacha, 55
caruanae, Agriolimax, 273
caruanae, Deroceras, 86, 87
Carychium, 115, 117, 297
minimum, 115, 117
casertanum, Pisidium, 268
casina, Venus, 238, 241
Cassidaria, 231
echinophora, 231
Cassidula, 280
catascopium nasoni, Lymnaea, 263
catascopium preblei, Lymnaea, 263
Catinella, 117, 259, 260, 289
avenaria, 117
vermeta, 260
Catinellinae, 289
catskillensis, Discus cronkhitei, 260
Caudofoveata, 191, 193-195, 199-201,
203-206, 209, 212-214
Caulerpa, 81
cavolini, Calmella, 230, 231
cavolinii, Dynamena, 225
cayenensis, Diodora, 81
cellarius, Oxychilus, 269, 273

318

cellensis, Anodonta, 67, 68
Cepaea, 55, 261
nemoralis, 55
hortensis, 261
Cephalaspidea, 204, 236, 238, 241, 282
Cephalopoda, 201, 203, 217, 243, 247
Ceramium, 230
Cerithidea, 81, 82
costata, 81, 82
obtusa, 82
Cerithiidae, 82
Cerithium, 81, 82, 225, 231, 234, 238,
240, 241
eburneum, 82
litteratum, 82
patulum, 82
vupestre, 225, 234, 238, 240, 241
variabile, 81
vulgatum, 231, 234, 240, 241
Cernuella, 55, 85
profuga, 85
virgata, 55
Chaetoderma, 193, 204
Chaetodermatida, 195
Chaetodermatidae, 191, 195, 204
Chaetognatha, 212, 213
Chaetomorpha, 224
aerea, 224
chaixii, Mesodontopsis, 87
chaixii, Tacheocampylaea, 87
Chama, 80, 168, 169, 188, 225, 227, 240
congregata, 80
gryphina, 225, 240
gvyphoides, 225, 240
imbricata, 188
macerophylla, 80
chamaeleon, Nerita, 280, 281
Charopinae, 289
Chaenopodiaceae, 249
Chilopyrgula, 173, 176
zilchi, 176
Chilostoma, 85, 87, 261
achates achates, 261
baldensis, cingulatum, 261
cingulatum baldensis, 261
intermedium, 261
illyrica, planospiva, 261
occultata, planospiva, 85, 87
planospira illyrica, 261
planospira occultata, 85, 87
Chione, 81, 83
cancellata, 81, 83
chione, Pitaria, 231, 234, 240

Chiton, 210, 224-227, 230, 231, 234, 240
corallinus, 226, 234, 240
olivaceus, 224, 225, 227, 230, 231, 240

Chlamys, 231, 234, 238, 240, 241, 247

Chondrinidae, 256

Chondrocyclus, 256

Chondrosia, 226
veniformis, 226

Chondrula, 117
tridens, 117

Chordonia, 213

Chromodoris, 93, 96
cantrainii, 96
elegantula, 93
theringi, 96
luteorosea, 96
trilineata, 96
villafranca, 96

Chrysallida, 238, 241
interstincta, 238

Chthamalus, 223
depressus, stellatus, 223
stellatus, 223
stellatus depressus, 223
stellatus stellatus, 223

cimex, Alvania, 230-232, 234, 238, 240,

241

Cionellacea, 260

cingulatum baldensis, Chilostoma, 261

cinctella, Hygromia, 89

circumscriptus, Arion, 297

Cistus, 54

citrinus, Brachidontes, 80

Cladophora, 224, 225
pellucida, 224

clarai, Claraia, 288

Claraia, 288
clarai, 288

Clausilia, 113, 117, 249, 297
cruciata, 113
dubia, 297
pumila, 117, 249, 297

Clausiliidae, 258

claustralis, Truncatellina, 115

Clithon, 279
vetropictus, 279

Cnidaria, 195, 226

Cochlicella, 55, 88, 89, 262
acuta, 88
barbara, 89
conoidea, 55

Cochlicopa, 249, 297
lubrica, 249

Cochlodina, 87, 88, 90
küsteri, 87, 88
meisneriana, 87, 88
porroi, 87, 88
sancta, 88
sarda, 88
sophiae, 88
Cochlostoma, 112
Codium, 225
bursa, 225
Codokia, 288
Coeliaxis, 256
coelestis, Glossodoris, 96, 98
coelestis, Goniodoris, 96
Coelomata, 203
coerulea, Patella, 220, 224, 225, 240
coffeus, Melampus, 81, 82
collinsi, Helisoma campanulatum, 263
Columbella, 82, 225, 230, 231, 238, 240,
241
mercatoria, 82
rustica, 225, 230, 231, 238, 240, 241
columbella, Linga, 288
Columella, 117, 249, 297, 299
alticola, 297
aspera, 249, 297
columella, 117, 249, 297, 299
edentula, 297
simplex, 297
columella, Columella, 117, 249, 297, 299
columna, Gymnarion, 60
colymbus, Pteria, 80
communis, Acanthochiton, 227, 228, 230,
231, 240
communis, Turritella, 232, 238, 241
compacta, Pseudamnicola, 277
complanatus, Hippeutis, 56, 145
compressa, Septaria, 280, 281
Conchifera, 191, 193, 199, 201, 203, 206,
210, 212, 214
confervoides, Lyngbyia, 224
confinis, Lichina, 223
Congeria, 288
subglobosa, 288
Congeriomorpha, 288
congregata, Chama, 80
conicum, Aplidium, 231
Conocarpus, 79
erectus, “9
conoidea, Cochlicella, 55
consobrinus, Lamellidens, 286
consociella, Hydrobia, 174
consociella, Pseudamnicola, 173

319

conspurcata, Helicella, 55, 88
conspurcata, Xerotricha, 55, 88
constrictus, Trissexodon, 267
contortus, Bathyomphalus, 145
contortus, Bulinus, 26
contracta, Vitrea, 85, 87
conulus, Calliostoma, 231
Conus, 225, 226, 228, 230, 231, 238, 240,
241
ventricosus, 225, 226, 228, 230, 231,
238, 240, 241
conventus, Pisidium, 123, 124, 268
convexa, Crepidula, 81
Corallina, 224, 225
mediterranea, 224, 225
corallina, Mactra, 245
corallinus, Chiton, 226, 234, 240
Corbicula, 112, 264
fluminalis, 112
fluminea, 264
Corculum, 288
cardissa, 288
Corillidae, 256
corneus, Planorbarius, 145
corniculata, Cystoseiva, 227
cornuarietis, Marisa, 40
corona, Melongena, 81
coronata, Idulia, 228, 230, 231
coronata, Runcina, 238, 241
coronatus, Gymnarion, 60, 64
corpulentum vermilionense, Helisoma,
263
corpulentum whiteavesi, Helisoma, 263
corrianus, Lamellidens, 286
corrugata, Parreysia, 286
corsicus, Limax, 89
corvus, Galba, 42
Coryphella, 230, 231
lineata, 230, 231
costata, Cerithidea, 81, 82
costata, Vallonia, 55, 112, 115, 117, 249
costulatus, Ancylus, 54, 55
coulboisi, Bulinus, 38
crassa, Alexandromenia, 204
Crassostrea, 80, 83
parasitica, 83
rhizophorae, 80, 83
virginica, 80
Crepidula, 81, 231, 239
aculeata, 81
convexa, 81
crepidularia, Dostia, 280, 281
crepidularia, Neritina, 281

320

Cricetus, 30 Dendrodoris, 232, 234, 240
auratus, 30 limbata, 232, 234, 240
crinita, Cystoseiva, 227, 230 dentale, Dentalium, 207, 232, 236, 241
crista, Armiger, 56, 85, 87 Dentalium, 207, 209, 210, 232, 236, 238, 241
crista, Gyraulus, 145 dentale, 207, 232, 236, 241
cristata, Valvata, 145 panormitanum, 238, 241
cronkhitei, Discus, 260 vulgare, 236, 241
crossotus, Falcidens, 206 depilans, Aplysia, 253
cruciata, Claustlia, 113 depressa, Psammobia, 238
Cryptomphalus, 55, 86, 87 depressus, Bulinus, 37
aspersa, 55, 86, 87 depressus, Chthamalus stellatus, 223
Cryptozona, 260 depressus, Oxychilus, 117
bistrialis, 260 Deroceras, 86, 87, 90, 249, 297
crystallina, Vitrea, 85, 87 caruanae, 86, 87
cuneata, Malletia, 271 laeve, 297
curta, Pseudamnicola, 174 sturanyi, 297
Cuspidaria, 168 despectus, Tergipes, 236, 241
Cyclomenia, 204 Detracia, 81, 82
holoserica, 204 bullaoides, 82
Cyclopecten, 271 Deuterostomia, 205, 210, 213
undatus, 271 Diana, 173, 174, 176
Cyclophoridae, 256 grochmalickii, 174
cydonium, Geodia, 231, 232 prespensis, 174, 176
cygnaea, Anodonta, 286 schlikumi, 176
cylindracea, Lauria, 56, 89 thiesseana, 173, 174, 176
cylindrica, Truncatellina, 112, 115, 249 diaphana, Eucobresia, 249, 269
Cylindrus, 249, 251 diaphana, Vitrea, 87
obtusus, 249, 251 Diaphorodoris, 93, 98
Cypraea, 82 luteocincta papillata, 93, 98
zebra, 82 papillata, luteocincta, 93, 98
Cyrtollites, 201 dibothryon, Perforatella, 117
ornatus, 201 Dibranchiata, 209
Cyrtonella, 201 Dicevas, 288
Cystoseiva, 222, 224, 227, 228, 230, 231, Dictyota, 230
240 Digena, 228
abrotanifolia, 227, 230 simplex, 228
adriatica, 227 Dimyidae, 163
barbata, 224 diodonta, Soosia, 117
corniculata, 227 Diodora, 81, 225-227, 231, 234, 240
crinita, 227, 230 cayenensis, 81
mediterranea, 224 gibberula, 227
spicata, 227, 230 graeca, 225-227, 240
Cythara, 238, 241 italica, 231, 234, 240
Diotocardia, 212
аа, Limopsis pelagica, 271 Diplacophora, 201
danubialis, Trichia striolata, 261 Discinae, 289
Daonella, 288 Discus, 249, 260, 299
darieuxi, Pyrgula, 176 catskillensis, cronkhitei, 260
Decabrachia, 209 cronkhitei catskillensis, 260
decollata, Rumina, 55 rotundatus, 249
decussata, Venerupis, 275, 276 ruderatus, 299

deflorata, Asaphis, 81, 83 Distoma, 231

adriaticum, 231
distorta, Tellina, 232, 236, 239, 241
divaricata, Divaricella, 236, 241
Divaricella, 236, 241

divaricata, 236, 241
dofleini, Octopus, 247
dohrni, Hypnophila, 85, 88
dombeyi, Nerita, 280, 281
Donacidae, 164, 170
Donax, 238, 241

trunculus, 238
Dondersia, 204

californica, 204
d’orbigny, Cantharus, 220, 225-227, 235,

240
Dorcasia, 256
Doridacea, 234, 282
Dorididae, 226
Doris, 96, 97

albescens, 96

calcara, 96

elegans, 96

gracilis, 96

lutescens, 96, 97

nardii, 96

orsinii, 96

pallens, 96

parthenopeia, 96

pasinii, 96

picta, 96

pirainii, 96

pulcherima, 96

scacchiana, 97

schultzii, 97

tenera, 96

venulosa, 96

villae, 96

villafranca, 96
Dorymenia, 204

weberi, 204
Dosinia, 275, 276

exoleta, 275, 276
Dostia, 279-281

crepidularia, 280, 281

violacea, 279
dovrense, Taraxacum, 249
Drahomira, 201
draparnaudi, Oxychilus, 269
Dreissena, 168, 169, 207

polymorpha, 207
Drepanostoma, 267

nautiliforme, 267
drummondi, Facelina, 230, 231

321

dubia, Clausilia, 297
dubia, Gastrochaena, 220, 224-227, 238-
240
duplex, Gymnarion, 60, 64
Dynamena, 225
cavolinii, 225

eburneum, Cerithium, 82
echinophora, Cassidaria, 231
Echiurida, 203, 205, 212
edentula, Columella, 297
edulis, Ostrea, 220, 224-227, 240
edwardsi, Tritonalia, 226, 227, 230, 240
Egeria, 167, 168, 170
elata, Tacheocampylaea, 87
electrina, Nesovitrea, 297
Eledone, 246
elegans, Doris, 96
elegans, Pomatias, 87, 117
elegans, Sidonia, 282
elegantula, Chromodoris, 93
elegantula, Glossodoris, 93, 98
Ellobiidae, 81-83
Ellobium, 82
auris judae, 82
auris midae, 82
Elysia, 228, 230, 231, 238, 240, 241
viridis, 228, 230, 231, 238, 240, 241
Emarginula, 81, 227, 240
pumila, 81
Embletonia, 236, 241
pulchra, 236, 241

Emmericia, 175, 278
Emmericiinae, 278
Ena, 56

obscura, 56
Endocochlia, 209
Endodontacea, 260
Endodontidae, 256, 258
Endodontinae, 289
Enidae, 256
Enigmonia, 288
aenigmatica, 288
enniensis, Vallonia, 115, 117
Ensis, 168, 238, 245-247
arcuatus, 245, 246
ensis, 238
siliqua, 238
ensis, Ensis, 238
Enteromorpha, 224
Enteropneusta, 204, 205, 213
Entophysalis, 223

322

granulosa, 223
Entoprocta, 212
Eobania, 55

vermiculata, 55
ephippium, Anomia, 227, 240
Epimenia, 204, 207, 209, 210

verrucosa, 204, 207, 209
Epizoanthus, 226
equina, Actinia, 224
erectus, Conocarpus, “9
etrusca, Hypnophila, 88
Eucobresia, 249, 269

diaphana, 249, 269
Euconulus, 249, 297

fulvus, 249
Eulamellibranchia, 163-165
Eulamellibranchiata, 121
Eulimella, 238, 241

acicula, 238
Eumorphotis, 288

aurita, 288

telleri, 288
Euparypha, 55

pisana, 55
europeense, Schistosoma haematobium,

Euthyneura, 253, 259, 282
exasperatus, Cantharidus, 228, 230
excavatus, Zonitoides, 249, 269
exiguum, Cardium, 231, 234, 238, 241
exoleta, Dosinia, 275, 276
expansum, Pseudolithophyllum, 225, 226
exustus, Brachidontes, 80, 81, 83

Facelina, 230, 231
drummondi, 230, 231
Fagotia, 113
acicularis audebartii, 113
audebartii, acicularis, 113
Falcidens, 204, 206
crossotus, 206
fallaciosa, Planispira, 260
fasciata, Aplysia, 253
fasciatus, Avion, 297
fascicularis, Acanthochiton, 227, 240
Fasciola, 42, 127
hepatica, 42, 127
fasciola, Lampsilis, 272
Fasciolaria, 82
tulipa, 82
fauntandraui, Glossodoris, 96
Fauxulus, 256

Favorinus, 230, 231

branchialis, 230, 231
Ferrussacia, 90

carnea, 90
ficiformis, Petrosia, 220, 226, 227, 240
Filibranchia, 164, 165
filocincta, Micromelania, 176
Fimbria, 295, 296

fimbria, 295, 296
fimbria, Fimbria, 295, 296
Flabellina, 230, 231, 237

affinis, 230, 231, 237
flavus, Arion, 73
flavus, Limax, 87, 273
fluminalis, Corbicula, 112
fluminea, Corbicula, 264
fluminensis, Sadleriana, 174
Flustra, 222, 234
fluviatilis, Ancylus, 55, 145, 148, 227
fluviatilis, Theodoxus, 279
foliacea, Hippodiplosia, 232
foliata, Trinchesia, 230, 231
Fontigens, 278
Fontinalis, 268
fontinalis, Physa, 145
forsythi, Ambigua argentarolae, 88
forsythi, Marmorana argentarolae, 88
Fosliella, 224, 230, 240
fragilis, Gastrana, 238
fragilis, Leda, 238
fvons, Ostrea, 80
frumentum, Abida, 112, 115, 117
fulica, Achatina, 43
fulvus, Euconulus, 249
Fusus, 230

gachua, Ophiocephalus, 286
gagathinella, Hydrobia, 174
Galba, 42, 55, 89

corvus, 42

glabra, 42

palustris, 42

truncatula, 42, 55, 89
gallina, Venus, 238
galloprovincialis, Mytilus, 224-226, 240
Gari, 83

togata, 83
Gasteropteron, 207

vumbrum, 207
Gastrana, 238

fragilis, 238
Gastrochaena, 220, 224-227, 238-240

dubia, 220, 224-227, 238-240
Gastrocopta, 113, 115

serotina, 113, 115
Gastrodontinae, 269
Gastroneuralia, 212, 213

Gastropoda, 101, 143, 201, 203, 204, 207,
210, 212.213, 211. 224227. 230,
231, 234, 236, 240, 241, 243, 253,

259, 267, 282, 284, 293
genesii, Vertigo, 291, 299
Genitoconia, 204

atriolonga, 204
Geodia, 222, 231, 232, 234, 240
cydonium, 231, 232
Geomalacus, 249
maculosus, 249
Gervillia, 288
geyeri, Vertigo, 297
gibba, Aloidis, 238, 241
gibberula, Diodora, 227
Gibbula, 230, 238, 240, 241, 293, 294
magnus, 293
varia, 230, 238, 241
gigaxi, Candidula, 261, 262
Ginaia, 176
glabra, Galba, 42
glabra, Lymnaea, 145
glabrata, Biomphalaria, 25, 32, 40
glabrata, Neritina, 47-51
glabratus, Australorbis, 31, 104, 105
glabrum, Caecum, 236, 241
glandulifera, Microhedyle, 236, 241
glaucum, Cardium, 277
globosus, Bulinus, 35
Glossodoridinae, 93, 97, 98
Glossodoris, 93-98, 234, 241
coelestis, 96, 98
elegantula, 93, 98
fauntandraui, 96
gracilis, 93, 94, 96, 98, 234, 241
krohni, 93, 94, 96
luteorosea, 93, 94, 96
messinensis, 93, 95, 96, 98
purpurea, 95, 96
tricolor, 93, 95, 96, 98
valenciennesi, 93, 95-98
Glossus, 168, 169
glutinosa, Lymnaea, 145
Glycymeris, 168, 288
pilosa, 288
Gocea, 173
ohridana, 173

323

Goniodoris, 96

coelestis, 96
Gorgonaria, 80
gorgonianus, Oxychilus, 86
gracilis, Doris, 96
gracilis, Glossodoris, 93, 94, 96, 98,

234, 241

graeca, Diodora, 225-227, 240
Grammysia, 288

nodocostata, 288

undata, 288
gvanifeva, Tarebia, 40
Granopupa, 55, 85, 88-90

granum, 55, 85, 89

philippi, 85, 88
granosa, Anadara, 83, 165, 168
granulata, Ashfordia, 249
granulosa, Entophysalis, 223
gvanum, Granopupa, 55, 85, 89
gratiosa, Pupa, 56
grochmalickii, Diana, 174
grochmalickii, Hydrobia, 173
grochmalickii, Pyrgohydrobia, 173
Gryphaea, 288
gryphina, Chama, 225, 240
gvyphoides, Chama, 225, 240
guernei, Bulinus, 37, 38
guidonii, Hyalinia, 86
guillemini, Polynices, 236
guyannensis, Mytella, 80
Gymnarion, 59, 60, 63, 64

anchora, 60

columna, 60

coronatus, 60, 64

duplex, 60, 64
Gyraulus, 56, 88, 145, 149, 173

acronicus, 145, 149

agraulus, 88

albus, 56, 145

albus limophilus, 56

crista, 145

laevis, 145

limophilus, albus, 56

relictus, 173

haematobium, Schistosoma, 25-27, 29-33,
37
haematobium europeense, Schistosoma,
26
Halichondria, 225
panicea, 225
Halimeda, 220, 226, 228, 230, 240

324

tuna, 220, 226, 228, 230, 240
Haliotis, 227, 230, 240
lamellosa, 227, 240
tuberculata, 230
Halomenia, 210
Haminea, 236
hydatis, 236

hammonis, Nesovitrea, 115, 249, 297

Hedylopsis, 236, 241
spiculifera, 236, 241

helgolandica, Philinoglossa, 236, 241

Helicacea, 260
Helicella, 55, 88, 112, 115, 117, 303
apicina, 88
conspurcata, 55, 88
hungarica, 112, 115, 117
obvia, 303
striata, 112
Helicellinae, 261, 262
Helicidae, 261, 262, 269, 289
Helicigona, 85, 87, 117, 249
banatica, 117
lapicida, 249
occultata, planospira, 85, 87
planospiva occultata, 85, 87
Helicinae, 262
Helicodonta, 267
angigyva, 267
obvoluta, 267
Helicodontinae, 262, 267
Helisoma, 263
anceps royalense, 263
campanulatum collinsi, 263
collinsi, campanulatum, 263
corpulentum vermilionense, 263
corpulentum whiteavesi, 263
royalense, anceps, 262
vermilionense, corpulentum, 263
whiteavesi, corpulentum, 263
Helix, 55, 86-88, 90, 135-139, 153,
156, 158-162, 261, 267, 273,
303
aperta, 88
aspersa, 55, 86, 87, 135, 273, 303
pomatia, 135, 139, 153, 261, 303
quadrasi, 267
rumelica, 135
subconstrictus, 267
helminthoides, Nemalion, 224
Hemichordata, 203
Hemimykale, 226
Нетйота, 81
octoradiata, 81

Heminerita, 279
japonica, 279
hepatica, Fasciola, 42, 127
Hercynella, 288
bohemica, 288
Hervia, 230, 231
peregrina, 230, 231
Heterurethra, 259, 260
hexadactyla, Rana, 286
Hiatella, 291, 292
arctica, 291, 292
hibernicum, Pisidium, 121-124
hibernus, Arion, 73
Hippeutis, 56, 145
complanatus, 56, 145
Hippodiplosia, 222, 232, 234
foliacea, 232
Hippurites, 288
Hirudinea, 205
hispida, Trichia, 117, 249, 261
Hohenwartiana, 86, 89, 90
moitessieri, 86, 89
Holopoda, 260
Holopodopes, 260
holoserica, Cyclomenia, 204
hopei, Thuridilla, 237
Horatia, 173
hortensis, Cepaea, 261
hungarica, Helicella, 112, 115, 117

hungaricus, Capulus, 227, 231, 232, 234,

240, 241
Hyalinia, 86
guidonii, 86
lybisonis, 86
lucida, 86
notha, scotophila, 86
scotophila nota, 86
hydatis, Haminea, 236
Hydrobia, 112, 173-175, 277, 301
acuta, 277
consociella, 174
gagathinella, 174
grochmalickii, 173
jenkinsi, 301
longaeva, 112
respensis, 173
ventrosa, 174, 277
Hydrobiidae, 145, 173, 175, 278, 301
Hydrobiinae, 175, 278
Hydrozoa, 212, 219
Hyella, 223
caespitosa, 223
Hygromia, 89, 90

cinctella, 89
Hygromiinae, 261, 262
Hypnophila, 85, 88, 90

dohrni, 85, 88

etrusca, 88
hypnorum, Aplexa, 145

Idulia, 228, 230, 231

coronata, 228, 230, 231
igilicus, Oxychilus, 86
iheringi, Chromodoris, 96
illyrica, Chilostoma planospiva, 261
imbricata, Chama, 188
incarnatus, Angulus, 238
incarnatus, Monachoides, 299
inchoata, Acme, 249
incrustans, Lithophyllum, 225
inflata, Lima, 239
Inoceramus, 288

involutus, 288

sulcatus, 288
intermedium, Chilostoma, 261
intermedius, Arion, 249
intermedius, Lepidopleurus, 236, 241
intersecta, Candidula, 261
interstincta, Chrysallida, 238
involutus, Inoceramus, 288
Iphigena, 55, 299

ventricosa, 55, 299
уста, 226
Ischnochiton, 207, 209

magdalenensis, 207
Isocardiidae, 254
Isoetes, 121

lacustris, 121
Isognomon, 80, 83

alata, 80, 83

¿sognomon, 83

radiata, 80
isognomon, Isognomon, 83
Isognomonidae, 83
Isognomostoma, 117

isognomostoma, 117
isognomostoma, Isognomostoma, 117
Isopoda, 271
italica, Diodora, 231, 234, 240

jacobaeus, Pecten, 231, 234, 240
Jaminia, 55, 85, 88, 89
quadridens, 55, 85, 88, 89
Jania, 224, 230
vubens, 224, 230

325

japonica, Heminerita, 279

japonica, Puperita, 279

jenkinsi, Hydrobia, 301

jenkinsi, Potamopyrgus, 145, 277, 301
jenkinsi carinata, Potamopyrgus, 301

Kamptozoa, 193, 212
Kellia, 168
Kelliella, 249
Kelliellidae, 254
kimatula, Yoldia, 207
knorri, Vermicularia, 81
kotulae, Semilimax, 117
krohni, Glossodoris, 93, 94, 96
Kruppomenia, 204
minima, 204
küsteri, Cochlodina, 87, 88

Laciniaria, 299

biplicata, 299
lactea, Arca, 226, 227, 234, 238-241
lactea, Microhedyle, 236, 241
lactea, Turbonilla, 238
lactuca, Ulva, 224
lacustris, Acroloxus, 145
lacustris, Isoetes, 121
laeve, Deroceras, 297
laevis, Callochiton, 220, 226, 234, 240
laevis, Gyraulus, 145
Laguncularia, 79

vacemosa, 19
Lamellibranchiata, 163, 294
Lamellidens, 286

consobrinus, 286

corrianus, 286

marginalis, 286
lamellosa, Haliotis, 227, 240
Lampsilinae, 272
Lampsilis, 272

fasciola, 272

siliquoidaea, 272

ventricosa, 272
lapicida, Helicigona, 249
lapillus, Nucella, 179, 183, 184
lapillus, Purpura, 265
lapillus, Thais, 265, 293
Lartetia, 278
Lasaea, 168
lateralis, Musculus, 81
laugieri, Calliostoma, 230
Laurencia, 224, 230

obtusa, 224

326

Lauria, 56, 89 Lithoglyphus, 173, 175, 278
cylindracea, 56, 89 notatus, 173
layardi, Nerita, 280, 281 Lithophaga, 81, 220, 225-227, 240, 288
leai, Stenotrema, 260 bisulcata, 81
Lecithoepitheliata, 203 lithophaga, 220, 225-227, 240
Leda, 238, 241 lithophaga, Lithophaga, 220, 225-227, 240
fragilis, 238 lithophaga, Petricola, 225-227, 240
legumen, Pharus, 238 Lithophyllum, 224, 225
Lehmannia, 86, 269 incrustans, 225
caprai, 86 тасети$, 225
lenticula, Caracollina, 88 Lithothamnium, 222, 224, 234, 240
leonina, Melibe, 295, 296 Litorella, 121
Lepidopleurus, 227, 236, 240, 241 uniflora, 121
cajetanus, 227, 240, 241 litteratum, Cerithium, 82
cancellatus, 236 Littorina, 80, 82, 219, 220, 223, 224,
intermedius, 236, 241 235, 240
Leptachatina, 260 angulifera, 80, 82
Leucochroa, 55 melanostoma, 82
avigoi, 55 nebulosa, 82
Lichenopora, 227 neritoides, 219, 220, 223, 224, 235,
radiata, 227 240
Lichina, 223 Littorinidae, 82
confinis, 223 Lochea, 73
lignarius, Scaphander, 236 Loligo, 246
lillianae, Lymnaea stagnalis, 101, 102 longaeva, Hydrobia, 112
lilljeborgii, Pisidium, 121-124, 268 Loxosomatidae, 212
Lima, 164, 231, 234, 239, 240, 288 lubrica, Cochlicopa, 249
inflata, 239 Lucapina, 81
lineata, 288 sowerbü, 81
Limacidae, 115, 269, 273 lucida, Hyalinia, 86
Limax, 87, 89, 90, 249, 269, 273, 297 lucidus, Oxychilus, 55
corsicus, 89 Lucinidae, 81, 288
flavus, 87, 273 lusitanica, Patella, 220, 224, 225, 240
valentianus, 297 lusitanicus, Arion, 73-77
limbata, Dendrodoris, 232, 234, 240 lusitanicus nigrescens, Arion, 73
Limidae, 222 luteocincta papillata, Diaphorodoris, 93, 98
Limifossor, 204 luteorosea, Chromodoris, 96
Limifossoridae, 204 luteorosea, Glossodoris, 93, 94, 96
limophilus, Gyraulus albus, 56 lutescens, Doris, 96, 97
Limopsis, 271 luzonica, Paphia, 83
dalli, pelagica, 271 lybisonis, Hyalinia, 86
pelagica, 271 Lymnaea, 28, 39, 42, 54, 89, 101, 102,
pelagica dalli, 271 105, 106, 127, 128, 133, 145, 148,
pelagica pelagica, 271 149, 263, 277
lineata, Coryphella, 230, 231 auricularia, 145
lineata, Lima, 288 catascopium nasoni, 263
Lineus, 208 catascopium preblei, 263
ruber, 208 glabra, 145
Linga, 288 glutinosa, 145
columbella, 288 lillianae, stagnalis, 101, 102

liquefaciens, Aeromonas, 43 nasoni, catascopium, 263

natalensis, 39

palustris, 145, 227

peregra, 54, 89, 145, 149, 277
preblei, catascopium, 263
sanctaemariae, stagnalis, 263

stagnalis, 42, 101, 102, 105, 106, 145

stagnalis lillianae, 101, 102
stagnalis sanctaemariae, 263

truncatula, 89, 127, 128, 133, 145, 148

Lymnaeidae, 42, 145, 263
Lyngbyia, 224, 227
confervoides, 224

macedonica, Sadleriana, 173
macerophylla, Chama, 80
Macoma, 238

tenuis, 238
Macroptychia, 258

africana, 258
Mactra, 238, 241, 245

corallina, 245

stultorum, 238
maculata, Pinctada, 188
maculatus, Rhacophorus, 286, 287
maculosa, Pisania, 220, 225, 230, 240
maculosus, Geomalacus, 249
magdalenensis, Ischnochiton, 207
magnus, Gibbula, 293
major, Phenacolimax, 269
Malacolimax, 269
Malletia, 271

cuneata, 271
mamillata, Phallusia, 231, 232
mangle, Rhiziphora, 79, 80, 82
manii, Teredo, 83

mansoni, Schistosoma, 25, 31, 32, 40, 43

Margaritana, 67
margaritifera, 67
margaritifera, Margaritana, 67
marginalis, Lamellidens, 286
marginella, Avion rufus atra, 73, 74
marina, Zostera, 236
Marisa, 40
cornuarietis, 40
Marmorana, 85, 88, 90
argentarolae forsythi, 88
forsythi, argentarolae, 88
marmoratus, Musculus, 225, 228, 231,
239, 240
Martesia, 167-170
martineanus, Murex, 82
massa, Mycale, 226

Mastigocleus, 223

testarum, 223
Mastus, 117

bielzi, 117
maxima, Tridacna, 188, 189
Mecynodon, 288

carinatus, 288
Mediappendix, 289
mediterranea, Acetabularia, 224, 227
mediterranea, Corallina, 224, 225
mediterranea, Cystoseiva, 224
Meekella, 288
Megalodontidae, 288
Megalodus, 288
meisneriana, Cochlodina, 87, 88
Melampus, 81, 82

bidentatus, 81, 82

coffeus, 81, 82
Melanella, 238, 241

arcuata, 238
Melania, 113

tuberculata, 113
melanostictus, Bufo, 286
melanostoma, Littorina, 82
Melibe, 295, 296

leonina, 295, 296
Melobesia, 227
Melongena, 81, 82

corona, 81

melongena, 81, 82

pugilina, 82
melongena, Melongena, 81, 82
Melongenidae, 82
Membranipora, 230
mentula, Ascidia, 231
mercatoria, Columbella, 82
Mercenaria, 275, 276

mercenaria, 215, 276
mercenaria, Mercenaria, 275, 276
mercenaria, Venus, 125
Meretrix, 83

meretrix, 83
meretrix, Meretrix, 83
mevidionale, Propeamussium, 271
Mesarion, 73
Mesodesma, 201
Mesodontopsis, 87

chaixii, 87
Mesogastropoda, 279

messinensis, Glossodoris, 93, 95, 96,

Mesurethra, 289
Metachaetoderma, 204

327

328

Metachatina, 256
metidjensis, Planorbarius, 25, 26, 55
Metorponothus, 43
pruinosus, 43
Microhedyle, 236, 241
glandulifera, 236, 241
lactea, 236, 241
milaschewitchii, 236, 241
Micromelania, 173, 176
filocincta, 176
prespensis, 173
Micromelaniidae, 176
Micromelaniinae, 173, 175, 176
micropleuros, Pleuropunctum, 89
Micropyrgula, 176
Middendorfia, 220, 224, 225, 240
caprearum, 220, 224, 225, 240
Milacidae, 269
milaschewitchii, Microhedyle, 236, 241
Milax, 87, 90
nigricans, 87
sowerby, 87
milium, Pisidium, 268
millepunctata, Natica, 236, 241
mimetica, Bosellia, 220, 226, 237, 240
minima, Batillaria, 81, 82
minima, Kruppomenia, 204
minimum, Carychium, 115, 117
minimus, Brachydontes, 220, 224, 225,
231, 238, 240
Mitra, 230
Mitraria, 209, 210
modesta, Vertigo, 297
Modiolus, 80, 83, 201, 234, 238, 241
americanus, 80, 83
barbatus, 234, 238, 241
Modulus, 82
modulus, 82
modulus, Modulus, 82
moitessieri, Hohenwartiana, 86, 89
Monacha, 55
cartusiana, 55
Monacheae, 262
Monachoides, 299
incarnatus, 299
Monodonta, 220, 224, 225, 240
turbinata, 220, 224, 225, 240
Monotidae, 288
Monotis, 288
Montacuta, 168
montana, Trichia striolata, 261, 262
Moria, 278

morio, Pugilina, 81
moulinsiana, Vertigo, 115
Mucrospirifer, 288
reidfordi, 288
Murex, 80, 82, 207, 220, 226, 230, 231,
234, 238, 240, 241
blainvillei, 220
brandaris, 238, 241
brevifrons, 80, 82
martineanus, 82
ramosus, 207
trunculus, 226, 230, 231, 234, 240, 241
muricatum, Trachycardium, 81
muricatus, Tectarius, 82
Muricidae, 82, 226, 227, 240
Muricidea, 226, 227, 230, 240
blainvillei, 226, 227, 230, 240
muscorum, Pupilla, 113, 115, 117, 249
Musculus, 81, 222, 225, 228, 231, 239,
240
lateralis, 81
marmoratus, 225, 228, 231, 239, 240
mutabilis, Nassa, 236, 241
Mya, 243
Mycale, 226
massa, 226
Myoconcha, 288
Myonera, 271
undata, 271
Myophoria, 288
myosotis, Alexia, 224, 240
Myriophyllum, 121
Myriozoum, 222, 234
Mytella, 80
guyannensis, 80
Mytilidae, 83, 169
Mytilus, 154, 155, 159, 164, 168, 169,
224-226, 240
galloprovincialis, 224-226, 240

патай, Doris, 96

nasoni, Lymnaea catascopium, 263

Nassa, 207, 226, 236, 238, 241
mutabilis, 236, 241
neritea, 236
reticulata, 226

Nassidae, 226

nasutus, Bulinus, 35

Nata, 256

natalensis, Bulinus, 37, 38

natalensis, Lymnaea, 39

Natalina, 256

Natica, 236, 238, 241, 247
millepunctata, 236, 241
Naticidae, 204
nautiliforme, Drepanostoma, 267
Nautilus, 206, 209
neapolitana, Spurilla, 230, 231
nebulosa, Littorina, 82
Nemalion, 224
helminthoides, 224
Nematomenia, 207, 209
banyulensis, 207, 209
Nematomorpha, 213
Nemertini, 205, 208, 210, 214
nemoralis, Cepaea, 55
Neofossarulus, 173
stankovici, 173
Neomenia, 207, 208, 210
carinata, 207, 208, 210
Neomeniida, 193
Neopilina, 193, 198-201, 206, 214
Nerita, 82, 279-281
birmanica, 82
chamaeleon, 280, 281
dombeyi, 280, 281
layardi, 280, 281
peloronta, 82
plicata, 280, 281
vumphii, 280, 281
tessellata, 82
versicolor, 82
Neritacea, 279
neritea, Nassa, 236
Neritidae, 82, 279
Neritina, 47-51, 81, 82, 279, 281
crepidularia, 281
glabrata, 47-51
oualaniensis, 279-281
retifera, 280, 281
violacea, 279
virginea, 81, 82
neritoides, Littorina, 219, 220, 223, 224,
235, 240
Nesovitrea, 115, 249, 297, 299
binneyana, 297
electrina, 297
hammonis, 115, 249, 297
petronella, 249, 297, 299
nigra, Ascidia, 81
nigrescens, Arion lusitanicus, 73
nigricans, Milax, 87
Nitella, 121
nitida, Avicennia, “9

329

nitidula, Aegopinella, 269
nitidum, Pisidium, 122, 124, 268
nitidus, Zonitoides, 260, 269
noae, Arca, 232, 234
nobilis, Pinna, 238, 241
nobrei, Avion, 73
nodocostata, Grammysia, 288
notabilis, Anadara, 80, 83
notatus, Lithoglyphus, 173
notha, Hyalinia scotophila, 86
Notoneuralia, 213
Nucella, 179, 183, 184
lapillus, 179, 183, 184
nucleus, Nucula, 231, 234, 238, 240
Nucula, 168, 201, 207, 208, 210, 231,
234, 238, 240, 241
nucleus, 231, 234, 238, 240
proxima, 207, 208
Nuculacea, 163
Nuculana, 168, 201
Nudibranchia, 282, 295
nudus, Sipunculus, 208, 209

oblonga, Succinea, 115, 117, 249
obscura, Ena, 56
obscuratus, Oxychilus, 86
obtusa, Cerithidea, 82
obtusa, Laurencia, 224
obtusus, Cylindrus, 249, 251
obvia, Helicella, 303
obvoluta, Helicodonta, 267
occultata, Chilostoma planospiva, 85, 87
occultata, Helicogona planospiva, 85, 87
oceanica, Posidonia, 236
ochridana, Valvata, 173
Ochridopyrgula, 176
Octopus, 246, 247
dofleini, 247
octoradiata, Hemitoma, 81
officinalis, Sepia, 245, 246
oglasicola, Alzonula, 86
oglasicola, Oxychilus, 86
ohridana, Gocea, 173
Ohrigocea, 173
olivaceus, Chiton, 224, 225, 227, 230,
231, 240
Olivella, 290
biplicata, 290
olsenae, Spondylus, 288
Omalonyx, 259
Oncidiidae, 282
onzariensis, Valvata sincera, 263

330

Oopelta, 256, 258
Oopeltinae, 256
Opeas, 260
Ophiocephalus, 286, 287
gachua, 286
punctatus, 286
striatus, 286
Opisthobranchia, 93, 217, 222, 230, 236,
238, 241, 253, 282, 295
oppressus, Oxychilus, 86
orbiculata, Arca, 271
ornatus, Cyrtolites, 201
oysinii, Doris, 96
Orthurethra, 260, 289
Ostrea, 80, 81, 164, 220, 224-227, 240
edulis, 220, 224-227, 240
frons, 80
permollis, 81
Ostreidae, 83, 164
oualaniensis, Neritina, 279-281
ovata, Abra, 277
ovula, Tralia, 82
Oxychilus, 55, 56, 86, 87, 89, 90, 117,
269, 273, 274
alliarius, 273, 274
argentaricus, 86
cellarius, 269, 273
depressus, 117
draparnaudi, 269
gorgonianus, 86
igilicus, 86
lucidus, 55
obscuratus, 86
oglasicola, 86
oppressus, 86
pazi, 56
pilula, 86
Oxyloma, 259

Padina, 224, 230

pavonia, 224, 230
pagenstecheri, Spirorbis, 227
Paladilhia, 278
Palaeosolen, 288
pallens, Doris, 96
palustris, Galba, 42
palustris, Lymnaea, 145, 277
panicea, Halichondria, 225
panormitanus, Dentalium, 238, 241
Papaver, 249

relictum, 249
Paphia, 83

luzonica, 83

papillaris, Papillifera, 88
papillata, Diaphorodoris luteocincta, 93
98
Papillifeva, 88-90
papillaris, 88
solida, 89
papillifera, Pseudovermis, 236, 241
parasitica, Crassostrea, 83
Parazoanthus, 226
axinellae, 226
parcedentata, Vertigo, 249
Parenchymella, 212
Parreysia, 286
corrugata, 286
rugosa, 286
parthenopeia, Doris, 96
partschi, Cardita, 288
pasinii, Doris, 96
Patella, 207, 209, 210, 220, 224, 225, 240,
244, 245, 247
coerulea, 220, 224, 225, 240
lusitanica, 220, 224, 225, 240
vulgata, 244
patelliformis, Anomia, 288
patula, Purpura, 82
patulum, Cerithium, 82
paucicostatum, Cardium, 238, 241
pavonia, Padina, 224, 230
pazi, Oxychilus, 56
Pecten, 157, 168, 231, 234, 240, 288
jacobaeus, 231, 234, 240
Pectinacea, 222
Pectinidae, 247, 272, 288
Pegea, 90
carnea, 90
pelagica, Limopsis, 271
pelagica, Limopsis pelagica, 271
pelagica dalli, Limopsis, 271
pelagica pelagica, Limopsis, 271
Pelagosphaera, 212
Pelecypoda, 83, 163, 272
pellucida, Cladophora, 274
pellucida, Vitrina, 249, 269
peloronta, Метйа, 82
Peltodoris, 220, 226, 227, 237, 240
atromaculata, 220, 226, 227, 237, 240
Pentacoela, 213
peregra, Lymnaea, 54, 89, 145, 149, 277
peregra, Radix, 42, 54, 55, 89
peregrina, Hervia, 230, 231
perezi, Anisus, 56
Perforatella, 113, 115, 117
bidentata, 113, 115

dibothryon, 117
perla, Poromya, 271
permollis, Ostrea, 81
personatum, Pisidium, 268
pes pelecani, Aporrhais, 231, 232, 234,
235, 238, 240, 241
petiolata, Udotea, 228
Petricola, 168, 225-227, 240
lithophaga, 225-227, 240
petronella, Nesovitrea, 249, 297, 299
Petrosia, 220, 226, 227, 240
ficiformis, 220, 226, 227, 240
Peyssonnelia, 220, 226, 230, 240
squamaria, 220, 226, 230, 240
pfeifferi, Biomphalaria, 35, 43
Phagocytella, 212
Phallusia, 231, 232
mamillata, 231, 232
Pharus, 238
legumen, 238
Phenacolimax, 117, 269
annularis, 117
major, 269
Philine, 234, 236, 241
aperta, 234, 236, 241
Philinoglossa, 236, 241
helgolandica, 236, 241
philippi, Granopupa, 85, 88
philippi, Pupestrella, 85, 88
Pholadidae, 164, 167, 168, 170
Phoronidea, 212, 213
Phragmites, 268
Physa, 44, 54, 55, 145, 277
acuta, 54, 55, 277
fontinalis, 145
Physidae, 145
Physopsis, 37
picta, Doris, 96
pictorum, Unio, 65
Pilidae, 263
Pilina, 201
pilosa, Glycymeris, 288
pilula, Oxychilus, 86
Pinctada, 80, 188
maculata, 188
radiata, 80
Pinna, 165, 168, 238, 241, 288
nobilis, 238, 241
pirainii, Doris, 96
pisana, Euparypha, 55
pisana, Theba, 89, 261
Pisania, 220, 225, 230, 240
maculosa, 220, 225, 230, 240

331

piscinalis, Valvata, 145
Pisidium, 121-125, 268
casertanum, 268
conventus, 123, 124, 268
hibernicum, 121-124
lilljeborgii, 121-124, 268
milium, 268
nitidum, 122-124, 268
personatum, 268
subtruncatum, 268
Pitaria, 231, 234, 238, 240
chione, 231, 234, 240
Placophora, 191, 193, 195, 198, 199, 201,
207, 209, 210, 212, 214, 217, 224-
227, 230, 231, 234, 236, 238, 240,
241
Placuna, 288
planatus, Angulus, 238
Planispiva, 260
fallaciosa, 260
Planorbarius, 25, 26, 55, 145
corneus, 145
metidjensis, 25, 26, 55
Planorbidae, 35, 43, 54, 145, 263
Planorbinae, 26
Planorbis, 145
carinatus, 145
planorbis, 145
planorbis, Planorbis, 145
planospira illyrica, Chilostoma, 261
planospira occultata, Chilostoma, 85, 87
planospira occultata, Helicigona, 85, 87
Plantago, 249
Plathelminthes, 203, 210, 214
Pleurobranchidae, 234
Pleuroceridae, 263
Pleuropunctum, 88, 89
micropleuros, 89
plicata, Nerita, 280, 281
plioauriculata, Polygyra, 267
pluma, Aglaophenia, 225
Plumularia, 226
Pododesmus, 80, 83
vudis, 80, 83
Pogonophora, 213
polita, Acicula, 117
Polycera, 234, 241
quadrilineata, 234, 241
Polycladida, 203
Polygordius, 208
Polygyra, 267
plioauriculata, 267
Polygyracea, 260

332

polymorpha, Dreissena, 207
Polynices, 236, 238, 241

guillemini, 236
Polysiphonia, 224

sertularoides, 224
pomatia, Helix, 135-139, 153, 261, 303
Pomatias, 87, 90, 117

elegans, 87, 117
Porifera, 222, 230, 231
Poromya, 271

perla, 271

tornata, 271
porroi, Cochlodina, 87, 88
Posidonia, 222, 236, 241, 288

oceanica, 236
Potamididae, 82, 83
Potamogeton, 268
Potamopyrgus, 145, 277, 301

cavinata, jenkinsi, 301

jenkinsi, 145, 277, 301

jenkinsi carinata, 301
Potentilla, 249
preblei, Lymnaea catascopium, 263
prespensis, Diana, 174, 176
prespensis, Hydrobia, 173
prespensis, Micromelania, 173
Prestonella, 256
prevostianus, Theodoxus, 113
Prochaetoderma, 204, 206

californicum, 206
Productacea, 288
profuga, Cernuella, 85
profundorum, Abra, 271
Prolecithophora, 203
Propeamussium, 271

meridionale, 271
Proseriata, 203
Prosobranchia, 201, 217, 230, 231, 236,

238, 241, 284, 293, 294
Protobranchia, 163, 164, 191, 201, 207-
210, 214, 238, 272

Protodrepanostoma, 267
Protostomia, 205, 213
proxima, Nucula, 207, 208
pruinosus, Metopornothus, 43
Psammobia, 238

depressa, 238
Psammobiidae, 164
Pseudamnicola, 173-175, 277

anatina, 277

compacta, 277

consociella, 173

curta, 174

Pseudlithophyllum, 225, 226, 240

expansum, 225, 226
Pseudohoratia, 173
Pseudolamellibranchia, 165
Pseudomonadaceae, 43
pseudosubstriata, Vertigo, 117
Pseudovermis, 236, 241

papillifera, 236, 241

schulzi, 236, 241
Pteria, 80

colymbus, 80
Pterobranchia, 213
Pugilina, 81

morio, 81
pugilina, Melongena, 82
pulchella, Vallonia, 249, 260
pulchella, Valvata, 117
pulcherrima, Doris, 96
pulchra, Embletonia, 236, 241
pulla, Tricolia, 230, 293
pullastra, Venerupis, 275

Pulmonata, 43, 54, 73, 101, 217, 262,

273, 274, 282
pumila, Clausilia, 117, 249, 297
pumila, Emarginula, 81
punctata, Aplysia, 253
punctatus, Ophiocephalus, 286
Punctum, 249

pygmaeum, 249
Pupa, 56
gratiosa, 56
Puperita, 279
japonica, 279
Pupilla, 113, 115, 117, 249
muscorum, 113, 115, 117, 249
sterri, 115, 117
triplicata, 117
Pupillacea, 260
Purpura, 82, 265
lapillus, 265
patula, 82
purpurea, Glossodoris, 95, 96
Pusia, 230
tricolor, 230
putris, Succinea, 249
pygmaea, Vertigo, 113, 249
bygmaeum, Punctum, 249
pyramidata, Trochoidea, 86
Pyramidula, 83
vupestris, 85
pyrenaica, Pyrgula, 176

Pyrgohydrobia, 173
grochmalicki, 173

Pyrgophysa, 37

Pyrgula, 173, 175, 176
annulata, 175, 176
darieuxi, 176
pyrenaica, 176
sturanyi, 173

Pyrgulinae, 173, 175, 176

quadrasi, Helix, 267

quadrasi, Trissexodon, 267
quadridens, Jaminia, 55, 85, 88, 89
quadrilineata, Polycera, 234, 241
Quickella, 289

Quickia, 259

racemosa, Laguncularia, “9
racemus, Lithophyllum, 225
radiata, Isognomon, 80
radiata, Lichenopora, 227
radiata, Pinctada, 80
Radix, 42, 54, 55, 89

auricularia, 54, 55

peregra, 42, 54, 55, 89
ramosus, Murex, 207
Rana, 286

hexadactyla, 286
Rathousiidae, 282
recurvus, Brachidontes, 80
veidfordi, Mucrospirifer, 288
relictum, Papaver, 249
velictus, Gyraulus, 173
reniformis, Chondrosia, 226
requieni, Unio, 65
Retama, 54

sphaerocarpa, 54
Retepora, 222, 234
reticulata, Nassa, 226

reticulatum, Bittium, 228, 230, 231, 234,

238, 240, 241

reticulatus, Agriolimax, 179-182, 273

retifera, Neritina, 280, 281
retropictus, Clithon, 279
Retusa, 236
Rhabdocoela, 203
Rhacophorus, 286, 287
maculatus, 286, 287
rhiziphorae, Crassostrea, 80, 83
Rhizophora, 79-82
mangle, 79, 80, 82

Rhodope, 282
veranii, 282
vhomboides, Venerupis, 275
Rhytididae, 256-258
Richthofenia, 288
riisei, Tropicorbis, 40
Rissoa, 228, 230, 231, 235, 240
variabilis, 228, 230, 231, 235, 240
Rissoacea, 230, 238
Rissoidae, 222, 241
rivieriana, Truncatellina, 55
Rivulina, 125
robici, Bythinella, 173
robici, Sadleriana, 174
rohlfsi, Bulinus truncatus, 38
ronnebyensis, Vertigo, 297
rosea, Aenigma, 83
rotundatus, Discus, 249
Roudairea, 288
royalense, Helisoma anceps, 262
vubens, Чата, 224, 230
ruber, Lineus, 208
rubiginosus, Arion, 73
rubrum, Gasteropteron, 207
ruderatus, Discus, 299
vudis, Pododesmus, 80, 83
rufus, Arion, 73, 74, 76, 303
rufus, Arion ater, 73
rufus atra, Arion, 73
rufus (та aterrima, Arion, 73
rufus ата marginella, Arion, 73, 74
rufus atra sulcata, Arion, 73, 74
rugosa, Astraea, 231, 234, 240, 241
rugosa, Parreysia, 286
vumelica, Helix, 135
Rumina, 55
decollata, 55
vumphii, Nerita, 280, 281
Runcina, 238, 241
coronata, 238, 241

333

rupestre, Cerithium, 225, 234, 238, 240,

241
Rupestrella, 85, 88
philippi, 85, 88
vupestris, Pyramidula, 85

rustica, Columbella, 225, 230, 231, 238,

240, 241

Sacoglossa, 226

Sadleriana, 173-175
fluminensis, 174
macedonica, 173

334

robici, 174

virescens, 173
Saganoa, 278
sancta, Cochlodina, 88
sanctaemariae, Lymnaea stagnalis, 263
sanguinea, Schizoporella, 225
sarda, Cochlodina, 88
Sargassum, 224, 230
scacchiana, Doris, 97
scalaris, Cacospongia, 225, 226
Scaphander, 236

lignarius, 236

Scaphopoda, 191, 201, 203-205, 207, 209,

210, 214, 236, 238, 241
Schistosoma, 25-27, 29-33, 37, 40, 43
europeense, haematobium, 26
haematobium, 25-27, 29-33, 37
haematobium europeense, 26
mansoni, 25, 31, 32, 40, 43
Schizoporella, 225
sanguinea, 225
schlikumi, Diana, 176
schultzii, Doris, 97
schulzi, Pseudovermis, 236, 241
Scolecida, 282
scotophila notha, Hyalinia, 86
Scrobicularia, 243
Scrupodellaria, 230
Sculptaria, 256
Scutopus, 201, 204
ventrolineatus, 201
scutulum, Testacella, 86
Scyphozoa, 212
Segmentina, 145
Semelidae, 164
Semilimax, 117
kotulae, 117
Sepia, 245, 246
officinalis, 245, 246
Septaria, 279-281
compressa, 280, 281
tessellata, 279-281
Septibranchia, 272
sepultus, Zonitoides, 113
sericinus, Bulinus, 37
serotina, Gastrocopta, 113, 115
sertularoides, Polysiphonia, 224
Sheldonia, 256
sibivica, Valvata, 145
Sidonia, 282
elegans, 282
Sigmurethra, 260, 289

siliqua, Ensis, 238
siliquoidea, Lampsilis, 272
silvaticus, Arion, 297
sincera ontariensis, Valvata, 263
sinensis, Calyptraea, 231, 234, 240, 241
Sinuitopsis, 201
acultilira, 201
similis, Arca, 165, 168
simplex, Columella, 297
simplex, Digenea, 228
Siphonaria, 81
Sipunculida, 203, 205, 208, 210, 212, 214
Sipunculus, 208-210, 212
nudus, 208, 209
Solecurtidae, 164
Solen, 232, 236, 238, 241, 288
vagina, 232, 238, 241
Solenocurtus, 238
strigillatus, 238
Solenogastres, 191-193, 195, 196, 198-
200, 203, 204, 207-210, 212, 214
Soleolifera, 282, 284
solida, Papillifera, 89
Soósia, 117
diodonta, 117
sophiae, Cochlodina, 88
sowerbii, Lucapina, 81
sowerby, Milax, 87
Spelaeodiscinae, 267
speciosa, Tricolia, 230
Sphaeriidae, 121, 263, 268
Sphaerium, 125
sphaerocarpa, Retama, 54
Sphagnum, 149
spicata, Cystoseira, 227, 230
spiculifera, Hedylopsis, 236, 241
spirorbis, Anisus, 55, 145
Spirorbis, 227
pagenstecheri, 227
splendida, Thuridella, 230, 231, 240
Spondylidae, 164, 288
Spondylus, 288
olsenae, 288
Spongiaria, 219
Spurilla, 230, 231
neapolitana, 230, 231
squamaria, Peyssonnelia, 220, 226, 230
240
stagnalis lillianae, Lymnaea, 101, 102
stagnalis, Lymnaea, 42, 101, 102, 105,
106, 145
stagnalis sanctaemariae, Lymnaea, 263

stagnalis, Succinea, 55
stankovici, Neofossarulus, 173
Stankovicia, 176
baicaliifovmis, 176
stellatus, Chthamalus, 223
stellatus, Chthamalus stellatus, 223
Stenothecoida, 203
Stenothecoides, 203
Stenotrema, 260
leai, 260
sterri, Pupilla, 115, 117
Streptaxidae, 256, 257
Streptoneura, 279
striata, Bullaria, 236, 241
striata, Helicella, 112
striatula, Venus, 275, 276
striatus, Cantharidus, 230, 238, 241
striatus, Ophiocephalus, 286
strigillatus, Solenocurtus, 238
striolata, Trichia, 113
striolata danubialis, Trichia, 261
striolata montana, Trichia, 261, 262
Strombiformis, 238
subulata, 238
stultorum, Mactra, 238
sturanyi, Deroceras, 297
sturanyi, Pyrgula, 173
Stylommatophora, 259, 260, 282, 289
subconstrictus, Helix, 267
subcylindrica, Truncatella, 85, 87, 224,
240
subfuscus, Arion, 73, 74, 76, 249
subglobosa, Congeria, 288
subpulchella, Vallonia, 112
substriata, Vertigo, 249
subtruncatum, Pisidium, 268
subulata, Strombiformis, 238
Subulinidae, 256, 257
Succinea, 55, 115, 117, 249, 259, 289,
297
antiqua, 249
oblonga, 115, 117, 249
putris, 249
stagnalis, 55
Succineacea, 260
Succineidae, 259, 260, 289
Succineinae, 289
sudanica tanganyicensis, Biomphalaria,
35
sulcata, Arion rufus atra, 73, 74
sulcata, Terebralia, 82
Sulcatopinna, 288

335

sulcatus, Arion, 76
sulcatus, Inoceramus, 288
Symptonata, 286
systoma, Cacopus, 287

Tacheocampylaea, 87, 90

chaixii, 87

elata, 87

tacheoides, 87
tacheoides, Tacheocampylaea, 87
tanganyicensis, Biomphalaria sudanica, 35
Taraxacum, 249

dovrense, 249
Tarebia, 40

granifera, 40
tataénsis, Belgrandia, 117
Taxodonta, 163
Tectarius, 82

muricatus, 82
Telescopium, 82

telescopium, 82
telescopium, Telescopium, 82
telleri, Eumorphotis, 288
Tellina, 167, 168, 170, 232, 236, 238,

239, 241

distorta, 232, 236, 239, 241
Tellinacea, 164, 167, 170
Tellinidae, 164, 170
tenellus, Arion, 73
tenera, Doris, 96
Tentaculata, 213
tentaculata, Bithynia, 277
tentaculata thermalis, Bithynia, 113
tenuilabris, Vallonia, 113, 115, 117, 249
tenuis, Macoma, 238
Terebralia, 82

sulcata, 82
Teredinidae, 83, 164, 168
Teredo, 81, 83, 168, 169

manii, 83
Tergipes, 236, 241

despectus, 236, 241
tesselata, Septaria, 279-281
tesselata, Nerita, 82
Testacella, 86

scutulum, 86
testarum, Mastigocleus, 223
Tethymelibidae, 295
Thais, 265, 293, 294

lapillus, 265, 293
Theba, 89, 261

pisana, 89, 261

336

Theodoxus, 113, 279
fluviatilis, 279
prevostianus, 113
thermalis, Bithynia tentaculata, 113
thiesseana, Diana, 173, 174, 176
Thuridilla, 230, 231, 237, 240
hopei, 237
splendida, 230, 231, 240
Thymus, 54
togata, Gari, 83
tornata, Poromya, 271
tornatilis, Acteon, 232, 236, 241
Toxoglossa, 226
Trachycardium, 81
muricatum, 81
Trachycystis, 256
Trachyochridia, 176
Tralia, 82
ovula, 82
Trichia, 113, 117, 249, 261, 262
danubialis, striolata, 261
hispida, 117, 249, 261
montana, striolata, 261, 262
striolata, 113
striolata danubialis, 261
striolata montana, 261, 262
Tricladida, 203
Tricolia, 230, 293, 294
pulla, 230, 293
speciosa, 230
tricolor, Glossodoris, 93, 95, 96, 98
tricolor, Pusia, 230
Tridacna, 168, 188, 189
maxima, 188, 189
Tridacnidae, 288
tridens, Chondrula, 117
Trigonephrus, 256
Trigonia, 163, 288
trilineata, Chromodoris, 96
Trinchesia, 230, 231
foliata, 230, 231
triplicata, Pupilla, 117
triplicata, Turritella, 238, 241
Trissexodon, 267
constrictus, 267
quadrasi, 267
Tritonalia, 226-228, 230, 231, 240
aciculata, 226, 228, 230, 231, 240
edwardsi, 226, 227, 230, 240
Trivia, 232, 234-236, 241
adriatica, 232, 235, 236, 241
Trochidae, 222, 230, 238, 240

Trochoidea, 86, 88, 90
pyramidata, 86
trochoides, 88
trochoides, Trochoidea, 88
Trochomorpha, 86
Tropicorbis, 40
riisei, 40
tropicus, Bulinus, 37-39
tropicus, Bulinus tropicus, 38
tropicus alluaudi, Bulinus, 38
tropicus tropicus, Bulinus, 38
Truncatella, 85, 87, 224, 240
subcylindrica, 85, 87, 224, 240
Truncatellina, 55, 112, 115, 249
britannica, 249
claustralis, 115
cylindrica, 112, 115, 249
rivieriana, 55
Truncatellinae, 176
truncatula, Galba, 42, 55, 89
truncatula, Lymnaea, 89, 127, 128, 133, 1
145, 148
truncatus, Bulinus, 25, 26, 28, 29, 31-33,
37, 38
truncatus, Bulinus truncatus, 38
truncatus rohlfsi, Bulinus, 38
truncatus truncatus, Bulinus, 38
trunculus, Donax, 238
trunculus, Murex, 226, 230, 231, 234,
240, 241
Tryblidiacea, 191, 193, 200, 201, 212-214
Tryblidium, 201
tuberculata, Archidoris, 232, 234, 236,
237, 240, 241
tuberculata, Haliotis, 230
tuberculata, Melania, 113
tuberculatum, Cardium, 238
Tulbaghinia, 256
tulipa, Fasciolaria, 82
tuna, Halimeda, 220, 226, 228, 230, 240
Turbellaria, 209, 210, 214
turbinata, Monodonta, 220, 224, 225, 240
Turbinidae, 293
Turbo, 293
Turbonilla, 238, 241
lactea, 238
Turritella, 232, 238, 241
communis, 232, 238, 241
triplicata, 238, 241
Turtonia, 168, 254

Udotea, 228

petiolata, 228
ugandae, Bulinus, 35
Ulva, 224, 225

lactuca, 224
umbrosa, Zenobiella, 261
undata, Grammysia, 288
undata, Myonera, 271
undatus, Cyclopecten, 271
uniflora, Litorella, 121
Unio; 65, 66, 68, 71, 112

pictorum, 65

requieni, 65
Unionidae, 263, 272
Urocyclidae, 256, 257

vagina, Solen, 232, 238, 241
Vaginulidae, 282
Vaginulus, 284, 285
borellianus, 284
valenciennesi, Glossodoris, 93, 95-98
valentianus, Limax, 297
Vallonia, 55, 112, 113, 115, 117, 249,
260, 297
costata, 55, 112, 115, 117, 249
enniensis, 115, 117
pulchella, 249, 260
subpulchella, 112
tenuilabris, 113, 115, 117, 249
Valvata, 112, 117, 145, 173, 263
cristata, 145
ochridana, 173
ontariensis, sincera, 263
piscinalis, 145
pulchella, 117
sibirica, 145
sincera ontariensis, 263
Valvatidae, 145
varia, Gibbula, 230, 238, 241
variabile, Cerithium, 81
variabilis, Rissoa, 228, 230, 231, 235,
240
Veneracea, 222
Veneridae, 81, 83, 168, 231, 234, 254,
215
Venerupis, 238, 254, 275, 276
aurea, 275
decussata, 275, 276
pullastra, 275
rhomboides, 275
ventricosa, Iphigena, 55, 299
ventricosa, Arca, 188, 189
ventricosa, Lampsilis, 272

337

ventricosus, Conus, 225, 226, 228, 230,
231, 238, 240, 241
Ventriplicida, 193
ventrolineatus, Scutopus, 201
ventrosa, Hydrobia, 174, 277
venulosa, Doris, 96
Venus, 125, 231, 234, 238, 240, 241, 275,
276
casina, 238, 241
gallina, 238
mercenaria, 125
striatula, 275, 276
verrucosa, 231, 234, 240, 275, 276
veranii, Rhodope, 282
vermeta, Catinella, 260
Vermetus, 226, 227, 231, 234, 240
Vermicularia, 81
knorri, 81
vermiculata, Eobania, 55
vermilionense, Helisoma corpulentum,
263
Veronicella, 264
aberrans, 264
ameghini, 264
anguistipes, 264
Veronicellidae, 257
verrucosa, Epimenia, 204, 207, 209
verrucosa, Venus, 231, 234, 240, 275,
276
versicolor, Nerita, 82
verticillus, Aegopis, 117
Vertigo, 112, 113, 115, 117, 249, 297,
299
antivertigo, 115, 117, 249
artica, 297, 299
callosa, 112
genesii, 297, 299
geyeri, 297
modesta, 297
moulinsiana, 115
parcedentata, 249
pseudosubstriata, 117
pygmaea, 113, 249
ronnebyensis, 297
substriata, 249
Vesicomya, 254
Vesicomyidae, 254
Vidalia, 222, 231, 232, 234, 240, 241
volubilis, 222, 231, 232, 234, 240, 241
villae, Doris, 96
villafranca, Doris, 96
villafranca, Chromodoris, 96

338

violacea, Dostia, 279
violacea, Neritina, 279
virescens, Arion, 73
virescens, Sadleriana, 173
virgata, Cernuella, 55
virginea, Ascidia, 231
virginea, Neritina, 81, 82
virginica, Crassostrea, 80

viridis, Elysia, 228, 230, 231, 238, 240,

241
Vitrea, 85, 87, 90, 297
contracta, 85, 87
crystallina, 85, 87
diaphana, 87
Vitreinae, 269
Vitrina, 117, 249, 269
bielzi, 117
pellucida, 249, 269
Vitrinidae, 269
Vitrinobrachium, 269
breve, 269
Viviparidae, 145, 263
Viviparus, 112, 145, 213, 284, 293
ater, 284
böckhi, 112
viviparus, 145, 293
viviparus, Viviparus, 145, 293
volubilis, Vidalia, 222, 231, 232, 234,
240, 241
vulgare, Dentalium, 236, 241
vulgata, Patella, 244

vulgatum, Cerithium, 231, 234, 240, 241

weberi, Dorymenia, 204

whiteavesi, Helisoma corpulentum, 263

Xerocerastus, 256
Xeromagna, 55
arigoi, 55
Xerotricha, 55, 88
apicina, 88
conspurcata, 55, 88
Xylophaga, 168, 169

Yoldia, 201, 207, 210
kimatula, 207

zebra, Cypraea, 82
Zenobiella, 261
umbrosa, 261
zilchi, Chilopyrgula, 176
zizyphinus, Calliostoma, 231
Zonitacea, 260, 269
Zonitidae, 86, 115, 269, 274, 289
Zonitinae, 269
Zonitoides, 113, 249, 260, 269, 297
arboreus, 297
excavatus, 249, 269
nitidus, 260, 269
sepultus, 113
Zostera, 222, 236, 241
marina, 236

tar - ИМ 236,2

vor 9 NO.2 mus. com ZOOL DECEMBER 1969
LIBRARY
: oct 7 1970
\ N
7 HARVARD
à 5 RSITY

MALACOLOGIA

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VOL. 9 NO. 2 DECEMBER 1969

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MALACOLOGIA, 1969, 9(2): 313-325

VELUTINELLUS, NOUVEAU GENRE FOSSILE DE LA FAMILLE
DES LYMNAEIDAE, ET SES RELATIONS AVEC VELUTINOPSIS
ET VALENCIENNIUS

Florian Marinescu

Institute Geolagique du Comite Geologique, Bucarest, Roumanie

RESUME

Cette note comprend la description de 4 Lymneides provenant de gisements situés sur
le versant oriental des Carpates Meridionales (Bassin Dacique), en Olténie, Roumanie.
Ces especes sont: Velutinopsis velutina Deshayes, espece peu connue en Roumanie, pro-
venant du Méotien inférieur, Velutinopsis codapavonis sp. n., du Pontien inférieur, et 2
espèces appartenant au genre nouveau Velutinellus: Velutinellus catinus sp. п. (catinus=
encensoir romain) et V. pilleus sp. n. (pilleus=bonnet distinctif des nobles daces), aussi
du Méotien inférieur.

Le genre Velutinellus est caracterisé par la grande expansion du péristome, qui déborde
largement la spire tres réduite. Les formes décrites anterieurement sous les noms de
“* Lymnaea ” amplecta Gorjanovic-Kramberger, Velutinopsis rugosa Gorjanovic-Kram-
berger et V. transiens Moos sont, elles aussi, attribuées a Velutinellus.

Le développement ontogénétique des coquilles de Velutinellus suggére que ce genre
dérive de Velutinopsis velutina et qu'il se гейе a Valenciennius par Vintermédiaire de Pro-
valenciennesia. La ligne philetique présumée, appellée ici * ligne évolutive valencienne
des Lymnéides,” serait la suivante:

Radix—>Velutinopsis—>Velutinellus—>Provalenciennesic—>Valenciennius
N Undulotheca

L’auteur suppose que les espèces pannoniques Velutinellus rugosus et Г. transiens
proviennent des formes decrites du Bassin Dacique, qui auraient émigié dans le Bassin
Pannonique a cause d’une augmentation de la salinité dans le Bassin Dacique lors de la
sedimentation des couches a Dosinia. La forme plate des coquilles, caractéristique des
genres Undulotheca, Provalenciennesia et Valenciennius represente une adaptation aux
conditions speciales de vie dans un bassin dont le fond est constitué de vase imbibee d’eau.

La position systematique du genre Valenciennius. Les formes de Radix sont
Valenciennius Rousseau, 1842, connu du signalées des le Sarmatien; celles
Pliocene supérieur (Pontien), est encore Velutinopsis et Valenciennius sont connues

suet a discussion: certains auteurs en
font une famille indépendante, alors
que d‘autres s’opposent a ce qu’on le
sépare de la famille des Lymnaeidae.
Malgré ces divergences, tous sont d'accord
pour reconnaitire sa descendance d'une
forme de Radix, par l’intermediaire de
Velutinopsis Sandberger, 1875, et de
Provalenciennesia Gorjanovic-Kramberger,
1923, et pour placer son évolution dans
le secteur sud-est du Bassin Pannonique.
Les seuls représentants de cette filiation
connus jusqu'a présent dans le Bassin
Dacique ont été Radix, Velutinopsis et
1

313

du Pontien. Dernierement, Velutinopsis
a été mentionnée dans le Méotien supérieur
aussi.

Le tres riche matériel paléontologique
du Néogene supérieur du Bassin Dacique
(surtout de l’ouest de l'Olténie-Roumanie)
a fourni quelques formes de cette famille,
quí. n'ont раз “encore été décrites et
dont deux représentants forment un
nouveau genre: Velutinellus. Certaines
formes de Velutinopsis, déja décrites,
telles que Velutinopsis rugosa Gorjanovic-
Kramberger, Г. transiens Moos ainsi
que “ Lymnaea” amplecta Gorjanovic-

314 FLORIAN MARINESCU

FIG. 1. Carte montrant l'emplacement des gisements mentionnés (+) en Roumanie, particulièrement
en Olténie (1), ainsi que les bassins où se sont développés les Lymnaeides du groupe Valenciennius. TS
Turnu Severin; Cr, Craguesti; Iv, Ilovat,; Bg, Bengesti; 1, gisement du vallon Fintinele; 2, vallée lazostea
3, gisement d’Ilovat: 4, Soceni. BP, Bassin Pannonique; BD, Bassin Dacique; BEx, Bassin Euxinique
т, voie présumée de migration a travers les Carpates méridionales.

Kramberger, sont aussi placées dans ce ontogénétique des coquilles de Velutinellus
genre. ont suggéré leur position intérmédiaire
Les observations sur le développement entre Velutinopsis et Valenciennius.

Genre Velutinopsis Sandberger, 1875
Espece type Lymnaea velutina Deshayes
Velutinopsis velutina (Deshayes, 1838)
PI. I, Fig. 4-5

1838 Lymnaea velutina Deshayes, Мет. Soc. Géol. Fr. ser. 1, t. Ш, 1, p. 64,
pl. V, figs. 12-14.

1923 Velutinopsis velutina (Deshayes); Wenz, Fossilium Catalogus, pars 21, p. 1326
(avec synonymie).

1942 Radix (Velutinopsis) cf. velutina (Deshayes); Wenz, Senckenbergiana, Bd. 24, p. 68,
pl. 24, fig. 380.

1944 Velutinopsis velutina Deshayes; Moos, Vestnik drz. geol. Zavoda II/III, р. 345,
р] ХХ 155: 3—5:

Jusqu’a presént cette езрёсе a été Roumaine), a Bengesti (Olténie septen-
rencontrée surtout dans le Pontien trionale, Roumanie), mais les exemplaires
(Pliocene) par I. Motas (de l'Institut de mentionnés ne sont pas précisément

Géologie et Geographie de l’Académie typiques: ile ont la coquille plus épaisse

VELUTINOPSIS, G.N. 315

et Гарех un peu plus éleve. Les deux
exemplaires plus anciens que nous possé-
dons, provenant du Méotien inférieur,
ont une coquille presque lisse et ornée
seulement de stries d’accroissement, dont
quelques-unes sont mieux marquées. La
spire est tres petite, représentée seulement
par deux tours; Гарех ne dépasse pas
en hauteur le niveau de la spire. Le
dernier tour, large et bien développé,
s'achève par une ouverture ovalaire,
très évasée. Le bord columelliare du
péristome est faiblement soudé à la
coquille.

Le gisement se trouve dans le vallon
Fintinele [Fig. 1 (1), texte] affluent
droit de la vallée lazostea. a l’ouest de
Craguesti, Olténie.

Age: Méotien inférieur. Lun des
exemplaires a été trouvé dans l'horizon
basai, a graviers, avec plusieurs exem-
plaires de Theodoxus (Ма) geticus
Marinescu, Unio subrecurvus Teisseyre
et quelques espèces de Teisseyreomya et
Congeria. Le deuxième provient du même
gisement, mais à 2 m au-dessus, du
niveau à Dosinia maeotica Andrusov.

Velutinopsis codapavonis sp. n.
РТ. Г. Figs- 1-35 Fig 2 texte

Coquille mince, très fine, peu bombée,
entiorme de Casquette. La “spire tres
petite basse, а deux tours: Гарех пе
dépasse pas le niveau de la spire. Le
dernier tour, extrêmement développé, a
les bords trés évasés, en éventail, ou en
queue de. paon (dow le nom). La
partie ventrale de la coquille n’est pas
visible, mais le bord columellaire du
péristome ne parait pas étre soudé a la
spire.

Dimensions de 3 exemplaires, en milli-
metres:

holo- paratypes
type

hauteur de la

spire: 1,2 2,0 1,0

longueur de la

coquille: ES 6,67 24:0
largeur du péris-

tome: 3,0 5.5 3:3
hauteur du peri-

stome: 6,8 7,0 330

La coquille étant tres fine, les exemplai-
res n’ont pu étre détachés de la roche.
Cette espece est nettement différente de
toutes les especes de Velutinopsis connues.
Le développement exagéré du dernier tour
en est tres caractéristique. Il entraine le
développement de la largeur du péristome,
qui représente plus de quatre fois la
hauteur de la spire. Le bord postérieur
de ouverture ne dépasse pas la spire. On
remarque que cette partie postérieure est
bordée par une nervure tres fine, qui lui
donneun plus de résistance. Les exem-
plaires ont été trouvés dans le versant
gauche de la vallée Cosustea, a Ilovat,
Olténie [Fig. 1 (3), texte], en amont du
pont Borcanesti, dans les argiles marneuses
bleu cendré, conchoides, à plusieurs
Ostracodes, Radix et a quelques petits
exemplaires de Valenciennius. Au-dessus
se trouvent des argiles marneuses a
Congeria digitifera Andrusov, Paradacna,
Didacna otiophora Brusina. recouvertes
par des argiles marneuses a Limnocardium
zagrabiense Brusina et nombreux exem-
plaires de Valenciennius (zone В,
Marinescu, 1964).

Le niveau type se trouve а 2,5 т
environ au-dessus de la limite Méotien-
Pontien, a la partie supérieure d'une
intercalation de 20 cm d’argiles sableuses,
d'age Pontien inférieur.

Genre Velutinellus g. n.

Coquille en casquette ou capuchon,
ordinairement lisse, couverte seulement
de stries d'accroissement, plus rarement a
plis plus ou moins accusés. La spire est
très petite, réduite à 1-2 tours, aplatie.
Le dernier tour a un accroissement très
rapide, le diamètre presque égal à la

316 FLORIAN MARINESCU

es)
Q
159)

Velutinopsis codapavonis sp. п. (holotype).
FIG. 3. Velutinellus catinus gen. n., sp. п. Stades de développement dans une même coquille (holotype).
FIG. 4. A. Profil de Velutinellus pilleus et B. de Velutinellus catinus (holotypes).

FIG. 5. Velutinellus pilleus gen. п., sp. п. Stades de développement dans une même coquille (holotype).

VELUTINOPSIS, G.N. 317

hauteur. Son ouverture, circulaire ou
elliptique, est tres large et se développe еп
dépassant la spire par son bord postérieur,
qui est libre (non soudé a la coquille).

Par ses caracteres, Velutinellus est nette-
ment different de tous les autres
genres des Lymnaeidae. Il est vrai que,
pendant les premiers stades de dévelop-
pement, les coquilles de Velutinellus
présentent des ressemblances avec Jes
exemplaires adultes de Velurinopsis, mais
au cours de leur évolution uitérieure
elles prennent une direction différente;
c'est pourquoi Velutinellus a été considéré
comme un genre indépendant. Le nom
dérive de Velutinopsis velutina, ancêtre
présumé des formes que nous allons
décrire.

Les données connues nous permettent
d'assimiler à Velurinellus l'espèce * Lymn-
аеа amplecta de Gorjanovic-Kramberger
(1901: 136, pl. X, figs. 13-14). Bien que
les exemplaires figurés soient incomplets,
les traits du dernier tour sont très proches
de ceux de Velutinellus. L’exemplaire
figuré par Moos (1944: pl. XXI, fig. 6)
comme Velutinopsis rugosa présente, lui-
aussi, certains caractères génériques de
Velutinellus. Cet exemplaire se distingue
de celui figuré, en dessin, par Gorjanovic-
Kramberger (1901: pl. X, fig. 16) comme
type de Гезресе et qui appartient plutôt
au genre Velutinopsis. Quant a Velutinop-
sis transiens Moos (1944: pl. XXII,
fig. 10), dont l'ouverture dépasse la spire,
cette espèce appartient elle-aussi au genre
Velutinellus.

Velutinellus catinus с. n., Sp. п.
(espèce type)
Pl. L Figs. 9-12, Figs. 3, 4B, texte.

Coquille de petites dimensions, en cas-
quette ou en assiette, recouverte de fines
stries d’accroissement et de rides
irrégulierés, peu marqués. La spire, tres
petite, basse, se réduit a un seul tour,

Le dernier tour, pas très haut, s’élargit
rapidement. L’ouverture, ovoide ou
subcirculaire, a les bords étendus: le
bord postérieur dépasse la spire.

Dimensions (mm): holo- — paratypes
type
hauteur de la
spire: 62 1.0 11
hauteur de la
coquille: 5:0 —.2:2 2,0
largeur du
péristome: 0: 274.8 4,6
hauteur du
péristome: 10,5 2 SAD

Le nom refléte sa ressemblance avec les
encensoirs (cassolettes) des romains.
nommés catinus ou catinum. Pendant le
développement de Velutinellus catinus
(Fig. 5, texte) les stades jeunes sont
semblables a Velutinopsis velutina. En-
suite, le dernier tour se développe très
rapidement, sans qu'il у ait, toutefois,
une difference trop grande entre la
rapidité de croissance de la partie antéri-
eure et celle de la partie postérieure;
par conséquent, les stries d’accroissement
les plus accusées forment entre elles des
angles faibles (89-159). La coquille est
ornée de plis peu marqués, plus évidents
dans la région antérieure, recouverts a leur
tour de fines stries d'accroissement (pré-
figuration des anneaux de Valenciennius?)
Dans la région latéro-postérieure de la
coquille, il y a un sillon siphonal á pcine
visible, situé exactement dans une petite
courbure de l’ouverture, a l’endroit ou,
chez les Radix actuelles, il y a le pneu-
mostome.

Gisement: Les graviers du Méotien
inférieur vu vallon Fintinele, à l’ouest de
Craguesti, Olténie (Fig. 1, texte), a 1, 5m
au-dessous du niveau à Dosinia maeotica,
à côté de Congeria ramphophora Brusina,
Unio subrecurvus, Teisseyreomya subatava
(Teisseyre) etc. C’est encore de cet endroit
que provient un des exemplaires décrits
de Velutinopsis velutina et les exemplaires
de Velutinellus pilleus sp. п,

318 FLORIAN MARINESCU

VELUTINOPSIS, G.N. 319

Velutinellus pilleus ©. n., sp. п.
Pl. I, Figs. 6-8. 4A, 5, texte

Coquille de dimensions réduites, assez
haute, fine, tres fragile, presque lisse,
recouverte seulement de stries d’accroisse-
ment, dont quelques-unes mieux marquées.
La spire est petite, représentée par un seul
tour: l'apex est au niveau de la spire, la
protoconque est bien visible. Le dernier
tour se développe tres rapidement en
lareeur et aussi en hauteur, comme un
entonnoir. L’ouverture, Irrégulierement
elliptique, dépasse la spire de son bord

postérieur.
Dimensions (mm): holo- paratype
type
hauteur de la
spire: 1.3
hauteur de la
coquille: 8.0 3
largeur du
péristome : 13.0 13152
hauteur du
peristome: 15.3 1372

La morphologie externe de cette forme
rappelle le bonnet distinctif des nobles
daces, nommé pilleum ou pilleus.

L’espece decrite diffère de “ Lymnaea ”
amplecta Gorjanovic-Kramberger (1901:
136, pl.X, figs. 13-14), dont on ne connait
pas la spire, par les dimensions plus
reduites par la hauteur proportionelle-

ment plus petite, par Г ouverture allongée
transversalement (dans le sens de la
largeur).

Quant au développement de la coquille
on remarque une premiere étape, de
jeunesse, qui suit la protoconque, pendant
laquelle aspect général est semblable a
celui de Velutinopsis velutina et aussi à
celui de Veluntinellus catinus. Ce n'est
qu'apres cette étape que le bord postérieur
du péristome commence a se développer
plus rapidement, en dépassant la spire,
dont les dimensions restent tres réduites
(Fig. 3, texte). Ainsi les stades adultes
des deux espèces deviennent nettement
différents, le dernier tour de Velutinellus
catinus se développant moins rapidement
en hauteur que celui de И. pilleus. La
partie antérieure de la coquille se
développe a une allure considérablement
plus grande que la partie postérieure: les
stries de croissance qui sont rapprochées
se rejoignent en un même point dans la
partie postérieure, au-dessous de la spire.
Toutefois. a des distances presque égales
il y a des plis mieux marqués: les plis
rapprochés forment entre eux des angles
de 259-309 (Fig. 4A, texte). Dans la
région latérale et postérieure on peut
observer un sillon a peine visible, comme
chez l’espece précédente.

Gisement: Graviers fossiliferes du
Méotien basal, dans le méme niveau que

RIGS ele 3:

Cosustea, a Ilovat, au nord de Turnu Severin, Olténie [Fig. 1(2), Texte! (5х). FIG. 1.

FIGS. 2-3. Paratypes.

Velutinopsis codapavonis sp. n. Pontien inférieur, argiles marneuses; rive gauche de la vallée

Holotype.

FIGS. 4-5. Velutinopsis velutina Deshayes. Le vallon Fintinele, à Huent de la vallée lazostea; Cráguesti,

au nord de Turnu Severin, Olténie [Fig. 1(1), texte] (2x).
Méotien inférieur. horizon inférieur, a Cor geries et Teisseyreomva; a, vue apicale; b,

sables. .-FIG. 5.
vue dorsale.

FIGS. 6-8. Velutinellus pilleus gen. n., sp. п.

FIG. 4. Méotien inférieur, horizon a Dosinia:

Méotien inférieur, horizon inférieur, a Tesseyreomya

et Congeries. Le vallon Fintinele. FIG.6. Holotype; a, vue dorsale; b, vue apicale; с, vue postérieure

(2x). FIG. 7. Exemplaire jeune (10x). FIG. 8.

FIGS. 9-12. Velutinellus catinus gen. n., sp. n.

a, vue dorsale; b, vue apicale; c, vue postérieure (2x).

Méme horizon, méme gisement, FIG. 9.

Paratype; a, vue apicale; b, vue dorsale (2x).

Holotype:
GFIS. 10-11. Paratypes; a, vue dorsale; b, vue

ventrale (4x). FIG. 12, Exemplaire jeune; a, vue apicale; b, vue dorsale (5х),

320 FLORIAN MARINESCU

BASSIN PANNONIQUE | BASSIN DACIQUE
F Ts Te = |
jo pices
Y i |
|
5 Z.
À El
| Zz (migration Е |
УЕ vers le Bassin |
Е Euxinique) ©
и. В. |
=
я ]
| = = velutina* |
| N © 3 ; |
AA 2 - q V-opsis codapavonis | |
| | x ee eee = a aoe en
| | = . С | |
< О
| | V-lus = , A
3 YULOSUS © 2 .
o | ( Ss : Q
| - = “ -
\® | V-opsis S : =
el e
5 | velutina © : H
2 | Q, : = = Е Cae ore en a nn. |
V-lus Seh nern =
| lransiens a р |
ЕЕ -А---------=-^-- GH SSS Ss ; S| El
р | : Фан |
|
Е £Q ©
Y $ = 3.0 el
En V-opsis . = =
ES nobilis y 1 E
“mA 20 0 Ô SE is Se SE Se -
ess Y
ZlsO Sl =
als à Е
Slee =
= 78 3 V-lus
2 => | S YUgOSUS V-opsis V-lus V-lus
ам | velutina pilleus catinus
ott = |
= |
| =
rl AA TE TEA re MU EAN (A SE > eet EEE =
ON Er © |
Е 5
= ©
5
= =
> о
Xa) Steet oe See ЕЕ ЕЕ eee |
[Fast | 72 |
= Radix croati s |El
| adix croatica 2 =
N £ T | oe
| | pa S
| w
| Area
| | » | <
(ue ie ee ER дм
| = |
5. Е
2) | >
a | | =
à al | 2
| | >

“Cette forme pourrait étre une variété ou méme une sous-cspece.

TABLEAU 1. Les relations phylogéniques problem de Velutinellus avec Velutinopsis et Valenciennius

Velutinellus catinus sp. n., a 1.5 m au- ques qui caractérisent les différentes
dessous du niveau а Dosinia. dans le vallon especes, l'évolution des Lymnaeides est
Fintinele, à l’ouest du village Craguesti marquée, a partir de Radix, par la
(Olténie). reduction de la spire et l’accroissement

considérable du dernier tour, entrainant

DISCUSSION SUR LES RELATIONS le développement du péristome qui s'évase.
PHYLOGENIQUES DE Nous avons nommé cette orthogenése,
VELUTINELLUS qui conduit a Valenciennius, “évolution
valencienne des Lymnaeides ”. Radix

Mis a part les caractères morphologi- kobelti Brusina est un des nomzreux

VELUTINOPSIS, G.N. 321

exemples qui indiquent cette tendance,
sans dépasser pour autant le cadre admis
pour le genre.

А partir, probablement, de Radix
croatica Gorjanovic-Kramberger (Moos,
1944) c'est un nouveau genre qui se
détache, Velutinopsis (Tableau 1), dont
l'unique représentant repéré jusqu'a
présent dans le Bassin Dacique, Ve/utinop-
sis velutina, apparaît au Méotien in'érieur,
dans l'horizon antérieur a Vhorizon à
Dosinia maeotica (c'est à dire dans le
‘* Susswasser Bank” des “ Dosinien-
Abteilungen ” de Krejci Graf, 1926).

Du genre Velutinopsis se détache, dans
le Bassin Pannonique, comme branche
collatérale, Undulotheca Gorjanovic-
Kramberger. 1923, dont le convergent
est Velutinopsis nobilis Reuss. Cette
branche ne continue pas l'évolution valen-
cienne. Les formes 4` Undulotheca atteig-
ent rapidement des grandes dimensions,
sans donner une trop grande variété
morphologique; elles sont douées d'une
ornamentation de type Valenciennius, mais
présentent une morphologie semblable a
Velutinopsis. Cette branche s'éteint vite,
vers la fin du Pannonien str. s., avant
d’avoir pu traverser la barrière carpatique.

Le genre Velutinellus se détache de
Velutinopsis, presqu en même temps que
Undulotheca, en suivant la ligne d'évolu-
tion valencienne des Lymnéides. Chez
Velutinellus, le dernier tour, se développe
encore plus: le bord postérieur du péris-
tome déborde la spire, qui garde des
dimensions insignifiantes par rapport
au reste de la coquille. Les deux espèces
daciques de ce genre (V. pilleus et V.
catinus) ont été signalées toujours au
Méotien inférieur, dans le mème gisement
que Velutinopsis velutina: elles sont les
seules connues jusqu'a present dans le
Bassin Dacique. Dans le Bassin Pannoni-
que on peut encore rapporter à ce genre
quelques formes décrites antérieurement:
“ Lymnaea” amplecta, “ Velutinopsis ^
rugosa et “ Velutinopsis” transiens, De

celles-ci Velutinellus rugosus est presque
contemporaine des espèces daciques,
mais présente une morphologie un peu
plus évoluée. Chez les formes extra-
carpatiques—Velutinellus pilleus et Г.
catinus—on observe aussi un très vague
pli de la coquille, placé précisement la où,
chez les formes actuelles de Radix, se
trouve le pneumostome. Avec Provalen-
ciennesia ce pli va s’accuser graduellement,
jusqu'a des exagérations telles qu'on
les trouve chez Valenciennius.

L'évolution ontogénique de Velutinellus
pilleus prouve sa descendance directe de
Velutinopsis velutina, des ses premiers
representants, dont les charactères sont
encore instables, se détache Velutinellus
catinus, forme quelque peu plus évoluée.
Il reste encore à élucider les relations
philogéniques existant entre les formes
daciques de Velutinellus et leurs vicariantes
pannoniques. Il en est de même pour
les rapports des normes pannoniques de
Velutinellus avec Provalenciennesia, vu
que tant Velutinellus rugosus, que Velu-
tinopsis nobilis, qui ont été considérées
comme étant sur la ligne directe d'evolu-
tion (Moos. 1944: Taktakischvili, 1967),
ne semblent être que des formes extrêmes,
qui ne sauraient aboutir au genre
Provalenciennesia. Pourtant les données
que nous possédons а ce sujet n’excluent
pas la possibilité que Provalenciennesia
soit dérivée des exemplaires daciques de
Velutinellus, dont les caractères sont
encore variables et qui auraient migré de
Pest vers l’ouest.

Pour le moment, dans le Bassin Dacique
reste à combler un hiatus entre les formes
de Velutinellus du Méotien inferieur et
celles de Valenciennius connues au Pontien
inférieur. L'interruption est due, en
premier lieu, à la barrière que constitue
l'augmentation de la salinité durant la
partie supérieure du Méotien inferieur,
pour l’évolution de ces formes. C'est
pourquoi les formes de transition doivent
être cherchées dans le Bassin Pannonique,

322 FLORIAN

ou les conditions de salinité restent а peu
pres les mémes. Les autres conditions
de milieu different cependant, puisque
le milieu sableux du Méotien dacique est
remplacé par celui, vaseux, du Pannonien.

Nous ferons remarquer que, d'une
maniére générale. toutes les grandes
formes de Lymnaeidae: Undulotheca, Pro-
valenciennesia, Valenciennius, зе rencon-
trent dans des dépôts argilo-marneux
largement répandus dans la région sud-est
du Bassin Pannonique durant le Pannonien
et le Pontien et dans tout le Bassin
Dacique, durant le Pontien. Ceci laisse
supposer que ces mollusques зе soient
adaptés a ces conditions spéciales, i.e., a
un bassin au fond recouvert de vase fine,
imprégné d’eau, en développant un pied,
dont la surface devait être assez large
pour empêcher l'animal de s’envaser. La
coquille, très mince et aplatie, mais de
grandes dimensions, commence à s’onduler
en devenant de la sorte plus résistante.
Ainsi la zone sud-est du Bassin Pannoni-
que, qui offre les conditions les plus
propices au développement des grandes
formes de Lymneïdes, a joué pour elles
le rôle de niche évolutive.

Grâce a l’évolution rapide de ces formes
on a pu séparer plusieurs horizons dans
les dépôts pannoniens et pontiens du
secteur croate du Bassin Pannonique
(Moos, 1944). Onconnait déjà. dans
le Bassin Pannonique, la corrélation
existant entre les marnes a Undulotheca et
Congeria banatica К. Hoernes, qui représ-
entent le facies de large (Beckenficies)
du Pannonien moyen, et les dépôts
comportant la faune de Soceni (Fig. | (4),
Texte), indiquant le facies littoral (Rand-
facies). D'autre part certains éléments de
la faune de Soceni, surtout des Congeries-
С. ramphophora, С. soceni Jekelius, С.
politioanei Jekelius (Kojumdgieva, 1961,
et données inedites de l’auteur)-sont
connus dans le Méotien inferieur du
Bassin Dacique, d’ou la correspondance
entre le Meotien inferieur et une partie

MARINESCU

du Pannonien moyen (Tableau 1). On
peut donc déduire que pendant que le
genre Undulotheca зе développait dans le
Bassin Pannonique, comme branche colla-
térale, dans le Bassin Dacique apparais-
saient les formes de Velutinellus. Celles-
ci-, derivant de Velutinapsis velutina
(immigrant pannonique dans le Bassin
Dacique, tout comme les Congeries men-
tionnées), émigrent, en revenant vers
l’ouest, où elles trouvent des conditions
meilleures d'épanouissement, vu que
l'augmentation de la salinité qui se
produit au niveau de la faune à Dosinia
empèche leur évolution sur place. Ces
migrations ont été favorisées par le
très riche échange de faunes, qui existaient
dans cette région, entre les deux bassins, à
une époque qui correspond a la plus
grande expansion des dépôts pannoniens
et méotiens. C'est de formes daciques
de Velutinellus que dérive probablement
Velutinellus transiens qui semble être a
l’origine du genre Provalenciennesia.

L” apparition du genre Valenciennius
dans le Pontien semble suivre de tres pres
celle du genre Provalenciennesia, ayant
dérivé des formes primitives de celui-ci.
Cette question devra étre analysée en
détail, parallélement aux études sur les
represéntants daciques de ce groupe.

BIBLIOGRAPHIE

DESHAYES, G. P., 1838, Description des co-
quilles fossiles recueillies en Crimée par М. de
Verneuil et observations générales a leur sujet.
Mem. Soc. geol. Fr., ser. 1, 3: 37-69.

GORJANOVIC-KRAMBERGER, K., 1901, Ue-
ber die Gattung Valenciennesia und einige
unterpontische Lymnaeen. Ein Beitrag zur
Entwicklungsgeschichte der Gattung Valen-
ciennesia und ihr Verhaltnis zur Gattung
Lymnaea. Beitr. z. Pal. Oesterr.-Ung. u. des
Orients, 13: 121-140.

GORJANOVIC-KRAMBERGER, K., 1923, Die
Valenciennesiiden und einige andere Lymnaei-
den der pontischen Stufe des Unteren Pliozans
in ihrer stratigraphischen und genetischen
Bedeutung. Glasnik. hrv. prirod. Drustva,
Zagreb, 35: 87-114,

VELUTINOPSIS, G.N. 323

KOJUMDGIEVA, E., 1961, Etude paléonto-
logique et biostratigraphique du Méotien
inférieur de la Bulgarie du nord-ouest. An.
Dir. Gen. rech. geol., Sofia, 11 (1960): 139-155.

KREJCI GRAF, K. & WENZ, W., 1926, Jung-
tertiare Landschnecken aus Sudrumanien. N.
Jahrb. f. Miner. и. Geol., 55(В): 53-65.

MARINESCU, FL., 1964, Propuneri си privire
la orizontarea Pontianului din partea occi-
dentala a Basinului Getic (Propositions sur les
zones du Pontien de la partie occidentale du
Bassin Getique). Acad. В.Р. Rom., Stud. Cerc.
Geol., 9(1): 73-80. Bucarest.

MARINESCU, FL., 1967, Observations sur le
Pannonien de Caransebes. Acad. R. P. Rom.,
Stud. Cerc. Geol., 12(2): 465-469. Bucarest.

MOOS, A., 1944, Neue Funde von Lymnaeiden,

insbesondere von Valenciennesiiden im Pannon
Kroatiens. Vestnik drz. geol. Zavoda, Agram.
B. (2/3): 341-350.

TAKTAKISCHVILI, I. G., 1967, Historische
Entwicklung der Familie Valencienniidae. Tbilisi
(Ed. Mitzinereba).

WENZ, W., 1923, Gastropoda extramarina ter-
tiaria. Fossilium Catalogus Г Animalia, 21:
1323-1337. Berlin.

WENZ, W., 1942, Die Mollusken des Pliozans
der rumanischen Erdol-Gebiete als Leitver-
steinerungen fur die Aufschluss-Arbeiten. Senc-
kenbergiana, 24: 1-293. Frankfurt.

WENZ, W., 1959, Gastropoda. Teil 2, Euthy-
neura, Lief. 1, (In: O. Schindewolf, Handbuch
der Palaozoologie, Bd. 6), р 94-96. Berlin
(Gebr. Borntraeger).

ABSTRACT

VELUTINELLUS, A NEW FOSSIL GENUS, AND ITS RELATION TO
VELUTINOPSIS AND VALENCIENNIUS (LYMNAEIDAE)

F. Marinescu

This note comprises the description of 4 fossil lymnaeids from beds on the eastern
slopes of the southern Carpathians (Dacic Basin) in Oltenia, Roumania. These species
are: Velutinopsis velutina Deshayes from the lower Meotian, a species not well known
in Roumania, Velutinopsis codapavonis sp. n. from the lower Pontian, and 2 species of
Velutinellus g. n., i.e., У. catinus, sp. п. (catinus roman incenser) and У. pilleus, sp. п.

(pilleus =distinctive cap of dacian nobles), also from the lower Meotian.

Characteristic for the genus Velurinellus is the great expansion of the peristome, which
widely projects beyond the much reduced spire. The forms previously described under
the names of ‘ Lymnaea” amplecta Gorjanovic-Kramberger, Velutinopsis rugosa
Gorjanovic-Kramberger and V. transiens Moos are here also assigned to Velutinellus.

The ontogenetic development of the shell of Velutinellus suggests that this genus derives
from Velutinopsis velutina and that it is related to Valenciennius through Provalenciennesia.
The presumed phyletic line, here designated as the “ valencian evolutive line of the

lymnaeids,” is given as follows:

Radix—>Velutinopsis—>Velutinellus—> Provalenciennesia—>Valenciennius

‚ Undulotheca

The author assumes that the pannonic species Velutinellus rugosus and Г. transiens
originate from the forms described from the Dacic Basin. These have presumably
emigrated into the Pannonic Basin on account of an increase in salinity in the Dacic
Basin at the time of sedimentation of the layers containing Dosinia. The flat shape of
the shell, characteristic for the genera Undulotheca, Provalenciennesia and Valenciennius
is thought to represent an adaptation to the special conditions in a basin whose substrate

consists of soft waterlogged mud,

324

FLORIAN MARINESCU
RESUMEN

VELUTINELLUS, UN NUEVO GENERO FOSIL, У SUS RELACIONES
CON VELUTIN OPSISY VALENCIENNIUS
(LYMNAEIDAE)

F. Marinescu

Esta nota describe 4 limneidos fósiles de los estratos de la falda oriental de los Carpatos
sureños (Cuenca Dácica) en Oltenia, Rumania. Las especies son: Velutinopsis velutina
Deshayes del Meociano inferior, especie no del todo conocida en Rumania; Velutinopsis
codapavonis sp. п. del Pontiano inferior; 2 especies de Velutinellus gen. п., У. catinus
sp. п. (catinus — sahumador romano) у У. pilleus sp. п. (pilleus — gorro distintivo de

los nobles dacianos), ambas del Meociano inferior.

El género Velutinellus se caracteriza por la gran extensión del peristoma, el cual
sobrepasa ampliamente la reducida espira. Las formas previamente descriptas bajo los

nombres de `` Lymnaea” amplecta Gorjanovic-Kramberger, Velutinopsis rugosa Gorj.-

Kram. у И. transiens Moos, se asignan aqui también a Velutinellus.

El desarrollo ontogenético de la conchilla de Velutinellus sugiere que el género deriva
de Velutinopsis velutina y que esta relacionado con Valenciennius a través de Provalien-
ciennesia. La filogenia supuesta, que se designa aqui como ‘la linea evolutiva
valencienna de los Lymnaeidae ” es como sigue:

Radix—>Velutinopsis—>Velutinellus—>Provalenciennesia—>Valenciennus
= Undulotheca

El autor supone que las especies Velutinellus rugosus у Г. transiens se originaron de
las formas descriptas para la Cuenca Dácica. Estos, presumiblemente, emigraron dentro
de la Cuenca Pannonica debido a un aumento de salinidad en la Cuenca Dacica en la
época de sedimentación de las capas con Dosinia.

La forma plana de la concha, caracteristica de los generos Undulotheca, Provalencien-
nesia y Valenciennus, parece representar una adaptacion a las condiciones especiales de
una cuenca cuyo substrato consiste de barro acuoso.

VELUTINOPSIS, G.N. 325
ABCTPAKT

НОВЫЙ ФОССИЛЬНЫЙ РОД VELLUTINELLUS M ЕГО ОТНОШЕНИЕ К
РОДАМ VELUTINOPSIS И VALENCIENNIUS (LYMNAEIDAE)

Ф. МАРИНЕСКУ

В статье приводится описание 4 ископаемых лимнеид из отложений на во-
сточных склонах Южных Карпат (Дацкий бассей), в Олтении, Румыния.

Эти виды следующие: Velutinopsis velutina Deshayes из нижне-мэотических от-
ложений, который не был достаточно хорошо известен в Румынии; Velutinopsis
codapavonis п. SP., из нижне-понтических отложений и два вида из рода Veluti-
nellus g.n., а именно: У. catinus п. sp. (catinus =римская курильница) и Г. pilleus
п. зр.рШеиз=отличительная шапка дацких рыцарей), также из нижне-мэотиче-
ских слоев.

Характерным для раковины рода Velutinellus. является большое расширение
перистома, далеко выдающемся под сильно редуцированным завитком (spire) -
Формы, ранее описанные под названием “Lymnaea” amplecta Gorjanovic-Kramberger,
Velutinopsis rugosa Gorjanovic-Kramberger и У. transiens Moos автор также относит
к Velutinellus.

Судя по онтогенетическому развитию раковины Velutinellus можно предпола-
гать, что этот род произошел от Velutinopsis velutina и что OH родственен
Valenciennius через род Provalenciennesia.

Предполагаемая филетическая линия обозначется как "Валенсийская эво-
люционная линия лимнеид" и представляется в следующем виде:

Radix — Velutinopsis — Velutinellus — Provalenciennesia —> Valenciennius
N Undulotheca

Автор приходит к выводу, что паннонские виды Vellutinellus rugosus и V.
transiens происходят от форм, описанных из Дацкого бассейна. Они вероят-
но эмигрировали в Паннонский бассейн из-за увеличения солености в Дацком
бассейне во время, когда образовались отложения, сожержащие Роза. Уп-
лощенная форма раковины, характерная для Undulotheca, Provalenciennesia и Vale-
nciennius рассматривается как адаптация к особым условиям в бассейне, от-
ложения которых состоят из мягких насыщенных водою илов.

MALACOLOGIA 1969, 9(2): 327-338

GENETIC STUDIES ON BIOMPHALARIA GLABRATA: TENTACLE
AND EYE VARIATIONS

Charles S. Richards

Laboratory

of Parasitic Diseases, National Institutes of Health

Bethesda, Maryland, U.S.A.

ABSTRACT

(With the technical assistance of James W. Merritt)

Selection, isolations, and self-fertilization through 7 generations of albino Biomphalaria
glabrata (Basommatophora: Planorbidae) resulted in progressive increase to a relatively

stable 60% frequency of progeny with tentacle variations

inheritance.

indicating multifactor

At this frequency level progeny of snails with or without tentacle variations
showed the same frequency of the character suggesting incomplete penetrance.

Mating

a tentacle variation albino with a normal strain black-eye and later with a normal strain
wild type В. glabrata resulted in post-cross F, progeny of the albino including tentacle

variations.

The post-cross F, progeny of the black-eye and wild type mates all appeared

normal, but when these were selfed, more than half produced offspring with tentacle

variations.
gested a maternal effect.

These results demonstrated genetic transmission of the character and sug-
The crosses revealed that the eyes were involved as well as

the tentacles and that the character showed variable expressivity: double, branched,
short, absent, or sack-like tentacles; double, absent, or displaced eyes.

The control of freshwater mollusks
which serve as intermediate hosts of
parasites such as the schistosomes involves
many factors, one of the least understood
being molluscan genetics. Newton (1953)
demonstrated that susceptibility of
Biomphalaria (= Australorbis) glabrata
(Say) to infection with Schistosoma mansoni
involves multifactor inheritance. Involve-
ment of genetics in the tendency of B.
glabrata to climb out of water and esti-
vate, thus surviving drought and avoiding
chemical molluscicides, was reported by
Richards (1968). Occurrence of genetic
resistance to chemicals in insect vectors
of disease suggests the possibility of
genetic resistance in mollusks also.
Planning of experimental studies on
mollusks and interpretation of results
should take into account the possible
influence of genetic factors.

Sturtevant (1923) and Boycott & Diver
(1923) showed that sinistral coiling in
Lymnaea peregra is а single-factor recessive

character with maternal inheritance.

Crabb (1927) studied several morpho-
logical variations in freshwater snails,
concluding from his results that the

characters studied were not genetically
determined. Newton (1954) demon-
strated that albinism in Biomphalaria
glabrata is genetically determined by a
single recessive factor showing Mendelian
inheritance. Richards (1967) has des-
cribed a third pigmentation allele, “* black-
eye ”, dominant over albino but recessive
to wild type pigmentation.

One of the characters studied by Crabb
(1927) was forked tentacle in Physa gyrina
and Lymnaea stagnalis appressa. Davis,
Moose & Williams (1965) described
a specimen of a hybrid Oncomelania with
abnormalities of tentacles and eyes.
Tentacle abnormalities are not uncommon
in most freshwater snails, being generally
attributed to disease, mechanical ог
chemical damage or irritation. Wong &
Wagner (1956) observed tentacular branch-

CHARLES 5. RICHARDS

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BIOMPHALARIA GLABRATA: GENETICS

329

TABLE 1. Comparison of tentacle variation production; for all snail isolations for all progeny deriving
from F,-f, and for a succession of isolations from F,-f of snails with normal phenotypes.

Generation Average |
AE 3 |

(Fig. 1) Of all isolations |
| |
E, 16% Tv
Е, 28% Ту
Es 40% Tv
F, 47% Tv
Es SOIT
F, i

* Insufficient isolations for comparisons.

ing in 4 specimens of Oncomelania in
several thousand, and demonstrated it
could be induced by ultraviolet light. The
appearance of several young Biomphalaria
glabrata with either double right or left
tentacles among the offspring of an albino
snail suggested inheritance might be invol-
ved and led to the studies reported here.

MATERIALS AND METHODS

Albino and wild type pigmented Biom-

FIG. 1.
generations by isolation and self-fertilization.
and tentacles.

Re 57% Ev

Progeny deriving from F,-f

Average of all

Succession of normal phenotypes

phalaria glabrata descended from a cross
between Brazilian albino and Puerto
Rican wild type snails (Newton, 1955) and
the “ black-eye * mutant (Richards, 1967)
were used in these studies. Snails were
reared in 400 ml beakers with Petri dish
covers, in aerated tap water, and fed
Romaine lettuce.

Albino snails were reared in isolation
and progeny were obtained by self-
fertilization. Young snails with tentacle
variations (Tv) and normal appearing

Selections for tentacle variation production in albino Biomphalaria glabrata through 7
PA was the parent albino.
“N ” within the diagram indicates a normal appearing snail. “X

Diagrams represent head
” within the diagram

indicates a snail mated after it had produced progeny by self-fertilization,

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BIOMPHALARIA GLABRATA: GENETICS 391

controls (Tn) were selected for isolation
and rearing. Selection, isolated rearing,
and self-fertilization were followed through
7 generations in appreciable numbers, a
few snails being followed Гог several
additional generations.

Albinos showing tentacle variations,
following self-fertilization, were mated
with either black-eye or wild tyve snails
from normal strains. One of the F,
generation albinos was mated twice follow-
ing self-fertilization, first to a black-eye.
and later to a wild type snail. Snails were
mated for one week, after which they were
reisolated and their subsequent progeny
followed. In the following, “A” indicates
albino, “В” black-eve. and “С” wild type
pigmentation.

RESULTS

Successive selections with isolations and
self-fertilization

Results of selection, isolations, and
self-fertilization through 7 generations
are sFown in Fig. |. Tentacle variations
occurred on either right, left. or both
sides (Fig. 3A), including: double tentacles.
branched tentacle, short tentacle, tentacle
absent, or enlarged contractile sac. (It
was not discovered that eye variations
were also involved until later when
matings with snails with pigmented eyes
were performed). Tentacle variations
were observed in 0% to 9% (avg. 45%)
of the progeny of 5F, snails; 1% to 11%
(avg. 45%) of the progeny of 9 Е, snails:
0°% to 57% (avg. 16°%) of the progeny of
15 F, snails; 0% to 65% (avg. 28°) of the
progeny of 14 Е, snails; 10% to 80%,
(avg. 40% of the progeny of 15 Е; snails:
and 8 to 67% (avg. 47%) of the progeny

of 13 F, snails. The progressive and
persistent increase in Tv frequency associ-
ated with selection suggested inheritance.

Tentacle variations in progeny of normal
appearing snails

Production of 6% F, Tv progeny by
F,-a (Fig. 1), which appeared normal, was
attributed to overlooking some slight
abnormality in F,-a. When normal F--h
and F;-K produced 73% and 47% Tv
progeny, however, more “normal”
snails were included in subsequent
selections. The average Tv frequency in
progeny of the 13 isolated F, generation
snails was 47%. Of the 13 snails the 4
Е; Tn snails averaged 48%, Tv progeny;
the 9 F, Tv snails 46°,. Beginning with
F,-K, data were obtained on 4 successive
generations of “ normal ” isolated snails,
The Ту progeny frequencies of these Tn
snails are compared in Table 1 with the
overall Tv frequencies of progeny of F,-f,
and with averages of Tv frequencies of all
snails in each generation. Not shown in
Fig 4, Ed “and: Fe (13-Tv/27 and 22
Tv/3%) and Pa and Eb (10 Ty/20
and 7 Tv/10) were averaged because of the
small numbers.

Matings to determine if transmission is
genetic

Albino F,-b with a double right tentacle,
which produced by self-fertilization 7%,
Tv progeny, was mated with a Tn wild
type hybrid (P-Ca-1) The post-cross
F, progeny of P-CA-1 (in € : A ratio | : 1)
were all normal. Ten pigmented and
10 albino F, offspring were isolated and
reared. The pigmented snails produced,
by self-fertilization, all Tn F, progeny in
3 : 1 (total observed 579C : 201A) ratio.

FIG. 2. Diagram showing the results of mating an albino Biomphalaria glabrata (F,-F in Fig. 1) with
tentacle variation, first with a normal black-eye В. glabrata, and 6 weeks later with a normal wild type
B. glabrata, Diagrams with fine lines and without eyes indicated represent albinos, diagrams with heavy
lines and showing eyes represent black-eyes, and diagrams with shading and eyes represent wild type

snails.

Loe)
Ww
No

CHARLES S. RICHARDS

3A AA-Far

66/110 | 60% Tv

a Se
Wa doth kare te
38 P-BA-2, POST-X, Fı.ı x

BA-F2.) ° 3
16/30 | 53% Tv

RS
| Baader oo
3C P-CA-3, POST-X, Fis ЖК

CA-F2-1

17/61

28% TV

A _ о
OSO ыы OOM Ch

FIG. 3. Examples of the range of expressivity of tentacle and eye variations among progeny of 3 indi-
vidual isolated Biomphalaria glabrata reproducing by self-fertilization. Albinos, black-eyes, and wild

type snails are represented as in Fig. 2

ЗВ shows the offspring of black-eye F,-j from the first cross in Fig. 2

ЗА shows the offspring by self-fertilization of albino F,-f (Fig. 1).

3C shows the offspring of wild

type F,-i from the second cross in Fig. 2 (F;-i, and Fy-l in Fig. 2 were snails produced by F,-i after the

tabulafıon summarized in Fig. 3C had been made).

The isolated albinos produced 607 obser-
ved progeny, all Tn albinos.

The above cross, involving an albino
with low Ту frequency in its offspring,
failed to demonstrate transmission of the
character in cross-fertilization. Subse-
quently albino F,-f, with branched left
tentacle and with 60% Tv frequency т its
progeny by self-fertilization, was mated
twice (Fig. 2). The first mating was with
a black-eye hybrid (P-BA-2) which had
produced all Tn black-eye (17B) and
albino (6A) progeny in 3 : | ratio by self-
fertilization. The albiño and black-

eye parents both produced F, progeny in
| : | ratio (В : A) after mating, indicating
reciprocal cross-fertilization.

Albino F,f produced 103A:97B
post-cross F, progeny with 29 (14%)
showing tentacle variations. Eye abnor-
malities were also observed in black-eye
F, snails. These were usually associated
with tentacle variations, both apparently
being manifestations of the same genetic
factors influencing development. Eye
abnormalities, on either or both sides
(Figs. 2, 3B, and 3C), included: double
eyes, eye absent, eye enlarged or reduced,

BIOMPHALARIA GLABRATA: GENETICS

TABLE 2. Frequency of tentacle variations in progeny of abnormal snails before and after mating

with normal snails.

Normal mate

Pre-cross Snail

Genotype progeny; Tv | No.
frequency (Fig. 1)

CA 0% Е.-а

СВ 09%. > F3-b

CB 0% F;-h

BA 0% Fa-k

BA 0% F,-c

BA 0% F,-f

CB O% F;-a

CB 0% F.-b

| SE :

Totals | 8

eye displaced forward or backward. A
series of post-cross F, offspring were
isolated, those that produced F, progeny
by self-fertilization being shown in Fig. 2.
Two of 6 Е, Tv snails produced F, Tv
progeny (14% апа 3%); 210 9 FE, In
snails produced Е, Ту progeny (1% and
4%).

All the post-cross Е, progeny (68B:
62A) of P-BA-2 appeared normal. Nine
of 17 isolated Е, Tn snails which produced
F, progeny by self-fertilization produced
F, Tv snails in frequencies ranging from
2% to 14%. This indicated the tentacle
and eye variations were genetically control-
led and had been transmitted from F,-f
by cross-fertilization.

Six weeks after the first cross F,-f was
mated with a Tn hybrid wild type pigmen-
ted snail P-CA-3. Р-СА-3 has produced
55С:6А Е, progeny by self-fertilization.
With the numbers involved, the departure
from the expected 3 : | ratio is not unusual
and still demonstrated the dominance of
the gene for pigmentation. One of these
F, snails had an abnormal tentacle.
Whether this was genetic or due to mech-

Albino with tentacle variation

Tentacle variations
in pre-cross progeny
by self-fertilization

Tentacle variations
in post-cross progeny
by cross-fertilization

Tv/total Ту % Tvitotal NV
progeny progeny |
7/82 9%, 5/56 9%
7/56 13% 13/153 9%
12/80 150, 7/78 90,
15/40 38% 1/90 15%
29/83 35% 11/88 1392
66/110 60% 29/200 14%
44/96 469, 7/97 7%,
8/10 80% 19/114 moe
188/557 34% 92/876 MIA

anical or other cause could not be deter-
mined, since it failed to produce viable
offspring. Both F-,f and P-CA-3
produced’ Е; progeny=in 1:1 (С: A)
ratio after mating, indicating reciprocal
cross-fertilization.

Albino F,-f produced 39А:33С post-
cross F, progeny, 36 (50%) with tentacle
(oriseye)- vanıatıons.. Five. of 39°F ТУ
snails isolated produced F, Tv progeny
in frequencies ranging from 2% to 11%;
2 of 8 Е, Tn snails produced F, Tv progeny
29/10/4977

All the post-cross Е, progeny (26С:23А)
of P-CA-3 appeared normal. Fourteen

of 19 Е, Tn snails isolated produced
F, Tv progeny by self-fertilization in
frequencies ranging from 2% to
24%.

A limited number of snails from both
crosses were followed, by isolation and
self-fertilization, through additional gene-
rations. Although Tv frequencies varied
there was a general increase. Twenty-one
of 37 Е. snails followed produced Е.
Tv progeny in frequencies ranging from
090 *10 753%; and 19 of 23° oF; “snails

334 CHARLES S. RICHARDS

TABLE 3. Comparison of tentacle variations in progeny before and after mating of snails all with high

Tv production.

Pre-cross F, progeny by

à self-fertilization
Parent pigment A

|
| —
|
|

Post-cross F, progeny by
cross-fertilization

*Numbers not available.

produced F, Tv progeny in frequencies
ranging from 0% to 68%.

Effect of mating on tentacle variations
production

Albino F,-f produced 60% Tv progeny
by self-ferilization; only 14%, after mating
with P-BA-2 (0°% Tv progeny by self-
fertilization). Comparable results were
obtained in 7 other matings as shown in
Table 2. The albino parents involved in
crosses are indicated by “x”s in Fig. 1.
Tv frequencies in their pre-cross progeny
ranged from 9% to 80% (avg. 34% based
on snail numbers). All produced mixed
phenotype post-cross Е, progeny in | : |
ratios indicating cross-fertilization, with
Ту frequencies ranging from 1%, to 17%
(avg. 11%).

Two crosses were made in each of
which both mates had produced high %
Ту progeny Бу self-fertilization. The
results are shown in Table 3. In the first
cross a BA hybrid producing 53% Tv
progeny by self-fertilization was mated
with an albino producing 43%. Post-
cross pigmentation ratios indicated recip-
rocal cross-fertilization. Post-cross %

Ту progeny increased for both snails.
The second cross was between a CC and
an AA with pre-cross Tv progeny 41%
and 50% respectively by self-fertilization.
The wild type snail died after mating
without laying any eggs. The albino
produced all pigmented post-cross progeny
with 629%, Tv offspring.

DISCUSSION

The progressive increases in frequency
of Tv progeny with successive generations
of selection and self-fertilization (Fig. 1)
indicate inheritance of the characters.
Increase by steps through several gene-
rations suggests multifactor inheritance.
In the more successful series such as that
leading to F,-f, the major steps appear
to be approximately 3X increases. Mat-
ings with normal snails producing 0%
Ту in their pre-cross progeny resulted in
an average decrease in the post-cross Tv
progeny of the Tv parents to 1/3 the pre-
cross frequency (Table 2). These results
suggest a genetic mechanism rather than
cytoplasmic inheritance or infection (viral
or bacterial).

BIOMPHALARIA GLABRATA: GENETICS

FIG. 4. Snail with double right tentacle.

Although some of the series shown т
Fig. | continued to produce variable and
low Tv frequencies as long as followed,
the progeny derived from F,-f (28%
never dropped below 18% Tv production.
This series appeared to reach a relatively
stable plateau of Tv frequency production
of about 50-60%. The few selections
followed for several generations beyond
those included in Fig. | average 50-60°,.
Three high frequencies (F;-b, 80%: F;-8,
70%; and F;-h, 73%) are based on small
numbers and are not significant. None of
the snails was observed to produce 100%,
Ту progeny. Frequencies shown are
conservative, however, since minor
tentacle variations might be overlooked
and eye variations were not included in
the albino series.

Two crosses between snails with pre-
cross Tv progeny near 50%, resulted in
post-cross Tv progeny production as high
or higher than before mating (Table 3).

Whatever the gene combination involved
consists of, it apparently exerts its influence
in embryonic development and results
in a variable “ expressivity ” as illustrated
in Figs. 3A, 3B, and 3C. Selections of a

tn
ios)
Nn

FIG. 5. Snail with double right tentacle and
right eye displaced backward.

single variation, such as double right
tentacle, through a series of generations
resulted in increasing Tv frequencies but
the expression of tentacle abnormalities
continued to be variable. The frequent
occurrence of an enlarged contractile sac
in place of a tentacle (usually on the left
side) was an interesting expression of the
Tv character. Circulation of hemolymph
in the extension of the hemocoel into a
normal tentacle may be observed to be
aided by peristaltic contractions of the
tentacle. The contractile sac appeared
to be a shortened and expanded tentacle
with rhythmic contractions forcing the
hemolymph, red in the case of Biompha-
laria glabrata, in and out of the sac.

As shown in Table 1, the progeny
derived from snail F,-f (60% Tv
production) through 3 succeeding gene-
rations continued to average 50%, or more
Tv production. Selections of normal
appearing snails for 4 succeeding gene-
rations from F,-f continued to produce Tv
frequencies comparable to, ог slightly
higher than, the Tv snails in the same
generations. This suggests that these
Tn snails might be carrying the same

336 CHARLES 3. RICHARDS

genetic composition as F,-f and its Tv
progeny, and this genetic composition
might represent a homozygous condition
with incomplete (50-60%) penetrance of
the phenotypic expressions.

In both of the matings with F,-f, the
post-cross F, progeny of P-BA-2 and
P-CA-3 all appeared normal while some of
the post-cross progeny of F,-f in each
case showed tentacle and eye variations
suggesting a maternal effect. As many
(actually more) of the isolated post-cross
F, snails of P-BA-2 and P-CA-3 produced
Tv progeny as the post-cross F, snails
from F,-f. This supports the suggestion
that maternal inheritance may be involved
in this character, as in reverse coiling in
snails (Sturtevant, 1923; Boycott & Diver,
1923).

In his attempts to demonstrate inheri-
tance of characters in snails, Crabb (1927)
concluded: * The only instance in all the
cultures which suggested inheritance of
any of the distinguishing characters was
that of an Е, Physa gyrina which had a
prong on the medial side of its right
tentacle near the tip, as had its mother,
but it also had a prong on the medial side
of the left tentacle near the base, which did
Bot “occur un thesmother. 7 Lt the, 3
suggested phenomena in tentacle variation
inheritance (variable expressivity, incom-
plete penetrance, and maternal inheritance)
occur in other genetic characters in
mollusks, failure to recognize these
complications could lead to erroneous
conclusions.

The location of abnormalities in the
head region, progessive response to
selection, variable penetrance and expressi-
vity, abnormalities in progeny of normal
appearing parents, and suggestion of
maternal effect are strikingly parallel to
the tumorous head condition in Droso-
phila melanogaster (Gardner & Ratty,
1952; Gardner & Woolf, 1949).

The phenomena observed in tentacle
variation inheritance in Biomphalaria

glabrata, and the fact that the inheritance
apparently has a multifactor basis, compli-
cate the use of the character as a genetic
marker. The information provided by
this inheritance, however, may be helpful
in studies on other characters in mollusks,
such as infectivity for various parasites
and resistance to chemical molluscicides.
Some of the snails with one tentacle
missing showed a tendency to circle in the
direction of the missirg tentacle. In
physiological studies it might be useful to
compare reactions to light, chemicals,
etc., of normal snails and snails with one
tentacle or one eye missing.

LITERATURE CITED

BOYCOTT, A. E. & DIVER, C., 1923, On the
inheritance of sinistrality in Limnaea peregra.
Proc. Roy. Soc. Lond. В, 95: 207-213.

CRABB, E. D., 1927, Genetic experiments with
pond snails Lymnaea and Physa. Amer.
Naturalist, 61: 54-67,

DAVIS, G. M., MOOSE, J. W. & WILLIAMS,
J. Е., 1965, Abnormal development in a hybrid
Oncomelania (Gastropoda; Hydrobiidae).
Malacologia, 2: 209-217.

GARDNER, E. J. & RATTY, F. J., 1952, Pene-
trance and expressivity of tumorous head in
Drosophila melanogaster and relative viability
of flies carrying tumorous head genes. Gene-
tics, 37: 49-61.

GARDNER, Е. J. & WOOLF, С. M., 1949,
Maternal effect involved in the inheritance of
abnormal growths in the head region of Dro-
sophila melanogaster. Genetics, 34: 573-85.

NEWTON, W. L., 1953, The inheritance of sus-
ceptibility to infection with Schistosoma mansoni
in Australorbis glabratus. Exp. Parasit., 2:
242-257.

NEWTON, W. L., 1954, Albinism in Austra-
lorbis glabratus. Proc. helminth. Soc. Wash.,
21: 72-74.

NEWTON, W. L., 1955, The establishment of a
strain of Australorbis glabratus which combines
albinism and high susceptibility to infection
with Schistosoma mansoni. J. Parasit. 41:
526-528.

RICHARDS, C. S., 1967, Genetic studies on
Biomphalaria glabrata (Basommatophora: Pla-
norbidae), a third pigmentation allele. Mala-
cologia, 5: 335-340.

RICHARDS, C. S., 1968, Aestivation of Biom-
phalaria glabrata (Basommatophora: Planor-

BIOMPHALARIA GLABRATA: GENETICS 527

bidae): Genetic studies. Malacologia, 7: WONG, L. W. & WAGNER, E. D., 1956, Some
109-116. effects of ultra-violet radiation on Oncomelania
STURTEVANT, A. H., 1923, Inheritance of nosophora and O. quadrasi, snail intermediate
direction of coiling in Limnaea. Science, 58: hosts of Schistosoma japonicum. Trans. Amer.
269-270. micro. Soc., 75: 204-210.
RESUME

GENETIQUE DE BIOMPHALARIA GLABRATA: VARIATIONS DES
TENTACUBPES EL DES YEUX

C.S. Richards

La selection, Pisolement et l’autofecondation pendant 7 generations de Biomphalaria
glabrata albinos, aboutit à l'augmentation progressive, jusqu’à une fréquence relative-
ment stable de 60% de descendants qui ont des variations du tentacule, ce qui indique
une hérédite multifactorielle. А ce niveau de fréquence les descendants de ces mol-
lusques, avec Ou sans variations du tentacule, montrent la méme fréquence du caractere,
се qui suggere une expressivité partielle. En croisant un albinos a variation tentaculaire
avec des individus normaux а yeux noirs et, plus tard, avec des individus normaux du
type sauvage de B. glabrata, on obtient des descendants post-F, d’albinos, comportant
des variations tentaculaires. Les descendants post-F, des hybrides d'yeux noirs et de
types sauvages sont tous normaux, mais lorsque ceux-ci sont autofecondes, plus de la
moitié donne naissance a des variations du tentacule. Ces résultats prouvent la trans-
mission génétique du caractere et suggerent une influence maternelle. Les croisements
révelent que les yeux sont impliqués aussi bien que les tentacules et que le caractere
montre de multiples aspects: doubles, branchus, courts, absents ou en saccule pour les
tentacules; doubles, absents ou déplacés pour les yeux.

RESUMEN

GENETICA DE BIOMPHALARIA GLABRATA: VARIACION EN
OJOS. У TENTACULOS

C.S. Richards

Selección, aislamiento у autofertilización a través de 7 generaciones de ejemplares
albinos de Biomphalaria glabrata, resultaron en un aumento progressivo hacia una pro-
genie estable, con frecuencia relativa de 60% con variaciones de tentáculos, indicando
factores hereditarios múltiples. A este nivel de frecuencia, la progenie de los caracoles
con о sin variación de tentáculo, mostraron la misma frecuencia del caracter, sugiriendo
penetración incompleta. Apareando un ejemplar albino de B. glabrata de tentáculo
variable, con uno de cepa normal de ojos negros, y más tarde con otra normal de tipo
silvestre, el resultado fué de F, caracoles albinos que incluían variaciones tentaculares.
La progenie FJ de la cruza de tipos de ojos negros con los de tipo silvestre pareció normal,
pero cuando estos individuos se autofertilizaron, más de la mitad produjeron descendientes
con variaciones en los tentáculos, y en ambas variaciones de ambas maneras: tentáculos
dobles, ramificados, cortos, ausentes о saculares; ojos dobles, ausentes, o desplazados,

338 CHARLES S. RICHARDS
АБСТРАКТ

ГЕНЕТИКА BIOMPHALARIA GLABRATA: ИЗМЕНЧИВОСТЬ
ШУПАЛЕЦ И ГЛАЗ

Ч. С. РИЧАРДС

Селекция, изоляция и самооплодотворение в течение 7 поколений альби-
носов Biomphalaria glabrata проявились в постепенном ‘увеличении (вплоть до
относительной стабильности около 60% частоты встречаемости) поколений с
изменчивостью щупалец. Это указывает на наличие полифакториальной насле-
дственности. При такой частоте встречаемости количество потомства и мол-
люсков, обладающих или не обладающих изменчивостью щупалец, имели одина-
ковую частоту встречаемости, что заставляет предполагать неполное прони-
кновение. Скрещивание штаммов альбиносов, имеющих изменчивость щупалец e
нормальными черноглазыми популяциями, а потом-с нормальными дикими попу-
ляциями В. glabrata, давали в последующем поколении F1 альбиносов, имевших
изменчивость щупалец. Последующее скрещивание из поколения Е} черногла-
зых с дикими формами дало нормальных с виду моллюсков, но когда эти пос-
ледние были смешаны, то более половины из них дали потомство с изменчи-
востью щупалец.

Эти результаты показали на генетическую передачу характера и предпо-
лагают наличие скрещивания. В результате последнего оказалось, что глаза
моллюсков, Также как и щупальца, охвачены изменчивостью, характер кото-
рой выражается весьма различно: щупальца были двойные, разветвленные,
короткие, мешковидные или вовсе отсутствовали; глаза-двойные, смещенные
или, их не было.

MALACOLOGIA, 1969, 9(2): 339-348

GENETIC STUDIES ON BIOMPHALARIA GLABRATA:

MANTLE

PIGMENTATION

Charles S. Richards

(With the technical assistance of James W. Merritt)

Laboratory of Parasitic Diseases, National Institutes of Health,
Bethesda, Maryland 20014, U.S.A.

ABSTRACT

Black mantle pigmentation in Biomphalaria glabrata was studied microscopically and

genetically.
to select for pigment variations.

were used as markers in crossing experiments.
Black mantle pigment granules occur in Biomphalaria glabrata in 2 general types of

distribution; diffuse, and in localized groups of cells forming discrete spots.

Self-fertilization of isolated snails through several generations was employed
The basic pigment types (wildty pe. blackeye and albino)

Selection

resulted in true breeding spotted and unspotted stocks.

Crosses between spotted and unspotted stock snails produced spotted Fys.

Although

albinos could not produce black pigment, they transmitted the character for spotted or

unspotted mantle.

Biomphalaria glabrata in collections
from various field localities shows a
considerable range of variation in patterns
of mantle pigmentation (Richards &
Ferguson, 1965). Little is known of the
roles of environmental conditions.
genetics, or both in this pigment variation.
Newton (1954) and Paraense (1956)
suggested that the pigment variation was
probably influenced by multifactorial
genetics. Mantle pigment patterns have
been used as characters in descriptions of
many planorbid snail species. It is perti-
nent from a systematic standpoint to
know to what extent these patterns are
stable or to what extent they vary within a
species such as B. glabrata.

The relative transparency of albino
Biomphalaria glabrata’ makes possible
observations in vivo of migration and
development of parasites, normal organ
development in the snail host, and patho-
logy in infected hosts. In experimental
studies where it is desired to compare
host-parasite relations in albino and
pigmented snails, it would be useful to

339

employ ‘ pigmented” strains in which
the mantle pigment was so restricted as to
permit in vivo observations. Such strains
would be of particular value in species in
which albinos are not available.

If mantle pigment pattern variation is
genetically determined, such visible
variation may be linked with physiological
factors such as susceptibility to parasite
infection. resistance to molluscicides,
etc. Observations of pigment variations
in the course of studies on estivation in
Biomphalaria glabrata (Richards, 1968)
led to the following studies.

METHODS

The albino (A) strain of Biomphalaria
glabrata developed by Newton (1955),
the blackeye (B) mutant of that albino
strain (Richards, 1967), and a wild type
strain (С) of the same origin as the
albino strain were used. Snails were
reared in 400 ml and 250 ml beakers with
Petri dish covers, and fed Romaine
lettuce. Selected young snails were isolat-

340 CHARLES S. RICHARDS

ALBINO

œ
un
u

SPOTTED BLACKEYE

UNSPOTTED WILD TYPE

SPOTTED WILD TYPE

BIOMPHALARIA GLABRATA: GENETICS 341

ed and reared to obtain progeny by self-
fertilization. Mature snails were mated
for one week and re-isolated to obtain
progeny by cross-fertilization.

RESULTS
Descriptions of black pigmentation

Pigment types of Biomphalaria glabrata
are shown diagrammatically in Fig. 1.
Albino B. glabrata lack black pigment
(Fig: 2); black eye snails (Figs. 3, 4)
have variable black mantle pigmentation
and pigmented eyes but are deficient in a
black pigmentation typical of wild type
strains in head and feot and mantle
collar; and wild type snails (Figs. 5, 6)
have black eyes, black pigmentation in
head and foot and manile collar (Fig.
7, 8) and variable black mantle pigmen-
tation. Black mantle pigmentation in
black eye and wild type snails is of 2
types; diffuse. background pigmentation
(Fig. 9): and discrete spots of varying size,
shape, and distribution (Figs. 10, 11).
Diffuse pigmentation is generally distri-
buted throughout the mantle in some
snails, restricted to limited areas ir some,
and absent in others. Pigment spots vary
from black to pale gray and are numerous
and distributed throughout the mantle
in some snails, range through decreasing
degrees of distribution to the condition
of a few spots over the kidney, and in
some snails are lacking.

Diffuse pigmented areas in Biomphalaria
glabrata show scattered. small, spherical,
black granules in epithelial cells (Fig. 9).
Similar-appearing black granules are
concentrated in groups of epithelial cells
to form pigment spots in the mantle
(Figs. 10, 11). Spots vary in shape:
round, irregularly shaped. elongate trans-

verse stripes, or coalescence of spots to
form large irregular pigmented areas
(Harry & Hubendick, 1964). In com-
pletely spotted snails, the spots are
typically evenly spaced but not in regular
rows. When spotting is incomplete;
absence of spots is first evident in the
mantle area to the left of the kidney, then
on the inner right side, the most consistent
areas to have spots being over the kidney
and on the mantle collar.

In the head and body and collar of
wild type snails the cells with concentrated
pigment granules are primarily in the
connective tissue area beneath the epithe-
lium (Fig. 8), and may be rather evenly
distributed among cells with few or no
pigment granules giving а peppered
appearance (Fig. 7).

Selection for diffuse black mantle pigmen-
tation

Selection failed to produce true breeding
strains for diffuse pigmentation. Strains
were obtained predominantly with and
predominantly lacking diffuse pigment.
These differences were not constant,
however, apparently being influenced by
other factors in addition to genetics.
Some snails developed diffuse mantle
pigment soon after hatching. In other
snails diffuse pigment was not evident in
juveniles but developed as they grew older.
In some snail clones from a single parent
by self-fertilization, individuals isolated
while young and reared singly remained
free of diffuse pigmentation while the
crowded snails not isolated developed
diffuse pigmentation.

Selection for spotted and unspotted mantle
strains by isolation and self-fertilization

Isolations of selected wild type snails

eee

BiG eats

Diagram of 5 pigment types in Biomphalaria glabrata. Figs. 2-6.

Photographs of 5

pigment types taken at 12x. Fig. 2, albino: Fig. 3, unspotted blackeye; Fig. 4, blackeye with spotted
mantle but deficient in black pigment in collar and body; Fig. 5, wild type with black pigment in collar
and body but lacking mantle spots: Fig. 6, spotted wild type.

342 CHARLES S. RICHARDS

FIGS. 7-11. Photomicrographs of В. glabrata taken at 1000 magnification. Fig. 7, Black pigment
granules in cells of head of wild type B. glabrata showing discontinuous distribution of pigment, giving
stippled or * peppered `` appearance; Fig. 8, Black granules in pigment cell in the sub-epithelial connective
tissues of the mantle collar of a wild type snail; rod-shaped bodies are golden-brown pigment grannules
occurring in all 5 pigment types; Fig. 9, Diffuse mantle pigmentation, showing scattered black granules,
occurring in some wild type and blackeye snails; white circular areas are nuclei of epithelial cells; Fig. 10,
Mantle spot in wild type snail, consisting of 4 epithelial cells with concentrated black pigment granules;
Fig. 11, two cells of mantle spot in blackeye snail, showing concentrated black granules and clear nuclei.

BIOMPHALARIA GLABRATA: GENETICS 343

Fons
a АА (5)
SELFING

SELFING
es POST-CROSS PROGENY ae CROSS PROGENY ST
/
I

5 es

CAS АА CF

EIG: 12.

through several generations resulted in 2
strains; one breeding true for extensive
spotting (S) (Fig. 6), the other unspotted
(0) (Fig. 5). The unspotted strain provid-
ed snails with almost as clear visibility
through the mantle as albinos. Occasion-
ally an individual т this strain developed a
few pale spots over the kidney.
similar blackeye strains (Figs.
derived by selection.

Two
3, 4) were

Transmission of spotted mantle pigmen-
tation by crossing (Fig. 12)

In selecting for spotted (S) and
unspotted (U) strains enough isolations
were followed in each generation to insure
inclusion of heterozygotes (CA) so that
albinos would be available.

Wild type snails from the S strain were
reared in isolation and allowed to
reproduce by self-fertilization. CAS
represents several such snails, producing
progeny in 3:1 phenotypic ratio (CS:A).
the C offspring being spotted. CAS was
then mated with AA(S), an albino from an

oo 1:3 SS
SELFING SELFING

en € / Oe à y
ie os CROSS PROGENY р POST CROSS PROGENY N

GS Ga)

He
-
a a.

TR AA(S) САЦ =

Composite diagram of crosses illustrating transmission of mantle pigment pattern.

S strain colony. After re-isolation both
CAS and AA(S) produced progeny in | : 1
phenotypic ratio (CS:A-). demonstrating
reciprocal cross-fertilization and with
the С offspring from both parents
spotted.

Wild type snails from the U strain were
reared in isolation and allowed to re-
produce by self-fertilization. CAU
represents several such snails, producing
progeny in 3 : | phenotypic ratio (CU:A-),
the C offspring being unspotted. CAU
was then mated with AA(U). an albino
from. а © strain colony:= After. re-
isolation both САЦ and AA(U) produced
progeny in | : | phenotypic ratio (CU A-),
demonstrating reciprocal cross-fertili-
zation and with the C offspring from both
parents unspotted. Totals counted from
5 such crosses were as follows: AA(U)
progeny 35CAU: 42АА, CAU progeny 50
CAU: 45 AA.

When a CAS was mated with an AA(U),
both CAS and AA(U) produced post-
cross progeny in 1:1 phenotypic ratio

344 CHARLES S. RICKARDS

ЕТ@. 15.

(CS:A-), the С offspring being spotted.
In some of such matings the AA(U) was
first mated with a CAU: one AA(U), for
example, producing post-cross progeny
16 CAU: Ш АА. After 6 weeks the
same AA(U) was mated with a CAS: the
AA(U) then producing post-cross progeny
26 CAS: 28AA.

When a CAU was mated with an AA(S)
both CAU and AA(S) produced post-
cross progeny in | : 1 phenotypic ratio
(CS:A-), the C offspring being spotted.
Totals counted from three such matings
were as follows: AA(S) progeny 39 CAS;
40 AA, CAU progeny 23 CAS: 17 AA.
In some of these matings, the CAU was
first mated with an AA(U), both parents
producing post-cross progeny 1:1 with
the С offspring unspotted. When the
same CAU was subsequently mated with
an AA(S), both parents produced post-
cross progeny |: 1 with the С offspring
spotted. One CAU produced no eggs by
self-fertilization, produced 14 CAU:14AA
after mating with an AA(U), and produced

BAS

SS SELFING

jes

POST-CROSS PROGENY

2:1:1

Sr e

Diagram of cross between unspotted wild type and spotted blackeye B. glabrata.

20 CAS: 13 AA after a subsequent mating
with an AA(S).

Inheritance of mantle spotting т
black-eye snails was similar to that in
wild type. When a CAU snail was
mated with BAS (a spotted black-eye
hybrid, Fig. 13), both parents produced
post-cross progeny in 2 : 1 : 1 phenotypic
ratios (2. CS: 1-BS: 1 AS) the С sands
offspring being spotted. For example a
CAU which produced 15 CAU: 5 AA by
selfiing was mated with a BAS which
produced 17 BAS: 3 AA by selfing.
After reisolation the CAU produced 14
CS: 6 BS: 8 AA; the BAS produced 14
©5::8 BS: SAA:

Segregation of mantle pigment types
following mixed crosses

When spotted progeny resulting from a
cross between S and U parents were
isolated they typically produced by self-
fertilization progeny in mixtures including
spotted (S), intermediate incompletely
spotted (1), and unspotted (U).

BIOMPHALARIA GLABRATA: GENETICS 345

DISCUSSION

Apparently age and environmental
conditions in addition to inheritance are
factors influencing development of diffuse
pigmentation.

Production of wild type and blackeye
strains either with or without spotted
mantle pigment by selection and inbreed-
ing (isolation and self-fertilization)
suggested inheritance of this character.
This is pertinent to the use of mantle
pigment patterns in taxonomic des-

criptions. Since several generations of

selection were required to establish such
strains, apparently inheritance involved
multiple factors. F, hybrids from a
mixed cross commonly produced progeny
varying from spotted to unspotted with

variable intermediate stages. Analysis of

tabulations of the variable pigment
patterns in such progeny did not readily
reveal information as to number of factors
involved and their interactions. It is
considered beyond the scope of the
current exploratory genetic studies to
pursue the statistical analysis of such
variable progeny.

Crosses demonstrated that the spotted
condition is dominant over unspotted.
When an unspotted hybrid wild type
(CAU) was mated with a spotted hybrid
blackeye (BAS). each snail produced
spotted post-cross progeny. The resulting
Dein ratios, with occurrence. of В
snails in post-cross progeny of the CAU
parent and C snails in post-cross progeny
of the BAS parent, demonstrated recipro-

cal cross-fertilization. Production of

post-cross spotted C and B offspring by
the unspotted CAU parent demonstrated
genetic transmission of the pigment pattern
character.

Production of post-cross unspotted
CAU progeny by AA(U) mated to CAU
and production of post-cross spotted CAS
progeny by the same AA(U) after a
subsequent mating with a CAS, again

demonstrated genetic transmission of the
pigment pattern character. Of particular
interest were the matings of either CAU
or BAU with AA(S) snails, resulting in
spotted post-cross CAS or BAS offspring
respectively by the unspotted parents.
This demenstrated that albino AA(S),
derived from heterozygous spotted strain
parents, carried and transmitted factors
for the spotted pigment pattern. while
lacking the ability to form black pigment
themselves.

Albino snails have proved of great value
in research. Albinism has served as a
genetic marker in systematic and other
studies. The transparency of albinos has
enabled in vivo observations of normal
organ development, pathology, and deve-
lopment and migration of parasites.
Mantle pigment in species other than
Biomphalaria glabrata probably has a
similar genetic basis. In species in which
albino strains are not available it might be
possible by selection to develop wild type
strains sufficiently deficient in pigment to
permit better in vivo observations of
internal phenomena. Lack of spotting,
even though having a multi-factor basis.
might also serve as a genetic marker at
least for one generation in experimental
studies.

The matings CAxBB ог CAxBA can
provide qualitative as well as quantitative
evidence of reciprocal cross-fertilization.
Reciprocal cross-fertilization is indicated
quantitatively but one-sided cross-fertili-
zation only qualitatively by progeny in
the following matings: CBxBB, CBxBA,
CBxAA, CAxAA, or ВАхАА. Only
one-sided cross-fertilization is demonstrat-
ed by the progeny in the following crosses:
CCxBB, CCxBA, CCxAA, or BBxAA.
Mantle pigment spotting provides quali-
tative indicators for reciprocal cross-
fertilization in ali the above matings if the
first mate listed is from an unspotted
strain and the second from a spotted
strain.

346 CHARLES S. RICHARDS

AA(U)

FIG. 14. Diagram illustrating use of pigmentation as marker in experimental multiple matings.

The value of Biomphalaria glabrata
as a molluscan genetic model was suggest-
ed in a previous paper (Richards. 1967).
Variability, capacity for reproduction by
self-fertilization through a consecutive
series of generations facilitating selection
for a particular character, dominance of
cross-fertilization when two snails are
associated together, return to self-fertili-
zation usually about 6 weeks after re-
isolation, and occurrence of 3 basic
pigment alleles (albino, blackeye, wild
type) were summarized. In experimental
studies it was possible to self an albino
and mate it as many as 4 times in sequence,
alternating blackeye and wild type mates,
and distinguishing the albino’s progeny as
to male parent. Incorporating mantle
spotting, an albino from an unspotted
strain can be mated in series as follows:
unspotted blackeye, unspotted wild type,
spotted blackeye, and spotted wild type
with reasonable assurance that progeny
from each mating can be distinguished
accurately. Furthermore, placing the
albino in association with 4 such mates

concurrently (Fig. 14) should provide
information on reproductive dynamics in
natural populatiors.

LITERATURE CITED

HARRY, Н. W. & HUBENDICK, B., 1964, The
freshwater pulmonate Mollusca of Puerto Rico.
Meddelawden Góteborgs Musei Zool, Ardelning,
136: 1-77.

NEWTON, W. L., 1954, Albinism in Australorbis
glabratus. Proc. Helminth. Soc. Wash., 21:
72-74.

NEWTON, W. L., 1955, The establishment of a
strain of Australorbis glabratus which combines
albinism and high susceptibility to infection with
Schistosoma mansoni. J. Parasit., 41: 526-528.

PARAENSE, W. L., 1956, A genetic approach to
the systematics of planorbid molluscs. Evolu-
tion, 10: 403—407.

RICHARDS, C. S., 1967, Genetic studies on
Biomphalaria glabrata (Basommatophora: Pla-
norbidae), a third pigmentation allele. Mala-
cologia, 5: 335-340.

RICHARDS, C. S., 1968, Aestivation of Biom-
phalaria glabrata (Basommatophora: Planor-
bidae): Genetic studies.
109-116.

RICHARDS, С..5. & FERGUSON, Е. F., 1965,
Variability in Australorbis glabratus (Say).
Trans. Amer. microsc. Soc., 84: 580-587.

Malacologia, 7:

BIOMPHALARIA GLABRATA: GENETICS

RESUME

ETUDES GENETIQUES SUR BIOMPHALARIA GLABRATA:
PIGMENTATION DU MANTEAU

C.S. Richards

La pigmentation noire du manteau chez Biomphalaria glabrata a été étudiée en micro-
scopie et en génétique. On a utilisé Pautofécondation d'individus isolés pendant
plusieurs générations, comme méthode de sélection pour les variations pigmentaires.
Les types pigmentaires de base (type sauvage, yeux noirs et albinos) ont été utilisés
comme références dans les expériences de croisements.

Les granules pigmentaires noirs du manteau existent chez Biomphalaria glabrata sous
deux formes de distribution; diffus et localisés par groupes de cellules formant de discretes
ponctuations. La sélection aboutit a des lignées pures ponctuées et non ponctuées.

Les croisements entre lignées ponctuées et non ponctuées produit des générations F,
ponctuées. Bien que les albinos ne puissent pas produire du pigment noir, ils
transmettent le caractére de manteau ponctué ou non-ponctué.

RESUMEN

ESTUDIOS GENETICOS EN BIOMPHALARIA GLABRATA:
PIGMENTACION DEL MANTO

C.S. Richards

Se estudio, microscópica y genéticamente, la pigmentación negra del manto de
Biomphalaria glabrata. Para variaciones de pigmento se seleccionaron individuos—
aislados por varias generaciones-, por autofertilización. Tipos básicos de pigmento,
(silvestre, ojo negro, albino), se usaron como testigos en los experimentos de
cruzamientos.

Gránulos de pigmento paleal negro aparecen en Biomphalaria glabrata en dos tipos de
distribución general: difusos, y en grópos de células localizadas formando discretas
manchas. La selección resultó en linajes con y sin manchas.

Cruza entre esos linajes, manchados у no manchados, produjeron Fy, manchados.
Aunque los albinos no pueden producir pigmento negro, transmitieron el caracter de
mantos manchados v no manchados.

347

348 - ‘CHARLES 5. RICHARDS:

ABCTPAKT

ГЕНЕТИЧЕСКИЕ ИССЛЕДОВАНИЯ BIOMPHALARIA GLABRATA:
ПИГМЕНТАЦИЯ МАНТИИ.

Ч. ©. Ричардс

Черная пигментация мантии у Biomphalaria glabrata изучалась микроскопи-
чески и генетически. Для отбора пигментных вариаций использовалось само-
оплодотворение в течение нескольких поколений у изолированных моллюсков.
Основные типы пигментированных особей (дикие, черноглазые и альбиносы)
использовались как обладатели сигнальных генов в опытах по перекрестному
оплодотворению. Гранулы черного мантийного пигмента встречаются y
В. glabrata среди особей двух главных типов распространения; диффузные и
локализованные группы клеток могут образовывать дискретные пятна. В ре-
зультате селекции у гомозиготных форм получены пятнистые и неокрашенные
популяции.

Скрещивание пятнистых и неокрашенных Форм дают пятнистых Fy. Хотя
альбиносы и не могут образовывать черный пигмент, они передают основу
для форм пятнистой и неокрашенной мантий.

MALACOLOGIA, 1969, 9(2): 349-389

THE COMPARATIVE EMBRYOGENESIS AND EARLY
ORGANOGENESIS OF BURSA CORRUGATA PERRY AND
DISTORSIO CLATHRATA LAMARCK (GASTROPODA:
PROSOBRANCHIA)!

Charles N. D'Asaro?

Institute of Marine Sciences
University of Miami
Miami, Florida, U.S.A.

ABSTRACT

Due to their close relationship at the familial level, a comparative study of develop-
ment in Bursa corrugata and Distorsio clathrata can demonstrate certain dissimilarities
in ontogeny which are indicative of adaptability at the larval level. To achieve this goal,
the following data are presented. Breeding, spawning and the structure of the egg
capsules are described. Embryogenesis, including development to the Ist torsional
stage, is outlined. Organogenesis is traced from the torsional pause through the end
of the Ist planktotrophic veliger stage which coincides with diverticulation of the left
digestive gland.

In summary, the taxonomic characters of the Ist veliger stage are outlined and the
gradual change of larval characters with time is noted. Trends in the development of
the long-term planktotrophic species leading to natatorial independence are discussed
in relation to the organ systems involved. Ontogenetic variations which are examined
include the formation of polar lobes, some aspects of torsion, the methods of larval
nutrition and the sculpture of the protoconch.

CONTENTS
PAGE
MPEINDRODUEHON ое... 350
МЕТ О, оне 95
ITEBURSAZLCORRUGATA == o e at 39
1. Breeding habits, spawning and egg сар-
sule.morphology еее 351
Pe Embryogenesis ее .... 355
Sm OroanOsenesisas ее 361
IV. DISTORSIO СЕАТНКАТА ....... 368
1. Breeding habits, spawning and egg cap-
sule-morphology” =. п... 2 4... 368

PAGE
2 SEmbryOgenesis: 22.20... ae 30
Bee OrpanOPenesisy 2 A so aes ees ЗА
у ом... OZ

1. Taxonomic characters of the first veliger
SAGE eee oe a dee Sinn a vies nor OOS

2. Development of natatorial inde-
pendence 3 un an 38

3. Ontogenetic variations and their signi-
MICANCE Are 2 sr ee te 384
ACKNOWLEDGMENTS .......... 386

LITERATURE CITED: : „+... 4 +: 386

1 Contribution No. 1172 from the Institute of Marine Sciences, University of Miami. This article is part
of a dissertation submitted in partial fulfilment of the requirements for the degree of Doctor of Philo-
sophy at the University of Miami, Miami, Florida, U.S.A. The investigation was in part conducted
under the auspices of the U.S. Public Health Service (GM 125-41-02).

2 Present address: Department of Biology and Marine Science, The University of West Florida, Pen-

sacola, Florida 32504, U,S.A.

350 CHARLES N. D’ASARO

I. INTRODUCTION

The Prosobranchia comprises the largest
subclass of the Gastropoda and contains
some of the most successful marine animals
in terms of ability to exploit diverse
habitats. Of nearly 40,000 extant species
of marine gastropods (Abbott, 1954),
approximately 25,000 are prosobranchs
(Schilder, 1947). Considering the size,
availability and significance of the group,
it is unfortunate that the developmental
history (or any part of it) is known for less
than 1% of the species. As pointed out
by Anderson (1960), most observations
have been limited to temperate North
American and European species. If one
examines this body of work, it becomes
evident that the bulk of descriptive
investigation is concentrated in 4 principal
areas, mentioned briefly below. Studies
of reproductive habits and egg capsules
with cursory examination of the embryos
are mostcommon. Even in an intensively
studied region like the British Isles, the
basic data on reproduction are unknown
for almost half of the species listed in
Fretter & Graham (1962). The 2nd area
of investigation, which is concerned with
cleavage and cell lineage, is the result of
monumental works by Patten (1886),
Conklin (1897) and others. Unfortunate-
ly, most of this work is limited to primitive
species. The 3rd segment includes
moderately detailed observations on cap-
sulated and some free-living stages.
Pelseneer (1911) and Fioroni (1966a)
provided the best examples of this work
because they compared several different
species. Lebour’s work (especially 1937
and 1945) and Thorson’s (1946) are
examples of general developmental studies
which point out the important stages.
The 4th area, which includes the most
complete work on the development of
prosobranchs, is usually limited to studies
of the primitive archeogastropods and
species with direct development. As

pointed out by Fretter & Graham (1962)
for the British species, the later develop-
mental stages have been followed in
adequate detail only in Patella, Haliotis,
Viviparus and Pomatias. On a world-
wide basis some species of Littorina,
Crepidula, Thais and Nassa can be included
in this group.

Developmental information on tropical
species is extremely sparse. Most papers
are concerned with describing egg capsules
and include only cursory embryological
observations. Typical examples are
Thorson’s (1940) studies on the egg masses
and larval development of gastropods
from the Iranian Gulf, Knudsen’s (1950)
review of spawning and development
in marine prosobranchs from tropical
West Africa, Ostergaard’s (1950) obser-
vations on the egg capsules of Hawaiian
marine gastropods and Kohn’s (1961)
account of spawning’ behavior, egg
masses and larval development т
Conus from the Indian Ocean. A
complete description of embryogenesis
and organogenesis has not been
compiled for a single tropical marine
prosobranch.

After considering the past approach to
studies of prosobranch development, it is
necessary to outline the aims of this
research in light of the introductory
remarks. First, south temperate and
tropical species have been selected to
provide regional data. Second, as in the
earlier work, detailed studies of undes-
cribed egg masses have been made.
Third, basic outlines of major embryo-
genetic and organogenetic changes have
been completed for comparative purposes.
Fourth, some taxonomic characters of the
veliger stages have been described to aid
the planktonologist. In contrast to much
of the previous work, developmental data
have been based on serial sections and
illustrated by detailed drawings. Finally,
the major divergences between the 2
ontogenies have been examined,

EMBRYOGENESIS AND ORGANOGENESIS 351

The Ist species described here is Bursa
corrugata Perry (=caelata Borderip). Most
contributions to the knowledge of bursid
life histories are limited to descriptions
of egg capsules with short notes on the
enclosed embryos. Petit & Risbec (1929)
and Risbec (1931) published figures of egg
capsules from Ranella(=Bursa) gyrina and
Ranella (=Bursa) granifera with some
comments on the contents. Data on B.
spinosa, including figures of the egg mass,
egg capsules and an embryo during the
early stages of larval kidney formation,
were provided by Thorson (1940).
Abbott (1954) included a photograph of
the egg mass of В. californica. Fioroni
(1966 a, b) reviewed some aspects of the
development of an unidentified bursid with
nutrient eggs. The egg mass of B.
granularis, as described and illustrated by
Cernohorsky (1967), differs radically from
other known egg masses of this genus in
having the capsules completely embedded
in a gelatinous matrix.

The 2nd species described in this study
is Distorsio clathrata, about which little
was previously known. The reproductive
habits, egg capsules and larval stages of
D. clathrata have not been previously
described.

|. METHODS

The histological methods employed
follow those used by D’Asaro (1965,
1966). Somewhat better results are
obtained by sectioning at 8 microns.

Rearing methods for the larval stages
are relatively simple and also follow the
methods suggested by D’Asaro (op. cit.).
Although both Florida Current water and
water collected daily at high tide from
Bear Cut (near Miami, Florida) were used
in culture, the former was most suitable
for both species. Algal foods came from
2 sources, the partially filtered water and
added supplementary food. Platymonas
sp., Dunaliella tertiolecta and Chlorella

sp. (alone and in combinations) at concen-
trations less than 8,000 cells/ml were
used as supplementary foods for both
Bursa corrugata and Distorsio clathrata,
with only partially successful results.
Bursa remained active for 20 days and
Distorsio for 16 days.

lilustrations were prepared by com-
paring tracings of photo-micrographs with
freehand drawings of the same individual.
Most figures, especially those of later
stages, were drawn as semi-transparent
objects with some organs outlined as they
appear in optical section.

Ш. BURSA CORRUGATA

1. Breeding Habits, Spawning and Egg

Capsule Morphology

Bursa corrugata is a relatively rare
species on the southeast coast of Florida
and in the Caribbean Sea; however, it
becomes more common on the Pacific
coast between Lower California and
Ecuador (Abbott, 1954). All egg capsules
were obtained from captive individuals
collected in the Pacific region. These
collections were made by Dr. F. M.
Bayer of the Institute of Marine Science.
University of Miami, from Perico Island
in the Gulf of Panama at varying intervals
from 1963 through 1965.

Populations of mixed sexes were kept
in aquaria with running sea water and fed
the bivalves, Chione cancellata, Codakia
orbicularis and Cardita floridana. An
abundance of food after several weeks of
starvation usually produced spawning.
Oviposition under these conditions occurs
only between October and May. Certain
individuals maintained this pattern for
three consecutive breeding seasons. A
female may spawn several times each
season.

Copulation occurs from several hours
to a week before oviposition. Egg cap-
sules were deposited only in corners of the
aquaria on slate or glass, No attempt was

352 CHARLES N.

Cade to test substrate preferences.
mommunal spawning was not observed
and the presence of egg capsules did not
appear to induce oviposition. Each female
broods her egg mass until hatching begins.

After oviposition, the egg mass
undergoes a series of color variations
caused by embryonic development and
not by changes in the transparent and
colorless capsular membranes. Freshly
laid, white capsules gradually become
yellowish-white т 4 days. Those capsules
which remain white contain either sterile
or decaying eggs. Between the 8th and
9th day a granular. brown color appears
and increases in intensity until hatching
occurs. This pigment is produced by
the shell gland and isolated in the proto-
conch. Color changes are uneven, begin-
ning with older capsules and gradually
spreading over the whole mass.

A typical egg mass is roughly oval,
slighly concave and matches the outline of
the female’s aperture. The capsules
incline toward the center (Fig. IA). A
cross section at the capsular base above
the stalk has roughly the shape of an
obtuse triangle with the obtuse angle
facing the periphery of the mass (Fig. 3A).
Opposite this angle, the wall is convex,
while the walls forming the sides of the
angle are either straight or slightly concave.
This configuration allows each capsule to
fit tightly against those in the preceeding
row. There is some evidence that a
female can control the shape of a capsule.
During oviposition, aberrations in the
normal pattern are corrected by changing
the gross outline of several capsules thus
re-establishing the positional relationship.
The basal membrane, which cements the
egg mass to the substrate, is composed of
uneven segments. Each basal segment is
attached by its central margin to the
convex side of an egg capsule (Figs.
1B-1C). Lateral ribs originate at both
ends of the basal connecting segment and
radiate toward the apex.

D’ASARO

FIG. 1. Egg capsules of Bursa corrugata
A, a typical egg mass (apical view); B, central
egg capsule (lateral view); C, peripheral egg
capsule (view of the peripheral side).

Capsular walls have a typical three-
layered construction which Amio (1963)
has shown to be characteristic of highly
evolved mesogastropods. The outer
layer is rugose at the apex, especially in
the vicinity of the escape aperture, and
smooth over the remainder of the capsule
and the basal segment. The middle
layer is spongy and fibrous. Distinctively,
the inner layer does not extend into the
stalk or basal segment. It is similar in
appearance to the middle layer; however,
it takes a darker stain. No preformed,
escape-aperture plug is present. In place
of the plug there is a flaw in the fibrous
texture of the membranes associated with
an external lengthwise fold.

The number of capsules per mass from a
sample of 5 ranged from 110 to 150.
Quantitative variations are due to the
size of the body whorl because each female
produces only as many capsules as she can
cover with the aperture during brooding.
In the breeding population under exami-

EMBRYOGENESIS AND ORGANOGENESIS

nation, the width of the aperture between
the medial lip and the columella ranged

from 16 to 25 mm. Egg masses produced

by these individuals had corresponding
diameters between 14 and 25 mm. The
total number of capsules may increase

KEY TO ABBREVIATIONS

archenteron
albumen

albumen cell

anal duct

adult heart

adult kidney

anlage of the left digestive gland
anal cell

apical plate

animal pole

apical sensory region
blastopore

beak line

basement membrane
columella

carina

cerebral commissure
concave side
cerebral ganglion
chamber

coriaceous layer
columellar muscle
cephalic region
cephalic sinus
convex side

central yolk mass
deutoplasm
digestive anlage
diverticulum

dorsal mantle lip
dorsal extension of the pretorsional shell
gland

esophagus

escape aperture
ectodermal cells

egg capsule
excretory granule
embryo

food groove

fibrous layer
food-storage region
growth line
glandular cells
gastric lumen
gastric shield
hypobranchial gland
intestine

left digestive duct
left digestive gland
luminal fissure
larval heart

larval kidney

plg

longitudinal ridge
myoblast

mantle anlage

mantle cavity
metapodial ganglion
micromeres
membranous layer
metapodial node
mouth

mesopodial lobe
metapodial sensory lobe
operculum

osphradial ganglion
osphradial invagination
optic vesicle

proctodeum

pedal anlage

pallial lobe

pallial sinus
protoconch
peripheral side

pedal ganglion

polar lobe

pleural ganglion
pallial secretory cells
posterior ciliary band
propodium

preoral ciliary band
protostyle

pedal sinus
peripheral storage cells
prototroch
renopericardial anlage
right digestive gland
right tentacle
stomodeum

site of the blastopore
segmentation cavity
supra-esophageal ganglion
shell gland
stomodeal plug
style-sac stomach
statocyst

stomach

typhlosole

vacuole

vacuolated cell
visceral ganglion
velar lobe

velar sinus

visceral sinus

354 CHARLES N. D’ASARO

FIG. 2. Development of Bursa corrugata: A, an egg at oviposition; В, extrusion of the Ist polar lobe;
C, Ist polar body with the polar lobe at apogee; D, retraction of the Ist polar lobe; E, 2nd polar body;
Е, extrusion of the 2nd polar lobe; С, onset of the Ist cleavage; H, completion of the Ist cleavage plane;
I, retraction of the 2nd polar lobe; J, complete 2-cell stage; K, extrusion of the 3rd polar lobe; L, vegetal
view of the 3rd polar lobe at the onset of CD cleavage; M, vegetal view of early AB cleavage; N, retraction
of the 3rd polar lobe by D; O, 3rd cleavage; P, late cleavage stage with a prominent vegetal blastomere.

EMBRYOGENESIS AND ORGANOGENESIS 355

when oviposition occurs in а crevice
because the egg mass is molded to
conform with the irregularities of the
substrate.

The dimensions of a capsule vary with
its position in the egg mass. This
relationship was also shown in Bursa
spinosa (Thorson, 1940). The central
capsules are taller and narrower at the
base than the peripheral ones (Figs. 1B-
IC). Both types are roughly pyramidal
in Outline with rounded edges. In egg
masses which have been produced on
flat substrates, differentiation between the
2 types is reduced. The average dimen-
sions from a sample of 10 central capsules
are: length-5°5 mm, width at the base-
2°3. For 10 peripheral capstles the
average measurements are: length-3°4 mm.
width at the base-3°0 mm.

Positional variations in capsular size are
reflected by their contents. The average
number of embryos in the previously
measured central capsules was 900. Peri-
pheral capsules contained an average of
600. Since approximately a 4 to |
ratio exists between the number of central
and peripheral capsules, an estimate of the
total number of embryos per mass can be
made. The smallest examined contained
approximately 92,000 and the largest
115,000.

2. Embryogenesis

Bursa corrugata is a dioecious species
with internal fertilization. The exact site
of fertilization was not determined, bnt as
demonstrated in the Gastropoda by Y onge
(1960), it is probably in the medial oviduct
close to the albumen gland.

Maturation is characterized by well
defined polar lobes similar to those found
in the scaphopods, pelecypods and gastro-
pods listed by Raven (1958). The first
external evidence of plasmic reorganization
is present 1 hour after oviposition. In 2
hours, the ptimary polar lope reaches its
apogee concurrently with production of

the first polar body (Figs. 2A-2C). А
steady reabsorption of the lobe occurs
during the second stage of maturation
culminating in production of the second
polar body concurrently with total absor-
otion of the primary lobe (Figs. 2D-2E).
This process is completed in about 3
hours at 24°C. All polar lobes contain
granular cytoplasm and have few or no
yolk granules. a condition similar to
another tonnacean, Argobuccinum oregon-
ense (Phillpott, 5192).

Formation of the secondary polar lobe
which reaches its maximum size when the
first longitudinal cleavage plane appears,
marks the onset of cleavage (Figs. 2F-
2G). A distinct “ trefoil ” stage develops
when the cleavage plane separates AB
from CD leaving the polar lobe associated
with the CD blastomere. The secondary
polar lobe is then absorbed by CD forming
the 2 celled stage (Figs. 2H-2J). Further
cleavage is irregular and differs somewhat
from the so-called normal pattern of
spiral cleavage. Prior to formation of the
4 cell stage, a tertiary polar lobe develops
vegetally on the CD blastomere. When
this lobe reaches its greatest magnitude, a
longitudinal cleavage plane begins to
divide CD. The polar lobe is retained on
the D blastomere (Figs. 2K-2M). Both C
and D blastomeres are completed before
the cleavage of AB begins. When A and
B are distinct the tertiary polar lobe is
reabsorbed producing a D blastomere
slightly larger than the other blastomeres
(Fig. 2N).

Cleavage rates affecting the 8 cell stage
are unequal. Dextral formation of la-lb
is completed before Ic-ld (Fig. 2 О).
Similar inequalities are common in
succeeding stages. Since cleavage is not
followed in detail beyond this point, it
is not possible to identify the prominent
blastomere located at the vegetal pole in
later stages (Fig. 2P). A typical stereo-
blastula is present prior to gastrulation
(Fig. 3B).

356 CHARLES N.

D’ASARO

FIG. 3. Development of Bursa corrugata: A, cross-section of an egg capsule; B, cross-section of a stereo-
gastrula (4 days); C, parasagittal section through the stomodeum (5 days); D, frontal section through the
archenteron (8 days); E, parasagittal section through the invagination of the shell gland (8 days).

Four Days.—Gastrulation, beginning
shortly after completion of the 64-cell
stage, produces an early stereogastrula
similar to that of Crepidula fornicata
(Conklin, 1897). Epibolic growth con-
tinues to extend the cap of micromeres
around the macromeres toward the vegetal
pole. Extremely rapid proliferation by
the descendants of 2d forms a recognizable

shell gland anlage.

Five Days.—The major part of epibolic
gastrulation is completed during the early
fifth day when the macromeres are
completely enclosed by micromeres. A
prominent shell gland with an expanded
margin is present (Figs. 3C & 4A). The
posterior region associated with the shell
gland is characteristically flattened.

EMBRYOGENESIS AND ORGANOGENESIS 357

FIG: 4. Development of Bursa corrugata: A, dorsal view of the primordial shell gland stage (5 days);
B, ventral view of the stomodeal invagination (5 days); C, left side during the stomodeal invagination
(5 days); D, ventral view during the early stages Of larval kidney formation (6 days); E, ventral view during
formation of the prototroch (7 days); Е, right side during formation of the proctodeum (7 days).

358 CHARLES N. D’ASARO

FIG. 5. Development of Bursa corrugata: A, frontal section through the stomodeum and archenteron
(8 days); B, parasagittal section through the cephalic sinus (8 days); C, sagittal section through the eso-
phagus and digestive anlage (9 days); D, frontal section through the digestive anlage (9 days); E, oblique
section through cephalic and pedal regions in the plane of the major ganglia (10 days); F, parasagittal
section through the osphradial invagination (11 days).

Apical sensory development is limited to process at the site of the blastopore
an undifferentiated cap of cells. Near produces an unusually wide stomodeum
the end of the fifth day, an invaginatory surrounded by alip of transparent ectoder-

EMBRYOGENESIS AND ORGANOGENESIS 359

mal cells (Fig. 4B). A pedal anlage
forms posterior the stomodeum. Two
anal cells mark the future site of the
proctodeum (Fig. 4C). Mesodermal rudi-
ments can be identified at this time.

Six Days.—The appearance of extensive
ciliation and resulting motility are charac-
teristic of this period. Conspicuous cilia
line the dorsal and ventral lips of the shell
gland, the whole pretrochal region and
the stomodeum. The trochoblasts remain
unciliated.

Blastocoelic and archenteric cavities
are absent during early embryogenesis.
In later stages, certain blood sinuses
appear which are homologous with the
blastocoel of other species. The archen-
teric region is gradually outlined by a
layer of smaller deutoplasmic macromeres,
which make up the walls of the digestive
anlage, surrounding the larger deuto-
plasmic macromeres of the central yolk
mass. The diameter of the stomodeum is
reduced concurrently with the formation
of the archenteric wall. The anlagen of
the larval kidneys develop laterally just
anterior to the lip of the shell gland (Fig.
4D).

Two major sets of growth vectors begin
to change the shape of the embryo. The
first, which shifts the anal cells ventrally
and the larval kidneys anteriorly, is a
process of ventral flexion induced by
expansion of the trunk region. A 2nd
set of growth vectors, associated with
flexion, lengthens the embryo, especially
in the pretrochal and pleural regions
(Fig. 4E). This process continues until
protoconch formation and torsion begin.

Seven Days.—Major components of

several organ systems appear following
the beginning of differential growth.
Yolky material is separated into 2 distinct
areas; the gastric food-storage region,

which is diffused through the walls of

the digestive anlage, and the central yolk
mass (Figs. 3D & SA). Between the pedal
anlage and the lip of the shell gland.

there is a narrow, proctodeal invagination
touching the archenteric wall (Fig. 4F).
The stomodeum continues to decrease in
diameter and becomes roughly rectangular
in outline. Its junction with the archen-
teron 1$ still closed.

In the pretrochal region, 3 sinuses,
which are homologous with a blastocoel,
appear. The cephalic sinus develops
under the apical cap anterior to the
stomodeum, while the velar sinuses expand
dorsal and lateral to the stomodeum
(Figs. 4F & 5B). Formation of the
sinuses is the result of anteriorly directed
growth processes and delamination.
Shortly after the appearance of the
cephalic sinus, cerebral ganglia proliferate
from the cephalic plates. Ciliation is
now specialized. The apical sensory
region has short, stout cilia which extend
ventrally in a wide band to the stomodeal
lip. The velar region has very fine cilia
and a row of enlarged, dorsal trochoblasts.
Prototrochal ciliation appears first on
these cells. Specialized stomodeal and
pedal ciliation associated with the feeding
mechanism 1$ present.

Eight Days.—Pretrochal developments
are coupled with further expansion of the
velar and cephalic sinuses. А cerebral
commissure, which ts later invaded by
nerve fibers, develops Бу proliferation
of ectodermal cells between the ganglia
(Fig. 6A). There is a non-ciliated area
separating the prototroch and apical
sensory region.

Posttrochally, a conspicuous expansion
and thickening in the trunk region marks
the beginning of the major phase of shell
gland development. Only a slight invagi-
nation precedes growth (Fig. 3E). The
principal growth vectors are dorsally
oriented. Further expansion of the larval
kidneys surpasses and obscures the support
cells. Fioroni (1966a, b) presented detail-
ed drawings of larval kidneys in a bursid
which are equivalent to those of Bursa

corrugata at the 8th day. Expansion of

360 CHARLES N. D’ASARO

Ik pt

FIG. 6. Development of Bursa corrugata: A, ventral view at the beginning of formation of ganglia
(8 days); B, right side during expansion of the shell gland (8 days); C, left side of a pretorsional veliger
(9 days); D, dorsal view at the beginning of the Ist stage of torsion (9 days).

the pedal and visceral sinuses begins
(Fig. 6B).

Nine Days.—This period can be divided
into 2 parts; (a) the completion of pretor-
sional growth: and (b) the first stage of
torsion. Prior to torsion, the combined

effect of the major growth vectors already
mentioned produces a typical early veliger
(Figs. 5C-5D & 6C). The head-foot
region is now distinct due to expansion of
the various sinuses and ectodermal differ-
entiation. Lateral, pedal invaginations

EMBRYOGENESIS AND ORGANOGENESIS 361

produce the statocysts. Statolith
formation begins shortly after invagi-
nation. In the visceral region. the
prominent dorsal process of the shell gland
is enlarged by expansion of the visceral
sinus. Mesodermal elements consoli-
dating in this sinus produce the columellar
muscle. Prior to torsion, its origin is
located in the dorsal process of the
rudimentary protoconch. Insertions are
primarily on the left ventral side with a
major subesophageal branch to the right
side. Other mesodermal elements consol-
idate into the renopericardial anlage.
Secretion of a conchiolinous matrix, which
began during the 8th day, produces a
pustulate, reddish-brown protoconch.
Considerable expansion of the
pretor- sional, dorsal mantle Пр takes
place.

The first stage of torsion shifts the
dorsal process of the shell gland 90 degrees
to the left (Figs. 6D & 8A). This shift
involves an elapsed time in excess of
24 hours. The probable, but not
confirmed, first stage effector is a right
larval retractor. Following the first
stage there is a pause, the interval of
which varies with the culture method and
temperature. It may be as short as |
day or as long as 5 days. The final stage
of torsion is completed somewhat faster
than the first. During the second stage,
the columellar muscle is prominent (Figs.
7A-7B). If differential growth, associated
with the formation of the columellar
muscle, is the primary cause of the second
stage of torsion, it can be only partially
applied to the process in Bursa corrugata
because а well developed columellar
muscle is present before the second stage
begins. Total torsional movement is
slightly less than 180 degrees.

3. Organogenesis

Ten Days.—Prior to this stage embryo-
genesis has been limited to specific,
isolated structures. During the torsional

pause the veliger becomes increasingly
systematized. In the nervous system,
the pleural ganglia, which are the 3rd
major pair, arise from lateral, ectodermal
proliferations in the pleural grooves. The
ganglia of the visceral loop are not identi-
fiable, but some type of anlage must be
present in each case at this time.
Connective formation is the result of
fibrous, interconnecting outgrowths of
the respective ganglia. Cerebropleural
connectives develop first. Both the
cerebral and pedal commissures are narrow
bands of cells closely associated with the
ectoderm. The tentacular nerves extend-
ing from the cephalic ganglia to the
tentacular anlagen function as accessory
connectives. Other sensory structures
include the optic vesicles, which appear as
invaginations on the cerebral plate lateral
to the cerebral ganglia (Figs. SE & 8A),
and the tentacular anlagen bordering the
apical sensory region. The _ vesicles
remain open until the end of torsion.
Prior to closing, black retinal pigment
develops in each vesicle.

In the digestive system, the anterior
portion of the gastric stomach is well
defined. А gastric lumen is present.
During the torsional pause, the unmodi-
fied intestine is located on the ventral right
side. The anlage of the left digestive
gland appears as a swelling on the visceral
mass.

Initially, circulation and blood pressure
are maintained by myoblasts found in all
body sinuses (Figs. 7A-7B & 7D) and
circular muscles below the ectodermal
layers. Contraction by these muscles
shifts fluids back and forth between the
sinuses providing rudimentary circulation
before the larval heart develops. The
increase in body size is mainly a product
of sinusoidal expansion, a process which
involves transport of fluids from the
surrounding medium into the rudimentary
circulatory system and ectodermal expan-
sion. This process, which began much

362 CHARLES N. D’ASARO

FIG. 7. Development of Bursa corrugata: A, frontal section through the columellar muscle (10 days);
В, frontal section through the anlage of the digestive gland (11 days); С, oblique section through the
intestine and the anlage of the digestive gland (12 days); D, parasagittal section through the foot and

visceral mass (13 days).

earlier, enters its most active stage during
expansion of the velar lobes (Fig. 8B).
Certain myoblasts also function as acces-
sory retractors for specific organs.

The torsional pause marks the point of
greatest expansion by the larval kidneys
(Figs. 8A-8C). These organs are now

more granular in appearance and contain
large vacuolated regions. Subsequent
development produces a gradual decrease
in size and finally complete absorption in
the post-hatching stages.

Pretrochally, the velar lobes begin to
expand while a concomitant increase in

EMBRYOGENESIS

AND ORGANOGENESIS 363

FIG. 8. Development of Bursa corrugata: A, ventral view during the torsional pause (10 days); B, right
side during the torsional pause (10 days); C, ventral view at the beginning of the 2nd stage of torsion
(11 days); D, left side of an early post-torsional veliger (12 days).

velar ciliation, producing the rudimentary
food grooves, takes place. In the pedal
region the posterior ectoderm of the foot
differentiates into an opercular gland,
which immediately secretes a thin, mem-

branous operculum. In the visceral
region, the cap-like shell gland expands ata
uniform rate surrounding the digestive
anlage. Before the enveloping process is
completed, there is a change in the

364 CHARLES N. D’ASARO

sculpture of the protoconch. Plate-like
structures appear, especially in the region
close to the mantle lip, concurrently with
an increase in the intensity of pigmentation.
Similar structures have been reported
from other tonnaceans (Amio, 1963,
Thorson, 1940).

Eleven Days.—The 11th day is marked
by the beginning of 2 important processes;
(1), the absorption of nutrient material
by specialized peripheral cells in the
anlage of the left digestive gland and (2),
the ascension of the dorsal, mantle lip
with the concomitant appearance of the
mantle cavity. Prior to the onset of the
second torsional stage, there is a sudden
increase in the size of certain peripheral
cells. These cells become very prominent
and sharply outlined in the living veliger
(Figs. 8B-8D). Anderson (1959) and
Fioroni (1966a, b) found similar cells in
other tonnaceans. Cell expansion begins
shortly before the esophagus is complete
and functional. Initially, there is a
gradual disintegration of archenteric yolk
from the macromeres followed Бу
absorption and possible phagocytic
ingestion of the fragments by the peri-
pheral cells. These cells appear in the
left digestive anlage and spread laterally
to the edge of the stomach anlagen.
Lateral expansion continues until the
posterior wall of the visceral mass 1$
tightly packed with a single layer of these
extremely large cells (Figs. 5C-5D, 7A-7D).
Before the process of absorption 1$
complete the esophagus opens allowing the
veliger to swallow capsular — fluids.
Although these fluids are somewhat
viscous there is no evidence proving
ingestion. However, the peripheral cells
are in the same position as albumen
ingesting cells in other species, have a
similar origin, function and ultimate fate
and, therefore, are homologous.

Formation of the mantle skirt also
begins prior to the second stage of torsion.
The process is quite similar to velar

expansion. When the mantle lip elon-
gates 1t develops interconnected sinuses.
As the ectodermal layers surrounding
each sinus expand, haemocoelic fluid-
pressure maintains the shape of the
structure. During the formative stages
these sinuses are very large (Fig. 7B).
The actively expanding dorsal lip produces
the mantle cavity by folding anteriorly
over the pleural groove. The folding
process resembles Crepidula (Moritz, 1939)
and does not involve an invagination like
that of Pila (Ranjah, 1942). As torsion
and mantle cavity formation proceed,
there is a small invagination on the left
side in the pleural region which forms the
osphradial ganglion (Fig. 5 F). During
the folding process, this ganglion is
shifted into the roof of the mantle cavity.

Twelve Days.—In agitated sea water at
24°C, the final stage of torsion begins
gradually and is completed before the end
of the 12th day. After torsion, the mantle
is no longer adherant to the protoconch
and at times extends beyond the lip of the
shell. Rapid anterior growth produces
the primary body whorl and rudiments of
an apertural beak. The protoconch 1$
composed of scale-like plates with raised
edges which present a serrated outline
when seen in a side view (Fig. 8D).
Increased pigmentation and the scaly
structure of the protoconch greatly reduce
transparency and make observations of
internal developments difficult.

Cephalic modifications affect the sensory
and feeding apparatus. Growth of the
right tentacle provides a primary sensory
organ. Separation of the preoral and
postoral ciliary bands sharply outlines
the food grooves and indicates the close
proximity of hatching. Pedal modifi-
cations include a marked reduction of
the sinuses, formation of the propodial
anlage and development of a metapodial
sensory node.

In the digestive system, the diameter of
peripheral cells has increased 5 fold due

EMBRYOGENESIS AND ORGANOGENESIS 365

to the rapid assimilation of archenteric
yolk. Concurrently, there is further
evidence of disintegration in the
archenteric region including collapsed and
displaced cells and large intercellular
spaces. The result of this reorganization
is the formation of the lumen of the left
digestive gland and isolation of peripheral
cells in this gland (Fig. 7C). Both the
gastric stomach and the anlage of the
style-sac stomach have well defined,
anterior walls free of yolk granules. The
intestine extends from the right side of the
style-sac stomach to the right median edge
of the mantle skirt (Fig. 7C).

The larval heart and the renopericardial
complex begin to develop during the last
stage of torsion (Figs. 7С & 8D). As in
other prosobranchs, the larval heart is
located in the torsional plane, dorsal
and to the right of the esophagus. It
begins to beat shortly after formation.
The presence of this systemic pump is
usually associated with the appearance
of food grooves and the final expansion of
the velar lobes. The renopericardial
complex is located posterior and to the
left of the mantle cavity. Expansion
of the complex begins at about the same
time as the appearance of the larval heart.
The dorsal, balloon-like part of the
complex is the anlage of the adult kidney.
Both larval kidneys are greatly reduced in
size.

Thirteen Days.—Organogenesis has
reached the final phase of the prehatching
stage in which the basic, functional organs
needed by a planktonic veliger are formed.
The digestive system has a complete food
gathering apparatus which lacks only the
final expansion of the velar lobes. The
mouth and esophageal cilia are functional.
А gastric-shield primordium is present,
but only the anterior walls of the gastric
stomach are free of yolky material.
Deutoplasmic reserves remain in the post-
erior walls of the gastric stomach, the left
digestive gland and as scattered remnants

of the archenteric yolk. Dorsal to the
left digestive gland on the right side of the
gastric stomach, an unmodified, right
digestive gland evaginates. The style-
sac stomach has the short, fused cilia
which are so characteristic of this organ.
Intestinal ciliation is complete’ and
apparently functional.

As indicated by the veliger’s reaction to
its environment, all basic nervous and
sensory units are functional. The cerebral
commissure separates from the ectodermal
layer. In addition to the cerebral nerves
already mentioned, there is a pair of
apical nerves which terminate in the
sensory region (Fig. 9A), and a pair of
statocyst nerves, which terminate in the
cerebral ganglia. A positive phototaxis is
indicative of functional optic vesicles.
The major ganglia are arranged in a
typical streptoneurous pattern of cerebrals,
pleurals, pedals, esophageals and viscerals.
A large, prominent osphradial ganglion 15
situated on the left side of the mantle
cavity (Fig. 10A). In the living veliger,
the supra-esophageal osphradial connec-
tive is conspicuous.

The columellar muscle is the major
body retractor. From its origin on the
left side, this muscle passes ventral to the
esophagus and divides into 2 major
branches (Fig. 9B). Each branch divides
again with segments entering the cephalic,
velar and pedal sinuses. Velar insertion is
on both faces of the lobes while pedal
insertion is directly on the operculum and
the ventral ectoderm (Figs. 10A-10B).

Externally, the veliger is modified by
reduction of the apical sensory region and
lateral expansion of the foot. Pedal
expansion accompanies the formation of
large, vacuolated border cells, which give
the ventral pedal region a reticulated
appearance (Fig. 9C). The operculum
extends well beyond the metapodium.
Development of the hypobranchial
gland matches the expansion of the mantle
cavity (Fig. 7D). x

366

CHARLES N. D’ASARO

FIG. 9. Development of Bursa corrugata: A, dorsal view of a veliger 24 hours prior to hatching
(13 days); B, ventral view of a veliger during hatching (14 days); C, ventral view of a 15 day veliger.

Fourteen Days.—Hatching through a
split at the capsular apex begins during the
early part of the 14th day. The point of
release occurs at a definite stage in onto-
geny when the organs necessary for
planktonic existence are fully formed, All

basic organs in the digestive system are
functional and feeding begins almost
immediately. The velar food grooves are
typically wide. А prominent gastric
shield is present in the gastric stomach.
Consolidation of the paired digestive

EMBRYOGENESIS AND ORGANOGENESIS 367

Idg

FIG. 10. Development of Bursa corrugata: A, oblique section through the osphradial ganglion (13 days);
В, parasagittal section through the columellar muscle (13 days); С, frontal section through the style-sac
stomach and the right digestive gland (14 days); D, beginning of diverticulation in the digestive gland

(17 days).

glands is nearly complete. The lumen of
the left digestive gland is unobstructed by
yolk, and there is a drastic reduction in
the number and size of the peripheral
storage-cells. Small digestive ducts
appear in the right digestive gland. The
style-sac stomach contains both major

and- minor typhlosoles bordering an

intestinal groove which leads across the
floor of the stomach into the intestine.
At this stage, both typhlosoles are approx-
imately equal in size.

The protoconch is now composed
primarily of the plate-like structures
mentioned earlier. The plates are
circular and adjacent in regions produced

368 m CHAREES М. D'ASARO

by the primary shell gland. On the body
whorl, which was formed by the mantle,
each plate is overlapped by the preceeding
one. Continued shell growth produces
the columella and deepens the mantle
cavity. The apertural lip has only the
slightest trace of a beak.

Sensory structures are greatly expanded
at hatching. The right tentacle and the
metapodial sensory node are covered with
stiff bristles, contain nervous tissue and are
elongated. Both optic vesicles are
partially closed over the crystalline lenses.

Fifteen Days.—A variety of foods are
found in the stomach of the early plank-
totrophic veliger of Bursa corrugata includ-
ing Platymonas, Dunaliella and assorted
unidentified flagellates. The walls of the
gastric stomach contain black pigment
granules which appear at the onset of
feeding. A second structure associated
with the onset of feeding is the protostyle
(Figs. 9C & 10C). Peripheral storage cells
are no longer present, consequently there
is a reduction in the diameter of the left
digestive gland and the formation of
luminal fissures (Fig. 10D). The inser-
tions of both digestive glands function as
valves controlling the passage of food
particles.

Thirty-six hours after hatching the
veliger develops purplish-black pigment
granules on the propodial rudiment (Fig.
9C). The last vestiges of the larval
kidneys are absorbed. Expansion of the
renopericardial anlage produces а
functional adult kidney and a rudimentary
heart. The latter is located near the left.
ventral side of the kidney to which it is
connected by a renopericardial duct.

Eighteen Days.—The veligers examined
from this and succeeding stages had
atrophied digestive glands with no
diverticulation, a sign of starvation.
Even with selected phytoplankton from
the partially filtered water, growth was
greatly reduced and the daily mortality
was high. The probable cause of

mortality was the lack of a specific food
organism.

Even though the veligers are in a
weakened and morphologically atypical
stage, 1t is possible to make a few assum-
ptions based on present developmental
trends which will give a picture of the next
veliger stage. The protoconch is com-
pletely covered by the previously mentioned
plates and the beak is reduced. Three
types of pigment are present. The shell
is reddish-brown, obscuring the viscera.
Purplish-black pigment granules are spread
through parts of the digestive tract, the
ciliary bands and portions of the foot.
On the foot, a border of large vacuolated
cells with a greenish tint is present (Fig.
9C). А velar lengthening process is
indicative of the future appearance of 2
pairs of velar lobes.

ГУ. DISTORSIO CLATHRATA

1. Breeding Habits, Spawning and Egg
Capsule Morphology

Egg masses were produced in the
laboratory by individuals collected in the
Florida Straits on 14 September, 1965.
Collections were made with a 10-foot try
net (otter type) from the R/V “ Gerda ”
(Stations: G755-756, 24°49'5’N/80°37’W)
at depths of 22 to 26 fathoms. Specimens
were maintained on board ship in plastic
boxes at ambient temperatures and
transferred to a water table in the shore
based laboratory.

Oviposition began within 24 hours
after collection and continued inter-
mittently for 5 days. Copulation was
not observed. Although a variety of
substrates were available, all egg masses
were deposited on polyethylene refri-
gerator boxes. Communal spawning was
not observed. The egg masses of 3
individuals were selected for examination.

Capsule production in this species is
rapid. Approximately 1,500 were
produced in a period of 24 hours or about

EMBRYOGENESIS AND

one every 2 minutes. Fortunately, the
transparent substrate permitted obser-
vations of the spawning process. Pustu-
late capsules are released from the oviduct
and passed through the mantle cavity to
the right side of the propodium, where
they enter a lateral fold running across the
ventral surface. After passing to the
midline of the foot, each capsule is agitated
slightly, surrounded by mucus and then
held firmly on the substrate for a few
seconds. The pedal gland does not
envelop each egg case. When the animal
is undisturbed the process is continuous
with a capsule being held on the right of
the fold as the preceeding one is attached
to the substrate. Spawning females do
not deposit all available ova in a single
mass. This accounts for the wide range in
the total number of capsules per mass
(250 to 1,500).

The position of each capsule clearly
shows the movements of the female during
oviposition (Fig. ПА). As each pustulate
structure is cemented to the substrate,
the propodium moves in a short, lateral
arc. When the Ist arc is completed, the
animal moves over the freshly deposited
material and begins an arc in the opposite
direction.

Like so many other prosobranchs,
the egg capsules of Distoriso clathrata
undergo a series of color changes related
to the acqusition of embryonic pigment.
Initially, the capsules are white or grayish-
white. After ingestion of albumen on the
Sth day, the capsules appear granular.
On the 12th day, a pinkish-brown tint
appears. Gradually this color changes to
heliotrope at hatching on the 15 day.
Capsules with dead embryos remain
white.

Capsular size is relatively uniform
within the main body of the egg mass.
Variations occur at the beginning and end
of oviposition or wherever the spawning
animal made a sharp change in direction.
The average diameter of 10 capsules from

ORGANOGENESIS 369

e 26 EN DR

Pe RAR PE
a es
A sé ae 2 ”

БИ COTE
Saal

FIG. 11. Egg capsules of Distorsio clathrata:
A, segment of a typical egg mass (dorsal view);
B, 3 egg capsules showing the escape-aperture
(dorsal view); С, а cross-section of 2 egg
capsules.

the median portion of a mass was I'l
mm. The average height of the same
capsules was 0°5 mm.

The upper surface of each pustulate
structure is covered by a coriaceous layer
sculptured by curved striations, while an
inner membranous layer forms most of the
walls (Figs. 11B-11C) A basement
membrane attaches the capsules to each
other and to the substrate. At hatching,
a large oval escape-aperture appears on
one side (Fig. 11B).

The number of embryos contained in
each capsule ranged from 20 to 40 with
an average of 35. Since the total number
of capsules per mass varied from 250 to

370 CHARLES N. D’ASARO

FIG. 12. Development of Distorsio clathrata: A, cross-section of the stereogastrula; В, cross-setion
through the stomodeal region; C, frontal section through the esophagus; D, parasagittal section through
the archenteron (5 days); E, oblique section through the stomodeum and the peripheral storage-cell

(S days).

1,500, the material examined contained
from 9,000 to 53,000 embryos.

2. Embryogenesis

The data on early cleavage are incomp-
lete because Distorsio clathrata is rarely
observed spawning, and only a single

series was available for examination. A
second difficulty is introduced by the
presence of a granular, albuminous fluid
in each capsule which obstructs obser-
vation. Removal of the embryos from
the capsules results in a high percentage of
atypical development, SÈ

EMBRYOGENESIS AND ORGANOGENESIS 371

Cleavage proceeds to the 4 cell stage т
8 hours. The formation of primary
blastomeres is highly irregular. Like
most of the higher prosobranchs studied
by Bobretzky (1877) and Pelseneer (1911)
the CD and D blastomeres are consistently
larger. This disparity in size can be
followed in the successors of D though
the later stages of gastrulation. Typically.
D protrudes laterally and ventrally from
the vegetal region. Aftre 24 hours, a
stereoblastula appears.

Epibolic gastrulation begins at 30 hours.
Expansion of the successors of 2d produces
the initial stages of flexion as early as 35
hours. Ectomeres surround the embryo
by the end of the 3rd day. The 2nd phase
of gastrulation forms an open blastopore
and archenteron by invagination (Fig.
12A). Shortly thereafter, the blastopore
partially closes. Deutoplasmic storage,
for the most part, is in the successors of
the macromeres, which are incorporated
into the walls of the archenteron. Two
large ectodermal cells, lateral to the
stomodeum, are the anlagen of the larval
kidneys. Generation of entomesoderm
begins during this stage.

Four Days.—Partial closure of the
blastopore results in the formation of the
stomodeum (Fig. 12B). The cells making
up the stomodeal lip and esophagus
increase in diameter and become ciliated.
No organized ciliation is present in the
archenteron. Rapid, early completion of
the anterior digestive tract is the prelude
to ingestion of the granular albumen
(Fig. 12C). All traces of albumen are
removed from the capsules before the 5th
day. Expansion of the larval kidneys
coincides with the intake of albumen.
These kidneys are located dorsal and
lateral to the stomodeum and extend
sharply away from the ectoderm. Each
renal cell is surrounded basally by
support cells and is in contact with the
rudimentary blastocoel and the entoderm
(Fig. 12C). The kidneys are filled with a

granular fluid and contain colorless
vacuoles (Fig. 12D). A shell gland anlage
develops posterior to the larval kidneys.
Cilia are concentrated on the lips of the
anlage and on the lateral trochoblasts.
Growth of the apical sensory region
begins near the end of the 4th day.

Five Days.—The most obvious change
during the Sth and 6th days is the far
reaching growth process which slowly
shifts the position of major structures.
Part of this flexional process is due to
expansion of the shell gland. During
the Sth day, the embryo is somewhat
spherical with protruding, dorsal larval
kidneys (Fig. 13A). The shifting process
moves the kidneys away from the stomo-
deum (Fig. 13B). At the same time
there is a lengthening of the whole em-
bryo along an axis from the apical sensory
region through the site of the shell gland.
A period of rapid, aimless rotation ensues
with propulsion being provided by the
cilia of the secondary trochoblasts,
stomodeum and sensory region.

Six Days. —The removal of albumen
from the archenteron is due to the activity
of specialized, peripheral storage-cells
(Fig. 12E). These cells, which are almost
entirely vacuolated, become arranged into
a 1 cell thick layer in parts of the anterior
digestive anlage. Cellular intake of
nutritional fluid is probably by phagocytic
activity. The process is aided by the
early appearance of 2 types of cilia, the
slender gastric type and the fused cilia
of the rudimentary style-sac stomach.
Rotation of the stomach contents
moves albumen into the vicinity of the
peripheral cells. Removal of albumen
from the primitive stomach gradually
produces a centrally located transparent
region in the living veliger (Fig. 13В).
Expansion of the pedal anlage adds
another set of growth vectors which
modify the earlier reorganization (Fig.
13С). Vacuoles take up most of the
volume of the larval kidneys.

372 CHARLES N. D’ASARO

FIG. 14. Development of Distorsio clathrata: A, ventral view during expansion of the velar sinuses
(8 days); B, formation of the dorsal process of the shell gland (8 days); C, formation of ganglia on the right
side (9 days); D, localization of peripheral cells in the left digestive gland during the torsional pause seen
in dorsal view (9 days); E, beginning of the last stage of torsion seen in ventral view (10 days).

EMBRYOGENESIS AND ORGANOGENESIS 373

FIG. 13. Development of Distorsio clathrata: A, ventral view during ingestion of albumen (5 days);
B, flexion (6 days); C, peripheral cells and the pedal anlage seen from the right side (6 days): D, evagi-
nation of the shell gland (7 days); E, formation of the sinuses and protoconch in ventral view (7 days).

Seven Days.—Evagination of the shell (Fig. 13D). The major growth vector
gland is followed by the immediate of the shell gland is dorsally oriented.

secretion of a conchiolinous protoconch Both the dorsal and ventral lips of the

374 CHARLES N. D’ASARO

gland contain medial, ciliary bands which
expand laterally. As the shell gland
becomes cap-shaped, the growing edge
contributes to a process which shifts the
larval kidneys anteriorly.

A marked increase in size and the
production of definitive velar ciliation
indicate the beginning of the major stage
of prototrochal developmert (Figs. 13D-
13E). Definitive ciliation stops the
aimless rotation and produces a forward
movement. The apical sensory region
develops the short, fused cilia typical of
this structure. A prominent cephalic
sinus 1$ present.

Eight Days.—Pretrochally, velar expan-
sion begins (Fig. 14A). Growth of the
lobes constricts the wide apical region
and shifts the plate to its definitive
position. The cephalic plates are covered
with delicate cilia unlike the sensory type.
Posterior to the sensory area, the dorsal
ectoderm is marked by large, irregular
epidermal cells.

Posttrochally, the shifting larval kidneys
reach their definitive position in the
pleural region (Fig. 14А). The shell gland
has a dorsal process (Fig. 14B). Pedal
expansion begins, but no sinus is present.
The majority of the peripheral storage-
cells lie in the pleural and pedal regions
(Fig. 12E). An obscure proctodeal in-
vagination appears posterior to the
rudimentary foot (Fig. 15A).

3. Organogenesis

Nine Days.—After the dorsal process
of the shell gland is fully expanded, the
first stage of torsion begins. The primary
effector of this stage is probably the right
larval retractor; however, the origins and
insertions of this muscle could not be
accurately traced. After approximately
90 degrees of rotation occurs, there is a
24 to 36 hour pause.

Three pairs of major ganglia are
formed from the ectoderm during early
torsion (Fig. 14C). The cerebral ganglia

arise aS invaginations at the edges of the
cephalic plates. Small, lateral proli-
ferations into the ventral sinus produce
the pedal ganglia. Dorsal to these
proliferations, lateral invaginations form
the statocysts. In the pleural groove, a
delaminatory process close to the larval
kidneys produces the pleural ganglia.
Development of commissures occurs
almost immediately between the compo-
nents of the cerebral and pleural pairs.
In both cases, the connecting structure
arises as a delaminated, ectodermal band
penetrated by fibrillar outgrowths. All
connectives appear as fibrillar outgrowths
interspersed with ectodermal cells.

Prior to torsion, there is considerable
evidence of utilization of albumen and
degeneration of the remaining macro-

meres. Fragments of yolk are scattered
through the archenteron (Figs. 15A-
15В). The expanding cephalopedal

complex begins to separate itself from the
food-storage regions of the digestive
anlage. This trend in growth ultimately
shifts the remaining peripheral storage-
cells posteriorly in the visceral region. In
addition, new storage-cells appear in the
anlage of the left digestive gland, which
absorb remnants of yolk from the macro-
meres (Fig. 14D). The gastric region,
surrounding the esophageal insertion.
contains non-yolky cells. Аз torsion
progresses, the stomach complex divides
into gastric and style sac components
which are contractile and contain
specialized cilia. The intestine is formed
when the proctodeum opens оп the
anterior face of the style sac.

At this point, the larval kidneys reach
the stage of maximum expansion. Each
kidney is typically spherical, contains a
central vacuole and borders on the
posterior velar sinus (Fig. 15C). On
the right side, mesodermal elements
consolidate into the renopericardial anlage.

Pretrochally, the cephalic and velar
sinuses are well defined. Ciliary con-

EMBRYOGENESIS AND ORGANOGENESIS 375

FIG. 15. Development of Distorsio clathrata: A, parasagittal section through the proctodeal plate
(8 days); В, parasagittal section through the digestive anlage (8 days); С, oblique section through ап
optic vesicle (10 days); D, sagittal section through the digestive anlage and pallial lobe (11 days); E, para-
sagittal section through the left digestive gland (12 days).

nections from the velar lobes to the membranous protoconch covers one third
stomodeum are complete, but the proto- of the visceral mass (Figs. 14C-14D).
troch is unmodified. Posttrochally, the Mesodermal cells consolidate on the left

376 CHARLES N. D’ASARO

side near the protoconch in what was the
pretorsional dorsal process. This band
of cells is the anlage of the columellar
muscle. Except for the opercular gland,
the pedal region is covered with unspecia-
lized cilia.

Ten Days.—Most of this period is
taken up by the torsional pause and a
decrease in length due to consolidation in
each system. A prominent columellar
muscle appears prior to the last stage of
torsion. Branches of the muscle insert
on the walls of the velar and pedal sinuses.
The early protoconch covers ? of the
visceral mass (Fig. 14Е). Secretion of the
operculum is complete.

The left digestive gland arises from the
posterior remnant of the digestive anlage.
The remaining peripheral storage-cells
are isolated in this area. At first, the
lumen of the gland is narrow, but rapid
growth causes expansion as the contents
of the peripheral cells are utilized. Cilia-
tion of the digestive tract is entire.

Developments in the nervous system
are basically consolidations, including
shortening of connectives with а con-
comitant decrease in total length and
compaction of the ganglionic cells into
ovate structures. Optic vesicles invagi-
nate at the border of the apical and
cephalic plates, slightly dorsal to the
cerebral ganglia (Fig. 15C). Each vesicle
is connected to the cerebral ganglia by
outward expanding nerve fibres. Stato-
liths appear in the statocysts.

Eleven Days.—Torsion is completed
during the early part of the 1lth day.
The end of rotation coincides with
completion of the initial protoconch and
formation of the elevated pallial lobe
and early mantle cavity (Fig. 15D). When
the unsculptured and unpigmented
protoconch is in its definitive position, the
dorsal mantle lip begins a process of
ascension similar to that found in Crepi-
dula adunca (Moritz, 1939) and Bursa
corrugata. The lateral fold created by

growth of the shell gland over the pleural
region produces the mantle cavity, but
the folding process is not completed.
Instead. the lip continues to expand
dorsally forming a pallial lobe (Fig. 16A).
Dorsal expansion is followed by the
appearance of atypically long cilia on the
lobe and а heliotrope pigment in the
ectodermal cells of the cavity. At first,
most of the pigment is centralized in the
mantle skirt. Later, it gradually spreads
over the whole cavity.

All major ganglia, except the buccals
and viscerals have developed. The cereb-
ral commissure separates its ganglia with
a nodal expansion that later disappears.
No obvious nerves connecting the cerebrals
to the apical sensory region are present.
Red, retinal pigment is produced in the
optic vesicles. Secretion of a crystalline
lens begins after pigment formation.
The esophageal ganglia are not distin-
guishable until torsion is complete. The
supraesophageal-osphradial connective be-
comes prominent and obscures part of
the visceral loop.

Twelve Days.—The continued dorsal
expansion of the pallial lobe has a con-
comitant effect on the shape of the
protoconch. Since the trend of growth in
the mantle lip is toward the right side, the
aperture lip is distorted in the same
direction (Fig. 16B). There is a slight
disparity in size between the velar lobes
with the right lobe being larger. For-
mation of the right tentacle begins at this
time. A connective extends from the
tentacle to the right cerebral ganglion.
There is no sensory structure associated
with the pedal region prior to hatching.
The ciliated margin of the foot extends to
the lip of the round operculum.

Circulation of fluids. which had been
controlled by sinusoidal contraction, now
becomes systematized. The renoperi-
cardial anlage, located on the dorsal left
side near the mantle cavity, has a schizo-
coel. This structure will become the

EMBRYOGENESIS AND ORGANOGENESIS 377

FIG. 16. Development of Distorsio clathrata: A, formation of the pallial lobe in velar view (11 days);
B, formation of the pallial lobe (12 days); C, dorsal view of the visceral region only (13 days); D, dorsal
view of the visceral region and the foot (14 days).

adult kidney after evaginations produce
the adult heart and possibly the gonadal
anlagen. Interconnecting sinuses on the
floor of the mantle cavity in the torsional
plane produce rudiments of the larval

<
À

heart and the anterior aorta. The larval
kidneys are reduced to a quarter of their
original size.

Thirteen Days.—Numerous myoblasts
are connected to the dorsal mantle lip

378 CHARLES М. D'ASARO

where they function as pallial retractors.
Other large clusters of similar cells occur
just posterior to the renopericardial anlage
where they act as accessory visceral
retractors. Myoblasts unrelated to those
of the columellar muscle form radial pedal
retractors and connect the ectodermal
layers of the foot. The major retractor
or columellar muscle has its origin on the
left side of the protoconch and passes
anteriorly through a fold in the visceral
mass (Figs. 15Е & 16C). After passing
ventral to the esophagus the insertions
are in the cephalic and pedal regions.

Final absorption of the larval kidneys
takes place over a 24-hour period.
Remnants of the kidneys are reduced to a
cluster of granular, yeHowish cells. No
excretory bodies were observed being
released.

The anlage of the definitive right
digestive gland is the last of the major
digestive organs to develop. It appears
just dorsal to the junction of the left
gland and the gastric stomach. Yolk
filled cells still give the complex stomach
a rounded appearance (Fig. 16C).

Externally, the veliger is only slightly
modified. Pedal ciliation is complete.
On the metapodium there is а sensory
node with bristles projecting beyond the
edge of the operculum. The pallial lobe
is carried folded over the dorsal aperture-
lip.

Fourteen Days.—Hatching through an
oval escape-aperture (Fig. 11B) begins at
the end of the 14th day. Apparently
enzymes secreted by the embryo dissolve
the borders of the aperture plug as
suggested by Pelseneer (1935) and
Davis (1967). Constant incidental colli-
sions by the rapidly swimming veligers
gradually tear away the oval region. Once
the capsule is open, all normal veligers
escape within minutes. Hatching 15
uneven and does not always begin with the
oldest capsules. It is important to note
that at the moment of escape each veliger,

regardless of age, has reached the same
ontogenetic stage.

All major ganglia and sensory organs
required by a planktotrophic veliger are
present. The visceral ganglia, which are
difficult to idertify. appear as simple
proliferations on the floor of the mantle
cavity. The left tentacular anlage is
nodular and undeveloped, but it has a
nerve trunk from the left cerebral ganglion.
A similar nerve extends to a ganglion at
the distal end of the right tentacle.
Sensory organs cover the right tentacle.
In the left posterior mantle cavity, а
swelling marks the initial development of
the osphradium.

Including the food grooves, the veliger
has a completely functional digestive
system. Feeding begins immediately after
hatching. The walls ot the style-sac stomach
contain yolk-free cells (Fig. 16D), although
some remnants of embryonic food
are localized in the gastric food-storage
region. An evagination into the anlage
of the right digestive gland occurs before
it becomes functional. At this stage. the
intestine extends directly from the anterior
style-sac stomach to the right side of the
mantle skirt (Fig. 17А). The heliotrope
pigment, which was first localized in the
mantle cavity. spreads to the esophagus,
gastric stomach, renopericardial anlage,
larval heart and the anterior aorta.

Both hearts are active at 14 days.
Contraction by the larval heart is much
more rapid than that of the definitive
heart which rarely contracts. The adult
structure is located ventral and to the
left of the definitive kidney (Fig. 16D).
А renopericardial duct connects these
organs. Anlagen of the ductus arteriosus
and posterior aorta are present as narrow
sinuses. Except for the anterior aorta,
the functional circulation is maintained
through interconnecting sinuses. A renal
valve opening into the mantle cavity could
not be detected, but the kidney contracts
rapidly.

EMBRYOGENESIS AND ORGANOGENESIS 379

msl

FIG. 17. Development of Distorsio clathrata: A, dorsal view of the visceral region only (14 days); B,
right side of a carinate veliger (15 days); C, velar view of a carinate veliger (16 days); D, right side of the

visceral mass only (16 days).

Conspicuous lines of cells appear in the
mantle skirt and on the edge of the foot
(Figs. 16D & 17A). These pallial cells
are associated with formation of a carina

on the protoconch at a later stage. They
are organized into a band, two cells wide,
which extends from the posterior mantle
cavity near the osphradium to the dorsal

380 CHARLES N. D'ASARO

edge of the pallial lobe. Each cell appears
to have a secretory nature and is closely
associated with the pallial ectoderm in
contact with the protoconch. Оп the
foot, large vacuolated cells develop on the
mesopodial and metapodial border (Fig.
16D) and gradually spread into the ventral
ectoderm.

Fifteen Days.—The appearance of a
complex carinate structure attached to the
dorsal aperture-lip spectacularly marks the
first day of planktotrophic growth (Figs.
17B-17C). Production of the conchioli-
nous keel by the раша! lobe begins shortly
after hatching. The lobe is extended
posteriorly over the protoconch and
executes an anteriorly directed arc as
secretion progresses. After the initial
arc, all further carinal growth proceeds
corcomitant with the formation of the
protoconch. The carina 15 attached only
on the apertural beak at the beginning of
the arc: however, further growth lengthens
the point of attachment. Seen laterally.
there are numerous growth lines parallel
to the «dorsal. lobe (Fig. 178). Ber-
pendicular to the lobe there are 8-11
bands of conchiolin. When seen in
cross section it is immediately apparent
that the bands of conchiolin actually
delimit chambers (Fig. ISA). The third
chamber from the top is usually the
largest with the sides tapering rapidly to a
sharp. dorsal edge. A more gradual
tapering occurs between the third chamber
and the basal attachment. Occasionally,
a pause in the secretory process produces
a break in the bands (Fig. 17B). The
height of the carina averages 177# with
the longest dimension of the veliger
including the carina averaging 460».
Clench & Turner (1957) examined the
protoconch on the adult shells of Distorsio
clathrata but they found no sculpture
of any type. Apparently the carina is a
characteristic of the early larval stages
that is covered over by later whorls or
lost. Concurrent with keel production,

a light brown pigment is evenly distributed
through the protoconch and the oper-
culum becomes reticulated. A rudi-
mentary columella 15 present.

Modifications in the digestive system
are concerned with feeding and handling
increasing quantities of alga! food. АП
embryonic food stored in the walls of the
complex stomach has been used. Rem-
nants of the peripheral storage-cells are
still present in the left digestive gland.
The typhlosoles of the style-sac stomach
produce a protostyle when feeding begins
(Figs. 18B-18D). Heliotrope pigment is
distributed through the whole digestive
system except for the digestive glands.
Sites of greater concentration are located
in the walls of the style-sac where the
pigmented cells are arranged in a linear
pattern. The intestine bends sharply to
the right, just posterior to the kidney, and
extends to the right side of the mantle
cavity. Then it curves dorsally to the mid-
dle of the cavity and turns ventrally again
near the edge of the mantle (Fig. 18Е).
Occasionally, the swollen and ciliated anal
region extends beyond the pallial lip.

Sixteen Days.—Further expansion of
the carina is balanced by dorso-ventral
elongation of the velum, which, with
lateral folding, gradually produces 2 pairs
of velar lobes (Fig. 17C). When fully
expanded the narrow dorsal lobes extend
to the upper edge of the carina. Nor-
maliv, they are held at a 45 degree angle
to the keel: The ventral lobeszrare
shorter and wider than the dorsal pair.
All velar food grooves are narrow.

А rudimentary hypobranchial gland
occupies the mantle skirt between the
intestine and the pallial lobe. The parallel
rows of cells in the lobe extend posteriorly
to a large pallial sinus which separates
them from the edge of the definitive kidney
(Fig. 18F).

Transparent cells of undetermired
furction are scattered over the esophagus
and intestine (Fig. 170). Insertions of

EMBRYOGENESIS

AND ORGANOGENESIS 381

FIG. 18. Development of Distorsio clathrata: A, cross-section of the carina (15 days); В, cross-section
of the body at hatching (15 days); C, oblique section through the stomach (15 days); D, cross-section
through the body (16 days); E, parasagittal section on the right side (18 days); F, parasagittal section

through the kidney (18 days).

ducts in the gastric stomach are easy to
identify at this stage. The esophagus
opens on the right ventral side at the
edge of the style sac. Of the digestive
ducts, the left one is the largest and opens
‘on the posterior left side (Fig. 18C). A

portion of the left gland extends from its
point of insertion under the stomach to a
definitive position in contact with the
right gland. The right digestive duct
opens dorsal to the esophageal insertion.
Allinsertions function as valves, There is

uy
co
nN

no caecal region in the gastric stomach.

Three contractile organs are present,
the larval and adult hearts and the adult
kidney. A large renal duct, which res-
ponds to each contraction, opens into the
posterior mantle cavity (Fig. 17D).
Pallial sinuses already are arranged in a
ctenidial pattern.

Eighteen Days.—Pedal modifications
begin with the formation of the propodial
anlage and the metapodial node. A
terminal metapodial lobe is found in
most planktotrophic veligers, but the
medial node is uncommon (Fig. 17В).
Large, transparent cells, similar to the
border cells, lie in parallel lines in the
mid-vental foot. The reticulated oper-
culum is approximately circular. Within
the foot, the nerve pattern is modified
by a folding of the pedal commissure and
the formation of a metapodial nerve and
ganglion (Fig. 17B). Four distinct
branches of the columella muscle insert
in the foot.

The mouth becomes triangular in shape
and mobile concomitant with the
appearance of the propodial anlage.
Purplish-black pigment outlines tne mouth
and typhlosoles. Both digestive glands
are elongated with the left being twisted.
Prominent granulations develop in the
anterior lobe of the left gland and in the
whole right gland. The first stages of
digestive diverticulation are marked by the
appearance of swollen areas on the left
side of the major gland.

The eighteen-day stage was the last to
be examined in this series because the
gradual decrease in thickness of the
digestive glands without corresponding
growth was indicative of slow starvation
and atypical development.

V. DISCUSSION

1. Taxonomic Characters of the First
Veliger Stages

From hatching to the beginning of

CHARLES N. D’ASARO

digestive diverticulation the veligers of
the species examined have a number of
general characters common to other
prosobranch veligers as well as a number of
more specific characters. Prosobranch
characters include a dextral protoconch
with a single whorl, bilobed velum, right
cephalic tentacle, metapodial sensory
structures and a complex gastric system
including a style-sac stomach. protostyle
and gastric shield. An apertural beak on
the protoconch with some type of linear
sculpturing is characteristic of most long-
term, prosobranch veligers. A prominent
osphradial ganglion and the supra-
esophageal osphradial connective mark
the higher prosobranchs. To prevent
confusion with similar opistobranch
veligers, when coiling of the shell is not
pronounced, the absence of a secondary
kidney located rear the anus should be
noted.

Bursa corrugata has a relatively un-
distinguished first veliger stage. The
typical apertural beak is reduced in size
until it is difficult, on this character alone,
to distinguish between this species and ап
opistobranch such as Coryphella (Hurst
1967). However, the dextral shell and the
lengthening of the velar lobes into 2
pairs are characteristic of planktotrophic
prosobranchs. Characters indicative of
the superfamilial relationships of В.
corrugata can be based with some degree
of certainty on the sculpture of the
protoconch (for the Ist veliger stage only).
The reticulated sculpture formed by fused
plates, which have raised edges, has been
described for tonnids and now bursids,
both of which are in the same superfamily,
Топпасеа. Amio (1963) listed the types
of protoconch sculpture found in a
number of families and he included the
tonnids along with the cypraeids,
cerithiids and littorinids in a group with
so-called ‘“ beaten ” shells. Thorson
(1940) also used the terms “* beaten ” in
his description of the veligers of Dolium

EMBRYOGENESIS AND ORGANOGENESIS 383

(=Tonna). Examination of the literature
and fresh material from the groups in
Amio’s category has shown that 2 or more
structural types are included. The
** beaten ” or reticulated type formed by
fused plates is more typical of tonnids and
bursids while the other groups have a
sculptured network without plates.
The Ist veliger stage of Distorsio
clathrata has the same general prosobranch
characters as Bursa corrugata with one
exception. The velar lobes change rapidly
from one equal pair to 2 unequal pairs
during the first 24 hours after hatching.
The color of the soft parts and the unusual
structure of the protoconch offer characters
of value on a generic level. Usually color is
considered an unimportant character,
but Fretter & Graham (1962) have pointed
out its usefulness in identifying proso-
branch veligers. Although pigment
granules of several types are scattered
through the soft parts of D. clathrata, the
heliotrope pigment, which colors the
organs of the mantle cavity and the whole
digestive system except for the digestive
glands, is distinctive. In the veligers of
other species, black or shades of purple are
common, but typically the pigment is
located in specific glands or ectodermal
chromatophores. The 2nd generic
character is the carinate protoconch.
The complexity of the carina rivals that
of the echinospira group, since the keel is
made up of a number of chambers

attached to the shell. No other
knownveliger has а similar carinate
protoconch.

There is one condition which hinders
the use of the previously mentioned
characters in identification. Long-term
plankototrophic veligers do not have
instars in development. The earlv veliger
stage is of relatively short duration,
transcending into another stage in which
both general and specific characters change
in relation to definitive developments.
Because of this gradual change, identifi-

cation is difficult when only part of the
ontogeny is known.

2. Development of Natatorial Indepen-
dence

A study of early organogenesis in the
species examined points out the immediate
problem of the long-term veliger. the
development of natatorial independence.
This ontogenetic process is in contrast
to that occurring in prosobranch groups
with direct development in which the
natatory apparatus is suppressed, or in
groups with short-term veligers in which
there is an early appearance of structures
with great post-metamorphic significance,
such ¡s the radular sac.

The velar apparatus should be examined
first because of its direct relationship to
swimming and feeding. After completion
of torsion, the cells associated with the
rudimentary protoconch separate in to 2
distinct ciliary bands. These remain in
close association until a few hours before
hatching when a shift in position results
from the formation of ciliated food-
grooves. The ciliary apparatus of the
mouth and the median pedal regions 1s
completed at this time. As a result, the
veliger is equipped at hatching for swim-
ming and feeding.

In the digestive system, most modifi-
cations necessary for assimilation are
completed prior to hatching. Embryonic
foods from the gastric storage region and
the remaining storage cells of the left
digestive gland provide reserve energy to
sustain the early veligers in their first
planktotrophic stage. In atypical situ-
ations, the food reserves can maintain
Bursa corrugata 9 to 10 days and Distorsio
clathrata up to 14 days. If laboratory
culture is successful the embryonic foods
are used much faster. In Thais haemas-
toma, when reserves are coupled with an
acceptable algal food. most stored food is
absorbed in 4 or 5 days (D’Asaro, 1966).
Fluctuations in the external food supply

384 CHARLES N. D’ASARO

modify the absorption rate in all storage
areas. With an increase in acceptable
phytoplankton, there is an increase in
growth and rapid decrease ir stored
nutrients. This is indicative of a
mechanism to delay growth when external
food supplies are minimal. Larval
structures associated with the utilization
of phytoplankton, which are lost or modi-
fied after metamorphosis, include the
style-sac stomach, protostyle and gastric
shield.

All major ganglia except those
concerned with the buccal apparatus are
differentiated prior to hatching. Of these,
in Bursa corrugata and Distorsio clathrata,
the cerebrals and pedals are larger, while
in certain advanced groups, for example
Thais haemastoma (D’Asaro, 1966), the
osphradial ganglion is most prominent.
At hatching, each species exhibits a
positive phototaxis which is indicative of
functional photoreceptors, while responses
such as contraction upon stimulation
Suggest the development of functional
tactile organs.

The transition from an embryonic stage
to a free-living stage is most obvious in the
excretory systems. As the larval kidneys
cease functioning and are absorbed
concurrent development of the renal
anlage produces a functional excretory
organ. Only Bursa corrugata retains the
larval kidneys for the first 2 or 3 days of the
free-living stage.

Expansion of the velar lobes and other
sinusoid regions is influenced by fluid
pressure which is maintained by the larval
heart. This commences before the final
development of the first pair of velar lobes.
At hatching, the larval heart is contracting
rhythmically. The definitive heart
becomes functional at or slightly after
hatching and slowly takes over the
functions of the larval pump.

Hatching in each case occurs when the
combined development of all organ
systems has reached a point at which the

planktotrophic veliger can make use of
the primary food supply in the ocean.
As mentioned earlier, opening of the egg
capsules is probably the result of enzy-
matic action controlled by the embryo. If
veligers are released artificially from their
capsules before reaching this stage, morta-
lity during rearing is abnormally high.

3. Ontogenetic Variations and Their

Significance.

Variations in the general ontogenetic
pattern in prosobranchs, which are some-
times quite marked even in members of the
same genus, can be placed in several
categories: those which аге significant
in the organization of the embryo, those

An example of organizational variation
between the species examined concerns
the presence of polar lobes in Bursa
corrugata and the absence of lobes in
Distorsio clathrata. These polar struc-
tures are also found in certain poly-
chaetes, scaphopods, pelecypods and
other prosobranchs. In several tonna-
ceans which have been examined to date,
at least two different patterns of lobe
movement can be mentioned. A good
example of a rhythmic type of polar lobe
movement is found in B. corrugata. In
this case, a plasmic shift, expanding and
retracting a lobe containing granular,
nonyolky protoplasm, takes place at
each maturation and cleavage stage
through the second cleavage. Argobuc-
cinum oregonese (Phillpott, 1925) has a
nonrhythmic, granular lobe present up to
the second cleavage. Anderson (1959)
looked at the early cleavage stages of
Cymatilesta spengleri, but no mention
of polar lobes was made.

The Neogastropoda typically have lobe
formation. In the Muricacea, Purpura
lapillus (Pelseneer, 1911), Ocenebra
aciculata (Franc, 1940) and Thais
haemastoma (D’Asaro, 1966) all have
polar lobes, but differ from the tonnaceans
in having nonrhythmic, deutoplasmic

EMBRYOGENESIS AND ORGANOGENESIS 385

types. In the Buccinacea, a rhythmic
pattern similar to that in Bursa corrugata
appears again. //yanassa (Morgan, 1935)
has a rapid sequence of production with
a yolky lobe extruded at each stage. Not
all buccinaceans have a rhythmic pattern.
Fulgur (Conklin, 1907) has по lobe
formation up to the first cleavage, when
a granular, non-deutoplasmic lobe
appears.

Several points can be made from the
examples. First, except for some mem-
bers of the same genus, there is no case in
which the sequence, quantity and quality
of the polar lobes exactly matches that of
another group. Second and more
important, in groups where the greatest
similarities occur, such as the bursids and
the nassariids, the homologies are
exceptions to the typical type of develop-
ment in that family. The function of the
polar lobe in embryonic organization was
partially explained by Clement (1952);
consequently, it is probable that the
extreme variation in size. content and
sequence of formation reflect the solution
of organizational problems at the embryo-
nic level. As noted by DeBeer (1958),
polar lobes may not have been possessed
by a common ancestor, but instead the
prerequisite conditions for their develop-
ment have been inherited. Therefore,
although lobe formation is an obvious
point in ontogeny it offers no reliable clues
for phylogeny within the Prosobranchia.

Perhaps the best example of divergence
between the 2 species in a major onto-
gerrtic process which affects the larval
stages, can be found in the early develop-
ment of the digestive system. In Bursa
corrugata, the archenteric wall arises from
the digestion of the large yolky blasto-
meres. There is no evidence of albumen
ingestion; instead, the macromeres
disintegrate and are absorbed or
phagocytized by peripheral storage-cells,
producing an open archenteron. Distor-
sio clathrata also has peripberal storage-

cells but the process is different. In this
case, the archenteron is open at the end of
gastrulation, since it is formed partially
by invagination. As soon as the blasto-
pore (stomodeum) becomes ciliated, the
viscous albumen is ingested, filling the
archenteron. Then the albumen is
phagocytozed by peripheral cells in the
archenteric wall.

Several important points should be
mentioned. First, the processes creating
the archenteric cavities are entirely
different. Second, the major functional
difference between the 2 species with
peripheral cells is that one stores ovarian
yolk in peripheral cells, while the other
stores initially oviducal albumen. Third,
the peripheral storage-cells in D. clathrata
are somewhat different in structure and
are more widely distributed through the
digestive anlage than those of В. corrugata.
Aside from these differences, both species
hatch between the 14th and 15th day and
have a long-term plantotrophic veliger
with a digestive system typical of that
stage. Ontogenetic deviations ш the
Prosobranchia due to the various types
of early larval nutrition were examined
by Fioroni (1966a, 1967) and correctly
termed examples of caeogenesis.

Although an explanation of the torsional
process is not a purpose of this paper, it is
desirable to point out a major difference
between torsion in the Archeogastropoda
and that in the higher prosobranchs, since
the process directly affects larval and adult
stages. Crofts (1955) suggested that
differential growth associated with deve-
lopment and migration of tre columellar
muscle brings about the 2nd stage of
torsion, at least in the Archeogastropoda.
The ontogenetic evidence from the species
examined does not completely support
this claim for the higher groups for the
following reasons. In each species the
organization of columellar myoblasts
begins before the onset of the second stage
of torsion and is completed before or near

386 CHARLES N. D’ASARO

the end of this stage. There isno evidence
of migration by the insertion of the
columellar muscle during torsion; and
finally, there is no columella present until
several days after torsion.

An alternative cause for the 2nd
torsional stage in the higher prosobranchs
can be considered. It could be a complex
of differential growth vectors (which may
include those of the columellar muscle
evolved from the mechanism demonstrated
by Crofts in more primitive groups. Naef
(1913) thought the whole torsional process
in higher prosobranchs was derived from a
secondary modification based on differ-
ential growth. Some evidence exists
to support part of this claim. Fretter &
Graham (1962) listed 5 species in which
torsion 1$ said to be induced only by
differential growth. It can also be stated
that a certain amount of growth must
occurr just to compensate for the shearing
stress which takes place in the affected
tissues. This’ factor | is especially
important in the larger yolky embryos
possessed by many mesogastropods and
nearly all neogastropods.

The final example of divergence between
the species examined concerns the proto-
conch ard appears to be significant at the
larval level. It was stated earlier that the
reticulated sculpture formed by fused
plates is characteristic of most tonnids
and is also found in bursids, both of which
are tonnaceans. Distorsio clathrata,
which was included in the Cymatiidae
by Clench & Turner (1957), is also а
tonnacean; however, the protoconch of
the Istlarval stage is unsculptured except
for growth striae and a dorsal carina. The
carina is reminiscent of the linear for-
mations of dorsal spines or knobs present
in the tonnids examined by Simroth (1911)
or the unidentified veliger of Cymatium
type figured by Lebour (1945), yet its
greater complexity should not be over-
looked. The chambered character of the
keel is a result of the secretion of perios-

tracum (conchiolin) by the pallial lobe.
Unusual larval structures resulting from a
modification of this process are not
unknown. A classical example is the
echinospira larva of the Lamillariidae,
Eratoidae and Capulidae. There is no
question that the echinospira is a larval
adaption of significance only to the larva.
This appears to be true for D. clathrata
also, since Clench & Turner (1957) did not
find a keel on the protoconch of postlarval
shells of this species and showed that the
distorted shell is the result of overgrown
denticles and plicae.

In summation, the following hypotheses
can be made: (1) the early veliger stages
of prosobranchs have specific morpholog-
ical characters wkich may allow grouping
or identification when the larval stages of
all members of a taxa have been studied:
(2) the immediate problem of long-term
planktotrophic veligers is to develop
natatorial independence, in contrast to the
delayed development and modified
digestive systems in species without free-
living larvae: and (3) most of the onto-
genetic variations between the species
examined are of significance only in the
larval stages.

ACKNOWLEDGMENTS

The author is greatly indebted to Dr. H. B. Owre
for her assistance and review of the manuscript.
Helpful comments on the manuscript were also
made by Dr. L. Thomas and Mr. R. A. Smith.
Special thanks are due to Dr. F. M. Bayer,
Dr. H. B. Moore and Dr. B. McPherson for
collecting many of the specimens used in this
study.

LITERATURE CITED

ABBOTT, R. T., 1954, American seashells. Van
Nostrand, New York, N.Y., 541 p.

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EMBRYOGENESIS AND ORGANOGENESIS 387

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388 CHARLES

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D’ASARO

tions in Iran, Part 2. Ejnar Munksgaard,
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Received for Publication 13 Jan. 1968.

Accepted for Publication 25 April 1968.

RESUME

EMBRYOLOGIE COMPAREE DU DEBUT DE L’ORGANOGENESE
DE BURSA CORRUGATA PERRY ЕТ DISTORSIO CLATHRATA
LAMARCK (GASTROPODA: PROSOBRANCHIA)

С. М. D’Asaro

Par suite de la proche parenté de Bursa corrugata et Distorsio clathrata au niveau de
la famille, une étude comparative de leur développement peut mettre en évidence certaines
différences ontogéniques qui indiquent une adaptabilité au niveau larvaire. Dans ce

but, les données suivantes sont présentées.

La reproduction, l’emission des gametes et

la structure des capsules des oeufs sont décrites. L’ embryologie, у compris le premier
stade de torsion, est esquissée. L’organogenése est suivie depuis la pause suivant la
torsion jusqu’a la fin du premier stade veliger planctotrophique, ce qui coincide avec
Papparition de diverticules dans la glande digestive gauche.

En résumé, les caracteres taxonomiques du premier stade veliger sont esquissés et les
changements progressifs des caracteres larvaires sont notés. Les tendances du développe-
ment d’espèces à longue période planctotrophique conduisant à la natation libre sont
discutées, compte tenu de la différenciation des organes. Les variations ontogéniques
qui sont examinées comprennent la formation de lobes polaires, certains aspects de la
torsion, les modes de nutrition des larves et la sculpture de la protoconque.

RESUMEN

EMBRIOGENESIS COMPARADA Y ORGANOGENESIS TEMPRANA
DE BURSA CORRUGATA PERRY Y DISTORTIO CLATHRATA
LAMARCK (GASTROPODA: PROSOBRANCHIA)

С. М. d’Asaro

Por sus estrechas relaciones en el nivel familiar, ип estudio comparado de Bursa cor-
rugata y Distortio clathrata puede demostrar ciertas disimilaridades en ontogenia indi-

cadoras de adaptación en el estado larval.

Con tal próposito se presentan los datos

siguientes sobre puesta y estructura de las cápsulas ovígeras, crianza. Embriogenesis,
incluyendo desarrollo del primer proceso de torsión, se sumariza. La organogénesis
fué seguida desde la pausa torsional hasta el final del estado velígero plactotrófico, el
cual coincide con la diverticulación de la glándula digestiva izquierda.

En resumen, los caracteres taxonómicos del primer estado velígero son delineados,
y se nota el cambio gradual de los caracteres larvales. Se discute la tendencia, en el
desarrollo de las especies con largos periodos planctotróficos, a la independencia natatoria,
en relación al sistema de órganos envueltos. Entre las variaciones ontogénicas
examinadas se incluyen: formación de lóbulos polares, algunos aspectos de la torsión,
métodos de nutrición larval, y escultura de la protoconcha.

EMBRYOGENESIS AND ORGANOGENESIS 389

ABCTPAKT

О СРАВНИТЕЛЬНОМ ЭМБРИОГЕНЕЗЕ РАННЕМ ОРГАНОГЕНЕЗЕ У
BURSA CORRUGATA PERRY И DISTORSIO СГАТНКАТА LAMARCK

(GASTROPODA: PROSOBRANCHIA)
Ч. H. Д?’АЗАРО

При сравнительном изучении развития у близко-родственных (на уровне
семейства) форм Bursa corrugata и Distorsio clathrata, можно заметить некоторое
несходство в их онтогении, что может служить показателем адаптации их
личинок к условиям среды. Для получения этих выводов были прослежены и
описаны их размножение, откладка яиц и структура яйцевой капсулы, а так-
же эмбриогенез, включая развитие зародыша, вплоть до первой стадии тор-
сии. Органогенез был прослежен, начиная от торсионной паузы вплоть до
первой планктонотрофной стадии велигера, которая совпадает с образовани-
ем дивертикулы левой пищеварительной железы.

В итоге определены: таксономический характер первой стадии велигера и
постепенное изменение во времени общего характера личинки. Рассматрива-
ется тенденция в развитии планктонотрофных видов с долго-плавающей ли-
чинкой, приводящая к независимому образу жизни, в связи с системой рас-
положения внутренних органов. Рассматриваются также онтогенетические из-
менения, включая образование полярных лопастей, некоторые вопросы, CBA-
занные с торсией, способы питания личинок и скульптура протокоиха.

ae Fe Ale | a er р
DRM EN bie >) te AN dr

q pare es ем be W И

MALACOLOGIA, 1969, 9(2): 391-401

SURVIVAL OF THE EMBRYOS OF THE
GREY FIELD SLUG AGRIOLIMAX RETICULATUS,
FOLLOWING DESICCATION OF THE EGG

Christopher J. Bayne!

Department of Zoology
University College of North Wales
Bangor, Caenarvonshire, U.K.

ABSTRACT

Embryos of Agriolimax reticulatus were found to survive a weight loss (by dehydration)
of 60—80% from the eggs. Advanced embryos were more tolerant of drying than very
young embryos. Newly laid eggs were less susceptible when drying occurred more
rapidly; i.e., at 50% relative humidity as compared to 90% relative humidity. Drying
appeared to have no delayed effect upon the viability of the embryos.

Eggs of both ages lost weight at the same rate, bu! grouping caused a significant slow-
ing of the rate compared to that of eggs dried singly, the outer eggs of a group drying

more rapidly.

INTRODUCTION

The eggs of the terrestrial slug Agrioli-
тах (Deroceras) reticulatus appear to
have no structural provision for resistance
to desiccation, and studies have shown
that these eggs have a very poor water
retaining capacity (Bayne, 1968). It has
been recorded (Carrick, 1939, 1942;
Arias & Crowell, 1963) that turgidity
of the eggs is dependant upon the main-
tenance of permanent contact with a
moist surface. Since development of the
embryos may take several months in the
surface layers of the soil (Carrick, 1942),
the eggs may from time to time be exposed
to drying conditions (South, 1965), and
there is the possibility that the embryos
might be specifically equipped to survive
such exposures.

This paper reports on experiments
which measured the effect of desiccation
upon the embryos of A. reticulatus.

MATERIALS AND METHODS

Newly laid eggs and eggs with advanced
embryos. (stage! "V,. “Carrick, 1939)
of Agriolimax reticulatus were used.
Newly laid eggs were obtained from slugs
in laboratory culture as described pre-
viously (Bayne, 1966). Stage У (Fig. 1)
is reached after about 2/3 of the develop-
mental period, and is easily determined by
examination of the transparent eggs under
a dissecting microscope. Eggs containing
such advanced embryos were obtained
by keeping newly laid eggs in moist
conditions at 17-20°C for 1-2 weeks.
Each egg was examined prior to the
experiment and those appearing to be
abnormal. unhealthy, dead, infertile, or
in any way damaged, were rejected.

The desiccation apparatus, consisting
of a glass fibre balance in a constant
environment chamber, has been described
previously (Bayne, 1968).

1 Present address: Museum of Zoology, The University of Michigan, Ann Arbor, Michigan 48104,

U.S.A.

392 CHRISTOPHER J. BAYNE

Newly laid egg

SN пение
DN ES
200000 unidentified
= ) y) inclusion
2
Yj

zygote

FIG. 1.
fate of the unidentified inclusion is uncertain, and it may be ingested, together with the perivitelline fluid,
by the embryo. Measurement line 1 mm.

In order to determine the ability of the
embryos to survive drying of the eggs,
groups of 10 eggs were desiccated to
different degrees, and another 5 were
kept as controls for each group. The
amount of desiccation undergone by the
individual eggs of a group varied slightly
due to their position on the pan, the
outermost drying more rapidly. More
critical experiments were, therefore, carried
out using single eggs: in this way the
exact amount of drying undergone by
each egg could be controlled, permitting a
more accurate determination of the ‘upper
lethal limit’. With these latter experi-
ments another 2 eggs were cultured as
controls for each experimental egg.

Prior to each experiment the fully
hydrated eggs were rolled on filter paper
to remove excess water. When groups
of 10 eggs were dried to 90, 80, 70, 60 or
50% of their original weight, the eggs
were spread in a single layer, with neigh-
bouring eggs in contact. For experiments
involving a greater degree of desiccation,
the eggs were spaced out on the pan to
ensure greater uniformity of individual
desiccation rates.

Experiments at 90%, and at 50%, relative
humidity (R.H.) were carried out once
with the fan on and once with it off.

Egg with Stage V embryo

perivitelline
fluid

-embryo

Jelly

Agriolimax reticulatus eggs, newly laid (left) and containing a stage V embryo (right). The

The temperature was kept at 20+0-5°C
At the higher humidity the time taken to
lose a weight of water was 4-5 times
as long as at the lower humidity, so that
exposure of the embryo to reduced
hydration was more prolonged at 90%,
REL:

As soon as the eggs had been dried the
requisite amount, they were transferred
vo the culture vessel (Fig. 2) where they
were kept on saturated filter paper, in
contact with free water. The culture
vessel was kept in the dark in a room at
19+2°C. These conditions have been
shown to be conducive to healthy develop-
ment (Cardot, 1924; Carrick, 1942), and
hatching occurs in 2-3 weeks.

The eggs were examined at weekly
intervals, and the numbers living and
hatched were noted. Newly laid eggs
were considered to have survived desic-
cation (1.e., to be viable) if development
continued after the experiment, and stage
V embryos if the caudal and cephalic
vesicles (Carrick, 1939) were pumping
after rehydration. Hatchability was
assessed simply as the numbers hatching
within 3 or 4 weeks.

The results presented below represent
experimental data weighted by control
values.

SURVIVAL OF AGRIOLIMAX AFTER DRYING 393

b+ tbe +t et
= + + + Een ed + +
+ ee eats. +

bt EE HH ++
HR HE EE HE

filter paper

FIG. 2. The culture chamber to which eggs were transferred directly after desiccation.

A. Plan of

the lid. The numerical order of the culture sites was randomised by use of a table of random numbers.
Eggs from successive experiments were placed on the correspondingly numbered sites. Crosses delineate

culture sites. В. Sectional front elevation.

water.
Viability (\) was calculated as follows:

where vd=percentage viability of desic-
cated eggs.

vc=percentage viability of control eggs.
By this means any decrease in viability
in the controls was used to give a com-
pensatory factor which then increased the
viability value of the experimental eggs.

The hatchability value (H) is the number
hatching expressed as a percentage of those
х 106

me ( hd
surviving, | — —

= » The control
vd

The filter paper was kept saturated with distilled

data were then used to weight this value as

above. Thus:
\ 200—
H=( hd RN ( _ 200- he )
vd / 100
_ hd(200—hc)
vd

where hc and hd are the percentage values
for control and desiccated eggs.

Dry weight determinations were made
of newly laid eggs and of eggs containing
stage V embryos. For each of the 2
age classes 3 separate determinations were
made. Groups of 20 clean eggs were
weighed, then dried to constant weight
in an oven at 107=1*C,

394 CHRISTOPHER J. BAYNE

TABLE 1. Viability and hatchability values for eggs of Agriolimax reticulatus after weighting by control
values, from desiccation experiments with groups of 10 eggs each.

ms | De

ay) | | of | Fan On Fan Off
Rie | | . | ——— 5525
Dr | nn eee | Hours* Maori Perey Hours* eos Hatch Dis
| о о /0 /0
NS AOL i) 2:95 90 73 2-0 100 100
Newly! 20 (5:30)** 33 87 4-25 77 100
| laid | 30 7-0 0 (31%)*** 0 7-0 12 100
| ele 40:1 | 6255 0 0 8-6 0 0
60 = = ES 0 0
90 | -—- - == -—— | -
10° | 2-0 100 AN 99 100
|. 20 5-75 95 86 6-0 100 88
| | 30 | (6:5) 100 (33%) 95 7-0 100 (31%) 100
пе ADMIN = = =) ion 100 100
| | 50 1-5 100 88 | 12-0 100 100
| 60 6-2 90 88 7-1 80 (63%) 88
77 = a = = 50 100
| a | > =
| 210 0-33 100 100 0.6 100 88
| | 20 0-85 77 100 | 1-0 100 100
Newly) 30 1-3 100 100 1-2 84 0
| аа | (also control)
40 2-0 100 100 1-8 100 (43%) 100
50 2-4 72 (54%) 100 2-25 78 31
60 (1-9) 100 100 2-0 88 0
i 70 3-25 66 63 2-0 55 38
50 nah 2 a E PE ee an E ER
10 0-4 100 100 | 0-4 100 100
20 0-7 100 88 0-75 100 88
| We SOF ls 100 44 1-3 95 93
| | 40 | (1:6) 100 (41%) 100 1-75 100 96
VO alk Bye — = 2-1 90 100
60 2.15 100 75 (>2-0) 88 96
70 2-25 80 100 2-7 80 100
ЗО 2.9 44 100

4 96

* Hours, expressed in the decimal system, refer to the time taken to reach the requisite weight.
** —Time taken is in doubt.
*** — weight loss not exactly coinciding with the desired loss.
When viability of the control was 100%, viability of the desiccated eggs was taken as valid.

When hatchability of the desiccated eggs was the same as the viability of the desiccated eggs, the
hatchability of the desiccated eggs was taken as 100°4. Some experiments were duplicated and in those
cases the mean values have been taken. In occasional cases of doubt as to viability and hatchability the
value given is the mean of the 2 doubtful limits.

RESULTS 1. Rate of weight loss
The rate at which the eggs lost weight
The results are presented in Table I, and (considered to be due to loss of water)

discussed below. was calculated from the experimental data.

SURVIVAL OF AGRIOLIMAX AFTER DRYING 395

TABLE 2. Summary of 3 statistical tests comparing the influences of different factors (paired) on
the rates of weight loss (mg/hour).

| A
Variance ratio | Students t | Fisher-Behrens |
| | A «gs
Variables Compared == - | | Significance
E p t p d p
Fan on/fan off | 1-100 >0-05 0.2110 >0-8 | — — | попе
Newly laid eggs/stage У }:713 0-05 | 2-261 ~0-05 - — none
eggs—at 90% R.H. |
Newly laid eggs/stage У 6:353 < 0-05 = a | 50202742 О ее
eggs—at 50% В.Н. | >0-01 |
| |
Newly laid eggs/stage V 1.034 0-05 0-1698 >0-8 | none
eggs— all experiments
50% R.H./90% R.H. 17:66 < 0-01 — —- 8-5859 < 0-001 very high

* Eggs grouped/eggs 3-065 >0-05 | 8-200 <0-001 | 2-746 <0-02 | high
dried singly < 0-1

* For this comparison the rates were calculated as mg/egg/hour. It was necessary to use experiments
in which more than 50% of the weight was lost; however only experiments common to both * grouped ”
and * single * conditions were used.

Earlier experiments (Bayne, 1967) had not have been detectable with the present
shown that the rate of drying of A. experimental procedure (Bayne. 1968).
reticulatus eggs was almost constant to The relative humidity of the surrounding
50%, of the weight loss. For comparison air however has a very significant effect
of drying rates, therefore, data were taken upon desiccation rate. Finally it is clear
only from experiments which involved loss that the habit of laying eggs in clusters
of from 10 to 50% of the weight. Any rather than singly must have a marked
experiments which were not repeated effect on the drying rates of eggs in the
identically with ‘fan on’ and ‘still’ condi- middle of the bunch if the relative humi-
tions were excluded. The effects of dity falls to less that 100%. In these
various factors on the drying rates were experiments grouping of eggs on the
then examined statistically (Table 2) balance pan significantly retarded the
using the procedures detailed by Bailey desiccation rates.
(1959).

It is seen that air movements caused by 2. Survival
the fan were insufficient to cause a signifi-
cant increase in the desiccation rate, at Figure 3 has been constructed from the
least with groups of 10 eggs. Also. unlike hatchability data in Table 1. Although
many insect eggs (Browning, 1953), the not all the eggs surviving a desiccation
rate of drying was the same in Agriolimax experiment hatched, there appeared to be
for both newly laid eggs and eggs contain- no additional (delayed) effect acting
ing well developed embryos. But rate to depress hatchability. If there had been

differences due to age would probably such an effect, it would have been mani-

396 si CHRISTOPHER J. BAYNE

HAT CG Haar Bet ar ov

Newly laid Stage V
ge

100 100
>
= 60
= 60 90% ГВ
Fo)
eo
о 20 20
o
=
re 100 100
(=
o
С 60 60 50%rh
Ф
a

20 20

20 40 60 80 20 40 60 80
ple) ie ce 7ein) 1 Wiel ое ¡MOSES
Vode АВЕ ПУ
Newly laid Stage V

20 40 60 80

рее gO Ch ie а “loses:

FIG. 3. Hatchability of newly laid and stage У eggs after desiccation at 90% and 50% relative humidity
(from data in Table 1). The method for calculation of the plotted values in given on page

. FIG. 4. Viability of newly laid and stage У eggs after desiccation at 90% and 50% relative humidity.
The dots represent results from experiments with 10 eggs (Table 1), and the vertical bars represent the
upper lethal limits estimated from experiments with single eggs (Table 3).

SURVIVAL OF AGRIOLIMAX AFTER DRYING 397
TABLE 3. Viability of Agriolimax reticulatus eggs desiccated singly,
Er | ы Fan Оп | Fan Off Estimated
(0) /0 = = — = = = a р
Relative Egg | Weight a oe | ao E | Upper el
Humidity | Stage | loss Hrs* ont Hrs* | ME ne | non,
4% Se E des. con. : des. con. % wt loss)
о | 55 и 2-7 |
I 5505 A esa) Se 2-9 |
a Ro:
laid | 60 | 3-5 + 3-25 ? 60-65
a 3-5 о |
| 70 4.25 | о + 50 O {
70 | 3.8 0 |
ee ES 1 E EE nee.
| N ME En
70 | 42 = - |
76 6:5 о 4 |
V CLAIR ra. fo | 7458 | мА 76-79
80 | 4-4 | o se
80 | 608 „| 50 +
= — == | = ae = = == =
TO epee le? о + 1-0 |
Newly! 70! | 1-0 ar ue |
laid) | 80: | 125 | vo + 1-4 o т 69-75
| 80 A 250 er
50 | — | | — -
70 0-9, | | MR
| A E : |
У 75 1-25.) Е + 1.3 + 76-79
or er | о - д о р
84 25 | о + |

* Hours, expressed in the decimal system, refer to the time taken ¿0 reach the percentage weight loss

. indicated.
des. = desiccated + = viable
con.=control o = dead

fested most clearly near the upper lethal
limit.

For this reason viability data only are
presented in Table 3, for experiments
involving the drying of individual eggs.

These data permit an estimate of the
upper lethal limit to within a few percent.
Since the proportions of the shell and jelly
layers vary somewhat between eggs, this
upper limit (a percentage drying value)
is subject to individual variation of a few
per cent. Such variation would be in
addition to physiological variation between
embryos. The estimates of upper lethal

limit are thus probably as nearly accurate
as they can be.

In Figure 4, the ranges of weight loss
over which death of individual (single)
eggs occurred (vertical bars, taken from
Table 3) are superimposed upon the
viability data for groups of 10 plotted from
Table I. The discrepancy between the
upper lethal limits for newly laid eggs at
90% В. H. (30% vs. 60-65% weight loss)
arrived at by the 2 procedures is un-
resolved; it is hoped that further work will
clarify the reasons for the difference.
Since the experiments involving 1° egg

398 CHRISTOPHER J. BAYNE

were of a more critical nature than those
involving 10, the indicated limit of 60-65%,
is probably valid. In the other 3 classes
(1.e., newly laid eggs at 50% and stage У
eggs at 50% and 90% R.H.) the values
obtained in both series of experiments
agree more closely.

Effect of humidity

The newly laid eggs are able to survive
more drying at 50% В.Н. than at 90%,
whereas no difference was found with the
older eggs. In these experiments eggs
were transferred to moist conditions as
soon as the required weight loss had
occurred. Drying was more rapid at the
lower humidity, so that exposure of the
embryo to the dry conditions was for a
shorter duration, and this may have been
responsible for the greater survivial at
50% В.Н. It is also possible that at
this rate of drying the degree of hydration
in the outer and inner regions of the egg
are further from equilibrium at any one
time than at the slower rate. Thus the
embryo, located towards the centre of the
egg, may be exposed to less dehydration at
the lower humidity.

Effect of age

At both relative humidities the advanced
embryos were more tolerant of de-
hydration than the newly laid embryos.
Determinations of the dry weights of eggs
from both age groups gave very similar
values. Newly laid eggs had an average
dry weight of 10.2% and stage У eggs of
9-6%. This difference is not significant
(P test p>0-1). Since stage У embryos
occupy a considerable volume of the egg
(Fig. 1), it is clear that the dehydration
experienced in these experiments must have
resulted in the loss of some water from
the embryos.

DISCUSSION

-- Weight cycles due to variations in the

degree of hydration were shown to be
normal phenomena in terrestrial snails and
slugs as early as 1934 (Howes & Wells).
A high degree of tolerance to desiccation
has been reported for several adult
gastropods; a highly hydrated Limax
tenellus has been reported to survive 80%,
weight loss (Kunkel, 1916), Australorbis
glabratus а 70% loss (von Brand,
McMahon & Nolan, 1957), and Helix a
58% loss (Kunkel, 1916). Brown (1961),
Kensler (1965) and Emerson (1965) con-
sidered desiccation tolerance in relation to
vertical distribution on the sea shore. The
latter author reported 50% survival of
Littorina scutulata at about 65% water
loss. However, a value as low as 14%,
water loss was sufficient to cause 50%,
mortality in Calliostoma ligatum (Emer-
son, 1965). The pulmonate Ovatella
myosolis was one of the most susceptible
species of intertidal invertebrate studied
by Kensler (1965). There is thus a
considerable degree of variation in resis-
tance to desiccation in gastropods. Few
papers mention desiccation survival of
adult slugs. However, Getz (1959) and
South (1965) both found that Agriolimax
(Deroceras) reticulatus survived dry
conditions better than various Arion
species despite the very much thinner body
wall of Agriolimax.

The ability of capsule-bound embryos of
gastropods to survive considerable water
loss now seems well established. Reports
in the early literature (e.g., Binney, 1878)
of successful development of oven-dried
eggs when transferred to moist conditions
was unacceptable to Carrick (1942) and
to Arias & Crowell (1963), and in the light
of results presented by Carmichael &
Rivers (1932), Karlin & Bacon (1961),
and by the present author (this paper),
those early reports seem to be clearly
disproven. Recently Wolda (1965)
talking of Cepaea nemoralis reported that
‘draught kills eggs rather rapidly.” Gugler
(1963) claimed that various snail eggs,

SURVIVAL OF AGRIOLIMAX AFTER DRYING 399

after drying out, continued to develop
when remoistened. but Karlin & Bacon
(1961) showed that Limax maximus eggs
did not; in neither of these 2 cases was the
amount of drying specified.

The striking feature of the present
results is the great amount of water loss
which was tolerated. This tolerance
contrasts with that shown by the egg of
the cricket Gryllulus commodus, which is
killed by 20-30%, loss of weight (Browning,
1953).

Carmichael & Rivers (1932), working
with the slug Limax flavus, reported a
survival of 85%, weight loss by some eggs,
a value higher than any reported in the
present paper. If percentage dry weight
values of Limax are similar to those found
in Agriolimax, as they are likely to be,
the reported value would mean that only
about 5% of the water was left in the
egg when desiccation was ended. These
authors further found that, when the eggs
had lost 65°, of their original weight just
prior to hatching, the embryos had lost
35-40% of their weight. It may be
significant that a large part of the volume
of the stage Y embryo consists of peri-
vitelline fluid in the digestive canal and
hepatic lobe (Carrick, 1939). Yon Brand
et. al., (1957) and Emerson (1965) report
that. in dehydrating snails, the percentage
of water lost from the tissues (excluding
blood) is considerably less than that lost
from the whole animal. А similar ability
to keep the tissues hydrated may occur
in advanced embryos of slugs. It would
have been very interesting to know what
percentage of weight loss was due to
extra-embryonic material, and what per-
centage to dehydration of the embryo т
Agriolimax reticulatus, but the small size
of these eggs made such an assessment
impossible.

Carmichael & Rivers (1932) found a
greater tolerance by the younger Limax
eggs; whereas 1 found the younger eggs of
A, reticulatus to be more susceptible,

Walton (1918) and McCraw (1961) report
that embryos of Lymnaea become more
susceptible to drying as hatching is
approached. However the increased tol-
erance of the later developmental stages
which was found in the present work was
paralleled by the results of Arias & Crowell
(1963), also working with Agriolimax,
in which a greater tolerance to high and
low temperatures was observed in more
advanced embryos. Similarly, Chroscie
chowski (1962) noted a greater desiccation
tolerance in more developed eggs of
Biomphalaria.

Carmichael & Rivers (1932), in contrast
to the present results, reported that the
age of the Limax embryo affected the rate
of desiccation. Their experiments did
not involve control of physical conditions,
and moreover would not be expected to
detect rate variations due to the
characteristics of the eggs (Bayne, 1968).

Further information would be of
interest. Keeping eggs partially dehydrat-
ed for varying periods before returning
them to moist conditions could be used to
investigate whether or not the embryos
can become acclimated to water loss (Segal,
1961). In view of reports by Walton and
McCraw (see McCraw, 1961) that partial
drying of egg masses of Lymnaea
prolonged the hatching process, such an
effect should be investigated in terrestrial
species. The view of the present author
is that hatching 1$ neither delayed nor
prolonged by drying in Agriolimax. И
would also be of interest to obtain desic-
cation survival values for an aquatic
species. Bretschneider (1948) mentions
Neumann’s finding that “ Limnaea” egg
masses could survive 95 minutes of
exposure to the air. but the work was
unfortunately not quantitative.

ACKNOWLEDGEMENTS

It is my pleasure to acknowledge the encourage-
ment of Dr. N. W. Runham, who with A. A. Lar-
yea, also gave helpful advice. Drs, P. O’Donnald

400 CHRISTOPHER J. BAYNE

and B. L. Bayne advised oni statistical analysis and
the latter on presentation; my wife helped prepare
the illustrations. I am grateful to Professor
Е. W. Rogers Brambell, C.B.E., F.R.S. for provid-
ing research facilities, and to the Commonwealth
Scholarship Commission for the provision of a
research award.

LITERATURE CITED

ARIAS, В. О. & CROWELL H. H., 1963, A
contribution to the biology of the grey garden
slug. Bull. S. Calif. Acad. Sci., 62: 83-97.

BAILEY, N. T. J., 1959, Statistical Methods in
Biology. The English Universities Press Ltd.,
London.

BAYNE, C. J., 1966, Observations on the com-
position of the layers of the egg of Agriolimax
reticulatus, the grey field slug. Comp. Biochem.
Phvsiol., 19: 317-338.

1968, A study of the desiccation of egg capsules
of eight gastropod species. J. Zool., Lond.,
155: 401-411.

BINNEY, У. G., 1878, The terrestrial air-breath-
ing mollusks. Bull. Mus. comp. Zool., Harvard,
4:1.

BRETSCHNEIDER, L. H., 1948, The mechanism
of oviposition in Limnaea stagnalis L. Proc. K.
ned. Akad. Wet., 51: 616-626.

BROWN, A. C., 1961, Desiccation as a factor in-
fluencing the vertical distribution of some
South African gastropods from intertidal rocky
shores. Port. Acta. biol. 7B(1-3): 11-23.

BROWNING, T. O., 1953, The influence of tem-
perature and moisture on the uptake and loss
of water in the eggs of Gryllulus commodus
Walker (Orthoptera: Dryllidae). J. exp. Biol.,
30: 104-115.

CARDOT, H., 1924, Observations physiologiques
sur les embryons des gastéropodes pulmonés.
J. Physiol. Path. gen., 22: 575-586.

CARMICHAEL, E. B. & RIVERS, T. D., 1932,
The effect of dehydration upon the hatchability
of Limax flavus eggs. Ecology, 13: 375-380.

CARRICK R., 1939, The life history and develop-
ment of Agriolimax agrestis L., the grey field
slug. Trans. К. Soc. Edinb., 59: 563-597.

— 1942, The grey field slug, Agriolimax
agrestis L., and its environment. Ann. appl.
Biol., 29: 43-55,

CHROSCIECHOWSKI, P., 1962, Observaciones
en el laboratorio y en el campo raso sobre la
rezistancia al desecamiento de algunos gastero-
podos Venezolanos, especialmente del huesped
intermediario de la Esquitosomiasis mansoni.
Revta Venez. Sanid. Asist. Soc., 27: 159-178.

EMERSON, D. N., 1965, Tissue hydration during
desiccation of three species of intertidal pro-
sobranch snails. Rep. Ат. malac. Un.: 52-53.

FISHER, R. A. & YATES, F., 1953, Statistical
tables for biological, agricultural and medical
research. Oliver & Boyd, London.

GETZ, L. L., 1959, Notes on the ecology of slugs:
Arion circumscriptus, Deroceras reticulatum,
and D. laeve. Am. Midl. Nat., 61: 485-598.

GUGLER, C. W., 1963, The eggs and egg-laying
habits of some mid-western land snails. Trans.
Kans. Acad. Sci., 66: 195-201.

HOWES, N. H. & WELLS, G. P., 1934, The
water relations of snails and slugs. II. Weight
rhythms in Arion ater L. and Limax flavus L.
J. exp. Biol., 11: 344-351.

KARLIN, E. J. & BACON, C., 1961, Courtship,
mating, and egg laying behaviour in the Lima-
cidae (Mollusca). Trans. Amer. microsc. Soc.,
80: 399-406.

KENSLER, C. B., 1965, Ecological studies of
intertidal crevice fauna. Ph. D. thesis, Univer-
sity of Wales.

KUNKEL, K., 1916, Zur Biologie der Lungen-
scnecken. Winter, Heidelberg.

McCRAW, B. M., 1961, Life history and growth
of the snail Lymnaea humilis Say. Trans.
Amer. microsc. Soc., 80: 16-27.

SEGAL, E., 1961, Acclimation in molluscs.
Amer. Zoologist, 1: 235-244.

SOUTH, A., 1965, Biology and ecology of
Agriolimax reticulatus (Mull.) and other slugs:
spatial distribution. J. Anim. Ecol., 34:
403-417.

VON BRAND, T., MCMAHON, Р. & NOLAN,
M. O., 1957, Physiological observations on
starvation and desiccation of the snail Austra-
lorbis glabratus. Biol. Bull., Woods Hole, 113:
89-102.

WALTON, 1918, Jn: McCraw, B. M. (1961).

WOLDA, H., 1965, The effect of drought on egg
production in Cepaea nemoralis (L.). Archs.
néerl. Zool., 16: 387-399,

SURVIVAL OF AGRIOLIMAX AFTER DRYING 401

RESUME

LA SURVIE D’EMBRYONS D’AGRIOLIMAX RETICULATUS,
SUIVANT LA DESSICATION DES OEUFS

C. J. Bayne

Des embryons d’Agriolimax reticulatus peuvent survivre а une perte de poids de 60 a
80% a partir des oeufs. Les embryons agés sont moins tolérants а la dessication que
les jeunes. Les oeufs fraichement pondus sont moins sensibles quand la dessication
intervient plus rapidement, c.a.d. quand ils sont exposés 4 une humidité relative de 50%
au lieu de 90%. La dessication ne semble pas avoir d’effets ultérieurs sur la viabilité
des embryons.

Les oeufs d’äges differents perdent du poids аи méme taux, mais leur groupement
provoque une diminution significative du taux par rapport a celui des oeufs desséchés
isolément; les oeufs de l’exterieur se deshydratent plus rapidement que ceux du centre.

RESUMEN

SUPERVIVENCIA DE EMBRIONES DE LA BABOSA GRIS DE
CAMPO AGRIOLIMAX RETICULATUS, DESPUES DE LA
DESECACION DEL HUEVO

C. J. Bayne

Embriones de Agriolimax reticulatus sobrevivieron una pérdida de peso de 60 a 80%
рог deshidratacion de los huevos. Embriones avanzados fueron más tolerantes que
los embriones muy jovenes. Huevos recien puestos fueron menos susceptibles cuando
la desecacion ocurrió rápidamente, por ejemplo a 50% de humedad relativa comparada
con 90%. La desecación pareció no tener efecto en el desarrollo de los embriones.
Huevos depositados temprano, y los recién puestos perdieron peso a la misma velocidad
pero, cuando estaban agrupados en proceso fue más lento que en los aislados: los de
la periferia del grupo se deshidrataron más rápido que los del centro.

ABCTPAKT

ВЫЖИВАНИЕ ЭМБРИОНА СЕРОЙ ПОЛЕВОЙ УЛИТКИ
AGRIOLIMAX RETICULATUS ПРИ ВЫСЫХАНИИ ЯЙЦА

К, Ж. БЭЙН

Было обнаружено, что эмбрионы Agriolimax reticulatus выживают при потере
веса яйца (благодаря дегидрации) на 60-80%. Более развитые эмбрионы бо-
лее выносливы к высыханию, чем очень молодые, Вновь отложенные яйца бо-
лее выносливы к более быстрому высыханию при 50% относительной влажнос-
ти, по сравнению с 90%. По-видимому, высушивание не оказывает замедляю-
щег действия на выживаемость эмбрионов.

Яйца обоих возрастов теряли вес с одинаковой скоростью, но при соби-
рании их в группы наблюдалось значительное замедление этой скорости, по
сравнению с яйцами, высушиваемыми по отдельности. Яйца, находящиеся сна-
ружи группы, высыхали быстрее, чем бывшие в середине,

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MALACOLOGIA, 1969, 9(2): 403-419

SOME ENVIRONMENTAL EFFECTS ON THE LARVAL
DEVELOPMENT OF LITTORINA PICTA (MESOGASTROPODA),
REARED IN THE LABORATORY

Jeannette W. Struhsaker! and John D. Costlow, Jr.

Duke University, Marine Laboratory, Beaufort,
North Carolina, U.S.A.

ABSTRACT

The results described are from a general study of population ecology and intraspecific
shell variation of Hawaiian Littorina picta. Larvae from snails of two extreme types of
shell sculpture populations and an intermediate shell sculpture population were reared
under constant laboratory conditions and their differences in shell morphology, growth,
and mortality assessed. These differences are assumed to reflect genotypic variation.

The laboratory conditions for rearing larvae are outlined and several experiments
leading to the determination of these conditions are discussed. The major environmental
factors studied were the effects of antibiotics, food, salinity, temperature, and substrate
on larval growth and mortality. In general, rearing conditions for all sculpture types
are similar. The highest growth and survival are obtained when larvae are reared in
sea water within a salinity range of 35-40 о/оо and temperature range of 24-25°C,
treated with 20-25 ppm of Polymixin B sulfate and fed Phaeodactylum tricornutum.
The mortality of laboratory-reared larvae was in general very high. The maximum
survival to settlement obtained was approximately 50%; through metamorphosis, 10%.
The average survival through metamorphosis, however, was only about 1%. The
laboratory conditions, therefore, may not provide the most optimal environment for the
larvae.

There are variations in the growth and mortality of different sculpture types at the
salinity-temperature extremes. These are correlated with the distribution of sculpture
types in the natural environment. Heavily-sculptured shell forms occurring on drier,
low wave action substrata have larvae which are more resistant to high salinity and less
resistant to low temperature than the larvae of smooth shell forms which occur on wet
substrata with strong horizontal wave force. All types of larvae settle on a surface
covered with an algal film. Another major stimilus to settlement is probably the inter-
mittent removal of water from the bowl after approximately 3 weeks of development.
The above environmental factors are discussed in relation to their importance in mortality
of larvae and post-veligers in the natural environment.

INTRODUCTION

Only a few planktotrophic gastropod
larvae have been reared through meta-
morphosis in the laboratory. They
include the reogastropod larvae of Nas-
sarius obsoletus and N. vibex (Scheltema
1961, 1962a, 19625) and Strombus gigas
(D’Asaro, 1965). Recently, a number of

gastropod larvae have been reared by
Fretter & Montgomery (1968). At
present, little is known of the environ-
mental factors affecting the development
of planktotrophic larvae. Some of the
more important studies are those of
Scheltema (1961, 19625, 1965, 1967) and
Paulson & Scheltema (1968) on the effect
of substratum, salinity, temperature and

* Present address: Hawaii Institute of Marine Biology, University of Hawaii, Box 1067, Kaneohe,

Hawaii, U.S.A.

404 JEANNETTE W. STRUHSAKER AND JOHN D. COSTLOW, JR.

food on development of Nassarius larvae.
Fretter & Montgomery (1968) have studied
the food and feeding of many other
marine prosobranchs. Most prosobranch
larvae successfully reared through meta-
morphosis have been those with short-
er planktotrophic larval stages (e.g.,
Crepidula; Conklin, 1897). Many meso-
gastropod larvae, such as Littornia are
often more difficult to rear because of
their relatively long planktotrophic lives
(several weeks) and consequently, little is
known of their ecology.

In contrast to the few studies on rearing
planktotrophic gastropod larvae, there
have been a large number on rearing of
marine bivalve larvae. Most of these
are summarized and discussed by Loosa-
noff & Davis (1963) and Walne (1964),
whose work has beer of particular value.
Ecological studies of marine larvae are,
in general, rare. especially quantitative
studies of the effect of environmental
factors on morphology and physiology of
larvae. Among the few such investi-
gations are those of Costlow, Bookhout &
Monroe (e.g., 1960, 1962) on the effect
of salinity and temperature on develop-
ment, growth and mortality of various
species of crab larvae.

The following results are part of a
general study being made of intraspecific
variation and population ecology of
Hawaiian Littorina. The relationship of
larval development studies to the basic
problem of the origin of shell variation
and details of the morphology and
behaviour of larvae are discussed else-
where (Struhsaker, 1968; Struhsaker &
Costlow, 1968). Shell sculpture variation
in Г. picta is apparently related to
physiological variation in resistance to
desiccation and extreme salinity. Smaller,
smooth-shell forms (with lessresistance to
desiccation and high salinity) inhabit
supratidal areas with heavy horizontal
wave force and wet conditions. The
larger, heavily sculptured forms (with

higher resistance to desiccation and high
salinity) occur in supratidal areas with
slight horizontal wave force (mostly spray)
and drier conditions. Intermediate shell
forms occur in intermediate habitats.
The total sampled Oahu population shows
a bimodal distribution of shell type with
most of the total population either smooth
forms or heavily sculptured forms; there
are fewer intermediate forms. The bi-
modal distribution and other evidence
suggests that L. picta may exhibit an
example of adaptive polymorphism, the
variation in shell sculpture being associated
with varying topography and wave action
on different substrata. The 2 poly-
morphic population extremes may have
originated from disruptive selection by
various wave forces and moisture condi-
tions within the heterogeneous supratidal
habitat of the Hawaiian Islands (Struh-
saker, 1968).

In larval studies, the larvae from parents
of extreme types of shell sculpture were
reared under constant laboratory condi-
tions. The significant and consistent
morphological and physiological vari-
ations of larvae reared under these
conditions were assumed to indicate
genotypic variation between the shell
forms (Struhsaker, 1968). In the follow-
ing study, the rearing conditions and the
experiments leading to their definition are
described. The environmental factors
found most important to larval develop-
ment and thus of primary interest were:
previous history of parental snails, disease
(bacteria and fungi) food type, food
concentration, larval concentration, sali-
nity, temperature, and substratum at
metamorphosis.

MATERIALS AND METHODS

Copulating pairs of Littorina picta were
collected at full moon periods during
flood or ebb of the tide. The copulating
male and female were separated and

DEVELOPMENT OF LITTORINA 405

placed into labeled plastic bags (no water).
The best results in larval rearing experi-
ments were obtained by placing females
in individual spawning dishes within 2
days after collection. Methods Гог
analyzing and describing spawning, spawn-
ing periodicity and fecundity were
described previously (Struhsaker,
1966).

The rearing conditions are as follows:

|. Rearing containers: Straight-sided
stacking dishes (4 inch and 10 inch
diameters). Larger containers can be
used, but larvae are more difficult to
locate and tally.

2. Volume of sea water: With larvae
and food at appropriate concentrations,
1°40 liters in 10 inch stacking dishes and
0:25 liters in 4 inch stacking dishes. In
general, larger volumes give best
survival.

3. Filtration: Cuno Filter (Aqua-pure
water filter with cartridge No. P110, Cuno
Engineering Corporation, Meriden, Con-
necticut). The Cuno filter removes most
particles above 10 microns in diameters. It
is composed of non-toxic cellulose fibers
and filters water rapidly (approximately 5
gallons/5 minutes, with gravity flow).
Filter cartridges, if reused, should be
washed immediately after use and dried
in the sun. Ideally, new cartridges should
be used for each filtration because fungus
may accumulate in cartridges. If allowed
to age in the dark (for 2-4 weeks), filtered
sea water does not need the treatments
Nos. 4 or 9 below and gives very satis-
factory results.

4. Sterilization of sea water: Ultra-
violet light (apparatus designed after
Loosanoff 8 Davis, 1963). Water must
be filtered before running through the
UV light unit and antibiotics not added
until after the treatment (see p 13).

5. Sterilization of apparatus: Soak in
50 ppm of Combistrep (Charles A. Pfizer
& Co., Inc., New York, N.Y.) in distilled
water for 12 hours. After treatment, all

apparatus should be carefully washed with
a pressure nozzle.

6. Salinity: 35 to 40 ppt.

8. Light: Approximately 12 hours light,

12 hours dark.
** Examolights, ” MacBeth Daylighting
Corporation; approximately 100 foot-
candles at surface. This approximates
Х10 ' of the intensity of light over the
surface of the ocean. Higher light inten-
sities should be avoided because they
promote high rate of algal growth which is
harmful to larvae.

9. Antibiotics: Polymixin B, 20 to 25
mg/liter sea water (20 to 25 ppm). This
treatment results in good survival and
does not affect growth rate significantly.
Combistrep, 0°2 cc (50 mg/liter sea water
=50 ppm) reduces mortality greatly if
larvae are transferred to treated water
only after larval shell is developed and the
larvae have hatched from the capsule.
Larvae should then be treated only at
critical moments, as Combistrep may affect
the growth rate.

10. Larval concentration: 250 larvae/
1°40 liters; 50 larvae/0°25 liters. Concen-
trations over 0°5 larvae/ml reduce growth
rate significantly.

Il. Food type: Phaeodactylum tri-
cornutum, a diatom, Algae are most
conveniently cultured in Erlenmeyer
culture flasks (2°8 liters) filled with Cuno-
filtered sea water. Add | cc each of
Nutrient A and Nutrient B per liter of
sea water (see Loosanoff & Davis, 1963 for
ingredients) plus 0°56 cc Combistrep/
2°8 liters sea water (50/liter=50 ppm).
Air is continually bubbled into the flasks
which are maintained at 19-20°C in
constant temperature cabinets. Lights
used are the same as above (8). New
cultures are started every 2 days.

12. Food concentration: Approxi-
mately 10? algal cells/ml. Concentration
of algal cells is determined by hemocyto-
meter counts or a Coulter counter. New

406 JEANNETTE W: STRUHSAKER AND JOHN D. COSTLOW, JR.

algae are added to appropriate con-
centration after every water change. It
is very important not to overfeed the
larvae.

13. Water change: Daily for first 7
days, then every 2 days; when large
number of larvae, through sieve; when
small number, by hand pipetting.
Changes are made with a stainless steel
sieve, using 0°44 mm of the U.S. Standard
Sieve Series, Newark Wire Cloth Co.,
Newark, N.J.

14. Settlement Substratum: From app-
roximately day 21, larvae are introduced to
1°40 liter stacking dishes which are
covered with a thin layer of alga or
detritus. This film of food must be
present for metamorphosis to occur.
To grow algal film, pieces of appropriate
alga, 1°0 liter of filtered sea water, and |
cc/liter of Nutrient A and | cc/liter of
Nutrient В (see 11) are introduced into
stacking dishes. Bowls are then placed
in constant temperature cabinets with
same conditions used to grow Phaeo-
dactylum tricornutum (11). The addition
of small rocks from natural substratum
(must also be covered with algae or
detritus) may also promote settlement.
All other possibly competing organisms
must be carefully removed. For Littorina,
tilting the finger bowls on a rack so that
half the bowl is submerged and half
above the water seems to stimulate
esttlement.

Photomicrographs and larval counts
during larval development were taken at
3 or 7 day intervals. Measurements were
made from negatives.

Most experiments were done using the
eggs from a single female of intermediate
population shell type. except for the
salinity-temperature experiments where
the 2 extreme types were contrasted
(Struhsaker, 1968).

Factorial and multiple regression analy-
ses were performed with the aid of an
IBM 7040 computer.

RESULTS
Previous history of parents

There is considerable variation among
larvae of Littorina victa prior to hatching
from the capsule. This variation occurs
among the larvae of an individual female
and larvae of females from а single
population (or sculpture type). There are
diverse sizes of spawns, larval sizes at
hatching, percentages of abnormal larvae
spawned and viabilities of larvae. Deter-
mining which of these variations are
attributable to the previous environmental
history of parents and which to inherent
genetic variability is still an unsolved
problem.

An individual female may spawn several
successive days (Struhsaker, 1966). The
number of eggs per spawn will differ
greatly between the days (from approxi-
mately 10-1,000 eggs). The reason for
this variation is unknown. The number of
abnormal larvae may be greater on one
day than another. For example. the Ist
day's spawn often contains a higher
percentage of abnormalities than do later
spawns. This could be induced by some
environmental factor (e.g. extremes of
temperature or desiccation) affecting the
eggs while they are still in the female
genital tract and in the first polar stage of
Metaphase I. Viability of larvae from a
single spawn may also vary; some larvae
seem never to feed and to die within a
few days after hatching, while others feed
normally and survive to metamorphosis.
Because the larvae were treated alike and
given abundant food, the differences may
indicate genetic variation in viability.
Females of a single population also show
the variations described above but the
range of variation 1$ greater.

The results of experiments in which
several morphological. physiological and
behavioral traits of different shell sculpture
populations were contrasted are summa-
rized elsewhere (Struhsaker. 1968). There

DEVELOPMENT OF LITTORINA 407

EIG. 1.

Normal and abnormal larvae at hatching (3 days);

ae ee - RE:

A, normal protoconch (without larva);

B, abnormal larva (without protoconch). Only a small cap of shell present (arrow). Empty capsule

at left.

are significant differences, probably
genetic, between larvae of extreme scul-
ptured ard extreme smooth shell
populations. These differences include
larval size, growth rate, shell sculpture and
viability.

Abnormalities

Abnormal larvae were often observed
during the larval experiments. The most
common type is a larva with an abnormally
incomplete protoconch at hatching.
Normal larvae have fully-developed
protoconchs at this time (Fig. 1-А). In
several experiments most of the larvae
hatched with only a small piece of shell
on the visceral hump (Fig. 1-B). Proto-
conch development varied from this
extreme of a small cap of shell to a

protoconch nearly normal in size, enclos-
ing most of the larva. Several environ-
mental factors produce this shell
abnormality; overcrowding (more than
300 larvae/0°25 liters), fungal
contaminations and application of
certain antibiotics (particularly Combis-
trep) during the first 3 days of early
development before hatching. The
mechanism by which this abnormal shell
development is induced is unknown.
Larvae with incompletely developed
protoconchs usually die within 4 to
5 days after hatching.

Another type of abnormal larva has an
incompletely developed body with a
large space between the larva and proto-
conch, while normal larvae always fill the
protoconch. This abnormality has not

408 JEANNETTE W. STRUHSAKER AND: JOHN D. COSTLOW, JR.

TABLE 1. Factorial analysis of variance. The effect of time, antibiotic and antibiotic concentration
on mortality of larvae. Three weeks x4 antibiotics «2 concentrations per antibiotic х2

replications.

Only significant main effects and interactions shown. Each treatment com-

bination consists of 2 replicates (г) or 2 bowls of larvae (65 larvae/bowl).

Source Ss Df

Week (w) 115515255 1
Antibiotic (a) 5,435:56 3
Concentration (c) 382:95 1
Week-Antibiotic (wa) 1,270:14 3
Week-Concentration (wc) 1255237, 1
Antibiotic-Conc. (ac) 708-57 3
wac 1,394 -36 3

Error (wacr) 7:66

Mean square

F ratio

Df Probability

11,515-55 4,515-90 1,3 ГС 0-01
1,811-85 710-53 33 1<< 0-01
382-95 150.18 13 F<0-01
423-38 166-03 1,3 1< 0-05
125-37 49-16 3,3 10:01
236.19 92162 a ГС 0-05
464-79 182-27 3,3 P<0-01

2-55

been definitely correlated with any
environmental factor. It appears more
common in day | spawns than in later
spawns from the same female. It may also
be induced by extremes of environment
while the eggs are in the early stages in the
female genital tract.

Occasionally, unusual early develop-
mental stages and capsules are observed.
The embryos are smaller than normal and
fail to differentiate beyond a late cleavage
stage or do not differentiate at all. The
outer capsules are often aberrantly-
shaped and contain more than one of these
embryos. This abnormality occurs in
spawns of females exposed to long periods
of desiccation (more than a month). In
most cases, abnormal early stages are rare.
Females, although desiccated for long
periods, usually still spawn normally.

Some larvae, otherwise appearing
normal, do not feed, and die within a few
days from hatching. This may result
from incomplete development of the
intestinal tract.

Diseases

Both marine bacteria and fungi have
deleterious effects on larval development,
the degree depending upon the larval stage
and the concentration of the disease
organisms. Ordinarily, at low concen-
trations, neither bacteria nor fungus will

kill larvae, particularly when the larval
protoconch is fully formed and the water
changed daily. Earlier stages are more
susceptible to disease. Anothergener ali-
zation is that the bateria and fungi are
more deleterious in smaller volumes of sea
water. This. may be due to the
proportionately greater surface area
suitable for bacterial growth (Zobell,
1946). Diseases are of considerable
importance to the success of rearing larval
littorines in small laboratory containers,
but their importance as a mortaility factor
in the natural planktonic environment is
uncertain.

In most experiments no identifications
of bacteria or fungi were made and no
studies made of the mechanism by which
they affect the larvae. However, several
types and concentrations of antibiotics
were tested. Many of these increase
survival of larvae. particularly when the
treatment is applied after the protoconch
is formed. Antibiotic treatment before
hatching may result in larvae’ with
abnormal shells. Some of the antibiotic
treatments dramatically decrease growth
rate: most do not. Still other antibiotics
seem to produce an accumulative toxic
effect.

The results of a factorial experiment
with continual antibiotic treatment are
summarized in Table 1. All factors were

DEVELOPMENT OF LITTORINA 409

Antibiotic and Concentration (ppm)

FIG. 2. Percent mortality of Littorina picta

larvae at one week intervals, throughout devel-
opment to metamorphosis, under different
antibiotic treatments. N=noantibiotic; С = Com-
bistrep (20 and 50 ppm); PG=Penicillin G (15
and 35 ppm); PX=polymixin (10 and 25 ppm).

kept constant under optimal conditions
with the exception that antibiotics were
added. The antibiotics used were Poly-
mixin B, Penicillin G and Combistrep
{containing streptomycin sulfate). The
antibiotics and concentrations selected
were based on results from preliminary
experiments. The effect on the mortalities
is shown in Fig. 2. A significant difference
between mortalities of larvae treated with
different antibiotics and concentrations
was obtained (PX 0:01). Polymixin gives
better survival than other antibiotics and
there is a significant interaction between
the antibiotic and concentration: a con-
centration of Polymixin at 25 ppm results
in significantly higher survival than at
10 ppm (P<0°01). There is also a
significant interaction between the week of
development, ard type and concentration
of antibiotic indicating that the effect of
treatment varies between weeks. Only
larvae treated with Polymixin B survived
to settlement after 3 weeks of development.

250 a No Antibiotic
>

od
5200 /
= if
y Y
п
> +4) Combistrep
5 Fat

150 A
‘oO _®
ic SS Cs
= Br
(=
о
+100
2 6 10 14 182822
Time (Days)

FIG. 3. Growth rate of Littorina picta larvae

reared with no antibiotic compared to growth
rate of larvae reared in water with 50 ppm
Combistrep applied continually throughout
develcpment. Each point represents the mean
maximum dimension of 10 larvae.

Penicillin G at 35 ppm decreased mortality
in the beginning, but all larvae died by
about day 16. Those larvae subjected to
no antibiotic or Combistrep suffered
highest mortality. The difference т
mortality between replicates of untreated
larvae (Fig. 2. N) after the Ist week was
p10bably due to faster growth of bacteria
and ligher rate of larval mortality in the
bowl where larvae first began to die.
By the end of the 2nd week. mortality was
approximately the same and very high in
both bowls.

Periodic dosage with antibiotics seems
preferable to continual treatment. The
optimal times for treating larvae are
immediately after hatching, at about |
week intervals, or at any time mortality
increased. When Combistrep (50 ppm) is
applied to larvae in this way, the mortality
is significantly decreased (to around 20%,
at time of settlement as opposed to 80-90%
untreated), and the growth rate is not
significantly decreased. Continual treat-
ment of larvae with Combistrep, as in the
above experiment, results in a significantly
decreased growth rate (Fig. 3). Of the

410 JEANNETTE W. STRUHSAKER AND JOHN D. COSTLOW, JR.

TABLE 2. Factorial analysis of variance. The effect of time and food treatment on mortality of larvae.

Three weeks <4 food treatments

4 replications. Only significant main effects and inter-

actions shown. Each treatment combination consists of 2 replicates (r) or 2 bowls of larvae

(65 larvae/bowl).

Source Ss Df
Week (w) 3,724 -93 2
Food (f) 3,093.89 3
Error (wf)* 704-45 6

Mean square F ratio Df Probability
1,862 -47 ISO 2 P< 0-01
1,031.29 8:8 136 P< 0:05

117-41

* Not a significant interaction between week and food treatment (wf) as tested by the week-food-repli-

cation (wfr) mean square.

3. antibiotics, Polymixin В is most suitable
for continuous treatment of larvae since
it not only significantly lowers the
mortality, but it also does not affect the
growth rate when used in the indicated
concentrations. Higher concentrations
of Polymixin B than those used above are
usually lethal.

Ultraviolet light was also used to
sterilize water in some experiments. For
any water contaminated with fungus. UV
light was the only treatment found
effective. Water was run slowly through a
unit containing ultraviolet light bulbs
(Loosanoff & Davis, 1963). Several pro-
blems were encountered, however. Water
had to be filtered carefully before running
through the UV unit because the ultravio-
let light often induced chemical changes
in suspended particles producing highly
toxic end-products. This was noticeable,
for example, when water was first treated
with Penicillin G. When this water was
subsequently treated with ultraviolet it
acquired a very acrid smell and was highly
toxic to larvae.

Experiments on the isolation, identifi-
cation and treatment of the pathogenic
bacteria inducing death of larvae are now
in progress. Preliminary results indicate
that the bacterium responsible for most
mortality is a yellow-pigment producing,
gram-negative motile bacillus. When
cultures of veligers are inoculated with

only small amounts of this bacterium,
the larvae die within 1 hour. When
pieces of the yellow material pro-
duced by the bacteria are taken in by
the larvae, they contract into the pro-
toconch and ciliary action ceases within
5 minutes.

According to Zobell (1946) most marine
bacteria (85%, or more) are gram-negative.
This may explain the higher effectiveness
of Polymixin B and Combistrep (with
streptomycin) in reducing mortality of
larvae since they are specific against gram-
negative bacteria. Penicillin G, on the
other hand, is specific against gram-
positive bacteria.

Food

Some experiments were conducted in
which larvae were fed different species of
unicellular algae, but none with varying
concentrations of algae. The initial
concentration used was approximately
270104 cells/larva (or 4:'0x10% cells/
ml sea water). This concentration was
frequently adjusted, however, depending
upon temperature, light conditions and
the number of larvae remaining alive.
The feeding rates of the larvae and the
length of time between water changes also
affects the concentration. Overfeeding
is usually toxic to larvae, for 2 possible
reasons: larvae are caught ard entangled
in clumps of algae and cannot feed

DEVELOPMENT OF LITTORINA 411

100

80 : 7
/ ig 3
oe 2

A EI
PE

50-1...

Percent Mortality

Food Treatment

FIG. 4. Percent mortality of Littorina picta
larvae at one week intervals, throughout
development to metamorphosis, under different
food treatments. NF=No food; IM—/sochrysis
+ Monochrysis; IMP=Isochrysis+-Monochrysis
+ Phaeodactylum; P = Phaeodactylum.

normally, and/or some toxic metabolite
is released by the algae in a lethal concen-
tration.

Three species of algae were fed to veli-
gers: the green flagellates Isochrysis
zalbana and Monochrysis lutheri, and a
diatom, Phaeodactylum tricornutum.
These were selected on the basis of their
suitability for feeding oyster and clam
larvae (Loosanoff & Davis, 1963) and
Nassarius larvae (Scheltema, 1962a).
Also, their isolation and culture have been
outlined previously in detail (Droop. 1954;
Guillard & Ryther, 1962; Levin, 1959;
Provasoli & Pitner, 1953).

The results of a factorial experiment
varying food type are summarized in
Table 2. Allfactors were kept constant at
optimal conditions except food, and no
antibiotics were used in food experiments
because they sometimes depress growth
rates. All larvae were collected from
intermediate parents. Preliminary results
indicated that neither /sochrysis galbana
nor Moncchrysis lutheri alone were suffi-

250 /- = Р

N
о
27
En
.
\

(U)

Length of Larvae
a
Оо
т

2 6 10 14 18 5212)" 7261430
Time (Days)

FIG. 5. Growth rate of Littorina picta larvae to
metamorphosis under different food treatments.
NF=No food; IM=Isochrysis+ Monochrysis;
IMP = Isochrysis-++ Monochrysis + Phaeodactylum;
P=Phaeodactylum. Each point represents the
mean maximum dimension of 10 larvae.

cient to sustain growth of Littorina picta.
Phaeodactylum tricornutum, however, gave
good growth and survival. For this
reason, the algae were tested in combi-
nations only, as shown in Fig. 4 and 5.

Table 2 shows that there is a significant
difference between the mortalities of
larvae given different foods (P< 0:05).

Those fed Phaeodactylum tricornutum
either alone or in combination (as shown
in Fig. 4 and 5) survived significantly
better than those given the combination of
Isochrysis galbana and Monochrysis lutheri
and those given no food at all. Only
larvae fed some Phaeodactylum tricornutum
survived to metamorphosis.

The absolute growth rates of larvae
fed the different foods are shown in Fig. 5.
Those fed Phaeodactylum tricornutum
alone grew fastest, followed by those fed
1/3 Р. tricornutum. The slight growth
of those fed /sochrysis galbana plus
Monochrysis lutheri and those given no
food is probably due to contamination
with a few cells of P. tricernutum from
pipettes used in changing larvae.

On the basis of these data and because
Phaeodactvlum tricornutum is easiest to

412 JEANNETTE W. STRUHSAKER AND JOHN D. COSTLOW, JR.

TABLE 3. Factorial analysis of variance. The effect of time, shell sculpture, salinity, and temperature

on mortality of larvae. Three weeks

<2 sculpture types <3 salinities X 3 temperatures x 2

replications. Only significant main effects and interactions shown. Each treatment combi-
nation consists of 2 replicates (г) or 2 bowls of larvae (65 larvae/bowl).

Source Sum of square Df Mean square F ratio Df Probability
Weeks (w) 6,3916-94 2 31,958 -47 192-02 2.8 P< 0:01
Temperature (t) 20333217 2 10,166 59 61:08 7238 P< 0:01
Salinity ($) 6,751:65 2 22375088 20:28 2,8 P< 0-01
Week-Sculpture (wp) 1,517-34 2 758-67 4-56 28 P< 0:05
Week-Temp. (wt) 3,672: 74 4 918-18 5:52. 7428 P< 0:05
Sculpture-Temp. (pt) 1,809 -25 2 904-62 5-44 2,8 P< 0:05
Error (Wtspr) 1,331-48 8 166-44

culture, this diatom seems the best larval
food at present. Experiments using
similar species of unicellular algae occur-
ring in Hawaii must still be performed.
Preliminary results indicate that larvae
grow slightly faster (with about the same
survival) in cultures in which Р. tricor-
nutum is supplemented with some local
unidentified nannoplankton (10-20
microns).

Temperature and Salinity

Several experiments on the effect of
various salinities and temperatures on
larval development were conducted. In
the experiment described here, the growth
and mortality of larvae from 2 extreme
sculpture populations (heavily sculptured
vs. smooth; see Introduction, and Struh-
saker, 1968 for dirferences between shell
types) were contrasted under 9 different
combinations of temperature and salinity,
with 2 replications per combination. A
factorial analysis was performed and the
percent mortalities under different treat-
ment combinations assessed. This
analysis is presented in Table 3. The
percent mortalities are shown in Fig. 6
and the growth rates in Figs. 7 and 8.

The results are summarized as follows:

1. The larval shells resemble those of
adults in parental populations (Struh-

saker, 1968).

2. There is а significant interaction
between time (week) of development and
sculpture (P< 0:05); with time, the morta-
lity of smooth larvae increases more
rapidly than the mortality of sculptured
larvae.

3. There is а significant interaction
between time (week) and temperature,
(P< 0:05): with time, the mortality at
different temperatures varies, the morta-
lity being higher at higher temperatures,
lower at lower temperatures and becoming
proportionately greater each week.

4. There is a significant difference in
mortality between salinities (P< 0:01). The
mortality rate at mean salinity (35 0/00)
is significantly lower than at extreme
salinities (25 0/00 or 45 0/00). There is an
indication that sculptured forms survive
better than smooth forms at higher
salinity, particularly at a higher tempera-
ture.

The variations in mortality between
extreme sculpture types appear to be
associated with the supratidal environment
in which each is found (Struhsaker, 1968).
The smooth form, in areas with greater
water renewal and cooler temperatures, 1s
more tolerant to low temperature, less
tolerant to high temperature, and high
salinity.

DEVELOPMENT OF LITTORINA 413

SMOOTH LARVAE

Percent Mortality

= metamorphosıs
ee I
= eS. A ac no
o 150 И metamorphosis
a 100 7
a
5 - 35 ppt
f=
2
S 220
4 +

200

no
O Metamorpnosi
+
150 Y
y

4 8 12 16 207722
Tıme (Days)

SCULPTURED LARVAE

GA: |

GA
“Bol
E 1
(Bs

200 OE
wi e 25 °C
150 Fa o 20 °C
100
45 ppt
À 1 1S eS SE] A AA
250 С metamorphosis
ЕЙ
Ze = г no
= 150 O anes
ñ
> +
5 100 35ppt.
5 И Е y MAA A EA
<<
Ben > 4
9 Е >
— 150 zn
100 Ÿ
2 5 ppt
1 Е et TEE ee 1 1 1
4 8 12316. 720024
Time (Days)

FIG. 6. Percent mortality of Littorina picta larvae (smooth and sculptured populations), at one week
intervals throughout development; different combinations of salinity—temperature.

FIG. 7. Growth rate of Littorina picta sculptured larvae under different salinity-temperature combina-

tions.

Each point represents themean maximum dimension of 10 larvae.

FIG. 8. Growth rate of Littorina picta smooth larvae under different salinity-temperature combina-
tions, Each point represents the mean maximum dimension of 10 larvae, i

414 JEANNETTE W. STRUHSAKER AND JOHN D. COSTLOW, JR.

Data are insufficient Гог significant
regression analyses and prediction of
optimal salinity-temperature combinations
(as, in) -Costlow,= et. а 1900. - 1962):
However, the information available shows
that the optimal salinity range is approxi-
mately 35 о/оо to 40 о/оо. Larval mortali-
ties increase sharply either below or above
that range in both sculpture types. As
development proceeds, larvae appear more
tolerant of salinity variation.

The optimal temperature range is from
approximately 24°C to 28°C. Below 24°C,
larval survival may be high (probably in
part because of decreased bacterial
growth), but the growth rate is consider-
ably slowed because larvae do not swim
or feed normally. Above 28°C, larvae
grow normally or slower than normal
(bacterial contamination may _ suppress
the growth of larvae) and the mortality is
high. Because of the possible effect of
bacterial contamination, the isolated effect
of temperature on larval growth and
mortality is difficult to interpret.

The absolute growth curves of larvae
are shown in Figs. 7 and 8; sculpture forms
of Litterina victa are shown in Fig 7,
smooth forms in Fig. 8. The growth rates
of the sculptured forms are, in general,
highest. The depression of growth at
higher and lower salinities and higher and
lower temperatures can be seen in both
sculpture types.

In a few preliminary experiments, it was
found that when larvae were removed
(after 1 week’s exposure) from high and
low salinities (25 ppt and 45 ppt) and high
and low temperatures 20C° and 30°C),
they were able to recover and survive to
metamorphosis when placed in a salinity
of 35:ppt at 25°C.

Substrate

Only a few experiments were performed
to test various substrates. Larvae were
usually placed in bowls containing attach-
ed pieces of rock from the natural substrate

about | week prior to the time metamor-
phosis usually occurs (3-4 weeks; 3-4
whorls). Four pieces of rock, approxi-
mately 1-5 cm? were attached to the
bottom of the bowls with aquarium
cement. The rocks used were palagonite
tuff, reef Jimestone, basalt and white
quartz. Quartz does rot occur in the
natural environment, but was included for
color contrast. Some larvae’ meta-
morphosed on all the rocks, but others
also attached on the bottom of the glass
bowl. Settlement appeared to depend
more on the presence of an algal film on
the bottom of the bowl and the rocks.
The post-veligers were obviously feeding
on this film. Removing portions of the
film from the surface resulted in snails
accumulating only in areas where algae
were still present. After snails are older,
however, they tend to aggregate in holes
on the surface of the rocks, moving out
over the surface of the glass bowl only
at night when feeding activity is greater.

If appropriate food is not present on the
substrate, larvae will continue to swim and
feed on Phaeodactvlum tricornutum for as
long as 5-6 weeks and until their shells have
attained the juvenile number of whorls
(5-6). After approximately 3 weeks, the
larvae metamorphose at any time if there
is suitable algae or detritus on the surface
of the bowl.

DISCUSSION AND CONCLUSIONS

Thorson (1950) discusses the factors
affecting the mortality of marine larvae.
Food, salinitv, temperature, currents,
predation, and availability of substratum
are the major environmental factors
suggested as being significant. Most
estimates of mortality in planktotro-
phic larvae are extremely high (about
99°). Thorson believes the greatest
mortality is probably due to predation.

Several environmental factors will signi-
ficantly affect the survival and growth of

DEVELOPMENT OE “EETTO RINA 415

Littorina picta larvae in laboratory
cultures. All of these may not be signi-
ficant in the mortality of larvae in the
natural environment because of new
factors introduced by culture conditions
and also because the larvae are able to
survive within the extremes encountered
in the open sea. Survival of larvae in
the laboratory may be less than in the
natural environment. The maximum
survival of larvae in laboratory cultures
up until time of settling was approximately
50%; through metamorphosis survival
was about 10%. The mean survival
through metamorphosis, however, was
only about 1%. It is likely that larval
survival in the field will approximate this,
but the periods of greatest mortality may
differ and originate from different factors
(Struhsaker, 1969).

In general, the requirements of the
larvae of Hawaiian Littorina picta are
specific, although the larvae are highly
flexible with respect to their tolerance to
certain factors (1.е. salinity, temperature).
They do not develop normally when
overcrowded, without the appropriate
type and amount of food, outside of a
certain salinity-temperature range, or in
water with heavy bacterial or fungal
contaminations. Many of the results
reflect the requirements of larvae in the
natural environment, but others, such as
overcrowding and disease, may be appli-
cable only to the laboratory environment.
The difficulty in rearing the larvae suggests
that their requirements are specific during
the planktotrophic stage. Also, the
physical marine environment of Hawaii is

relatively stable and a wide range of

tolerances would not be expected in the
marine larvae.

Bacterial contaminations may be critical
factors in the mortality of larvae only in
laboratory conditions. How important
this factor is in the mortality of marine
larvae in the natural environment is still
uncertain, Marine bacteria and fungi

tend to accumulate on egg capsules and
larval shells. In some fish eggs, for example,
the bacteria reduce the buoyancy of the
eggs, causing them to sink (Oppenheimer,
1955). The concentration of bacteria т
the sea water, however, is relatively small
(Zobell, 1946), and thus may not be a
significant factor in the mortality of eggs
or larvae in most instances.

Similarly, abnormal larvae are produced
in the laboratory by overcrowding and
antibiotics, which are not important
factors in the natural environment. The
variation in appearance and viability of
the larvae may not be affected entirely
by environmental factors, however; some
abnormalities may result from incomplete
and incompatible genetic combinations.
Loosanoff & Davis (1963) believe that
this is rare in clam and oyster larvae and
that most of the abnormalities they
encounter in cultures are due to lack of
food, overcrowding, etc. The types of
abnormal larvae which they describe are
similar to those of Littornia picta, as for
example, the incomplete shell develop-
ment.

Guillard (1959) also found that bacterial
toxins would kill oyster larvae or retard
their growth. Не stated that high
temperatures favor growth ‘of bacteria
and sometimes inhibit growth of larvae.
Гоозапсй & Davis (1963) determined that
Combistrep (50 ppm) inhibited growth of
bacteria and reduced mortality, but at
certain concentrations it also inhibited
growth of larvae. These results are
consistent with experiments with Littorina
picta.

Scheltema (1962a) used Phaeodactylum
tricernutum successfully to feed Nassarius
larvae. D’Asaro (1965) used natural
phytoplankton supplemented with Platy-
monas to feed Strombus gigas larvae.
Most workers agree that food is a critical
factor in successfully rearing larvae
through metamorphosis. However, Lit-
fornia picta larvae have the ability to live

416 JEANNETTE У. STRUHSAKER AND JOHN D. COSTLOW, JR.

without food for several days after
hatching, and it seems doubtful that
in the natural plankton they would
starve, although they may grow more
slowly.

Salinity and temperature also affect
growth and mortality of larvae in labora-
tory cultures. Costlow, Bookhout &
Monroe (1960, 1962) found that the
optimal salinity ranges for development
differed among different larval stages of
some crabs, and that salinity was the chief
limiting factor in the distribution of these
larvae. Unlike Littorina picta larvae.
they are subject to a wide range of salinity
associated with their migration from
Oceanic waters into estuaries. Г. picta
larvae do not encounter a wide range
of salinities until they reach the supratidal
region, at which time salinity may be an
important mortality factor in the larvae
and post-veligers. The temperature range
of L. picta larvae is also much narrower
than crabs, which may be a major factor
limiting this endemic species to the
Hawaiian Islands. The effect of tem-
perature is difficult to separate from effect
of bacteria; the latter may alter the growth
and mortality of larvae in experiments
without antibiotics.

Scheltema (1965) found a lower and
wider range of salinity tolerance т
Nassarius larvae (>15 ppt-17 ppt), at
least at the lower range, than occurs in
Littorina picta ( >30 ppt). Littorina picta
larvae will survive in salinities as low as
20 ppt, but they do not metamorphose
and they eventually die.

As with salinity, Nassarius obsoletus
larvae have a lower and a wider tempera-
ture tolerance range than Littorina picia
larvae (Scheltema, 1967). In М. obsoletus,
larvae completed developmert at 16-17°C
while L. picta larvae did not complete
normal development at 20°C. The lower
limit (approximately 23°C) for normal
development of L. picta is in accordance
with the narrow environmental tempera-

ture range occurring in the Hawaiian
Islands.

Similar to Nassarius, Littorina picta
has sume flexibility when replaced in
optimal conditions after a period of
exposure to extreme salinities or tempera-
tures. Further, £. picta can also delay
metamorphosis for some time (up to at
least 8 weeks) when по appropriate
substratum is provided.

At present, little is known of predation
on larval Littorina. The laboratory results
and field experiments done with other
mortality factors. indicate that predation
on settling larvae 15 only a minor mortality
factor for this species. The most impor-
tant factors affecting mortality of L.picta
are the extremes of salinity, oxygen,
temperature, wave action and oxygen
which settling larvae and post-veligers
encounter at time of settlement in the
supratidal region (Struhsaker, 1968).

ACKNOWLEDGMENTS

This research was supported by NSF Grant
GB-3270 awarded to Dr. John D. Costlow, Jr.
We would like to thank Dr. C. G. Bookhout and
the staff of Duke Marine Laboratory and Prof.
Vernon E. Brock, Dr. Philip Helfrich and parti-
cularly Dr. Garth I. Murphy, Hawaii Institute of
Marine Biology, for their assistance and for
facilities provided. We are also grateful to
Dr. R. R. L. Guillard, Woods Hole Oceano-
graphic Institution for algal cultures.

LITERATURE CITED

CONKLIN, E. G., 1897, The embryology of
Crepidula. J. Morph., 13: 1-226.

COSTLOW, J. D., JR., BOOKHOUT, С. С. &
MONROE, R., 1960, The effect of salinity and
temperature on larval development of Sesarma
cinereum (Bosc) reared in the laboratory. Biol.
Bull., 118: 183-202.

COSTLOW, J. D., JR., BOOKHOUT, C. G., &
MONROE, R., 1962, Salinity-temperature
effects on the larval development of the crab,
Panopeus herbstii Milne-Edwards, reared in the
laboratory. Physiol. Zool., 35: 79-93.

D’ASARO, C., 1965, Organogenesis, develop-
ment and metamorphosis in the Queen Conch,

DEVELOPMENT

Strombus gigas, with notes on breeding habits.
Bull. mar. Sci., 15: 359-416.

DROOP, M. R., 1954, A note on the isolation of
small marine algae and flagellates for pure
culture. J. Mar. biol. Assn. U.K., 33: 511-541.

FRETTER, V. & MONTGOMERY, M. C.
1968, The treatment of food by prosobranch
veligers. J. Mar. biol. Assn. U.K., 48: 499-519.

GUILLARD, R. R. L., 1959, Further evidence of
the destruction of bivalve larvae by bacteria.
Biol. Bull., 117: 358—266.

GUILLARD, В. КБ. L. & RYTHER, J. H., 1962,
Studies of marine planktonic diatoms. 1.
Cyclotella папа Husted and Detonula con-
fervacea (Cleve) Gran. Can. J. Microbiol., $:
229-239.

LEWIN, R. A., 1959, The isolation of algae. Rev.
Algol., 3: 181-197.

LOOSANOFF, У. & DAVIS, H. C., 1963, Rear-
ing of Bivalve Mollusks. /n: Advances т
Marine Biology, Vol. 1, Academic Press, N.Y.
136 p.

OPPENHEIMER, C. H., 1955, The effect of
marine bacteria on the development and hatch-
ing of pelagic fish eggs, and the control of such
bacteria by antibiotics. Copeia, 1: 43-49,

PAULSON, Т. С. & SCHELTEMA, К. S., 1968,
Selective feeding on algal cells by the veliger
larvae of Nassarius obsoletus (Gastropoda:
Prosobranchia). Biol. Bull.. 134: 481-489.

PROVASOLI, L., PINTNER, I. J., 1953, Eco-
logical implications of im vitro nutritional
requirements of algal flagellates. Ann. N. Y.
Acad. Sci., 56: 839-851.

SCHELTEMA, БК. S., 1961, Metamorphosis of
the veliger larvae of Nassarius obsoletus (Gas-
tropoda) in response to bottom sediment.
Biol. Bull., 120: 92-109.

SCHELTEMA, R. S., 1962a, Pelagic larvae of
New England intertidal gastropods. I. Nas-

OF LITTORINA 417

затих obsoletus Say and Nassarius vibex Say.
Trans. Amer. microsc. Soc., 81: 1-11.

SCHELTEMA, R. S., 1962b, Environmental fac-
tors affecting the length of pelagic development
in the gastropod, Nassarius obsoletus. Amer.
Zoologist, 2: 445.

SCHELTEMA, R. S., 1965, The relationship ot
salinity to larval survival and development in
Nassarius obsoletus (Gastropoda). Biol. Bull.,
129: 340-354,

SCHELTEMA, R. S., 1967, The relationship of
temperature to the larval development of Nas-
sarius obsoletus (Gastropoda). Biol. Bull.,
132: 253-265.

STRUHSAKER, J. W., 1966, Breeding, spawn-
ing, spawning periodicity and early develop-
ment in the Hawaiian Littorina: L. pintado
(Wood), L. picta Philippi and L. scabra (Lin-
naeus): - Proc: Malade | 50е. “Lond: 37:
137-166.

STRUHSAKER, J. W., 1968, Selection mechan-
isms associated with intraspecific shell variation
in Littorina picta (Prosobranchia: Mesogastro-
poda). Evolution, 22: 459-480,

STRUHSAKER, J. W., 1969, Population ecology
of the Hawaiian Littorina. (In prep.).

STRUHSAKER, J. W. & COSTLOW, J. D.,
JR., 1968, Larval development of Littorina
picta Philippi (Prosobranchia : Mesogastro-
poda), reared in the laboratory. Proc. malac.
Soc. Lond., 38 153-160.

THORSON, G., 1950, Reproductive and larval
ecology of marine bottom invertebrates. Biol.
Rev., 25: 1--45.

WALNE, P. R., 1964, The culture of marine
bivalve larvae. In: Physiology of Mollusca,
р 197-210, Vol. I. Ed., К. М. Wilbur & С. М.
Yonge. Academic Press, N.Y.

ZOBELL, C., 1946, Marine microbiology. Chro-
nica Botanica Co., Waltham, Mass. 240 p.

RESUME

QUELQUES EFFETS D’ENVIRONNEMENT SUR LE DEVELOPPAMENT
LARVAIRE DE LITTORINA PICTA (MESOGASTROPODA), ELEVE
EN LABORATOIRE

J. W. Struhsaker et J. D. Costlow

Les données suivantes proviennent d'une étude sur l'écologie des populations et sur
la variation intraspécifique du test de Littorina picta, de Hawai. Les larves d'individus
provenant de populations appartenant aux 2 types extrêmes de sculpture du test et au
type intermédiaire, ont été élevées dans les conditions constantes du laboratoire. Leur
mortalité, leur croissance et leurs différences dans la morphologie du test ont été évaluées.
Ces differences doivent rendre compte de la variation génotypique.

418

JEANNETTE W. STRUHSAKER AND: JOHN D: COSTLOW, JR:

Les conditions du laboratoire pour l’elevage des larves sont decrites et plusieurs
expériences, qui ont conduit à déterminer ces conditions, sont discutées. Les principaux
facteurs externes étudiés ont les effets des antibiotiques, de la nourriture, de la salinité,
de la temperature et du substrat sur la mortalité et la croissance des larves. En gézéral,
les conditions d’élevage pour tous les types de sculpture sont similaires. La meilleure
croissance et la plus faible mortalité sont obtenues quand les larves sont nourries avec
Phaeodactylum tricornutum et élevées dans de l’eau de mer dont la salinité est entre
35-40%, la température entre 24-25xC et qui a été traitee par 20-25 ppm de sulfate de
Polymixine B. La mortalité des larves élevées en laboratoire a genéralement été trés
eleves. Le maximum de survivants obtenus jusqu’a la fixation a été d’environ 50%;
et apres métamorphose de 10%. La moyenne de survivants aprés la métamorphose,
seulement d’environ 1%. Ainsi donc, les conditions de laboratoire ne doivent pas
fournir les conditions optimales d’environnement pour les larves.

Il y a eu des variations dans la croissance et la mortalité des différents types de sculpture
du test pour les extrémes de température-salinité. Celles-ci sont en corrélation avec la
distribution des types de sculpture du test dans la nature. Les formes fortement
sculpté2s, qui se rencontrent sur les substrats désséchés ой l’action des vagues est faible,
ont des larves qui sont plus résistantes aux fortes salinités et moins résistantes aux basses
températures que les larves des formes а coquilles lisses, qui se rencontrent sur les sub-
strats humides ой la force horizontale des vagues est forte. Tous les types de larves se
fixent sur une surface recouverte d’un film d’algues. Un autre important stimulus de
fixation est probablement le fait d’enlever l’eau du recipient par intermittence, apres
approximativement 3 semaines de développement. Les facteurs d’environnement cités
ci-dessus, sont discutés en relation avec leur importance dans la mortalité des RUES et
des postveligeres dans l’environnement naturel.

ASE;

RESUMEN

EFECTOS AMBIENTALES SOBRE LA LARVA DE LITTORINA
PICTA (MESOGASTROPODA) CRIADA EN LABORATORIO

Struhsaker y Costlow

Los resultados descriptos forman parte de un estudio general de la ecología y variación
intraespecifica de Lirtorina picta de Hawaii. Bajo condiciones constantes se criaron en
el laboratorio larvas de dos tipos con diferencia extrema en escultura y otra con escultura
intermedia, para determinar sus diferencias en la morfología conchológica, desarrollo y
mortalidad. Se asume que esas diferencias representan variaciones genotípicas.

Se indican las condiciones en laboratorio y los experimentos conduncentes a la deter-
minación de esas condiciones. Los factores ambientales principales fueron el efecto de
antibióticos, alimento, salinidad, temperatura y substrato, sobre el desarrollo y mortalidad
de las larvas. En general, condiciones para todos los tipos de escultura son similares.
El mayor desarrollo y supervivencia se obtuvieron en larvas criadas en agua de mar con
una salinidad de 35/40 °/oo y temperaturas de 24/25°C, tratados con 20-25 ppm sulfato
de Polimixina B y alimentadas con Phaeodactylum tricornutum. La mortalidad fué en
general elevada y la supervivencia maxima aproximadamente de un 50%, y 10%, experi-
mentaron metamorfosis. EI término medio de supervivencia despues de metamorfosi-
fue, sin embargo, sólo de 10% más o menos. En consecuencia, las condiciones de
laboratorio no proveen el ambiente optimo para las larvas.

Hay variación en el desarrollo y mortalidad de diferentes tipos de escultura a salinidad
y temperaturas extremas, que se correlacionan con la distribución de los tipos esculturales
en el ambiente natural. Conchas con escultura fuerte aparecen en substrato seco de
bajo oleaje y tienen larvas que son más resistentes a alta salinidad y menos resistentes
a baja temperatura que las larvas de concha lisa las cuales viven en substratos siempre
húmedos de oleaje horizontal más fuerte, Todos los tipos de larvas se asentaron sobre

DEVELOPMENT OF LITTORINA 419

superficies cubiertas con pelicula de algas. Otro estímulo importante para el asenta-
miento es probablemente la remoción intermitente de agua del recipiente, después de
un periodo de desarrollo aproximado de 3 semanas. Los factores indicados se discuten
en relación a su importancia en la mortalidad de las larvas e individuos post-veligeros

en el ambiente natural.
IS IRRE

ABCTPAKT

НЕКОТОРЫЕ ВОЗДЕЙСТВИЯ ВНЕШНЕЙ СРЕДЫ HA ЛИЧИНОЧНОЕ
РАЗВИТИЕ LITTORINA PICTA (MESOGASTROPODA),
ВЫРАЩЕННЫХ В ЛАБОРАТОРИИ

Ж. В. ШТРУХЗАКЕР И ДЖ. A. КОСТЛОУ

Описываемые результаты получены при общем изучении популяционной эко-
логии и внутривидовой изменчивости раковины у гавайской Littorina раса. Ли-
чинки моллюсков из популяций двух крайних популяций по типу скульптуры
раковины и из промежуточной были выращены при постоянных лабораторных
условиях: наблюдались их различия в морфологии раковины, в росте и смер-
тности. Предполагается, что эти различия отражают генетическую изменчи-
BOCTb.

Описываются лабораторные условия для выращивания личинок и обсуждают-
ся некоторые эксперименты, приводящие к определению этих условий. Боль-
шинство изученных факторов внешней среды были: влияние антибиотиков, пи-
щи, солености, температуры и субстрата на рост личинок и их смертность.
В общем, условия выращивания для всех типов по скульптуре раковины были
одинаковы. Сымый большой рост и высокая выживаемость были получены, ког-
да личинки выращивались в морской воде при солености 35-40% и при темпе-
ратуре 24-25°C, обрабатывались 20-25 ppm Polymixim В-сульфатом, при корм-
лении Phaedactylum tricornutum. Смертность личинок, выращенных в лаборатории,
была в общем очень велика. Максимум личинок, доживших до оседания, был
приблизительно 50%, а до метаморфоза-10%. Средняя выживаемость от начала
до конца матаморфоза, однако, была лишь около 1%. Лабораторные условия,
таким образом, не могут обеспечить самые оптимальные условия для выжива-
ния личинок.

Имеются колебания роста и смертности у личинок с различным типом ску-
льптуры раковины при крайних значениях солености и температуры. Они ско-
реллированы с распространением моллюсков с различным типом ‘скульптуры
раковины в естественных условиях. Формы сильно скульптированной раковины
встречаются на более сухих субстратах; места со слабым влиянием волнения
имеют личинку, которая более устойчива к высокой солености и менее ус-
тойчива к низкой температуре, чем личинки Форм с гладкой раковиной, ко-
торые встречаются на влажном субстрате, подвергающемся сильным горизон-
тальным воздействиям волн. Все типы личинок оседают на субстрат, покры-
тый пленкой водорослей. Другим видным стимулом для оседания является
возможно перемежающаяся. смена воды в резервуаре после приблизительно 3-х
недель развития личинок.

Выше рассмотрены факторы внешней среды в соответствии с их значимо-
стью для отмирания личинок и в стадии пост-велигер в естественных усло-
BUAX.

MALACOLOGIA, 1969, 9(2): 000-000

THE FUNCTIONAL MORPHOLOGY OF THE FEEDING
APPARATUS OF SOME INDO-WEST-PACIFIC DORID
NUDIBRANCHS

David K. Young
Department of Zoology, University of Hawaii, Honolulu, Hawaii, U.S.A.'
and

Systematics-Ecology Program, Marine Biological Laboratory, Woods Hole,
Massachusetts, U.S.A.?

ABSTRACT

Forty-eight species of Indo-West-Pacific dorids (Nudibranchia, Doridacea) are grouped
into general feeding types, each with characteristic morphological adaptations of the
buccal apparatus associated with specialized feeding. The functional morphology of
the buccal apparatus of 4 feeding types is discussed: (1) rasping sponge-feeders, (2)
sucking sponge-feeders, (3) engulfing opisthobranch-feeders, and (4) boring polychaete-
feeders.

Extensive adaptive radiation among the dorids is especially evident in their various
foods and modes of feeding. Conspicuous morphological adaptations to food are shown
in the structure of the buccal apparatus. Members of each family group of dorids exhibit
similar structure of the buccal apparatus and similar feeding habits. Because the buccal
parts of dorids are used by taxonomists as major characters, it is not surprising that the
dorids are grouped into rather discrete feeding types which parallel the taxonomic groups.

The sponge feeders, which comprise 7/8 of the dorids studied, are represented by the
rasping sponge-feeding Dorididae and Hexabranchidae and by the sucking sponge-feeding
Dendrodorididae. The engulfing opisthobranch-feeders are represented by 5 species of
the Gymnodoridinae (family Polyceridae) and the boring polychaete-feeders by a single
species of the Vayssiereidae.

The buccal apparatus of the dorids has undergone adaptive evolution in association
with specialized feeding habits. Differences in feeding among the 4 types are explained
by differing structure (or loss) of radular teeth and modifications of musculature involved
in the operation of the buccal mass and the radula. Similarities are given between the
feeding mechanism of each feeding type and that found in other opisthobranch,
prosobranch and pulmonate gastropods.

INTRODUCTION

Cylichna and Hurst’s (1965) study

The only comprehensive accounts avail-
able on the functional morphology of the
feeding apparatus, commonly termed the
“* buccal apparatus, ” in an opisthobranch
mollusc are Lemche's (1956) work on

Philine, Scaphander, Acteon, Cylichna and
Retusa. These animals are members of
the order Cephalaspidea, presumably the
most primitive order in the subclass
Opisthobranchia. No complete account
of the morphology and operation of the

1 Contribution No. 341, Hawaii Institute of Marine Biology, Honolulu, Hawaii. Based on a doctoral
dissertation submitted to the Graduate School, University of Hawaii. Honolulu, Hawaii.

? Systematics-Ecology Program Contr. No. 139.
of South Florida, Tampa, Florida, U.S.A.

Present address: Department of Zoology, University

422 DAVID K. YOUNG

buccal apparatus in members of the order
Nudibranchia has yet been given.

Descriptions are available of the
anatomy, histology and functioning of the
digestive systems of 4 aeolids, Aeolidia
papillosa, Cratena glotensis, Eoliina alderidi
and Facelina drummondi (Graham. 1938),
and | dorid, Jorunna tomentosa (Millott,
1937), but the musculture and functioning
of the buccal apparatus are largely ignored.
Forrest (1953) describes the functioning of
the digestive system and the feeding habits
of 13 species of dorids from the British
Isles but gives only a general account of
the functioning of the buccal apparatus
possessed by 2 feeding types: the sponge-
eating dorids and the ascidian-and
bryozoan-eating dorids.

Studies undertaken in the British Isles
and the Netherlands on the food of
nudibranchs suggest that North Atlantic
dorids of the same family groups are
restricted to similar types of food: one
subfamily of the Polyceridae (Polycerinae)
to bryozoans; the Onchidorididae to
bryozoans and barnacles: the Goniodoridi-
dae (=Okeniidae) to ascidians: and the
Dorididae to sponges (reviewed by
Thompson, 1964). There are no com-
parable studies of dorids in the Indo-West-
Pacific faunal region. This region
contains not only more species of dorids
than the North Atlantic, but it also has an
almost entirely different species composi-
tion.

Four general feeding types are distin-
guished on the basis of morphological
study of the buccal apparatus of 48 species
of Indo-West-Pacific dorids, and on food
studies of 18 of these (Young, 1965).
These feeding types are: (1) rasping
sponge-feeders, (2) sucking sponge-feed-
ers, (3) engulfing opisthobranch-feeders,
and (4) boring polychaete-feeders.

The present study deals with the gross
morphology and the function of the buccal
apparatus of each of the 4 feeding types
represented by 48 species of Indo-West-

Pacific dorids. It is beyond the scope
of this paper to completely identify all
muscles of the buccal apparatus in any
One species and, as such, this account
differs from the comprehensive studies of
Cylichna by Lemche (1956) and of Philine
Бу Hurst (1965). Emphasis is given to
those components of the apparatus that
appear to be functionally important.

METHODS AND MATERIALS

Forty-three species were examined
from collections from Oahu and Kauai
in the Hawaiian Islands between 1962
and 1966 (Kay & Young, 1969). Four
additional species were collected from
Eniwetok Atoll during 1965 and one
further species was obtained from
Palmyra Atoll during 1962 (Young, 1967).

Collections were made primarily from
the intertidal zone to a depth of 5 meters.
and several were taken in depths up to
100 meters by dredging.

The dorids were relaxed by refri-
geration, fixed in 5% formalin and
preserved in 70%, ethyl alcohol.

Dissections were made under a
dissecting microscope using fine needles,
forceps and razors. The buccal apparatus
was stained with aqueous methylene blue.
The radular teeth and buccal armature
were permanently mounted with Euparal
on microscope slides.

Observations of feeding behaviour
made from dorids held in aquaria were
supplemented by observations in the
field and analyses of feces and stomach
contents. The results from these food
studies will be discussed by the author in
detail elsewhere.

RESULTS
I. Rasping sponge-feeders

|. Alimentary tract

In the rasping sponge-feeding dorids

FEEDING APPARATUS OF DORID 423

TABLE 1. Thirty-nine rasping sponge-feeding dorids studied here, and their taxonomic positions.

FAMILY DORIDIDAE

Subfamily Doridinae
Doriopsis granulosa Pease 1860
Doriopsis pecten (Collingwood 1881)
Doriopsis viridis Pease 1861
Doriorbis nucleola (Pease 1860)

Subfamily Archidoridinae
Archidoris hawaiiensis Kay & Young 1969
Archidoris nubilosa (Pease 1871)

Subfamily Platydoridinae
Platydoris formosa (Alder & Hancock 1866)
Platydoris sp.

Subfamily Discodoridinae
Discodoris fragilis (Alder & Hancock 1866)
Carminodoris grandiflora (Pease 1860)
Carminodoris nodulosa (Angas 1864)

Subfamily Halgerdinae
Halgerda rubra (Bergh 1905)
Halgerda graphica Basedow & Hedley 1905
Halgerda apiculata (Alder & Hancock 1866)

Subfamily Trippiinae
Trippa osseosa (Kelaart 1859)
Trippa echinata (Pease 1860)
Trippa scabriuscula (Pease 1860)

that were dissected (Table 1), the mouth is
ventral to the most anterior portion of the
mantle, anterior to the foot and between 2
ventrolateral oral tentacles. Posterior
to the mouth is a muscular buccal
apparatus which opens posterodorsally
into a greatly distensible esophagus (Figs.
1-4, es).

Among these 39 species of dorids,
salivary glands are absent only in Jorunna
tomentosa (Millot, 1937). In all others, a
pair of free-ending, elongate salivary
glands (Figs. 1-4, sg) enter at each side
of the esophageal junction with the
buccal mass and open into the lumen of
the buccal mass. The nerve ring encircles
the esophagus immediately posterior to
the buccal apparatus. A pair of buccal
ganglia (Figs. 2, 3, 5, 6, bg) lie ventral to
the esophagus at the buccal-esophageal
junction.

Subfamily Kentrodoridinae
Jorunna tomentosa (Cuvier 1804)
Asternotus cespitosus (van Hasselt 1824)
Subfamily Diaululinae
Thordisa hilaris Bergh 1905
Thordisa setosa (Pease 1860)
Peltodoris fellowsi Kay & Young 1969

Subfamily Chromodoridinae
Hypselodoris vibrata (Pease 1860)
Hypselodoris peasei (Bergh 1880)
Hypselodoris lineata (Eydoux & Sou!eyet 1852)
Hypselodoris kayae Young 1967
Hypselodoris tryoni (Garrett 1873)
Hypselodoris daniellae Kay & Young 1969
Chromodoris geometrica (Risbec 1928)
Chromodoris trimargirata (Winckworth 1946)
Chromodoris albopustulosa (Pease 1860)
Chromodoris imperialis (Pease 1860)
Chromodoris lilacina (Gould 1852)
Chromodoris decora (Pease 1860)
Chromodoris petechialis (Gould 1852)
Chromodoris voungbleuthi Kay & Young 1969

FAMILY HEXABRANCHIDAE
Hexabranchus marginatus (Quoy & Gaimard
1832)
Hexabranchus aureomarginatus Ostergaard 1955
Hexabranchus pulchellus (Pease 1860)

The esophagus extends posteriorly and
opens posteroventrally into a thinwalled
micgut (Figs. 1-4. mg). The midgut
opens into the digestive diverticula of the
massive digestive glard (dg). The caecum
(ca) appears as a blind sac on the left
side or to the rear of the midgut. The
intestine (in) runs forward from the
midgut, bends to the right (thereby
forming the characteristic ** dorid loop ”
of the Doridacea), and passes posteriorly
on the dorsolateral right surface of the
digestive gland to the anus. The anus
is in a median posterodorsal position and
is usually surrounded by secondary
branchiae.

2. Buccal Apparatus

Morphology The generalized buccal
apparatus of rasping sponge-feeding dorids
may be divided into 3 distinct regions: an

424 DAVID K. YOUNG

FIG. 1. Doriopsis granulosa. Lateral view of the alimentary tract (anterior at right).

FIG. 2. Chromodoris decora. Lateral view of the alimentary tract (anterior at right).

ac anterior constriction ebr extrinsic buccal retractor muscle

arp anterior radular protractor muscle ebr 1, 2 extrinsic buccal retractor muscles 1, 2

ato anterior transverse odontophoral muscu- eor 1-3 extrinsic Oral retractor muscles 1-3
lature erm esophageal retractor muscle

bb buccal bulb es esophagus

bg buccal ganglion ibr intrinsic buccal retractor muscles

bl buccal lip il inner lip

bm buccal mass ilb intrinsic longitudinal buccal musculature

bs buccal sheath in intestine

Бу buccal vestibule 10b intrinsic oblique buccal musculature

ca caecum J jaw

ct connective tissue lbr lateral buccal retractor muscles

dg digestive gland Ic lateral cartilage

FEEDING APPARATUS OF DORID 425

FIG. 3. Hexabranchus marginatus. Lateral view of the alimentary tract with the intrinsic buccal longi-
tudinal musculature cut away and with the extrinsic buccal retractor muscle, the extrinsic oral muscles
1-3 and the oral branches of the columellar muscle severed for illustrative purposes (anterior at right).

FIG. 4. Halgerda graphica. Lateral view of the alimentary tract (anterior at right).

anterior, an intermediate and a posterior
buccal region. These regions are visibly
separated by 3 constrictions of the buccal
wall, the “lips” (Alder & Hancock,
1855).

The anterior buccal region commence
at the outer lip (Figs. 5, 6, ol) at the
mouth, passes back through a plicated
oral tube (ot) and terminates posteriorly
at the inner lip (il). Both the outer and

mar marginal radular protractor muscle
mbr medial buccal retractor muscles
med medial radular retractor muscle

mg midgut

ocm oral branches of the columellar muscle
od odontophore

ol outer lip

ot oral tube

pe posterior constriction

pd duct of ptyaline gland

pg ptyaline gland

ph pharynx

poc posterior odontophoral compressor mus-
cle

pto posterior transverse odontophoral mus-
culature

ra radula

rm radular membrane

rs radular sac

rt radular teeth

sbm superficial buccal musculature

sg salivary glands

426

"num
“ron

Mm
MA,
trim

Y о Anny
2. 19 py, an
MAA)
ms AUDIO
Mon amen
np ОЗ
» MIMI
HET
MN MAA)

DAVID K. YOUNG

FIG. 5. Doriopsis granulosa. Right sagittal section of the buccal apparatus (anterior at right).

FIG. 6 Chromodoris decora. Right sagittal section of the buccal apparatus (anterior at right).

inner lips are ring-like thickenings of

connective tissue encircled by sphincter
muscles. The wall of the oral tube is
composed of loose connective tissue which
is interspersed with muscle fibers and
glands, as in Philine (Sterner, 1912:

Hurst, 1965). Longitudinal muscle fibers
extend along the length of the oral tube.
Oral branches of the columellar muscle
(Figs. 1-4, ocm) pass from insertions in the
oral tube at the level of the outer lip and
intermesh with the medial and lateral

FEEDING APPARATUS OF DORID 427

branches of the columellar muscle which
lie along the length of the body wall
enclosing the haemocoel. Three pairs
of muscles, the extrinsic oral retractor
muscles (Figs. 1-4, eor 1, 2, 3), insert
posteriorly in the oral tube and pass
posterolaterally to origins in the adjacent
body wall.

The intermediate buccal region lies
immediately posterior to the inner lip of
the oral tube. This region is similar to
that in pulmonates termed the “ buccal
vestibule ” (Figs. 5, 6, bv) by Amaudrut
(1898). The wall of the buccal vestibule is
thin, membranous and highly pliable.
The cuticular lining of the posterior
buccal region usually ends at the buccal
vestibule, but in the Hexabranchidae it
also lines the buccal vestibule. While few
intrinsic muscles are on this structure
itself, the wall of the buccal vestibule serves
as an area for attachment of longitudinal
musculature from the posterior buccal
region.

The heavily muscled, posterior buccal
region, or the “ buccal mass ” (Alder &
Hancock, 1855), is bounded anteriorly
by a broad, ring-like thickening of circular
musculature at the buccal lip (Fig. 5,
bl) and posteriorly by the esophageal
orifice. The buccal mass encloses the
ventrally positioned odontophore (Fig. 6,
od) which bears the radula (Figs. 5, 6, ra).

The lumen of the buccal mass is lined
with a thin cuticular layer (Fig. 7A). The
histology of this layer has been described
in Jorunna tomentosa by Millott (1937).
In some rasping sponge-feeders the cuti-
cular layer is thickened at the buccal lip
as a jaw. The jaw has a characteristic
shape appearing. for example, as a
horseshoe with the free ends directed
dorsally (Fig. 7B) or 2 plicated lateral
plates (Fig. 7C). Imbedded in the jaws
are densely set, singly hooked or bifid,
chitinous elements or buccal armature.

From the posteroventral portion of the
buccal mass, a rounded radular sac (Figs.

1-6, 8A, rs) protrudes between 2 lateral
thickenings. Passing obliquely in an
anteroventral direction from a postero-
medial origin dorsal to the radular sac
and ventral to the esophagus, a thin sheet
of superficial buccal musculature (Figs.
1-4, sbm) spreads over each lateral
thickening and inserts at a dorsoventral
furrow marking the anterior boundary of
the lateral thickening. The dorsoventral
furrow or posterior constriction (Fig.
3, pc) extends ventrally from the esopha-
geal junction with the buccal mass and
passes mid-ventrally into the buccal mass
immediately anterior to the radular sac.

When the layers of intrinsic buccal
musculature are removed, it is seen that
the lateral thickenings of the buccal mass
are protrusions of the superficial buccal
musculature caused by the underlying
odontophore. The odontophore 15
bounded оп each side Бу а thick layer of
musculature which passes posterodorsally
from lateral origins with the odontophcral
cartilages to insertions along the lateral
edge of the radular membrane (Fig. 8A,
rm) borne upon the odontophore.
Because of its presumed function, this
layer of musculature will be termed the
marginal radular protractor muscle (Fig.
8B, mar).

The radular membrane is composed of
2 directly opposable, elongate semicircles
of tissue upon which are borne regular
transverse rows of posteriorly recurved
radular teeth (Fig. 8A, rt). The halves of
the radular membrane are joined ventrally
and posteriorly so that the posterior
portion forms the pouch-like radular sac.
The dorsal portion of each half is stretched
laterally across the odontophore by the
marginal radular protractor muscle.

The rows of radular teeth in each half
of the radular membrane are positioned
so that an individual tooth in a given row
has its mirror image directly opposite in
the corresponding row of the opposite half
of the radular membrane. The teeth are

DAVID K. YOUNG

1.0mm

0.5mm

2.0mm

o
o
a

FEEDING APPARATUS OF DORID 429

all laterals with hook-shaped tips and
medial, wing-like projections or flanges.
The outer edges of the teeth are smooth,
denticulate or pectinate.

On both sides of the radula are ovoid,
laterally compressed masses of connective
tissue termed the odontophoral cartilages
or “lateral cartilages ” (Prashad, 1925)
(Figs. ЗВ, Ic; 9 A, В). These cartilages
are composed of large, vacuolated, con-
nective tissue cells which are reported to be
interspersed with muscle fibres and
deposits of calcium salts and glycogen in
cephalaspidean opisthobranchs (Gabe &
Prenant, 1952). The lateral cartilages
form the support of the radula and are
sites of origin for muscles that operate
the radula and odontophore.

A thin strip of muscle, which is here
termed the posterior odontophoral сот-
pressor muscle (Fig. 9B, рос). is attached to
the posteroventral and posterodorsal
edges of each lateral cartilage. With the
exception of the posterior odontophoral
compressor muscle, the surfaces of the
lateral cartilages are devoid of any
conspicuous intrinsic musculature.

The lateral cartilages are united antero-
dorsally by a thin strip of connective tissue
(Fig. 9AB, ct). Ventral to this connec-
tion, they are joined by transverse muscle
fibres, the anterior transverse odontophcral
muscles (Fig. 9A, ato). These muscles
are Overlaid by a pair of dorsoventrally
directed muscles, termed the “ anterior
radular protractor muscles ” in Cylichna
by Hurst (1965) (Fig. 8B, arp), connecting
the cuticular lining and the ventral portion
of the buccal wall to the anterior edge of

the radular membrane and forming the
anterior portion of the odontophore.
Posteroventrally the lateral cartilages are
connected by a muscle band, the posterior
transverse odontophoral muscle (Fig. 9B,
pto), forming the posterior portion of the
odontophore. The radula is thereby
encompassed laterally by the lateral
cartilages, anteriorly by the anterior
transverse odontophoral muscle and
posteriorly by the posterior transverse
cdontophoral muscle.

Paired muscles, which are tar to the
** medial radular retractor muscles ” in
Cylichna (= Musculus retractor radulae
medialis, Lemche, 1956), each connect the
ventrolateral portion of a lateral cartilage
to the dorsomedial-inner surface of the
radular membrane (Fig. 8B, med). The
radula thereby stands upright between the
paired medial radular retractor muscles
and the lateral cartilages.

Several layers of muscle fibres, the
intrinsic longitudinal buccal musculature
(Figs. 1-3, ilb), originate at the posterior
constriction on each side of the buccal
mass. The thicker outer layer of mus-
culature passes anteriorly to lateral inser-
tions in the posterior-most edge of the oral
tube, whereas the thinner inner layer has
insertions in the wall of the buccal
vestibule. In the Hexabranchidae, an
additional layer of musculature, the
intrinsic oblique buccal musculature (Fig. 3,
iob), passes obliquely in an anterodorsal
direction around each side of the buccal
mass from origins in the posterior cons-
triction and inserts mid-dorsally along the
buccal wall.

FIG. 7. A. Thordisa hilaris.

the lateral plate-like jaws.

Lateral view of the cuticular lining of the buccal mass. В. Hypselodoris
vibrata. Anterior view of the horseshoe-shaped jaw.

C. Hexabranchus marginatus. Anterior view of

FIG. 8. A. Lateral view of a radula of a rasping sponge-feeding dorid. B. Lateral view of a radula,
a lateral cartilage (area within dotted line), and radular musculature of a rasping sponge-feeding dorid.

FIG. 9. A. Anterior view of the lateral cartilages and odontophoral musculature of a rasping sponge-
feeding dorid. B. Posterior view of the lateral cartilages and odontophoral musculature of a rasping

sponge-feeding дома,

430 DAVID K. YOUNG

ebr eor3 ост

FIG. 10. Protraction of the odontophore in a
rasping sponge-feeding dorid (diagrammatic).
Arrows depict increase in blood pressure in the
cephalic haemocoel. A. Retracted position of
the odontophore. B. Opening of the outer and
inner lips and foreshortening of the buccal mass.
C. Opening of the buccal lip and protrusion of
the odontophore. D. Protracted position of the
odontophore; radula in position for the upward
and forward rasping stroke.

The posterior constriction is a common
area of muscle attachment and becuase of
the great amount of intertwining of
muscle fibres it is often difficult to ascer-
tain the exact connections of muscles
converging in this area. It is apparent,
however, that the superficial buccal mus-
culature forms insertions with the circular
muscles of the buccal wall and the
intrinsic logitudinal buccal musculature.

The only muscles connecting the buccal
mass to the body wall are the extrinsic
buccal retractor muscles (Figs. 1-3, ebr).

The paired extrinsic buccal retractor
muscles are undivided in the majority of
the rasping sponge-feeding dorids, but in
some dorids (e.g., Halgerda graphica; Fig.
4, ebr 1, 2) each muscle is divided distally
into 2 parts. These muscles have
insertions in the posterior constriction
of the buccal mass and _ ventrolateral
origins in the medial branches of the
columellar muscle. Muscle fibres from
the extrinsic buccal retractor muscles
insert along the ventrolateral anterior
edge of the lateral cartilages as well as in
the superficial and intrinsic buccal mus-
culature.

Function. Observations of rasping
sponge-feeding dorids in the process of
feeding indicate that the sequence of
events described by Millott (1937) in
Jourunna tomentosa may generally apply
throughout the entire group. These feed-
ing movements are summarized as follows:
(1) expansion of the outer and inner lips;
(2) exposure of the buccal lip; (3) expan-
sion of the buccal lip; (4) protrusion of
the odontophore through the parted lips;
(5) upward and forward movement of the
radula over the odontophore; (6) simul-
taneous retraction of the odontophore
and the radula: and (7) contraction of
the buccal lip.

Protrusion of the odontophore and
foreshortening of the buccal apparatus
(Fig. 10, A-D) is initiated by contraction
of the intrinsic longitudinal buccal mus-
culature. The absence of any extrinsic
buccal muscles that could act as
protractors suggests that increased blood
pressure in the cephalic haemocoel
probably plays an important role in the
protrusion process as shown in Philine
by Hurst (1965). Posterolateral support
of the odontophore is given by the superfi-
cial buccal musculature.

The buccal lip and the jaw (if present)
are expanded by relaxation of the circular
musculature of the buccal wall during the
protraction phase of the odontophore.

FEEDING APPARATUS OF DORID 431

The shape of the jaw is largely determined
by the state of contraction or relaxation
of the muscles of the buccal wall. The
jaw probably assists in directing the
odontophore as it passes in and out
between the buccal lip. The jaws in
those dorids having recurved buccal
armature may also function in grasping
portions of sponge which are then
rasped away by the radular teeth.

The odontophore is the complex, largely
self-contained unit of connective tissue,
cartilage and muscles that provides
support for the radula and aids its
operation. The operation of the radula
depends on the production of a firm
“bending plane (Ankel. 1937) and on
the stretching of the radular membrane
over it so that the functional teeth are
erected and exposed to the feeding surface.
The bending plane is produced by the
support given to the radular membrane by
underlying lateral cartilages which, in
turn, can be flexed posteriorly by con-
traction of the posterior odontophoral
contractor muscles. The hooked tip of
each radular tooth (aided by denticles, if
present) acts in rasping away small pieces
of sponge and the concave surface pro-
duced by the flange acts as a scoop in
conveying the particles to the esophagus.

As the odontophore is protruded
through the widespread buccal lip, the
radular membrane is pulled anteriorly and
laterally over the lateral cushions by
contraction of the anterior radular pro-
tractor muscles and the marginal radular
protractor muscles. The lateral pull of
the marginal radular protractor muscles
expands the radular membrane and ex-
poses and erects the functional radular
teeth. Contraction of the anterior
transverse odontophoral muscle and
relaxation of the posterior transverse
odontophoral muscle act in spreading the
lateral cartilages and increasing the area
of the radular rasping surface.

The upward and forward movement of

the radula occurs when the radular mem-
brane is brought up and over the tips of
the lateral cushions by the contraction of
the paired medial radular retractor
muscles. This movement, which
immediately follows relaxation of the
opposable protractor muscles (the margi-
nal radular protractor muscles and the
anterior radular protractor muscles), acts
in directing the erected teeth against the
feeding surface so that pieces of sponge are
rasped away.

Retraction of the odontophore into the
buccal mass is brought about by
contraction of the paired extrinsic buccal
retractor muscle. The oral tube is
retracted by contraction of the oral
branches of the columellar muscle and the
extrinsic Oral retractor muscles.

According to Millot (1937), when the
odontophore is completely retracted and
thrust into the esophageal opening, sponge
particles are taken up by the posteriorly
beating cilia which line the esophageal
lumen. Mucus secreted by the glandular
cells of the buccal apparatus and the
esophagus coats the sponge particles while
enzymes secreted by the salivary glands
initiate digestion (Forrest, 1953).

3. Discussion

Although a comprehensive functional
morphological study of the buccal
apparatus of rasping sponge-feeding
dorids is lacking in the literature, it 15
apparent from the terminology used by
early workers that generalized functions
of the more conspicuous external mus-
culature had been determined at an early
date. For example, in 1855 Alder &
Hancock-~used;;.the. "terms, ““retractof
muscles of the channel of the mouth, ”
“* retractor muscles of the buccal mass ”
and ‘protractor muscles ” respectively
for the ** extrinsic oral retractor muscles ”’,
‘** extrinsic buccal retractor muscles ” and
‘intrinsic longitudinal buccal mus-
culature, ”

432

TABLE 2.

DAVID K. YOUNG

Cylichna
(Lemche, 1956)

|
|

Philine
(Hurst, 1965)

Homologous buccal musculature of Cylichna, Philine and the rasping sponge-feeding dorids.

|
Dorids
(Young, present study)

. pharyngis posterior

. retractor radulae medialis

Sa Sie ae

. retractor radulae marginalis

. constrictor pharyngis anterior

Sphincter muscles
Superficial buccal musculature

Radular occlusor muscles

| Circular musculature at buccal lip
Superficial buccal musculature
Medial radular retractor muscles

Marginal

M. rotellae dorsoventralis

? M. rotellae circularis

M. columellaris dorsolateralis
lateralis ventrolateralis

Outer oblique muscles

Anterior transverse muscle
|

Posterior transverse muscle

Outer branch of columellar

muscle Inner branch of

radular protractor
muscles

| Anterior radular protractor
muscles

Anterior transverse odontophoral
muscle

| Posterior transverse odontophoral
muscle
|
Oral branches of the columellar
muscle

columellar muscle

М. pharyngis longitudinalis
ventralis

M. retractor pharyngis
|

The musculature of the buccal apparatus
of rasping sponge-feeding dorids exhibits
few obvious homologies (Table 2) to that
described in Cylichna (Lemche, 1956) and
Philine (Hurst, 1965). Homologies are
masked, in part, because of their radically
different modes of feeding. The radula
of these cephalaspidean opisthobranchs
has a “ grabbing ” function (Hurst, 1965),
Whereas the radula of rasping sponge-
feeding dorids has a rasping action.

Among the prosobranch gastropods,
several members of the Fissurellidae graze
upon sponges (Morton, 1958), but their
mode of feeding is distinctly different from
the feeding of rasping sponge-feeding
dorids. The Fissurellidae have rhipidog-
lossan radulae. The function of this

Ventral tensor muscles

| Extrinsic muscle pairs IV and У

Intrinsic longitudinal buccal mus-
culature

Extrinsic buccal retractor muscles

type of radula involves a complex inter-
action of buccal muscles with 2 pairs of
cartilages producing a sweeping or brush-
ing action of the radula (Fretter &
Graham, 1962).

The prosobranch gastropods possessing
taenioglossan radulae have a_ feeding
mechanism basically similar to that of the
rasping sponge-feeding dorids. Although
the food, radular teeth and buccal mus-
culature are dissimilar, the operation of the
radula of Viviparus (which feeds on algae),
as described by Eigenbrodt (1941),
resembles that of these dorids. In both,
the radular membrane spreads and passes
over the bending plane produced by a
single pair of supporting cartilages and
the teeth are erected against the feeding

FEEDING APPARATUS OF DORID 433

lor

eee MI,

МЕРЕ SEE RARES ¿Ny

pe ee RCE

FIG. Il. Dendrodoris nigra. Right sagittal section of the anterior portion of the buccal apparatus

(anterior at right).

FIG. 12. Dendrodoris nigra. Lateral view of the alimentary tract with the extrinsic muscles of the buccal
apparatus severed for illustrative purposes (anterior at right),

434 DAVID К.

surface. When the radular membrane is
retracted, the recurved radular teeth rasp
against the food and tear away pieces
which are then passed back into the
esophagus.

Il. Sucking sponge feeders
1. Alimentary tract

The sucking sponge-feeding dorids,
represented in this study by Dendrodoris
nigra (Stimpson, 1855), D. tuberculosa
(Quoy & Gaimard, 1832) and Dendrodaris
coronata Kay & Young, 1969 of the
family Dendrodorididae, have a mouth
that is situated anterior to the foot,
ventral to the anterior
the mantle and between 2 small oral
tentacles; "Ihe oral Бе (Fig? 11: ot)
with a triangular shaped bore extends
posteriorly from the mouth, through the
muscular buccal bulb (bb) and into the
elongate, coiled pharynx (Figs. 11, 12, ph).

A large bilobed gland, the “ ptyaline
gland ” (Bergh, 1884) (Fig. 12, pg),
lies underneath the buccal bulb and gives
rise to a duct (Figs. 11, 12, pd) which enters
the posteroventral portion of the buccal
bulb immediately ventral to the oral tube.
The duct extends along the entire length
of the buccal bulb and opens ventrally at
the mouth opening.

Two small salivary glands are located
at the junction of the pharynx with the
esophagus, as described and figured by
Eliot (1906, Pl. 57, figs. 4.7) in Doridopsis
(=Dendrodoris) nigra, and 2 buccal
ganglia each have a connective leading
anteriorly to the nerve ring immediately
posterior to the buccal bulb.

The esophagus (Fig. 12, es), which is
enclosed by a large digestive gland (dg),
extends posteriorly from the pharynx into
an extremely thin-walled midgut (mg).
The midgut is so perforated by digestive
diverticulae of the digestive gland that its
shape cannot be determined by gross
dissection. The intestine (in) emerges

portion of

YOUNG

from the posterior portion of the midgut
and extends posteriorly to а terminal,
mid-dorsal anus. There is no indication
of the so-called “ dorid loop” in the
intestine.

2. Buccal apparatus

Morphology. The buccal apparatus of
the dendrodorids is quite unlike any others
in the Doridacea. The structure is so
highly modified in association with specia-
lized feeding that the odontophore and
radula are absent. It is reasonable to
suppose, as suggested by Hancock (1865)
and Eliot (1906), that the buccal ganglia
and salivary glands mark the commence-
ment of the esophagus and the termination
of that portion of the alimentary tract
homologous with the buccal apparatus of
other dorids.

The anterior portion of the buccal
apparatus 15 partially enclosed by a sheath
of connective tissue, termed the “ buccal
sheath ” (Fig. 11, bs) by Hancock (1865).
The buccal sheath is open anteriorly to
the exterior and connected posteriorly to
an underlying mass of intrinsic muscula-
ture, the buccal bulb. The buccal bulb is
largely comprised of longitudinal and
transverse muscle fibres as shown by
Hancock (1865). The triangular lumen
of the oral tube is lined with cuticle from
which bundles of radial muscles radiate
out to circular musculature surrounding
the tube similar to that described by
Brown (1934) in the oral tube of Philine
and by Maas (1965) in the first buccal
pump of some pyramidellids.

Oral branches of the columellar muscle
(Figs. 11, 12, ocm) insert in the ventro-
lateral anterior portion of the sheath and
extend posteriorly to the medial branches
of the columellar muscle along the foot.
Several pairs of muscles, which will be
termed the extrinsic lateral buccal retractor
muscles (г), insert posterolaterally in
the buccal bulb and pass laterally to
origins in the adjacent body wall. The

FEEDING APPARATUS OF DORID 435

number of extrinsic lateral buccal retractor
muscles varies within and between species
(e.g., 3-4 pairs in Dendrodoris nigra).
A pair of broad muscles, the extrinsic
medial buccal retractor muscles (mbr).
originate posteriorly in the columellar
muscle of the foot, pass anteriorly and
insert along each side of the oral tube and
the surrounding circular musculature of
the buccal bulb.

Function. The tood of the dendrodorids
has long been a source of speculation but
the only account verified by both field
observations and gut examinations is that
of Ghiselin (1964) who reports that
Doriopsilla albopunctata feeds on “а
variety of sponges.” Food studies
demonstrate that Dendrodoris nigra feeds
on the sponge Halichondria dura in Hawaii.
Several specimens of D. nigra held in
aquaria were Observed during the process
of feeding to each thrust an everted
proboscis through an osculum of H. dura.
Spicules of H. dura were recovered from
the feces and alimentary tracts of
specimens of D. nigra collected from the
field.

Protraction of the buccal bulb (Fig. 13,
A-C) is brought about by increased blood
pressure in the cephalic haemocoel as
suggested by Hancock (1865). An
absence of any muscles that could act as
protractors precludes protration of the
buccal bulb by muscular action. Feeding
occurs while the buccal bulb is in the
protracted position.

The term “ suctorial ” was used to
describe the buccal apparatus of the
dendrodorids by Alder & Hancock (1866),
and although later workers retain this
function of the buccal apparatus as
descriptive for the group, no attempt has
been made to describe the way in which
the supposed suction is achieved. It is
possible that closure of the triangular
lumen of the oral tube in the dendrodorids,
as in the Ist buccal pump of the pyramidel-
lids (Maas, 1965), is produced by the

FIG. 13. Protraction of the buccal bulb in a
sucking sponge feeding dorid (diagrammatic).
А. Retracted position of the buccal bulb.
B. Increased blood pressure in the cephalic
haemocoel (depicted by arrows) and opening of
the ubccal sheath. C. Protracted position of the
buccal bulb; buccal bulb in position for
feeding.

antagonistic activity of circular mus-
culature surrounding the tube to radial
muscles connecting the lumen with the
outer wall of the tube. The lumen is
tripartite and constricted when the radial
muscles are relaxed, whereas the lumen
is triangular and open when the radial
muscles are contracted. The antagonistic
action of the circular muscles to the radial
muscles accentuates the contractions and
dilatations of the lumen of the oral tube.
Negative pressure or suction within the
tube is produced by differential contra-
ctions along the oral tube resulting in
peristaltic activity moving food particles
in an anterior to posterior direction.

436 DAVID K.

Contractions of the extrinsic lateral
buccal retractor muscles and the extrinsic
media! buccal retractor muscles cause
retraction of the buccal bulb after feeding
is accomplished, as suggested by Hancock
(1865). The retraction of the buccal
sheath is aided by contraction of the oral
branches of the columellar muscle. These
muscles can produce a very rapid
retraction of the buccal bulb and the
buccal sheath when the animal is disturbed
while it is feeding.

Studies by Krukenberg (1881) on the
ptyaline gland or ‘“ acidogenen drusen ”
(acidogenic gland) of Doriopsis (= Dendro-
doris) limbata suggested that the tissue
and the secretion of the gland are slightly
acidic as determined by litmus paper. In
the present investigation extracts of the
ptyaline gland of Dendrodoris nigra had
pH values ranging from 6°0to 6°5 as
determined by pH indicator papers.
Krukerberg also found that extracts of the
ptyaline gland were free of peptic, tryptic
and diastatic enzymes, in contrast with
extracts of the digestive gland which
contained all 3 enzymes in abundance.
The active substance of the ptyaline gland
was not characterized.

As previously discussed, the duct of the
ptyaline gland is morphologically peculiar
in that it does not empty into the oral tube
but to the exterior through the mouth.
This feature suggests that the substance
secreted by the ptyaline gland affects the
food material before it is drawn into the
oral tube by suctorial action. Hancock
(1865, p 191) suggested that the secretion
of the ptyaline gland either dissolves food
matter or is toxic to prey because, ‘ The
feeble structure of the buccal organ seems
to suggest the requirements of some such
aid, as, in these animals, there is neither
cutting nor prehensile organs of any
kind. ”

The absence of a ptyaline gland in the
genus Doriopsilla, whose members have
a similar sucking buccal apparatus as

YOUNG

Dendrodoris (Eliot, 1906) and at least one
species of which feeds on sponges
(Ghiselin, 1964), suggests that the secretion
of the ptyaline gland may not be essential
to this type of feeding. If this is true,
however, it is questionable how the
spongin fibres are broken down in order
that the mesenchymal cells and spicules
may be ingested by the suctorial action of
the buccal apparatus.

3. Discussion

Homologies of the buccal apparatus
of the sucking sponge-feeders with that of
the rasping sponge-feeders are difficult
to determine. Both feeding types ingest
similar food but by radically different
methods: one uses a mechanical rasping
action and the other, possibly a chemical
action, followed by mechanical suction.
The odontophore and radula have been
lost in the sucking sponge-feeders through
adaptive evolutionary processes.

Hancock (1865) suggested that the
retractors of the buccal sheath (the
extrinsic lateral buccal retractor muscles)
of the sucking sponge-feeders are homolo-
gous with the retractors of the oral tube
(the extrinsic oral retractor muscles) of the
rasping sponge-feeders. If the oral tube
of a typical rasping sponge-feeder 15
drawn over the buccal mass, and the
odontophore (with all intrinsic mus-
culature involved in its operation) is
removed, the resultant appears like the
buccal apparatus of a sucking sponge-
feeder (Fig. 14, A-C). The extrinsic
medial buccal retractor muscles of the
dendrodorids appear to be homologous
with the extrinsic buccal retractor muscles
of the rasping sponge-feeding dorids.

Eliot (1906, p 664) suggested that the
suctorial tube of the dendrodorids has
apparently replaced the odontophore and
through evolutionary processes the oral
tube has “...been pulled backwards
through the nerve-collar, and the buccal
ganglia have moved with it,..”, The

FEEDING APPARATUS OF DORID 437

salivary glands of the dendrodorids,
though greatly reduced in size, have
retained their position at the esophageal-
buccal junction as in other dorids.
Because a triangular shape of lumen
connected with the passage of food has
arisen in the pyramidellids (Maas, 1965)
and in Philine (Brown, 1934), as well as
in the dendrodorids, it appears that this
shape is mechanically efficient. It is
likely that a maximal change in volume of
lumen is achieved with this shape (Hurst.
pers. comm.).

The absence of a homologue of the
ptyaline gland in the rasping sponge-
feeding dorids suggests an early divergence
of the dendrodorids from the lineage
giving rise to those dorids with a rasping
type of buccal apparatus. A pair of
glands sin‘lar to the ptyaline gland is
found in the muricid prosobranchs.
These glands, which are termed the
““ accessory salivary glands, ” have a
common duct that passes forward to
empty lubricating secretions into the
ventral region of the mouth (Carriker,
1943).

The buccal apparatus of the sucking
sponge-feeders is placed within the anterior
haemocoel similarly to the pleurembolic
proboscis of the prosobranchs: whereas
the buccal apparatus of the rasping sponge-
feeders is comparable in placement to the
acrembolic prosobranch proboscis.
According to Fretter & Graham (1962),
the pleurembolic type of proboscis in the
prosobranchs is more advanced and more
efficient mechanically than the acrembolic
type.

Two prosobranchs, Cerithiopsis tuber-
cularis and Triphora perversa, each have a
long acrembolic proboscis which is passed
through an osculum to the softer inner
tissues of the sponge (Fretter, 1951), in
much the same manner as the buccal bulb
of Dendrodoris nigra. In contrast to the
dendrodorids, however, these proso-
branchs have a pair of jaws that break up

1 eor |

еог 3

lbr

FIG. 14. Hypothetical sequence in the derivation
of a sucking sponge feeding type of buccal
apparatus from a rasping sponge-feedirg type of
buccal apparatus (diagrammatic). А. Prosto-
mium is displaced posteriorly over the buccal
mass of a rasping sponge feeding buccal apparatus
and the portion of the buccal mass posterior to
the dotted line is removed. B. Wall of the buccal
vestibule fuses with that of the buccal mass.
C. Lumen of the buccal mass constricts: buccal
apparatus now imparts an outward appearance
of a sucking sponge-feeding type.

the sponge tissue before it is moved to the
buccal cavity by radular teeth.

Although quite different in morphology,
an example is found in the cephalaspidean
opisthobranch Retusa of а buccal
apparatus which is devoid of an odonto-
phore and a radula (Hurst, 1965). The
lateral muscles and the buccal retractor

438 DAVID K.

muscles of Retusa are similar in function to
the extrinsic medial retractor muscles of
Dendradoris. Although Hurst states that
Retusa probably employs suction as a
means of obtaining food, no protrusion
of the buccal apparatus is reported to
occur.

Ш. Engulfing opisthobranch-feeders
1. Alimentary tract

The engulfing opisthobranch-feeding
dorids are represented by Gymnodoris
okinawae Baba, 1936; G. bicolor (Alder &
Hancock, 1866): С. alba (Bergh, 1877);
G. plebeia (Bergh, 1877) and G. citrina
(Bergh, 1877) of the subfamily Gymnodo-
ridinae (family Polyceridae). The mouth
is anteroventral. lying anterior to the
foot, ventral to the cephalic hood and
between 2 ventrolateral oral tentacles.
Posterior to the mouth is the large mus-
cular buccal apparatus which opens
posterodorsally into the greatly expansible
esophagus (Figs. 15, 16, es).

Free-ending, lobulate salivary glands
(Fig. 15, sg) enter at each side of the
esophageal-buccal junction and open into
the lumen of the buccal mass. The sali-
vary glands, in contrast to those of the
rasping sponge-feeding dorids, closely
adhere to the buccal apparatus. Connec-
tives from the cerebral ganglia overlying
the buccal mass extend ventrally to the
pair of medially connected buceal ganglia
(Figs. 15, 16 bg) ventral to the esophagus.

The esophagus opens into the anterior
end of the thin-walled midgut (Fig. 15,
mg) which is perforated with large
openings leading into the digestive diverti-
cula of the digestive gland (dg). The
midgut is larger and the digestive gland
is smaller than those in the rasping sponge-
feeding dorids. The midgut opens
dorsally into the intestine (in) which is
often so short that there is only an indi-
cation of the characteristic ‘‘ dorid loop ”
of the Doridacea (in the extremely short

YOUNG

intestine of Gymnodoris bicolor no dorid
loop is formed). A small caecum (ca)
opens into the left side of the intestine
at the midgut-intestine junction. The
intestine terminates at the mid-dorsal
anus.

2. Buccal apparatus

Morphology. The buccal apparatus of
engulfing opisthobranch-feeding dorids
may be differentiated into a short, anterior
oral tube (Fig. 16, ot), a dilated, inter-
mediate buccal vestibule (bv) and a
muscular, posterior buccal mass (bm).

The oral tube 1$ comprised of connective
tissue interspersed with muscle fibres and
glands. Sphincter muscles encircle the
oral tube, but unlike the rasping sponge-
feeding dorids, an outer and an inner lip
cannot be distinguished. Oral branches
of the columellar muscle (Fig. 16, ocm)
insert anteriorly in the oral tube and
connect posteriorly to the medial and
lateral branches of the columellar muscle
which in turn extend along the lateral:and
ventral body wall to posterior termina-
tions. Three pairs of muscles, the extrinsic
oral retractor muscles (Fig. 15, eor 1. 2, 3),
insert dorsolaterally in the posterior
edge of the oral tube and extend postero-
laterally to origins in the adjacent body
wall.

The intrinsic buccal retractor muscles,
(Fig. 15, ibr) pass from dorsolateral origins
in each side of the posterior portion of the
buccal mass and insert laterally in the
wall of the oral tube immediately ventral
to the insertions of the extrinsic oral
retractor muscles. A thin layer of intrin-
sic buccal longitudinal musculature (ilb)
overlies the buccal wall and extends from
the anterior edge of the superficial buccal
musculature to the anterior margin of the
buccal mass. Circular musculature forms
the main bulk of the buccal wall. The
inner surface of the buccal wall is lined
with a thin layer of extremely flexible
cuticle. No jaws are present, but a pair

FEEDING APPARATUS OF DORID 439

FIG. 15. Gymnodoris okinawae. Lateral view of the alimentary tract (anterior at right).

FIG. 16. Gymnodoris okinawae. Left sagittal section of the buccal apparatus (anterior at right).

of cuticular plate-like thickenings are
found on both sides of the anterior buccal
wall in Gymnodoris citrina.

The superficial buccal musculature
forms the lateral thickenings of the buccal
mass which provide posterolateral support
for the odontophore. The radular sac
(Figs. 15, 16 rs) projects posteroventrally
from between the lateral thickenings and
forms a slight bulge to the rear of the
buccal mass. As in the rasping sponge-

feeders, the superficial buccal musculature
passes anteroventrally from a postero-
medial origin at the rear of the buccal mass
and inserts at a dorsoventral furrow
marking the anterior edge of the lateral
thickenings.

The only extrinsic muscles of the buccal
mass, the extrinsic buccal retractor muscles
(Fig. 15, ebr), insert in the anterodorsal
portion of the superficial buccal muscu-
lature on each side of the buccal mass.

440 DAVID K.

Their origin is anterodorsal to the buccal
mass in the anterior body wall. The
esophageal retractor muscle (erm), inserts
in the dorsal esophageal wall posterior to
the esophageal-buccal junction and passes
anteriorly to origins in the body wall
immediately dorsal to the origin of the
extrinsic buccal retractor muscles.

As in the rasping sponge-feeding dorids,
the odontophore is comprised of the
radula and the lateral cartilages with their
complex of odontophoral musculature.
The more pronounced differences between
the components of the odontophore of
the engulfing opisthobranch-feeders and
those of the rasping sponge-feeders are:
(1) the radular membrane is shorter and
broader; (2) the lateral cartilages are
thinner and unconnected; (3) the medial
radular retractor muscles are inserted
more posteriorly along the inner surface
of the radular membrane; and (4) the
radular teeth are narrow and more elon-
gate.

Function. The feeding movements of
the buccal appratus are described from
observations of Gymnodoris okinawae and
G. bicolor in the process of devouring their
prey. Gymnodoris okinawae feeds on
members of the saccoglossan family
Elysiidae, whereas G. bicolor feeds on
members of its own genus, Gymnodoris.
Eversion of the entire buccal apparatus
results in the odontophore projecting
anteroventrally in relation to the dorsally
situated esophageal orifice. The odon-
tophore is spread and the radular teeth
are erected. The prey is grasped by the
radular teeth following closure of the
odontophore. The odontophore 15
retracted and the prey is drawn into the
esophagus. If the prey is large, these
movements may continue until the entire
animal is passed progressively into the
esophagus by rhythmical in and out
movements of the odontophore.

Versatility in the feeding movements of
this type of buccal apparatus was indi-

YOUNG

cated by observations of Gymnodoris
bicolor feeding on the egg masses of its
prey Gymnodoris okinawae. The sequen-
tial feeding movements in this process
are: (1) the oral tube parts; (2) the buccal
wallisexposed as a narrow vertical slit; (3)
the buccal lumen expands; (4) the odon-
tophore protrudes; (5) the radula is
spread and the teeth are erected; (6) the
odontophore narrows and the radular
teeth grasp the egg mass; (7) the odonto-
phore retracts and a portion of the egg
mass is torn away; and (8) the lumen of
the buccal mass is reduced to a slit-like
aperture. The entire sequence occurs
in 5 second intervals at 26°C.

The buccal mass is protruded to a
varying extent according to whether the
animal is feeding on motile prey or egg
masses. While feeding on egg masses,
the buccal mass moves in a sequence
similar to that of the buccal mass of
rasping sponge-feeding dorids; the main
difference is in the operation of the
odontophore. Because of this similarity
in the sequence of feeding movements,
only the functional morphology of the
buccal apparatus involved in the prey-
engulfing sequence will be discussed.

Protrusion of the buccal apparatus 1$
brought about by increased blood pressure
in the cephalic haemocoel (Fig. 17 A-C).
In contrast with the same process in
rasping sponge-feeding dorids, the buccal
mass in the gymnodorids is protruded
outwardly from the prostomium and
entirely everted. Although the longitudi-
nal intrinsic buccal muscles are involved
in protraction of the odontophore and
foreshortening of the buccal mass, the
extrinsic muscles of the buccal apparatus
are involved only in the retraction process.
Because the extrinsic buccal muscles have
anterior origins, greater protraction of
the buccal mass is possible than in the
rasping sponge-feeders which have
extrinsic buccal muscles with posterior
origins.

FEEDING APPARATUS OF DORID 441

ocm

FIG. 17. Protraction of the odontophore in an
engulfing opisthobranch-feeding dorid (diagram-
matic). A. Retracted position of the odontophore.
В. Increased blood pressure in the cephalic
haemocoel (depicted by arrows) and opening of
the lumen of the oral tube and the buccal mass.
C. Protracted position of the odontophore with
the entire buccal apparatus everted; radula open
and in position to grasp prey.

The functional differences in the
operation of the odontophore of engulfing
opisthobranch-feeders and of rasping
sponge-feeders may be explained, in part,
by 2 major factors. Firstly, the odonto-
phore in the gymnodorids may be widely
spread because the lateral cartilages have
no connections of connective tissue.
Secondly, the radula may be spread wider
thar in the rasping sponge-feeders because
the medial redular retractor muscles are

inserted more posteriorly on each side
of the radular membrane.

The radular membrane is pulled over
each lateral cartilage by contraction of the
marginal radular protractor muscles.
The lateral tension upon the гадшаг
membrane erects the elongate radular
teeth. Simultaneously, contraction of
the anterior radular protractor muscles
protracts the radula and exposes all the
functional radular teeth.

The odontophore is closed by contract-
ion of the medial radular retractor muscles
which also retracts the radula and directs
the radular teeth inward and backward.
The elongate radular teeth pierce the
epidermis of the prey, thereby exerting a
firm grip while the prey is drawn into the
esophagus.

Retraction begins with the withdrawal
of the esophagus by the contraction of the
esophageal retractor muscle. This process
is accompanied by a decrease in blood
pressure in the cephalic haemocoel.

Retraction of the odontophore and the
everted buccal mass is accomplished by
contraction of the extrinsic and intrinsic
buccal retractor muscles. Finally, the
oral tube is retracted by contraction of the
extrinisic oral retractor muscles and the
oral branches of the columellar muscle.
The shape of the buccal mass is maintained
throughout the entire process by support
given by the superficial buccal musculature
and muscles of the buccal wall.

3. Discussion

The buccal apparatus of the engulfing
opisthobranch-feeders exhibits several
interesting differences from that of the
rasping sponge-feeders. The main mor-
phological differences enabling the gymno-
dorids to devour large prey are: (1) the
mouth and buccal! apparatus are anteriorly
directed; (2) the salivary glands adhere
only to the buccal mass; (3) the oral
region is short; (4) the extrinsic oral
retractor muscles insert dorsolaterally in

442 ES DAVID K: YOUNG

the oral tube; (5) the extrinsic buccal
retractor muscles have anterior origins;
(6) the lateral cartilages are unconnected ;
(7) the medial radular retractor muscles
have posterior insertions along the radular
membrane; (8) the radular teeth are
narrow and elongate; and (9) the eso-
phagus is connected anteriorly to the
body wall by the esophageal retractor
muscle.

The buccal apparatus of the cephalas-
pidean opisthobranch Philine (Hurst,
1965). which has asimilar engulfing type of
feeding, exhibits several interesting homo-
logies with that of the engulfing
opisthobranch-feeders. The most pro-
nounced of these is the apparent homology
between the extrinsic buccal retractor
muscles of Gymnodoris and the extrinsic
retractor pair И of Philine. These muscles
apparently serve as retractors of the buccal
mass in both animals, although Hurst
(1965) suggested that extrinsic retractor
muscle pair II in Philine aids initially in
protraction of the buccal mass. In
contrast with the retraction of the buccal
apparatus in Philine, where the esophagus
is withdrawn lastly and with difficulty
(Hurst, 1965). the retraction of the esopha-
gus in Gymnodoris is brought about as а
preliminary step in the retraction process
by contraction of the esophageal retractor
muscle; - а. anuscle: not ‘present. in
Philine.

Similar engulfing processes are accom-
lished by gastropods other than Philine
and Gymnodoris. Examples of a buccal
apparatus which functions by protraction
of the odontophore, gripping of prey by
fang-like radular teeth and drawing the
prey into the esophagus by retraction of
the odontophore is found in the proso-
branch Janthina (Graham, 1965) and in
the pulmonate Testacella (Lacaze-Duthi-
ers, 1887: Webb, 1893). Graham (1965)
has pointed out that the feeding
mechanism of Philine, lanthina and
Testacella differs mainly in the extent of

protraction of the odontophore and ever-
sion of the buccal mass.

ГУ. Boring polychaete-feeders
1. Alimentary tract

The boring polychaete-feeders are solely
represented by Okadaia elegans of the
family Vayssiereidae. This minute dorid
is rarely longer than 4 mm as an adult.
In comprehensive morphological treat-
ments of Okadaia elegans, Baba (1931,
1937) reports that the alimentary tract
commences at a ventral mouth and passes
progressively through a stomodaeum lined
with ciliated cells and mucous gland cells;
a large, jawless buccal mass lined anteriorly
with chitin; an elongate esophagus lined
with ciliated cells and internal folds: a
thin-walled. U-shaped stomach perforated
with openings from a 3-4 lobed liver: and
an anteriorly directed intestine that
describes a typical dorid loop and opens at
a mid-dorsal anus. Although the liver
is divided into 3 or 4 lobes, Baba (1931,
p 76) reports that it is unramified and that
it should be considered as the holohepatic
type.

2. Buccal apparatus

Morphology. The pear-shaped buccal
apparatus of Okadaia elegans, as figured
in sagittal section by Baba (1937, Fig. 9),
encloses an odontophore and radula.
No salivary glands are present. Muscle
fibers, which arise from the base of the
odontophore, surround the radula sheath
and terminate at the tip of the odonto-
phore and. .‘‘control the protraction and
retraction of the odontophore ” (Baba,
1937, р 160). The radula bears teeth with
the formula, 35-44 x 3.0.3. They are
differentiated as follows: the Ist lateral is
hamate, tipped with 3 spiny denticles; the
2nd lateral is simply hamate; and the 3rd
lateral is plate-like (Baba, 1937, p 159).

A pair of “ pharyngeal valves ” is
reported by Baba (1937, p 160-161) to

PEEDING APPARATUS OF DORID 443

project downward from the posterodorsal
wall of the buccal mass. These structures,
which bear ciliated cells and cuticle, are
devoid of gland cells and are sensory in
function according to Baba.

Function. Observatiors of specimens
of Okadaia elegans in the process of feed-
ing on spirorbid polychaetes indicate that
there are 2 distinct phases of feeding:
the boring phase and the engulfing phase.
Although Baba (1937) states that Oxadaia
elegans feeds on Spirorbis, he fails to
describe the mechanism for feeding upon
such prey enclosed in calcareous tubes.
The purpose of this discussion, therefore,
is to report the peculiar feeding habit of
Okadaia elegans.

During the boring phase, each individual
exhibits an up and down movement of the
head while the rest of the animal remains
in a fixed position. A round hole, 57 to
88/ in diameter, is bored near the posterior
portion of the calcareous tube. No tube
of a spirorbid polychaete has been obser-
ved with more than one bored hole.
After the hole is bored, the dorid extends
its odontophore through the hole and
grasps the polychaete with its erected
radular teeth. Thereafter, the feeding
mechanism is very much like that of the
engulfing opisthobranch-feeders; the
polychaete is drawn progressively into the
esophagus by ш and out movements of
the odontophore and swallowed whole.
Depending on the size of the predator
and prey, the boring phase takes from
35 minutes to 6 hours and the engulfing
phase from 15 to 30 minutes Гог
completion.

The radular teeth of Okadaia elegans
serve at least 2 different functions. The
serrated Ist lateral tooth is probably
utilized as a boring tool, whereas the more
elongate, hooked 2nd lateral tooth serves
in grasping the prey.

3. Discussion

Whereas the swallowing phase of the
boring polychaete-feeding dorids is much
like that of the engulfing opisthobranch-
feeding dorids, the boring phase is unique
among the Opisthobranchia. Members
of the Prosobranchia in the families
Muricidae and Naticidae also feed on
animals enclosed by a hard calcareous
outer covering. Mechanical boring of
the shells of molluscan prey by muricacean
borers has been demonstrated by such
workers аз Pelseneer (1925), Graham
(1941) and Jensen (1951): but .Carriker
(1959) has more recently shown that the
boring mechanism in these animals 1$
aided by chemical activity.

It is not known if chemical action assists
the boring process in Okadaia elegans.
The histological sections of Baba (1937),
however. demonstrate no glandular
structures in Okadais elegans which might
assist boring as does the accessory boring
organ in Uresalpinx cinerea and Eupleura
caudata (Carriker, 1959).

ACKNOWLEDGMENTS

Grateful acknowledgment is due Dr. E. Alison
Kay (University of Hawaii, Honolulu, U.S.A.)
for her interest and aid in all aspects of this study.
The author appreciates the comments and criti-
cisms of the manuscript by Dr. Melbourne
К. Carriker (Systematics-Ecology Program,
Marine Biological Laboratory, Woods Hole,
Mass. U.S.A.), Dr. Anne Hurst (University of
Reading, Reading, U.K.) and Dr. Michael
Ghiselin (University of California, Berkeley,
Calif., U.S.A.). This study was supported by a
Marine Science Graduate Research Fellowship
from the Bureau of Commercial Fisheries, and
the final aspects of the work and preparation of
the manuscript were done in the Systematics-
Ecology Program under support of Grant GB-
4509 from the National Science Foundation,
Washington, D.C., to the Systematics-Ecology
Program.

! Research subsequent to that reported in this paper indicates that tube-boring by
O. elegans is aided by secretions from a gland within the stomodaeum (See Young, 1969).

444 DAVID К. YOUNG

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FEEDING APPARATUS OF DORID 445

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903-907.

RESUME

LA MORPHOLOGIE FONCTIONNELLE DE L'APPAREIL
DIGESTIF DE QUELQUES NUDIBRANCHES DORIDIENS DE
L’INDO-PACIFIQUE OUEST

О.К. Young

Quarante-huit espèces de doridiens de l'Indo-Pacifique Ouest ont été groupées en types
nutritionnels généraux, chaque type étant caractérisé par les adaptations morphologiques
de Vappareil buccal, en relation avec une nourriture spécialisée. La discussion porte
sur la morphologie fonctionnelle de Гаррагей buccal de 4 types nutritionnels: (1) racleurs

d'éponges, (2) suceurs d'éponges. (3)
polychetes.

avaleurs d'opisthobranches, (4) perceurs de

L’extension de la radiation adaptative chez les Doridiens est particulierement évidente,
en ce qui concerne la nourriture et le mode de nutrition. D'évidentes adaptations mor-
phologiques à la nutrition ont été montrées par l'étude de la structure de l'appareil buccal
Les représentants de chaque famille de doridiens montrent une structure similaire de
Pappareil buccal et des modes de nutrition semblables. Du fait que les éléments de
l'appareil buccal des doridiens sont utilisés par les taxonomistes comme caractères pré-
pondérants, il n'est pas étonnant que les doridiens soient groupés dans des sortes de types
nutritionnels qui se superposent aux groupes taxonomiques.

Les mangeurs d'éponges, qui comptent 7-8 représentants parmi les doridiens étudiés.
sont représentés par les Dorididae et les Hexabranchidae racleurs d'éponges et par les
Dendrodorididae suceurs d'éponges. Les avaleurs d’opisthobranches sont représentés
par les 5 especes de Gymnoridinae (famille des Polyceridae) et les perceurs de polychetes

par une seule espece de Vayssiereidae.

RESUMEN

MORFOLOGIA FUNCIONAL DEL APARATO ALIMENTICIO
DE ALGUNOS NUDIBRANQUIOS DEL INDO-PACIFICO
OCCIDENTAL

О. К. Young

Cuarenta y ocho especies de dóridos del Indo-Pacifico occidental se agruparon según
los tipos de su alimentación general, cada tipo con adaptaciones morfológicas carac-
teristicas del aparato bucal asociado con alimentación especializada. Se discute la
morfologia funcional de 4 tipos así separados: (1) raspadores de esponjas, (2) suc-
cionadores de esponjas, (3) sumidores de opistobranquios, y (4) perforadores de

poliquetos,

446 DAVID K. YOUNG

Extensa radiación adaptiva se evidencia en los dóridos, especialmente en los varios
tipos de alimento y manera de alimentarse. El aparato bucal presenta adaptaciones
morfológicas conspicuas. Miembros de cada familia de los Doridacea exhiben estructura
similar del aparato bucal y hábitos alimenticios similares. Parte del aparato bucal se
han aplicado a la taxonomia como caracteres principales, y asi no es extraño que los
dóridos se puedan separar en tipos alimenticios paralelos a los taxonómicos.

Los que se alimentan de esponjas —comprendiendo 7/8 de los dóridos estudiados—,
estan representados por los raspadores Doridiidae y Hexabranchidae, y por los chupadores
Dendrodoriidae. Los sumidores, o engullidores, de opistobranquios estan representados
por 5 especies de Gymnodoridiinae (family Polyceridae) y los perforadores de poliquetos
por una sóla especie de Vaysseiereidae.

El aparato bucal de los dóridos ha experimentado evolución adaptiva asociada con
hábitos alimenticios especiales. Diferencias en alimentación de los 4 tipos se explican
por differencias (o pérdida) estructurales de dientes radulares y modificaciones de la
musculatura que opera en la masa bucal y en la rádula. Se dan las similaridades entre
los mecanismos de alimentación en cada tipo, y aquellos encontradas en otros
opistobranquios, prosobranquios y gastrópodos pulmonados.

ABCTPAKT

ФУНКЦИОНАЛЬНАЯ МОРФОЛОГИЯ АППАРАТА ДЛЯ ЗАХВАТА
ПИЩИ У НЕКОТОРЫХ ИНДО-ЗАПАДНО- ТИХООКЕАНСКИХ
ГОЛОЖАБЕРНЫХ МОЛЛЮСКОВ ДИРИДИЛ

ЛК. ENTE

Сорок четыре вида Индо-западно-тихоокеанских Поридид были сгруппиро-
ваны в соответствии с общим характером типа их питания, каждый из кото-
рых характеризуется морфологическими адаптациями их ротового аппарата.
Рассматриваются 4 типа их питания: 1) скребущие губкоеды, 2) сосущие гу-
бкоелы, 3) заглатывающие задне-жаберных моллюсков и 4) сверлящие формы,
питаюшиеся полихетами.

Экстенсивная адаптивная радиация среди Лоридид особенно заметна по
разнообразию их пищи и различным способам питания. Хорошо заметные мор-
фологические адаптации к пище наблюдаются в стооении ротового (буккаль-

ного) аппарата. Моллюски из каждой гоуппы семейства Доридид имеют сход-
ство в устройстве ротового аппарата и в способе питания. Ввиду того, что
части ротового аппарата Доридид служат главными систематическими призна-
ками, не удивительно, что. они группируются в довольно дискретные группы
по типам питания, параллельным и таксономическим группам. Губкоеды (7- 8
форм из изученных Доридид) представлены скобляшими, питающимися губками

Dorididae и Hexabranchidae, а также сосущими губкоедами из Dendrodoridae. Формы
заглатывающие Ophisthobranchia представлены пятью видами из Gymnodoridinae
(семейство Polyceridae) и сверлящими полихетофагами (единичные виды из
Vayssiereidae).

Буккальный аппарат Диридид претерпел адаптивную эволюцию в связи CO
специализацией образа их питания. Различия в питании среди 4 указанных
типов объясняется различной структурой (или утерей) радулярного зуба и
модификацией мускулатуры, принимающей участие в работе буккального комп-
лекса радулы.

Рассматривается сходство между механизмом захвата пищи к каждом типе
питания и тем, который наблюдается у других MONJINWCKOB-Opisthobranchia, Pro-
sobranchia и Pulmonata Gastropoda.

MALACOLOGIA, 1969, 9(2); 447-500’.

THE STRUCTURE: AND* FUNCTION OF THE DIGESTIVE
SYSTEM: OB -THE-MUD SNAIL
NASSARIUS OBSOLETUS (SAY)!

by Stephen C. Brown?

Department of Zoology, University of Michigan,
Ann Arbor, Michigan, U.S.A.

ABSTRACT

The American Atlantic coast mud snail, Nassarius obsoletus (Say) is a member of the
typically carnivorous rachiglossan Gastropoda. In nature, however, N. obsoletus is a
non-selective deposit-feeder subsisting almost entirely on ingested sand and mud. The
present study was undertaken to clarify the mechanism of functioning of the digestive
system of this animal.

Anatomical and histological studies indicate that Nassarius obsoletus has all of the
structural modifications associated with assumption of a carnivorous mode of existence.
These modifications include: an elongate protrusible proboscis; rachiglossan radular
dentition; an elongate, movable siphon and bipectinate osphradium; well-developed
valve of Leiblein, gland of Leiblein, and salivary glands; a simplified stomach possessing
a very reduced gastric shield; no efficient ciliary sorting areas; and well-developed
muscular layers surrounding the alimentary canal. In contrast to these clearly
carnivorous characteristics, N. obsvletus possesses a Mucoprotein crystalline style within
its stomach—a feature associated with structural adaptation for handling a herbivorous
diet. Histochemical studies indicate that the midgut gland contains enzymes capable
of splitting esters and glucuronides and thus for metabolizing some of the principal con-
stituents of algae. Feeding experiments using finely divided particulate material and
histochemical localization of phosphatase activity both indicate that phagocytosis and
intracellular digestion do not occur. In vitro enzyme analyses of tissue homogenates of
the various digestive organs reveal the presence of esterase, lipase, a-amylase, protease,
and several disaccharases. Analyses of stomach fluid and crystalline styles similarly
reveal the presence of the hydrolytic enzymes extracellularly within the lumen of the
stomach. A review of the feeding habits and behavior is presented along with physio-
logical evidence that the crystalline style aids in the digestive process and is therefore
truly functional, rather than being merely a remnant of the mucous fecal string.

It is concluded from the data presented that Nassarius obsoletus, although structurally
possessing all the features of a typical carnivorous rachiglossan nevertheless is able to
subsist almost entirely on a diet of algal detritus; that it possesses the hydrolytic enzymes
necessary to breakdown the principal constituents of algae; that the initial breakdown
occurs extracellularly; that phagocytosis and intracellular digestion do not occur; and
that absorption of soluble digestion products occurs most probably in the midgut gland
or epithelium lining the stomach-intestine.

' Submitted to the Department of Zoology of The University of Michigan in partial fulfilment of the
requirements for the degree of Doctor of Philosophy.

* Present address: Department of Biological Sciences, State University of New York, Albany, New York
U.S.A 12203, ae

447

448 STEPHEN C. BROWN

CONTENTS

eel SIINGRRODUGHON EE о 448
Il. ANATOMY AND HISTOLOGY ... 448
1. Materials and methods ....... 448
2. Organ and tissue structure . . . . .. 449
SMEVAUATON ORALE EEE 468
Ш. ENZYME HISTOCHEMISTRY... . 472
1. Materials and methods ....... 472
DARE USO a sess ct om NES сию 473
2 sEvaluationtofidatare a EEE 474
IV. IN VITRO ENZYME ANALYSES .. 477
1. Materials and methods ....... 477
DIR ESUIES ES, AA RTE A 479
3. Bvaluationtofidatam eas) eee eee 481

У. ASPECTS OF DIGESTIVE PHYSI-
OLOGY AND BEHAVIOR ..... 484
VI. GENERAL DISCUSSION. ...... 489
ACKNOWLEDGMENTS .......... 494
LITERATURE CIRTEDA ER Aer olen. 494

I. INTRODUCTION

The gastropod genus Nassarius (Proso-
branchia, Neogastropoda) is world-wide
in distribution. A representative of this
genus, Nassarius (Ilyanassa) obsoletus
(Say), is one ofthe most abundant animals
of the intertidal mud flats along the Atlan-
tic Coast of North America.

Although much of the basic biology of
Nassarius obsoletus has not been studied
in detail, the animal has, nevertheless,
been the subject of many experimental
and descriptive studies. These have been
in the areas of: experimental embryology
(Crampton, 1896; Morgan, 1933; Dan &
Dan; 1942: (Clement; 1952. ` 1956, 1960
and 1962; Clement & Lehmann, 1956a
and 1956b: Berg € Kato, 1959; Cather,
1959, 1963 and 1967; Collier, 1960 and
1961; Clement & Tyler, 1967); larval
development (Scheltema, 1956, 1961.
1962a, 1962b and 1965; Paulson & Schel-
tema, 1967); behavior and physiological
ecology (Dimon, 1905; Batchelder, 1915;
Stephens, et al, 1953; Jenner & Chamber-
Jain, 1955; Jenner, 1956a, 1956b, 1957
and 1958; Baylor, 1958; Brown, ef al,
1959 and 1960; Scheltema, 1964; Naga-
bhushanam & Sarojini, 1965: Carr, 1967a

and 1967b); and parasitology (Martin,
1938 and 1939; Stunkard, 1938a, 1938b
and 1961; Rankin, 1940; Stunkard &
Hinchliffe, 1952: Sindermann, 1960;
Printz, 1962).

The results of several of these studies
point to the fact that the feeding habits
and digestive system of Nassarius obso-
letus show features which are quite
unusual for a member of the Neogastro-
poda. Although neogastropods are re-
garded as primarily carnivorous (Fretter
& Graham, 1962; Hyman, 1967) and all
other species of Nassarius which have
been studied are classified as carnivores
(Yonge, 1954; Martoja 1964), Nassarius
obsoletus has been reported (Jenner,
1956b) to possess a crystalline style, a
structure considered to be a definitive cha-
racteristic of purely herbivorous molluscs
(Yonge, 1930). Scheltema (1956 and 1961)
has presented evidence strongly suggesting
that the feeding habits and perhaps even
nutritional requirements of adult N. obso-
letus are of prime importance in deter-
mining the time and place of settling and
metamorphosis of their planktonic veliger
larvae.

The present study was undertaken to
elucidate the mechanism by which the
digestive system of this animal functions.
The results are presented in four parts:
tissue and organ structure; enzyme histo-
chemistry; in vitro enzyme analyses; and
digestive physiology and behavior. A
brief evaluation is presented at the end
of each part, dealing with that section.
The general discussion at the end attempts
a synthesis of the data into a coherent
picture of structure and function.

Il. ANATOMY AND HISTOLOGY

1. Materials and methods

All descriptions are based on fresh and
preserved specimens collected from the
vicinities of Woods Hole and Barnstable
Harbor. Massachusetts, In some cases,

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 449

animals were maintained at the Univer-
sity of Michigan in sea-water aquaria on
a diet of frozen shrimp prior to fixation
or examination. Dissections were carried
out on living animals and also on those
previously hardened in ten percent for-
malin.

For most general histological work
Carnoy’s, Bouin’s, Zenker’s. Helly’s and
Atkins’ fixatives were used, with the first
two giving the best nuclear detail while
the last three yielded the clearest overall
histological results. Materials so fixed
were paraffin embedded, sectioned at
4-10 microns, and stained with Heiden-
hain’s iron hematoxylin, Weigert’s iron
hematoxylin with Orange G, Heiden-
hain’s azan, Mayer’s mucicarmine, and
Bismarck brown with methyl green. In
addition, some salivary gland and midgut
gland material was fixed in acrolein or
glutaraldehyde and embedded in Epon
according to the method of Luft (1961).
This Epon-embedded material was then
sectioned at one-half to 2 microns on a
Porter-Blum ultramicrotome with a glass
knife and subsequently stained with Azure
В bromide at pH 8:0, Weigert’s iron
hematoxylin with Alcian blue, or Tolui-
dine blue in 2:5%, sodium carbonate.

Special techniques employed for the
detection of tissue components and for
the characterization of mucins included:
the coupled tetrazonium reaction for
proteins, using Fast blue B salt as coupler
(Burstone, 1955): the DMAB-Nitrite me-
thod for tryptophan on formalin-fixed
tissues (Adams, 1957): the Periodic acid
—Schiff (PAS) technique for vicinal
hydroxyl groups using Lillie’s ‘cold
Schiff ” reagent (Lillie, 1965); the PAS
reaction preceded by digestion in 1/1000
malt diastase for one hour; the standard
toluidine blue method for metachromatic
substances (Pearse, 1960); toluidine blue
preceded by digestion for up to 24 hours
in bovine testicular hyaluronidase; the
Alcian blue method for acid mucopoly-

saccharides carried out at a pH below 2
(Steedman. 1950; Mowry, 1963); the
combined Alcian blue—PAS technique
according to Mowry (1963); the dialysed
iron method for acid mucopolysaccharides
(Hale, 1946; Mowry, 1963); and the
methylene blue extinction technique ac-
cording to Dempsey & Singer (1946). In
addition, formalin-fixed tissue was stained
for calcium with Nuclear fast red accord-
ing to the method of McGee-Russell
(1958) and endogenous iron was detected
by the Prussian blue reaction on formalin-
fixed. paraffin embedded material.

2. Organ and tissue structure

The digestive tract of Nassarius obso-
letus (Fig. 1) is similar to those of the
European species, N. reticulatus, and N.
incrassatus, figured by Fretter & Graham
(1962) and Martoja (1964). At the apex
of the long pleurembolic proboscis lies
the buccal cavity. A pair of salivary
ducts open into the dorsal posterior
aspect of this cavity just anterior to the
level where the esophagus originates.
The long esophagus can be divided, fol-
lowing Graham’s (1939 and 1941) termi-
nology, into the following regions: the
anterior esophagus, extending dorsal to
the radular mass from the buccal cavity
to the valve of Leiblein; the mideso-
phagus, commencing with the valve of
Leiblein. proceeding through the nerve
ring—-salivary gland complex, and ter-
minating posterior to the gland of Lel-
blein and its opening; and the poste-
sophagus, continuing posteriorly and end-
ing at its stomach opening which lies at
a level between the posterior caecum and
the anteriorly-directed style sac. The
posterior and anterior midgut glands
almost completely envelop the caecum
and style sac, respectively. Anteriorly
from the style sac, the intestine makes a
sharp S-curve at the level of the heart
and kidney and then arches forward
dorsally within the mantle. A_ rectal

450 STEPHEN. С. BROWN

AMG

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 451

papilla protrudes from the roof of the
mantle cavity on the right side.

Buccal region: The ventrally-directed
triangular mouth delimits the anterior
border of the buccal cavity. The cavity
itself (Figs. 2 and 3) is roughly triangular
in cross section. As it extends posteriorly,
a horizontal partition divides it into a

dorsal chamber which soon leads into the
anterior esophagus and a ventral chamber
(Fig. 3, C-E) which encloses the odonto-
phore and radular apparatus (not shown).

The buccal cavity is lined with a smooth
layer of simple columnar epithelium
(Fig. 2, NCE) the cells of which have
basally located oval nuclei. The cells

Е. 1.

has been uncoiled slightly for illustrative purposes.

lowing figures, see Key to Abbreviations below:

AE Anterior esophagus
AMG Anterior midgut gland
BC Buccal cavity

BM Basement membrane
BV Blood vessel

midgut gland

EEE Ciliated columnar cell

CE Ciliated epithelium

CF Ciliated folds

Cil Cilia

CM Circular muscle

CP Conical papilla

ES Outline of crystalline style
(CIE Connective tissue

Cut Cuticle

DC Dorsal chamber

DF Remnants of primitive dorsal fold
E Eye

EMC Epithelium of mantle cavity
E Foot

G Granules in lumen of salivary duct

GE Epithelial granule cell

GC,, GC, Granule cells, types | and 2, of salivary
gland

GCF Granule cell fragments

GL Gland of Leiblein

GS Gastric shield

H Haemocyte

Г, Ie Regions | and 2 of intestine

IG Intestinal groove

Ik, Lumen of gland or duct

LM Longitudinal muscle

LMB Longitudinal muscle bundles

LMS Longitudinal muscle sheath

BES Lateral sulcus

M Mucous cells

MaT Major typhlosole

MC Mantle cavity outline

ME Midesophagus

The digestive system of Nassarius obsoletus, viewed dorsally. The apex of the visceral mass
For interpretation of the lettering on this and fol-

MG Midgut glands

MGC Mucous goblet cell

MGD Duct of midgut gland

MiT Minor typhlosole

Mo Mouth

MO Midgut gland openings

MP Mucous cells of proboscis outer epi-
thelium

MS Mucus string adherent to style

Mu Mucin in salivary duct

N Nerve

NCE Non-ciliated columnar epithelium

Nu Nucleus

OPE Opening from posterior esophagus

B Proboscis

PE Posterior esophagus

PG Pigment Granules

PMG Posterior midgut gland

PsE Pseudostratified epithelium

R Rectum

RCC Ring of ciliated cells

RI Refractile inclusions

RP Reaction product

5 Shell outline

SD Salivary duct

SG Salivary gland

Si Siphon

Sp Septum

SR Stomach region

SS Style sac

SSA Saddle-shaped area of stomach

StH Style head

Sts Style shaft

at Tentacle

TE Triangular cell

TMC Expanded tip of mucous cell
TME Thickened wall of midesophagus

TMF Transverse muscle fibers
Ty Typhlosole

VC Ventral chamber

VG Ventral groove

VL Valve of Leiblein

452 STEPHEN C. BROWN

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DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 453

are non-ciliated but often contain very
fine black pigment granules scattered in
the apical 1/3 of the cells. Underlying
the epithelial layer is a prominent base-
ment membrane which stains very strongly
with Schiff’s reagent or with aniline in
preparations stained with Heidenhain's
Azan. Immediately beneath this base-
ment membrane lies a thin irregular layer
of longitudinally directed muscle fibers
interspersed with a rather loose connec-
tive tissue. Along the walls of the buccal
cavity and beneath the muscle layer lie 4
large concentrations of mucous gland
eellss(Eig. 2, М; and Fig. 29). “These
large gland cells have dense basally
located semilunar nuclei and are of the
unicellular type, each communicating with
the lumen of the buccal cavity by a con-
spicuous neck which can be traced through
the muscle layer and basement mem-
brane and emerging between the cells of
the lining epithelium. The gland cells
contain a PAS-positive acid mucopoly-
saccharide as shown by the PAS reaction,
toluidine blue metachromasia, the Hale
and Alcian blue techniques, and by a
methylene blue extinction point of less
than 2.

Underlying these elements is а large
haemocoelic cavity traversed by three sets
of muscles directed as follows: a thin
continuous band of circular muscles
(Fig. 2. CM) loosely enveloping the buccal
complex; 4 sets of Jongitudinal muscle
bundles (LMB) lying in the ventral half
of the proboscis; and an irregular com-
plement of transverse muscle fibers (TMF)
inserting in the connective tissue underly-

ing the proboscis epithelium. Аз stetad
above, the salivary ducts empty dorso-
laterally into the rear of the buccal cavity.
In cross sections taken at the posterior
levels of the cavity, the terminal portions
of the salivary ducts can be seen lateral to
the mucous gland cells and just beneath
the circular muscle layer (SD). The
salivary ducts at this level are composed
of a very thin endothelium surrounded
by a relatively thick coat of circularly
directed smooth muscle.

Anterior esophagus: The anterior eso-
phagus. like the rest of the esophagus, is
characterized by the presence of con-
spicuous longitudinally folded walls
(Fig. 4). These folds, in the anterior
esophagus, are of similar size with the
exception of the 2 folds which occupy the
mid-ventral position (DF). These two
folds are somewhat larger than the rest
and the furrow between them is noticably
larger. As Graham has shown (1939),
these folds are the remnants of the primi-
tive dorsal folds which have migrated
ventrally and have thus expanded the
originally dorsal food channel to include
virtually the entire area of the esophagus
with the exception of the present mid-
ventral furrow.

The epithelium lining the anterior eso-
phagus is of the simple columnar type
having oval subcentral nuclei (Fig. 5).
These epithelial cells, in contrast to those
of the buccal cavity, possess long cilia.
These ciliated cells are strongly acido-
philic at their bases, but exhibit increasing
bosophilia at their apices. A prominent
basement membrane underlies the epithe-

FIG. 2. Cross-section of the proboscis at the posterior end of the buccal cavity. Heidenhain’s Azan.

FIG 3.

Relationship of buccal cavity to proboscis, diagrammatic. A. Anterior of proboscis, viewed

dorsally, epidermis partially cut away. B.-E. Sections through levels a-a’ to d-d’, respectively.

FIG. 4. Cross-section of anterior esophagus in the region of the middle of the proboscis. Heidenhain’s

Azan.

FIG. 5. Detail of wall of anterior esophagus, in cross-section. Weigert’s iron haematoxylin-Alcian

blue.

454 STEPHEN C. BROWN

lial layer. Immediately below this mem-
brane is located a heavy continuous layer
of longitudinally directed muscle bundles
(Fig. 4, LM) interlaced at irregular inter-
vals with connective tissue. A continuous
circular layer of muscle (CM) surrounds
the longitudinal muscle fibers.

A distinctive feature cf the anterior
esophagus is the presence of mucous
gland cells lying beneath the longitudinal
muscle layer (Figs. 4 and 5, M). Most
of these mucous cells lie outside the cir-
cular muscle coat, but a few of the cell
bodies may be found between the 2
muscle layers. These submucosal gland
cells are similar in structure to those
underlying the buccal cavity, having
similar dimensions and dense semilunar
nuclei disposed towards the base of the
cells. The mucin within these cells, a
PAS-positive acid mucopolysaccharide, is
histochemically identical to that of the
buccal cavity gland cells (see Table | for
a comparison of staining properties). The
necks of the mucous cells pass through
the muscle layers and basement mem-
brane and often dilate at the level of the
epithelium to become two to three times
as wide as the adjacent ciliated columnar
cells (Fig. 5). There are no goblet mucous
cells among the ciliated columnar cells
lining the lumen of the anterior esophagus.

The salivary ducts accompary the
anterior esophagus along the ventro-
lateral margins, being loosely attached to
the circular muscle layer by strands of
connective. tissue (Fig. 4, SD). The
ducts at this level, in contrast to their
appearance in the region of the buccal
cavity, are composed of a ciliated cuboidal
epithelium a single layer thick surrounded
by a very thin coat of connective tissue.
The lightly-staining nuclei are round and
located in the center of the cells. The
cytoplasm is uniformly acidophilic with
no trace of basophilia. In some prepa-
rations the salivary ducts at the level of
the anterior esophagus contain granules

which stain intensely with acid dyes,
Heidenhain’s hematoxylin, and several
histochemical reagents (Fig. 16 G). Gra-
nules of the same size with identical stain-
ing characteristics have been observed in
the salivary glands and will be more
completely described below.

Valve of Leiblein: The anterior esc-
phagus terminates posteriorly near the
base of the proboscis at a pear-shaped
organ (Figs. 1, 6, and 7) knawn as the
valve of Leiblein (Fretter & Graham,
1962). This organ consists of а pos-
teriorly directed cone-shaped protuberance
(Fig. 6, CP) that is enclosed in a chamber
formed by the expanded walls of the
anterior portion of the midesophagus
(Figs. 6 and 7). The inner surface of
the valve of Ге ет shows longitudinal
folds similar to these of the anterior
esophagus, with the exception that no
trace of the primitive dorsal folds or
midventral furrow can be found.

Histologically, the inner cone-shaped
papilla is lined with a continuation of the
ciliated simple columnar epithelium found
in the anterior esophagus. There are ro
muscle layers directly underlying this
epithelium. Confluent with this papilla
lies a ring of tall ciliated columnar epithe-
lial cells so disposed as to give the appear-
ance of a triangle in longitudinal section
(Fig. 7 and 15, RCC). _ These cells have
lightly-staining oval nuclei located cen-
trally. The cytoplasmic staining pro-
perties of these cells are distinctive. The
usual acid and basic counterstains fail
entirely to color the cytoplasm, and the
PAS reaction is also negative. In con-
trast, the cells exhibit strong metachro-
masia with toluidine blue, are colored by
the dialysed iron method for acid muco-
polysaccharides, and are heavily colored,
metachromatically, with methylene blue
below pH 2. The Alcian blue method
for acid mucopolysaccharides is com-
pletely ineffective in staining the cells.
however.

DIGESTIVE SYSTEM ОЕ NASSARIUS OBSOLETUS 455

РСС zn PsE
RE =

FIG.
FIG.
BIG:

FIG. 9.
Heidenhai

Siereogram cut-away view of the valve of Leiblein.

Sagittal section of valve of Leiblein. Heidenhain’s Azan.

Diagrammatic cross-section through valve of Leiblein at level x-x’ of figure 7.

Cross-section through portion of the salivary gland tissue showing ducts and secretory ductules.
n’s haematoxylin-Alcian blue.

456 STEPHEN C. BROWN

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 457

The adjacent thickened part of the
valve of Leiblein is composed of a pseu-
dostratified columnar epithelium which
bears cilia at its lumenal border (Fig. 7).
The cells making up this part are of 2
morphological types. The first type ex-
tends from basement membrane to lumen,
bears cilia, and has dense small nuclei
which are very uniformly located 1/5 of
the distance from the apical tip. The
other type extends from the basement
membrane to approximately 2/3 the height
of the tissue layer but does not reach the
lumen. The nuclei of the cells are scat-
tered in the basal 1/3 of the cytoplasm.
The cytoplasmic staining properties of
these cells are identical, but, like those
described above, differ from the typical
pattern. These cells orthochromatically
bind methylene blue below pH 2, and are
strongly stained by Alcian blue and the
dialysed iron reagent, indicative of acid
mucopolysaccharides. Contrary to the
above, however, these cells remain un-
stained after treatment with toluidine
blue. The pseudostratified layer grad-
ually diminishes in height and merges
into the simple columnar epithelium
lining the midesophagus.

The outer surface of the valve of Lei-
blein is covered with a thin coat of con-
nective tissue. There are only a few
muscle fibers found in the connective
tissue sheath and none arranged in an
orderly enough fashion to be termed a
true muscle layer.

Midesophagus: The midesophagus con-
tinues posteriorly from the valve of Lei-
blein and passes through the ring of
tissue formed by the ganglionic mass and

salivary glands. About half way along
its length, the midesophagus receives
along its mid-dorsal surface the duct from
the gland of Leiblein and then continues
rearward to the level to the columellar
muscle where an externally visible expan-
sion in tube diameter marks the begin-
ning of the postesophagus (Fig. 1). The
wall of the midesophagus shows an in-
crease in the number of folds over that
of the anterior esophagus, but there is no
trace of either dorsal folds or a specialised
channel leading into the gland of Leiblein
(Fig. 10).

The epithelium lining the midesophagus
is of a simple columnar type consisting of
three distinct cell types. The most pre-
valent are ciliated columnar cells with
subcentral, oval nuclei (Fig. 11, CCC).
These cells are similar to those found in
the anterior esophagus and, like them,
show an acidophilic character at their
bases yielding to basophilia at their
apices. These cells make up about 85%,
of the cell population. The next most
numerous type are mucous cells. These
cells have the typical goblet shape, being
narrow basally and expanding distally
(MGC). The nuclei of these cells are
dense and elongate and are located
basally. The cytoplasm immediately
surrounding the nuclei is acidophilic
while the mucin at the expanded tip of the
cells is a PAS-positive acid mucopoly-
saccharide (for histochemical characteri-
zation, see Table 1). The cells present
in the fewest numbers (са. 1%) are similar
in size and shape to the simple columnar
cells but differ from them in possessing
no cilia and in containing scattered

FIG. 10. Cross-section through the gland of Leiblein (above) and midesophagus (below). Heidenkain’s

Detail of wall of midesophagus, in cross-section. Heidenhain’s Azan.

Detail of septum of gland of Leiblein, in cross-section. Heidenhain’s haematcxylin.

Azan.

FIG. 11

FIG. 12

FIG. 13. Cross-section of post-esophagus. Heidenhain’s Azan.

458 STEPHEN C. BROWN

FIG. 14. Epithelium lining the midesophagus, showing cells containing mucoprotein granules. Heiden-
hain’s haematoxylin.

FIG. 15. Sagittal section through the valve of Leiblein in the area of the ring of ciliated cells. Weigert’s
iron haematoxylin-Orange G.

FIG. 16. Salivary duct at the level of the valve of Leiblein. Heidenhain’s haematoxylin.

FIG. 17. Secretory ductule of the salivary gland. Heidenhain’s haematoxylin.

throughout their cytoplasm small granules is shown, histochemically, by the facts
(Fig. 14, GC) which stain intensely with that they are PAS-positive, are strongly
acid dyes and Heidenhain's hematoxylin. stained by the coupled tetrazonium reac-

The glycoprotein nature of these granules tion for proteins, and that they have a

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 459

methylene blue extinction point in excess
of 6.

The heavy inner layer of longitudinal
muscle fibers surrounded by an outer
circular muscle coat (Figs. 10 and 11) is
identical with that of the anterior esopha-
gus. There are, however, no submucosal
gland cells present in the midesophagus.

Salivary glands: The pair of salivary
glands which superficially appear to be a
single entity form а horse-shoe-shaped
structure partially surrounding the dorsal
and lateral aspects of the midesophagus,
posterior to the valve of Leiblein and in
contact with the anterior surface of the
ganglionic ring (Fig. 1, SG). After care-
ful removal of the connective tissue
surrounding the glands, however, one
can Observe that the white lobular tissue
is divided into two discrete organs, each
with its own duct leading from the approxi-
mate center of its anterior surface, past
the valve of Leiblein, and into the pro-
boscis lateral to the anterior esophagus.

The glands themselves are of the acinar
type with small ductules ramifying through
the mass of tissue. Lining the ductules
is a layer of nonciliated columnar epithe-
lium usually only a single cell in depth
and composed of 3 morphologically dis-
tinct types of cells present in approxi-
mately equal numbers (Fig. 9). The
first type of cell (Fig. 9. М) generally has
a triangular shape with the base being
equal to the height of the cell. These
cells have round, lightly-staining nuclei
located subcentrally and are filled with a
mucin as indicated by the avidity witb
which they take up mucicarmine and
Bismark brown. Histochemical proce-
dures further indicate that this mucin is
a PAS-negative acid mucopolysaccharide
(see, Table (1); Phe 20а; type ‘об: cell
(Figs. 9 and 17 GC,) is usually of a more
typically columnar shape, although the
apical end is often expanded. These cells
have a round central nucleus with a single
prominent nucleolus and are filled with

large granules which stain very intensely
with azocarmine В and Heidenhain’s
hematoxylin. These granules are also
very intensely stained by the coupled
tetrazonium procedure for proteins, the
DMAB-nitrite reaction for tryptophan,
and the PAS technique, all indicative of a
glycoprotein composition. These granules
are identical in size and staining charac-
teristics with the granules found in the
salivary ducts. The cytoplasmic ground
substance of these cells fails to take up
either acid or basic dyes. The third type
of cell (Figs. 9 and 17; @С,) 15 struc-
turally similar to the preceding but differs
markedly in its staining properties. This
cell type shows more variation in the
intensity with which the structures are
stained than the previous type, but, in
general, the granules show less to much
less affinity towards hematoxylin and
azocarmine while the ground cytoplasm
exhibits strong to weak affinities for these
dyes. The same variation in intensity 15
to be seen with the histochemical stains,
the spherules being especially conspicuous
in never being colored as intensely as
those of type 2 cells. Within this varia-
tion, a consistent pattern can be observed
with regard to the relative staining inten-
sity of ground substance and granules.
In the majority of cases the 2 show an
equal affinity for the dyes, while the re-
maining cells of this type can be arranged
in a scale of decreasingly stained cyto-
plasm with a corresponding increase in
the intensity with which the granules are
colored (Fig. 9, GC,). Very probably
the variation observed in these cell types
is correlated with a differentiation of the
granules culminating in the definitive
cell type described as type 2.

Ciliated salivary ducts with a structure
identical to that described above are
found throughout the salivary glands.
These ducts often contain the ‘ntensely
staining granules and/or an amorphous
material with acid mucopolysaccharide

460 STEPHEN C. BROWN

staining characteristics (Mu). The glan-
dular tissue of the salivary glands is held
together by a thin matrix of connective
tissue. There are very few smooth muscle
fibers present.

Gland of Leiblein: The gland of Leı-
blein is a single, elongate organ which
lies immediately behind the salivary gland
/ganglion complex on the dorsal surface
of the midesophagus (Fig. 1, GL). This
tan to brown organ is connected at its
anterior end by a short duct to the mid-
dorsal surface of the midesophagus. The
gland tapers gradulally at its free posteror
end and slight lateral indentations are
observable along its length. Internally
the gland is of the monopodial branching
type and septa just inward laterally at
placieble corresponding to the externally
visible indentations. The spacious lumen
Fig. 10) is partially divided by these
septa while a conspicuous midventral
groove (Fig. 10, VG) bounded by a pair
of folds runs down the axis of the gland
and into the duct, eventually merging
with one of the grooves of the dorsal
wall of the midesophagus.

Histologically the septa are made of

thin connective tissue lamellae covered
with a pseudostratified columnar epithe-
lium so arranged that in cross section
they have а feather-like appearance
(Fig. 10, Sp). Two types of calls can be
seen lining the septal walls: granular and
mucous. The granular cells are of the
columnar type with basal oval nuclei
(Fig. 12, GC). The cytoplasm of these
cells is acidophilic at the base but has
little affinity for acid dyes at the cell
apex. The colorless tips of the cells are
usually expanded where they reach the
lumen and are filled with granules and
vacuolus of various sizes and shapes.
Next to the septa and indeed throughout
the lumen of the gland can be found what
are presumably nipped-off tips of these
cells (Figs. 10 and 12, GCF) containing
granules resulting from an apocrine type

of secretion of the granular septal cells.
Histochemical procedures indicate that
the granular contents of both the free
cell fragments and the tips of the septal
cells are principally mucoprotein (see
Table 1). The mucous cells (Fig. 12, М)
are of the typical goblet type, containing
a PAS-positive acid mucopolysaccharide,
and are scattered sparsely throughout the
septal walls.

The ventral folds are composed of a
ciliated simple columnar epithelium which
is reduced to a ciliated cuboidal epithe-
lium in the furrow of the ventral groove
(Fig. 10, VG). Interspersed with the
columnar cells are typical mucous goblet
cells containing a PAS-positive acid muco-
polysaccharide. Covering the entire gland
of Leiblein is a thin sheet of connective
tissue which is confluent with the lamellar
cores of the septa. Little if any muscle
Is present.

Postesophagus: The beginning of the
postesophagus is marked by an expansion
in the diameter of the tube. Accompany-
ing this, internally, the folds have made a
marked increase in depth, although the
number of folds remains approximately
the same (Fig. 13).

Histologically the epithelium lining the
lumen is identical to that of the mideso-
phagus. Here, again, ciliated columnar
cells predominate. Also present in small
numbers are goblet cells containing PAS-
positive acid mucopolysaccharide and
non-ciliated columnar cells containing
glycoprotein granules. A conspicuous
difference is found, however. in the sub-
epithelial structure. In contrast to the
heavy inner longitudinal and outer cir-
cular muscle layers found encasing the
midesophagus, only an extremely thin
layer of circular muscle fibers is found
surrounding the postesophagus (Fig. 13,
CM). In addition, only a small amount
of connective tissue is to be found beneath
the basement membrane underlying the
epithelium and the muscle layer.

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 461

Stomach: Viewed from the dorsal
aspect, the stomach has the shape of an
elongate tubular sac which assumes the
form of a semicircle as it spirals apically
with the rest of the visceral mass (Fig. 1).
The stomach is widest in girth at its
middle, where the postesophagus enters
vertrally, and then gradually tapers to a
bluntly rounded tip at the apical end.
The midgut glands closely envelop the
stomach except at the left dorso-lateral
surface (Fig. 1, AMG and PMG). The
expanded midpart of the stomach appro-
ximately corresponds with its internal
division into caecum (posterior) and style
sac (anterior). The caecum (Figs. |, and
18, C) is a cone-shaped bag at the anterior
edge of which the postesophagus empties
midventrally. The walls of the caecum
are thrown into numerous low folds
running longitudinally. Towards the left
side, just anterior to the opening of the
esophagus, lies an area of ciliated folds
converging on a smooth saddle-shaped
prominence (Fig. 18, SSA). To the right
of the esophageal opening lies a low,
longitudinally directed ridge, at either end
of which are located the openings to the
midgut glands (MO). Immediately to the
right of the low ridge lies a large area of
smooth epithelium along whose most
median edge there often lies a delicate
sheet of transparent cuticle, the gastric
shield (GS). This last-named structure,
when present, can easily be lifted in its
entirety from the underlying epithelium
and viewed separately. The gastric shield
of N. obsoletus is unusual in that it is
not found in all specimens. Those ani-
mals recently collected from the field
almost always have the shield present,
but they are absent from the majority of
animals maintained for any extensive
length of time in the laboratory on a diet
of frozen shrimp.

Just anterior to the above-mentioned
areas lies a deep transverse sulcus (LS)
which is in open communication with the

midventral longitudinally directed intes-
tinal groove (IG). Bounding this groove
on either side lie 2 large ciliated ridges,
the major and minor typhlosoles (Мат
and MiT). The minor typhlosole forms
the left border of the intestinal groove
and terminates anteriorly at the end of
the style sac where the first region of the
intestine makes an abrupt curve to the
right. Along the right side of the intes-
tinal groove runs the major typhlosole.
It is somewhat wider than the minor
typhlosole and instead of terminating at
the end of the style зас it continues into
the intestine, accompanying it through the
sigmoid curve before gently blending into
the intestinal wall.

In most animals recently collected from
the field. the style sac will be filled by a
gelatinous rod whose core may be filled
to a varying degree with sand particles
and algal detritus. This rod is the
crystalline style (CS). The style of Nas-
sarius (Fig. 24), when present, usually
extends the entire length of the style sac.
Anteriorly it tapers to a fine point, while
the other end, which extends rearward as
far as the gastric shield, is blunt or mush-
room-shaped and ofter has debris or a
ropy mucous string adherent to it. Like
the gastric shield, the crystalline style is
almost always present in those animals
examined in the field, but it is absent
from the majority of animals maintained
for any extensive length of time in the
laboratory on a diet of frozen shrimp.
Laboratory animals which are not fed
shrimp but have access to algal scum
almost always possess both shield and
style.

Histologically, the lining of the caecum
contains mucous goblet cells (Fig. 21,
MGC) and granule-filled nonciliated
columnar cells (NCE) structurally and
histochemically identical with their coun-
terparts in the mid- and postesophagus
(see also Table 1). The predominent cell
type is of the simple columnar variety,

462 STEPHEN C. BROWN

FIG. 18. Interior view of stomach (caecum and style sac), opened by a dorsal longitudinal incision and
laid back slightly. Arrows indicate ciliary currents discussed in text.

FIG. 19. ‘Relationship of stomach to visceral mass, diagrammatic. A. Stomach and midgut glands,
viewed dorsally. B.-E. Sections through levels a-a’ to d-d’, respectively.

FIG. 20. Cross-section through visceral mass at the mid-region of the style sac. Heidenhain’s Azan.

‘FIG. 21. Detail of wall of caecum, in cross-section, Heidenhain’s haematoxylin,

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS

FIG. 22. Vinyl acetate injection showing a side
view of the branching ductwork of the midgut
glands. Most of the stomach region has been cut
away for clarity.

FIG. 23. Vinyl acetate injection showing in more
detail a top view of the secondary duct system
indicated in Fig. 22.

FIG. 24. A crystalline style
removed from the style sac of
Nassarius obsoletus.

464

STEPHEN C. BROWN

TABLE 1. Histochemical affinities of various components of the digestive system.

Coupled
Tetra-
zonium

Buccal cavity
subepith. mucous
cells
Ant. esophagus
subepith. mucous
cells
Midesophagus
epithelial mucous
cells
granular cells
Postesophagus
epithelial mucous
cells
granular cells
Salivary glands
Type | granular
cells
Type 2 granular
cells
Mucous cells
Valve of Leiblein
“Ring” cells
Pseudostratified
layer
Gland of Leiblein
Granular septal
cells
Free granular cell
fragments
Septal mucous
cells
Mucous cells of
ventr. groove
Midgut gland
Triangular cells
Mucous cells
Caecum
Epithelial mucous
cells
Granular cells
Style sac
Major typhlosole
Minor typhlosole
Epithelial mucous
cells

| | | Tolui- Methy-
| | dine | Hyalu- | lene
DMAB- PAS | Dias- | Blue roni- Blue Alcian
Nitrite | {азе y-meta- dase Extinc- Blue
| | chro- tion
| таза point
—— | —-
|
— fast ma fast <2 +
- fast fast D) +
| | | |
— fast a fast <2 +
— fast + >6 —
— | fast + fast = 27 Ser
|
= fast = 6
fast — >6 — |
|
|
+ fast — >6 —
— — fast <2 ae
— — fast de
= == =) 4
— fast = >6 —
— fast — >6 —
- fast fast 2 +
— fast + fast << De +
— fast fast = =
- fast 4 fast 29) +
= fast — >6 —
nn re fast — 2-3.5 —
— | == — ==
— | fast fast <a) —-

Dia-
lysed
Iron

DIGESTIVE SYSTEM OF

TABLE 1.—(contd.)

NASSARIUS OBSOLETUS

465

| | | |
| | | | Tolui- | Methy- | |
¡Goupled| | | | dine | Hyalu- lene | | Dia-
Tetra- | DAMB- PAS | Dias- | Blue | roni- Blue | Alcian | lysed
| zonium | Nitrite | tase {y-meta-| dase | Extinc- Blue | Iron
| | | chro- tion | |
| таза | point |
—— = —— Te === = 7 = 5 Te —
Crystalline style | + A fast | | fast | 23,5
Gastric shield — fast - 2-3.5 | — —
Intestine (1) |
Epithelial mucous — — — | fast 2
cells | |
Intestine (2) |
Epithelial mucous — — — | fast | р |
cells | | | |
Rectum | | | | |
Epithelial mucous | — | — | — | а 2 | lus
cells | | | | |
| | | | |
lacking the conspicuous granules. This plasm exhibits a moderate uniform acido-
type of cell in the caecum differs from philia. The epithelium of the intestinal

those in the esophagus, however, in being
devoid of cilia. The subepithelial tissue
structure more closely resembles that of
the postesophagus than that of the mid-
esophagus. Underlying the basement
membrane immediately below the epithe-
lium is an area composed of connective
tissue with a small amount of irregularly
oriented muscle fibers (CT). In this area
also are to be found numerous hemocytes.
These blood cells have never been ob.
served in the lumen of the caecum or
between the cells of the lining epithelium.
Beneath the layer of connective tissue a
very heavy layer of circular muscle fibers
(CM) envelops the entire caecum. No
longitudinal muscle layer is present.

The lining of the style sac region of the
stomach stands in sharp contrast to that
of the caecum. The minor typhlosole
(Fig. 20, MiT) and roof of the stomach
are composed of a layer of ciliated simple
columnar epithelium. The oval nuclei
are uniformly located 1/3 of the distance
from the base of the cells, and the cyto-

groove (IG) consists mainly of a similar
ciliated columnar epithelium which on the
floor of the groove shortens to an almost
cuboidal shape. In addition, goblet cells
containing a PAS-positive acid muco-
polysaccharide are scattered throughout
the sides and floor of the groove. The
epithelium of the major typhlosole (MaT)
is conspicuous, being entirely made up of
much taller, exceedingly thin ciliated cells.
These cells also differ in having elongate
very dense nuclei and, perhaps most note-
worthy, a cytoplasm exhibiting pro-
nounced basophilia. Histochemical tests
indicate that the cytoplasm of these cells
contains copious amounts of glycopro-
tein. This glycoprotein is more or less
evenly distributed throughout the cells
and is not confined to discrete granules.
Underlying the lining epithelium of the
style sac is a thick layer of loose connec-
tive tissue containing numerous hemo-
cytes, a few irregularly arranged muscle
fibers, and blood vessels (Fig. 20). Also
lying in this loose connective tissue be-

466 STEPHEN C. BROWN

и Ри %
Ss IN
e

121418
№, 3
id Se Ge
SS EN EN
dr я > 1504
A Z ae A UE m E e E
ESS 7

ai = Ir
7 nr N я he 7
ss = A Zelle one as u ma MGC

FIG. 25. Section through portion of midgut gland tissue. Heidenhain’s Azan.
FIG. 26. Detail of midgut gland tubule. Epon, Azure B bromide.
FIG. 27. Cross-section through proximal region of intestine. Heidenhain’s Azan.

FIG. 28, Cross-section through the distal region of the intestine, Heidenhain’s Azan,

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS _ 467

tween style sac and midgut gland are two
aggregations of large cells with basal
nuclei which .contain large amounts of
calcium within them. Indeed, these are
the only sites in the visceral mass of the
snail which contain calcium in sufficient
amounts to be avidly stained by Nuclear
fast red.

Midgut glands: The 2 midgut glands
constitute the greatest bulk of the visceral
mass (Fig. |, AMG, PMG). The ante-
rior gland forms a cradle ventral and
lateral to the style sac, starting appro-
ximately at the level of the anterior duct
into the stomach and proceeding ante-
riorly to the region of the sigmoid curve
of the intestine. The posterior gland
begins at its duct into the stomach ante-
riorly. accompanies the caecum оп its
right ventrolateral border, and continues
spiraling toward the apex of the shell
along with the gonad. The midgut glands
have an acinar structure and are рег-
meated by a tree-like network of ducts
(Figs. 22 and 23).

In cross sections of the visceral mass,
the tubules of the midgut glands are cut
in both cross and longitudinal sections.
There are 4 types of cells distinguishable
in the midgut gland tubules. First, there
are mucous cells, containing a PAS-posi-
tive acid mucopolysaccharide, present in
very small numbers (less than 1%) scat-
tered at random within the tubules. A
2nd type of cell is present at the angles
of the tubules. These cells are usually of
a triangular shape with a large subcentral
nucleus containing a prominent nucleolus
(Figs. 25 and 26, TC). The cytoplasm is
highly vacuolated and slightly, but uni-
formly, acidophilic. This cell type, in
addition. becomes stained throughout the
cytoplasm by the DMAB-nitrite technique
for tryptophan. Scattered within the
apical 3/4 of the cytoplasm are small
yellow refractile inclusions (RI) which do
not take up the usual cytoplasmic dyes.
The apical cytoplasm normally bulges

slightly into the lumen of the tubule.

The cell type most prevalent (approxi-
mately 85%) is a simple columnar cell
with an oval nucleus located uniformly
1/3 of the distance from the base of the
cells (125. 25 and 26, СС). us cell
type has a frothy appearance subapically,
the cytoplasm being acidophilic through-
out most of the cell but becoming lightly
basophilic at the luminal edge. The
prussian blue staining technique indicates
the presence of iron scattered throughout
the cytoplasm. The apex of the cell is
covered with short microvilli which were
clearly visible only in Epon sections. The
fourth cell class is very similar to the
preceding, except that the apex of the cell
dilates into the lumen of the tubule and
is devoid of microvilli (CC,). Nearly the
entire apical expansion is strongly baso-
philic. The latter 2 cell types in all
probability represent activity stages of a
single class of cells. Nothing resembling
food vacuoles could be found in these
cells, either in animals which had just
been taken from the field or in animals
which had been maintained on any of the
experimental diets.

Between the ramifying tubules of the
midgut gland loose connective tissue,
blood vessels, numerous hemocytes, and
aggregations of dark brown to black
pigment granules are present (Figs. 20
and 25).

Intestine: Proceeding anteriorly from
the style sac, the intestine goes but a
short way before taking a sharp right-
hand bend which signals the beginning of
the transverse sigmoid curve (Fig. 1).
This curving portion of the intestine
crosses the visceral mass just posterior to
the kidney and forms the forward boun-
dary of the anterior midgut gland. After
completing the sigmoid curve, the intes-
tine arches dorsally within the right side
of the mantle tissue.

The intestine can be divided, histo-
logically, into two distinct parts which

468 STEPHEN C. BROWN

roughly correspond to the sigmoid por-
tion and to the dorsally arching segment.
The first part of the intestine (Fig. 27)
has its walls thrown into longitudinal
folds similar to the esophagus. Unlike
the esophagus, however, the first part of
the intestine possesses a large shelf-like
typhlosole along its right wall (Fig. 27,
Ty). This typhlosole is a continuation of
the major typhlosole found in the style
sac but is histologically very distinct from
the latter. The epithelium lining the
lumen of the intestine is of a simple
columnar type consisting of 2 classes of
cells: ciliated columnar cells (CCC) and
mucous goblet cells (MGC). The ciliated
cells are identical to their counterparts in
the esophagus. The mucous cells con-
tain a PAS-negative acid mucopolysac-
charide with a methylene blue extinction
point far below any other mucin observed.
The mucous goblet cells show a great
increase in number over those found in
the esophageal regions, comprising approx-
imately 35%, of the cells lining the lumen
of the intestine. The mucous cells of the
intestinal region also show a distribution
different from that found in the eso-
phagus. In the esophagus and along the
typhlosole of the first part of the intestire
the mucous cells are distributed essen-
tially at random. Along the folded walls
of the intestine, in contrast, the mucous
goblet cells are conspicuously confined to
the regions of the furrows and are not to
be found along the projecting folds.
Underlying the basement membrane be-
neath the epithelium, a heavy layer of
longitudinal muscle fibers surrounds the
first part of the intestine (Fig. 27, LM).
These longitudinal muscles are confined
to the areas of folded epithelium and are
not present in the typhlosole. Outside
this layer of longitudinal fibers is a layer
of circular muscle fibers which encases
the entire intestinal tube and penetrates
the typhlosolar fold, ultimately coming
to lie directly beneath the basement mem-

brane in this region (СМ).

The longitudinal folds are continued in
the second portion of the intestine: the
typhlosole, however, is not present. The
types and distribution of cells lining the
lumen are identical with the preceding
part of the intestine. The subepithelial
Structure of this part of the intestine
differs markedly from the first part in
that there is no longitudinal muscle layer
underneath the lining epithelium, al-
though a strongly developed circular
muscle layer is present (Fig. 28, CM).

Rectum: The intestine terminates in a
short papilla which projects freely inte
the pallial cavity from the right side of
the mantle roof. Histologically the
rectum is identical with the latter portion
of the intestine.

3. Evaluation of Data

Among the described species of Nas-
sarius. the general anatomical and histo-
logical features of the digestive systems
are similar (see Fretter & Graham, 1962,
for N. reticulatus; Martoja, 1964, for N.
reticulatus, N. corniculum, and N. incras-
satus; Dimon, 1905: and this study for
N. obsoletus). The following discussion
summarizes some of the salient anato-
mical and histological characteristics of
the digestive system of Nassarius obsoletus
in particular, and of the Nassariidae in
general.

One of the striking, easily observable,
features of N. obsoletus is the extreme
length of the extended proboscis (Figs. 1
and 36). This highly-developed probos-
cis is characteristic of all the rachiglossan
Neogastropoda (Pelseneer, 1906) and is
correlated with their usually carnivorous
habit (Blegvad, quoted in Yonge, 1954:
Fretter & Graham, 1962: and Martoja,
1964). Although not previously consi-
dered in the present studv, the radular
dentition of N. obsoletus (figured by
Dimon, 1905, p 50) shows the typical
rachiglossan pattern of 1+R+1 which

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 469

is well-adapted for the tearing and rasp-
ing of soft material such as flesh.

The solid cuticular thickenings
(=“ jaws” or “ mandibles’) found at
the anterior end of the buccal cavity of
toxoglossan and some rachiglossan neo-
gastropods (Pelseneer, 1906: Hyman,
1967) are absent in N. obsoletus and
apparently the other species of Nassarius
studied. The buccal cavity of N. obso-
letus also differs from the condition found
in most other gastropods (Fretter &
Graham, 1962) in possessing as the only
mucous cells of the lining of this cavity,
large flask-shaped gland cells located
beneath the longitudinal muscle layer,
rather than having the more typical
goblet-type cells confined entirely to the
epithelial layer.

These subepithelial mucous cells con-
tinue the length of the anterior esophagus
and, as in the buccal cavity, they are the
only type of secretory cell found in the
lining tissue. The rest of the esophageal
tube is characterized by the presence of
goblet-type mucous cells in the lining
epithelium. The anterior esophagus fur-
ther differs from the rest of the esophagus
by the absence of cells containing glyco-
protein granules. In addition, as men-
tioned above, the only remnants of the
primitive dorsal folds and food channel
(Graham, 1939) to be found in N. obso-
letus are in the anterior esophagus. A
further notable feature of the anterior
esophagus (and indeed of the esophagus
in general) is that though it bears cilia
along the entire lining surface, it possesses
a very well-developed subepithelial mus-
cle coat. This fact is in accord with
observations made in the present study
(see part 4) and earlier by Jenner (1956b)
that peristalsis plays an important part in
moving food along the alimentary
canal.

Correlated with the extensive develop-
ment of the rachiglossan proboscis is
the presence of the valve of Leiblein.

As Graham has emphasized (1941), it
performs the extremely important func-
tion of preventing food from returning
to the anterior esophagus in animals
which continuously elongate and contract
the anterior end of their alimentary canal
during feeding. Fretter & Graham
(1962, p 217) state that among the rachi-
glossan gastropods, “. . . in the Bucci-
nacea the valve of Leiblein is reduced or
even absent (Galeodes, Semifusus, Busy-
con)”. The Nassariidae. apparently,
form a consistent exception to this, for
in N. obsoletus and all the other species
of Nassarius illustrated. a well-developed
valve of Leiblein is present (Fretter &
Graham, 1962; Martoja, 1964).

The salivary glands and ducts also show
the effects of the elaboration of the pro-
boscis. In the Nassariidae, as in the rest
of the Stenoglossa, the differential growth
of the anterior part of the gut has
“ pulled ” the salivary glands and ducts
“through ” the nerve ring. the salivary
glands thereby assuming a position in
front of the cerebral commissure and the
salivary ducts thus becoming free of any
restraint imposed by the nerve ring
(Fretter & Graham, 1962). The cell
composition of the salivary gland tubules
appears identical in the three species of
Nassarius which have been studied in
this respect (Fretter & Graham, 1962;
Martoja, 1964). The mucous secretion
presumably aids in lubrication of the
radular apparatus during feeding; the
function of the glycoprotein granules is
not clear. Basic protein secretory pro-
ducts are of widespread occurrence in the
saliva of snails (Fretter & Graham, 1962),
and in several species the presence of
enzymatic activity associated with the
Salivary glands has been shown (pro-
teases in Murex by Hirsch, 1915, and by
Mansour-Bek, 1934; amylase in Littorina
by Jenkins, cited in Fretter & Graham,
1962; and disaccharases in Nassarius
obsoletus, this study, part 3). Whether

470 STEPHEN С. BROWN

the proteinaceous granules are the source
of the enzymatic activity remains to be
shown. From the histological structure
of the salivary glands and ducts it would
appear that secretory pressure 1$ respon-
sible for moving the granules and mucus
from the glandular tubules into the sali-
vary ducts. at which point ciliary action
conveys the secretory products distally to
the buccal cavity. The circular muscles
at the termina! ends of the salivary ducts
presumably act as sphincters in helping
to regulate the flow into the buccal
cavity.

As shown by Graham (1941) and re-
viewed by Fretter & Graham (1962), the
elongation of the proboscis in the Rachi-
glossa has been further accompanied by
a “stripping off” of the glandular area
associated with the midesophagus, result-
ing in the formation of a discrete organ,
the gland of Leiblein, whose only contact
with the parent midesophagus is by the
duct emptying into it. Presumably. there-
fore, this duct from the gland of Leiblein
marks the most posterior extent of the
“ pre-stripped ” midesophagus (Graham,
1941). From the histological evidence,
however, this appears not to be the case
in N. obsoletus. As described above, a
well-defined structural change occurs in
the esophageal region some distance
posterior to the duct from the gland of
Leiblein, at the level of the columellar
muscle.

That functional activity has been re-
tained by the gland of Leiblein regardless
of anatomical shifting is attested to by
the conspicuous apocrine secretions re-
ported for these glands in rachiglossans
in general and in N. reticulatus (Martoja,
1964) and N. obsoletus (this study) in
particular. Further evidence for a func-
tional role for the gland of Leiblein is
given by the repeated demonstration of
digestive enzyme activity in its secretion
(Hirsch, 1915: Mansour-Bek, 1934: Brock,
1936; this paper part 3).

The stomach of N. obsoletus is com-
parable with those of other rachiglossans
in the assumption of a sac-like shape, in
showing a migration of the esophageal
opening posteriorly, and in the reduction
of ciliary sorting fields to a minimum
(for illustrations of other rachiglossan
stomachs, see Graham, 1949, Morton,
1958b: Fretter & Graham, 1962: Martoja,
1964: and Wu, 1965). The caecum of
N. obsoletus is apparently unique among
the Nassariidae in lacking ciliation. The
deep longitudinal folding undoubtedly
serves the mechanical function of allow-
ing a great deal of expansion when the
snail has ingested food, thereby permit-
ting the caecum to serve as a temporary
storage organ for this material. The
underlying heavy circular musculature is
then responsible for moving the food
mass anteriorly into the style sac region
of the stomach.

The possession of a _ gastric shield,
regarded as a primitive character in the
Gastropoda, has been confirmed for all
the species of Nassarius studied in detail
(Graham, 1949: Martoja, 1964: and the
present study). and for a related species,
Cyclope neritea (Morton. 1958b). The
production of a crystalline style in the
“* carnivorous ” Stenoglossa is incom-
patible with the principal that “ a crystal-
line style and the carnivorous habit
cannot normally co-exist ” (Yonge, 1930).
Although neither Martoja (1964) nor
Graham (1949) report the presence of
styles in the Nassariidae studied by them,
styles are definitely present in Cyclape
neritea and Nassarius obsoletus. Whether
or not these styles are truly functional
(i.e., as repositories of enzymes) or merely
neomorphic protostyles derived from food
string aggregations, is not known for
Cyclope. but it has been shown
(this study. part 3) that styles of N.
obsoletus do indeed exhibit enzymatic
activity.

With regard to the cellular composition

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 471

of the midgut glands, it is apparent that
the histology of the midgut gland varies
considerably from animal to animal
amongst the prosobranchs (Fretter &
Graham. 1962). The types and structure
of midgut gland cells herein described for
N. obsoletus are in good agreement with
those described by Martoja (1964) for the
European species of Nassarius. Little
attempt will be made here to relate the
cell types found in N. obsoletus with
those found in the rest of the Gastro-

poda. The difficulties and pitfalls of

synonymy for even a single genus are
well illustrated in Sumner’s thorough
review (1965) of the midgut gland cells
of Helix. Nevertheless, the triangular
cells of N. obsoletus agree well with the
“* cellules coniques ” of Martoja (and, in
general, with the “ secretory cells ” of
Fretter & Graham) and the columnar
cells (types. (Of phases, 1 ава 2)
with Martoja's “* cellules cylindriques ”
(and Fretter & Graham's “ digestive
cells).

The intestine, as previously shown, is
characterized by a regional differentiation
due to the presence or absence of a typh-
losole and to differences in the subepithe-
lial muscle coat. A great increase in the
number of mucous cells in the intestine
as compared with the esophagus is also а
conspicuous feature. The latter 2 char-
acteristics, in particular, are undoubtedly
correlated with consolidation of the feces
and movement of material through the
intestinal lumen (see further discussion of
this below, in part ГУ and general dis-
cussion).

In view of Martoja’s conclusion (1964)
that the amoebocytes of the European
species of Nassarius play a very important
role in the digestion of food, it is note-
worthy that in N. obsoletus no histological
evidence could be observed that the amo-
ebocytes (hemocytes) were ever present
withir the lumen of the gut or even
between the epithelial cells lining the

various regions of the alimentary canal.

Finally, the digestive tract of N. obso-
letus, like those of all gastropods, is
characterized by the abundance of mucus-
secreting cells. The functional correlates
of this are well-known and understood
(Morton, 1958: Fretter & Graham, 1962;
for reviews and extensive bibliographies).
investigations (principally histochemical)
on the diversity of mucin types in mol-
luscs are still in their infancy. Those
studies which have been made (for exam-
ple by Martoja. 1964, on the digestive
systems of certain of the Nassariidae, and
by Smith, 1965, on the reproductive tract
of the slug Arion ater) indicate that great
diversity and regionai differentiation of
mucin types is the rule. even within a
single organ system. The following histo-
chemically-detected classes of mucins are
conspicuousiy present in the digestive
system of Nassarius ohsoletus: (1) PAS-
positive acid mucopolysaccharides of epi-
thelial goblet cells: in midesophagus.
postesophagus, ventral groove of gland
of Leiblein, septal cells of gland of Lei-
blein, caecum, midgut gland, and ventral
groove of style sac: (2) PAS-positive acid
mucopolysaccharides of subepithelial uni-
cellular gland cells: in buccal cavity and
anterior esophagus: (3) PAS-negative
acid mucopolysaccharides of epithelic|
goblet cells: in Ist and 2nd part of the
intestine and rectum; (4) PAS-negative
acid mucopolysaccharides in gland cells
of salivary tubules: (5) DMAB-nitrite
positive glycoproteins in gland cells of
Salivary tubules; (6) DMAB-nitrite nega-
tive glycoproteins in epithelial columnar
cells: in midesophagus. postesophagus,
and caecum: (7) Histochemically proble-
matical mucins in valve of Leiblein: and
(8) glvcoprotein/acid mucopolysaccharide
material of the crystalline style. Thus,
the present histochemical study adds
further evidence for the preponderance
of mucin heterogeneity in gastropod
organ systems.

472 STEPHEN C. BROWN

Ш. ENZYME HISTOCHEMISTRY
|. Materials and methods

All animals used in this part of the
study had been maintained at the Univer-
sity of Michigan in sea-water aquaria
prior to fixation. Tissues were quick-
frozen by quenching in isopentane cooled
by liquid nitrogen and then sectioned at
8-12 microns on an International model
CT cryostat equipped with a razor blade
holder. Fixation, either before or after
sectioning, was carried out in Lillie’s
buffered neutral formalin at 4°C for
| hour.

Acid phosphatase: Two methods were
employed for the detection of this enzyme.
The first was Gomori’s lead nitrate
method (Gomori, 1950) on post-fixed
material with sodium P-elycerophosphate
as substrate. The other was the simul-
taneous azo dye method (Barka & Ander-
son, 1963) on prefixed material. In this
method, sodium «-naphthyl acid phos-
phate was the substrate and _ freshly
diazotized pararosanilin was used as
coupler. The reaction was carried out
at room temperature in barbiturate buffer
(pH 6°0). Results from both Gomori
and simultaneous coupling techniques
were in complete agreement.

Alkaline phosphatase: As in the pre-
ceding case, 2 different methods were
employed. These were the Gomori (1952)
calcium-cobalt method and the simulta-
neous coupling technique as given in
Barka & Anderson (1963). In the former.
sodium-f-glycerophosphate was used as
substrate on post-fixed tissue. Sodium
a-naphthyl acid phosphate was employed
as substrate in the latter, with Fast red
TR as diazo coupler. This reaction was
carried out on prefixed material at pH 9:2
in barbiturate buffer. As before, results
obtained from the Gomori and simul-
taneous coupling methods were in agree-
ment.

Esterase: The indoxyl acetate method

for nonspecific esterases was employed,
according to the method of Holt &
Withers (1952) and Holt (1958). Prefixed
tissue sections were incubated at 37°C.
in O-acetyl-5-bromoindoxyl. The incu-
bating medium was maintained at pH 6:5
with tris (hydroxymethyl) aminomethane
buffer, and the enzyme activity was ren-
dered visible by the formation of insoluble
indigo with ferricyanide-ferrocyanide as
the redox pair.

Cathepsin C: This method, developed
by Hess & Pearse (1958), utilizes indoxyl
acetates as substrate (O-acetyl-5-bromoin-
doxyl was used in the present study).
The indoxyl liberated by enxymatic hydro-
lysis is converted, as in the previous
method, to indigo by ferricyanide-ferro-
cyanide oxidation. The specificity for
cathepsin C is achieved by preincubation
of all sections in E-600 (diethyl-p-nitro-
phenyl phosphate) which inactivates all
B-type esterases present in the tissues,
Sections subsequently incubated in activa-
tor (1х10-3М cysteine) and inhibitcr
(1 х 10-3М lead nitrate) are compared
with control sections, and any cell, сог-
taining indigo in the control section,
which contains more indigo after incuba-
tion with the activator and less after the
use of the inhibitor, is considered to
exhibit esterase activity of the type asso-
ciated with cathepsin C.

Leucine Amino Peptidase: The simul-
taneous coupling method of Nachlas,
et al. (1957) using L-leucyl-B-napthyl
amide as substrate was employed. The
coupler used was Fast blue B salt and
the reaction was carried out in acetate
buffer (pH 6°5) at 37°C.

Beta-glucuronidase: This enzyme was
detected by the post-coupling method of
Seligman, et al. (1954). The synthetic
substrate used was 6-bromo-2-naphthy!-
B-D-glucuronide. Sections were incu-
bated in phosphate-citrate buffer (pH 4 9)
at 37°C. and Fast blue B salt was used
as the diazo coupler.

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 473

Gomori’s Tween method for lipase
(Pearse, 1960), using Tween 80 (poly-
oxyethylene sorbitan monooleate) as sub-
strate, was performed on the various
tissues, but was eventually abandoned
because only patchily-distributed non-
specific staining could be obtained. Post-
coupling techniques for £-glucosidase and
8-galactosidase (Rutenberg, ef al, 1958)
using 6-bromo-2-naphthyl glycosides were
likewise abandoned because of failure to
achieve consistent results.

Sections incubated in medium lacking
substrate and pre-incubation of sections
in water at 95°C for 5 minutes were used
as controls for all staining procedures.

2. Results

Buccal cavity: The only enzyme demon-
strable in the buccal cavity was a non-
specific esterase. Enzyme activity was
present in the entire lining epithelial layer,
although it was not localized identically
in every cell. All cells exhibited enzyme
activity at their apical regions. while more
basal activity varied among the cells
from none at all to complete and even
distribution throughout the entire cyto-
plasm.

Anterior esophagus: Enzymes demon-
strable in the anterior esophagus included
acid phosphatase, esterase. and leucine
amino peptidase. The acid phosphatase
activity was confined to the apices of the
cells lining the lumen of this region. The
non-particulate homogeneous reaction
product formed a distinct continuous
band immediately beneath the cilia. No
particulate reaction sites in the cytoplasm
of these cells were observed. Esterase
activity was scattered along the epithe-
lium, rather than exhibiting the con-
tinuity observable in the buccal cavity
epithelium. The cellular distribution,
however, was similar to that found in
the buccal cavity epithelial cells—being
present apically in all the cells exhibiting
activity, but varying to the extent to

which it extended into the basal cyto-
plasm. Leucine amino peptidase activity
was found in all cells in the epithelial
lining. Activity was confined to the
distal 2/3 of the cells and the reaction
product was present as a homogeneous
precipitate throughout this area.

Midesophagus: Enzymes demonstrable
in the midesonhagus include acid phos-
phatase, alkaline phosphatase, esterase,
and leucine amino peptidase. The reac-
tion product of acid phosphatase activity
was confined to a thin homogeneous
layer at the luminal border of the epithe-
lium, as in the anterior esophagus. Alka-
line phosphatase activity was similarly
localized along the margin of the lining
epithelial cell layer. In both, no activity
was observed deeper within the cell cyto-
plasm. Esterase activity was again scat-
tered throughout the epithelial lining and
intracellular localization was varied, as
before. Leucine amino peptidase activity
was present homogeneously throughout
the apical 2/3 of the cells lining the
midesophagus.

Postesophagus: Enzymes present in the
postesophageal epithelium included acid
phosphatase, alkaline phosphatase. and
esterase. The distribution of these en-
zymes in the lining epithelial cells was
identical to that described above.

Valve of Leiblein: The only enzyme
demonstrable in the valve of Leiblein was
acid phosphatase. The sites of localiza-
tion were in the ciliated columnar epithe-
lial cells which are directly continuous
with the lining epithelia of the anterior
and midesophagus, and in the cells which
make up the “ring” surrounding the
cone-shaped papilla. Activity in the cili-
ated cells was confined, as before, to the
luminal border. In the cells of the
“ring”, however, the reaction product
was deposited homogeneously through-
out the entire cytoplasm. No enzyme
activity was observed in the pseudostrati-
fied portion of the valve of Leiblein.

474 | STEPHEN С. BROWN

Gland of Leiblein: Enzymatic activity
in the gland of Leiblein was demonstrable
for alkaline phosphatase, acid phospha-
tase, and leucine amino peptidase. Acid
and alkaline phosphatase activity was
present in some, but not all. of the septal
cells. In those cells in which activity
was found, the reaction product was con-
fined to the apical borders of the cells.
Very strong leucine amino peptidase
activity was present in all the septal cells.
The reaction product was deposited homo-

geneously throughout the cytoplasm of

these cells and not restricted to a parti-
cular portion of them.

Salivary glands: No enzymatic activity
could be demonstrated by any of the
histochemical techniques employed.

Caecum: Enzymes detectable in the
‘epithelium lining the caecum inciuded
acid phosphatase, alkaline phosphatase,
and esterase. Lecalization of these en-
zymes was identical to that of the post-
esophagus.

Style sac: Alkaline phosphatase, acid
phosphatase, and esterase were demor-
strable in the epithelium lining the style
sac. The distribution of phosphatase
activity was as follows: a very thin homo-
geneous band of activity appeared at the
luminal border along the roof of the style
sac; contrasting sharply with this at the
regions of the minor typhlosole and
ventral groove was a thick band of much
greater activity which extended below the
apices of the cells into the cytoplasm.
The reaction product deposited in this
thick band of enzyme activity was also
homogeneous. No activity could be
detected in the basal cytoplasm of these
cells. In the cells covering the major
typhlosole, no phosphatase activity what-
soever could be demonstrated. Esterase
activity was confined to the regions of the
roof of the style sac, the minor typhlosole,
and the ventral groove.

Midgut gland: Enzymes demonstrable in
the midgut gland included alkaline phos-

phatase, acid phosphatase, esterase.
cathapsin С, and £-glucuronidase. leu-
cine amino peptidase activity could not
be detected. Phosphatase activity, as in
the previous tissues, was confined to a
thin band on the luminal border of the
midgut gland tubules (Figs. 30 and 31).
Not all cells gave the reaction, but appa-
rently there was no strict correlation with
cell type, as both the triangular cells and
the columnar cells exhibited activity.
Strong esterase activity was shown by the
cells of the midgut gland tubules. This
activity was spread throughout the cyto-
plasm (Fig. 32). Beta-glucuronidase
activity was found throughout the cells
of the midgut gland tubules. Cathepsin
C activity was found scattered throughout
the epithelial lining of the tubules. This
enzyme was apparently confined to the
columnar cells, being most noticeable in
type 2 cells which bulge into the lumina
of the ducts. The intracellular localiza-
tion was homogeneous throughout the
cytoplasm of the cells.

Intestine: In both regions of the intes-
tine, acid phosphatase, alkaline phospha-
tase, and esterase could be demonstrated.
The activity and distribution of these
enzymes was essentially identical to that
found in the caecum and _ esophagus.
Additionally, in the second part of the
intestine, leucine amino peptidase could
be detected in the epithelial lining. Activ-
ity of this enzyme was spread throughout
the apical 2/3 of the cells.

Rectum: In the rectum, no enzymatic
activity could be detected by any of the
techniques employed.

3. Evaluation of data

Although a large literature has accu-
mulated on the histochemical localization
of hydrolytic enzymes (principally in
vertebrate tissues), the biological signi-
ficance (or functional role) correlated with
the observed enzymatic distribution is in
most cases not well known. Few specific

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 475

FIG. 29. Subepithelial mucous gland cell within wall of buccal cavity. PAS technique.

FIG. 30. Midgut gland tubules showing a heavy deposit of acid phosphatase reaction product along
the lumenal borders. Gomori lead nitrate method with Mayer’s haemalum counterstain.

FIG. 31. Cross-section of single midgut gland tubule showing acid phosphatase localization confined
to cell apices. Simultaneous coupling method, no counterstain.

FIG. 32. Midgut gland tubules showing strong esterase activity throughout the cells. Indoxyl acetate
method.

conclusions, therefore, can be drawn con- The presence of alkaline phosphatase
cerning the histochemical data just pre- along the free cell borders of the epithelia
sented (see Table 2 for tabulated results). in Nassarius obsoletus is consistent with

476 STEPHEN ТС:

BROWN

TABLE 2. Enzyme histochemistry of various components of the digestive system.

Acid Alkaline
phosphatase phosphatase

ESTAS,

Buccal cavity
Epithelial cells

Ant. esophagus
Epithelial cells N LE

Midesophagus
Epithelial cells

Postesophagus
Epithelial cells

Salivary glands
Granule cells = Be

Valve of Leiblein
`` Ring ” cells —
Epithelial cells -

Gland of Leiblein
Septal cells

Midgut gland
Columnar cells
Haemocytes == =

Саесит
Epithelial cells

Style sac
Roof epithellium
Major typhlosole — —
Minor typhlosole
Ventral groove

Intestine (1)
Epithelial cells

Intestine (2)
Epithelial cells

Rectum
Epithelial cells = =

the localization found in many vertebrate
tissues. Although clear-cut evidence of
a specific functional role is lacking for
alkaline phosphatase, the nearly universal

Esterase С

Leucine
amino
peptidase

Cathepsin B-Glucu-
ronidase

association of this enzyme with especially
active ceil surfaces (such as those posses-
sing microvilli) is taken to indicate that
it participates in the movement of mole-

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 477

cules across the cell membrane (Rothstein,
en al, 1953).

The membrane-associated acid phos-
phatase and non-specific esterase likewise
are thought to act in the transport of
material into the cell (Richardson, et al.,
1955). Acid phosphatase. an enzyme
which has been clearly shown to be asso-
ciated with lysosomes (deDuve, 1959),
was not found in the subapical cytoplasm
of the midgut gland cells of Nassarius
obsoletus. This finding is of special
interest in view of the current concept of
the mechanism of intracellular digestion
in which lysosomes play a central role
(deDuve & Wattiaux, 1966). This appa-
rent lack of a significant lysosomal com-
ponent correlates well with the histo-
logical picture using conventional proce-
dures in which no evidence of food-
vacuole formation could be observed.

The presence of especially strong este-
rase activity throughout the midgut gland
cells may well reflect a metabolic role
rather than a purely digestive one. for it
is well established that, in addition to
hydrolytic activity, esterases are capable
of participating in synthetic reactions as
well as mediating replacement of ester
components, the latter process being
known as transesterification (Hofstee.
1960).

Esterase activity of the type associated
with cathepsin C was found in the
columnar cells of the midgut glands. As
stressed by Tallan, er al., (1952), intra-
cellular catheptic actıvity results from a
whole family of enzymes rather than a
single proteinase. Cathepsin C has been
shown to be an organophosphate-resistant
member of this family which is homo-
specific with chymotrypsin with regard to
substrate specificity. Again, the physio-
logical role of this enzyme is not clear:
it is believed, however, that catheptic
activity plays a role in the biosynthesis
of the peptide bonds of proteins and of

naturally occurring peptides (Fruton &
Simmonds, 1958).

Especially strong leucine amino pepti-
dase activity was found in the gland of
Leiblein septal cells and in the epithelial
cells lining the second part of the intes-
tine. Its presence in the gland of Leiblein
may well be correlated with the secretory
activity of that organ, but its presence in,
and restriction to, the posterior region of
the intestine is of unknown significance.

Beta-glucuroridase activity was found
to be present in the midgut gland of N.
obsoletus. This enzyme is one of the
hydrolytic enzymes also krown to be
often linked with lysosomal particles
(deDuve, 1959; deDuve & Wattiaux,
1966) although in the midgut gland cells
of N. obsoletus, the enzymatic activity
was distributed throughout the entire
cytoplasm. The presence of /-glucuro-
nidase has been histochemically rendered
visible in gastropod tissue previously
(Billet & McGee-Russell, 1955, in Helix).
and in a survey study, Dodgson, er al.,
(1953) have biochemically demonstrated
its presence in a number of marine gastro-
pods including the rachiglossans Nucella
lapillus and Buccinum undatum. These
latter investigators concluded that, on the
basis of the variety of gastropods which
possessed /-glucuronidase activity, there
was apparently no strict correlation with
habitat or feeding preferences. They did
point out, however, that it was possible
that the enzyme plays a digestive role.
inasmuch as many of the marine algae on
which some of these snails feed contain
polysaccharide material rich in uronic
acid residues. This type of functional
role appears very probable for the 8-glu-
curonidase of Nassarius obsoletus.

IV. IN VITRO ENZYME ANALYSES.
1. Materials and methods

Preparation of tissues: All tissues used
were from recently collected snails which

478 STEPHEN C. BROWN

were maintained in running seawater
aquaria at the Marine Biological Labora-
tory, Woods Hole, Massachusetts. The
shells of the snails were gently cracked
using а “C”-clamp and the soft parts
removed in toto by grasping the colu-
mellar muscle with a pair of watchmaker’s
forceps. The tissues investigated were
carefully dissected out under а stereo-
microscope. Only posterior midgut glands
were used, as these could be freed most
cleanly from adjacent tissues (stomach
caecum and gonad). The gland of Lei-
blein and salivary glands could be cleanly
separated from their adjacent organs, the
esophagus and cerebral ganglia respec-
tively. The excised tissue was then quickly
rinsed in cold distilled water and placed in
cold (O°C) molluscan Ringer’s solution
without buffer (Cavanaugh, 1956). The
cold tissues were subsequently homo-
genized at low speed in a glass tissue
grinder with a teflon pestel and the result-
ing homogenate was allowed to stand in
the cold for 1 hour with intermittent
agitation. The preparation was then cen-
trifuged for 10 minutes at ca. 3000 rpm
to remove the larger unsuspended parti-
cles. The supernatant was decanted and
assayed for enzymatic activity.

Crystalline styles were removed from
animals, quickly rinsed in cold distilled
water and only those portions of the styles
containing no obvious debris allowed to
dissolve in cold molluscan Ringer's.
Stomach fluid was obtained by making
a slit in the caecum where it lies adjacent
to the surface of the visceral mass and
inserting a fine-tipped Pasteur pipette
into the lumen. Special care was taken
to insure that no midgut gland material
was inadvertently picked up. The stomach
fluid was immediately put into cold
Ringer’s solution. In an effort to elimi-
nate bacterial contamination, both the
crystalline style and stomach fluid pre-
parations were then filtered through a
0:22 micron Millipore filter held by a

Swinnex filter apparatus (both from Milli-
pore Filter Corp., Bedford, Mass.). The
resulting solutions were assayed for enzy-
matic activity.

Determination of enzymatic activity:
Disaccharase, amylase, and cellulase activ-
ities were estimated by measuring the
liberation of glucose from the various
substrates. The reaction mixture for the
disaccharase determinations contained
1:0 ml enzyme preparation, 10 micro-
moles of sugar (maltose, cellobiose, suc-
rose, melibiose, or lactose) and 100
micromoles of buffer, made up to a final
volume of 2:0 ml. The reaction mixture
for the amylase determinations contained
1-0 ml enzyme preparation, 01 mg
starch or glycogen and 100 micromoles
buffer, made up to a final volume of
3.0 ml. The reaction mixture for cellu-
lase determinations was identical to those
for amylase determinations with sodium
carboxymethyl cellulose as substratum.
Phosphate buffer was employed in the
experiments, at pH 6:0 for the disaccha-
rases, and at pH 7:0 for the amylases and
cellulases. All reactions were run at
20°C from 2 to 24 hours. Toluene was
added to the reaction mixtures to inhibit
bacterial activity on all runs over 3 hours.
Reactions were stopped by the addition
of equimolar amounts of Ba(OH), and
ZnSO, according to the method of
Weichselbaum & Somogyi (1941). Glu-
cose in the protein-free supernatant was
determined with the “ Glucostat ” reagent,
with the exception that the reagent was
dissolved in 0:25 М tris (hydroxymethyl)
—aminomethane—HC1 buffer instead of
phosphate. This modification has been
introduced (Dahlqvist, 1961) to inhibit
maltase present in commercial prepara-
tions of glucose oxidase. Control tubes
containing only tissue preparations, or
only substrate, in buffer, were run simul-
taneously with all experimental mixtures,
and enzymatic activity was taken as the
difference in the amount of glucose in the

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 479

experimental tube and the amount of
glucose in the control tubes. One ml
samples of the enzyme preparations were
precipitated with trichloroacetic acid
(TCA) at a final concentration of 5%
and set aside for tissue protein determi-
nations. Colorimetric determinations on
all experiments were made with a Cole-
man Jr. spectrophotometer.

Esterase and lipase activity were esti-
mated by the method of Seligman &
Nachlas (1963) in which 2-naphthol liber-
ated from 2-naphthyl laurate is coupled
with tetrazotized O-dianisidine to give a
purple azo dye which is then extracted
with ethyl acetate and determined colori-
metrically. The reaction mixture con-
sisted of 1:0 ml enzyme preparation, 500
micromoles buffer, 10 micrograms sub-
strate, with or without 1-0 ml 8 “10 ? M
sodium taurocholate, made up to a final
volume of 7:0 ml. The buffers used were
phthalate-NaOH at pH 5'5 and 6-0;
phosphateat pH 5-5, 6056-5, 7:0,:7:25,
TS 1.75, and 8:0; barbiturate-HCI at
pH 8:0. 8:25, 8:5 and 9:0; and glycine-
NaOH at pH 9:0, 9:5 and 10°0. All
reactions were run at 20°C for 2 hours
and stopped by the addition of TCA to
give a final concentration of 5%. One
ml samples of the enzyme preparations
were precipitated with TCA and set aside
for tissue protein determinations. Control
tubes containing only tissue preparations,
or only substrate, in buffer, were run
simultaneously with all experimental mix-
tures and esterase activity was taken as
the difference in the amount of 2-naph-
thol in the experimental tubes lacking
taurocholate and the amounts of 2-naph-
thol in the control tubes. Similarly,
lipase activity was taken as the amount
of 2-naphthol liberated in the presence
of taurocholate in excess of the total
amount in the tubes lacking taurocholate
and the control mixtures.

Protease activity was estimated by
measuring the liberation of TCA-soluble

protein from TCA-insoluble protein
(casein and bovine serum albumen).
The reaction mixture consisted of 1:0 ml
enzyme preparation, 0°l mg substrate,
and 100 micromoles of phosphate buffer
(РН 6:0 and 8-0), made up to a final
volume of 3:0 ml. Control tubes con-
taining only tissue preparations, or only
substrate, in buffer, were run simul-
taneously with all experimental mixtures.
Protein in this assay as well as the protein
in all preceding assays was measured by
the method of Lowry, ef al. (1951).

2. Results

Enzymatic cleavage of disaccharides:
Table 3 shows the distribution of disac-
charase activity in the organs examined.
It can be seen that maltose and cellubiose
were hydrolyzed by all the tissues tested.
with highest activity recorded for the
crystalline style, stomach fluid, and gland
of Leiblein. Midgut gland preparations
were able to hydrolyze the a- and f-galac-
tosides in low amounts and the stomach
fluid also had trace amounts of activity.
The gland of Leiblein, in contrast, shows
ecnsiderable hydrolytic activity with lac-
tose as substrate. Invertase (sucrase)
activity did not parallel maltase activity
at all, rather it was found only in the
midgut gland with traces of activity ın
the stomach fluid.

Enzymatic cleavage of polysaccharides:
Hydrolysis of starch, glycogen, and
sodium carboxymethylcellulose is shown
in Table 4. Highest activities were found
in extracts of the crystalline style and in
stomach fluid with starch and glycogen
as substrates. Midgut gland prepara-
tions also showed some activity with
these substrates. Midgut gland prepara-
tions showed moderate activity. and
stomach fluid low activity, with carboxy-
methylcellulose as substrate.

Esterase—lipase activity in midgut gland
hamogenates: The histochemical investi-
gations reported above (part 2) had shown

480 STEPHEN €. BROWN

TABLE 3. Disaccharase activity in Nassarius obsoletus. (Activity expressed as micromoles substrate
hydrolyzed/gram tissue protein/hour. All experiments run at pH 6'0 at 20° С.)

Organ Maltose Cellobiose Sucrose | Melibiose

Lactose
Salivary glands 230 58-8 nil nil mil
Gland of Leiblein 420 1860 nil | nil 563
Crystalline style 3800 36-0 nil nil nil
Stomach fluid 1710 59-0 trace trace trace
Midgut gland 287 66:5 278 6-94 34.7

TABLE 4. Amylase and cellulase activity in Nassarius obsoletus. (Activity expressed as micromoles
glucose liberated/gram of tissue protein/hour. All experiments run at pH 7-0 at 20° C.)

| | Sodium
Organ | Glycogen | Starch carboxymethyl-

| | cellulose
Salivary glands | nil | trace | nil
Gland of Leiblein | trace | trace | trace
Crystalline style | 2650 | 2790 | trace
Stomach fluid | 1090 | 1170 | 27-0
Midgut gland | 415 | 439 196

| |

TABLE 5. Protease activity in Nassarius obsoletus. (Activity expressed as micrograms protein rendered
soluble/gram of tissue protein/hour. All experiments run at pH 6°0 at 20° С.)

glands Leiblein | gland kuid

te er | 2 +++ rn Te

TCA-soluble protein | nil | 2380 | 260 | 7220
the presence of strong non-specific este- however, gave equivocal results. The
rase activity in the midgut gland; the method of Seligman & Nachlas (1963)
technique for demonstration of lipase by was used to determine whether any

means of the Gomori Tween method, differences could be detected in vitra

DIGESTIVE SYSTEM OF

between esterase activity and lipase activ-
ity. With the technique employed it
appears that there is indeed a lipase
present. Maximum activities for the
tissue homogenate are similar for both
enzymes (803 micromoles/gram protein/
hour for the esterase and 850 micromoles/
gram protein/hour for the lipase). How-
ever, as the pH dependency curves show
(Fig. 33), the shape of the curves and the
pH optima for the enzymes are clearly
different. The lipase optimum appears
to be about 7°5, while that for the esterase
151825.

Proteolytic activity: Enzymatic hydro-
lysis of protein is shown in Table 5. The
values given are for the maximum activity
measured with casein as substrate at
pH 6:0. Lower but significant activity
was observed at pH 8:0 with casein as
substrate, but only traces of activity were
observed with bovine serum albumen as
substrate, either at pH 6:0 or 8:0.

3. Evaluation of results

From the results on hydrolytic activity
reported above, one can draw some
reasonable, if not highly specific, conclu-
sions about the enzymatic complement of
the digestive system of Nassarius obso-
letus.

Disaccharide and polysaccharide sub-
strates were chosen so as to give the
presumably complete set of glycosidic
linkages which are thought to be of
paramount importance in determining
glycosidase specificity (Veibel. 1950).
Thus, for maltose to be hydrolyzed, an
a-glucosidase must be present: similarly
for cellobiose, a P-glucosidase: for suc-
rose, an invertase (4-glucosidase or В-Ёгис-
tosidase); for melibiose, an «-galactosi-
dase; for lactose, a P-galactosidase: for
elycogen and starch, an amylo-1, 4-glu-
cosidase; and for cellulose, а 0-1, 4-glu-
cosidase (cellulase). Since most enzyme
characterizations have been done with
yeast and bacteria as source materials,

NASSARIUS OBSOLETUS 481

1000

+
о
о

200

micromoles 2-naphthol liberated /дгат,/ hour

о
a
о

6.0 70 8.0 9.0 10.0

FIG. 33. Lipase-esterase pH curves from midgut
gland homogenates. Circles=lipase; squares=
esterase. Closed figures=single determination:
open figures--mean of 3 determinations.

only general comparisons can be drawn.
Two classes of enzymes are known to
act on the disaccharide sucrose, namely
a-glucosidases (glucosido-invertases) and
P-fructofuranosidases (Neuberg & Mandl.
1950). The animal invertases that have
been sufficiently characterized, however.
are all of the glucosido-invertase type
(Myrback, 1960). There has been con-
troversy over whether or not maltase and
invertase (sucrase) activity results from
two types of enzyme or from a single
a-glucosidase with low specificity with
regard to the aglucon moiety. The evi-
dence is somewhat conflicting, but data
on metazoan enzymes indicate that ani-
mal maltase is incapable of acting on
sucrose (Gottschalk, 1950). From the
distribution of maltase activity shown in
Table 3, it appears that since tissue pre-
parations, run simultaneously, showed
maltase activity but had no hydrolytic
effect with sucrose as substrate, there 15
a true maltase present in at least the
salivary glands, gland of Leiblein, crystal-
line style, and stomach fluid. The find-
ing of both maltase and sucrase action in
the midgut gland (and their near equality

482 STEPHEN C. BROWN

in activity) may indicate that there is a
single relatively unspecific a-glucosidase
present whose lower activity is perhaps
an indication of a metabolic role rather
than a purely digestive ore. The site of
origin of the high maltase activity in the
stomach fluid and style is not clear. The
organs which are known to release pro-
ducts into the digestive tube (salivary
glands, gland of Leiblein, and midgut
gland; Fretter & Graham, 1962; Hyman,
1967) appear to have too little maltase
to contribute significantly to the extre-
mely high activity found in the style.
The substance of the style (principally
mucoprotein) is thought to be secreted
by the typhlosoles of the style sac and
perhaps these structures are also respon-
sible for secretion of enzymes which are
absorbed on to the style, the activity in
the stomach fluid resulting from the dis-
solution of the style and concomitant
release of enzymes (Morton, 1958a).
Cellobiase (/-glucosidase) activity was
observed in all the organs examined, but
was especially high in the gland of Lei-
blein, an organ whose apocrine secretion
has been referred to before. The prob-
lem again arises as to whether a true
cellobiase is responsible or whether a
rather broad range Ä-glucosidase is acting.
In a review of the subject, Pigman (1941)
concludes that the evidence does not
favor the concept of one enzyme respon-
sible for the hydrolysis of all B-glucosides.
He proposed that ** £-glucosidase ” is not
a single enzyme, strictly speaking. but
rather a class of closely related enzymes,
which all show an ability to hydrolyze
?-glucoside linkages. However, Fisher
(1964), working with a partially-purified
8-glucosidase from the roach, Blaberus
craniifer. found that this presumably
single enzyme was able to hydrolyze six
P-glucosides including cellobiose, phenyl-
P-D-glucoside, p-nitrophenyl-p-D-gluco-
side, salicin, arbutin, and gentiobiose.
The foregoing does not take into

account enzymes which are active on long
chainB-glucoside polymers such as cellu-
lose and its derivatives. Evidence on this
score is much more satisfactory as it has
been repeatedly shown that cellulases
from widely different sources attack only
the polysaccharide; that cellobiose is the
smallest product formed; and that cellu-
lase and cellobiase can be separated into
distinct entities, chiefly by chromato-
graphy (Pigman, 1950). From the data
presented in Tables 3 and 4 it would
appear safe to say that a cellobiase (or a
P-glucosidase with a marked specificity
for cellobiose) is present in the gland of
Leiblein and that the activity observed in
the stomach fluid and crystalline style has
as its site of origin the apocrine secretion
of the gland of Leiblein. The activity in
the midgut gland is presumably endo-
genous and may or may not be correlated
with the cellulase activity reported below.
А small amount of 4-galactosidase
activity was detected in the midgut gland
using melibiose as substrate. Studies on
yeast glycosidases indicate that a-galac-
tosidase is a true entity, being separable
from other glycosidases (Veibel, 1950).
The low activity detected in the midgut
gland perhaps indicates a metabolic func-
tion rather than a truely digestive one.
The /-galactosidase activity found in
the gland of Leiblein and midgut gland
may be due to a relatively unspecific
8-glucosidase found in the organs. It is
known that practically all £-glucosidase
preparations are able to hydrolyze /-
galactosides, although there exist P-galac-
tosidases which can be freed of B-gluco-
sidase activity (Veibel. 1950). Beta-glu-
cosidase and P-galactosidase activities in
Nassarius obsoletus can readily be inter-
preted as resulting from enzymes solely
of the #-glucosidase type showing | to 1/3
the activity with a P-galactoside as sub-
strate. Unlike the evidence suggesting
the existence of a specific cellobiase,
there have been no studies reported in

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 483

which a lactase has been separable from
B-galactosidase activity.

Alpha-amylase of metazoan origin is
known to catalyze the hydrolysis of o-1,
4-glucosidic linkages of polysaccharides
such as starch, glycogen and their deri-
vatives. It has been further characterized
as being distinct from 4-glucosidases
which act on smaller molecules; as having
no hydrolytic activity on the a-1, 6-glu-
coside branch points in complex poly-
saccharides; and as having as its primary
products larger oligosaccharides (dex-
trins) which are later broken down to
yield maltose, isomaltose, and branched-
chain products of low molecular weight
(Baumann & Pigman, 1957). The amy-
lase values shown in Table 4 are derived
from somewhat indirect evidence, namely
the formation of glucose. Since all pre-
parations with presumed amylase activity
also have high maltase activity, there
seems no reason to doubt that ап «-amy-
lase is present which converts the starch
and glycogen into disaccharides, which
in turn are broken down by endogenous
maltase liberating glucose.

Cellulases act on the 3-glucoside link-
ages of complex homopolymers such as
cellulose and its derivatives. It is the
consensus that, as for the %-amylases, the
cellulases have distinct enough properties
to warrant separation from a-glucosidases
(Pigman, 1950). Little significance, how-
ever, can be attached to the cellulase
activity shown in Table 4, for although
the first unequivocal preparation of a
cellulase was derived from a gastropod
mollusc (the pulmonate, Helix). further
studies have shown that many of the
reported cellulases of presumed animal
origin were, in fact, due to microbial
contamination (Florkin & Lozet, 1949);
Stone & Morton, 1959). Although both
filtration and toluene were used to remove
possible bacterial activity in the tissue
preparations, the resulting cellulase activ-
ity must be viewed cautiously since it is

known that microbial cellulases are of
the soluble extracellular type which would
not be removed by filtration or added
toluene. Isolation and cultivation of
bacteria present in the tissues and gut of
Nassarius obsoletus appears to be the only
way to resolve the source of the enzyme.

Definitions of the terms lipase and
esterase have usually been based on the
chain length of the carboxylic acid.
Thus, “ lipase ” has referred to esterases
capable of attacking fatty acid esters with
a long carbon chain, especially, fats, and
““ esterases ” (or “ aliesterases ”) to en-
zymes attacking short-chain aliphatic
esters. More recent classification divides
fatty acid esterases into esterases acting
on substrates in solution (esterases proper)
and esterases (lipase-type esterases) which
act predominantly on undissolved sub-
strates (Hofstee, 1960). In the method
employed in this study, a suspension of
2-naphthyl laurate was used as substrate.
The principal of the determination is that
lipase and esterase hydrolyze 2-naphthyl
laurate to 2-naphthol and lauric acid. In
the absence of а surface-active agent
(taurocholate) most of the hydrolysis is
due to esterase, while in the presence of
taurocholate the hydrolysis is due to
lipase and esterase. The difference pre-
sumably corresponds to lipase activity.
As Fig. 33 indicates, there is considerable
hydrolytic activity (ca. 800 micromoles/
gram/hour) shown towards the substrate.
Addition of a surface-active agent more
than doubles the rate at which the sub-
strate is hydrolyzed by the preparation,
and this activation, when plotted relative
to pH, indicates that most probably an
esterase of the lipase-type is present along
with their esterases.

Proteases are usually classified as exo-
peptidases or endopeptidases according
to whether they act on terminal (amino
or carboxy) amino acids or internal pep-
tide linkages. From the protease activ-
ities presented in Table 5, and from. the

484 STEPHEN C: BROWN

TABLE 6. Summary of hydrolytic enzymes detectable in the digestive system of Nassarius obsoletus
by in vitro methods. Preparations of high activity are italicized.

Source | Enzymatic activity

|
|
| Substrate
|

Salivary glands

Gland of Leiblein

Crystalline style

Stomach fluid

a-glucosidase
P-glucosidase

a-glucosidase
P-glucosidase
protease

a-glucosidase
£-glucosidase
a-amylase

a-glucosidase
B-glucosidase

a-amylase

maltose
cellobiose

maltose
cellobiose
casein

maltose
cellobiose
starch, glycogen

(cellulase?) carboxymethyl-cellulose
protease casein
Midgut glands a-glucosidase maltose

P-glucosidase cellobiose
a-galactosidase melibiose
3-galactosidase lactose
glucosido-invertase sucrose
a-amylase starch, glycogen

| (cellulase?) carboxymethyl-cellulose

| esterase 2-naphthy! laurate

| lipase 2-пар ПУ! laurate
protease | casein

method of determining protein (namely
by coloration of aromatic amino acids),
it would appear that the only type of
protease capable of rendering soluble
enough aromatic amino acid residues to
give such high readings would be of the
endopeptidase category. The resulting
soluble protein is most probably a mix-
ture of relatively short-chained peptides
rather than a solution of amino acids.
From the fact that greater activity was
observed at pH 6`0 than was seen at
pH 8-0, it may be tentatively assumed
that the enzyme is of the trypsin
type.

Table 6 summarizes the enzyme com-
plement of the digestive organs of Nassa-

rius obsoletus as revealed by this in vitro
study.

Y. ASPECTS ОЕ DIGESTIVESERYS
OLOGY AND BEHAVIOR

Much of the general behavior of
Nassarius obsoletus has been discussed
by Dimon (1905), Copeland (1918), Jenner
(1956a, 1957 and 1958), Scheltema (1964),
and Carr (1967). The following isa
brief synthesis of the knowledge relating
to distribution and feeding activities,
drawn from the above-mentioned studies
and confirmed and (in places) amplified
by the present investigator.

1. Nassarius obsoletus is found op mud/

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 485

sand flats from a few inches above the
average low tide level to approximately
10 or 12 feet below it.

2. The tidal flats on which N. obsoletus
occurs are characteristically rich in organic
material.

3. On these tidal flats. N. obsoletus
is the numerically dominant gastropod
species.

4. The distribution of these snails is
not random; the snails showing, instead,
a marked tendency for forming (and
apparently, shifting and reforming) exten-
sive aggregations.

5. In these aggregations, N. obsoletus
is present in enormous numbers. Data
from the Invertebrate Zoology class at
the Marine Biological Laboratory at
Woods Hole gave peak densities of 5860
snails per meter? for aggregations of adult
snails at North Falmouth, Massachusetts
(F.M. Fisher, personal communication).
The biomass of living snail tissue at this
density (at 0°5 gm living tissue/snail)
equals approximately 3 kilograms/meter?.
Scheltema (1961) reports densities of
23,000/meter? for newly-settled larvae.

6. On the mud-sand flats. Nassarius is
usually found moving very slowly along
the surface, scooping up quantities of
the substratum with its proboscis only
partially extended (Fig. 35).

7. Nassarius will feed only when com-
pletely covered by water, or at least when
there is enough water present to cover its
shell aperture.

8. N. obsoletus in nature is primarily a
deposit-feeder. The stomach contents of
snails examined in the field uniformly
consisted of great quantities of sand, mud,
and organic detritus.

9. Nassarius in nature has been ob-
served to feed actively on the larger algae
(such as Ulva) and in the laboratory it
will graze on algal scum covering the
walls of aquaria.

10. In nature and in the laboratory.
snails show a marked preference for the

10.0

8.0

РН 70

6.0

НС! added ——+

+—— NaOH added

FIG. 34.
in solution.

Titration curve of crystalline styles

flesh of dead animals. Nassarius has
been observed to eat the following (dead)
animals: Mya, Mytilus, Modiolus, Nassa-
rius, Littorina, Nereis, Squilla, hermit
crabs, and frozen shrimp (Penaeus). In
addition, Dimon (1905) reports observing
a living nereid being devoured by a
cluster of Nassarius in the field, but this
was apparently an exceptional instance.
Il. N. obsoletus exhibits а distinct
behavioral response to the presence of
decaying meat. In order of occurrence.
the following events take place: (а) Initial
detection of soluble diffusing substances
from the meat leads to an overall in-
creased activity. Animals which are par-
tially or completely buried extend their
siphons and, after a short interval. come
rapidly to the surface of the substratum.
(b) This increase in activity is immediately
followed by relatively rapid forward
locomotion accompanied by a constant
sweeping of the siphon from side to side
in approximately 120° arc in front of the
snails. (с) After a brief period of ran-
domly-directed forward locomotion, the
snails orient themselves against the direc-
tion of the current flow (rheotaxis) and
move upstream. (d) The snails continue

486 STEPHEN C. BROWN

FIG. 35. Nassarius obsoletus with proboscis extended as far as the substratum. This is its normal posi-

tion when the animal is feeding on surface detritus.

movement upstream with “ searching ”
movements of their siphon and, as the
meat is neared, the proboscis is extended
and radular action begins (Fig. 36). (e)
Upon reaching the meat, the proboscis is
applied to the surface and, by radular
action, the proboscis literally bores a
hole deep into the food mass (see also
Carr, 1967a and 1967b).

12. That the initial response to meat is
chemical rather than visual 1$ easily
shown by the following facts: (a) In
nature, animals which are close by, but
upstream from, a decaying piece of meat
do not become characteristically active or
exhibit any of the behavioral traits asso-
ciated with the detection of meat (as in
11, above). On the other hand, animals
which are much farther away, but down-
stream, from the same piece of meat do
become active and go through the search-
ing movements, eventually reaching and

eating the meat. (6) In the laboratory, a
single drop of meat juice introducted into
the aquarium is sufficient to elicit the
easily-observed responsive activities dis-
cussed under 11 (a-b), above.

13. Clear evidence for a rheotaxis is
provided by the behavior of animals in
nature preparatory to feeding [as in 11
(c), above] and by the following observa-
tions of animals under laboratory condi-
tions: (a) If a drop of meat juice is added
to a battery jar containing snails and the
water stirred so as to give a unidirectional
current (clockwise, for example), the
animals become active and, after a few
moments of randomly-directed locomo-
tion. move with searching movements
against the direction of the current
(counterclockwise in this case). By
reversing the direction of the current, the
animals will turn 180° in their path and
more as before against the current. (5) If

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 487

a piece of meat is dropped into the middle
of an aquarium in which the water has
been allowed to become still, the snails
become active, but mill about with no
uniform directional heading. Those that
do perchance contact the meat stop and
begin feeding, and thereby many snails
eventually find the food, but by the
mechanism of klinokinesis (Fraenkel &
Gunn, 1940) rather than by a directed
taxis.

The time of retention of food in the
digestive tract has been used as an indi-
cation of the efficiency of the digestive
process (Prosser & Brown, 1961). In N.
obsoletus just taken from its natural
habitat and isolated in aquaria, the gut
is completely emptied of sand and mud
in approximately 12 hours. Observations
on previously-starved animals fed on
frozen shrimp indicate that the passage
of this type of food is completed more
rapidly, often in as short a period as
4 hours. Whether or not the observed
feeding times can be directly correlated
with the “efficiency of the digestive
process ‘ remains an unanswered ques-
tion. Nevertheless, it would not be too
surprising if the digestion of organic
material within a matrix of sand and mud
particles would be less efficient than
digestion of a concentrated *“* pure ” food
form such as animal tissues. What phy-
siological mechanisms may be involved in
regulating the speed of food flow through
the gut can only be guessed.

As Jenner (1956b) has pointed out, the
mechanism of primary importance in pro-
pulsion of material through the digestive
tract is one of peristaltic contraction of
the walls of the alimentary canal. As
has been shown (part |, above), the mus-
culature surrounding the various portions
of the gut is well-developed, and thus the
anatomical basis for such peristaltic
movements is clearly established.

The formation of fecal material, its
consolidation and elimination, are thought

to have been at least partially responsible
for many of the evolutionary specializa-
tions found in the Gastropoda (Гог
example: the extensive elaboration of
mucous glands in the intestine: the for-
mation of food/fecal strings: the shift of
the anus to the right side of the pallial
cavity: the great reliance on, and success
of, the pectinibranch ctenidium: the shift
in pallial water currents from ventro-
dorsal to lateral: and so on). In light of
such theoretically important considera-
tions, it is of interest to note the condi-
tions which obtain in Nassarius obsoletus.
Although mucous goblet cells abound in
the intestinal region, no discrete consoli-
dated fecal pellets, such as are known
from microphagous hervibores, are
formed Бу N. obsoletus. И animals are
taken from the field and placed in clean
seawater-filled finger bowls, defecation can
be observed and fecal products examined.
The great bulk of expelled material con-
sists of sand particles which have mucus
adhering to them. The mucus has insuffi-
cient binding capability, however, to hold
the heavy sand grains together in a fused
mass. Presumably the size and weight
of the particles cause them to settle
rapidly out of the mantle cavity and thus
prevent them from interfering with the
ctenidium and the respiratory currents.
Lighter and more finely divided material
is held together somewhat better than the
sand grains, but the compactness of con-
solidation does not approach that found
in forms subsisting solely on a diet of
minutely-divided particulate material.
Characteristic of the molluscan stomach
is the presence of numerous ciliated folds
and ridge systems which act as particle
“sorting fields ”. These are particularly
well-developed in the lamellibranch Bival-
via and in those Archaeogastropoda and
Mesogastropoda which are of the con-
tinuously-grazing microherbivore type.
The food strings and crystalline styles of
lamellibranchs and style-bearing proso-

488 STEPHEN C. BROWN

branchs are likewise propelled by exten-
sively ciliated surfaces. In N. obsoletus,
the entire alimentary canal with the excep-
tion of the caecum is lined by ciliated
epithelium as shown in part 1. The
stomach, however, is simplified with
regard to sorting fields in comparison to
most of the lower gastropods. It does,
however, retain vestiges of organized
ciliated fields which are often absent in
the more specialized Neogastropoda. The
following ciliary currents were determined
by the use of finely divided particulate
material such as carmine and carbo-
rundum.

Issuing from the esophageal opening
(Fig. 18, OPE), a relatively weak current
proceeds posteriorly for a very short
distance and then terminates abruptly at
the anterior edge of the caecal folds. No
ciliary activity could be observed along
the folded walls of the caecum itself. To
the left of the esophageal opening a series
of currents run along the small transverse
folds converging on to the smooth saddle-
shaped area (SSA). Although this region
of transverse folds most closely resembles
a sorting field of the type found in lamelli-
branchs and lower gastropods, there is
no sign of the characteristic separation of
particles by size or of the presence of two
currents perpendicular to each other to
effect such a separation.

To the right of the esophageal opening
are found currents issuing from the open-
ings of the migdut glands and a current
directed away from the ventral midline
across the large area of smooth epithelium
adjacent to the gastric shield. Within
the sulcus forming the posterior boundary
of the typhlosoles are found strong cur-
rents directed medially towards the ventral
intestinal groove. A strong current con-
tinues along the floor of this groove
carrying particles entrapped in mucus
anteriorly toward the intestine. Strong
ciliary activity is found on both typhlo-
soles: a posteriorly-directed current along

the face of the minor typhlosole (MiT)
presumably forces the crystalline style
backward against the gastric shield, while
ciliary activity directed medially along the
surface of the major typhlosole (MaT)
causes the style to rotate in a clockwise
direction when viewed from the rear.
Currents on the sides of the typhlosoles
are directed ventrally and serve to carry
particles into the anteriorly flowing cur-
rents of the intestinal groove.

In Nassarius obsoletus, therefore, there
is no evidence that the stomach accom-
plishes any particle separation through
the mechanism of ciliary sorting fields.

Perhaps the most notable feature of the
stomach of Nassarius obsoletus is the
presence of a crystalline style. Func-
tionally, the crystalline styles of lamelli-
branchs and lower gastropods are thought
to act as: (1) repositories for digestive
enzymes: (2) “ capstans ” which aid in
drawing mucus food strings into the
stomach; and (3) buffer sources to main-
tain the pH of the stomach fluid (Morton,
1952 and 1960). It is of interest to note
how the style of №. obsoletus compares
with styles found elsewhere in the Mol-
lusca with regard to these functions.

It has been clearly demonstrated that
the style of Nassarius obsoletus does con-
tain hydrolytic enzymes (part III, above).
It is unlikely, however, that the style of
these animals in nature acts as a capstan
to any significant extent, since, as has
been discussed above, the bulk of ingested
material is sand and coarse mud (coated,
but not tightly bound, by mucus) which
is passed along the alimentary canal by
muscular peristalsis.

In an effort to determine whether or
not the style of Nassarius obsoletus has
any buffering capability, 10 styles were
allowed to dissolve in 10°0 ml of glass-
distilled water. The resulting solution
was titrated with 0:01 М НС! and 0:01 N
NaOH and the pH determined with a
Sargent model PB pH meter. The titra-

DIGESTIVE SYSTEM ОЕ NASSARIUS OBSOLETUS 489

tion curve is given in Fig. 34. It shows
buffering action between pH 5:8 and 7:2,
the midpoint being at pH 6°5. This
agrees well with values for the stomach
fluid of pH 6:0-6:5 obtained by the use
of indicators (bromthymol blue and
bromcresol purple).

The style of Nassarius obsoletus, there-
fore, apparently does have a buffering
function in addition to the enzymatic one
discussed above.

VI. GENERAL DISCUSSION

Studies on the functional morphology
of molluscs by Atkins, Fretter, Graham,
Morton, and Yonge, among others
(reviewed by Morton, 1958a; Fretter &
Graham, 1962: Wilbur & Yonge, 1964;
Owen, 1966; and Hyman, 1967), offer
convincing evidence that the first mol-
luscs most probably all fed on small
particles. These particles were non-selec-
tively scraped up from the substratum by
the radula, bound by mucous secretions
into a “food string ”, transported along
the alimentary canal by ciliary activity,
and eventually subjected to phagocytosis
and intracellular digestion within the
blind tubules of the midgut gland. Such
dependence on the intracellular mode of
digestion imposed the requirement that
the food particles presented to the diges-
tive cells be within certain size limits to
allow for phagocytosis. Among the ear-
liest evolutionary features to appear in
molluscs, therefore, were mechanisms
designed to grade and sort particles
according to size and to transport the
sorted particles to their proper destina-
tions within the digestive tract. The
extensive use of mucous secretions to
bind the particulate food material to-
gether for transport through the alimen-
tary canal led to the production, within
the stomach, of a mucoprotein rod, the
forerunner of the crystalline style, or
protostyle. This rod gained increased

functional significance as it assumed the
mechanical burden of drawing the mucus
food-string into the stomach, as it be-
came a repository for extracellular amy-
lases, and as it added a buffering effect
to maintain the pH of the stomach.

The lamellibranch bivalves adopted the
habit of feeding on particles suspended in
the surrounding water and thus avoided
the larger particulate material which
made up the bulk of the ingested matter
of deposit feeders. Further refinement
of food selection was achieved by the use
of ciliary sorting fields on the labial palps
and within the stomach itself. Digestion
in this group has presumably remained
for the most part intracellular, although
a partial breakdown does occur extra-
cellularly of material, such as polysac-
charide, the digestion of which is com-
paratively difficult.

The gastropods, with notable excep-
tions, retained use of the radular appa-
ratus to scrape up food material from the
substratum in а non-selective manner.
Early dietary specialization led some
gastropods to become microphagous her-
bivores, feeding primarily on algal frag-
ments rasped from rocks and other hard
surfaces. Sorting by size of particle was
accomplished almost solely by means of
ciliarly sorting fields within the stomach
—these functioning similarly to those
found in the Bivalvia.

Among living prosobranchs, some of
the Archaeogastropoda and Mesogastro-
poda retain the habit of microphagous
herbivory although the evolutionary trend
has been for gastropods to adopt macro-
herbivorous or carnivorous habits. The
mesogastropod microherbivores — retain
possession of ciliary sorting fields within
the stomach, and certain entire super-
families (Rissoacea, Cerithiacea, and
Calyptraeacea) are characterized by the
possession of a crystalline style. Here,
as in the lamellibranchs, the primary
mode of digestion is intracellular, with

490 STEPHEN C. BROWN

partial extracellular digestion taking place
by means of crystalline style enzymes.
The rachiglossan Neogastropoda (in-
cluding the superfamilies Buccinacea,
Muricacea, and Volutacea) are charac-
teristically carnivorous. The modifica-
tions which have occurred to equip such
snails for a diet of animal flesh include:
(1) development of the rachiglossan
radula, possessing three sharp-cusped
teeth per row, which is extremely well-
suited for tearing bits of flesh from solid
animal tissue; (2) size increase and
elaboration of the proboscis which allows
penetration of the feeding apparatus deep
into animal tissues and into relatively
inaccessible places such as between bivalve
shells and into tunicate tests; (3) exten-
sion of the mantle tissue into a long
movable canal (the siphon) which allows
delicately-controlled intake of the sur-
rounding water which is then directed
over (4) а well-developed bipectinate
osphradium which is employed as a
chemosensory organ for the detection of
food; (5) development of а valvular
device in the esophagus (the valve of Lei-
blein) which allows protrusion and elon-
gation of the proboscis without regurgi-
tation of food material; (6) essentially
complete conversion to extracellular
digestion; (7) specialization of glands

(such as the salivary glands. gland of

Leiblein, and midgut gland) to produce
extracellular enzymes; (8) simplification
of the stomach into a bag where enzymes
and food are mixed and digestion occurs,
and from which soluble material passes
into the ducts of the midgut gland for
absorption; (9) great reduction or com-
plete loss of ciliary sorting fields, since
there is no longer the requirement for
Separation of particles from one another
according to size; (10) loss of a crystal-
line style, since the proteinaceous style
presumably would be digested by the
extracellular proteases of strictly carni-
vorous forms; and (11) great reduction

or more often complete loss of the gastric
shield, since with the crystalline style
absent, there no longer is abrasion be-
tween a style head and the lining epi-
thelium.

The Buccinacea amongst the Neogas-
tropoda are known to be the least spe-
cialized of the carnivorous Rachiglossa.
Within the Buccinacea, members of the
family Buccinidae frequently eat living
flesh, while the family Nassariidae char-
acteristically feed on dead or decaying
animal matter.

The anatomy of the Nassarius species
studied agrees in almost every detail with
the characteristics listed above associated
with assumption of a carnivorous exis-
tence. Thus, the presence of the rachi-
glossan radula, the extremely long and
protrusible proboscis, the long siphon
and bipectinate osphradium, the well-
developed valve of Leiblein, salivary
glands, and gland of Leiblein, the simpli-
fication of stomach structure, the absence
of efficient sorting ciliate regions, and the
reduced gastric shield—all bespeak the
typical carnivorous rachiglossan structure,

Likewise, almost all of the species of
Nassarius are described as being carni-
vorous, subsisting on a diet of dead and
decaying animal flesh (Blegvad, quoted
in Yonge, 1954; Graham, 1955; Morton,
1958a; Fretter & Graham, 1962; and
Martoja, 1964).

In addition to exhibiting the anatomical
characteristics listed above, however, Nas-
sarius obsoletus also possesses a crystalline
style, and in apparent contrast to the
other Nassarius species, N. obsoletus is
clearly a deposit feeder. There can be
very little doubt that in its natural habitat
N. obsoletus receives almost all of its
nutrition from the organic debris found
within the mud and silt of the intertidal
flats. This organic debris to the greatest
extent consists of living unicellular algae,
algal degradation products, and attendant
micro-organisms.

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 491

FIG. 36. Nassarius obsoletus with its proboscis greatly (but not completely) extended. This anima
was preparing to feed on a piece of dead meat (out of camera range).

From Newell's (1964) study, it is ap-
parent that certain deposit-feeding mol-
luscs actually digest only the protein
derived from the microbial coating on
the silt and organic debris. In the two
species of deposit-feeders studied (Hydro-
bia ulvae and Масота balthica), the
amount of ingested organic carbon (pre-
sumably derived from living unicellular
algae and algal degradation products)
was almost totally recoverable in the feces,
while the organic nitrogen ingested
(derived mainly from bacterial synthesis)
was retained (and presumably meta-
bolized) by the molluscs. Although ex-
periments to determine carbon and nitro-
gen ingestion/egestion ratios have not yet
been done for N. obsoletus, the author
concurs with Scheltema (1964) that most
probably the main nutritional component
of the ingested material is the microfloral
carbohydrate and not the bacterial pro-

tein. The presence of crystalline styles
and concommitant absence of extra-
cellular proteases within the stomachs of
№ obsoletus on the mud flats argues
strongly for this conclusion.

From the data presented in this study,
we may attempt to describe Nassa
rius obsoletus, although anatomically a
carnivore, is able to handle a herbivorous
(or more strictly an omnivorous) diet.

The present findings all point to the
fact that intracellular digestion, either by
migrating amoebocytes, or by cells of the
midgut gland, does not occur to any
significant extent. The evidence bearing
on this point includes the observations
that: (1) Nassarius obsoletus clearly lacks
any efficient mechanism (ciliary or other-
wise) to sort and separate particles accord-
ing to size. Such a mechanism is ob-
viously a prime requisite in view of the
extreme variation in size range of the

492 STEPHEN C. BROWN

ingested material. (2) There is no uptake
by the midgut gland cells or amoebocytes
of finely particulate material such as
carmine or carborundum, пог is there
any histological evidence of food vacuole
formation in the midgut gland cells. (3)
Acid phosphatase activity in the midgut
gland cells is confined to the lumenal
border rather than having particulate
localization in the more basal cytoplasm
(which would be expected if phagocytosis,
and hence lysosomal activity, occurred).
(4) No bistological evidence was observed
of amoebocytes being within the lumen
of the digestive tract or between the cells
of the lining epithelium, nor did amoebo-
cytes within the midgut gland haemocoel
show a positive reaction in any of the
histochemical procedures employed for
the demonstration of — hydrolytic
enzymes.

On the other hand, data from the in
vitro enzyme determinations reveal the
presence of a variety of enzymes within
the stomach lumen and in extracts ог the
crystalline style, thus strongly suggesting
that extracellular digestion does indeed
take place. The crystalline style itself
contains several carbohydrate-splitting en-
zymes including a-glucosidase. Æ-glucosi-
dase, and polysaccharases capable of
hydrolyzing starch and glycogen. The
stomach fluid likewise contains enzymes
like those of the crystalline style (and
most probably derived from it) and, in
addition, it has definite traces of gluco-
sido-invertase, 4-galactosidase, S-galacto-
sidase, and cellulase activity. These find-
ings (along with the histochemical and/or
in vitro demonstration of esterase, lipase,
and 4-glucuronidase activity within the
midgut gland) offer strong evidence that
the digestive system of Nassarius obsoletus
has sufficient hydrolytic enzymes to digest
and ultimately metabolize the algal con-
stituents (such as structural polysaccha-
rides and various esters and polymers of
galactose and uronic acids) which form

the greatest proportion of its ingested
food material (Fox, 1950; Black, 1954).

Extracellular protease activity (Table 5)
was found in the stomach fluid of certain
animals just taken from the field, the
styles being absent from these animals.
This fact, and the observation that snails
which were maintained in the laboratory
exclusively on a diet of meat invariably
lacked styles and gastric shields, can best
be explained following Yonge’s (1930)
reasoning that a proteinaceous crystalline
style cannot co-exist with extracellular
proteolytic enzymes without itself being
subject to dissolution by enzymatic action.
The presence of a style in a snail can be
taken as clear evidence for the absence of
extracellular proteases. Animals feeding
on mudflats unquestionably ingest some
animal tissues and micro-organisms as a
matter of course; the presence of a style
indicates, however, that they cannot be
digesting these materials extracellularly.
The ingestion of large quantities of animal
flesh, such as occurs regularly during
laboratory maintainance, or sporadically
in nature, apparently elicits release of
extracellular proteases which digest meat
(as well as style) protein. The intriguing
questions which arise here involve: (1) the
apparent reciprocal relationship between
the presence of a style versus the presence
of extracellular proteases in the lumen of
the stomach; and (2) the influence
(control?) exercised over these by the
type of food ingested.

The site of secretion of the enzymes
found in the stomach fluid and crystalline
style is not known with certainty. It
seems probable, however, that the gland
of Leiblein, midgut gland, and perhaps
salivary gland are chiefly responsible for
such enzyme production. In particular,
the high tissue activities of protease,
a-glucosidase, and B-galactosidase found
in the gland of Leiblein suggest that these
enzymes are derived primarily from this
source. Similarly, it seems not improb-

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS 493

able that the midgut gland is the primary
source of glucosido-invertase, &-galacto-
sidase, and the polysaccharases which act
on starch and glycogen. As stated before,
the origin of the cellulase activity is very
much in doubt—a microbial origin, how-
ever, seems not unlikely.

The site of uptake of the digested food
awaits final clarification from further
studies. The presence in Nassarius obso-
letus of microvilli along the lumenal
border of the columnar cells in the midgut
gland agrees with the findings of Summer
(1966) who, by electron microscopy,
demonstrated the presence of microvillar
brush borders in the midgut gland cells
of the pulmonate Helix. Sumner also
showed the presence of pinocytotic vesi-
cles and channels extending into the
cytoplasm of the midgut gland cells.
Terrestrial pulmonates such as Helix are
macroherbivores in which extracellular
digestion occurs in a thin-walled stomach
and absorption of the soluble food mate-
rial occurs in the midgut gland. It is not
unlikely, therefore, that the midgut gland
of N. obsoletus has a similar absorptive
function.

The presence of phosphatases along the
lumenal borders of the midgut gland cells,
as has been mentioned previously, is also
indicative of metabolically active cell
surfaces. There has been little evidence
until recently that uptake of soluble
digestive products in non-cephalopod mol-
luscs occurs elsewhere than in the midgut
gland tubules. Recent studies by Greer
& Lawrence (1966) and Lawrence &
Lawrence (1966) have shown, however,
that isolated intestinal segments of the
polyplacophoran Cryptochiton stelleri are
able to actively transport basic and neu-
tral amino acids and the monosaccharides
D-glucose, 3-0-methyl glucose, and D-
galactose. The results of these studies
suggests that, for С. stelleri at least, the
gut is of greater importance than the
midgut gland in the uptake of soluble

digestive products. This may well prove
to be true for many other molluscs,
including Nassarius obsoletus.

Following conventional descriptions of
dietary preference and digestive capability,
one must classify Nassarius obsoletus as
an omnivore. The omnivory practiced
by N. obsoletus, however, is significantly
different from that found in most other
animals. Although it is capable of feed-
ing on, and utilizing, both plant and
animal materials, N. obsoletus apparently
“commits” itself to one or the other,
rather than feeding on and digesting
both simultaneously. The “ commit-
ment ” is to some degree forced upon it
by circumstance. The presence of a style
in typical mud flat snails indicates that
no proteases are normally present in the
lumen of the gut and hence even though
some animal material is undoubtedly
taken in, there are no extracellular en-
zymes present to digest it. Such an
animal is functionally a total herbivore.
On the other hand, when a piece of
carrion is present on the mud flats, the
snail shows a strong preference for this
and will attack it to the exclusion of its
normal fare. At such times both pro-
teases and carbohydrases are present in
the stomach, but due to the strong be-
havioral response, the snail has ensured
that it will eat a meal of essentially pure
meat. During this time the animal is
functioning solely as a carnivore. It
seems more accurate, therefore, to classify
the snail as a facultative herbivore/carni-
vore rather than as an omnivore.

The adaptive value of such a digestive
mechanism in a mud flat snail seems
reasonably clear-cut. It permits utiliza-
tion of the algal debris deposited at each
receeding tide and yet allows for the uti-
lization of the occasional bit of carrion
washed up on the flats. The origin of
such a habit is more obscure. Presum-
ably the ancestral stock could not com-
pete in other regions with the more

494 STEPHEN C. BROWN

efficient mesogastropod microherbivorous
grazers such as Littorina or with the more
specialized stenoglossan carnivores such
as the whelks and drills. Its unique
digestive mechanism has permitted evolu-
tionary success in the mud flat habitat.

In conclusion, the data show that
Nassarius obsoletus, although possessing
the many structural modifications asso-
ciated with a carnivorous mode of feeding
and digestion, nevertheless has been able
to utilize a primarily herbivorous diet.
From the anatomical evidence alone, this
appears to be a secondary adaptation
derived from a principally carnivorous
ancestry. There is nothing in the struc-
ture of N. obsoletus to suggest that it is
an intermediate form of а basically
herbivorous line which is in the process
of “ becoming ” carnivorous. Physio-
logically, the presence of secreted hydro-
lytic enzymes and a functional crystalline
style permits extracellular digestion of
algal components—a situation necessi-
tated by the absence of mechanisms for
sorting particles according to size (a pre-
requisite for any significant amount of
phagocytosis and intracellular digestion).
The crystalline style of Nassarius obso-
letus, apparently absent in the other
Nassarius species, is likely a neomorphic
addition. There is no evidence that any
of the Buccinacea have evolved directly
from any of the style-bearing mesogas-
tropod groups, and furthermore it is
thought not unlikely that styles have
been evolved several times within the
Mollusca (Robson, 1922; Yonge, 1932:
and Morton, 1960).

ACKNOWLEDGMENTS

I wish to thank Dr. James N. Cather and
Dr. John M. Allen of the Zoology Department,
University of Michigan, for their encouragement
and help during the course of this study. I
also wish to acknowledge with thanks Drs. John
C. Ayers, Frederick E. Smith, and Henry van
der Schalie, of the University of Michigan, for
their helpful suggestions on the manuscript. To

Di. Frank M. Fisher, I owe special thanks for
space in his laboratory, materials freely given:
and knowledgeable advice during the summer of
1966 at the Marine Biological Laboratory, Woods
Hole, Massachusetts. I owe a particular debt to
Dr. W. D. Russell-Hunter who, by his enthusiasm
and scientific example, interested me in functional
morphology and the phylum Mollusca. I wish
to acknowledge my debt to the National Science
Foundation for their continuous support, through
the Graduate Fellowship program, during the
years 1963-1966. During the summer of 1966,
the Horace H. Rackham School of Graduate
Studies of The University of Michigan generously
provided research funds to cover special expenses
incurred during my stay at the Marine Biological
Laboratory at Woods Holes.

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amounts of ketone bodies. J. biol. Chem.,
140: 5-20.

WILBUR, K. & YONGE, C. M., 1964, Physio-
logy of Mollusca, Vol. 1, Academic Press, New
York, 473 p.

WU, S. K., 1965, Comparative functional studies
of the digestive system of the muricid gastro-
pods Drupa ricina and Morula granulata.
Malacologia, 3: 211-234,

YONGE, C. M., 1930, The crystalline style of
the Mollusca and a carnivorous habit cannot
normally coexist. Nature, Lond., 125: 444-445,

YONGE, C. M., 1932, Notes on feeding and
digestion in Pterocera and Vermetus, with a
discussion on the occurrence of the crystalline
style in the Gastropoda. Sci. Rep. Gt. Barrier
Reef Exped.. 1: 259-281.

YONGE, С. M., 1954, Physiological anatomy of
the alimentary canal in invertebrates. Tabul.
biol., Hague, 21(20): 1-24.

Received for publication Feb. 5, 1968.

Accepted for publication Apr. 25, 1908.

RESUME

LA STRUCTURE ET LE FONCTIONNEMENT DE L’APPAREIL
DIGESTIF DE LA NASSE, NASSARIUS OBSOLETUS (SAY)

S.C. Brown

La nasse des cótes américaines atlantiques, Nassarius obsoletus (Say) est un représentant

des Gastropodes rachiglosses, typiquement carnivores.

Dans la nature, cependant, №.

obsoletus est un mangeur de détritus non sélectif, se nourrissant presque exclusivement

par ingestion de sable et de boue.

La présente étude a été entreprise pour clarifier le

mécanisme du fonctionnement de Гаррагей digestif de l’animal.
Des études anatomiques et histologiques indiquent que Nassarius obsoletus a toutes les
modifications structurales associées а l’acquisition d'un mode de vie carnivore. Ces

modifications comprennent: un proboscis allongé et extensible; une dentition radulaire
rachidienne, un long siphon mobile et une osphradie bipectinée; un pharynx de Leiblein,
une glande de Leiblein et des glandes salivaires bien développées; un estomac simple
possédant un bouclier gastrique tres reduit; pas d'airs de triage ciliées réellement efficaces:
et des couches musculaires entourant le tube digestif fortement développées. En con-
traste avec ces caractéristiques clairement carnivores N. obsoletus possede un stylet
cristallin mucoprotéique dans son estomac: c'est lá un fait en relation avec une adaptation
structurale a un régime herbivore. Des études histochimiques montrent que la glande
digestive contient des enzymes capables de fractionner les esters et les glucuronides et
donc de métaboliser quelques uns des principaux constituants des algues. Des

DIGESTIVE SYSTEM OF NASSARIUS OBSOLETUS

expériences de nutrition portant sur l’utilisation de matériel finement divisé en particules
et sur la localisation de l’activité des phosphatases, montrent conjointement qu'il n'existe
ni phagocytose, ni digestion intracellulaire. Jn vitro les analyses enzymatiques de tissus
provenant des divers organes digestifs, révélent la présence d’estérase lipase, a-amylase,
protéase et de plusieurs disaccharases. Des analyses du suc gastrique et du stylet cris-
tallin révèlent, de façon similaire, la présence d'enzymes extracellulaires à l’intérieur de
la lumière de l'estomac. Au cours d'examen des modes de nutrition et du comporte-
ment, il est apparu avec évidence que, physiologiquement, le stylet cristallin aide la
digestion et qu’on doit par conséquent le considérer comme vraiment fonctionnel plutôt
que comme un simple reste du cordon fécal muqueux.

Selon les données présentées, on en conclut que Nassarius obsoletus, rien que possédant
structuralement toutes les caractéristiques d’un carnivore rachidien typique, est cependant
capable de subsister presque entiérement avec un régime de détritus d'algues; qu'il
possede les enzymes hydrolysantes nécessaires pour attaquer les principaux constituants
des algues; que le début de l’hydrolyse est extra-cellulaire; que la phagocytose et la diges-
tion intra-cellulaire n'ont pas lieu et que l’absorption des produits solubles de digestion
а probablement lieu dans la glande digestive ou au niveau de l'épithelium qui sépare
Pestomac de l’intestin.

AT:

RESUMEN

ESTRUCTURA Y FUNCION DEL SISTEMA DIGESTIVO EN EL
CARACOL DEL BARRO, NASSARIUS OBSOLETUS (SAY)

S.C. Brown

El caracol que habita los barros de la costa del Atläntico de Estados Unidos, Nassarius
obsoletus (Say), pertenece al grupo de los gastrópodos raquiglosos tipicamente carnívoros;
sin embargo, no selecciona su alimento y subsiste enteramente ingiriendo arena y barro.
Este estudio aclara el mecanismo, y función, del sistema digestivo.

Estudios anatómicos e histológicos indican que Nassarius obsoletus tiene todas las
modificaciones estructurales asociadas con una existencia carnívora. Estas modifica-
ciones incluyen: proboscis alargada; rádula raquiglosa; sifón alargado y movible y un
osfradio pectinado; válvula de Leiblein bien desarrollada y glándulas salivares; estómago
simplificado con un escudo gástrico reducido; areas de seleccion ciliar no eficientes y
tejido muscular bien desarrollado alrededor del canal alimenticio. En contraste con
estas caracteristicas tan claramente carnívoras, posee en el estómago un estilete cristalino
mucoproteico—asociado con la adaptación estructural para una dieta herbívora.
Estudios histoquímicos indican que el intestino medio contiene enzimas capaces de
desdoblar esterasa y glucoronidos, para metabolizar algunos de los constituyentes prin-
cipales de las algas. [Experimentos en nutrición, usando materiales finamente divididos
y localización histoquímica de fosfatasa, indicaron que tanto la fagocitosis como la diges-
tión intracelular no tienen lugar. Enzimas in vitro de tejidos de los diferentes Órganos
digestivos revelan la presencia de esterasa, lipasa, amilasa, proteasa y varios disacaridos.
Analisis del fluido estomacal y estilete cristalino, ambos revelaron la presencia de enzimas
hidrolíticas extracelularmente dentro del lúmen del estomago. La revisión de los hábitos
alimenticios se presenta junto con la evidencia fisiológica de que el estilete cristalino
ayuda en el proceso digestivo y es verdaderamente funcional, en vez de ser un remanente
de la mucosa fecal.

En conclusion, aunque Nassarius obsoletus posee todas las condiciones tipicas de un
carnívoro es, sin embargo, capaz de subsistir casi completamente de una dieta de detritos
de algas; produce enzimas hidrolíticas para desdoblar los principales constituyentes de
las algas; el desdoblamiento incial se produce extracelularmente: no hay caso de fago-
citosis O digestión intracelular, y la absorción de los productos solubles de digestión
ocurre probablemente en la glándula del intestino medio o en el revestimiento del
estómago-intestino,

FP:

499

500 STEPHEN C. BROWN

ABCTPAKT

СТРУКТУРА И ФУНКЦИЯ ПИШЕВАРИТЕЛЬНОЙ СИСТЕМЫ ИЛОВОГО
МОЛЛЮСКА NASSARIUS OBSOLETUS (SAY)

©; ©. BROYH

Иловая улитка американского атлантического побережья Nassarius obsoletus
(Say) является представителем типичных хищных моллюсков из рахиглоссных
Gastropoda. В природе, однако, М. obsoletus является безвыборочно-заглаты-
вающим донные осадки: ил и песок. Настоящее исследование было предприня-
то для выяснения механизма работы пищеварительной системы этого моллюс-
ка.

Анатомическое и гистологическое исследование показывают, что М. obsoletus
имеет все структурные модификации, связанные с предположительно хишным
образом жизни, это: удлиненный вытягивающийся хобот, радула с рахиглос-
сными зубчиками, удлиненный подвижный сифон и двугребенчатый осфорадум;
хорошо развитый клапан и железа Леблейна и слюнные железы; просто устрое-
нный желудок с сильно редуцированным гастрическим щитком; отсутствие
хорошо развитой ресничной области; хорошо развитые мускульные слои, ок-
ружающие пищеварительный тракт.

В противоположность этим признакам хищного образа питания, М. obsoletus
обладает в желудке мукопротеиновым кристаллическом стебельком, т.е. ор-
ганом, связанным с адаптацией к растительноядному типу питания. Гистохи-
мическое изучение показывает, что железа средней кишки содержит энзимы,
способные расщеплять эстэры, глюкорониды и таким образом усваивать осно-
вные компоненты водорослей. Опыты по питанию, когла употреблялись тонко
растертые частицы пищи, а также гистохимическая локализация активности
фосфатазы показали, что фагоцитоз и внутриклеточное переваривание не
имеет места.

Энзимовый анализ гомогената тканей in vitro, взятых из различных пищева-
рительных органов, указывает на наличие эстеразы, @ -амилазы, протеазы и
некоторых дисахараз. Анализ желудочного сока и кристаллического стебель-
ка сходным образом показал наличие экстрацеллюлярных гидролитических эн-
зимов внутри желудка. Образ питания и поведения моллюсков, наряду с Qu-
зиологическими данными, указывает, что кристаллический стебелек помогает
процессу пищеварения и является истинно Функциональным, а не остатком
слизистого фекального тяжа.

Из полученных данных видно, что Nassarius obsoletus, хотя и обладает всеми
структурными признаками типичного [хищника из рахидоглоссных гастропод,
тем не менее может суцествовать почти целиком на водорослевом детрите.
Он обладает гидролитическими энзимами, необходимыми для расщепления ос-
новных компонентов водорослей. Первичное расщепление происходит внекле-.
точно. Фагоцитоз и внутриклеточное переваривание не наблюдаются. Всасы-
вание растворенных пищевых веществ может встречаться наиболее вероятно в
срехней кишке или в эпителии, выстилающем внутренность желудка.

MALACOLOGIA, 1969, 9(2): 501-508

ISOENZYMES OF ALKALINE PHOSPHATASE IN ANODONTA
GRANDIS (BIVALVIA: UNIONIDAE) DURING SHELL
REGENERATION 1

А. $. М. Saleuddin?

Department af Zoology, University of Alberta, Edmonton, Alberta, Canada

ABSTRACT

The isoenzymes of alkaline phosphatase of the freshwater mussel Anodonta grandis
Say have been separated electrophoretically on cellulose acetate strips. In normal speci-
mens 3 isoenzymes were detected in the mantle, the digestive diverticula and the kidney
each. In specimens part of whose shells had been removed an additional band appeared

in the mantle.

The total enzyme activity was estimated in all 3 tissues of normal specimens and was
greatest in the kidney. During shell regeneration increase of the enzyme in the mantle
was twofold whereas that in the digestive diverticula was only slight. From histological
evidence, the digestive diverticula and the stomach seem the probable sources of enzyme
increase in the mantle, though the kidney should not be excluded.

INTRODUCTION

The diverse sites of alkaline phospha-
tase activity in vertebrate and inverte-
brate tissues indicate that this enzyme
may be important in several different
functions. The enzyme has been impli-
cated in the secretion of protein fibres,
synthesis of mucoproteins, ossification
and cellular differentiation. Alkaline
phosphatase is among the many enzymes
which occur in multimolecular forms, i.e.,
as isoenzymes. The number has been
varyingly reported as 3 (Keiding, 1959), 4
(Chiandussi, Green & Sherlock, 1962), 8
(Taswell & Jeffers, 1963) and 16 (Boyer,
1961).

Information about the isoenzymes of
alkaline phosphatase in molluscs is very
scanty. Norris & Morril (1964) electro-
phoretically separated 4 isoenzymes from
the digestive diverticula (liver) and 2
from the mantle of Lymnaea palustris.

In the developing embryo of //yanassa
obsoleta, Morril & Norris (1965) found 1
band which appeared on the 7th day.
Alkaline phosphatase has been asso-
ciated directly or indirectly with mol-
luscan shell formation. Increase of en-
zyme activity has been recorded during
shell regeneration in Helix (Manigault,
1939; Wagge. 1951). After removal of a
piece of shell, I found a great increase of
this enzyme in the mantle of Anodonta in
the vicinity only of the shell injury (Sale-
uddin, 1967). However, no quantitative
estimation of the amount present in the
tissues of either normal or injured speci-
mens were then made. In the present
investigation an attempt has been made
to quantitatively determine enzyme activ-
ity in the digestive diverticula and in the
mantle with and without shell injuries:
enzymic assay with kidney tissue was
done using only normal specimens. 150-
enzymes of alkaline phosphatase have

1 This work was carried out during the tenure of a post-doctorate fellowship from the National Research

Council of Canada.

2 Present address: Department of Biology, York University, Toronto, Ontario, Canada.

502 A. S. M. SALEUDDIN

been separated electrophoretically on cel-
lulose acetate membranes and the changes
brought about by shell injuries in the
number and relative concentration of
isoenzymes have been recorded.

MATERIALS AND METHODS

Specimens of Anodonta grandis were
collected from Lake Wabamun, 45 miles
west of Edmonton, Alberta, Canada, and
maintained in running water at 15°C.
Shell regeneration was induced by remov-
ing about 25 sq. mm of shell from the
ventral edge of the left valve with an
electric saw. Care was taken so as not
to injure the underlying mantle. Tissues
were removed 1, 4 and 8 days after shell
injury. Tissue homogenates of the man-
tle, digestive diverticula and kidney were
prepared in the following manner. Fresh
tissues were frozen quickly in an acetone-
dry ice mixture. They were then removed
and pulverized while frozen, suspended
in 0°6M sucrose solution (1 ml of sucrose
solution per 600 mg of tissue) and homo-
genized. In order to activate the release
of bound enzyme, n-butanol was added
to the homogenate in the proportion of
1:10 by volume. The mixture was stirred
for 10 minutes and then centrifuged at
13,000 X g for 10 minutes. The butanol
was removed from the top of the super-
natant by suction and the rest of the
supernatant was stored at —20°C until
needed. During this entire process the
temperature was not allowed to rise above
4°С.

Electrophoresis was carried out оп
cellulose acetate strips using a Beckman
Microzone Model R-101 apparatus. Bar-
bital buffer of pH 8°6 and ionic strength
0:05 was used. Samples of 0°5 pl of
homogenate were applied to the middle
of the membrane and run for 1 1/2 hr at
250 volts at an ambient temperature of
4°C. The strip was then fixed in abso-
lute ethanol for 1-2 minutes. Excess

- 1
ma ki dd
FIG. 1. Electrophoretic separation of isoenzy-

mes Of alkaline phosphatase from tissue extracts
of unin jured Anodonta grandis on cellulose
acetate strips. ma, mantle; ki, kidrey; dd,
digestive diverticula, o =0rigin,—=cathode,
1, 3, 4, stained isoenzymes.

ethanol was removed by draining, and
the strip was stained for alkaline phos-
phatase for | hour, following the staining
procedure of Burstone (1958). The stain-
ing solution was prepared by first mixing
thoroughly | ml N-N-dimethylformamide
and 20 mg naphthol phosphate AS-TR.
To this mixture 100 ml of tris buffer,
pH 8:3, and 50; mg of Fast Ве
(5-chloro-o-toluidine) were added. The
solution was filtered and 2 or 3 crystals
of MgCl, were added to the filtrate.
After staining and drying, the optical
density of the strip was scanned with a
densitometer (model 525 of Photovolt
Corporation, New York).

The method of Klein, Read & Babson
(1960) was followed for the quantitative
assay of alkaline phosphatase. This
method has been elaborated by Warner-
Chilcott Laboratories, Morris Plains, N.J.
A volume of 0:2 ml homogenate was
incubated for 30 minutes at 37°C with
sodium phenolphthalein phosphate in tris
buffer of pH 9°6. Micrograms of phe-
nolphthalein liberated were read at 550
my. with a Bausch and Lomb Spectronic

ALKALINE PHOSPHATASE IN ANODONTA 503

DIGESTIVE
DIVERTICULA

Normal

20 colorimeter, and were converted into
King-Armstrong units by using a con-
version table (Bulletin of Warner-Chilcott
for colorimetric assay of alkaline phos-
phatase).

RESULTS

In normal specimens of Anodonta
grandis 3 isoenzymes of alkaline phos-
phatase represented by 3 distinct bands
(1, 3, 4, Figs. 1, 2) were present in the
mantle, digestive diverticula and kidney
each. All migrated toward the cathode.
In all 3 tissues, band 4 was the most pro-
minent but showed a slight difference in
electrophoretic mobility. Bands l and 3,
however, showed similar migration in all
tissue extracts (Figs. | and 2).

The total enzyme activity in the mantle,
digestive diverticula and kidney of normal
mussels are 13. 28 and 33 King-Armstrong
units respectively (Table 1).

In regenerating specimens the change
in enzyme has been followed in the mantle
and digestive diverticula only. The iso-
enzyme patterns, during regeneration are
shown in Fig. 2. After 24 hours, bands
| and 4 of the mantle increase in pro-
minence while 3 remains unchanged.
Band 2 which appeared close to band |
became indistinguishable at 4 days for
reasons unknown, only to reappear on
the 8th day of regeneration. The isoen-
zymes of the digestive diverticula showed
only a slight increase in intensity during
shell regeneration.

In regenerating mussels the total en-
zyme activity in the mantle tissue in-
creased more than twofold at 24 hours,
showed further increase at 4 days, and
had returned toward normal at 8 days.
In the digestive diverticula enzyme activ-
ity did not change markedly (Table 1).

FIG. 2. Densitometric tracings of electropho-
retic pattern shown in Fig. 1. Peaks of curves
correspond to bands.

504 А. 5. М. SALEUDDIN

TABLE 1. Total alkaline phosphatase found in 3 organs of Anodonta grandis with and without shell
injuries, expressed in King-Armstrong units. The figures represent average values followed

by standard deviations.

After injury

TISSUES | Normal Г = : ——
| 24 hrs. 4 days 8 days
Mantle 1340-669 3241-53 35+1-417 170-816
Digestive diverticula | 28-40-816 3441-635 30+1-532 28+1-052
Kidney | 3340-823 —_ a dE

—Not Measuicu.

DISCUSSION

The isoenzymes of alkaline phosphatase
in the mantle, digestive diverticula and
kidney of Anodonta grandis moved toward
the cathode. However the direction of
the movement can be changed by chang-
ing buffer pH and ionic strength or by
changing placement of the sample on the
strip. Latner & Raine (1962) reported
that the positions of the isoenzymes of
human serum alkaline phosphatase in
relation to major serum proteins can be
altered by using a discontinuous buffer
system.

The number of isoenzymes in all 3
tissues of Anodonta was 3, whereas Norris
& Morril (1964), using Lymnaea palustris,
found 4 in the digestive diverticula
(liver) and 2 in the mantle. In the
embryo of Ilyanassa obsoleta, Morril &
Norris (1965) found 1 band; they did not
mention adult tissues. During the shell
regeneration of Anodonta, an additional
band appeared in the mantle within
24 hours. Наце & de Jong (referred to
by Wilkinson, 1966) found that an addi-
tional alkaline phosphatase isoenzyme
appeared in human serum when the intes-
tine was damaged by radiation.

When a piece of shell is removed from
Anodonta, the regenerating area is covered

by a thin organic layer within 24 hours,
but calcification is not observed until
8 days after shell injury (Saleuddin, 1967).
Alkaline phosphatase has been reported
in tissues such as mantle and bone, in-
volved in calcification. Neuman, Diste-
feno & Mulryan (1951) proposed the
theory that this enzyme may aid calcifi-
cation by removing the crystal poisons
or inhibitors which would otherwise inter-
rupt the growth of crystals. In reviewing
this theory, Simkiss (1964) was unable to
draw definite conclusions in that alkaline
phosphatase does remove crystal poisons
by hydrolysis but some products of hydro-
lysis, such as orthophosphate, inhibit
calcification. In A. grandis the increase
of enzyme in the mantle of injured speci-
mens does not correspond to the period
of calcification, but to the elaboration of
the organic layer when calcium deposition
is not yet taking place. The enzyme
increase in the mantle is much greater
than that observed in the digestive diver-
ticula (Table 1). The sources of this
increase are probably the main ducts of
the digestive diverticula and the stomach.
Both histological and histochemical evid-
ence seem to support this view: there is
an increase of the enzyme activity in the
brush border area of the main ducts of
the digestive diverticula 24 hours after

ALKALINE PHOSPHATASE IN ANODONTA 505 .

DIGESTIVE DIVERTICULA

4 days

FIG. 3. Electrophoretic separation of isoenzymes of alkaline phosphatase from tissue extracts of
Anodonta grandis at various times during shell regeneration. ma, mantle: dd, digestive diverticula; о,
origin; — =cathode. Note the appearance of band 2 in mantle only.

FIG. 4. Densitometric tracings of electrophoretic patterns shown in Fig. 3.

506 А. S. М. SALEUDDIN

shell injury. This increase is accom-
panied by aggregation of blood cells stain-
ing positively for alkaline phosphatase in
the blood spaces of the digestive diverti-
cula. A similar situation is also observed
in the vicinity of the stomach. These
blood cells are presumably taking active
part in transporting the enzyme to the
mantle, since a marked increase in the
number of such positively staining blood
cells has also been observed in the mantle.
If we accept the digestive diverticula as
the main source for the increase of enzyme
in the mantle during regeneration one
would expect identical electrophoretic
migration of the isoenzymes in these 2
tissues; but this is not the case (Figs. 3
& 4). It might be that the enzyme is
altered when released for the digestive
diverticula and during the transportation
to the mantle. Examples of such altera-
tions are known. Keiding (1964) men-
tions that the transformation of human
В. lymph phosphatase into a, bile phos-
phatase is probable. Butterworth, ef al.
(1965). while working on urine phospha-
tase, found that the enzyme fraction from
urine moved faster than that from the
kidney and suggested that the enzyme is
altered in urine after release from the
kidney. Nevertheless. the kidney and
intestine of Anodonta should not be
excluded as possible sources for the
increase of enzyme in the mantle during
shell regeneration.

LITERATURE: CITED

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BUTTERWORTE Р. Is, MOSS) DW. РМ
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CHIANDUSSI, L., GREEN, S. F. & SHER-
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———-— 1964, The alkaline phosphatase frac-
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MORRIL, J. B. & NORRIS, E., 1965, Electro-
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SIMKISS, K., 1964, Phosphates as crystal poisons
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TASWELL, H. F. & JEFFERS, M. T., 1963,
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WAGGE, L. E., 1951, The activity of amoebo-
cytes and of alkaline phosphatases during the

regeneration of the shell in the snail Helix
aspersa. Quart. J. micr. Sci., 92: 307-321.

WILKINSON, J. H., 1966, Isoenzymes. J. P.
Lippincott, Philadelphia.

ALKALINE PHOSPHATASE IN ANODONTA

RESUME

ISOENZYMES DE LA PHOSPHATASE ALCALINE CHEZ ANODONTA
GRANDIS (BIVALVIA: UNIONIDAE)

A.S. M. Saleuddin

Les isoenzymes de la phosphatase alcaline du bivalve d'eau douce Anodonta grandis
Say ont été separées par électrophorese sur bandes d'acétate de cellulose. Chez les exem-
plaires normaux, 3 iscenzymes ont été détectées dans le manteau, les diverticules digestifs
et le rein. Chez lés exemplaires dont les coquilles avaient été enlevées, une bande
supplémentaire est apparue pour le manteau.

L’activité enzymatique totale a été testée pour les trois tissus sur des individus normaux
et s’est montrée plus importante dans le rein. Pendant la régénération de la coquille,
l’augmentation d'enzyme dans le manteau a été double, tandis que dans les diverticules
digestifs l'augmentation a été faible. Si Pon s’en réfère à l’histologie, les diverticules
digestifs et Pestomac semblent être les sources probables de l’augmentation d’enzyme
dans le manteau, bien que le rein ne doive pas étre exclu.

ASL:

RESUMEN

ISOENZIMAS DE FOSFATASA ALCALINA EN ANODONTA GRANDIS
(BIVALVIA: UNIONIDAE) DURANTE LA REGENERACION DE LA CONCHA

A.S.M. Saleuddin

Las isoenzimas del epigrafe en la almeja de agua dulce Anodonta grandis fueron
separadas electro-foréticamente en tiras de acetato de celulosa. En ejemplares normales
se detectaron 3 isoenzimas en el manto, divertículos digestivos y riñones; en otros, parte
de cuyas conchillas fueron quitadas, una banda adicional apareció en el manto.

La actividad enzimática total se calculó en los tres tejidos de ejemplares normales y
fué mayor en los riñones. Durante regeneración de la concha, la cantidad de enzima
en el manto fué doble, mientras que en los divertículos digestivos aumentó poco. Hay
evidencia histológica de que esos divertículos, y el estómago, puedan ser las fuentes
principales de aumento enzimático en el manto, aunque el riñon no debe exluirse de esta
consideración.

507

508 А. 5. М. SALEUDDIN
АБСТРАКТ

ИЗОЭНЗИМЫ ЩЕЛОЧНОЙ ФОСФАТАЗЫ У ANODONTA GRANDIS
(BIVALVIA: UNIONIDAE) ВО ВРЕМЯ РЕГЕНЕРАЦИИ РАКОВИНЫ

А. С. САЛЕУДДИН

Изоэнзимы щелочной фосфатазы у пресноводного моллюска Anodonta grandis Say
были выделены электрофоретически на целлюлозную ацетатную ленту. У обыч-
ных экземпляров моллюсков были обнаружены 3 изоэнзима: в мантии, в пицще-
варительной дивертикуле и в почке. У тех экземпляров, у которых раковина
была удалена, в мантии были обнаружены они добавочно.

Общая активность энзимов была определена во всех трех тканях нормаль-
ных экземпляров моллюсков и наиболее высокой была в почке. Во время ре-
генерации раковины количество энзимов в мантии возрастало в 2 раза, в то
время, как в пищеварительной дивертикуле оно увеличивалось лишь слабо.

Судя по гистологическим данным, пищеварительная дивертикула, желудок,
а возможно, и почка, являются вероятным источником увеличения энзимов в
мантии.

INDEX TO SCIENTIFIC NAMES

aciculata, Ocenebra, 384
Acteon, 421
adunca, Crepidula, 376
Aeolidia, 422
papillosa, 422
Agriolimax, 391, 92. 94, 95, 97-99
reticulatus, 391, 92, 94, 95, 97-99
alba, Gymnodoris, 438
albopunctata, Doriopsilla, 435
albopustulosa, Chron:odoris, 423
alderi, Eolidina, 422
amplecta, Lymnaea, 313, 17, 19, 21
Anodonta, 501-06
grandis, 501-05
apiculata, Halgerda, 423
appressa, Lymnaea stagnalis, 327
Archidordinae, 423
Archidoris, 423
hawaiiensis, 423
nubilosa, 423
Argobuccinum, 355, 84
oregonense, 355, 84
Arion, 398, 47]
ater, 471
Asternotus, 425
cespitosus, 423
ater, Arion, 471
aureomarginatus, Hexabranchus, 423
Australorbis, 327, 98
glabratus, 398
balthica, Масото, 491
banatica, Congeria, 322
bicolor, Gymnodoris, 438, 40
Biomphalaria, 327, 29, 31, 32, 36, 39, 41, 42, 45,
46, 99
glabrata, 327, 29, 31, 32, 36, 39, 41, 42, 45, 46
Blaberus, cranifer, 482
Buccinum, undatum, 477
Bursa, 349, 51, 52, 54-63, 66-68, 76, 82-85
caelata, 351
californica, 351
corrugata, 349, 51, 52, 54-63, 66-68, 76, 82-85
granifera, 351
granularis, 351
gyrina, 351
spinosa, 355
Busycon, 469
caelata, Bursa, 351
californica, Bursa, 351
Calliostoma, 398
ligatum, 398
cancellata, Chione, 351
Cardita, 351
floridana, 351
Carminodoris, 423

grandiflora, 423
nodulosa, 423
catinus, Velutinellus, 313, 16, 17, 19-21
caudata, Eupleura, 443
Cepaea, 398
nemoralis, 398
Cerithiopsis, 437
tubercularis, 437
cespitosus, Asternotus, 423
Chione, 351
cancellata, 351
Chlorella, 351
Chromodoridinae, 423
Chromodoris, 423, 24, 26
albopustulosa, 423
decora, 423, 24, 26
geometrica, 423
imperialis, 423
lilacina, 423
petechialis, 423
trimarginata, 423
youngbleuthi, 423
cinerea, Urosalpinx, 443
citrina, Gymnodoris, 438, 39
clathrata, Distorsio. 349, 51, 68-70, 72, 73, 75, 77.
79, 81, 83-86
Codakia, 351
orbicularis, 351
codapavonis, Velutinopsis, 313, 15, 16, 19
Congeria, 315, 17, 22
banatica, 322
digitifera, 315
politionaei, 322
ramphophora, 317, 22
soceni. 322
corniculum, Nassarius. 468
corrugata, Bursa, 349, 51, 52, 54-63, 66-68, 76, 82-85
Coryphella, 382
cranifer, Blaberus, 482
Cratena, 422
glotensis, 422
Crepidula, 350, 56, 64, 74, 404
adunca, 376
fornicata, 356
croatica, Radix, 320, 21
Cyclope, 470
neritea, 470
Cylichna, 421, 22, 29, 32
Cymatilesta, 384
spengleri, 384
Cymatium, 386
daniellae, Hypselodoris, 423
decora, Chromodoris, 423, 24, 26
Dendrodorididae, 42/
Deroceras, 391, 98

INDEX TO SCIENTIFIC NAMES

reticulatus, 391, 98
Dendrodoris, 433-38

nigra, 433-37

limbata, 436
Diaululinae, 423
Didacna, 315

otiophora, 315
digitifera, Congeria, 315
Discodoridinae, 423
Discodoris, 423

fragilis, 423
Distorsio, 349, 51, 68-70, 72, 73, 75, 77, 79-81,

83-86

clathrata, 349, 51, 68-70, 72, 73, 75, 77, 79-81,

83-86

Dolium, 382
Doridacea, 434, 38
Dorididae, 423
Doridinae, 423
Doridopsis, 434, 36

nigra, 434

limbata, 436
Doriopsilla, 435, 436

albopunctata, 435
Doriopsis, 423, 24, 26

granulosa, 423, 24, 26

nucleola, 423

pecten, 423

viridis, 423
Dosinia, 313,15, 17, 20, 21

maeotica, 315, 17, 21
Drosophilia, 336

melanogaster, 336
drummondi, Facelina, 422
dura, Halichondria, 435
Dunaliella, 351, 68

tertiolecta, 351
echinata, Trippa, 423
elegens, Okadaia, 442, 43
Eolidina, 422

alderi, 422

Eupleura, 443

caudata, 443
Facelina, 422

drummondi, 422
fellowsi, Peltodoris, 423
Fissurellidae, 432
flavus, Limax, 399
floridana, Cardita, 351
formosa, Platydoris, 423
fornicata, Crepidula, 356
fragilis, Discodoris, 423
Fulgur, 385
galbana, Isochrysis, 411
Gastropoda, 349, 50, 55, 447, 87
geometrica, Chromodoris, 423
geticus, Ninia, 315

geticus, Theodoxus, 315
gigas, Strombus, 403, 15
glabrata, Biomphalaria, 327, 29, 31, 32, 36, 39, 41,
42, 45, 46
glabratus, Australorbis, 398
glotensis, Cratena, 422
Goniodorididae, 422
grandiflora, Carminodoris, 423
grandis, Anodonta, 501, 02-05
granifera, Bursa, 351
granifera, Ranella, 351
granularis, Bursa, 351
granulosa, Doriopsis, 423, 24, 26
graphica, Halgerda, 423, 25, 30
Gymnodoridinae, 438
Gymnodoris, 438-40, 42
alba, 428
bicolor, 438, 40
citrina, 438, 39
okinawae, 438-40
plebeia, 438
Crptochiton, stelleri, 493
gyrina, Bursa, 351
gyrina, Physa, 327, 36
gyrina, Ranella, 351
haemastoma, Thais, 383
Halgerda, 423, 25, 30
apiculata, 423
graphica. 423, 25, 30
rubra, 423
Halgerdinae, 423
Halichondria, 435
dura, 435
Haliotus, 350
hawaiiensis, Archidoris, 423
Helix, 471, 77, 83, 93, 501
Hexabranchidae, 423
Hexabranchus, 423, 29
aureomarginatus, 423
marginatus. 423 25, 29
pulchellus, 423
hilaris, Thordisa, 423, 29
Hydrobia, 491
ulvae, 491
Hypselodoris, 423, 29
daniellae, 473
kayae, 425
lineata, 423
peasei, 423
vibrata, 423, 29
lanthina, 442
Ilyanassa, 385, 448, 501
obsoleta, 501
imperialis, Chromodoris, 423
incrassatus, Nassarius, 468
Isochrysis, 411
galbana, 411

INDEX TO SCIENTIFIC NAMES

Jorunna, 422, 23, 27, 50
tomentosa 422, 23, 27, 30
kayae, Hypselodoris, 423
Kentrodoridinae, 423
lapillus, Nucella, 477
lapillus, Purpura, 384
ligatum, Calliostoma, 398
lilacina, Chromodoris, 423
Limax, 398, 99
flavus, 399
maximus, 399
tenellus, 398
timbata, Dendrodoris, 436
limbata, Doridopsis, 436
Limnocardium, 315
zagrabiense, 315
lineata, Hypselodoris, 423
Littorina, 350, 98, 403, 04, 06, 09, 11, 13-16, 69,
85, 94
picta, 403, 04, 06, 09, 11, 13-16
scutulata, 398
lutheri, Monochrysis, 411
Lymnaea, 313, 17, 19, 21, 27, 99, 501, 04
amplecta, 313, 17, 19, 21
palustris, 501, 04
peregra, 327
stagnalis appressa, 327
velutina, 314
Lymnaeidae, 3/3

Macoma, 491
balthica, 491
maeotica, Dosinia, 315, 17, 21
mansoni, Schistosoma, 327
marginatus, Hexabranchus, 423, 25, 29
maximus, Limax, 399
melanogaster, Drosophilia, 336
Mesogastropoda. 489
Modiolus, 485
Monochrysis. 411
lutheri, 411
Murex, 469
Muricidae, 443
Mya, 485
myosotis, Ovatella, 398
Mytilus, 485
Nassa, 350
Nassarius, 403, 04, 11, 15, 16, 47-49, 51, 61, 63,
68-71, 75, 77, 80-94
corniculum, 468
incrassatus, 468

obsoletus, 403, 16, 47-49, 51, 63, 69-71, 75, 77,

80-94
reticulatus, 449, 61, 62, 70
vibex, 403
Naticidae, 443
nemoralis, Сераеа, 298
Nereis, 485

neritea, Cyclope, 470
nigra, Dendrodoris, 433-37
nigra, Doridopsis, 434
Ninia, 315

geticus, 315
nobilis, Velutinopsis, 321
nodulosa, Carminodoris, 423
nubilosa, Archidoris, 423
Nucella, 477

lapillus, 477
nucleola, Doriopsis, 423
Nudibranchia, 42/, 22
obsoleta, Ilvanassa, 501
obsoletus, Nassarius,403, 16, 47-49, 51, 63, 69-7]

75, 77, 80-94

Ocenebra, 384

aciculata, 384
Okadaia, 442, 43
elegens, 442, 43
Okeniidae, 422
okinawae, Gymnodoris, 438, 39, 40
Onchidorididae, 422
Oncomelania, 327, 29
orbicularis, Codakia, 351
oregonense, Argobuccinum, 355, 84
osseosa, Trippa, 423
otiophora, Didacna, 315
Ovatella, 398
myosotis, 398
palustris, Lymnaea 501, 04
papillosa, Aeolidia, 422
Paradacna, 315
Patella, 350
peasei, Hypselodoris, 423
pecten, Doriopsis, 423
Peltodoris, 423
fellowsi, 423
Penaeus, 485
peregra, Lymnaea, 327
perversa, Triphora, 437
petechialis, Chromccoris, 423
Phaeodactylum, 403, 06, 11, 14, 15
tricornutum, 403, 06, 11, 14, 15
Philine, 421; 22, 26, 30, 32, 34, 37, 42
Physa, 327, 36
gyrina, 327, 36
picta, Littorina, 403, 04, 06, 09, 11, 13-16
Pila, 364
pilleus, Velutinellus, 313, 16, 17, 20, 21
Platydoridinae, 423
Platydoris. 423
formosa, 423
Platymonas, 351, 68, 415
plebeia, Gymnodoris, 438
politioanei, Congeria, 322
Polyceridae, 421, 22, 38
Polycerinae, 422

INDEX TO SCIENTIFIC NAMES

Pomatias, 350 Thordisa, 423, 29
Prosobranchia,, 448 hilaris, 423, 29
Proralenciennesia, 313, 21, 22 setosa, 423
pulchellus, Hexabranchus, 423 tomentosa, Jorunna, 422, 22, 23, 27, 30
Purpura, 384 Tonna, 283
lapillus, 384 transiens, Velutinopsis, 313, 17, 21
uate, E ПРЕ tricornutum. Phaeodactylum, 403, 06, 11, 14, 15
croatica, 320, 21 irtmarginata, Chromcdoris, 423
kobelti, 320 Triphora, 437
velutina, 314 perversa, 437
ramphophora, Congeria, 317, 22 Trippa, 423
Ranella, 351 echinata, 423
granifera, 351 osseosa, 423
gyrina, 351 scabriuscula, 423
reticulatus, Agriolimax, 391, 92, 94, 95, 97-99 Тиррипае, 423
reticulatus, Deroceras, 391, 98 tubercularis, Cerithiopsis, 437
reticulatus, Nassarius, 449, 61, 68, 70 Ulva, 485
Retusa, 421, 37, 38 ulvae, Hydrobia, 491
rubra, Halgerda, 423 undatum, Buccinum, 477
rugosa, Velutinopsis, 313, 17, 21 Undulotheca, 313, 20, 22
Scaphander, 421 Unio, 315, 17
scabriuscula, Trippa, 423 subrecurvus, 315, 17
Schistosoma, 327 Unionidae, 50/
mansoni, 327 Urosalpinx, 443
scutulata, Littorina, 398 cinerea, 443
Semifusus, 469 Valenciennius, 313-15, 17, 20-22
setosa, Thordisa, 423 Vayssiereidae. 442
soceni, Congeria, 322 velutina, Lymnaea, 314
spengleri, Cymatilesta, 384 velutina, Radix, 314
spinosa, Bursa, 355 velutina, Velutinopsis. 313, 14, 17, 19, 21
Squilla, 485 Velutinellus. 313, 14, 16, 17, 19-22
stagnalis appressa, Lymnaea, 327 catinus, 313, 16, 17, 19-21
stelleri, Cryptochiton, 493 pilleus, 313, 16 17, 19-21
Strombus, 403, 15 rugosus, 313, 20, 21
gigas, 403, 15 Velutinopsis, 313-17, 19-22
subatava, Teisseyreomya. 317 codapavonis 313, 15, 16, 19, 20
subrecurvus, Unio, 315, 71 nobilis, 321
Teisseyreomya, 315, 17, 19 rugosa, 313, 17, 21
subatava, 317 transiens, 313, 17, 21
tenellus, Limax, 398 velutina, 313, 14, 17, 19-22
tertiolecta, Dunaliella, 351 vibex, Nassarius, 403
Testacella, 442 vibrata, Hypselodoris, 423, 29
Thais, 350, 83, 84 viridis, Doriopsis, 423
haemastoma, 383, 84 Viviparus, 350, 432
Theodoxus, 315 youngbleuthi, Chromodoris, 423

geticus, 315 zagrabiense, Limnocardium, 315

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Washington, D.C. 20036, U.S.A. En particulier, cn préconise des simplifications telles que celles-ci:
les nombres ne devront pas étre écrits en lettres, sauf au début des phrases; les pourcentages suivant un
nombre seront exprimés par le signe %; les abréviations de m sures (aprés un numbre): mm, ml, kg, etc
n’auront ni point, ni “ s”” au pluriel.

Les illustrations doivent être soigneusement exécutées et de proportions telles qu'elles puissent être
rapportées à la justification d’une colonne ou d’une page de la revue. La taille maximale d'une figure
imprimée est de 13,520 cm. Les grandes illustrations seront accompagnées d'une plus petite photo
pour les éditerurs. Le trait et la lettre doivent être à l’encre de chine noire ou au carbone noir sur papier
blanc ou sur papier calque. La graphie sera suffisamment grande pour supporter la réduction d’un demi
ou d'un tiers. Ceci devra être pris en considération en particulier en ce qui concerne la lettre. Les lettres
et les nombres ne doivent pas avoir moins de | mm de haut aprés réduction et seront de préférence plus
grands. Un certain nombre de dessins ou de photographies peuvent trés bein être groupés pour former
une page.

Bibliographie. Voir les numéros récents de MALACOLOGIA pour connaitre la forme désirée des
citations. En particulier, on notera que la revue utilise 1’ et commercial (&); “et al ” peut être utilisé
dans le texte, mais non dans la liste des références; еп plus du numéro du volume. il faut citer la lére et
derniére page des articles et des livres; pour les livres citer aussi l’editeur et la ville d'édition.

Separata. Les auteurs recevront 50 tirés-à-part gratuitement, d’autres exemplaires peuvent être obtenus
au prix coutant s’ils sont commandés au moment du renvoi des épreuves. Des commandes plus tardives
ne peuvent être prises en consideration.

Correspondance. Tous les manuscrits et les figures, aussi bien que les paiements et les demandes de
renseignements et de souscriptions, doivent être envoyés directement a C. J. Bayne, Managing Editor,
Muséum of Zoology, The University of Michigan, Ann Arbor, Michigan 48104, U S.A.

INSTRUCCIONES PARA AUTORES

MALACOLOGIA publicara trabajos originales, descriptivos о de carácter experimental, dedicados
primaria o exclusivamente al estudio de los Moluscos. Los artículos deberán ser inéditos y pueden con-
stituir monografías extensas O revisiones comprensivas, así como trabajos cortos de investigacion, pero
notas abreviadas no son aceptables. MALACOLOGIA intenta ofrecer un medio comun para los
differentes aspectos de la Malacología, como anatomía, ecología, malacología médica, paleontología,
fisiología y taxonomía. La revista mantendrá un nivel estrictamente científico, y todos los manuscritos
seran revisados por dos editores.

Los manuscritos deberán ser en inglés, frances, castellano, alemán o ruso, deberán ajustarse al estilo
de la revista, y contener un conciso pero adecuado sumario para traduccion en los otros idiomas. Deberán
ser escritos a máquina con original y una copia en carbonico, con doble espacio, y margenesarriba y a la
izquierda de 3 cm por lo menos.

Las contribuciones en inglés deberán seguir las recomendaciones del Style Manual for Biological Journals
obtenible en el Institute of Biological Sciences, 2000 P Street, N.W., Washington D.C. 20036, U.S.A.
En particular se prefieren practicas simples, como las siguientes: los numeros no deberán escribirse en
letras al menos que sea al principio de la frase: porcentajes expresados como %; abreviaciones de medidas
(despues de numero) mm, ml, kg, etc. sin punto o sin S en el plural.

Las ilustraciones deben ser prolijas y planeadas de manera que puedan imprimirse como figuras del
ancho de una columna o del ancho total de la pagina de la revista. El tamano maximo para una figura
impresa es de 13,520 cm. Ilustraciones grandes deberán acompanarse de una foto reducida para los
editores. Dibujos y letras en tinta china negra, o negro de carbon sobre fondo blanco. Los cuadros
suficientemente grandes como para poder reducirlos nitidamente a la mitad o un tercio; esto deberá ser
considerado especialmente en relacion a las letras. Letras y numeros, después de reducidos, no deberán
ser menores de I cm, y mejor aun si algo mas grandes. Diversos dibujos o fotos podrán agruparse con-
venientemente para ajustarse a una página.

Referencias: Véase un numero corriente de la revista para la forma deseada en las citas. Particular-
mente, se notará que la revista usa el signo & en lugar de “and” o “y”; “et al” podra usarse en el
texto pero no en la lista final de referencias; deberán citarse ademas, las páginas completas de los artículos
y libros, y el editor y ciudad para los libros.

Separados: Los autores recibirán 50 separados gratis, ejemplares adicionales podran obtenerse al costo,
si se ordenan al tiempo de devolver las pruebas; ordenes recibidas más tarde no podrán ser considera
radas.

Correspondencia: Todos los manuscritos y figuras, así como pedidos de subscripcion, y pagos deberán
remitirse al C. J. Bayne, Managing Editor, Museum of Zoology, The University of Michigan, Ann Arbor,
Michigan 48104, U.S.A.

К СВЕДЕНИЮ АВТОРОВ

МАЛАКОЛОГИЯ опубликует результаты оригинальных работ описазельного или эксперименталь-
ного характера, посвященных в первую очередь или исключительно изучению моллюсков. Статьи
не должны публиковаться или быть уже опубликованы ни в каком другом месте. Работы могут
представлять собой более пространные монографии или ревью-разборы, а также короткие иссле-
довательские сообщения, однако короткие заметки не принимаются. Журнал ставит своей целью
постижение общей атмосферы для таких разных областей малакологии как анатомия, экология,
медицинская малакология, палеонтология, физиология и таксономия. Особой заботой журнала
является поддержание высокого научного уровня. Все рукописи подлежат рассмотрению по край-
ней мере двух редакторов.

РУКОПИСИ могут быть представлены на английском, Французском, немецком, русском или ис-
панском языках и должны придерживаться стиля журнала МАЛАКОЛОГИЯ. Они должны включать аб-
стракт в краткой, но полной форме для перевода на другие языки. Рукопись должна быть отпе-
чазана через строчку с полями не меньше 3 см по левой и верхней стороне листа и должна
быть представлена в двух экземплярах (копия на тонкой бумаге).

Для авторов, пишущих на английском языке, мы советуем слеловать правилам изложенным в
"руководстве по стилю для биологических журналов" (Style Manual for Biological Journals), которое мо-
жно приобрести в Американском Институте Биологических Hayk,American Institute of Biological Sciences,
2000 P Street, М. W., Washington, D.C. 20036, U.S.A. Особенно полезны такие правила упрощения, как:
численное значение должно быть дано в цифрах, если оно не стоит в начале предложения; про-
центы, следующие за численным значением обозначаются значком %; сокращения в наименованиях
мер (после числа) мм, мл, кги т.д. пишутся без точки после них.

ИЛЛЮСТРАЦИИ должны быть тщалельно выполнены и размещены зак, чтобы они могли быть напе-
чатаны по ширине колонки или в полную ширину журнального листа. Наибольший размер напеча-
танного рисунка составляет 13,5 х 20 см. Крупные рисунки должны сопровождаться фотографией
меньшего размера для редактора. Рисунки и надписи полжны быть выполнены или черной тушью
или угольно-черной печатью на белой с голубой разлиновкой бумаге. Таблицы должны быть по-
вольно крупными, чтобы выдержать уменьшение Ha ‘половину или на одну треть. Это особенно
важно в отношении надписей. Буквы и цифры должны быть не меньше 1 мм в высоту, предпочти-
тельно больше, после уменьшения. Очень часто несколько рисунков и фотографий могут быть
сгруппированы вместе, чтобы уместиться на одной странице.

БИБЛИОГРАФИЯ. Для желательной формы ссылок смотри текущий выпуск МАЛАКОЛОГИИ. Кроме
указания номера выпуска или тома должно быть сообщено полное количество страниц в статье
или книге, а в случае ссылки на книгу лолжно быть указано издательство и город.

ОТДЕЛЬНЫЕ ОТТИСКИ. Авторы получают 50 бесплатных оттисков; дополнительные копии могут
быть приобретены по себестоимости, если заказ на них сделан не позже момента корректиро -
вания публикации. Заказы, поступившие после указанного срока, не принимаются.

ПЕРЕПИСКА. Все рукописи, рисунки, а также заказы на подписку, денежные переволы и пр.
полжны направляться по адресу заместителя главного редактора: С.Ф. Bayne, Museum of Zoology, The
University of Michigan, Ann Arbor, Michigan 48104, U.S.A.

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