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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... 


47 


53 


249 


hm 
un 


59 


254 


65 


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). . 


42 


43 


43 


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 


17 


+ 
я. 


cf 


3 
+ 
x 


+4 
e 


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 


vi 


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 


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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) 


10 


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. 


11 


12 


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 


13 


14 


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. 


1) 


2) 
3) 


4) 


5) 
6) 


7) 


8) 


=) 


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: 


1) 


2) 


3) 


4) 


5) 


6) 


7) 


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. 


15 


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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) 


18 


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. 


19 


20 


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. 


42 


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 


37 


39 


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. 


2) ay и 
Strains | Height Height of the aperture Biggest diameter 
—_——— — eco а SE = o | — s+ = 
North 6.7 4.2 4.6 
Portugal === | = = = 
South 9.0 5.2 5:5 
a = ae fol eee в : 2 en = an 
Tchad 8.1 | 549 528 
Egypt 8.5 5.5 5:5 
Liban | 8.1 | Dei 5.4 
en at ern = = 


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 - 

ee 


(*) 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, 


31 


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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. 


(37) 


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 | 


(39) 


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. 


(40) 


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. 


(42) 


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. 


(43) 


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 
a 
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 
auf die Bodenarten und Gewässer. 


Bemerkung: Die verschiedenen Zeichen kónnen auf den schwarzen Fláchen weiss erscheinen, 
sind aber dieselben. 


Für die häufigen Arten sind nur einige extreme Fundorte angegeben. 


> 
РУ, Lie À NOIR 
- pe A + 


Г gi 4 LEE 7 
N ‘bile 


в. 


р 7 


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. 


(59) 


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. ) 


61 


62 


FIGS. 7-10. 


PROC. THIRD EUROP. MALAC. CONGR. 


Various shapes of frontal organ with hooks. 


(See text. ) 


BINDER 63 


п 


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 


(65) 


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) 


74 


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 


vs 


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 


15 


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. 


(79) 


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 


(85) 


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. 


BIBLIOGRAPHY 


ALZONA, C. € BISACCHI, J., 1969, Malacofauna Italica. (In press). 

BISACCHI, J., 1929), Molluschi terrestri e fluviatili raccolti dal Marchese Giacomo 
Doria nell'Arcipelago toscano (1875-1901). Ann. Mus. Civ. St. Nat. Genova, 
53: 164-186. 

BÚTTNER, K., 1926, Beitráge zur Kenntnis der Land- und Siisswasserfauna Korsikas. 
5. Mollusca (ausschliesslich der Nacktschnecken). Mitt. Zool. Mus. Berlin, 
12(2): 235-240. 

CAZIOT, E., 1916, Note sur les Campylaea de la Sardaigne et des iles de Capraia, 
de Pianosa et de Corse. Bull. Soc. zool. France, 41: 65-76. 

COLOSI, G., 1920, Limacidi e Arionidi conservati nel R. Museo Zoologico di Firenze. 
Monit. Zool. Ital,, 31: 61-73. 

DE STEFANI, C., 1875, Molluschi viventi nella valle del Serchio superiore. Bull. 
Soc. Malacol. Ital., 1: 35-67. 

DE STEFANI, C., 1879, Nuovi molluschi viventi nell’Italia centrale. Bull. Soc. 
Malacol. Ital., 5: 38-48. 

DE STEFANI, C., 1883, Molluschi viventi nelle Alpi Apuane, nel Monte Pisano e 
nell’Appennino adiacente. Bull. Soc. Malacol. Ital., 9: 11-253, 1 tab. 

FORCART, L., 1965, Rezente Land- und Süsswassermollusken der stiditalienischen 
Landschaften Apulien, Basilicata und Calabrien. Verh. naturf. Ges. Basel, 
76(1): 59-194. 

FORCART, L., 1967, Die systematische Stellung toskanischer Oxychilus-Arten und 
Neubeschreibung von Oxychilus (Ortizius) lanzai п. sp. Arch. Molluskenk., 
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GERMAIN, L., 1930, Mollusques terrestres et fluviatiles. Faune de France, 21: 1-477, 
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GENTILUOMO, C., 1868, Catalogo dei molluschi terrestri e fluviatili della Toscana. 
Boll. Malacol. Ital., 1: 67-100. 

GIUSTI, F., 1968, Notulae Malacologicae UI. Il genere Oxychilus nell’Arcipelago 
toscano, con descrizione di un nuovo sottogenere e di quattro nuove specie: 
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п. sp., Oxychilus (s.str.) igilicus п. sp., ed Oxychilus (s.str.) argentaricus п. sp. 
Atti Soc. Tosc. Sci. Nat. 75, serie B: 218-235. 

GIUSTI, F., 1969, Notulae Malacologicae III. Sulla sistematica e distribuzione del 
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87-100. 


GIUSTI 91 


GIUSTI, F., 1968, Notulae Malacologicae IV. L/’isola di Montecristo e lo Scoglio 
d’Africa. Atti Soc. Tosc. Sc. Nat., 75, serie B: 239-254. 

GIUSTI, F., 1968, Notulae Malacologicae У. Le isole di Capraia, Gorgona e Giglio. 
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HESSE, P., 1932, Zur genaueren Kenntnis einiger italienischer Heliciden. Arch. 
Molluskenk., 64: 189-197, tab. 14, figs. 1-3. 

HOFFMANN, H., 1926, Beiträge zur Kenntnis der Land- und Süsswasserfauna Kor- 
sikas. 6. Die Nacktschnecken. Mitt. aus dem Zool. Mus. Berlin, 12(2): 241-262. 

ISSEL, A., 1866, Dei molluschi raccolti nella provincia di Pisa. Mem. Soc. Ital. 
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ISSEL, A., 1872, Appendice al catalogo dei molluschi raccolti nella provincia di Pisa. 
Atti Soc. Ital. Sci. Nat. Milano, 25: 58-76. 

ISSEL, A., (1873), Di alcuni molluschi raccolti nell’isola di Sardegna dal Dott. Gestro. 
Ann. Mus. Civ. St. Nat. Genova, 4: 275-281, 2 figs. 

JEANNEL, R., 1942, La genese des faunes terrestres. Paris, 337 pp. 

KOBELT, W., 1898, Studien zur Zoogeographie. I. Die Fauna der meridionalen 
Sub-Region. Wiesbaden, 368 pp. 

LA GRECA, M. & SACCHI, C. F., 1957, Problemi del popolamento animale nelle 
piccole isole mediterranee. Ann. Inst. e Mus. Zool. Univ. Napoli, 9: 1-189, 
20 figs., 7 tabs.. 

PAULUCCI, M., 1878, Materiaux pour servir a l’étude de la faune malacologique 
terrestres et fluviatile de l’Italie et de ses iles. Paris, 54 pp. 

PAULUCCI, M., 1882, Note malacologiche sulla fauna terrestre e fluviatile dell'isola 
di Sardegna. Bull. Soc. Malacol. Ital., 8: 139-381, 9 tabs. 

PAULUCCI, M., 1886, Conchiglie terrestri e d'acqua dolce del Monte Argentario e 
delle isole circostanti. Bull. Soc. Malacol. Ital., 12: 6-62, 2 tabs. 

PFEIFFER, K., 1932, Die Murellen, Helicigonen und Tacheocampylaeen des Tos- 
kanischen Archipels und des Monte Argentario. Arch. Molluskenk., 64: 173-189, 
13 tabs. 

POLLONERA, C., 1905, Molluschi terrestri e fluviatili dell’Isola d'Elba e Pianosa. 
Boll. Mus. Zool. e Anat. Compt. Torino, 20(517): 3-9, 1 tab. 

POLLONERA, C., 1909, Tacheocampylaea dell'isola di Capraia. Boll. Mus. Zool. e 
Anat. Comp. Torino, 24(608): 15-17, 1 tab. 

RAZZAUTI, C., 1917, Contributi alla conoscenza faunistica delle isole toscane. 
Atti Soc. Tosc. Sci. Nat., 31: 196-224. 

RAZZAUTI, C., 1936, Contributi alla conoscenza faunistica delle isole toscane. 4. 
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 
mediterranee. Il. Cenni biogeografici sulla malacofauna di Iviza (Pitiuse). Boll. 
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. 

SIMONELLI, V., 1889, Terreni fossili dell’isola di Pianosa nel Mar Tirreno. Boll. 
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) 


94 


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. 
Grosse. 


ABB. 


Glossodoris 


Glossodoris 


Glossodoris 


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. 


95 


96 


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. 


A 


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FIG. 4. Scheme of a longitudinal section through an acinus. 


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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ABB. 3. Okologisches Bild der Molluskenfaunen in Kalkschlammschichten der Budapester 


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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 
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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 


Y 


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). 


ES 


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, 


LITERATUR 


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Ztschr. f. Immunitätsforschung, Allergie u. klinische Immunologie, 131: 475-479. 

FRÖSCHL, K., 1968, Erfahrungen der Schneckenfarm Schlag, Königswiesen. tip, 
Nürnberg, 6: 463-464. 

HAFERLAND, W., KIM, Z., UHLENBRUCK, G., & NELSON, D. S., 1967, Zur Frage 
der Einheitlichkeit des Agglutinins Anti-Ahej]. Ztschr. f. Immunitätsforschung, 
Allergie u. klinische Immunologie, 132: 93-102. 

HEIN, G., 1952, Die Weinbergschnecke. Lebensweise, Verbrauch, Handel u. Zucht. 
Ztschr. f. hygien. Zoologie, Berlin, 40: (Heft 8/9). 

JUNGWIRTH, F. J., 1967, Die Zucht der Weinbergschnecke, Helix pomatia. Ein im 
Entstehen begriffener Erwerbszweig. Vlg. Jungwirth, Hausen/Kill. W. Germany. 

KIM, Z., UHLENBRUCK, G., PROKOP, O., & SCHLESINGER, D., 1966, Über die 
B-Substanz und das Anti-Anel von Helix pomatia. Ztschr. f. Immunitätsforschung, 
Allergie und klinische Immunologie, 130: 290-295. 

KOENIGER, K., 1965, Die Zucht der Weinbergschnecke in einem nicht typischen 
Schneckengebiet. Tip, Nürnberg, 11: 823-824 und tip, 12: 910-912. 

KOENIGER, K., 1966, Die Zucht der Weinbergschnecke in einem nicht typischen 
Schneckengebiet. tip, 1: 23-25. 

KOENIGER, K., 1967, Weinbergschnecken fühlen sich pudelwohl. tip, 10: 749-751. 

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stances mucoides qu'il sécréte, au moyen d'un extrait de sécrétions de Gas- 
téropodes. Ann. pharm. franc., 8: 734-736. 

MARQUART, R., 1909, Die Schnecken, Zoolog. Beobachter, Ludwigsburg, 50: 112-114. 

MEISENHEIMER, J., 1912, Die Weinbergschnecke. Vlg. Klinkhardt, Leipzig. 

NAWRATIL, O. J., 1963, Berichte aus dem ADKPZ in Osterreich. tip, Nurnberg, 
6: 406-408. 

NAWRATIL, O. J., 1963, Trockenresistenz von Helix pomatia. tip, 7: 437-440. 

NAWRATIL, O. J., 1963, Zucht und Ztichtung, tip, 8: 510-513. 


140 PROC. THIRD EUROP. MALAC. CONGR. 


NAWRATIL, O. J., 1963, Ziichtung einer neuen Rasse aus einer Wildform. tip, 9: 
622-624. 

NAWRATIL, O. J., 1964, Verwertung von Schnecken in aller Welt. tip, 4: 274-276. 

NAWRATIL, O. J., 1964, Neue Wegeinder Zucht von Speiseschnecken. tip, 5: 352-354. 

NAWRATIL, O. J., 1964, Wichtiges zur Ernährungsfrage der Weinbergschnecken nach 
der Winterruhe. tip, 6: 407-409. 

NAWRATIL, O. J., 1964, Futterbedarf der Weinbergschnecken in Gehegen. tip, 7: 
496-498. 

NAWRATIL, O. J., 1965, Erste Ergebnisse der Mitarbeiter in Osterreich. tip, 4: 
295-296. 

NAWRATIL, O. J., 1966, Neue Forschungsvorhaben des ADKPZ für die kommende 
Weinbergschneckensaison 1966. tip, 3: 179-181. 

NAWRATIL, O. J., 1966, Schneckenparadies in der Stidsee. tip, 9: 676-678. 

NAWRATIL, O. J., 1966, Unterstützung geplanter Forschungsvorhaben auf dem Gebiet 
der Weinbergschneckenzucht durch österreichische Förderungsgesellschaften. 
tip, 10: 745-748. 

NAWRATIL, O. J., 1966, Praktische Erfahrungen über den Einfluss des Bodens und 
des Bewuchses in Schnecken-Zuchtgehegen. tip, 11: 834-836. 

NAWRATIL, O. J., 1967, Zur Frage der Ursache von Verlusten in Weinbergschnecken- 
gehegen. tip, 8: 633-635. 

NAWRATIL, O. J., 1967, Haltungsfragen und Wachstumsleistungen in Terrarien 
gezüchteter Achatinen und Placostylen. Sitzungsberichte 4. österr. Akad. 4. 
Wiss., Mathem.-nat. wiss. Kl., Abt. I, 176: 5-20. 

NAWRATIL, O. J., 1968, Ausfälle in der Weinbergschneckenzucht durch dauernde 
Beschattung. tip, 7: 542-545. 

NAWRATIL, O. J., 1968, Zur Fütterungsfrage in den Weinbergschneckengehegen. 
tip, 8: 633-635. 

NAWRATIL, O. J., & LOEW, J., 1969, Zur Frage einer bakteriellen oder Virenin- 
fektion von Helix pomatia in Farmgehegen. Ztschr. f. Bakt., Mikrobiol. u. Hygiene, 
in Druck. 

NAWRATIL, O. J., & LOEW, J., 1969, Uber die bakteriostatische Substanz in Helix 
ротайа und deren Entstehungsbedingungen. In Vorbereitung. 

NIETZKE, G., 1963, Die Weinbergschnecke. Vlg. Eug. Ulmer, Stuttgart. 

PANTLEN, H., 1953, Ein neuer Weg der Pertussisbehandlung. Med. Klinik, 34: 
1223-1224. 

PROKOP, O., SCHLESINGER, D., & RACKWITZ, A., 1965, Uber eine thermostabile 
“antibody-like substance” (Anti-Apej) bei Helix pomatia und deren Herkunft. 
Ztschr. f. Immunitäts- u. Allergieforschung, 129: 402-412. 

PROKOP, O., RACKWITZ, A. & SCHLESINGER, D., 1965, A “New” Human Blood 
Group Receptor Ape]. Journ. forensic Med., 12: 108-110. 

PROKOP, O., 1967, Die Helixagglutinine. Allergie u. Asthma, 13: 96-98. 

PROKOP, O., SCHLESINGER, D. & GESERICK, G., 1967, Thermostabiles B-Agglutinin 
aus Konserven von Lachskaviar. Ztschr. f. Immunitätsforschung, Allergie u. klin. 
Immunologie, 132: 491-494. 

PROKOP, O., GRAFFI, A. & SCHNITZLER, ST., 1968, “Immunochemical Endgroup- 
ing” mit Helix- Agglutininen an Aszitestumorzellen. Vergleich mit den Blut- 
zellen der Tiere. Acta biol. germ., 20: K9-15. 

PROKOP, O., UHLENBRUCK, G. & KOHLER, W., 1968, Anew source of antibody-like 
substances having anti-blood group specifity. Vox Sanguinis, 14: 321-333. 

PROKOP, O., UHLENBRUCK, G. & KÖHLER, W., 1968, Protectine, eine neue Klasse 
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 


20 


°/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 

DY 


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. 


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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 


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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 


5 


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.). 
a-d at characteristic times. Collapse 4 min 
after loading and blocked lengthening in Nos. 1 REFERENCES 
and 2; successful catch in No. 1 and failure (x) 
in No. 2 at 5 1/2 min. BOZLER, E., 1930, Untersuchungen 
Both followed by once more interruption zur Physiologie der Tonusmuskeln. 
(niv. c) and return to niv. b. The N-prepara- Z. vergl. Physiol. 12: 579-602. 


tion tries to interrupt extension at niv. c, 
known from the P-preparation after 8 1/2; and 
once more at niv. d after 12 min lengthening. 


BULBRING, E., 1955, Correlation be- 
tween membrane potential, spike dis- 
charge and tension in smooth muscle. 
J. Physiol. 128: 200-221. 
DEANE, Н. W. & TWAROG, В. M., 1957, Histology of an invertebrate smooth muscle. 
Anat. Rec., 128: 538-539. 

HANSON, J. & LOWY, J., 1964, The structure of actin filaments etc., of vertebrate 
striated muscle. Proc. R. Soc. B.,160: 449-459. 

HUXLEY, H. E., 1956, Muscular contraction. Endeavour 15: 177-188. 

HUXLEY, H. E., 1964, Structural arrangements and the contraction mechanism in 
striated muscle. Proc. В. Soc., В. 160: 442-448. 

HUXLEY, H. E., 1965, The mechanism of muscular contraction. Sci. Am., 213: 18-27. 

JOHNSON, W. H., KAHN, J. $. € SZENT-GYÓRGYI, A. G., 1959, Paramyosin and con- 
traction of “catch muscles'. Science, 130: 160-161. 

JORDAN, H. J., 1905a, Untersuchungen zur Physiologie des Nervensystems bei 
Pulmonaten. Pflüg. Arch. ges. Physiol., 106: 189-228. 

JORDAN, H. J., 1905b, Untersuchungen zur Physiologie des Nervensystems bei 
Pulmonaten. Pflüg. Arch. ges. Physiol, 110: 533-597. 

JORDAN, H. J., 1930, Der Tonus glatter Muskeln als Funktion der Muskelfluiditát 
u.s.w. Proc. R. Acad. Sci., Amsterdam, 33: 788-791. 

JORDAN, H. J., 1935, Tonische Verkürzung und tonisches Festhalten der Verkürzung 
bei den Muskeln von Aplysia limacina unter Einfluss wechselnder Temperaturen. 
Proc. R. Acad. Sci., Amsterdam, 38: 358-364. 


162 PROC. THIRD EUROP. MALAC. CONGR. 


JORDAN, H. J. & KIPP. P. J., 1939, Die Leistungen und feine Struktur der glatten 
Hohlmuskeln bei Metridium senileL. Proc. R.Acad. Sci.,Amsterdam, 42: 849-858. 

LEENDERS, H. J., 1966, Kontraktion und Spannungsrückstand an glycerinextrahierten 
Muskelfasern (ABRM) von Mytilus edulis. Naturwiss., 53: 617. 

LEENDERS, H. J., 1967a, Der Einfluss der Sperrung auf die Kontraktion. Unter- 
suchungen am ABRM von Mytilus edulis Г. Pflüg. Arch., 295: 127-135. 

LEENDERS, H. J., 1967b, Ca-coupling in the anterior byssus retractor muscle of 
Mytilus edulis L. J. Physiol., 192: 681-693. 

LOWY, J. & MILLMAN, B. M., 1959a, Contraction and relaxation in smooth muscles 
of lamellibranch molluscs. Nature, Lond., 183: 1730-1731. 

LOWY, J. & MILLMAN, B. M., 1959b, Tonic and phasic responses in the anterior 
byssus retractor muscle (ABRM) of Mytilus. J. Physiol., 149: 68P-69P. 

NIEUWENHOVEN, S. J., L. M. v. & POSTMA, N., 1969, Le comportement mécanique 
de la musculatur du pied de l’Aplysie ponctuée (Aplysia punctata Cuv.) et sa base 
nerveuse. Neth. J. Zool. 19: 140-143. 

PORTZEHL, H., 1952, Der Arbeitszyklus geordneter Aktomyosinsysteme (Muskel und 
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POSTMA, N., 1933, Recherches sur l’allongement dupieddel’escargot (Helix pomatia 
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POSTMA, N., 1942, Active changes in the (viscosoid) tonus of smooth muscles ex- 
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POSTMA, N., 1962, Some features of gastropod musculature and the control mecha- 
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POSTMA, N., 1963, The contribution to smooth muscle physiology in general by the 
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POSTMA, N., 1967, Zwei Beispiele von “innerer Unterstützung” derVerkürzungs- 
aktivität des Fusses der Weinbergschnecke. Pflüg. Arch., 294: 49. 

POSTMA, N. & MERTENS, J., 1966, Ueber Reizschwellen für Tonuslösung beim 

.„ Mytilus-ABRM und Helix-Fuss. Pflüg. Arch., 289: 5. В 40. 
RUEGG, J. C., 1960, Tropomyosin and tonus in lamellibranch adductor muscles. 
‚ Biochem. bio-phys. Acta, 35: 278-279. 

RUEGG, J. C., 1963, Actomyosin inactivation by thioura and the nature of viscous 
tone in а molluscan smooth muscle. Proc. В. Soc., В. 158: 177-195. 

RÜEGG, J. C. & TREGAR, R. T., 1966, Mechanical factors affecting the ATPase 
activity of glycerol-extracted insect fibrillar flight muscle. J. Physiol., 165: 
497-512. 

SCHLOTE, F. W., 1955, Die Erregungsleitung im Gastropodennerven und ihr his- 
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SZENT-GYORGYI, A. G., 1953, Meromyosins, the sub-units of myosin. Arch. Bioch. 
& Biophys., 42: 305-320. 

TWAROG, B. M., 1960, Innervation and activity of a molluscan smooth muscle. 
J. Physiol., 152: 220-235. 

TWAROG, В. M., 1967, The regulation of catchin molluscan muscle. J. gen. Physiol., 
50: 157-169. 


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. 


REFERENCES 


ATKINS, D., 1938, On the ciliary mechanisms and inter-relationships of lamelli- 
branchs. VII, Latero-frontal cilia of the gill filaments and their phylogenetic 
value. Quart. J. micr. Sci., 80: 346-436. 

COX, L. R., 1960, Thoughts on the classification of the Bivalvia. Proc. malac. 
Soc. Lond., 34: 60-88. 

DINAMANI, P., 1967, Variation in the stomach structure ofthe Bivalvia. Malacologia, 
5: 225-268. 

GHISELIN, М. T., DEGENS, Е. T., SPENCER, D. W. & PARKER, В. H., 1967, A 
phylogenetic survey of molluscan shell matrix proteins. Breviora, 262: 1-35. 

GRAHAM, A., 1934, The cruciform muscle of lamellibranchs. Proc. roy. Soc. Edinb., 
54: 17-30. 


PURCHON and BROWN 171 


GRAHAM, A., 1934a, The structure and relationships of lamellibranchs possessing 
a cruciform muscle. Proc. roy. Soc. Edinb., 54: 158-187. 

OCKELMANN, K. W., 1964, Turtonia minuta (Fabricius), a neotenous veneracean 
bivalve. Ophelia, 1: 121-146. 

OLDFIELD, E., 1955, Observations on the anatomy and mode of life of Lasaea rubra 
(Montagu) and Turtonia minuta (Fabricius). Proc. malac. Soc. Lond., 31: 226-249. 

OWEN, G., 1959, The ligament and digestive system in the taxodont bivalves. Proc. 
malac. Soc. Lond., 33: 215-223. 

PELSENEER, P., 1891, Contribution a l’étude des lamellibranches. Arch. de Biol., 
11: 147-312. 

PELSENEER, P., 1906, A Treatise on Zoology, ed. E.R. Lankester, У, The Mollusca. 
A. & C. Black, London. 

PELSENEER, P., 1911, Les lamellibranches de l’expedition du Siboga, Partie anato- 
mique. Siboga Expéditie. Monogr. No. 53а. 

PURCHON, R. D., 1941, On the biology and relationships of the lamellibranch 
Xylophaga dorsalis (Turton). Journ. mar. biol. Assn. U.K., 25: 1-39. 

PURCHON, R.D.,1959, Phylogenetic classification of the Lamellibranchia, with special 
reference to the Protobranchia. Proc. malac. Soc. Lond., 33: 224-230. 

PURCHON, R. D., 1960, The stomach in the Eulamellibranchia; stomach types IV and 
У. Proc. Zool. Soc. Lond., 135: 431-489. 

PURCHON, В. D., 1960a, Phylogeny in the Lamellibranchia. Proc. Cent. € Bicent. 
Congr. Biol. Singapore, 1958, 69-82. 

REID, R. G. B., 1965, The structure and function of the stomach in bivalve molluscs. 
Journ. Zool., 147: 156-184. 

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. 


a 


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). 


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#9 


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 


à 


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. 


nee 


N : 
eer 
a no Gage 9295059919949. 


= E av? ÿ 
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Vddr 


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Mf 


90009 9 PIS Pag: SUT Pr en 


| y um 


d 
M Cd 


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 


Sp 


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 


WN 
< © 
= <x 
Zn pm ME 
uJ < O O = © O 
SOI = <I a 5 
rae Fad eV ee So O a 
о = о = œ > E < 
O ш о Mm = = oO E 
=) = < == un < < а. 
< O =) œ < = о WU 
О Ww ae E (6) co (09) x 
- EV 
< a Ss 
ui a a 
о x oa 
< вое 
= о 
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=E O Su > 
2 ozaaz 
o = 
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4 ы | © 
= = = 
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a are 


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 
I 
OH 


И) 


D) 4 
EQ 
==; 


Zp, 
7 | 
YH AN 
РЕ Е 
| 


o 
A А / 
\ 


/ Y 


we 


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). 


, 


D 


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: 


a) 


b) 


c) 


d) 


e) 


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 


g) 


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 


.M 


ANTHOZOA SCYPHOZOA HYDROZOA 


CNIDARIA 


© NEMATHEL- 


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 


Tr ad 


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Sekundarer Hartboden aus 
Kalkalgen, Bryozoen ‚Schell u à 


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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 & 


© © — ve pressure QE) @ O (5) 


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. 


(c) Sepia officinalis (L.) 


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. 


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CHAPMAN, G., 1958, The hydrostatic skeleton in the invertebrates. Biol. Rev., 
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248 PROC. THIRD EUROP. MALAC. CONGR. 


CHAPMAN, G. & NEWELL, G. E., 1956, The role of the body fluid in relation to 
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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. 


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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. 


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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 


A. C. van BRUGGEN 


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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. 


(259) 


260 PROC. THIRD EUROP. MALAC. CONGR. 


(AD 

2 5 < 4 ÉS <A 

gs LA ES EB SB XX =>» «==> 28 ES ES 
a 

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 


L 


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. 


о 


1 RIN-communication №. 3 


(261) 


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. 


(263) 


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 


(265) 


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. 


(268) 


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. 


(282) 


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: 


(284) 


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 


(286) 


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. 

(288) 


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. 


(289) 


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. 


(290) 


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. 


(291) 


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. 


j 
| 2 
3 
| 4 
6 
20° 20° 
7. 
8g 
10 
$ 
a “gu t 
8 
10° 112 ii | te 10° 
17 o, 
©. 
À pS 19 
0°C 6.05 | | oc 
"Y — temper. 
0 10 20 30 40mm 50 


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 


(293) 


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- 


(295) 


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. 


(297) 


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 


A 


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, 

26 

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 


98 


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 


MALACOLOGIA 


International Journal of Malacology 
Revista Internacional de Malacologia 
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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. 
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KREJCI GRAF, K. & WENZ, W., 1926, Jung- 
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MARINESCU, FL., 1964, Propuneri си privire 
la orizontarea Pontianului din partea occi- 
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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 


Us 


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 


progeny 
F,-f 
> I 
oan Xx 
60% Ту | 40% Tn 
(F;-k) 
| 
и у 
SOUS У | AIS INE ЕД Чи 
(Е.-К) 
GG | 
Ze И 
50.5% Ту о ТУ 43% Tin 
(ave. F,-d, F,-e) 
za 
LA | 
50% Ту SIG) ТУ Ао Ти 
(ave. Ез-а, F,-b) 
Ge 
Z и 
439: In 


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 


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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 


33 


3 


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 


enot e 
u Tv/total Ту Y Pigment Tv/total Tv % 
ratio 
Cross 1 | 
BA 16/30 3305 3B:3A 5/6 835% 
AA | 16/37 43% 16B:18A 18/34 53% 
Totals 32/67 48% 23/40 58% 
Cross 2 | 
CG | * 41% died 
AA | 10/20 50% 


*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 


ea 


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 


3 


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) 


BU 


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 

4 


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 


SS 


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 


En 


ca 


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. 


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CROFTS, D. R., 1955, Muscle morphogenesis in 
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De BEER, С. R., 1958, Embryos and ancestors. 
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FIORONI, P., 1967, Quelques aspects de l’em- 
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388 CHARLES 


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D’ASARO 


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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 


# 7 2 = Le 
en Seb tern: 1 tuted “bap? qe ART at | t A 
= Ene ЕЩЕ | e o 4 1. Pers A mA BT IE a AR № ol 
ЕН: а 7 A ow | E ИА у >, 
IA E a ь <a м cone clips 
PER. 40110 - | ea FS AE 
Ce DEE ET rh 2: Le в: 4 Ñ 
у 0 Y = р i 
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u Л wo 


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 


05 


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 


6 


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 

> 90%rh 
5 
© 
> 
E 
® 
S 50%rh 
© 
a 


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. 

7. Temperature 2э-©. 

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 

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 


60 
= 
a 
E 
o 40 
> 
= 
о 
ZO. 
© 
a 

O 

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. 


7 


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... 


40 


20 


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 


80 


60 


Percent Mortality 


J 

= 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) 


7 


SCULPTURED LARVAE 


GG 


Za 

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) 


8 


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 
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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. 
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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- 
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137-166. 

STRUHSAKER, J. W., 1968, Selection mechan- 
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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 


mg 


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 


B 


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. 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 


C 


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 

9 


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 

© Caecum 


EG ©©. Columnar cells; types № and 25 of 


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 


M ' ИА — IA к 
SE Kae EU REZ 
Fer | ae, NCE 
RL RS ETS OS 857 
27 
ZN I CN 


ERA 
ANA = 


4 =D ÈS 
ELE NATA E SOS 
4. DUR 
| Y) Qt 


} д: Y e 
ies 


Ñ 


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. 


ce 


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 


=a 


у 


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 


11 


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 


3! 


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.) 


| | 
| Salivary Gland of | Маш | Stomach 

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 


© 
о 
o 


+ 
о 
о 


200 


micromoles 2-naphthol liberated /дгат,/ hour 


о 
a 
о 


6.0 70 8.0 9.0 10.0 


pH 


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 


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 


90 


8.0 


РН 70 


6.0 


50 


40 


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 

12 


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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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 


4 


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. 


13 


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 


BOYER, S. H., 1961, Alkaline phosphatase in 
human sera and placentae. Science, 134: 
1002-1004. 


BURSTONE, M. S., 1958, Histochemical com- 
parison of naphthol-AS-phosphates for the 
demonstration of phosphatases. J. Natl. 
Cancer Inst., 20: 601-616. 


BUTTERWORTE Р. Is, MOSS) DW. РМ 
KANEN, E. & PRINGLE, A., 1965, Some 
characteristics of alkaline phosphatase in 
human urine. Clin. Chim. Acta, 1]: 220-226. 


CHIANDUSSI, L., GREEN, S. F. & SHER- 
LOCK, S., 1962, Serum alkaline phosphatase 
fractions in hepato-biliary and bone diseases. 
Clin. Sci., 22: 425-434. 


HODSON, A. W., LATNER, А. L. & RAINE, 
L., 1962, Isoenzymes of alkaline phosphatase. 
Clin. Chim. Acta, 7: 255-261. 


KEIDING, N. R., 1959, Differentiation into 
three factions of the serum alkaline phospha- 
tase and the behaviour of the fractions in 
diseases of bone and liver. Scand. J. clin. Lab. 
Invest., 11: 106-112. 


———-— 1964, The alkaline phosphatase frac- 
tions of human lymph. Clin. Sci., 26: 291-297. 


KLEIN, В.. READ, P. A. € BABSON, A. L., 
1960, Rapid method for the quantitative deter- 
mination of serum alkaline phosphatase. Clin. 
Chem., 6: 269-275. 


MANIGAULT, P., 1939, Rechereches sur le 
calcaire chez les mollusques. Phosphatase et 
precipitation calcique. Histochimie du cal- 
cium. Ann. Inst. oceanogr., 18: 331-426. 


MORRIL, J. B. & NORRIS, E., 1965, Electro- 
phoretic analysis of the hydrolytic enzymes in 
the //yanassa embryo. Acta Embryol. Morphol. 
exp., 8: 232-238. 


NEUMAN, W. F., DISTEFANO, V. & MUL- 
RYAN, В. J., 1951, The surface chemistry of 
bone. IIL. Observations on the role of phos- 
phatase. J. biol. Chem., 193: 227-235. 


NORRIS, E. & MORRIL, J. B., 1964, An elec- 
trophoretic analysis of hydrolytic enzymes in 
adult organs and developing embryo of Limnaea 
palustris. Acta Embryol. Morphol. exp., 7: 
29-41. 


SALEUDDIN, А. 5. M., 1967, The histochemis- 
try of the mantle during the early stage of the 
repair of the shell. Proc. malac. Soc. Lond., 
37: 371-380. 


SIMKISS, K., 1964, Phosphates as crystal poisons 
of calcification. Biol. Rev., 39: 487-505. 


TASWELL, H. F. & JEFFERS, M. T., 1963, 
Isoenzymes of serum alkaline phosphatase in 
hepatobiliary and skeletal diseases. Amer. J. 
Clin. Path., 40: 349-356. 

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. 

ID 


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 


DIRECTIONS TO AUTHORS 


MALACOLOGIA will publish the results of original work, of either descriptive or experimental nature, 
devoted primarily or exclusively to the study of mollusks. The articles must not be published elsewhere. 
Contributions may include longer monographs or comprehensive reviews, as well as short research papers, 
but brief notes are not acceptable MALACOLOGIA aims to provide a common medium for such 
different aspects of malacology as anatomy, ecology, medical malacology, paleontology, physiology and 
taxonomy. The journal is especially concerned with maintaining scholarly standards. АП manuscripts 
will be reviewed by atleast two editors. 


Manuscripts may be in English, French, German, Russian or Spanish, and should follow MALA- 
COLOGIA style. They must contain a concise but adequate abstract for translation into the other 
languages. Manuscripts must be type-written, double spaced, with top and left-hand margins atleast 
3 cm wide, and are to be submitted in duplicate (carbon copy on thin paper). 


Contributors in the English language are advised to follow the recommendations of the Style Manual 
for Biological Journals obtainable from the American Institute of Biological Sciences, 2000 P Street N.W., 
Washington, D.C. 20036, U.S.A. In particular, simplified practices, such as the following are favored: 
numbers should not be written out except at the beginning of a sentence; percentages following a number 
are expressed as %; abbreviations of measures (after a number): mm, ml, kg, etc. have no period nor 
an s in the plural. 


Illustrations must be carefully executed and so planned thai they may be printed as figures of a size 
appropriate to either one column or the full width of a page of the journal. The maximum size of a 
printed figure is 13:5 20cm. Large illustrations must be accompanied by a smaller photograph for the 
editors. Drawings and lettering must be in black India ink or carbon black printing on white, 
blue tracing, or blue-lined paper. Charts should be drawn large enough to stand a reduction of one half 
to one third. This should be taken into consideration especially in relation to the lettering. Letters and 
numbers must not be less than 1 mm in height. preferably larger, after reduction. A number of drawings 
or photographs may often be conveniently grouped together to fit a page. 


Bibliography. See current number of MALACOLOGIA for desired form of citing. In particular, 
it should be noted that the journal uses the ampersand (&) for ““ and ”; “et al.” may be used in the text, 
but not in the list of references at the end: in addition to the volume number, complete page numbers of 
articles and books must be cited: for books, the publisher and city also must be cited. 


Reprints. Authors will receive 50 reprints gratis; additional copies may be obtained at cost price if 
ordered at the time off-set proof is returned. Later orders cannot be considered. 


Correspondence. АП manuscripts and figures, as well as inquiries, should be sent directly to the 
Managing Editor, C. J. Bayne, Museum of Zoology, The University of Michigan, Ann Arbor, Michigan 
48104, U.S.A. 


14 


ANWEISUNGEN 


MALACOLOGIA nimmt zur erstmaligen Veröffentlichung die Ergebnisse eigener Untersuchungen an, 
die sich—beschreibend oder experimentell—hauptsächlich oder ausschliesslich mit der Erforschung der 
Weichtiere befassen. Es dürfen umfassende Ubersicnten, längere Monographien oder auch kärzere 
Studien sein; Notizen oder Kurzberichte werden jedoch nicht angenommen. MALACOLOGIA ist eine 
streng Wissenschaftliche Zeitschrift, die den verschiedenen Disziplinen, wie der Anatomie, Taxonomie, 
Oekologie, Physiologie, usw., soweit sie die Weichtierkunde betreffen, sowie auch der Paläontologie und 
der medizinischen Malakologie ein gemeinsames Forum bieten soll. Alle Manuskripte werden von 
zumindest 2 Lektoren auf Eignung geprüft. 


Beiträge können in englischer, deutscher, französischer, spanischer oder russischer Sprache abgefasst 
sein, sollen sich aber an den von MALACOLOGIA geforderten Stil halten Ein kurzge. fasster, jedoch 
aufschlussreicher Auszug wird fur die Übersetzung in andere Sprachen verlangt. Manuskripte sollen 
maschinegeschrieben, mit Leerzeiletúnd einem 3 cm Rand links und oben, in doppelter Ausführung 
(Durchschlag auf dúnnem Papier) unterbreitet werden. Die folgenden vereinfachten Schreibweisen sind 
erwünscht: Zahlen werden nur am Anfang des Satzes ausgeschrieben; nach Zahlen werden Prozente mit 
dem %-Zeichen wiedergegeben, die Abkürzungen der Maszeinheiten, wie z.B. mm, ml, mg, cm, usw., 
bleiben ohne Punkt, wie hier aufgeführt. 


Abbildungen müssen sorgfältigst ausgefährt und im Format so genalten sein, dass sie, nach 
entsprechender Verkleinerung, entweder auf einer Spalte oder auf der vollen Breite einer Seite Platz finden. 
Das Höchstausmasz einer veröffentlichten Abbildung beträgt 12.5 20 cm. Grossen Illustrationen müssen 
kleinere Photographien davon beigelegt werden. Zeichnungen und Bischriftung sind mit Tusche bsw. 
schwarzem Karbondruck auf weissem oder blaukariertem Papier oder auf blauem Pausleinen auszuführen. 
Tabellen, Karten und sonstige graphische Darstellungen müssen gross genung sein um bei einer 
Verkleinerung auf halbe bis drittel Grösse noch deutlich lesbar zu bleiben, d.h. Zahlen oder Buchstaben 
sollen dann noch zumindest | mm hoch sein. Es wird empfohlen, Zeichnunger oder Lichtbilder tunlichst 
so zu gruppieren, dass sie ohne Platzverschwendung auf einer Seite untergebracht werden können. 


Bibliographie. Die gewünschte Form des Zitierens ist aus Argendeinem der jüngeren Hefte ersichtlich. 
Zu merken ist in dieser Hinsicht insbesondere der Gebrauch des &-Zeichens bei Angabe der Autoren. 
Der Ausdruck “et al.” (bzw. “und Mitarbeiter ”) darf zwar in Text gebraucht werden, nicht aber im 
Literaturverzeichnis am Ende der Arbeit, wo alle Autoren namentlich angeführt werden müssen. Ausser 
Angabe des Jahrganges (Nummer des Bandes) werden auch die Seitenzahlen, bei Zeitschriften wie bei 
Büchern, verlangt; bei letzteren auch Herausgeber (Verlag) und Verlagsort. 


Sonderdrucke. Die Verfasser erhalten 50 Separata unentgeltlich. Weitere Exemplare sind zum 
Selbstkostenpreis erhältlich, müssen aber spätestens bei Erhalt der Korrekturfahne bestellet werden; 
spätere Bestellungen können nicht mehr perücksichtigt werden. 


Korrespondenz. Beiträge, Bestellungen, Zahlungen oder Anfragen sind zu richten an: С. J. Bayne 
Managing Editor, MALACOLOGIA, Museum of Zoology, The University of Michigan, Michigan 
48104, U.S.A. 


DIRECTIVES AUX AUTEURS 


MALACOLOGIA accepte de publier des travaux originaux, soit descriptifs soit expérimentaux, 
consacrés principalement ou exclusivement à l’étude des Mollusques. Les contributions peuvent être 
de longues monographies ou des Mises-au-point synthetiques ainsi que de courts articles de recherches, 
mais les notes bréves ne sont pas acceptées. MALACOLOGIA a pour but d’etre l’organe d’expression 
commun pour divers sujets malacologiques tels que l’anatomie, l’ecologie, la malaco'ogie medical», la 
paléontologie, la physiologie et la taxonomie. Le journal s'attache tout particuliérement à maintenir 
un certain niveau d’érudition. Tous les manuscrits sont revus par au moins deux éditeurs. 


Les manuscrits peuvent étre en anglais, francais, allemand, russe ou espagnol, et devront suivre le style 
de MALACOLOGIA. Ils doivent contenir un resume bref mais suffisant, pour la traduction dans les 
autres langues. Les manuscrits doivent étre tapés а la machine, a double interligne. avec en haut et a 
gauche, une marge d’au moins 3 cm et étre fournis en double exemplaire (copie au carbone sur pelure). 


Les auteurs de langue anglaise sont priés de suivre les recommandations du Style Manual for Biological 
Journals que Von peut acquérir a l’American Institute of Biological Sciences, 2000 P Street, N.W., 
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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