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VOL. 19 1979-1980

MALACOLOGIA

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

Internationale Malakologische Zeitschrift

Publication dates

Vol. 17, No. 2—27 July 1978
Vol. 18, No. 1-2—18 May 1979
Vol. 19, No. 1—19 September 1979

IN MEMORIAM

PAUL S. GALTSOFF
(1887-1979)

ERRATUM

Vol. 18, р. 320, Table 1, line 2: for “Les valeurs en concernent . . . read “Les valeurs en
caractères gras [boldface] concernent. . . .”

MALACOLOGIA, VOL. 19

CONTENTS

Mr DILLON: Ur:

Multivariate analyses of desert snail distribution in an Arizona canyon ...... 201
. В. FRANZ and А. $. MERRILL

Molluscan distribution patterns on the continental shelf of the Middle

Allantie’Bightt(nortnwestyAllantie)en Sd ae chins oni ee ee 209
. В. FRANZ and А. $. MERRILL

Тре origins and determinants of distribution of molluscan faunal groups

on the shallow continental shelf of the northwest Atlantic .................. 227
. C. JONES

Anatomy of Chione cancellata and some other chionines (Bivalvia:

VENTES) у 157
. 1. KAFANOV

Systematics of the subfamily Clinocardiinae Kafanov, 1975 (Bivalvia,

Eardiidae) RSR PR Ne O O ER: 297
. KERTH

Phylogenetische Aspekte der Radulamorphogenese von Gastropoden ...... 103
. S. LIPTON and J. MURRAY

Courtship of: land 'Snailsroftne dents Paula Ce ar a ea 129
. MARTOJA et С. THIRIOT-QUIEVREUX

Appareil génital de Carinaria lamarcki (Gastropoda Heteropoda); struc-

UTC ANIMÉS rc er. ER nn, O р 63
. À. MCCONATHY, R. T. HANLON and R. F. HIXON

Chromatophore arrangements of hatchling loliginid squids (Cephalo-

раму орала. р AI CCE ЕЕ 279
. В. PALMER

Locomotion rates and shell form in the Gastropoda: a re-evaluation ........ 289
. B. PICKEN

Non-pelagic reproduction of some Antarctic prosobranch gastropods

from Signy Island, South Orkney Islands ........................ IN 109

. PINEL-ALLOUL et E. MAGNIN

Cycle de développement, croissance et fécondité de cinq populations de
Lymnaea catascopium catascopium (Gastropoda, Lymnaeidae) au Lac
Sainl-kouis AQUÉDECN Canada er a O TRE e 87

MALACOLOGIA
CONTENTS (contd.)

J. F. QUINN, Jr.

Biological results of the University of Miami Deep-sea Expeditions. 130.

The systematics and zoogeography of the gastropod family Trochidae

collected in the Straits of Florida and its approaches ..................

P. H. RUDOLPH

An analysis of copulation in Bulinus (Physopsis) globosus (Gastropoda:

Planorbidae) oct: intra Mees eco: > etek ae AAA

L. v. SALVINI-PLAWEN

A reconsideration of systematics in the Mollusca (phylogeny and higher

classification) овес le ne ie MRC ERG SRE IIA

M. J. S. TEVESZ and J. G. CARTER

Form and function in Trisidos (Bivalvia) and a comparison with other

burrowing загсе: ea. 252 LEE A: AVES RD ee

С. J. VERMEIJ

Drilling predation of bivalves in Guam: some paleoecological implications ...

329

MUS. COMP. ZOOL,
LIBRARY

SEP 2 8 1979

HARVARD
WNIVERSITY.

1979

MALACOLOGIA

AO

al International de Malacologie
ждународный Журнал Малакологии

Internationale Malakologische Zeitschrift —

MALACOLOGIA
Editors-in-Chief:
GEORGE M. DAVIS ROBERT ROBERTSON

Editorial and Subscription Offices:

Department of Malacology
The Academy of Natural Sciences of Philadelphia
Nineteenth Street and the Parkway
Philadelphia, Pennsylvania 19103, U.S.A.

Associate Editors: Editorial Assistants:
JOHN B. BURCH JUDITH DIAMONDSTONE
University of Michigan, Ann Arbor LYNN HARTLEY

ANNE GISMANN
Maadi, A. R. Egypt

MALACOLOGIA is published by the INSTITUTE OF MALACOLOGY (2415 South Circle Drive,
Ann Arbor, Michigan 48103, U.S.A.), tne Sponsor Members of which (also serving as editors)
are:

J. FRANCES ALLEN, Emeritus ROBERT ROBERTSON
Environmental Protection Agency
Washington, D.C. CLYDE F. E. ROPER, President

Smithsonian Institution
CHRISTOPHER J. BAYNE, President-Elect Washington, D.C.

Oregon State University, Corvallis
W. D. RUSSELL-HUNTER

ELMER G. BERRY, Emeritus Syracuse University, New York
Germantown, Maryland
NORMAN F. SOHL

KENNETH J. BOSS United States Geological Survey
Museum of Comparative Zodlogy Washington, D.C.

Cambridge, Massachusetts
RUTH D. TURNER, Alternate

JOHN B. BURCH Museum of Comparative Zodlogy
Cambridge, Massachusetts

MELBOURNE R. CARRIKER

University of Delaware, Lewes SHI-KUEI WU, Vice-President

University of Colorado Museum, Boulder
GEORGE M. DAVIS, Executive

Secretary-Treasurer |

Institute meetings are held the first Friday in December each year at a convenient place. One
subscriber may attend and vote by petitioning in advance. For information, address the Presi-
dent.

Copyright, © Institute of Malacology, 1979

1979

EDITORIAL BOARD

J. A. ALLEN

Marine Biological Station,
Millport, United Kingdom
E. E. BINDER

Muséum d'Histoire Naturelle
Genéve, Switzerland

A. H. CLARKE, Jr.
National Museum of Natural History
Washington, D.C., U.S.A.

E. S. DEMIAN
Ain Shams University
Cairo, A. R. Egypt

C. J. DUNCAN
University of Liverpool
United Kingdom

Z. A. FILATOVA
Institute of Oceanology
Moscow, U.S.S.R.

E. FISCHER-PIETTE
Muséum National d’Histoire Naturelle
Paris, France

VSERETTER
University of Reading
United Kingdom

E. GITTENBERGER
Rijksmuseum van Natuurlijke Historie
Leiden, Netherlands

A. N. GOLIKOV
Zoological Institute
Leningrad, U.S.S.R.

A. V. GROSSU
Universitatea Bucuresti
Romania

T. HABE

National Science Museum
Tokyo, Japan

A. D. HARRISON
University of Waterloo
Ontario, Canada

K. HATAI

Tohoku University
Sendai, Japan

B. HUBENDICK
Naturhistoriska Museet
Gôteborg, Sweden

A. M. KEEN
Stanford University
California, U.S.A.

R. N. KILBURN
Natal Museum
Pietermaritzburg, South Africa

M. A. KLAPPENBACH
Museo Nacional de Historia Natural
Montevideo, Uruguay

J. KNUDSEN
Zoologisk Institut & Museum
Kóbenhavn, Denmark

A. J. KOHN
University of Washington
Seattle, U.S.A.

Y. KONDO
Bernice P. Bishop Museum
Honolulu, Hawaii, U.S.A.

C. M. LALLI
McGill University
Montreal, Canada

J. LEVER
Amsterdam, Netherlands

A. LUCAS
Faculté des Sciences
Brest, France

N. MACAROVICI
Universitatea “Al. |. Cuza”
lasi, Romania

C. MEIER-BROOK

Tropenmedizinisches Institut
Tubingen, Germany (Federal Republic)

H. K. MIENIS
Hebrew University of Jerusalem
Israel

J. E. MORTON
The University
Auckland, New Zealand

R. NATARAJAN
Marine Biological Station
Porto Novo, India

J. OKLAND
University of Oslo
Norway

T. OKUTANI

National Science Museum
Tokyo, Japan

W. L. PARAENSE
Universidade de Brasilia
Brazil

J. J. PARODIZ

Carnegie Museum
Pittsburgh, U.S.A.

C. M. PATTERSON
University of Michigan
Ann Arbor, U.S.A.

W. F. PONDER

Australian Museum
Sydney

A. W. B. POWELL
Auckland Institute & Museum
New Zealand

R. D. PURCHON

Chelsea College of Science & Technology

London, United Kingdom

O. RAVERA
Euratom
Ispra, Italy

N. W. RUNHAM
University College of North Wales
Bangor, United Kingdom

S. G. SEGERSTRALE

Institute of Marine Research
Helsinki, Finland

G. A. SOLEM
Field Museum of Natural History
Chicago, U.S.A.

F. STARMUHLNER
Zoologisches Institut der Universitat
Wien, Austria

Y. |. STAROBOGATOV
Zoological Institute
Leningrad, U.S.S.R.

W. STREIFF
Université de Caen
France

J. STUARDO
Universidad de Chile,
Valparaiso

T. E. THOMPSON
University of Bristol
United Kingdom

г. ТОРРОЕЕТТО
Societa Malacologica Italiana
Milano

W. $. $. VAN BENTHEM JUTTING
Domburg, Netherlands

J. A. VAN EEDEN
Potchefstroom University
South Africa

J.-J. VAN MOL
Université Libre de Bruxelles
Belgium

N.H. VERDONK
Rijksuniversiteit
Utrecht, Netherlands

B. R. WILSON
National Museum of Victoria
Melbourne, Australia

C. M. YONGE
Edinburgh, United Kingdom

H. ZEISSLER
Leipzig, Germany (Democratic Republic)

A. ZILCH

Natur-Museum und Forschungs-Institut
Senckenberg

Frankfurt-am-Main, Germany (Federal
Republic)

MALACOLOGIA, 1979, 19(1): 1-62

BIOLOGICAL RESULTS OF THE UNIVERSITY OF MIAMI DEEP-SEA
EXPEDITIONS. 130. THE SYSTEMATICS AND ZOOGEOGRAPHY OF
THE GASTROPOD FAMILY TROCHIDAE COLLECTED IN
THE STRAITS OF FLORIDA AND ITS APPROACHES

James F. Quinn, Jr.

Rosenstiel School of Marine and Atmospheric Sciences, University of Miami,
4600 Rickenbacker Causeway, Miami, FL 33149, U.S.A.

ABSTRACT

Fifty-four species of molluscs in the family Trochidae are reported from the Straits of Florida in
depths of 180 m or more. The following new taxa are described: Echinogurges, n. gen. (type-
species Trochus (Margarita) clavatus Watson); Mirachelus clinocnemus, n. sp.; Solariella
(Solariella) multirestis, n. sp.; Microgaza rotella inornata, n. subsp. Microgaza vetula Woodring
is reported from the Recent fauna for the first time. The radula of Microgaza rotella rotella Dall is
described and illustrated for the first time and indicates that Microgaza is in the subfamily
Solariellinae. Each species, except those in the genera Gaza, Calliostoma and Lischkeia, is fully
described and illustrated with photographs, and synonymies and distributions are given. A
zoogeographic analysis indicates that the trochid fauna is a tropical deep-sea assemblage.

INTRODUCTION

The molluscan fauna of the Straits of Flor-
ida has been extensively, if sporadically,
sampled, beginning with the BLAKE expedi-
tions (1877-78, 1878-79, 1880) and continu-
ing to 1972, when the R/V GERDA was re-
tired from service by the University of Miami.
The identification of species from this area
has been based primarily on the work of Willi-
am Healey Dall (1881, 1889, 1927a,b). The
majority of his work was excellent, but he
often worked with scanty collections and in-
adequate literature, and mistakes and dis-
crepancies often appeared. Despite this, sub-
sequent authors have generally accepted
Dall's opinions uncritically, especially in the
archaeogastropod family Trochidae. Since
Dall, several descriptive works and a few
faunal lists have included species found in the
Straits, but except for a study of Gaza (Clench
& Abbott, 1943) and a monograph of the
genus Calliostoma (Clench & Turner, 1960),
no critical work has been attempted involving
trochids found in the Straits. Since the
GERDA collections were rather rich in
trochids, this study was selected to fill a con-
siderable gap in the systematic literature of
the Trochidae.

This study treats those species of Trochi-
dae which have been taken in depths greater
than 180 m in the Straits of Florida and deals
with the systematics and zoogeography of

(1)

this rather important group. The depth limita-
tion eliminates 11 shallow-water species from
consideration in the systematic account, but
for the sake of completeness, 10 of these are
included in the zoogeographic considerations.

LITERATURE REVIEW OF STRAITS
TROCHIDAE

In the first hundred years after Linnaeus's
10th edition of Systema Naturae was pub-
lished, 8 species of trochids assignable to the
Straits fauna were described. Linnaeus
(1758), Born (1778), Lamarck (1822) and
Arthur Adams (1854) each described 1 spe-
cies, and Gmelin (1791) and C. B. Adams
(1845, 1850) contributed 2 species apiece. All
8 are shallow water species, and only 2
(Calliostoma jujubinum Gmelin and C. pul-
chrum C. B. Adams) can be included in this
study.

The first deep water trochid to be attributed
to the Straits area per se was Solariella
amabilis (Jeffreys, 1865), a name Dall used
for Solariella pourtalesi Clench & Aguayo,
1938. S. amabilis is now known to be strictly
an Eastern Atlantic form. Watson (1879,
1886), in working up the CHALLENGER
gastropods, reported 14 new Western Atlantic
species, of which 7 are found in the Straits (in
1886 he added a fifteenth, Margarites euspira
Dall, 1881). Verrill (1880) reported on the mol-
luscs collected by the FISH HAWK and in-

2 QUINN

cluded 3 new Western Atlantic trochid spe-
cies, of which 1, Solariella lamellosa (Verrill &
Smith, 1880) is also found in the Straits.

In working up the molluscs of the BLAKE
and ALBATROSS expeditions, William
Healey Dall was primarily responsible for lay-
ing the groundwork on which most of the
Western Atlantic molluscan research is
based. In his preliminary report on the BLAKE
collections (1881) Dall recognized 24 species
of Trochidae, 19 of which were new and 14
which are now known from the Straits. His
1889 paper, the comprehensive report on the
Caribbean molluscs from the BLAKE expedi-
tions, added 13 new species, and 34 of the 45
trochids discussed are found in the Straits. A
preliminary report on the ALBATROSS expe-
dition of 1887-1888 listed 10 species, 5 now
recorded from the Straits. Finally, 2 papers on
ALBATROSS material from off southern
Georgia (Dall, 1927a, 1927b) produced 29
species of which 23 were new and 10 occur in
the Straits.

A series of papers by Clench & Aguayo
(1938, 1939, 1940, 1941, 1946) introduced 11
new species of trochids, mostly in the genus
Calliostoma, and 7 of the species were taken
in the Straits. Papers by Schwengel &
McGinty (1942) and Schwengel (1951) added
2 new shallow water species of Calliostoma,
and Clench & Abbott (1943) treated 3 species
of Gaza known from the Straits area. Rehder
(1955) redescribed Turcicula imperialis Dall,
and discussed the relationships of Turcicula
to Lischkeia, Bathybembix, and Calliotropis.

Clench & Turner (1960) produced a com-
prehensive monograph of the Western Atlan-
tic Calliostoma, and included a section deal-
ing with species which were originally de-
scribed as Calliostoma, but are doubtfully in
that genus, or assigned to some other genus
entirely. In all, they dealt with 56 species of
which 23 are known from the Straits area.
Finally, Bayer (1971) reviewed 59 species of
molluscs from the tropical West Atlantic and
included 8 species of trochids (five from the
Straits).

A few lists of molluscs have been published
which include species of the Straits fauna.
The most important are Dall’s (1885, 1889b)
and Johnson's (1934). A work which is helpful
only as a list is Abbott (1974). Another useful
work is Pilsbry (1889) in the Manual of Con-
chology, in which he compiled the original de-
scriptions and citations for as many trochid
species as possible on a worldwide basis, and
brought together most of the illustrations then
available.

MATERIALS AND METHODS

Material for this study came from collec-
tions made by a variety of ships. The bulk of
these collections is deposited at the Univer-
sity of Miami and the U.S. National Museum,
with a lesser amount of material in the Muse-
um of Comparative Zoology, Harvard Univer-
sity. The major portion of the collections was
made aboard the USCGS BLAKE (1877-
1880), the U.S. Fish Commission Ship
ALBATROSS (1883-1887), John Hender-
son’s yacht EOLIS (1910-1917), the ATLAN-
TIS (1938-1939), and the R/V GERDA of the
University of Miami (1962-1972). Additional
specimens from the Caribbean were obtained
by the State University of lowa Expedition to
Barbados and Antigua (1918) with the launch
EOLIS jr, and by the University of Miami
aboard the R/V JOHN ELLIOTT PILLSBURY.

The collecting gear used by the expeditions
is quite varied. The BLAKE and ALBATROSS
used primarily the beam trawl and a modified
beam trawl known as the BLAKE trawl, which
fished equally well on either side. Several
types of dredges were also used upon occa-
sion aboard the BLAKE and ALBATROSS.
John Henderson, aboard the EOLIS and
EOLIS jr used, almost exclusively, a small
box-type dredge. The ATLANTIS used 10-ft
and 14-ft BLAKE trawls and 35-ft, 52-ft and
60-ft otter trawls. The GERDA employed sev-
eral types of gear, primarily the 10-ft otter
trawl or “try net.” A 16-ft otter trawl was used
briefly from the GERDA, but was soon dis-
carded since it was rather unwieldy aboard
the GERDA and it merely caught larger quan-
tities of species taken by the try net. Several
types of dredges were employed, including a
box dredge, pipe dredge and triangular
dredge, but their use was discontinued prima-
rily for reasons of economy. They did not ob-
tain large enough collections to warrant the
time and energy expended. An accidental bot-
toming of a 6-ft Isaacs-Kidd Midwater Trawl
obtained a rather rich collection of small mol-
luscs. For a detailed description of the
GERDA and her gear, see Devany (1969)
and Staiger (1970). The PILLSBURY worked
primarily in the Caribbean Sea, using the 10-ft
and 40-ft otter trawls, and occasionally a 5-ft
BLAKE trawl.

The dredges are, without doubt, the best
gear for obtaining the minute molluscs, includ-
ing those which burrow shallowly. However,
the area sampled is necessarily small, and in
deep-sea surveys, they are inadequate. The
BLAKE and beam trawls are better, but still

STRAITS OF FLORIDA TROCHIDAE 3

somewhat uneconomical for extensive use in
the deep-sea. Therefore, since the 1930's,
most work has been done with the otter trawl.
The limitation on the otter trawls is that, al-
though capturing the larger organisms ade-
quately, the very small organisms are often
washed through the mesh of the net and only
part are retained. It is difficult to make any
assumptions as to the relative abundance of
individuals at any station. The small molluscs
are also frequently overlooked in sorting the
catch, and unless the debris and sediment are
saved and sorted under magnification, many
specimens could be lost.

For the literature used in identifying the
specimens, see Literature Review section. In
addition to the primary literature, many
smaller, less comprehensive papers were
consulted to verify identifications, check syn-
onymies, and compile distributional data.
Types of several species were kindly loaned
by Dr. Kenneth J. Boss of the MCZ. Finally,
two trips were made to the USNM to examine
the types of all the Western Atlantic trochids
deposited there, and to compare many of the
RSMAS specimens with material in the
USNM collections. In addition to the Jeffreys
collection, the USNM collections contain most
of the material from the BLAKE and ALBA-
TROSS expeditions, the entire Henderson
collection, as yet largely unidentified, and the
State University of lowa Expedition collec-
tions. These afforded numerous lots of mate-
rial from the Straits of Florida and the Carib-
bean.

A WILD M-5 binocular dissecting micro-
scope was used for examination of all speci-
mens and a camera lucida attachment was
used for preliminary drawings of many of the
smaller species and comparison with similar
species. A WILD M-20 compound microscope
was used for examination of radular prepara-
tions.

Radulae were removed by soaking the
specimen in hot KOH to dissolve the tissue.
They then were washed and mounted in
Euparal on a microscope slide. Shell measure-
ments were made with dial calipers graduated
in tenths of millimeters. All measurements are
given in millimeters and depths are in meters.

All photographs were taken with a PENTAX
SP II 35mm SLR camera using KODAK
Panatomic-X film. A bellows attachment and
2x teleconverter were used when photograph-
ing specimens less than 10 mm in height. A
ROLLEI E-27 strobe unit was used for primary
lighting and a white card reflector was placed
behind the specimen for fill-in lighting.

Measurements given in the descriptions are
the total height of the specimen unless other-
wise noted.

Abbreviations used in the paper are as fol-
lows:

RSMAS—Rosenstiel School of Marine and
Atmospheric Science

USNM—U.S. National Museum of Natural
History

MCZ—Museum of Comparative Zoology,
Harvard University

ANSP—Academy of Natural Sciences, Phila-
delphia

UMML 30-0000—University of Miami Marine
Lab. gastropod accession number

G-0000—R/V GERDA Station number

P-0000—R/V PILLSBURY Station number

OT—Otter Trawl

IKMT—Isaacs-Kidd Midwater Trawl

J-S—Johnson-Smithsonian Deep-Sea Expe-
dition to the Puerto Rico Deep in 1933

SUI—State University of lowa Barbados-
Antigua Expeditions, 1918.

The synonymies cited in the Species Ac-
count are, for the most part, complete. Some
minor lists have been omitted, and recent
popular and semi-popular guides and identifi-
cation manuals have not been included with
the exception of Abbott's American Seashells
(1974). This was included since most of the
species treated here are listed, and the work
enjoys a very wide following, both amateur
and professional. With the exception of spe-
cies of Calliostoma and Gaza, all species
have been redescribed and figured since the
species are poorly known and the original de-
scriptions were often inadequate or mislead-
ing, and relatively inaccessible without an ex-
tensive literature search. Types of almost all
species were traced and examined. Those
which were not examined are noted under
Types section on the species description.

The Material Examined sections of the
species descriptions are in abbreviated form,
consisting of a vessel or expedition station
number followed by the number of specimens
in the lot and the museum accession number
of the lot. Miscellaneous collections, such as
those by the EOLIS, are accompanied by
complete data. Complete data for the abbre-
viated notations are included in the Appendix.

Area of Study.—For the purposes of this
study, the Straits of Florida are defined as fol-
lows: bounded on the north by 27*30'N, оп
the east by the Bahamas or 78°30'W, on the

4 QUINN

west by the Florida peninsula and out to
83°30’W, and on the south by the northern
coast of Cuba. The approaches to the Straits
are the Yucatan Channel, Nicholas Channel,
Santaren Channel, and the Northwest Provi-
dence Channel. This is a somewhat arbitrary
demarcation, selected primarily to agree with
previous studies of the fauna of the Straits
(Robins, 1968; Devany, 1969; Staiger, 1970;
Cairns, 1973; Messing, 1975). In these re-
ports, the various physical, geological and
hydrographical aspects of the Straits have
been extensively summarized. Therefore,
only the following brief description of the area
is presented:

The Straits of Florida are an arcuate, slop-
ing trough, separating the Florida Plateau
from the Bahama Platform and Cuba, and
forming the bed of the Florida Current. The
thalweg of the trough descends from a north-
ern sill located about 27°25’N at a depth of
just over 700 т. The slope is at first slight
(0.4 m/km), descending to a broad, flat pla-
teau with a depth of 860-878 m just north of
the Cay Sal Bank. In the Cay Sal area the
thalweg assumes a much steeper gradient
(up to 5m/km), descending to about
2800 m at its junction with the extreme south-
eastern Gulf of Mexico. The axis of the Straits
from Cay Sal to the Gulf of Mexico extends
roughly to the west. Here the bottom topog-
raphy also becomes very rugged.

The Yucatan Channel separates Cuba and
Yucatan and permits the passage of water
from the northwestern Caribbean Sea into the
Gulf systems and the Florida Current. The
southeastern Straits is divided into 2 subsidi-
ary channels, the Nicholas and Santaren
Channels, by the Cay Sal Bank. To the south-
east these 2 channels merge to form the Old
Bahama Channel which separates Cuba and
the Bahama Platform. The Northwest Provi-
dence Channel enters the Straits from the
northeast, dividing the Bahamas Platform into
the Great and Little Bahama Banks. To the
north of the Straits, the Blake Plateau extends
to the northeast and descends gradually to a
depth of about 1500 m, from whence the bot-
tom drops suddently to the floor of the Atlantic
(about 3700 m).

Detailed descriptions of the various physio-
graphic features of the Straits are presented
in Jordan & Stewart (1961), Jordan et al.
(1964), Kofoed & Malloy (1964) and Malloy &
Hurley (1970). Summaries of the hydrography
of the Straits may be found in Wennekens

(1959), Devany (1969) and Cairns (1973).
Messing (1975) gave an extensive summary
of all aspects of the oceanography of the
Straits.

SYSTEMATICS

The higher classification used in this study
is primarily based on that of Thiele (1929) and
modified by Keen (1960) and McLean (1971).

Phylum MOLLUSCA
Class GASTROPODA Cuvier, 1797
Subclass Prosobranchia A. Milne-Edwards, 1848
Order Archaeogastropoda Thiele, 1925
Suborder Trochina Cox & Knight, 1960
Superfamily Trochacea Rafinesque, 1815

Family Trochidae Rafinesque, 1815

Subfamily Margaritinae Stoliczka, 1868
Genus Margarites Gray, 1847
Genus Calliotropis Seguenza, 1903
Genus Lischkeia Fischer, 1879
Genus Euchelus Philippi, 1847
Genus Mirachelus Woodring, 1928
Genus Echinogurges gen. nov.

Subfamily Umboniinae Pilsbry, 1886
Genus Gaza Watson, 1879

Subfamily Calliostomatinae Thiele, 1924
Genus Calliostoma Swainson, 1840
Genus Dentistyla Dall, 1889

Subfamily Solariellinae Powell, 1951
Genus Solariella S. V. Wood, 1842
Genus Microgaza Dall, 1881

Subfamily Margaritinae Stoliczka, 1868
Genus Margarites Gray, 1847

Margarita Leach, 1819: 464 (non Leach,
1814).

Margarites Gray, 1847b: 268.

Eumargarita Fischer, 1885: 825.

Valvatella Melville, 1897: 472 (non Gray,
1857).

Type-species.—Trochus helicinus Fabric-
ius, 1780; by original designation, Gray,
1847b: 268.

Diagnosis.—Shell small, usually nacreous,
conical or rather depressed, smooth or spi-
rally striate, with rounded whorls, usually um-
bilicate. Radula rhipidoglossate; rhachidian
with a single, laterally serrate cusp; laterals 4
to 6, serrate on the outer edges; marginals
numerous, similar in size and form to the lat-
erals.

STRAITS OF FLORIDA TROCHIDAE 5

Subgenus Bathymophila Dall, 1881

Bathymophila Dall, 1881: 102; 1889a: 378;
1889b: 162.—Pilsbry, 1889: 306.—Johnson,
1934: 73.—Abbott, 1974: 37.

Type-species.—Margarita euspira Dall,
1881; by monotypy, Dall, 1881: 102.

Diagnosis.—Shell with or without a sub-
sutural row of nodules; columella broad, flat-
tened, granular in young specimens; umbili-
cus closed by callus.

Margarites (Bathymophila) euspira
(Dall, 1881)
Figs. 1,2

Margarita (?) euspira Dall, 1881: 44.

Margarita (Bathymophila) euspira: Dall,
1881: 102; 1889a: 378, pl. 32, fig. 8; 1889b:
162, pl. 32, fig. 8 (listed only; fig. from
1889a).—Pilsbry, 1889: 306, pl. 51, fig. 24;
pl. 47, figs. 1-3 (description from Dall,
1881; figs. from Dall, 1889a and Jeffreys,
1883).

Margarita (Bathymophila) euspira var. nitens
Dall, 1881: 102.

Trochus (Oxystele) euspira: Jeffreys, 1883:
98, pl. 20, fig. 6.—Watson, 1886: 68.

Trochus (Oxystele) euspira var. coronata
Jeffreys, 1883: 99.

Margarites (Bathymophila) euspira: Johnson,
1934: 73 (listed only).

Margarites (Bathymophila) euspirus: Abbott,
1974: 37, fig. 237 (listed only; fig. from Dall,
1889a).

Description.—Shell small (attaining a
height of about 7 mm), bluntly conical, pol-
ished, white with an underlying iridescence, of
about 6 rounded whorls. Protoconch small,
glassy, of about 112 whorls. First 2 whorls with
6 to 8 strong spiral cords which generally be-
come obsolete on later whorls; cord nearest
the suture often persisting as a row of obscure
to prominent nodules. Whorls following the
2nd generally smooth and polished, with only
fine growth lines. Base rounded; umbilicus
open in young specimens, filled by columellar
callus in mature specimens. Aperture oblique-
ly ovate; outer lip thin and simple; columella
thick, flattened, broad at its base, with a small
obscure tubercle above a shallow subterminal
hollow.

Holotype.—Not traced.

Type-locality.—BLAKE sta. 2, 23°14’М,
82°25'W, off Havana, Cuba, 1472 m.

Material examined.—Blake, sta. no. unre-
corded, Yucatan channel, 1170m; 1, MCZ
15705 МСЯ 7577.

Geographic distribution.—This is an
amphi-Atlantic species which occurs in the
Eastern Atlantic in Vigo Bay off northern Por-
tugal and in the Western Atlantic in the south-
ern Straits of Florida, the Yucatan Channel,
and the Virgin Islands.

Bathymetric range. —Known in the Eastern
Atlantic from 1353 to 2003 m, and in the
Western Atlantic from 713 to 1472 m.

Remarks.—This species is rather variable
in sculpture. The usual form is devoid of any
sculpture other than the row of obscure beads
at the suture. Some forms exhibit spiral cords
over the whole shell, some have a strongly
coronated subsutural cord (variety coronata
Jeffreys, 1883), and others are lacking the
subsutural band entirely (variety nitens Dall,
1881). The relationships of this species are
unclear at present. It appears to be closest to
the “Umbonium” bairdi of Dall, which is not
an Umbonium. M. euspira also bears a super-
ficial resemblance to Solariella lubrica Dall
(q.v.), but they are not closely related.
Whether or not M. euspira belongs in Marga-
rites must await examination of the radula.

Margarites (Bathymophila) bairdi
(Dall, 1889)
Figs. 3,4

Umbonium bairdii Dall, 1889a: 359, pl. 21,
figs. 6, 6a; 1889b: 160, pl. 21, figs. 6, 6a
(listed only; figs. from 1889a).—Pilsbry,
1889: 457, pl. 60, figs. 5, 6 (description and
figs. from Dall, 1889a).—Johnson, 1934: 74
(listed only). —Abbott, 1974: 40, fig. 270
(listed only; fig. from Dall, 1889a).

Description.—"Shell small, depressed
conic, white, polished, externally porcellan-
ous, internally slightiy nacreous; nucleus
globular, dextral; whorls five or more. Radiat-
ing sculpture of occasional faint impressed in-
cremental lines; spiral sculpture of occasional
microscopic striae, and a single strap-like
band appressed to the suture, and bearing
numerous flattish squarish nodules or eleva-
tions, which coronate the whorls; periphery
rounded, base rounded, depressed in the
centre, which is nearly filled with a mass of
white callus having a very finely granular sur-
face. Aperture ovate, margin simple, thin,
oblique.” (Dall, 1889a: 359.)

6 QUINN

Il

FIGS. 1-6. 1-2. Margarites (Bathymophila) euspira (Dall): BLAKE sta. off Yucatan, h = 4.9 mm, d
5.6 mm. 3-4. Margarites (Bathymophila) bairdi (Dall) (holotype): ALBATROSS sta. off “Florida Reefs,” h
3.9 тт, d = 5.3 mm. 5-6. Calliotropis (Calliotropis) ottoi (Philippi): USNM 179612.

Il

STRAITS OF FLORIDA TROCHIDAE 7

Holotype.—USNM 95064, from an unspe-
cified ALBATROSS Station off the Florida
Reefs.

Type-locality and Material examined.—
ALBATROSS (sta. number unspecified), off
the Florida Reefs; 1, USNM 95064 (holotype).

Geographic distribution.—Known only
from the Straits of Florida and the Yucatan
Channel.

Bathymetric range.—366 to 1170 m.

Remarks.—Several workers have com-
mented that this species is probably not an
Umbonium, an opinion with which | agree. U.
bairdi appears to have an affinity with Marga-
rites (Bathymophila) euspira Dall, at least in
external shell characters. Both have spiral
cords on the first whorls, the subsutural row of
beads in U. bairdi is quite similar to that exhib-
ited by M. euspira, especially the coronated
forms, and the peculiar columellae are re-
markably alike. The granulated surface of the
columella of bairdi is also present in immature
specimens of euspira. U. bairdi differs from
M. euspira primarily in having a more conical
shape with the sutures rather indistinct and
not strongly impressed, having weaker spirals
on the first whorl, and having the columella
slightly different. The similarities of the 2 spe-
cies lead me to believe that they should be
congeneric.

Genus Calliotropis Seguenza, 1903

Calliotropis Seguenza, 1903: 462.

Solariellopsis Schepman, 1908: 53 (non
Gregorio, 1886).

Margarita (partim), Auctt. (non Gray, 1847a).

Solariella (partim), Auctt. (non S. V. Wood,
1842).

Type-species.—Trochus ottoi Philippi,
1844; by original designation, Seguenza,
1903: 462.

Diagnosis.—Shell small to moderate in
size, thin, iridescent, inflated, widely umbili-
cate, sculptured with spiral rows of sharp
tubercles. Radula with rhachidian, 3 subequal
laterals and 1 rudimentary lateral, and 12 to
21 rather small marginals.

Remarks.—Calliotropis was erected by
Seguenza for the fossil trochid Trochus ottoi
Philippi (Figs. 5, 6). C. regalis (Verrill & Smith)
(Figs. 7, 8) has been considered a synonym
of ottoi since shortly after its description.
However, as Rehder & Ladd (1973) have
pointed out, the 2 are very closely related but
entirely distinct species. The numerous mar-

ginal teeth of the radula show it to be in the
Margaritinae rather than in the Solariellinae
where many of its species have been placed
as recently as 1974 (Abbott, 1974). Callio-
tropis recently has been considered a sub-
genus of Lischkeia Fischer, 1879, but the
large, rather heavy shell, umbilical callus, and
reflected inner lip of the latter seem to be suf-
ficient characters for generic separation.

Subgenus Solaricida Dall, 1919

Solaricida Dall, 1919: 361.—Keen, 1960:
1262.—McLean, 1971: 331.

Type-species. — Solariella (Solaricida)
hondoensis Dall, 1919; by monotypy, Dall,
1919: 361.

Diagnosis.—Shell generally more inflated
than Calliotropis s. s., with a wider and deeper
umbilicus.

Calliotropis (Solaricida) aeglees
(Watson, 1879)
Figs. 141512

Trochus (Margarita) aeglees Watson, 1879:
704: 1886: 81, pl. 5; tig. 10:

Trochus (Margarita) ottoi: Jeffreys, 1883: 98
(partim).

Margarita (Solariella) aegleis: Dall, 1889a:
379 (partim); 1889b: 164 (partim; listed
only).—Pilsbry, 1889: 315, pl. 66, figs. 18,
19 (partim; description from Watson, 1879;
figs. from Watson, 1886).

Solariella (Machaeroplax) aegleis aegleis:
Johnson, 1934: 71 (partim?; listed only).
Solariella aegleis aegleis: Abbott, 1974: 41

(partim; listed only).

Description.—Shell small (attaining a
height of about 5mm), broadly conical, of
about 6 whorls, white with ап underlying
nacreous lustre. Protoconch small, promi-
nent, glassy, of about 172 whorls. First whorl
with strong axial riblets which disappear on
later whorls. Sculpture on later whorls of spire
consisting of 2 spiral rows of rounded, axially
produced tubercles. There is no connection
between the tubercles of 1 row and those of
the other, but an obscure spiral cord connects
the tubercles of each individual row. Upper
row very close to the suture line and sepa-
rated from the second row by a fairly broad,
flat area. Body whorl bears a third carina just
below the second and forms the whorl periph-
ery. Distance between the lower 2 carinae
about half that between the upper 2, giving

8 QUINN

FIGS. 7-14. 7-8. Calliotropis (Calliotropis) regalis (Verrill & Smith): USNM 44681. 9-10. Calliotropis vaillanti
Fischer: USNM 94958. 11-12. Calliotropis (Solaricida) aeglees (Watson (syntype): CHALLENGER-24, h =
6.9 mm, d = 7.3 mm. 13-14. Calliotropis (Solaricida) lissocona (Dall) (holotype): BLAKE-47, h = 5.6 mm, d
= 5.2 mm.

STRAITS OF FLORIDA TROCHIDAE 9

the whorl a sloping contour. Base rounded,
narrow, with 3 spiral cords. Outer spiral ob-
scurely beaded, the middle 1 smoothish, and
the inner set with strong rounded tubercles,
forming the umbilical margin. Spaces between
the basal cords concave with rather strong
radial plications which continue up into the
umbilicus. Umbilicus very wide but sharply
constricted within, deep. Aperture oblique,
rounded, quadrangular; lips thin, inner lip re-
flected slightly. Columella thin, concave
above and below a blunt tooth which is the
termination of a spiral ridge extending into the
aperture.

Holotype.—None selected. The syntype
series is in the British Museum (Natural His-
tory), cat. nos. 87.2.9.311-314, and 1 syntype
is in the USNM, cat. no. 118787; all are from
CHALLENGER sta. 24.

Type-locality.—CHALLENGER sta. 24,
18°38'30"N, 65°05’20”W, off Culebra Island,
Virgin Islands, 713 m.

Material examined.—Straits of Florida:
G-1008; 1, UMML 30-8044.—G-1096; 1,
UMML 30-8036.—Caribbean: J-S sta. 67; 13,
USNM 429422—\-$ sta. 93; 2, USNM
429539.— CHALLENGER sta. 24; 1, USNM
118787 (syntype).

Geographic distribution —Known only
from the Straits of Florida near Cay Sal Bank,
off the Dry Tortugas, and from off Puerto Rico
and the Virgin Islands.

Bathymetric range.—C. aeglees occurs in
rather deep water, from 350 to 732 m.

Remarks.—There has been an extraordi-
nary amount of confusion surrounding this
species. In 1879, Watson described C.
aeglees, Trochus lima (=C. rhina Watson,
1886), Echinogurges clavatus and E. rhysus
as Trochus (Margarita) species. Dall (1881)
reported aeglees from the BLAKE dredgings
and included Solariella lamellosa as a syno-
nym. This was a mixed lot consisting primarily
of specimens of S. /amellosa, S. pourtalesi
Clench & Aguayo, and probably some speci-
mens of Calliotropis calatha (Dall), C. rhina,
and E. clavatus, all of which he considered
merely forms of one another. In 1883, J. G.
Jeffreys placed aeglees into synonymy with
C. ottoi (Philippi), a Pliocene fossil from Italy.
Watson (1886) disagreed with Dall’s opinion
(1881) that $. lamellosa was synonymous
with aeglees, and he also expressed doubt
that Jeffreys’ identification of aeglees with С.
regalis (Verrill & Smith) was correct. Dall, in
the meantime, had obtained the Jeffreys col-
lection, and, on the basis of this additional
material, modified his earlier views some-

what. He removed S. /amellosa and S.
pourtalesi (as S. amabilis Jeffreys) from syn-
onymy with aeglees, but added a new variety,
lata (=C. calatha Dall). This variety was intro-
duced as a nomen nudum, and an examina-
tion of his specimens reveals another mixed
lot. Along with aeglees, Dall mentioned 2 lots
of fossils from the Tertiary of Belgium and 2
from Italy, and a specimen taken by the
TALISMAN expedition. There seems to have
been a transposition of labels of the fossil lots
which Dall was unable to straighten out, and
as a result, he was faced with a problem in as-
signing names to the specimens. Apparently
the labels of a lot of Trochus peregrinus Libas-
si (USNM94960, not 94952) and a lot of “Solari-
um” turbinoides Nyst (=Solariella maculata S.
V. Wood; USNM 94952, not 94960) were trans-
posed before Dall examined them. He decid-
ed that peregrinus was the same as his vari-
ety lata. They are closely related, but definite-
ly not conspecific. He continued to believe,
however, that rhina, clavatus, rhysus, and his
“wide form” lata were all varieties of aeglees.
One factor which probably contributed to
Dall's confusion was the rather poor quality of
the illustrations of each species in the CHAL-
LENGER report (Watson, 1886). The speci-
men from the TALISMAN, labeled “Trochus
ottoi” by Jeffreys, is an Eastern Atlantic spe-
cies, Calliotropis vaillanti (Fischer) (Figs. 9,
10), although later in his discussion of ottoi,
Dall stated that he had never seen a speci-
men of this species. All works since Dall
(1889) have followed his opinions uncritically,
neither noticing that the variety “lata” was a
nomen nudum, nor that this form is the same
as C. calatha Dall.

C. aeglees differs from calatha in having (1)
the spire more conical than scalar; (2) the
subsutural carina abutting the suture rather
than separated from it by a narrow shelf; (3)
the mid-whorl carina lower on the whorl; and
(4) the tubercles of all 3 carinae more equal in
size, less prominent, and more rounded than
in calatha.

As redefined here, C. aeglees has a far
more restricted range than previously sup-
posed, and is rather rare, especially when
compared to the number of specimens of
calatha available.

Calliotropis (Solaricida) calatha
(Dall, 1927)
Figs. 15-20, 23-26

Margarita (Solaricida) aegleis var. lata Dall,
1889a: 380 (partim); 1889b: 164 (listed

10 QUINN

FIGS. 15-20. 15-16. Calliotropis (Solaricida) calatha (Dall) (syntype): ALBATROSS-2415, h = 4.1 mm, d
= 5.0 mm. 17-18. Calliotropis (Solaricida) calatha (Dall) (“уаг. lata” Dall): С-1312, В = 4.7 mm, d =
6.3 mm. 19-20. Calliotropis (Solaricida) calatha (Dall): G-1008, h = 4.5 mm, d = 5.9 mm.

STRAITS OF FLORIDA TROCHIDAE 11

only).—Johnson, 1934: 71 (listed only). All
are nomina nuda.

Solariella calatha Dall, 1927a: 128.—John-
son, 1934: 72 (listed only). —Abbott, 1974:
41 (listed only).

Solariella aegleis aegleis: Abbott, 1974: 41
(partim; listed only).

Description.—Shell attaining a height of 9
to 10mm, broadly conical, carinated, spire
high or slightly depressed, widely umbilicate,
highly sculptured, of about 6 whorls, white
with an underlying nacreous lustre. Proto-
conch small, prominent, glassy, of 172 whorls.
Spire bearing 2 (occasionally 3) carinae set
with numerous sharp, axially produced tuber-
cles; another similar carina becomes visible
on the body whorl. Tubercles of each carina
connected by a fine spiral thread; number of
tubercles on lower 2 carinae may vary greatly
in a series of specimens, but usually is about
60 on the last whorl. Upper carina separated
from the suture by a narrow shelf and bears
about 20 to 30 sharp tubercles. Periphery of
the whorl may be formed by either or both of
the lower 2 carinae. Middle carina lies slightly
closer to lower carina than to subsutural
carina. Occasional specimens may have an-
other carina intercalated below the subsutural
one. Base with 3 to 4 finely beaded cords, the
innermost of which is somewhat stronger and
more coarsely beaded and defines the umbili-
cal margin. Surface of the whorls between the
spiral sculpture may be smooth (except for
fine growth lines) to highly corrugated axially.
Umbilicus very wide, deep, and strongly con-
stricted within; walls slightly concave, axially
rugose, and often with fine spiral cords. Aper-
ture strongly oblique, ovate; lips thin, inner lip
slightly reflected over the umbilicus. Columel-
la strongly arched, slightly thickened, usually
ending in a strong, blunt tooth, below which
the lip is concave, rounding into the basal lip.
Periostracum thin, brown.

Holotype.—None selected. Syntype series
is in the USNM, cat. no. 108424, 13 speci-
mens from ALBATROSS sta. 2415.

Type-locality.—ALBATROSS sta. 2415,
30°44'N, 79°26’W, 805 т.

Material examined.—ALBATROSS sta.
2415; 13, USNM 108424 (syntypes).—
ALBATROSS sta. 2668; 18, USNM
108121.—Straits of Florida: G-1312; 1, UMML
30-8091.—Off Fowey Rocks, Miami, Rush
Coll., 850m; 1, USNM 83034.—G-289; 1,
UMML 30-8100.—G-1018, 2, UMML
30-8047.—G-1008; 1, UMML 30-8045.—

EOLIS sta. 329 off Sambo Reef, 247 m: 1,
USNM 450557.—G-1015; uF UMML
30-8035.—G-967; 1, UMML 30-8034—
BLAKE sta. 2; 1, USNM 94955.—Yucatan
Channel: BLAKE, sta. no. unrecorded, near
Саре San Antonio, Cuba, 1170 т; 1, USNM
94954.—Caribbean: Р-604; 4, UMML
30-8101.—P-605; 2, UMML 30-8102 —
P-607; 2, UMML 30-8103.—Off Cour del
Padre, Cuba, 1166 т; 4, USNM 94956.—P-
1225; 5, UMML 30-8104.—J-S sta. 67; 4, ex
USNM 429422.—J-S sta. 94; 2, USNM
429923.—P-919; 5, UMML 30-8105.—P-929;
2, UMML 30-8106.—P-905; 4, UMML
30-8107.—BLAKE sta. 230; 1, USNM
94957.—P-861; 9, UMML 30-8108.—P-846;
1, UMML 30-8109.—P-754; 2, UMML
30-8110.

Geographic distribution.—From off Geor-
gia south through the Straits of Florida and
the Yucatan Channel, and throughout the
Caribbean.

Bathymetric range.—The possible range is
18 to 1574 m, but specimens are generally
found in about 500 to 1000 m. The station
which records 18 meters as the shallowest
depth (P-861) spanned a total depth range of
726 meters (18-744 m); otherwise the spe-
cies is found almost exclusively in depths ex-
ceeding 500 m.

Remarks.—See Remarks section under C.
aeglees. This species has been cited under
the name “Solariella” aegleis lata since Dall's
mention of the name in 1889. This was a
nomen nudum and has never been validated,
so the name cannot stand for the species.
However, examination of the specimens of
“lata” and C. calatha (Dall, 1927) inthe USNM
has revealed that the two are conspecific, and
the species therefore takes the later name.

This is an extremely variable species, not
only over its whole range, but within individual
populations. The elevation of the spire, the
distinctness of the axial sculpture, the number
of tubercles on the carinae, and the width of the
umbilicus are all involved in the variation. As
different as any two specimens seem, there
appears to be a “connecting link” throughout
a long series of specimens. It is at present
impossible to separate any of the forms satis-
factorily into even subspecies since there is
no consistent pattern in the variation either
geographically or bathymetrically.

Two specimens are worthy of note. One
specimen from С-23 (25°32’N, 79°44’W,
477-238 m, UMML 30-8024) and 1 from P-
741 (11°47.8'N, 66°06.8’W, 1052-1067 m,

12 QUINN

FIGS. 21-28. 21-22. Calliotropis (Solaricida) actinophora (Dall) (holotype): ALBATROSS-2751, h =
7.4 mm, d = 8.4mm. 23-24. Calliotropis (Solaricida) calatha (Dall): P-605, h = 6.75 тт, d = 7.7 mm.
25-26. Calliotropis (Solaricida) calatha (Dall): P-846, h = 9.1mm, d = 9.2mm; 27-28. Calliotropis
(Solaricida) rhina (Watson): G-966, h = 7.0 mm, d = 6.0 mm.

STRAITS OF FLORIDA TROCHIDAE 13

UMML 30-6808) are possibly specifically dis-
tinct. They have peripheral carinae with ex-
tremely closely-set, scalelike tubercles, a
rather narrow, vertically-walled umbilicus, and
slightly more elevated spire, but because C.
calatha is so variable and the specimen from
off Cour del Padre, Cuba (USNM 94956) ap-
proaches this form, | am reluctant to erect a
separate taxon for these shells until more
material is available for study.

Calliotropis (Solaricida) rhina
(Watson, 1886)
Figs. 27,28

Trochus (Margarita) lima Watson, 1879: 703
(non Philippi, 1844).

Trochus (Margarita) rhina Watson, 1886: 80,
pl. 5, fig. 1 (nom. nov. for T. (M.) lima Wat-
son, 1879).

Margarita (Solariella) aegleis var. (?) rhina:
Dall, 1889a: 380; 1889b: 164 (listed
only).—Pilsbry, 1889: 316, pl. 64, figs. 51,
52 (description from Watson, 1879; figs.
from Watson, 1886).

Solariella (Machaeroplax) aegleis
Johnson, 1934: 71 (listed only).
Solariella aegleis aegleis: Abbott, 1974: 41

(partim; listed only).

rhina:

Description.—Shell attaining a height of
more than 10 mm, conical, spire rather ex-
tended, carinated, widely umbilicate, of 6% to
7 whorls, white with an underlying irides-
cence. Protoconch smooth, glassy, promi-
nent, of about 112 whorls. There are 2 carinae
on the spire with a third becoming apparent
on the body whorl; these are set with many
sharp, conical tubercles. Upper carina sepa-
rated from the suture by a narrow, flat shelf;
tubercles are strongest on this carina and are
connected by a fine spiral cord. Below the
subsutural carina are 2 stronger carinae form-
ing the periphery, the lower of which defines
the base. These carinae have about twice as
many, finer tubercles as the subsutural
carina. Base rounded, with 3 or 4 finely bead-
ed spiral cords, the innermost of which de-
fines the umbilicus. Axial sculpture of strong
lamellar ribs on the first postnuclear whorl, but
thereafter of only fine growth lines, which may
become stronger near the umbilicus and
ascend into the umbilicus. Umbilicus rather
wide, deep, with convex walls which may bear

1 or 2 fine spiral cords. Aperture slightly ob-
lique, ovate; outer lip thin and angled by the
Carinae; inner lip thin and slightly reflected:
columella smooth, straight, rounding to meet
the outer lip. Periostracum rather heavy,
brown.

Holotype.—None selected. The syntypes
are probably in the British Museum (Natural
History). Watson mentioned 1 specimen in
particular as “an almost exceptionally fine
specimen from Station 78” which probably
should be chosen as lectotype.

Type-locality.—CHALLENGER sta. 78,
37°26'М, 25°13’W, off San Miguel, Azores in
1829 m, herein restricted.

Material examined.—ALBATROSS sta.
2384; 1, USNM 93812.—Straits of Florida: G-
190; 1, UMML 30-7748.—G-23; 1, UMML 30-
8039.—G-368; 1, UMML 30-8027.—G-1106:
1, UMML 30-8096.—G-126; 1, UMML
30-8040.—G-966; 1, UMML 30-8093. —
G-439; 1, UMML 30-6971.—BLAKE sta. 2; 2,
USNM 94950.—P-605; 6, UMML 30-8111.—
P-607; 5, UMML 30-8112.—ALBATROSS
sta. 2150; 2, USNM 93855.—P-1255; 4,
UMML 30-8113.—P-1256; 3, UMML
30-8114.—P-1261; 6, UMML 30-8115. —
CHALLENGER sta. 24; 1, ex USNM
118787.—P-988; 3, UMML 30-81 16.—P-919;
1, UMML 30-8117.—P-904; 1, UMML
30-8118.—P-861; 3, UMML 30-8119. —
P-754; 2, UMML 30-8120.—P-766; 1, UMML
30-8121.

Geographic distribution. —C. rhina is an
amphi-Atlantic species; it is recorded from off
the Azores in the Eastern Atlantic, and the
Gulf of Mexico, the Straits of Florida and Car-
ibbean.

Bathymetric range.—As in C. calatha, the
possible depth range is from only 18 m to over
1800 m. Disregarding the 18 m record (since
the station covered a vertical distance of
726 m), the species is usually taken in depths
of 500 to 800 m.

Remarks.—C. rhina is very closely related
to C. aeglees (Watson) and C. calatha (Dall),
but it is much more elevated than either of
those two species. It is much less sculptured
than calatha, the aperture is less oblique, and
the columella never has the tooth as in
calatha. C. rhina is an extremely widespread
deep-sea Atlantic species and its characters
are remarkably conservative throughout its
occurrence, which is in sharp contrast to
calatha.

14 QUINN

Calliotropis (Sotaricida) lissocona
(Dall, 1881)
Figs. 13,14

Margarita lissocona Dall, 1881: 41.

Margarita (Solariella) lissocona: Dall, 1889a:
381, pl. 21, figs. 8, 8a; 1889b: 164, pl. 21,
figs. 8, 8a (listed only; figs. from 1889a).—
Pilsbry, 1889: 322, pl. 48, figs. 23, 24 (de-
scription from Dall, 1881; figs. from Dall,
1889a).

Solariella (Machaeroplax) lissocona: John-
son, 1934: 72 (listed only).

Solariella lissocona: Abbott, 1974: 41, fig. 288
(listed only; fig. from Dall, 1889a).

Description.—Shell attaining a height of
6.3 mm, conical, highly iridescent, carinate,
umbilicate, of about 6 whorls. Protoconch
small, glassy, of a little more than 1 whorl.
Just below the suture is a spiral row of small
conical beads connected by afinethread. From
this the whorl slopes flatly to the peripheral
carina which is formed by a double row of
beads similar to those of the subsutural row.
The beads of a single row are connected by a
fine spiral thread, and the beads of 1 row are
semi-fused with their counterparts in the
other. Base somewhat convex with 2 strong,
sharp, undulate spiral cords in the middle and
a strongly beaded cord defining the umbilical
margin. Axial sculpture of strong riblets on the
first 2 post-nuclear whorls, and thereafter only
of fine growth lines. Umbilicus rather wide,
deep, strongly constricted within. Aperture
subquadrate; outer lip thin, simple; inner lip
thin and very slightly reflected; columella
slightly oblique, a little arched, ending in an
obscure tooth from which the lip curves into
the basal lip. Fresh specimens with traces of a
brown periostracum.

Holotype.—USNM 214282, from BLAKE
sta. 47.

Type-locality.—BLAKE sta. 47, 28°42'N,
80°40'W, off the Mississippi Delta, in 587 m.

Material examined.—Gulf of Mexico:
BLAKE sta. 47; 1, USNM 214282 (holo-
type) —ALBATROSS sta. 2398; 1, USNM
93839.—Straits of Florida: G-967; 1, UMML
30-8122.—Caribbean: Р-776; 2, UMML 30-
8123.

Geographic distribution —Known from 2
stations in the northern Gulf of Mexico, 1 in
the Straits of Florida near the Marquesas
Islands, and 1 in the southern Caribbean off
Colombia.

Bathymetric range.—From 408 to 587 m.

Remarks.—This is a beautiful species, ap-

parently most closely related to C. aeglees
(Watson) from which it differs in being small-
er; the peripheral carina is composed of a
double row of tubercles more closely apposed
than in aeg/ees, and the columella has only a
very slight thickening rather than the strong
tooth of C. aeglees. C. lissocona is a rare,
although seemingly rather widespread, spe-
cies and it will probably turn up in other parts
of the Caribbean in depths of about 500 m.

Calliotropis (Solaricida) actinophora
(Dall 1890)
Figs. 21,22

Margarita (Solariella) actinophora Dall, 1890:
353; pl. 12. figs. 8, 11.

Solariella actinophora: Abbott, 1974: 41, fig.
295 (listed only; fig. from Dall, 1890).

Description.—Shell attaining a height of
9 mm, thin, inflated, spire depressed, umbili-
cate, of 5—6 whorls, highly nacreous when
fresh, otherwise white. Protoconch small,
glassy, protuberant, of about 1% whorls.
Whorls of the spire with 3 fine, sharp spiral
threads; the upper is very fine and very close
to the suture; the second is often the strong-
est and placed just above mid-whorl; the third
may be as strong as the second and is just
above the succeeding suture. A fourth spiral,
hidden by the suture on the spire, forms the
periphery of the last whorl. Spiral sculpture is
crossed at regular intervals by axial ribs which
are of the same character as the spirals.
Axials are continuous on the first 3 whorls,
forming a reticulate pattern with the spirals;
otherwise, the axials are restricted to sharp,
close-set plications radiating a short distance
from the suture and likewise from the umbili-
cus. The beading of the upper 2 spirals is
coarsest, with the beading becoming much
finer on the lower spirals. Base tumid, usually
with 3 rather weak, beaded spiral cords be-
tween the periphery and a strongly tubercled
inner cord which bounds the umbilicus. Umbil-
icus wide, deep, walls nearly vertical with axial
corrugations. Aperture rounded; outer lip thin,
simple; inner lip thin, very slightly reflected;
columella straight, thin, with a weak to strong
tooth at the middle in mature specimens.
Periostracum thin, olive-brown.

Holotype.—USNM 96468,
TROSS sta. 2751.

Type-locality.—ALBATROSS sta. 2751,
16°54'М, 63°12’W, south of St. Kitts, Lesser
Antilles, in 1257 m.

from ALBA-

STRAITS OF FLORIDA TROCHIDAE 15

Material examined.—Straits of Florida:
G-824; 1, UMML 30-7701.—G-1111; 1,
UMML 30-8037.—G-1112; 2, UMML
30-8038.—G-129; 1, UMML 30-8026.—
G-366; 1, UMML 30-8124.—G-375; 1, UMML
30-8029.—G-374; 3, UMML 30-8028.—
G-128; 9, UMML 30-8125.—G-965; 6, UMML
30-7761.—G-964; 3, UMML 30-7743; 7,
UMML 30-8033.—G-449; 2, UMML
30-6976.—G-448; 2, UMML 30-8126.—
G-963; 10, UMML 30-7694.—G-960; 5,
UMML 30-8032.—G-959; 1, UMML 30-8031.

Geographic distribution —The Gulf of
Mexico, the Bahamas and the Straits of Flor-
ida, south through the Antillean arc, and
South America from Tobago to the Rio de la
Plata, Argentina.

Bathymetric range.—This species has a
possible depth range of 21 to 1863 m, but is
generally rather rare in depths less than
1000 m, and rather common between 1000
and 1500 m.

Remarks.—C. actinophora has been rather
rare in most collections, and has been over-
looked in the literature to a great extent. Since
its description in 1890, it has been cited only
in the semi-technical book American Sea-
shells (Abbott, 1974). However, the various
ships from RSMAS have taken this species
throughout the Caribbean area. It is closely
related to C. infundibulum (Watson, 1879), a
much larger, more elevated species which is
also found in the Western Atlantic. C.
actinophora was taken by the ALBATROSS
at station 2764 off the Rio de la Plata in 11%
fathoms (21 m). | am very reluctant to accept
the depth here since actinophora is rarely
taken in depths much shallower than
1000 m, and other species collected at this
station occur normally at great depths them-
selves (e.g., Seguenzia trispinosa Watson,
1879).

Genus Lischkeia Fischer, 1879

Lischkeia Fischer, 1879: 419.
Margarita (partim): Auctt. (non Leach, 1814).
Calliostoma (partim): Pilsbry, 1889: 332.

Type-species.—Trochus moniliferus Lam-
arck, 1816; by original designation, Fischer,
1879: 419.

Diagnosis.—Shell large, elevated trochoid,
sculptured by nodulous spiral ribs, umbilicus
partly or wholly covered by a thin callus,
columella arched and smooth, base flattened
to slightly convex.

Subgenus Turcicula Dall, 1881

Turcicula Dall, 1881: 42; 1889a: 376; 1889b:
162; 1908: 348; 1909: 98.—Fischer, 1885:
827.—Pilsbry, 1889: 330.—Cossmann,
1918: 254, 263.—Taki & Otuka, 1942:
93.—Rehder, 1955: 222.—Abbott, 1974:
39.

Type-species.—Margarita (Turcicula) im-
perialis Dall, 1881; by monotypy, Dall, 1881:
42.

Diagnosis.—Shell rather thin, sutures
deep, sculpture of spiral rows of nodules and
axial vermiculate lamellar growth ridges, outer
lip reflexed at maturity, umbilicus covered.

Remarks.—This genus is represented by a
single species from the Caribbean. The place-
ment of Turcicula has been a matter of con-
jecture since it was first proposed, and will
remain so until a specimen with soft parts is
available for study. However, in view of the
obvious similarities of Lischkeia monilifera
and Turcicula imperialis, | prefer to retain
Turcicula as a subgenus of Lischkeia.

Lischkeia (Turcicula) imperialis (Dall, 1881)
Figs. 29,30

Margarita (Turcicula) imperialis Dall, 1881:
42; 1889a: 376, pl. 22, figs. 1, 1a; 1889b:
162, pl. 22, figs. 1, 1a (listed only; figs. from
1889a).—Pilsbry, 1889: 330, pl. 49, figs. 29,
30 (description from Dall, 1881; figs. from
Dall, 1889a).

Turcicula imperialis: Johnson, 1934: 70 (list-
ed only.) —Rehder, 1955: 223, pl. 12, figs.
1-9.—Keen, 1960: 1256, figs. 163 (12a,b).

Lischkeia deichmannae Bayer, 1971: 121,
fig. 5.

Lischkeia (Turcicula)
1974: 39, fig. 262.
Calliostoma (Turcicula) imperialis: Humph-

rey, 1975: 60, pl. 5, fig. 12.

Description.—See Rehder, 1955; Bayer,
1971.

Holotype.—MCZ 7575, from off Cuba,

66 m.

Material examined.—ALBATROSS sta.
2349: 1, USNM 94968.—G-897; 1, UMML 30-
7727.—P-889; 1, USNM 700003 (holotype of
L. deichmannae).

Geographic distribution —From the south-
ern Straits of Florida off Cuba, Arrowsmith
Bank off Yucatan, south and east to the Lesser
Antilles.

imperialis: Abbott,

16 QUINN

FIGS. 29-38. 29-30. Lischkeia (Turcicula) imperialis (Dall) (holotype of L. deichmannae Bayer): P-889, h =
55.0 тт, d = 44.5 mm. 31-32. Lischkeia (Turcicula) imperialis (Dall): ALBATROSS-2349, h = 15.0 тт, d
= 12.0 mm (immature specimen with spire and body whorl broken). 33-34. Mirachelus clinocnemus Quinn,
n. sp.: SUI-18, h = 3.4 mm, d = 2.6 mm. 35-36. Mirachelus corbis (Dall): G-56, h = 4.6 mm, d = 3.7 mm.
37-38. Euchelus guttarosea Dall: EOLIS-315, h = 2.5 mm, d = 2.4 mm.

STRAITS OF FLORIDA TROCHIDAE 17

Bathymetric range.—Prior to 1975 this
species was known from depths of 55-91 to
403 m indicating a relatively deep habitat.
Humphrey (1975) reported a specimen taken
on a beach on Barbados, so perhaps the spe-
cies inhabits depths considerably shallower
than previously believed.

Remarks.—This species was known only
from 2 broken and immature specimens until
Rehder (1955) reported a mature specimen
taken near St. Vincent, Lesser Antilles. In the
same paper he redescribed imperialis in light
of the new material, reviewed the history and
supposed relationships of Turcicula, and
concluded that it was of generic standing.
Bayer (1971) based his L. deichmannae on
an almost perfect specimen of imperialis and
noted its striking similarity to the type species
of Lischkeia, L. monilifera. \t is this similarity
which prompts me to follow Wenz (1938) in
placing Turcicula as a subgenus of Lischkeia.

Genus Euchelus Philippi, 1847

Euchelus Philippi, 1847a: 20.
Monodonta (partim): Auctt.
Trochus (partim): Auctt.

Type-species.—Trochus quadricarinatus
Holten, 1802; by subsequent designation,
Herrmannsen, 1847: 430.

Diagnosis.—Shell solid, turbinate, with
spiral beaded cords; umbilicus open or
closed; aperture ovate, outer lip thickened,
lirate within; columella thickened, with a tooth
at its base.

Euchelus guttarosea Dall, 1889
Figs. 37,38

Euchelus guttarosea Dall, 1889a: 382, pl. 33,
fig. 7; 1889b: 164, pl. 33, fig. 7 (listed only;
fig. from 1889a).—Johnson, 1934: 73 (list-
ed only).—Abbott, 1974: 38, fig. 258.

Euchelus (Euchelus) guttarosea: Pilsbry,
1889: 443, pl. 51, fig. 21 (description and
fig. from Dall, 1889a).

Description.—Shell small (attaining a
height of about 6 mm), solid, imperforate, with
about 5 rounded, highly sculptured whorls.
Protoconch depressed, small, glassy, of
about 112 whorls. Spiral sculpture consists of
3 strong cords on the spire with a 4th appear-
ing on the body whorl and forming the whorl
periphery; smaller, intercalary spirals are
usually present; base with 4 to 7 slightly nodu-
lous cords. Axial sculpture on the first post-

nuclear whorl of fine, sharp retractive riblets,
becoming stronger on the later whorls; these
form strong nodules on the spirals, and with
the spirals form a strong reticulate pattern on
the whorls. Aperture ovate, thickened within,
with 7 to 8 strong lirations ending in strong
denticles; columella short, straight, thickened,
with a strong tooth near its base. Color white,
often with discrete spots of red on the major
Spirals.

Holotype.—USNM 54774, from Nassau,
New Providence Island, Bahamas.

Material examined.—Bahamas: Nassau,
New Providence Is.,; 1, USNM 54774 (holo-
type).—Straits of Florida: EOLIS sta. 329, off
Sambo Reef, 247 m; 1, ex USNM 438325; 12,
USNM 450556.—EOLIS sta. 330, off Sambo
Reef, 220 m; 1, USNM 450559.—EOLIS sta.
333, off Key West, 201 m; 1, USNM 450534.
—BLAKE sta. no. unrecorded, off Havana,
Cuba, 823 m; 1, USNM 95047.

Geographic distribution —The Bahamas,
southeast Florida, and south through the
Antilles to Barbados.

Bathymetric range.—This species, like all
the others of the genus, is primarily a shallow
water species, occurring below the 100m
level only as dead shells. Deeper records are
usually in the vicinity of a sharp drop-off, and
shells are washed down the slope to as deep
as 823 m.

Remarks.—The shells from deep water are
all dead and few exhibit the rose-colored
patches often seen in the shallow water
forms. Whether this is due to wear of the shell
is hard to say, but many of the fresher speci-
mens from deeper water are pure white, indi-
cating that perhaps there is a population in
deeper water which never develops the color-
ation of some shallow water forms.

Genus Mirachelus Woodring, 1928

Mirachelus Woodring, 1928: 434.—McLean,
1970: 118.—McLean, 1971: 311.

Type-species.—Calliostoma corbis Dall,
1889; by original designation, Woodring,
1928: 434.

Diagnosis.—“Shell small, conical, imperfo-
rate, inner layer nacreous. Aperture sub-
quadrangular. Outer lip, as viewed from
above; slanting backward from suture. Basal
lip almost straight. Outer and basal lips lirate
within aperture. Columella vertical, bearing a
tooth-like inflation near base. Parietal wall
covered with thin wash of callus. Sculpture
reticulate.” (Woodring, 1928).

18 QUINN

Remarks.—This genus has been consid-
ered by most recent workers to be a sub-
genus of either Solariella S. V. Wood, 1842,
or Euchelus Philippi, 1847. McLean (1970)
described a species from the Eastern Pacific
whose dentition showed a close relationship
with Euchelus, but the differences in shell
sculpture and radular details indicate that
Mirachelus should be separated at the gen-
eric level. While examining material of M.
corbis in the collections of the USNM, | dis-
covered a form which seems to be specifically
distinct from corbis, and it is herein described.

Geographic distribution —Western АЕ
lantic: the southern Straits of Florida, the Gulf
of Mexico, and south to the Lesser Antilles. —
Eastern Pacific: the Galapagos Islands and
Cocos Island.

Bathymetric range.—Known from 165 to
1426 m.

Mirachelus corbis (Dall, 1889)
Figs. 35,36

Calliostoma tiara: Dall, 1881: 45 (partim).

Calliostoma corbis Dall, 1889a: 365, pl. 33,
fig. 1; 1889b: 162, pl. 33, fig. 1 (listed only;
fig. from 1889a).—Pilsbry, 1889: 381, pl.
48, fig. 7 (description and fig. from Dall,
1889a).—Johnson, 1934: 69 (listed only).

Mirachelus corbis: Woodring, 1928: 434.

Solariella (Mirachelus) corbis: Clench &
Turner, 1960: 79 (listed only).

Euchelus (Mirachelus) corbis: Keen, 1960:
1250 (listed only).—Abbott, 1974: 39, fig.
259 (listed only; fig. from Dall, 1889a).

Description.—Shell small (attaining a
height of about 5 mm), solid, compactly coni-
cal, carinate, highly sculptured, imperforate,
of about 6 whorls. Protoconch small, glassy,
of 1 whorl. Spiral sculpture of a very strong
peripheral cord and a slightly weaker sub-
sutural cord, usually with 1 or 2 similar cords
intercalated between; another cord, on which
the suture is formed, lies just under the
periphery and defines the base; base with 5
(rarely 4) cords which are slightly excavated
along their outer edges. First 1 or 2 whorls
with thin axial ribs; axial sculpture on remain-
ing whorls of strong, oblique ribs, which
nodulate the spirals and form deep, squarish
pits between the spirals; axials not as strong
on the base, but nodulate the basal spirals.
Base convex, terraced by the spiral sculpture,
imperforate. Aperture rounded, thickened
within, strongly lirate; lips thin, outer lip crenu-

lated; columella short, thickened, with a blunt
tooth in the middle.

Holotype.—MCZ 7562, from off Havana,
Cuba.

Type-locality.—Off Havana,
823 m (BLAKE sta. 517).

Material examined.—Straits of Florida:
G-56; 1, UMML 30-5519.—EOLIS sta. 329,
off Sambo Reef, 247 m; 12, USNM 450566.—
EOLIS sta. 330, off Sambo Reef, 220 m; 1,
USNM 450559.—EOLIS sta. 332, off Sambo
Reef, 210 m; 1, USNM 450560.—EOLIS sta.
333, off Key West, 201 m; 1, USNM 450534.
—EOLIS sta. 325, off Sand Key, 174m; 1,
USNM 450530.—EOLIS sta. 319, off Western
Dry Rocks, 165m; 1, USNM 450567.—
BLAKE sta. ?, off Havana, Cuba, 823 m; 1,
MCZ 7562 (photograph of holotype, courtesy
of Barbara Steger)—BLAKE sta. 20; 2,
USNM 95023.—Caribbean: ALBATROSS
sta. 2135; 1, USNM 93907.—SUI sta. 116, off
English Harbor, Antigua, “deep”; 4, USNM
500229.—SUI sta., off Barbados, “deep”; 1,
USNM 500222.

Geographic distribution.—Straits of Florida
from off Miami to Key West, the Gulf of
Mexico, and south to Barbados.

Bathymetric range.—From 165 to 1426 m.

Remarks.—This compact little species
seems to be widely distributed throughout the
Caribbean and appears to be rather rare. It is
a larger and more finely sculptured species
than M. clinocnemus n. sp., and occurs in
deeper water. It is most commonly taken in
depths of 200 to 300 m while clinocnemus is
rarely found in more than 150 m.

Cuba, in

Mirachelus clinocnemus Quinn, n. sp.
Figs. 33,34

Description.—Shell small (attaining a
height of about 4.5 mm), solid, conical, of
about 6 whorls. Protoconch small, polished,
white, of 1/2 whorls. Spiral sculpture of 2 very
strong, subequal cords, forming a square
periphery; shell constricts sharply beneath the
periphery to the base which has 4 (rarely 3 or
5) rather strong cords. Axial sculpture of
strong, retractive, widely spaced ribs; each rib
begins as a nodule at the suture and con-
tinues across the peripheral cords, forming
strong nodules; axials weak on the base, but
bead the spirals. Suture indistinct, obscured
by the subsutural nodules. Base convex,
often with an umbilical chink. Aperture subcir-
cular, thickened within by a layer of nacre; lips
thin, outer lips crenulated by the external

STRAITS OF FLORIDA TROCHIDAE 19

sculpture; columella short, straight, thickened,
with an obscure tooth in the middle, often
completely closing the umbilical chink. Oper-
culum thin, brown, corneous, multispiral.
Radular formula — 15.4.1.4.- 15. Rhachidian
with a broad base and bearing a strong cen-
tral cusp with 3 sharp lateral cusps on each
side; laterals all similar, each with a strong
central cusp and 6 lateral cusps; marginals in
two series: inner series of 5 very strong, large,
sickle-shaped teeth, inner 2 dentate on both
edges, outer 3 dentate only on outer side, all
overhanging the central part of radula; outer
series of about 10 weaker teeth directed out-
ward, outer edges of teeth may be minutely
dentate. Radula less than 0.2 mm total width
and 1.5-2.0 mm long.

VA.

FIG. 89. Partial radular row showing rhachidian,
laterals, first three marginals and one marginal from
the outer series.

Holotype.—USNM 500731, from off Peli-
can Island, Barbados.

Type-locality.—Off Pelican Island, Barba-
dos, 146 m (taken by the State University of
lowa Expedition of 1918, sta. 13).

Paratypes.—29 specimens,
711106, with same data as holotype.

Material examined.—EOLIS stations in the
Straits of Florida: 157, off Miami Bell Buoy,
40 m; 1, USNM 450514.—Off Fowey Light:
76, 73m; 1, USNM 450489.—78, 55 т; 2,
USNM 450476.—79, 64 m; 3, USNM 450487.
—90, 80 m; 1, USNM 450478.—148, 70 m; 1,
USNM 450486.—150, 64m; 3, USNM
450483.—329, off Sambo Reef, 247m; 4,
USNM 438224.—101, off Sand Key, 70 m; 1,
USNM 450528.—321, off Western Dry Rocks,
119 m; 1, USNM 450569.— BLAKE sta. 36; 2,
USNM 126796.—Antigua: SUI sta. 115, off
English Harbour, 220 m; 4, USNM 500744.—
Barbados: SUI sta. 3, off Pelican Is., 137-
146 т; 54, USNM 500723.—SUI sta. 13, off
Pelican Is., 146m; 30, USNM 500731 &
711106 (1 holotype and 29 paratypes).—SUI
sta. 18, off Pelican Is. 73m; 6, USNM
500726.—SUI sta. 21, off St. Matthais
Church, 110 m; 4, USNM 500740.—SUI sta.

USNM

25, off Pelican Is., 146 т; 2, USNM 500727.
—SUI sta. 26, off Pelican Is., 137 m; 29,
USNM 500728.—SUI sta. 27, off Pelican 15.,
146-165 m; 8, USNM 500729.—SUI sta. 29,
off Lazaretto, 165-183 m; 2, USNM 500732.
—SUI sta. 31, off Lazaretto, 146-165 m; 2,
USNM 500734.—SUI sta. 44, off Pelican Is.,
165-183 m; 7, USNM 500725.—SUI sta. 47,
off Pelican Is., 46-132 m; 8, USNM 500730.
—SUI sta. 48, off Lazaretto, 172 m; 1, USNM
500733.—SUI sta. 51, off Pelican Is., 60 m; 7,
USNM 500724.—SUI sta. 54, off Cable Sta-
tion, 60 m; 2, USNM 500735.—SUI sta. 67, off
Telegraph Station, 91-110m; 4, USNM
500736.—SUI sta. 78, off Payne’s Bay
Church, 64-137 т; 4, USNM 500739.—SUI
sta. 79, off Telegraph Station, 55-128 m; 8,
USNM 500737.—SUI sta. 80, off Telegraph
Station, 73-137 m; 8, USNM 500738.—SUI
sta., number unrecorded, 146 m; 12, USNM
500743.—SUI sta, number unrecorded,
146 т; 3, USNM 500742.—SUI sta., position
and depth unrecorded; 1, USNM 500741.—
Brazil off Chui, Rio Grande do Sul, 166 m, 17
Jan. 1972; 1, Museu Oceanogräfico do Rio
Grande No. 17. 318.

Geographic distribution —From off Miami,
south and west along the Florida Keys to off
Key West, and the Lesser Antilles to Barba-
dos; Rio Grande do Sul, Brazil.

Bathymetric range.—Known from 46 to
247 m. This species is concentrated in depths
of less than 150 m and is only occasionally
taken in greater depths. It probably does not
form a part of the molluscan fauna in the
Straits below 150 m.

Remarks.—This is the 3rd known species
in the genus Mirachelus, and the second re-
ported from the Western Atlantic. Specimens
of this species have been in the collections of
the USNM for many years as M. corbis (one
lot was labeled by Dall as corbis). M. clino-
cnemus can easily be distinguished from
corbis by the square periphery formed by two
subequal spiral cords, not one as in corbis,
the absence of spiral cords above the pe-
ripheral ones, 4 basal cords (5 in corbis), and
generally smaller size. M. clinocnemus is
generally a small, compact species, but there
are forms which have the spire somewhat ex-
tended. The umbilical chink varies from open
to completely covered by the columella.

The radula of M. clinocnemus is similar to
that illustrated by McLean (1970) for M. gala-
pagensis but has 4 lateral teeth and differently
shaped and stronger inner marginals. The
radula of M. corbis is unknown.

20 QUINN

Genus Echinogurges Quinn, gen. nov.

Margarita (partim), Auctt. (non Leach, 1814).
Solariella (partim), Auctt. (non S. V. Wood,

1842).

Calliotropis (partim), Auctt. (non Seguenza,

1903).

Type-species.—Trochus (Margarita) cla-
vatus Watson, 1879: 705; herein designated.

Gender. —Masculine.

Diagnosis.—Shell small (about 5 mm),
trochoid, acutely conical with an extended
spire, base rounded, umbilicate; shell nacre-
ous under an external chalky layer, sculptured
by spiral rows of tubercles and/or axial riblets.

Remarks.—This genus seems to be rather
well-defined, although apparently closely re-
lated to Calliotropis. At least 1 species (E.
clavatus) has been considered a juvenile of
C. aeglees (Watson). Shells of Echinogurges
can be distinguished from Calliotropis by their
much smaller size, the base rounding
smoothly into the umbilicus without an umbili-
cal keel, and their much more acutely conical
shape. To my knowledge, no living specimens
of this genus have been obtained, so radular
characters are, as yet, unavailable to aid in
placing it. Whatever its relationships, the
genus seems distinct enough to warrant
generic separation.

Geographic distribution —Amphi-Atlantic,
found in the Eastern Atlantic off Portugal, and
in the Western Atlantic off Georgia, the Straits
of Florida and the Lesser Antilles. It probably
occurs throughout the Caribbean.

Bathymetric range.—538 to 1723 m.

Echinogurges clavatus (Watson, 1879)
Figs. 43,44

Trochus (Margarita) clavatus Watson, 1879:
705; 1886: 82, pl. 5, fig. 8.

Margarita (Solariella) aegleis var. (?) clavata:
Dall, 1889a: 380; 1889b: 164 (listed only).
—Pilsbry, 1889: 318, pl. 66, figs. 98, 99
(description from Watson, 1879; figs. from
Watson, 1886).—Johnson, 1934: 71 (listed
only).

Margarita (Solariella) clavata: Dall, 1890:
332:

Solariella aegleis aegleis: Abbott, 1974: 41
(partim).

Description.—Shell small, attaining a
height of 6 mm, conical, with an extended
spire, umbilicate, of about 62 whorls, highly
nacreous when fresh. Protoconch small,
glassy, prominent, of about 12 whorls. There

are 3 sharp spiral cords on the spire and a
fourth appearing on the body whorl; each cord
is set with sharp, axially produced tubercles.
The upper spiral is just below the suture, the
second at about mid-whorl, and the third
about mid-way between the second and
fourth, on which the suture forms; the second
and third are at the periphery of the whorl.
Axial sculpture of fine, sharp riblets whose
intersections with the spirals produce the
nodulations. Base rounding smoothly into the
umbilicus with 5 or 6 beaded spiral cords.
Umbilicus deep and constricted within to a
narrow pore. Aperture almost circular; lips
thin; inner lip slightly reflected; columella
arched and rounding smoothly into the outer
lip.

Syntypes.—Syntypes are in the British
Museum (Natural History).

Type-locality.—Watson’s original descrip-
tion included 8 specimens from CHALLENG-
ER sta. 24 and 120, but he was uncertain that
the 2 from sta. 120 were the same species.
Until the type-series can be examined a final
decision cannot be made as to the type-locali-
ty, but | would expect that it should be CHAL-
LENGER sta. 24, 18°38'30"N, 64°05’30’W,
off Culebra Island, Virgin Islands, 713 m.

Material examined.—Bahamas: CI-356; 4,
UMML 30-8130.—Straits of Florida: G-23; 3,
UMML 30-8078.—G-965; 1, UMML 30-8043.
—BLAKE sta. 2; 1, USNM 94951.—ALBA-
TROSS sta. 2751; 4, USNM 95398; 3, USNM
330740.—ALBATROSS sta. 2754; 1, USNM
96877.

Geographic distribution.—The Straits of
Florida, the Bahamas, and the Lesser Antil-
les. E. clavatus probably occurs throughout
the Antillean arc.

Bathymetric range.—Taken in depths of
about 1400 to 1600 m throughout its range.

Remarks.—E. clavatus has been long re-
garded as either a form or a young specimen
of Calliotropis aeglees (Watson), C. calatha
(Dall), or C. rhina (Watson). It differs from
these species in being much smaller and
more elevated, in having the base round
smoothly into the umbilicus, and in having a
prickly aspect to the sculpture. E. clavatus
seems to be closest to E. anoxius (Dall) and
E. rhysus (Watson). E. clavatus can easily
be separated from anoxius and rhysus by
having 2 carinae at the periphery rather than
one. It is much more highly sculptured than E.
rhysus, some specimens approaching the
sculpture of anoxius, but not as coarse as in
that species.

STRAITS OF FLORIDA TROCHIDAE 21

Echinogurges anoxius (Dall, 1927)
Figs. 41,42

Solariella anoxia Dall, 1927a: 129.—Abbott,
1974: 41 (listed only).

Solariella (Machaeroplax) anoxia: Johnson,
1934: 72 (listed only).

Description.—Shell small (attaining a
height of about 4mm), acutely conical, with
an extended spire, obscurely carinate, highly
sculptured, umbilicate, of abut 572 whorls.
Protoconch small, glassy, prominent, of about
1Y2 whorls. There are 3 major angulations (1
hidden by the suture on the spire) which are
almost too obscure to be termed carinae. One
lies just below the suture, another is at mid-
whorl, and the third, on which the suture is
formed, defines the base. Fine spiral cords
may or may not be present in the intercarinal
spaces. Axial sculpture of strong, close-set
ribs which are somewhat oblique above the
periphery, from which they descend vertically
across the base and into the umbilicus. Inter-
sections of the axial and spiral sculpture result
in sharp conical tubercles. Base convex with 3
to 5 spiral cords, rounding into the umbilicus.
Umbilicus constricting within to a narrow cen-
tral pore. Aperture rounded, almost circular;
lips thin; columella arched, thin, rounding
smoothly into the outer lip.

Syntypes.—USNM 108142, from ALBA-
TROSS sta. 2668.

Type-locality.—ALBATROSS sta. 2668;
30°58’30”М, 79°38’30’W, in 538 m.

Material examined.—ALBATROSS sta.
2668; 9, USNM 108142 (syntypes).—ALBA-
TROSS sta. 2415; 1, USNM 108420; 4,
USNM 108421.—Straits of Florida: G-23; 1,
UMML 30-8097.

Geographic distribution.—Known only
from 2 stations off southern Georgia and 1 off
Miami, Florida.

Bathymetric range.—From 538 to 805 m.

Remarks.—This species looks very much
like E. clavatus (Watson) but is more strongly
sculptured and has only a single peripheral
carina rather than a double one, and is much
smaller. The spiral sculpture varies in that the
fine cords between the carinae may or may
not be present. The forms with no intermedi-
ate spirals approach the appearance of E.
rhysus (Watson), but the strong axial sculp-
ture is still present, while it is almost totally
lacking in rhysus.

Echinogurges rhysus (Watson, 1879)
Figs. 39,40

Trochus (Margarita) rhysus Watson, 1879:
706; 1886: 83, pl. 5, fig. 4.—Dall, 1889a:
380 (name only).

Margarita (Solariella) rhysus: Pilsbry, 1889:
324, pl. 66, figs. 9, 10 (description from
Watson, 1879; figs. from Watson, 1886).

Non Solariella rhyssa Dall, 1919: 360.

Description.—Shell small (attaining a
height of 4.6 mm), conical, with an extended
spire, carinate, umbilicate, of about 5%
whorls, nacreous when fresh. Protoconch
small, prominent, glassy, of about 172 whorls.
Spiral sculpture of 3 carinae set with sharp,
axially produced tubercles; only 2 of the
Carinae are visible on the spire. The upper
carina is just beneath the suture, the second
is at mid-whorl and forms the whorl periphery,
and the third, on which the suture is formed,
defines the base. Base with 4 smooth to finely
beaded cords. Axial sculpture of sharp riblets
on the first 2 whorls, becoming obsolete on
the following whorls where they are indicated
by the tubercles on the spiral sculpture. Base
convex under the sculpture, rounding into the
umbilicus, which constricts within to a narrow
central pore. Aperture subcircular; lips thin;
inner lip slightly reflected; columella concave,
thin, rounding smoothly into the outer lip.

Syntypes.—Two syntypes are in the British
Museum (Natural History).

Type-locality.—None selected. The 2
specimens representing the syntype series
were collected at 2 different CHALLENGER
stations. One was taken at station Il off Portu-
gal (38°10’N, 09°14’W) and the other was
taken off the Virgin Islands. Considering the
confusion regarding identification of species
in this genus, there is a good chance that the
2 specimens referred to E. rhysus may repre-
sent 2 different species. It is therefore neces-
sary to examine the syntypes and choose a
lectotype before a type-locality can be de-
fined.

Material examined.—ALBATROSS sta.
2415; 1, ex USNM 108421.—ALBATROSS
sta. 2654; 5, USNM 330606.—Straits of Flor-
ida: G-368; 2, UMML 30-8054.—G-1106; 1,
UMML 30-8095.—G-130; 1, UMML 30-8041.
—G-859; 1, UMML 30-8163.

Geographic distribution.—Apparently
amphi-Atlantic: reported from off Portugal
(CHALLENGER sta. Il), and known in the
Western Atlantic from off northeastern Flor-

FIGS. 39-46. 39—40. Echinogurges rhysus (Watson): G-1106, В = 4.0 тт, d = 3.1 mm. 41-42. Echino-
gurges anoxius (Dall) (syntype): ALBATROSS-2668, h = 3.8 mm, d = 2.9 mm. 43-44. Echinogurges
clavatus (Watson): G-965, h = 4.2 тт, d = 3.0 mm. 45-46. Echinogurges tubulatus (Dall) (holotype):
ALBATROSS-2668, h = 3.7 mm, d = 3.5 mm.

STRAITS OF FLORIDA TROCHIDAE 23

ida, the Straits of Florida, and off Sombrero,
Virgin Islands.

Bathymetric range.—From 805 to 1723 m.

Remarks.—E. rhysus has long been over-
looked as is evident from the short synonymy.
The last worker to mention this species in the
scientific literature seems to have been
Pilsbry in 1889, although his treatment was
merely a literature compilation, adding noth-
ing new. This species had been reported only
from off Portugal and the Virgin Islands by
Watson, so the present material represents a
substantial extension of its range.

Occasional specimens of rhysus have fine
intercalary spirals in the intercarinal spaces
and some have traces of the axial sculpture
persisting onto the last whorl, particularly be-
low the peripheral carina.

Echinogurges tubulatus (Dall, 1927)
Figs. 45,46

Solariella tubulata Dall, 1927a: 130.

Description.—Shell small, conical, cari-
nate, umbilicate, white, of about 3 whorls.
Protoconch rather large, smooth, of about 112
to 2 whorls. Spiral sculpture of 2 strong cari-
nae, forming a wide, square periphery, and a
somewhat weaker 1 defining the base. Space
between the suture and the upper carina
wide, rather flat, with fine prosocline growth
lines; between the 3 carinae there are numer-
ous strong axial cords which nodulate the
spirals. Base slightly convex, usually with 4
very faint spiral threads; umbilicus narrow,
microscopically rugose. Aperture subcircular,
slightly angulated by the spiral sculpture; lips
thin; inner lip slightly reflected; columella thin,
slightly arched.

Syntypes.—Syntype series of 2 specimens;
USNM 108109, from ALBATROSS sta. 2668

Type-locality.—ALBATROSS sta. 2668,
30°58'30"N, 79*38'30"W, in 538 m.

Material examined.—ALBATROSS sta.
2668; 2, USNM 108109 (syntypes).—ALBA-
TROSS sta. 2415; 7, USNM 108415.—Straits
of Florida: G-23; 1, UMML 30-8079.

Geographic distribution —Known only
from off southeastern Georgia and the Straits
of Florida off Miami.

Bathymetric range.—538 to 805 m.

Remarks.—This is a very well-marked
species, with its characteristic flat shoulder
and square periphery separating it immedi-
ately from any other species. It seems to fit
best in Echinogurges, but whether it really be-

longs here must await examination of soft
parts.

The specific name tubulata is evidently a
mistake for Dall's originally intended name
“tabulata,” which is a much more appropriate
name. However, only a label in the type lot
indicates this and it is impossible to determine
whether the published spelling was a typo-
graphical error or a mistake by Bartsch who
published the paper after Dall's death. Under
the rules of nomenclature, tubulatus must
stand as the specific name.

Subfamily Umboniinae Pilsbry, 1886
Genus Gaza Watson, 1879

Gaza Watson, 1879: 601; 1886: 93.
Callogaza Dall, 1881: 49 (partim).

Type-species.—Gaza daedala Watson,
1879; by monotypy.

Diagnosis.—“Shell turbinate to depressed
turbinate, rather thin, generally highly opales-
cent. Umbilicus deep, rather wide and partially
or completely covered by a columellar pad or
callus. Operculum corneous, multispiral, thin
and colored a pale amber.” (Clench & Abbott,
1943.)

Remarks.—Gaza is a beautiful and very
distinct genus of trochids. It is restricted to
deep water and possesses a thin, highly
nacreous shell which readily separates it from
other genera. lt has been considered rather
rare, but recent collections, especially in the
Gulf of Mexico and southern Caribbean, have
shown that Gaza is not uncommon, and may
even be abundant in areas of mud and sand
bottom in depths of 400-600 m. Like many
other trochids, species of Gaza probably feed
primarily on detrital material and possibly on
minute infaunal organisms, such as benthic
foraminifera.

Geographic distribution.—The few species
known seem to be distributed in deep tropical
waters, probably circumtropical, although |
can find no species attributed to the Indian
Ocean.

Bathymetric range. —Exclusively deep
water, from about 200 to over 1000 m, with
the exception of G. (Callogaza) sericata Kira
from Japan, which occurs in rather shallow
water (less than 200 m).

Subgenus Gaza Watson, 1879

Diagnosis.—Characters of the genus;
sculpture of fine spiral lirations or smooth;

24 QUINN

shell rather large, generally 20-40 mm in di-
ameter; shell of one color, usually a straw or
ivory.

Gaza (Gaza) superba cubana Clench &
Aguayo, 1940

Gaza superba cubana Clench & Aguayo,
1940: 81, pl. 15, fig. 3.

Gaza (Gaza) superba cubana: Clench &
Abbott, 1943: 3, pl. 3, figs. 1, 2.

Gaza (Gaza) superba: Abbott, 1974: 49, fig.
375a (listed as form of G. superba; figs.
from Clench & Abbott, 1943).

Description.—See Clench & Abbott, 1943.

Holotype.—MCZ 135151, from ATLANTIS
sta. 3448.

Type-locality.—ATLANTIS sta. 3448, off
Sagua la Grande, 23°21’М, 79°56’W, in
695 m.

Material examined.—Straits of Florida:
G-524; 1, UMML 30-7751.—G-917; 1, UMML
30-7677.—G-357; 1, UMML 30-6022. —
G-815; 1, UMML 30-7560.—G-130; 1, UMML
30-8135.—G-111; 1, UMML 30-8089.—S. of
Cozumel, Yucatan: P-602; 11, UMML 30-
8136.

Geographic distribution —The Northwest
Providence Channel south through the Straits
of Florida and Yucatan Channel.

Bathymetric range.—From 329 to 1089 m.

Remarks.—Clench & Abbott (1943) sug-
gested that this form is specifically distinct
from G. superba (Dall), but Abbott (1974) in-
dicated that he considered it to be an infra-
subspecific form of superba. | have not, as
yet, been able to examine enough specimens
of either species to enable me to resolve the
problem. The few specimens | have seen and
an examination of the ranges of the 2 forms
indicates to me at least a separation at the
subspecific level, and pending further re-
search, | am leaving cubana as a subspecies
of superba. G. superba differs from cubana in
being larger, more inflated, and higher-spired.
G. superba occurs throughout the Caribbean
area and extends up into the northern Gulf of
Mexico, while cubana is restricted to the
Straits of Florida and the Yucatan Channel as
far as is now known. G. superba cubana also
seems to prefer the insular margin of the
Straits, but occurs along the continental coast
of southeastern Yucatan.

Gaza (Gaza) fischeri Dall, 1889

Gaza fischeri Dall, 1889a: 355, pl. 37, fig. 6;
1889b: 160, pl. 37, fig. 6 (listed only; fig.
from 1889a).

Gaza fischeri: Pilsbry, 1889: 158, pl. 49, fig.
37 (description and fig. from Dall, 1889a).—
Johnson, 1934: 73 (listed only).—Clench &
Aguayo, 1938: 380.—Clench & Abbott,
1943: 4, pl. 3, figs. 3-5.—Abbott, 1974: 49,
fig. 376 (listed only; figs. from Clench & Ab-
bott, 1943).

Description.—See Dall, 1889a; Clench &
Abbott, 1943.

Lectotype.—Selected by Clench & Abbott
(1943), MCZ 7543, from BLAKE sta. 221.

Type-locality.—BLAKE sta. 221, off St.
Lucia, 13°54’55”М, 61%06'05"W, 772 т.

Material examined.—Straits of Florida:
G-918; 1, UMML 30-7678.—G-190; 1, UMML
30-8005.—G-226; 1, UMML 30-5711.
—G-289; 2, UMML 30-5960.—G-365; 5,
UMML 30-6024.—G-362; 4, UMML 30-6023.
—G-130; 1, UMML 30-5526.

Geographic distribution.—The Straits of
Florida and the Gulf of Mexico, and from Cuba
south throughout the Caribbean Sea.

Bathymetric range.—From 600 to 1021 m.

Remarks.—This species is readily separat-
ed from the others in the comma-like axial
plications on the early whorls and an umbilical
pad which completely covers the umbilicus.
The spiral sculpture is coarser than in Gaza
superba or G. superba cubana, and there is a
series of short radial plications around the
umbilical margin (usually hidden by the um-
bilical pad) which are not present in the other
species. G. fischeri appears to be the most
common species of Gaza in the Western At-
lantic although future trawling along the Car-
ibbean coast of Central America may show
one of the other species to be more common.

Subgenus Callogaza Dall, 1881

Callogaza Dall, 1881: 50; 1889a: 356.

—Clench & Abbott, 1943: 5.

Type-species.—Callogaza watsoni Dall,
1881; by subsequent designation, Dall,
1889a: 356.

Diagnosis.—Differs from Gaza s. s. in hav-
ing stronger spiral sculpture, a distinctly
shouldered whorl, a mottled color pattern (not

STRAITS OF FLORIDA TROCHIDAE 25

a uniform color as in Gaza), and in generally
being smaller.

Gaza (Callogaza) watsoni (Dall, 1881)

Margarita filogyra Dall, 1881: 42.

Callogaza watsoni Dall, 1881: 50.

Gaza (Callogaza) watsoni: Dall, 1889a: 356,
pl. 22, fig. 7, 7a; pl. 24, fig. 2, 2a; 1889b:
160, pl. 22, fig. 7, 7a; pl. 23, fig. 1, 1a; pl. 24,
fig. 2, 2a (listed only; figs. from 1889a).

Gaza (Callogaza) watsoni: Pilsbry, 1889:
158, pl. 49, figs. 25-28; p. 48, figs. 11, 12
(description from Dall, 1881 & 1889a; figs.
from Dall, 1889a)—Johnson, 1934: 73
(listed only).—Clench & Abbott, 1943: 5, pl.
2, figs. 3, 4.—Abbott, 1974: 49, fig. 377
(listed only; fig. from Dall, 1889a).

Gaza watsoni: Clench & Aguayo, 1938: 381.

Description.—See Dall, 1881 and 1889a;
Clench & Abbott, 1943.

Holotype.—MCZ 7544, from BLAKE sta.
12%

Type-locality.—BLAKE sta. 12, off Havana,
Cuba, 24°34'N, 83°16’W, 66 т (not 177 fms
as reported by Dall, 1881 & 1889; 117 fms, as
reported by Clench & Abbott, 1943, is a mis-
print).

Material examined.—BLAKE sta. 12; 1,
MCZ 7544.—BLAKE, sta. no. unrecorded, off
Bahia Honda, Cuba, 402 m; 2, MCZ 7546
(paratypes of Margarita filogyra).—BLAKE
sta. no. unrecorded, Yucatan Channel,
1170m; 1, MCZ 7545 (holotype of M.
filogyra); 1, MCZ 7547 (paratype of M.
filogyra).—G-897; 2, UMML 30-7725.

Geographic distribution. —G. watsoni ос-
curs around Cuba, south through the Antillean
arc, and Brazil off the Para River.

Bathymetric range.—Known from 66-
1170 m, but primarily inhabits depths greater
than 250 m.

Remarks.—G. watsoni is a very distinctive
species and cannot be confused with any of
the other known Western Atlantic species.
Margarita filogyra was described from im-
mature specimens of watsoni. Dall, acting as
first revisor in 1889, chose watsoni over
filogyra as the species name. Fortunately, no
subsequent author has attempted to revive
filogyra and the name watsoni has been ac-
cepted. Only one other species of this sub-
genus seems to be known at present, G. (C.)
sericata Kira, from Japan. However, sericata
is a relatively shallow water form, living in
100-200 m.

Subfamily Calliostomatinae Thiele, 1924
Genus Calliostoma Swainson, 1840

Calliostoma Swainson, 1840: 218, 351
Conulus Nardo, 1840: 244 (non Leske, 1778)
Ziziphinus Gray, 1840: 147 (nomen nudum);

1843: 237
Stylotrochus Seguenza,

Haeckel, 1862).
Fluxina Dall, 1881: 51.
Manotrochus Fischer, 1885: 827.
Jacinthinus Monterosato, 1889: 79.
Ampullotrochus Monterosato, 1890: 145.
Dymares Schwengel, 1942: 1.

1876: 186 (non

Type-species.—Trochus conulus Linn-
aeus, 1758; by subsequent designation:
Herrmannsen, 1846: 154.

Diagnosis.—Shell trochoid, spire conical,
base generally flattened, umbilicate or imper-
forate; interior of shell nacreous, exterior
sculptured and calcareous, with nacreous
sheen often showing through. Aperture
rounded or oblique, smooth or lirate within,
outer lip thin, base of columella thickened.
Sculpture usually of smooth or beaded spiral
cords. Operculum thin, corneous, circular,
multispiral.

Remarks.—Swainson (1840) introduced
the name Calliostoma without any designa-
tion of a type-species. His mention of Trochus
zizyphinus as an example of the genus has
been considered by some _ subsequent
authors as monotypy. However, Swainson
later in the same work (p. 351) listed 7 addi-
tional species with Trochus zizyphinus under
Calliostoma, obviously not considering it a
monotypic genus. | therefore agree with
Woodring (1928) and Olsson (1971) that this
does not constitute monotypy and that the
subsequent designation of Trochus conula
Martyn (=T. conulus Linnaeus) by Herrmann-
sen (1846) should stand.

The classification of Calliostoma has de-
pended greatly on differences in shell
morphology, especially the presence or ab-
sence of an umbilicus. This character has
been used not only at the subgeneric level,
but also to separate genera. However, Clench
& Turner (1960) discarded this approach in
favor of subgeneric groupings using jaw
morphology and radular characters, since
some species are umbilicate when young and
become imperforate with maturity. They
based their study on the jaws and radulae of
20 North Atlantic species, but since these

26 QUINN

characters have been recorded for so few
species from other geographic areas, we
must await further work along these lines to
determine whether these groupings are valid.

What little is known of the natural history of
this genus has been summarized by Clench &
Turner (1960). Most authors have considered
species of Calliostoma to be strict herbivores
or detrital feeders. Perron (1975), in a study of
3 shallow-water species of Calliostoma, es-
tablished that at least some members of the
genus are carnivorous, feeding on hydroids. It
is still probable that deep-water species are
primarily detrital feeders but may be oppor-
tunistic predators of hydroids.

Geographic distribution.—Calliostoma is
widely distributed in tropical and temperate
waters. As strictly defined it does not seem to
enter Arctic or Antarctic waters, being re-
placed in the Antarctic by closely related
genera such as Photinula Adams & Adams
and Photinastoma Powell (Powell, 1951). The
Calliostoma fauna of the western North At-
lantic is rich, probably comprised of about fifty
species.

Bathymetric range.—From the intertidal
zone to over 2000 m. The deepest Atlantic
record is 2330 т for Calliostoma suturale
(Phillipi) collected west of Morocco by the
TALISMAN. In the western North Atlantic C.
occidentale (Mighels & Adams) was taken
alive in 1792 m by the BLAKE off Georges
Bank, and several species were collected by
the BLAKE in 1472 min the Straits of Florida
off Havana, Cuba.

Subgenus Calliostoma Swainson, 1840

Type-species.—T. conulus Linnaeus,
1758, by subsequent designation; Herrmann-
sen, 1846: 154.

Diagnosis.—Shells generally imperforate,
marked with axial flames of reddish brown or
unicolored. Sculptured with beaded cords,
occasional species are found having these
cords beaded only on the early whorls. Aper-
ture subquadrate. Radula with a denticulate
central tooth, five rather uniform lateral teeth,
the first marginal tooth broad, the succeeding
marginals becoming more attenuate, and
having numerous, fine denticles. Jaw sub-
circular with their anterior ends broadly
rounded and with a short fringe.

Calliostoma (Calliostoma) pulchrum
(C. B. Adams, 1850)

Trochus pulcher C. B. Adams, 1850: 69.—
Dall, 1889a: 366.—Clench & Turner, 1950:
331. PL 40 NIET:

Calliostoma pulcher: Dall, 1889b: 162 (listed
only).—Pilsbry, 1889: 375.

Calliostoma veliei Pilsbry, 1900: 128.

Calliostoma (Calliostoma) pulchrum: Clench
& Turner, 1960: 17, pl. 3, fig. 3; pl. 14.—
Abbott, 1974: 42, fig. 306.

Description.—See Clench & Turner, 1960.
Holotype.—MCZ 156356, from Jamaica.
Type-locality. —Jamaica.

Geographic distribution.—North Carolina,
Florida, the Bahamas, Cuba, the Gulf of
Mexico and the northern Caribbean.

Bathymetric range.—This species is not
uncommon in depths of less than 2 m to about
150 m, with only 1 specimen taken in greater
depths (Pourtales, collected at an unspecified
locality in the Straits of Florida, 366 m, USNM
83382).

Remarks.—See Remarks under C. roseo-
lum. C. pulchrum seems to prefer depths of
less than 150 m, with the 1 exception of the
Pourtalès specimen. This is probably merely
a fortuitous occurrence. The specimen was
dead when collected and, because of the
precipitous nature of much of the Straits area,
the specimen might easily have been carried
to this depth by currents or perhaps a fish.

Calliostoma (Calliostoma) roseolum
Dall, 1881

Calliostoma roseolum Dall, 1881: 45; 1889b:
162, pl. 24, figs. 6, 6a (name only, figures
taken from Dall, 1889a).—Pilsbry, 1889:
373, pl. 49, figs. 35, 36 (description from
Dall, 1881; figures from Dall, 1889a).—
Johnson, 1934: 70 (name only).

Calliostoma apicinum Dall, 1881: 46; 1889b:
162, pl. 24, figs. 3, 3a (name only, figures
from Dall, 1889a).—Pilsbry, 1889: 379, pl.
60, figs. 1, 2 (description from Dall, 1881;
figures from Dall, 1889a).—Johnson, 1934:
69 (name only).

Calliostoma (Calliostoma) roseolum: Dall,
1889a: 366, pl. 24, figs. 6, 6a.—Clench 4
Turner, 1960: 19, pl. 4, fig. 3; pl. 15.—Ab-
bott, 1974: 43, fig. 307.

Calliostoma (Calliostoma) apicinum: Dall,
1889a: 366, pl. 24, figs. 3, 3a.

STRAITS OF FLORIDA TROCHIDAE 27

Description.—See Clench & Turner, 1960;
Dall, 1889a.

Holotype.—MCZ 7563, from BLAKE sta. 11.

Type-locality.—BLAKE sta. 11, 24°43’N,
83°25'W, off Havana, Cuba, 68 m.

Record.—BLAKE sta. 56 (23°09’N,
82°21'W, off Havana, Cuba, in 320 m).

Geographic distribution. —North Carolina,
both sides of Florida, west to Mexico, and
the Lesser Antilles.

Bathymetric range.—From 13 to 320 m.

Remarks.—This species can be distin-
guished from C. pulchrum by being propor-
tionally higher, more coarsely sculptured (es-
pecially on the base), and generally having
less color. Like C. pulchrum, C. roseolum is a
relatively shallow water species, occurring
commonly in depths of less than about 150 m.
The BLAKE station in the Straits (see above)
and an unspecified BLAKE station off Bar-
bados in 100 fms (183 m) are the only records
of this species from 100 fms or more. Again,
these may be no more than accidental occur-
rences since both records are near very steep
slopes down which the shells may have fallen
or been carried by currents.

Calliostoma (Calliostoma) yucatecanum
Dall, 1881

Calliostoma yucatecanum Dall, 1881: 47.

Calliostoma (Eutrochus) yucatecanum: Dall,
1889a: 370, pl. 24, figs. 4, 4a; 1889b: 162,
pl. 24, figs. 4, 4a (name only, figures from
Dall, 1889a).—Pilsbry, 1889: 407, pl. 48,
figs. 19, 20 (description from Dall, 1881;
figures from Dall, 1889a).

Calliostoma (Leiotrochus) yucatecanum:
Johnson, 1934: 70 (name only).

Calliostoma (Astele) agalma Schwengel,
1942: 1, fig. 1.

Calliostoma (Calliostoma) yucatecanum:
Clench & Turner, 1960: 27, pl. 4, fig. 4; pl. 8,
fig. 4; pl. 19.—Abbott, 1974: 43, fig. 309.

Description. —See Dall, 1889a; Clench 8
Turner, 1960.

Holotype.—MCZ 7567, BLAKE (station
number not recorded) from the Yucatan Strait
in 1170 m.

Material examined.—Off Cay Sal Bank: G-
984; 1, UMML 30-8004.—BLAKE, station
number not recorded, Yucatan Strait,
1170 m; 1, MCZ 7567 (holotype).

Geographic distribution. —North Carolina,
Florida and the Gulf of Mexico south to Yuca-
tan.

Bathymetric range.—From 9 to 1170m;
see Remarks.

Remarks.—The GERDA specimen repre-
sents an extension of the previously known
geographic range of this species. Clench &
Turner (1960) suggested that C. yucatecan-
um might be found in this general area de-
spite the absence of the species in the exten-
sive dredgings of the EOLIS. In addition to
predicting this range extension, they cast
doubt on the depth record for the holotype
(1170 m). All other records for the species fall
between 9 and 64 m and there is no record of
a BLAKE station of 1170 m in the Yucatan
Strait in the published station data for the
BLAKE (Peirce & Patterson, 1879; Smith,
1889). The GERDA specimen does not nec-
essarily confirm a deep habitat for this spe-
cies. It was dead when collected and was
taken in an area where, because of the steep
slope, the shell could easily have washed out
into deeper water after death. Consequently, |
doubt that C. yucatecanum lives in depths
much exceeding 90 m.

Calliostoma (Calliostoma) echinatum
Dall, 1881

Calliostoma echinatum Dall, 1881: 47; 1889a:
364, pl. 21, figs. 2a, 5; 1889b: 162, pl. 21,
figs. 2a, 5 (name only, figures from Dall,
1889a).—Pilsbry, 1889: 377, pl. 49, figs.
40, 41 (description from Dall, 1881; figures
from Dall, 1889a).—Johnson, 1934: 69
(name only).—Clench & Turner, 1960: 55,
pl. 36.—Abbott, 1974: 46, fig. 336.

Description.—Shell attaining 10mm in
height, conical, with extended spire, imperfo-
rate, highly sculptured, with 712 slightly con-
vex whorls. Color light tan, with faint axial flam-
mules of deep pink regularly arranged around
the periphery. Protoconch of 172 whorls,
smooth and polished, whitish. First whorl with
low axial ridges beaded by 2 spiral cords,
giving a cancellate aspect to the whorl. The
axials persist on the second whorl but disap-
pear afterward. Number of spirals increase by
intercalation from the initial 2 to 11 at the
aperture. Spirals generally alternate in size,
the body whorl having 6 major tubercled cords
with weak smooth cords in the spaces be-
tween the majors. A cord at, or just above, the
periphery is especially strong on the early
whorls, giving the spire a pagoda-like ap-
pearance, but becoming less conspicuous on
the later whorls. In addition to the major spiral
sculpture, there are microscopic incised spiral
lines on the first 3 whorls. Base slightly con-
vex, imperforate, with 13 spiral cords which
are more undulate than beaded. Aperture

28 QUINN

subquadrate, thickened in adults by a
grooved layer of nacre. Outer lip thin and
slightly crenulated by the external sculpture.
Columella white, slightly arched and twisted,
truncate anteriorly. Operculum and animal
unknown.

Holotype.—USNM cat. no. 214270, from
BLAKE sta. 62.

Type-locality.—BLAKE sta. 62, off Havana,
Cuba, 146 m.

Material examined.—Northern Straits of
Florida: G-636; 1, UMML 30-7996.—Cay Sal:
G-986, 1, UMML 30-7997.—Southern Straits
of Florida: BLAKE sta. 62, off Havana, Cuba,
146 m; 1, USNM 214270 (holotype).—Virgin
Islands; J-S: Exp. sta. 10; 18°29’20'N,
66%05'30"W, 220-293 т, 2 Feb. 1933, 9’
tangle; 1, USNM 429727.—J-S Exp. sta. 104,
18°30’40”М, 66°13’20”М/, 146-220m, 8
March 1933, oyster trawl; 1, USNM 430055.

Geographic distribution. —Off the NW
corner of the Great Bahama Bank, Cay Sal,
the northern coast of Cuba and the Virgin
Islands.

Bathymetric range.—From 87 to 293 m.

Remarks.—The 2 GERDA specimens are
only the 4th and 5th specimens collected of
this rare species. Other than the holotype are
2 specimens collected by the Johnson-
Smithsonian Expedition in 1933. All 5 records
are in the Greater Antilles, but the species
may be found in the future farther south in the
Antillean arc.

The holotype of echinatum is a young spec-
imen 5.4mm high and the GERDA speci-
mens are both mature, measuring 10mm
high. Since these are mature, | have chosen
to redescribe the species. This species is very
similar to C. roseolum Dall. With maturity
echinatum assumes the rounded periphery
and convex base of roseolum. C. echinatum
can be easily distinguished from roseolum by
its sharp, conical beading above the periph-
ery, having the cords alternating in strength,
and the smoothish basal cords. On the basis
of its extreme conchological similarity to the
group of roseolum, | am assigning echinatum
to Calliostoma (s. s.). This allocation cannot
be confirmed until the radula and jaws have
been described.

Subgenus Elmerlinia Clench
& Turner, 1960

Type-species.—Trochus jujubinus Gmelin,
1791; by original designation, Clench &
Turner, 1960: 29.

Diagnosis.—“Shell perforate in all known
species, marked with axial flames of reddish
brown or nearly unicolored. Sculpture with
beaded cords. Aperture subquadrate with the
columella arched and truncated at the base.
Radula with a central tooth having serrate or
denticulate margins, 6 lateral teeth, 4 of which
are denticulate, the 2 outer laterals plate-like
or with extremely slender cusps. First 2 mar-
ginal teeth narrow with rather large denticula-
tions; remaining marginal teeth long and finely
denticulate. Jaws long, with the anterior ends
sharply rounded and with a long fringe at the
anterior margin.” (Clench & Turner, 1960).

Calliostoma (Elmerlinia) jujubinum
(Gmelin, 1791)

Trochus jujubinus Gmelin, 1791: 3570.—
Philippi, 1847b: 37, pl. 7, figs. 8, 9; pl. 13,
fig. 5.—Fischer, 1875: 80, pl. 18, fig. 2 (non
Róding, 1798).

Trochus lunatus Röding, 1798: 82.

Trochus perspectivus ‘Koch’ Philippi, 1843:
32, pl. 1, fig. 5 (non Linnaeus, 1758; non T.
perspectivus A. Adams, 1864).

Trochus tampaensis Conrad, 1846: 26, pl. 1,
па: 35:

one jujubinus: Reeve, 1863: fig. 12.

Eutrochus alternatus Sowerby, 1874: 719, pl.
59, fig. 5.

Calliostoma (Eutrochus) jujubinum: Dall,
1889a: 369; 1889b: 162 (listed only). —
Pilsbry, 1889: 404, pl. 40, fig. 16.

Calliostoma (Eutrochus) jujubinum tampaen-
sis: Dall, 1889a: 369; 1889b: 162 (listed

only).
Calliostoma (Eutrochus) jujubinum rawsoni
Dall, 1889a: 369; 1889b: 162 (listed

only).—Pilsbry, 1889: 405.

Calliostoma (Eutrochus) jujubinum var. per-
spectivum: Pilsbry, 1889: 405, pl. 66, figs.
35,36:

Calliostoma (Leiotrochus) jujubinum jujubi-
num: Johnson, 1934: 70 (listed only).

Calliostoma (Leiotrochus) jujubinum per-
spectivum: Johnson, 1934: 70 (listed only)

Calliostoma (Leiotrochus) jujubinum rawsoni:
Johnson, 1934: 70 (listed only).

Calliostoma (Elmerlinia) jujubinum: Clench &
Turner, 1960: 31, pl. 5, fig. 2; pl. 9, fig. 1; pl.
21.—Abbott, 1974: 44, fig. 312; pl. 2, fig.
312:

Description.—See Clench & Turner, 1960.
Holotype.—The figures representing the
type of 7. jujubinus Gmelin are numbers 1612
and 1613 on Plate 167 of Chemnitz (1781).

STRAITS OF FLORIDA TROCHIDAE 29

Type-locality.—Gmelin originally gave the
locality as cited by Chemnitz: “ad insulam S.
Mauritii, et in mari Americam australem allu-
ente.” Clench & Turner (1960) restricted the
type-locality to St. Croix, Virgin Islands.

Material examined.—Northern Straits of
Florida: G-984; 1, UMML 30-8003.

Geographic distribution.—Florida, Texas
south to Colombia, and the Bahamas south
throughout the West Indies.

Bathymetric range.—From the intertidal
zone to 192 m.

Remarks.—Calliostoma jujubinum 15 an-
other shallow-water species, probably the
most common Calliostoma in the Western
Atlantic. This species evidently does not form
a part of the fauna found deeper than 180 m
as the GERDA specimen might indicate. This
specimen was taken at the same station as
reported for C. yucatecanum (off Cay Sal
Bank) and was most likely transported artifici-
ally to deep water with C. yucatecanum (see
also Remarks under C. yucatecanum). C.
jujubinum otherwise does not occur below
150 m.

Subgenus Kombologion Clench
& Turner, 1960

Type-species.—Calliostoma bairdi Verrill &
Smith, 1880; by original designation, Clench
& Turner, 1960: 37.

Diagnosis.—“Shell usually imperforate,
though generally with an umbilical depres-
sion. Sculpture consists of numerous beaded
cords which may cover the entire surface or
be formed only at the whorl periphery or
above the base. Radula with 5 to 7 nearly
uniform lateral teeth, the first and second
marginal teeth rather long and not too dissimi-
lar to the remaining marginal teeth. Outermost
marginal teeth non-serrated. Jaws rounded,
the anterior ends rather broadly rounded and
having a very short edge of fringe along the
anterior margin.” (Clench & Turner, 1960.)

Calliostoma (Kombologion) psyche
Dall, 1889

Calliostoma psyche Dall, 1878: 61 (nom.
nud.); 1880: 45 (nom. nud.).

Calliostoma (Calliostoma) bairdii psyche Dall,
1889a: 364.

Calliostoma bairdii psyche: Pilsbry, 1889:
376.

Calliostoma (Kombologion) psyche: Clench &
Turner, 1960: 39, pl. 7, fig. 1; pl. 25.

Calliostoma (Kombologion) bairdii psyche:
Abbott, 1974: 44, fig. 316.

Calliostoma subumbilicatum ‘Dall’ Abbott,
1974: 44.

Description.—See Clench & Turner, 1960.

Lectotype.—Selected by Clench & Turner
(1960) is in the MCZ, cat. no. 224572, col-
lected by Pourtales.

Type-locality.—Off the Florida Reefs in 183
to 366 m.

Material examined.—Northern Straits of
Florida: off Palm Beach, 146-165 m, Thomp-
son & McGinty coll.; 3, USNM 666964.—
EOLIS sta. 346, ESE of Fowey Rocks,
238 m; 3, USNM 438136.—EOLIS sta. 358, off
Fowey Rocks, 229m; 3, USNM 438142.—
EOLIS sta. 360, off Fowey Rocks, 183 т; 1,
USNM 438146.—EOLIS sta. 361, off Fowey
Rocks, 137-183 т; 10, USNM 438145.—
EOLIS sta. 368, off Ajax Reef, 146-183 m; 2,
USNM 438166.—G-847; 7, UMML 30-7609.
—G-606; 1, UMML 30-7416.—Southern
Straits of Florida: G-483; 2, UMML 30-7987.
—G-484; 2, UMML 30-6993.—G-432; 6,
UMML 30-7591.—G-459; 3, UMML 30-6048.
—EOLIS sta. 330, off Sambo Reef, 220 m; 2,
USNM 438173.—EOLIS sta. 331, off Sambo
Reef, 216 m; 2, USNM 438175.—EOLIS sta.
15, 8km S of Sand Key, 183 т; 2, USNM
438153.—EOLIS sta. 323, off Sand Key,
201m; 7, USNM 438158.—BLAKE, station
number unrecorded, off Sand Key, 234 m; 1,
USNM 95003.—Off Dry Tortugas, 229 m, col-
lected by J. A. Weber; 1, USNM 696741.

Geographic distribution.—From off North
Carolina south along the east coast of Florida,
the Florida Keys, and then north along the
west coast of Florida to about Tarpon Springs.

Bathymetric range.—From 26 to 443 т.
This species seems to prefer depths of about
150 to 200 m.

Remarks.—This species is extremely simi-
lar to C. bairdii Verrill & Smith. The resem-
blance is striking enough for most authors to
consider C. psyche merely a subspecies of C.
bairdii. However, Clench & Turner (1960)
separated C. psyche as a distinct species
using several characters: C. psyche is small-
er, proportionately wider, more finely sculp-
tured, with more color and an external sheen.
In addition, the radula of C. psyche has six
lateral teeth and that of C. bairdii has seven. |
have seen a specimen of what | believe to be
C. psyche from the Gulf of Mexico (in the col-
lection of Donna Black) which is larger than the
largest recorded C. bairdii, so the size may
not be of prime importance. The other differ-

30 QUINN

ences seem to be fairly constant, especially
the radular differences, and on this basis |
must agree with Clench & Turner that C.
psyche is a distinct and valid species.

C. psyche seems to prefer the lower shelf
and upper slope areas of the continental mar-
gin. There are no records of its occurrence
along the insular margin of the Straits area
(along the Bahamas or Cuba). This may be
due to the extreme steepness of the insular
margin which affords little or no horizontal
area on which to live and feed. Most deep-
water calliostomas live on mud bottoms
where presumably they feed on detritus.

Calliostoma (Kombologion) hendersoni
Dall, 1927

Calliostoma hendersoni Dall, 1927b: 7.

Calliostoma (Leiotrochus) hendersoni: John-
son, 1934: 70 (listed only).

Calliostoma (Kombologion) hendersoni:
Clench & Turner, 1960: 43, pl. 7, fig. 4; pl.
11, fig. 2; pl. 28.—Bayer, 1971; 121, fig. 4
(right).—Abbott, 1974: 44.

Description. —See Clench & Turner, 1960.

Holotype.—USNM 333703; from EOLIS
sta. 331.

Type-locality.—EOLIS sta. 331, off Sambo
Reef, Florida, 216 m.

Material examined.—Southern Straits of
Florida: G-598; 2, UMML 30-7990.—G-813;
3, UMML 30-7531.—G-482; 1, UMML
30-6987.—G-134; 1, UMML 30-5530.—
G-837; 1, UMML 30-7994.—G-866; 1, UMML
30-7618.—G-132; 3, UMML 30-7995.—
G-839; 1, UMML 30-7566.—OREGON sta.
1349 (24°03’N, 80°30’W, 274 т; 2, H. Bullis).
—EOLIS sta. 331, off Sambo Reef, 216 m; 1,
USNM 333703.

Geographic distribution.—C. hendersoni is
found only along the Florida Keys, from off
Alligator Reef (Bayer, 1971) to SE of Key
West.

Bathymetric range.—This species has а
possible depth range of 133 to 288 т, but
seems to be found most frequently near
200 m.

Remarks.—This adds 3 more records (G-
132, G-589, G-837) to those reported by
Bayer (1971), all within the established range
of the species. A specimen from off Alligator
Reef (TURSIOPS sta. 10, position not re-
corded, 133-154 т, 23 June 1966, UMML 30-
7982) increases the known size of the species
from 19.5mm (height), 23 тт (width), to
23 mm (height), 27.5 mm (width).

The umbilicus of this species is rather nar-
row and usually open, but the specimen from
G-866 has the umbilicus filled with callus,
leaving only a pit-like umbilical depression:
Abbott (1974) suggests that this is only a form
of C. psyche. However, C. hendersoni can
easily be distinguished from C. psyche by its
generally open umbilicus, smooth basal cords
and completely different radula (see Clench &
Turner, 1960: pl. 7, figs. 1 & 4). The two spe-
cies are also found in the same geographical
area (the Florida Keys) and the same depth
range (about 200 m). | must therefore con-
sider C. hendersoni a distinct species.

Calliostoma (Kombologion) schroederi
Clench & Aguayo, 1938

Calliostoma (Calliostoma) schroederi Clench
& Aguayo, 1938: 377, pl. 23, fig. 3.

Calliostoma (Kombologion) schoederi:
Clench & Turner, 1960: 45, pl. 7, fig. 2; pl.
11, fig. 1; pl. 29.—Bayer, 1971: 118, fig.
3.—Abbott, 1974: 45, fig. 329 (listed only).

Description.—See Clench & Aguayo, 1938;
Clench & Turner, 1960.

Holotype.—MCZ 135002; from ATLANTIS
sta. 2981.

Type-locality.—ATLANTIS sta. 2981,
22°48'М, 78°48'W, off Punta Alegre,
Camaguey, Cuba, 412 m.

Material examined.—Northwest Provi-
dence Channel: G-915; 1, UMML 30-7627.

Geographic distribution.—From off the NW
corner of Little Bahama Bank (Matanilla
Shoal) south through the Bahamas to the Old
Bahama Channel off Camaguey, Cuba.

Bathymetric range.—From 265 to 439 m is
the possible range, but the minimum is prob-
ably about 300 m.

Calliostoma species not assigned
to subgenera

Calliostoma sapidum Dall, 1881

Calliostoma sapidum Dall, 1881: 46; 1889b:
162, pl. 21, figs. 2, 4 (name only, figures
from 1889a).—Pilsbry, 1889: 378, pl. 49,
figs. 38, 39 (description from Dall, 1881;
figures from Dall, 1889a).—Johnson, 1934:
70 (name only).—Clench & Turner, 1960:
53, pl. 34, fig. 2.—Abbott, 1974: 46, fig. 334
(listed only).

Calliostoma (Calliostoma) sapidum: Dall,
1889a: 364, pl. 21, figs. 2, 4.

Description. —See Clench & Turner, 1960.

STRAITS OF FLORIDA TROCHIDAE 31

Holotype.—USNM 214271, from BLAKE
sta. 2.

Type-locality.—BLAKE sta. 2, 23°14’М,
82°25'W, off Havana, Cuba, 1472 m.

Material examined.—Southern Straits of
Florida: BLAKE sta. 2, 23"14'N, 82°25'W, off
Havana, Cuba, in 1472 m; 1, USNM 214271
(holotype).

Geographic distribution.—Off Tampa,
Florida, northern Cuba, Barbados and An-
tigua.

Bathymetric range.—From 121 to 1472 т.

Remarks.—This species, on conchological
grounds, seems to belong in the subgenus
Calliostoma, but until a specimen with soft
parts is found, this is mere speculation. It
seems to be closest to C. pulchrum (C. B.
Adams), but is smaller and has a stronger,
more heavily beaded peripheral cord.

Calliostoma torrei Clench &
Aguayo, 1940

Calliostoma (Calliostoma) torrei Clench &
Aguayo, 1940: 79, pl. 14, fig. 5.

Calliostoma torrei: Clench & Turner, 1960: 59,
pl. 40.—Abbott, 1974: 46 (listed only).

Description.—See Clench & Aguayo, 1940;
Clench & Turner, 1960.

Holotype.—MCZ 135165, from ATLANTIS
sta. 1985.

Type-locality—ATLANTIS sta. 1985,
2313'N, 81%22'W, off Matanzas, Cuba,
704 m.

Record and distribution.—Known only from
the holotype.

Remarks.—This appears to be the largest of
all Western Atlantic species of Calliostoma.
The holotype is 41 mm high and 36 mm wide
and only С. sayanum Dall is close to this size.

Calliostoma cubanum Clench &
Aguayo, 1940

Calliostoma (Calliostoma) cubanum Clench &
Aguayo, 1940: 78, pl. 16, fig. 4.

Calliostoma cubanum: Clench & Turner,
1960: 61, pl. 43.—Abbott, 1974: 45 (listed
only).

Description.—See Clench & Aguayo, 1940;
Clench & Turner, 1960.

Holotype.—MCZ 135163, from ATLANTIS
sta. 3474.

Type-locality.—ATLANTIS sta. 3474,
23°18’N, 80°46’W, off Cardenas, Cuba,
896 m.

Record and distribution.—Known only from
the holotype.

Remarks.—This species is known only
from a single, damaged specimen. It is,
however, a very distinctive species and can be
confused with no other.

Calliostoma atlantis Clench &
Aguayo, 1940

Calliostoma (Calliostoma) atlantis Clench &
Aguayo, 1940: 81, pl. 15, fig. 4.

Calliostoma atlantis: Clench & Turner, 1960:
62, pl. 44.

Calliostoma (Kombologion) atlantis: Abbott,
1974: 45 (listed only.)

Description.—See Clench & Aguayo, 1940;
Clench & Turner, 1960.

Holotype.—MCZ 135164, from ATLANTIS
sta. 3306.

Type-locality.—ATLANTIS sta. 3306,
2304 'N, 82°37'W, off Mariel, Pinar del Rio,
Cuba, in 603 m.

Record and distribution.—Known only from
the holotype.

Remarks.—This beautiful species is dis-
tinctive in being almost devoid of sculpture. It
most nearly resembles C. torrei Clench 8
Aguayo, C. cubanum Clench 8 Aguayo, and
C. amazonica Finlay, and bears a superficial
resemblance to C. schroederi Clench 8
Aguayo.

Calliostoma jeanneae Clench 4
Turner, 1960

Calliostoma jeanneae Clench 8 Turner, 1960:
65, pl. 47, figs. 1, 2.—Abbott, 1974: 46 (list-
ed only).

Description.—See Clench & Turner, 1960.

Holotype.—MCZ 228370, from ATLANTIS
sta., station number unrecorded, off Havana,
Cuba.

Record and distribution.—Known only from
the holotype.

Remarks.—This species is like C. atlantis
Clench 8 Aguayo in having very little sculp-
ture, but this lack of sculpture and distinctive
shape make C. jeanneae unlike any other in
the Western Atlantic.

Calliostoma sayanum Dall, 1889
Calliostoma (Eutrochus) sayanum Dall,

1889a: 370, pl. 33, figs. 10, 11; 1889b: 162,
pl. 33, figs. 10, 11 (name only, figures from

32 QUINN

Dall, 1889a).—Pilsbry, 1889: 407, pl. 60,
figs. 7, 8 (description and figures from Dall,
1889a).

Calliostoma (Leiotrochus) sayanum: John-
son, 1934: 70 (name only).

Calliostoma sayanum: Clench & Turner,
1960: 68, pl. 50, figs. 1-3.—Abbott, 1974:
45, fig. 320.

Description —See Dall, 1889a; Clench &
Turner, 1960.

Holotype.—USNM 61240,
TROSS sta. 2594.

Type-locality—ALBATROSS sta. 2594,
35°01'N, 75%12'W, SE of Cape Hatteras,
North Carolina, 293 m.

Material examined.—Northern Straits of
Florida: G-854; 1 damaged specimen, UMML
30-7610.

Remarks.—Northern Straits of Florida: off
Palm Beach in 135m, T. McGinty coll.—
Southern Straits of Florida: off Sand Key Light,
Key West, in 119m, T. McGinty coll.—
OREGON sta. 1009, 24°34’N, 83°34'W,
about 74 kilometers W of Tortugas, 366 m, H.
Bullis.

Geographic distribution —From off Cape
Hatteras, North Carolina to off the Dry
Tortugas, Florida Keys.

Bathymetric range.—From 119 to 366 m.

Remarks.—C. sayanum is a large and very
striking species. It resembles C. springeri
Clench & Turner, but it is larger, more inflated,
and has coarser sculpture and a narrower
umbilicus.

from ALBA-

Calliostoma bigelowi Clench &
Turner, 1960

Calliostoma bigelowi Clench & Turner, 1960:
72, pl. 53, figs. 1, 2.—Abbott, 1974: 46, fig.
341 (listed only).

Description.—See Clench & Turner, 1960.

Holotype.—MCZ 135003, from ATLANTIS
sta. 2963C.

Type-locality.—ATLANTIS sta. 2963C,
22°07'N, 81°08’W, off Bahia de Cochinos,
Cuba, 375 m.

Record.—Southern Straits of Florida: AT-
LANTIS sta. 2999, 23°10’N, 81°29'W, off
Matanzas, Cuba, in 265-421 m.

Geographic distribution.—The north and
south coasts of Cuba.

Calliostoma brunneum (Dall, 1881)

Fluxina brunnea Dall, 1881: 52; 1889a: 273,
pl. 22, figs. 6, 6a; 1889b; 148 pl. 22, figs. 6,
6a (name only, figures from Dall, 1889a).—

Tryon, 1887: 16 (name only).—Johnson,
1934: 101 (name only).

Calliostoma (Astele) tejedori Aguayo, 1949:
94, pl. 4, fig. 7.

Calliostoma tejedori: Clench & Turner, 1960:
13 ple 54; figs A2;

Calliostoma brunneum: Merrill, 1970a: 32.—
Abbott, 1974: 46 (listed only).

Description.—See Dall, 1881; Clench 4
Turner, 1960.

Holotype.—MCZ 7463, from BLAKE sta. 2.

Type-locality.—BLAKE sta. 2, 23°14’N,
82°25'W, off Havana, Cuba, 1472 m.

Material examined.—Northern Straits of
Florida: G-636; 1, UMML 30-7992.—Cay Sal:
G-986; 2, UMML 30-7993.—Southern Straits
of Florida: BLAKE, station number unre-
corded, off Havana, Cuba, in 146 m; 1, USNM
94897.

Record.—Arenas de la Chorrera, near
Havana, Cuba. This is a pile of construction
sand dredged from 5-27 m off Santa Fe, near
Havana.

Geographic distribution.—From the NW
corner of the Great Bahama Bank south to
Cuba, Jamaica, and Barbados.

Bathymetric range.—From 5-27 m to
1767 m.

Remarks.—C. brunneum was described by
Dall in 1881 as the only species in the genus
Fluxina. In 1889 he added a second species,
F. discula (probably a Basilissa), and placed
the genus in the Solariidae (=Architectonici-
dae). A specimen of this species was found in
a pile of construction sand near Havana, and
Aguayo (1949) correctly assigned it to Callio-
stoma, but he did not realize that his new spe-
cies, tejedori, was conspecific with F.
brunnea. The 2 species remained unques-
tioned until Merrill (1970a) examined the type
of F. brunnea while researching the Atlantic
Architectonicidae. He recognized that tejedori
was the same as brunnea and synonymized
Fluxina with Calliostoma.

This is a distinctive species, resembling in
shape С. bigelowi and С. springeri Clench 8
Turner, but has very little sculpture on the
body whorl and a brownish-red umbilicus. The
only other species in the Western Atlantic with
a colored umbilicus is C. barbouri (q.v.), but
the 2 species are completely different in shell
shape and sculpture.

Calliostoma cinctellum Dall, 1889

Calliostoma (Eutrochus) cinctellum Dall,
1889a: 372, pl. 32, figs. 1, 4; 1889b: 162, pl.

STRAITS OF FLORIDA TROCHIDAE 33

32, figs. 1, 4 (listed only; figs. from 1889a).
—Pilsbry, 1889: 409, pl. 49, figs. 31, 32
(description and figs. from Dall, 1889a).—
Clench & Turner, 1960: 80 (name only;
generic placement questioned).

Calliostoma (Leiotrochus) cinctellum: John-
son, 1934: 70 (listed only).

Basilissa cinctellum: Abbott, 1974: 38, figs.
244 (listed only; fig. from Dall, 1889a).

Description.—See Dall, 1889a.

Holotype.—USNM 214274, from BLAKE
sta. 101.

Type-locality.—BLAKE sta. 101, off Morro
Light, Havana, Cuba, in 320-457 m.

Material examined.—BLAKE sta. 101; 1,
USNM 214274 (holotype).

Geographic & bathymetric range.—Known
only from the holotype.

Remarks.—This is a very striking and beau-
tiful species. Dall, in his original remarks
(1889a), stated that cinctellum “recalls
Basilissa in its general appearance.” Clench
& Turner (1960) more directly suggested that
the species was indeed a Basilissa. Abbott
(1974) followed Clench & Turner and placed
cinctellum in his list of Basilissa species. Dall,
again in his original description, gave a care-
ful account of the jaws and radula: “Jaws
separate, squarish, composed of small horny
obliquely set rods, whose lozenge-shaped
end-sections reticulate the surface. ... The
rhachidian and (on each side) five laterals
have broad simple bases with a pear-shaped
outline; the cusps, which might be compared
to the stem of the pear bent over, are ex-
tremely narrow and long and symmetrically
serrate on each side with 4-6 serrations. The
major uncinus is stout and has a large four-
toothed ovate cusp; there are about twenty
more slender uncini with scythe-like cusps
serrate on the outer edge; outside of these
are two or three of a flat form, like a section of
a palm-leaf fan from handle to margin with
four riblets, and the distal edge with three or
more indentations. They (the uncini) are
smooth, thinner toward the distal end, and
have no distinct shaft.” This description
shows marked differences from the radula of
Basilissa alta: “rhachidian with a triangular
cusp finely denticulated on the sides, a wide
lateral with an inwardly directly triangular cusp
denticulated on both sides, and several (6 or
7) marginals, flat and rather narrow, denticu-
lated along most of the outer edge but on the
inner edge only near the tip” (Bayer, 1971:
124, fig. 7). Therefore, the radula of cinctel-
lum differs from that of Basilissa in the num-

ber and structure of both the laterals and mar-
ginals. However, the radula of cinctellum cor-
responds quite closely to that of Calliostoma
5. $. as defined and figured by Clench &
Turner (1960). Examination of the holotype of
cinctellum revealed no shell characters which
would indicate that the species belongs in
Basilissa, and on the basis of the radula, |
prefer retaining the species in Calliostoma
$. |. On conchological grounds, this species is
very similar to C. echinatum, but differs in
having a wider, more angular shell with flat
whorls and an umbilicus (see also C.
echinatum).

Calliostoma circumcinctum Dall, 1881

Calliostoma circumcinctum Dall, 1881: 44;
1889a: 364, pl. 22, figs. 3, 3a; 1889b: 162,
pl. 22, figs. 3, 3a (listed only; figs. from
1889a).—Pilsbry, 1889: 376, pl. 49, figs.
33, 34 (description from Dall, 1881; figs.
from Dall, 1889a).—Johnson, 1934: 69
(listed only).—Clench & Turner, 1960: 80
(listed only).—Abbott, 1974: 46 (listed
only.)

Description. —See Dall, 1881.

Holotype.—MCZ 7558, from BLAKE sta. 2.

Type-locality.—BLAKE sta. 2, off Havana,
Cuba, 23°14’N, 82°25’W, in 1472 т.

Material examined.—Yucatan Channel: G-
897; 1, UMML 30-7716.—BLAKE, sta. num-
ber unrecorded, 1170 m; 1, USNM 95020.

Geographic distribution.—Off Havana,
Cuba and the Yucatan Channel.

Bathymetric range.—This species has a
possible depth range of 210-1472 m, but the
2 deep records (1170 and 1472 m) were both
taken near steep escarpments. The GERDA
specimen was collected alive between 200
and 300 m, indicating that the specimens col-
lected by the BLAKE were carried to deeper
water after death.

Remarks.—This is a very distinctive spe-
cies, possessing sharp, lamellar spiral keels
which immediately separate it from any other
species of Calliostoma.

Calliostoma barbouri Clench 4
Aguayo, 1946

Calliostoma barbouri Clench & Aguayo, 1946:
89, text fig. —Clench & Turner, 1960: 67, pl.
49, figs. 1-3.—Abbott, 1974: 43, fig. 311.

Description.—See Clench & Aguayo, 1946;
Clench 4 Turner, 1960.

34 QUINN

Holotype.—MCZ 178128, from Havana,
Cuba.

Type-locality.—From Havana, Cuba, in
construction sand in Arenas de la Chorrera,
dredged in 5-27 m near Havana.

Material examined.—Straits of Florida:
G-984; 1, UMML 30-8001.—G-985; 1, UMML
30-8000.—Lesser Antilles: P-912; 1, UMML
30-8132.

Geographic distribution. —Cay Sal Bank,
northern Cuba and the Lesser Antilles.

Bathymetric range.—This species has
been taken as deep as 230 m, but the Cuban
records indicate that it is really a rather shal-
low water species.

Remarks.—C. barbouri appears to be
closely related to C. javanicum and C. jujubi-
num, and possibly С. hassler Clench 8
Aguayo. The character of barbouri which sets
it apart from all these species is the presence
of a brownish-red colored umbilicus. In this,
barbouri resembles C. brunneum, but the
shell shape of the two species is totally dissimi-
lar. On the basis of shell morphology, | suspect
that barbouri should probably be placed in the
subgenus Elmerlinia with javanicum and
jujubinum.

Genus Dentistyla Dall, 1889

Dentistyla Dall, 1889a: 373; 1889b: 162.—
Pilsbry, 1889: 411.—Johnson, 1934: 70.—
Abbott, 1974: 41.

Type-species.—Margarita asperrima Dall,
1881, by subsequent designation, Keen,
1960: 1258.

Diagnosis.—Shell rather thin, conical, base
slightly convex, usually umbilicate; exterior
sculptured by spiral rows of close-set conical
or rounded nodules, interior nacreous; aper-
ture subquadrate, somewhat oblique, some-
times thickened within; columella straight,
thickened, often with a strong tooth in mature
specimens.

Remarks.—Dentistyla was erected as a
subgenus of Calliostoma for the species
asperrima, dentifera and sericifila. Since that
time, however, the species have been vari-
ously assigned to other genera, and Denti-
styla, if used, was generally accepted at the
subgeneric level, either of Calliostoma or
Solariella. Dentistyla is a very distinctive
group, however, and the characters do not fit
any other described group, although they
most closely resemble those of Calliostoma. |
think that the peculiar nodulous sculpture and

presence of a columellar tooth are sufficient to
separate the group at the generic level, retain-
ing it within the Calliostomatinae.

Geographic distribution.—Dentistyla oc-
curs from North Carolina south through the
Straits of Florida to the extreme southern Gulf
of Mexico, and the Caribbean Sea.

Bathymetric range. —Known from 66-
914 m.

Dentistyla asperrimum (Dall, 1881)
Figs. 49,50

Margarita asperrima Dall, 1881: 40 (partim).

Calliostoma (Dentistyla) asperrimum: Dall,
1889а: 373; 1889b: 162 (listed only). —
Pilsbry, 1889: 411 (description from Dall,
1881). —Johnson, 1934: 70 (listed only). Not
Calliostoma asperrimum Guppy & Dall,
1896: 323 (=guppyi Woodring, 1928).

Calliostoma asperrimum: Woodring, 1928:
433.

Solariella (Dentistyla) asperrima: Clench &
Turner, 1960: 79.—Abbott, 1974: 41 (listed
only).

Astele (Dentistyla) asperrima: Keen, 1960:
1258.

Description.—Shell attaining a height of
8.5 mm, conical, somewhat turreted, carin-
ate, umbilicate, highly sculptured, of about 7
whorls. Protoconch small, glassy, of about 1
whorl. Spiral sculpture of 2 major nodulous
cords, of which the lower forms the peripheral
carina; between the major cords may be in-
tercalated 1 or 2 similar but weaker cords.
Below the periphery the whorl constricts
sharply to a circumbasal cord which may be
smoothish or finely beaded; base with 3 or 4
smoothish to finely beaded cords with 1
strongly beaded cord at the margin of the
umbilicus. Axial sculpture of fine threads
which are visible between the spirals, and the
intersections of spirals and axials result in the
nodulations. Base rounded; umbilicus narrow,
axially rugose, sometimes with a very fine
spiral thread near the marginal cord. Aperture
oblique, subquadrate, somewhat thickened
within; lips thin, outer lip crenulate, inner lip
slightly reflected; columella straight, thick-
ened, with a strong tooth in mature speci-
mens. Periostracum thin, brownish.

Holotype.—MCZ 7568, from BLAKE sta.
12.

Type-locality.—BLAKE sta. 12, 24°34'N,
83°16’W, in 66 m.

Material examined.—Straits of Florida:
Pourtalès Plateau, off the Florida Keys,

STRAITS OF FLORIDA TROCHIDAE 35

366 m, Nutting coll.; 2, USNM 107502.—
BLAKE sta. 12; 2, USNM 95055 (paratype).—
BLAKE sta. 20; 2, USNM 95056.—Yucatan
Channel: G-947; 1, UMML 30-7733.—
Caribbean: J-S sta. 102; 1, USNM 430365.—
P-610; 3, UMML 30-8133.

Geographic distribution.—The southern
Straits of Florida, the Yucatan Channel, and
the Antillean arc.

Bathymetric range.—Known from 66 to
914 m, but probably occurs primarily in
depths of 200 to 400 m.

Remarks.—This species is very closely re-
lated to D. dentiferum Dall and D. sericifilum
Dall. Dall himself had difficulty separating
asperrimum and dentiferum. He originally in-
cluded both forms under “Margarita” asper-
rima. In 1889 he separated dentifera as a
variety of asperrima. Only one specimen was
designated as dentifera and the others left as
asperrima. In examining the lots in the USNM,
| discovered that the specimens were, for the
most part, immature, and both species were
present in several of the lots. D. asperrimum
can be distinguished from dentiferum by its
narrower umbilicus, whose walls have at most
1 spiral thread and often none, and its coarser
sculpture. In mature shells, the nacreous
thickening within the aperture is smooth, not
lirate as in dentiferum. The Antillachelus
vaughani Woodring, 1928, seems to be D.
dentiferum, not asperrimum as suggested by
Clench and Turner (1960).

Dentistyla dentiferum (Dall, 1889)
Figs. 47,48

Calliostoma (Dentistyla) asperrimum var.
dentiferum Dall, 1889a: 373, pl. 23, figs. 7,
8; 1889b: 162, pl. 23, figs. 7, 8 (listed only;
figs. from 1889a).—Pilsbry, 1889: 411, pl.
60, figs. 10, 11 (diagnosis and figs. from
Dall, 1889a).

Basilissa (Ancistrobasis) near costulata Dall,
1903: 1585 (listed only).

Antillachelus dentiferum: Woodring, 1928:
433.

Antillachelus vaughani Woodring, 1928: 433,
pl. 36, figs. 12-14.

Euchelus (Antillachelus) dentiferus: Keen,
1960: 1250, fig. 161(6).—Abbott, 1974: 39,
41, fig. 260 (listed only).

Solariella (Dentistyla) dentifera: Clench 8
Turner, 1960: 79.

Calliostoma cf. corbis: Rice 8 Kornicker,
1965201 174 plait fig: 9:

Description.—Shell attaining a height of
8 тт, conical, carinate, umbilicate, highly
sculptured, of about 7 whorls. Protoconch
small, glassy, of about 1 whorl. Spiral sculp-
ture of 2 major beaded cords, the lower of
which forms the peripheral carina; from 1 to 3
similar cords are intercalated between, often
becoming subequal to the primaries. Below
the peripheral cord the whorl is sharply con-
stricted to a beaded circumbasal cord; base
rounded with 5 to 7 beaded cords, of which
the innermost is strongest and defines the
umbilicus. Axial sculpture of sharp riblets
whose intersections with the spirals form the
nodulations. Umbilicus moderate, axially stri-
ate, usually with one to three rather strong
nodulous spiral cords. Aperture oblique, sub-
quadrate, thickened within by nacre in which
there are numerous sharp lirations; lips thin,
outer lip somewhat crenulated, inner lip slight-
ly reflected; columella straight, oblique, usu-
ally with a strong swelling or blunt tooth.

Holotype.—USNM 95059, from BLAKE sta.

99

Type-locality.—BLAKE sta. 299, 13°05’N,
59°39'40’W, off Barbados, in 256 m.

Material examined.—ALBATROSS sta.
2602; 1, USNM 95054.—Straits of Florida: G-
1011; 1, UMML 30-7635.—EOLIS sta. 329,
off Sambo Reef, 247 m; 1, USNM 438325.—
EOLIS sta. 320, off Western Dry Rocks,
146 m; 1, USNM 450568.—BLAKE sta. 20; 2,
ex USNM 95056.—Kornicker sta. 1328,
21°50'N, 92°30'W, 168 т; 4, USNM 667860.
—Caribbean: BLAKE, sta. no. unrecorded, off
Barbados, 183 m; 1, USNM 95057.—BLAKE
sta. 299; 1, USNM 95059 (holotype); 1,
USNM 95098 (paratype).

Geographic distribution.—From off North
Carolina, south through the Straits of Florida,
the Campeche Bank, and the Lesser Antilles;
it probably occurs throughout the Caribbean.

Bathymetric range.—From 146 to 311 m.

Remarks.—(See also Remarks section
under D. asperrimum Dall.) This species is
remarkably similar to D. азреттит. D.
dentiferum can be separated from asperri-
mum by its wider umbilicus with strong spiral
sculpture within, its finer beading, more num-
erous basal cords, and especially by the
presence of sharp lirations within the aper-
ture. The external sculpture may be visible
within the apertures of juveniles of both spe-
cies as Clench & Turner observed, but in
mature specimens there are grooves cut into
the nacreous lining of dentiferum which are

36 QUINN

FIGS. 47-54. 47-48. Dentistyla dentiferum (Dall): G-1011, h = 5.9 mm, d = 5.5 mm. 49-50. Dentistyla
asperrimum (Dall): Р-610, h = 7.5 тт, d = 6.8 тт. 51-52. Solariella (Solariella) amabilis (Jeffreys) “var.
affinis” (Friele): PORCUPINE-61, h = 5.3 mm, d = 5.5 mm. 53-54. Solariella (Solariella) amabilis (Jeffreys):
“off British Isles,” h = 6.0 mm, d = 6.0 mm.

STRAITS OF FLORIDA TROCHIDAE 37

not related to the external sculpture. Speci-
mens in USNM lots 95054, 95057 and 95058
were all identified as asperrimum, but in fact
contained both species, and lot 95056 had
asperrimum, dentiferum, and the turbinid
Homalopoma linnei (Dall).

Subfamily Solariellinae Powell, 1951
Genus Solariella S. V. Wood, 1842

Margarita.—Auctt. (partim; non Leach, 1814).
Solariella S. V. Wood, 1842: 531.—Auctt.
(partim).
Machaeroplax Friele,
1878: 136.
Calliotropis.—Auctt. (partim).

1877: 311.—Sars,

Type-species.—Solariella maculata S. V.
Wood, 1842; by monotypy.

Diagnosis.—Shell small, generally less
than 10mm high, trochoid, with tubular
whorls, usually widely umbilicate, umbilicus
often bounded by a strong nodulous keel.
Sculpture of spiral cords and collabral striae,
or almost smooth. Radula short, broad, with
few (10 or less) marginals.

Remarks.—Solariella was erected by S. V.
Wood for a fossil species, S. maculata, from
the Crag Formation of England. Friele (1877)
based Machaeroplax on his M. affinis (ex
Jeffreys MS) (Figs. 51, 52). M. affinis is mere-
ly a strongly lirate variant of S. amabilis (Jef-
freys) (Figs. 53,54), and the range of charac-
ters exhibited by the varieties of S. amabilis
bridges the gap between the forms resem-
bling $. lacunella, $. iris, etc., and those of the
S. lamellosa type. | am therefore following
Thiele (1929) in regarding Machaeroplax as a
junior subjective synonym of Solariella s. $.

Solariella, since being separated from the
catch-all Margarita (=Margarites Gray,
1847), has in turn been used as a depository
of miscellaneous species. Many of the spe-
cies assigned to Solariella can be placed in
Calliotropis, Dentistyla or Microgaza.

Geographic distribution.—Worldwide, in all
oceans.

Bathymetric range.—Known from less than
50 m to well over 2000 m.

Solariella (Solariella) lacunella (Dall, 1881)
Figs. 55-58

Margarita maculata Dall, 1881: 43 (not S. V.
Wood, 1842).
Margarita lacunella Dall, 1881: 102.

Margarita (Solariella) lacunella: Dall, 1889a:
381, pl. 21, figs. 1, 1a; 1889b: 164, pl. 21,
figs. 1, 1a (listed only; figs. from 1889a).—
Pilsbry, 1889: 322, pl. 51, figs. 32, 33 (de-
scription from Dall, 1881; figs. from Dall,
1889a).

Margarita (Solariella) lacunella depressa Dall,
1889a: 382; 1889b: 164 (listed оту)—
Pilsbry, 1889: 323 (from Dall, 1889a).

Solariella (Machaeroplax) lacunella lacun-
ella: Johnson, 1934: 71 (listed only).—Ab-
bott, 1974: 40, fig. 274.

Solariella (Machaeroplax) lacunella de-
pressa: Johnson, 1934: 71 (listed only).

Description.—Shell attaining a height of
about 8.5 mm, rather thin, depressed-conical,
inflated, of about 7 whorls. Protoconch small,
glassy, of 1-1% whorls. Spiral sculpture of
numerous subequal cords (usually 15-18 on
the last whorl); inner 2 basal cords strong,
usually strongly beaded, and separated from
each other by a rather deep, narrow channel;
there are usually 5 or 6 strong, beaded cords
on the walls of the moderately wide umbilicus.
Axial sculpture of fine plications radiating from
the suture which crenulate or finely bead the
upper 2-5 spirals, otherwise visible in the
spiral interspaces as fine threads. Suture at
the bottom of a channel formed by the over-
hanging periphery and the upper spiral cord.
Aperture subcircular, thickened within by a
layer of nacre; lips thin, crenulated by the
sculpture, inner lip slightly flared. Color ivory
to yellowish-white, with a slight nacreous
sheen in some specimens, variously marked
above with splotches and flammules of straw
or reddish-brown.

Holotype.—USNM 333705, from BLAKE
sta. 2.

Type-locality.—BLAKE sta. 2, 23°14’N,
82°25'W, off Havana, Cuba, 1472 т.

Material examined.—Straits of Florida:
EOLIS sta. 310, off Government Cut, Miami,
216 т; 2, USNM 438313.—EOLIS sta. 360,
off Fowey Rocks; 183 m; 39, USNM 438386.
—EOLIS sta. 153, 5%km SE of Fowey
Rocks, depth not recorded; 64, USNM
438352.—BLAKE sta. 2; 1, USNM 333705
(holotype).—Many lots from shallower depths
in the Straits and many from the Lesser Antil-
les.

Geographic distribution —From off North
Carolina south through the Straits of Florida,
the Gulf of Mexico, and the Antillean Arc to St.
Lucia and Barbados.

Bathymetric range.—S. lacunella occurs
commonly in depths from 20 to 150 m, with

38 QUINN

FIGS. 55-60. 55-56. Solariella (Solariella) lacunella (Dall) (holotype): BLAKE-2, h = 8.7 mm, d = 8.3 mm.
57-58. Solariella (Solariella) lacunella (Dall) (“var. depressa” Dall, holotype): BLAKE-22, h = 3.7 mm, d =
4.8 mm. 59-60. Solariella (Solariella) multirestis Quinn, n. sp. (holotype): P-874, h = 11.8 mm, d =
11.5 mm.

STRAITS OF FLORIDA TROCHIDAE 39

occasional specimens known down to
1472 m, but most of the deeper records are
for dead-collected material.

Remarks.—This is primarily a shallow-
water species and does not form a major part
of the molluscan fauna below 200 m. The va-
riety described by Dall as depressa is known
only from the holotype and appears to be
merely a freak morphological variant and
should not be considered at the subspecific
rank.

Solariella (Solariella) multirestis
Quinn, n. sp.
Figs. 59,60

Description.—Shell large for the genus,
reaching 11.8 mm, spirally striate, umbilicate,
ivory-colored with axial flammules of light
brown, iridescent when fresh, of 6 tubular
whorls. Protoconch small, glassy, slightly
depressed, of about 1172 whorls. Spiral sculp-
ture above of 4 or 5 major cords with 1-3
intercalary cords between each pair; between
the suture and the upper cord is a narrow
shelf, on which there are several fine spiral
threads on the later whorls. Axial sculpture of,
on the early whorls, fine ribs which become
restricted to the subsutural shelf on later
whorls, and finally disappear on the final
whorl. Base convex, with about 6 strong, sub-
equal spiral cords and a spiral of strong beads
bounding the umbilicus; umbilicus rather
wide, very deep; walls convex with about 10
finely beaded spiral cords. Aperture subcircu-
lar, thickened within by a layer of nacre; lips
thin, simple, inner lip slightly reflected; colu-
mella smooth, arched, not thickened. Oper-
culum and radula unknown.

Holotype.—USNM 711107, from PILLS-
BURY sta. 874.

Type-locality.—P-874, 13°11.2'N, 61°05.3’W,
off St. Vincent, Lesser Antilles, 156-201 m, 6
July 1969, 5’ BLAKE trawl.

Other material—One specimen from
G-974, 24°22'N, 80°57'W, SE of Sombrero
Light, Florida Keys, 251-252 m, 3 February
1968,10' OT, UMML 30-7697; this specimen
is in poor condition but is here considered this
species.

Geographic and bathymetric distribution.—
See under Types.

Remarks.—This is one of the most striking
of the species in the $. lacunella-S. iris com-
plex.it can be distinguished readily from the
others in this group by its finer, more numer-
ous spiral cords, more numerous intraumbili-

cal cords, striking coloration, and larger size.
The 2 records of this species indicate that it
probably is widely distributed throughout the
Caribbean area, and may be present in other
collections as $. lacunella.

Solariella (Solariella) tubula Dall, 1927
Figs. 65,66

Solariella tubula Dall, 1927a: 129.—Johnson,
1934: 72 (listed only).—Abbott, 1974: 41
(listed only).

Description.—Shell small (attaining about
4 mm in height), depressed-conical, whorls
tubular and inflated, umbilicate, white, of
about 3 whorls. Protoconch small, glassy, of
about 172 whorls. Spiral sculpture varies: the
shell may be entirely smooth, it may be cov-
ered completely by spiral striations, or it may
be somewhere in between; there is usually an
umbilical keel, and the umbilicus often has a
few spirals within; there may be a sharp or
rounded subsutural ridge shouldering the
whorl. Axial sculpture, when present, consists
of numerous equal and equally spaced plica-
tions radiating from the suture, and is most
distinct on the early whorls; on specimens
with a sharp subsutural ridge, the axials finely
serrate the ridge. Umbilicus rather wide and
funicular. Aperture circular, lips thin and sim-
ple.

Syntypes.—USNM 108140, 154 speci-
mens from ALBATROSS sta. 2668.

Type-locality.—ALBATROSS sta. 2668,
30°58’30”М, 79°38’30”W, 538 m, 5 May 1886,
large beam trawl.

Material examined.—ALBATROSS sta.
2668; 154, USNM 108140 (syntypes); 5,
USNM 108134.—ALBATROSS sta. 2415; 27,
USNM 108422.—ALBATROSS sta. 2644; 1,
USNM 330533.

Geographic distribution.—Known only
from off southern Georgia and the Straits of
Florida off Miami.

Bathymetric range.—353 to 805 m.

Remarks.—This is the smallest species of
Solariella in the Straits area and probably in
the Western Atlantic. Its small size probably
accounts for its seeming rarity since it would
generally pass through the mesh of most
sampling gear other than a dredge, and if
taken might easily be overlooked in the deb-
ris. It is a rather variable species, but can be
mistaken for no other species of Solariella in
the Western Atlantic.

40 QUINN

Solariella (Solariella) lamellosa
(Verrill & Smith, 1880)
Figs. 61,62

Margarita lamellosa Verrill & Smith, 1880:
391, 397.—Verrill, 1880: 378; 1882: 530, pl.
57, fig. 38.—Watson, 1886: 82.

Margarita aegleis: Dall, 1881: 40 (partim).

Margarita (Solariella) lamellosa: Dall, 1889a:
379; 1889b: 164, pl. 63, fig. 98 (list only;
figure from Verrill, 1882).—Pilsbry, 1889:
315, pl. 57, fig. 14 (description from Verrill &
Smith, 1880; figure from Verrill, 1882).

Margarita (Solariella) amabilis: Dall, 1889a:
378 (partim); 1889b: 164 (partim; listed
only).

Solariella calatha: Dall 1927a: 128 (partim).

Solariella tiara: Dall, 1927a: 130.

Solariella lamellosa: Johnson, 1934: 71 (listed
only).

Solariella (Machaeroplax) lamellosa: Abbott,
1974: 40, fig. 275.

Description.—Shell attaining a height of
about 9 mm, thin, bluntly conical, carinate,
umbilicate, of 6 to 7 whorls. Protoconch small,
glassy, slightly depressed, of about 1 whorl.
There are 2 spiral carinae on the spire with a
3rd appearing on the body whorl; the subsutu-
ral carina bears strong, rounded tubercles
and tabulates the whorl; the 2nd carina is just
below mid-whorl, and forms the periphery; the
3rd carina, on which the suture is formed, de-
fines the base; a row of strong tubercles cir-
cumscribes the umbilicus; there may or may
not be fine spiral threads in the spaces be-
tween the carinae and within the umbilicus.
Axial sculpture of thin ribs on the first 2
whorls, becoming obsolete thereafter, re-
maining only as tubercles on the upper 2
carinae; shell otherwise with fine growth lines.
Base flattened, smooth or spirally striate; um-
bilicus wide, deep, and somewhat restricted
within. Aperture subcircular, angulated by the
carinae; lips thin and simple; columella con-
cave, not thickened.

Holotype.—USNM cat. no. 44738, from
ALBATROSS sta. 871.

Type-locality ALBATROSS sta. 871, off
Martha’s Vineyard, 210 m.

Material examined.—Straits of Florida:
G-300; 2, UMML 30-8051.—G-4; 1, UMML
30-8025.—G-830; 1, UMML 30-7565.—
ALBATROSS sta. 2644; 7, USNM 94946; 4,
USNM 330559.—G-23; 2, UMML 30-8099.—
EOLIS sta. 115, off Government Cut, 183 m;
1, USNM 438406.—EOLIS sta. off Fowey
Rocks: 153; 1, ex USNM 438352.—303; 11,

USNM 438431.—305; 4, USNM 438434.—
306; 10, USNM 438435.—340; 14, USNM
438438.—348; 2, USNM 438437.—349; 2,
USNM 438439.—360, 14, ex USNM 438349.—
361; 100, USNM 438444.—377; 12, USNM
438451.—378; 5, USNM 438456.—EOLIS
sta. 368, off Ajax Reef, 146-185 m; 5, USNM
438459.—EOLIS sta. 339, off Ragged Key,
183 m; 7, USNM 438400.—G-857; 2, UMML
30-8042.—G-834; 1, UMML 30-7538.—
G-1035; 1, UMML 30-7914.—G-970; 8, UMML
30-7770.—G-969; 1, UMML 30-8063.—
G-968; 1, UMML 30-7644.—G-967; 6, UMML
30-8062.—G-1099; 1, UMML 30-8065 —
G-861; 1, UMML 30-8058.—EOLIS sta. 302;
1, USNM 438416.—EOLIS sta. 323; 19,
USNM 438415.—Schmitt sta. 69 off Dry Tor-
tugas, 455-655m; 5, USNM 421840.—
BLAKE sta. 2; 4, USNM 94947.—BLAKE sta.
21; 4, USNM 94948.

Geographic distribution.—From off North
Carolina south through the Straits of Florida,
and the Antillean Arc to Barbados.

Bathymetric range.—Living examples of
the species have been taken from 25 to
600 m, and dead specimens are known down
to 1472 m.

Remarks.—This species has had a rather
confused history, primarily as a result of Dall's
work. At first Dall assigned specimens of S.
lamellosa and S. pourtalesi Clench & Aguayo
to Calliotropis aeglees (Watson) (Dall, 1881).
In 1889 he separated these 2 species from C.
aeglees, regarding $. lamellosa as a distinct
species. He did not consistently recognize S.
lamellosa, especially young specimens, and
placed some of these along with most of his
specimens of S. pourtalesi with the Eastern
Atlantic species S. amabilis (Jeffreys) (see
also S. pourtalesi Clench & Aguayo). Juvenile
specimens of /amellosa were also present in
lots reported by Dall (1927a) as S. calatha,
and, in the same paper, he listed a specimen
of /amellosa as S. tiara (Watson). Clench &
Aguayo (1939) finally separated S. pourtalesi
as a distinct species, but did not recognize
that some of the USNM lots of pourtalesi were
mixed, containing /amellosa as well.

S. lamellosa is very closely related to S.
amabilis and S. pourtalesi. S. lamellosa pre-
sents a neater appearance than either ama-
bilis or pourtalesi since the sculpture is
sharper and the shell is more acutely angu-
lated. The umbilicus is also wider in /amellosa
than in the other 2 species, making the base
very narrow. $. lamellosa is one of the com-
monest species in the Straits area in depths

STRAITS OF FLORIDA TROCHIDAE 41

FIGS. 61-68. 61-62. Solariella (Solariella) lamellosa (Verrill & Smith): G-967, h = 8.3 mm, d = 7.0 mm.
63-64. Solariella (Solariella) pourtalesi Clench & Aguayo: P-747, h = 9.1 тт, d = 7.6 mm. 65-66. Solariella
(Solariella) tubula (Dall) (syntype): ALBATROSS-2668, h = 3.7mm, d = 4.7mm. 67-68. Solariella
(Micropiliscus) constricta Dall (syntype): ALBATROSS-2145, h = 3.6 mm, d = 3.1 mm.

42 QUINN

greater than 200 m, but is primarily an inhabi-
tant of depths of 50 to 150 m throughout its
range.

Solariella (Solariella) pourtalesi
Clench & Aguayo, 1939
Figs. 63,64

Margarita (Solariella) amabilis: Dall, 1889a:
378 (partim); 1889b: 164 (partim; listed
only).—Pilsbry, 1889: 313 (partim) (non
Trochus amabilis Jeffreys, 1865.)

Solariella pourtalesi Clench & Aguayo, 1939:
190, pl. 28, fig. 2—Abbott, 1974: 41.

Description.—Shell large for the genus,
reaching height of 10.3 mm, rather thin, bluntly
conical, carinate, umbilicate, of about 6%
whorls. Nucleus small, inflated, glassy, of
about 112 whorls. Spiral sculpture of 2 pustu-
lose carinae, 1 just below the suture, shoul-
dering the whorl, and the other about mid-
whorl, forming the periphery; a 3rd carina, on
which the suture is formed, is thread-like,
smoothish, and circumscribes the base; fine
spiral threads may be present in the inter-
carinal spaces and on the base; a strongly
tuberculate cord borders the rather wide,
funicular umbilicus. Axial sculpture of lamellar
ribs on the second and third whorls and
prominent, irregular growth lines. Aperture
subcircular; lips thin, simple, inner lip slightly
flared over the umbilicus; columella arched,
not thickened.

Holotype.—MCZ 135108, from ATLANTIS
sta. 2993.

Type-locality— ATLANTIS sta. 2993,
23°24'N, 80°44’W, 1061 т, 15 March, 1938,
14’ Blake trawl.

Material examined.—G-693; 20, UMML 30-
8053.—G-366; 3, UMML 30-8053.—G-365; 2,
UMML 30-8052.—G-1107; 1, UMML
30-8139.—G-1106; 2, UMML 30-8046.—
G-368; 1, UMML 30-8092.—G-446; 1, UMML
30-8140.—G-375; 2, UMML 30-8056.—
G-859; 1, UMML 30-8141.—G-374; 4, UMML
30-8055.—G-128; 1, UMML 30-8142. —
G-129; 6, UMML 30-8048.—G-964; 1, UMML
30-7744; 2, UMML 30-8061.—G-965; 11,
UMML 30-7760.—G-1112; 2, UMML
30-8066.—G-960; 18, UMML 30-8060.—
G-959; 1, UMML 30-8059.—BLAKE sta. 2; 2,
USNM 94947.—Off Havana, 1873 т, Hen-
derson coll.; 1, USNM 438225.—BLAKE, sta.
no. unrecorded, Yucatan Channel, 1170 m; 3,
USNM 168774.

Geographic distribution.—From the North-
west Providence Channel south through the

Straits of Florida and the Yucatan Channel,
and southeast through the Lesser Antilles.

Bathymetric range.—This species occurs
in deep water from 275 to 2350 m.

Remarks.—This is a rather common spe-
cies in depths greater than 1000 m. In the
northern Straits the species occurs in some-
what shallower depths, about 650-1000 m,
but the record of 275-293 m (G-693) seems
suspect. The station data seem to be correct,
so perhaps the specimens were mislabeled.
Dall originally identified the species as S.
amabilis (Jeffreys) (see also $. lamellosa
(Verrill £ Smith) referring to a rather over-
drawn illustration of amabilis in Jeffrey’s work.
He also identified 1 specimen as Calliotropis
rhina (Watson). Clench & Aguayo (1939), in
working up the ATLANTIS material, finally
recognized pourtalesi as a separate species.
Even though pourtalesi is superficially rather
similar to C. rhina, it seems most closely allied
to S. lamellosa (q. v.), differing in being larger,
more coarsely sculptured, and with a relative-
ly narrow umbilicus.

Subgenus Suavotrochus Dall, 1924

Suavotrochus Dall, 1924: 90.

Type-species.—Solariella
1881; by monotypy.

Diagnosis.—Shell small, iridescent, smooth
or nearly so, umbilicate.

lubrica, Dall,

Solariella (Suavotrochus) lubrica
(Dall, 1881)
Figs. 68-74.

Margarita lubrica Dall, 1881: 44.

Margarita (Solariella) lubrica: Dall, 1889a:
392, pl. 21, figs. 9, 9a; 1889b: 164, pl. 21,
figs. 9, 9a (listed only; figs. from 1889a).—
Pilsbry, 1889: 324, pl. 51, figs. 25, 26 (de-
scription from Dall, 1881; figs. from Dall,
1889а).

Margarita (Solariella) lubrica var. таеа Dall,
1889a: 382; 1889b: 164 (listed only). —
Pilsbry, 1889: 324 (from Dall, 1889a).

Solariella (Suavotrochus) lubrica: Dall, 1924:
90.

Solariella (Machaeroplax) lubrica lubrica:
Johnson, 1934: 72 (listed only).
Solariella (Machaeroplax) lubrica
Johnson, 1934: 72 (listed only).
Solariella (Solariella) lubrica lubrica: Abbott,
1974: 41, fig. 290 (listed only; fig. from Dall,

1889a).

iridea:

STRAITS OF FLORIDA TROCHIDAE 43

Solariella (Suavotrochus) lubrica iridea: Ab-
bott, 1974: 41, fig. 290a.

Description.—Shell small (reaching a
height of 5.5 mm), bluntly conical, smooth,
brilliantly nacreous when fresh, otherwise
white, of about 5 whorls. Nucleus small,
glassy, with very fine spiral striations, of about
1-1% whorls. Whorls inflated, smooth, with a
strong subsutural ridge which breaks up into
elongate beads on the last 2 or 3 whorls; the
beads are crossed by 2 fine spiral threads,
giving the beads a squarish cross-section.
Whorl rounds smoothly into the base, at the
center of which is a moderate, funicular um-
bilicus. A ridge composed of 1 or 2 spiral
threads encircles the umbilicus in most speci-
mens; ridge beaded by strong axial plications
which originate within the umbilicus and ex-
tend a short distance onto the base. Aperture
circular; lips thin and simple; inner lip slightly
flared over the umbilicus. Operculum thin,
corneous, muitispiral.

Holotype.—USNM 95061, from BLAKE
sta. 2.

Type-locality.—BLAKE sta. 2, 23°14’М,
82°25'W, 1472 m.

Material examined.—ALBATROSS sta.
2644;1, USNM 95063; 1, USNM 95063a; 2,
USNM 330549.—EOLIS sta. off Fowey
Rocks: 346; 238 m; 1, USNM 450491.—347,
220 т; 2, USNM 438292.—348; 201 m; 2,
USNM 450490.—349, 183-274 m; 1, USNM
450493.—EOLIS sta. 372, 183 т; 1, USNM
450503.—EOLIS sta, 339, off Ragged Key,
183 m; 1, USNM 438289; 1, USNM 450554.
—G-1095; 6, UMML 30-7931.—G-1096; 5,
UMML 30-8088.—G-967; 2, UMML 30-8086.
—Schmitt sta. 69 off Tortugas, 455-655 т; 1,
USNM 421842.—BLAKE sta. 2; 1, USNM
95061 (holotype).

Geographic distribution.—From the Straits
of Florida off Miami, south throughout the
Caribbean, and the Gulf of Mexico.

Bathymetric range.—From 155 to 1472 m.
S. lubrica probably inhabits depths of about
200 to 500 m.

Remarks.—This species is somewhat vari-
able in the strength of its sculpture. Dall
(1889a) described the variety iridea from off
Cape Florida for a form which is somewhat
more inflated than the typical form, and is al-
most devoid of all sculpture. However, other
specimens from the same locality show inter-
grades which indicate that this variety is noth-
ing more than a morphological variant. The
occurrence of S. lubrica at BLAKE sta. 2
(1472 m) is probably not indicative of a nor-

mal existence at that depth. As with other
species recorded from that station, S. lubrica
probably lives in considerably shallower water
and was moved down the steep slope of the
northern Cuban coast after death.

Subgenus Micropiliscus Dall, 1927

Micropiliscus Dall, 1927a: 130.

Type-species.—Solariella (Micropiliscus)
constricta Dall, 1927; by monotypy.

Diagnosis.—Shell small, spirally striate,
umbilicate, with a large brown carinate proto-
conch.

Solariella (Micropiliscus) constricta
Dall, 1927
Figs. 67,68

Solariella (Micropiliscus) constricta Dall,
1927a: 130.

Description.—Shell small (reaching a
height of about 4 mm), turbinate, umbilicate,
of about 3 whorls. Protoconch large, conical,
brown, smooth with 1 or 2 spiral carinae just
above the suture, of about 2 whorls; there is a
sharp, flaring varix separating the protoconch
and teleoconch. Spiral sculpture of fine, weak,
subequal spiral threads over the whole sur-
face of the shell. Axial sculpture of fine growth
lines; some specimens have a series of small,
axially elongated pits radiating out from the
suture, giving the whorl a puckered aspect.
Base rounded, not set off from the rest of the
whorl; umbilicus small and pore-like, without a
carina. Aperture subcircular; lips thin and
simple.

Syntypes.—A series of 11 specimens in 2
lots is in the USNM, cat. nos. 108414a and
108414b, from ALBATROSS sta. 2415.

Type-locality.—ALBATROSS sta. 2415,
3044 'N, 79°26’W, 805 m, 1 April 1885, large
beam trawl.

Material examined.—ALBATROSS sta.
2415; 5, USNM 108414a; 6, USNM 108414b
(syntypes).—EOLIS sta. 370, off Ajax Reef,
128-165 m; 2, USNM 450572.—EOLIS sta.
344, off Key West, 183 m; 1, USNM 450536.
—EOLIS sta. 338, off Sand Key, 156 м; 1,
USNM 450526.

Geographic distribution.—This species is
known only from off southern Georgia and the
Straits of Florida off Miami and Key West.

Bathymetric range.—Known from 128-164
to 805 m.

44 QUINN

FIGS. 69-76. 69-70. Solariella (Suavotrochus) lubrica (Dall): G-1089, h = 5.5 mm, d = 4.6 mm. 71-72.

Solariella (Suavotrochus) lubrica (Dall) (var. =

5.2 mm, d = 4.8 mm. 73-74. Solariella (Suavotrochus) lubrica (Dall) (holotype): BLAKE-2, h = 4.7 mm, d =
4.0 mm. 75-76. “Solariella” tiara (Watson): G-289, h = 6.6 mm, d = 4.7 mm.

iridea” Dall, holotype): ALBATROSS-2644, h =

STRAITS OF FLORIDA TROCHIDAE 45

Remarks.—S. constricta is a very distinc-
tive species since it is the only species in the
group which has a large brown protoconch.
The shell ornamentation varies only slightly in
that the spiral striations are often slightly
stronger at the whorl periphery and the sub-
sutural pits may or may not be present.

Solariella species incertae sedis

“Solariella” tiara (Watson, 1879)
Figs. 75,76

Trochus (Ziziphinus) tiara Watson, 1879: 696;
1886: 60, pl. 6, fig. 4.

Calliostoma tiara: Dall, 1880: 45; 1881: 45
(partim); 1889a: 365; 1889b: 162 (listed
only).—Pilsbry, 1889: 380, pl. 17, fig. 29.—
Johnson, 1934: 70 (listed only).

Margarita scabriuscula Dall, 1881: 41.

Margarita (Solariella) scabriuscula: Dall,
1889a: 379, pl. 21, figs. 10, 10a; 1889b:
164, pl. 21, figs. 10, 10a (listed only; figs.
from 1889a).—Pilsbry, 1889; 330, pl. 51,
figs. 28, 29 (description from Dall, 1881;
figs. from Dall, 1889a).

Solariella scabriuscula: Johnson, 1934: 71
(listed only).—Abbott, 1974: 41, fig. 280
(listed only; fig. from Dall, 1889a).

Solariella (Machaeroplax) tiara: Johnson,
1934: 72 (listed only).

Solariella tiara: Clench & Turner, 1960: 78
(major synonymy only).—Abbott, 1974: 41
(listed only).

Description.—Shell small, thin, spire
rounded conical, of 6 to 7 whorls. Protoconch
bulbous, glassy, of 1 whorl. Spiral sculpture
of, on the spire 2, on the last whorl 3 carinae,
each set with numerous strong, conical tuber-
cles. The upper carina is separated from the
suture by a narrow flat area and is on the
same level as the suture, the second is just
below mid-whorl and forms the periphery, and
the third, on which the suture forms, defines
the base, Base with 3 to 4 spiral cords whose
sculpture ranges from weakly undulate to fair-
ly distinctly beaded; the innermost cord is
strongly beaded and bounds the umbilical
depression. Axial sculpture of sharp riblets
on the first 2 whorls persisting on later whorls
as low ridges between the carinae, irregularly
connecting tubercles on adjacent carinae.
Otherwise, there are fine, crowded, irregular
growth lines over the whole surface. Base flat-
ly rounded, with a shallow central depression,
at the center of which is a small umbilical pore
which is reduced to a chink in most speci-
mens. Aperture subrectangular, slightly thick-

ened within; lips thin, inner lip slightly reflect-
ed; columella thickened, sometimes more so
in the middle, forming an obscure tooth.
Syntypes.—Series of three specimens is in
the British Museum (Natural History), cat. nos.
87.2.9.218-220, from CHALLENGER sta. 56.
Type-locality —CHALLENGER sta. 56, off

Bermuda, 32%04'45"N, 64%59'35"W, т
1966 m.
Material examined.—G-23; 1, UMML

30-8098.—G-815; 1, UMML 30-8143.—
G-289; 1, UMML 30-8050.—G-966; 1, UMML
30-8094.—Gulf of Mexico: BLAKE sta. 44; 1,
USNM 214281 (holotype of Margarita scabri-
uscula).

Geographic distribution —Known Нот
Bermuda, the Straits of Florida, the Gulf of
Mexico, and the Caribbean, especially the
Antilles.

Bathymetric range.—This species has
been taken in depths of 400-1966 m. It
seems to be most frequent in the 600-800 m
range.

Remarks.—As can be seen in the synon-
ymy, this species has been cited frequently
since its description. However, no one has
compared specimens of tiara with the holo-
type of scabriuscula, the only known speci-
men of that species. Instead, authors sub-
sequent to Dall merely quoted from the litera-
ture. In trying to identify specimens from the
Straits, | examined the holotype of scabrius-
cula and compared it with a photograph of
one of the syntypes of tiara; | found no char-
acters on which to base a separation at the
specific level. A subsequent examination of
specimens taken by the PILLSBURY from the
Caribbean supported my belief that the two
species are in fact the same. This species has
been placed in the genus Solariella by most
authors since Dall, but in my opinion, it does
not belong there at all. | can find no described
group in which tiara fits, and so assign it to a
“genus uncertain” rank.

Genus Microgaza Dall, 1881

Microgaza Dall, 1881: 50; 1889a: 357; 1889b:
160.—Dall, in Guppy € Dall, 1896: 323.—
Pilsbry, 1889: 11, 160.—Cossmann, 1918:
258.—Woodring, 1928: 435.—Johnson,
1934: 74.— Thiele, 1929: 48.—Keen, 1960:
1262.—Abbott, 1974: 42.

Type-species.—Callogaza (Microgaza)
rotella Dall, 1881: 51; by monotypy.

Diagnosis.—Shell small, circular, de-
pressed, deeply umbilicate, highly iridescent

46 QUINN

when fresh. Aperture subquadrate, lips thin,
columella straight and simple. Sculpture of
umbilical plications extending out onto the
base and sometimes pustulations or plica-
tions at the suture. Operculum thin, cor-
neous, circular, multispiral.

Remarks.—Microgaza was introduced as a
subgenus of Callogaza Dall, 1881, for M.
rotella Dall, 1881. In 1889 he relegated
Callogaza to subgeneric rank under Gaza
Watson, 1879, and kept Microgaza as a sub-
genus, placing it in Gaza. The first usage of
Microgaza at the generic level was by Dall
(1885) in his list of eastern American mol-
luscs. Cossmann (1918) described a fossil
species from the European Miocene as
Microgaza, but Woodring (1928) expressed
doubt that it was actually in this genus. Wood-
ring in the same paper described a new sub-
species of rotella, vetula, and erected a new
subgenus to accommodate his M. coss-
manni. M. cossmanni is fossil and vetula was
first reported as a fossil, but the GERDA has
obtained 6 specimens of vetula to bring the
total number of living forms known to 3 (in-
cluding 1 subspecies).

The systematic position of Microgaza has
long been unsettled. Dall’s original placement
of Microgaza in Callogaza and then Gaza
was followed in turn by Cossmann (1918),
who included it under Eumargarita Fischer,
1885 (=Margarites Gray, 1847), Thiele (1929),
who synonymized it with So/ariella Wood,
1842, and Keen (1960), who placed it as a sub-
genus of Solariella. Examination of the radula
of Microgaza rotella rotella indicates a close
relationship with Solariella. The radular ribbon
is rather short and broad with relatively few
rows of teeth. The rhachidian is broad and
rounded posteriorly with a very strong cusp
bearing two denticles on each side. The
admedians and second laterals are similar to
each other, each with an inwardly directed
triangular cusp, denticulate only on the outer
edge. The third lateral is very strong and
broad with a rather weak, inwardly directed
cusp. The few marginals (6-8 per half-row)
are large and sickle-shaped, overhanging the
three laterals. Radular formula is 8-6.3.1.3.6-
8 (see figure below).

Microgaza rotella rotella (Dall, 1881)
Figs. 77,78

Callogaza (Microgaza) rotella Dall, 1881: 51.
Microgaza rotella: Dall, 1885: 170; 1889b:
160, pl. 22, figs. 5, 5a (listed only).—Dall, in

— e

0.1 mm
FIG. 90. Part of a half-row of the radula of Micro-

gaza rotella rotella showing the rhachidian, the
three laterals and the inner marginal.

Guppy & Dall, 1896: 323.—Woodring,
1928: 435.—Abbott, 1974: 42.

Gaza (Microgaza) rotella: Dall, 1889a: 357,
pl. 22, figs. 5, 5a.—Pilsbry, 1889: 160, pl.
48, figs. 5, 6 (description from Dall, 1881;
figs. from Dall, 1889a).—Johnson, 1934: 74
(partim; listed only). Dautzenberg, 1900:
TA

Description. —"Shell depressed, with five
whorls, somewhat flattened above and below;
nucleus small, translucent white, and with the
two first whorls smooth or marked only by
faint growth-lines; remainder of the whorls
with a narrow puckered band revolving im-
mediately below the suture, on which the shell
matter is as if it were pinched up into slight
elevations at regular intervals, about half a
millimeter apart. In some specimens, outside
of this band an impressed line revolves with
the shell; remainder smooth, shining or with
evanescent traces of revolving lines т-
pressed from within and strongest about the
rounded periphery; base rounded toward the
umbilical carina over which it seems to be
drawn into flexuously radiating well-marked
plications (about thirty-two on the last turn)
which disappear a third of the way toward the
periphery; walls of the umbilicus concave,
overhung by the carina, turns of the shell so
coiled that the part of each whorl uncovered
by its successor forms a narrow spiral plane
ascending to the apex like a spiral staircase or
screw thread. Pillar straight, thin, with no
callus; aperture rounded except at the angle
of the umbilical carina; margin thin, sharp, not
reflected or thickened; no callus on the body
whorl in the aperture; shell whitish or green-
ish; nacre less brilliant in dead or deep-water
specimens; with zigzag brown lines variously
transversely disposed and disappearing on
the base.” (Dall, 1881.)

STRAITS OF FLORIDA TROCHIDAE 47

Lectotype.—MCZ 7548, from BLAKE sta. 2.
The paralectotype from this station is MCZ
288095 and 7 more from Barbados are MCZ
7550.

Type-locality.—Here restricted, BLAKE sta.
2, 23°14'N, 82°25’W, in 1472 т.

Material examined.—Straits of Florida:
G-606; 2, UMML 30-7418.—G-451; 1, UMML
30-8009.—G-1035; 4, UMML 30-7913.—
EOLIS sta. 322, off Sand Key, 210m; 2,
USNM 437998.—EOLIS sta. 323, off Sand
Key, 201 т; 1, USNM 437999.—EOLIS sta.
344, off Key West, 183 m; 1, USNM 438004.
—EOLIS sta. 333, off Key West, 201 m; 3,
USNM 438005.—EOLIS sta. C, S. of Key
West, 183 m; 1, USNM 438007.—BLAKE sta.
2; 1 MCZ 7548 (lectotype) 1 MCZ 288095
(paralectotype).—Barbados: BLAKE sta.
number unrecorded, 183m; 7, MCZ 7550
(paralectotypes). Many lots from the EOLIS in
shallower water in the Straits, and from the
SUI expedition to Barbados.

Geographic distribution.—The southeast-
ern Gulf of Mexico, the Straits of Florida occa-
sionally as far north as Key Largo, Cuba and
south through the Antillean arc.

Bathymetric range.—The possible range is
46 to 1472 m, but most commonly occurring
in 100 to 200 m.

Remarks.—This is a beautiful species oc-
curring rather commonly in depths less than
200 m. Microgaza rotella rotella is the south-
ern form of this species, occurring occasion-
ally as far north as Key Largo. The area from
roughly Key Largo to off Miami is the transi-
tional area between the 2 subspecies, with
intermediate forms occurring commonly.
North of Miami the subspecies inornata is
found exclusively, and south of Key Largo
only true rotella is taken. This indicates that
true geographic subspecies are involved and
not mere individual or population variation.
The distinguishing character of true rotella is
the presence of a row of elongate beads just
below the suture line. The other subspecies,
inornata, lacks these pustules; however, the
name “inornata” seems never to have been
introduced validly into the literature. | herein
do so:

Microgaza rotella inornata
Quinn, n. subsp.
Figs. 74,80

Microgaza rotella: Dall, 1889a: 357 (partim);
1889b: 160 (partim); listed only).—Pilsbry,
1889: 160 (partim).

Microgaza rotella inornata Dall, in Guppy &
Dall, 1896: 323.—Woodring, 1928: 435.
Both are nomina nuda.

Microgaza rotella form inornata: Abbott,
1974: 42 (name invalid under Article 45e
(ii), International Code of Zoological No-
menclature, 1964).

Holotype.—USNM 94101,
TROSS sta. 2311.

Type-locality.—ALBATROSS sta. 2311,
32°55'N, 77°54'W, off South Carolina, in
144 m.

Description.—Shell depressed, whitish with
irregular zigzag splotches of brown on the up-
per surface of the whorls, highly iridescent, of
about 5 whorls. Nucleus small, white, pol-
ished, of 172 whorls. Post-nuclear whorls with
faint spiral lines near the periphery. A series
of radial grooves around the umbilicus crenu-
lates the umbilical keel. Occasional specimens
may have a fine smooth cord just beneath
the suture on the third and fourth whorls,
but most specimens lack this character.
Umbilicus wide, deep, with slightly concave
walls, giving the umbilicus the aspect of a
spiral ramp. Aperture subquadrate, outer lip
thin, simple; columella straight, thin, not re-
flected, forming a sharp angle with the base.

Material examined.—ALBATROSS sta.
2602; 1, USNM 94993.—ALBATROSS sta.
2592; 1, USNM 329455.—ALBATROSS sta.
2417; 1, USNM 87574. —ALBATROSS sta,
2311; 1, USNM 94101 (holotype).—ALBA-
TROSS sta. 2312; 2, USNM 93659.—ALBA-
TROSS sta. 2313; 6, USNM 94126.—ALBA-
TROSS sta. 2314; 1, USNM 322960.—Burry
coll., 24 km E of Delray Beach, 503-549 m; 1,
USNM 620314.—EOLIS sta. 189, E of Cape
Florida, 122 т; 16, USNM 438009.—EOLIS
stations off Fowey Rocks: 165, 143 m; 2,
438039.—169, 128m; 11, 438038.—174,
106 m; 3, 438037.—181, 130 m; 1, 438036.—
182, 137m; 1, 438041—183, 146m; 5,
438040.—186, 124m; 2, USNM 438016.—
305, 201 m; 1, USNM 438021.—346, 238 m;
1, USNM 438020.—351, 165m; 14, USNM
438019.—352, 165m; 13+, USNM 438018.
—353, 155m; 3, USNM 438017.—354,
146 т; 30, USNM 438022.—355, 128 т; 12,
USNM 438028.—356, 101m; 32, USNM
438027.—358, 229m; 1, USNM 438026.—
360, 183 т; 2, USNM 438025.—361, 137-
183 т; 44, USNM 438029.—362, 174 т; 20,

from ALBA-

USNM 438024.—363, 155m; 1, USNM
438023.—364, 137-165m; 24, USNM
438034.—373, 128-165 т; 27, USNM

438033.—374, 155 т; 18, USNM 438032.—

48 QUINN

FIGS. 77-82. 77-78. Microgaza rotella rotella (Dall) (lectotype): BLAKE sta. off Havana, Cuba, h = 3.8 mm,
d = 6.5 mm. 79-80. Microgaza rotella inornata Quinn, n. subsp.: G-280, h = 3.7 mm, d = 6.3 mm. 81-82.
Microgaza vetula Woodring: G-984, h = 3.8 mm, d = 6.8 mm.

STRAITS OF FLORIDA TROCHIDAE 49

375, 137-165 m; 16, USNM 438031.—382,
128 m; 3, USNM 438030.—Sta. no unrecord-
ed, 91 т; 2, USNM 438036.—EOLIS sta. off
Ragged Key: 192, 137 m; 3, USNM 438015.
—193, 146m; 12, USNM 438011.—194,
155 т; 1, USNM 438010.—339, 183 т; 2,
USNM 438014.—365, 137m; 1, USNM
438013.—366, 137-165 т; 19+, USNM
438012.—350, off Triumph Reef, 128-165 т;
49, USNM 438044.—368, off Ajax Reef, 146-
183 m; 2, USNM 438043.—369, depth unre-
corded; 2, USNM 438047.—370, off Ajax
Reef, 128-165 т; 4, USNM 438042.—376,
off Caesars Creek, 165m; 19, USNM
438046.—G-857; 1, UMML 30-8012.—
G-606; 2, UMML 30-8011.

Geographic distribution.—From Cape Hat-
teras, North Carolina, south to about Miami,
Florida.

Bathymetric range.—The possible depth
range of this form is 91 to 549 m, but the nor-
mal range is probably about 120 to 180 m.

Remarks.—See also Remarks section un-
der M. rotella rotella. The name “inornata”
has been used since 1896 when Dall first
mentioned it. This appears to be a manuscript
name for which Dall never published a diag-
nosis, description, or figure. As such the
name stands as a nomen nudum, and, since
no one has validated it since, merely listing
the name, | have corrected the oversight. |
have retained “inornata” since it is an appro-
priate name and it will serve nomenclatural
Stability best.

Microgaza vetula Woodring, 1928

Figs. 81,82
Microgaza rotella: Dall, in Guppy & Dall,
1896: 323 (partim); Dall, 1903: 1585

(partim).

Microgaza rotella var. inornata Dall, 1903:
1585 (fide Woodring, 1928; listed only).
Eumargarita (Microgaza) rotella Dall subsp.:
Cossmann, 1918: 258, pl. 9, figs. 9, 10.
Microgaza (Microgaza) rotella vetula Wood-

ring, 1928: 435, pl. 37, figs. 1-3.

Description.—Shell depressed, porcel-
laneous, white, of about 5 whorls. Nucleus
small, white, of about 1 whorl. First post-
nuclear whorl microscopically spirally striate,
2nd whorl with a series of flexuous axial rib-
lets. Sculpture on following whorls of a low
spiral cord which bears low beads and adjoins
the suture. Fine spiral threads are present on
the periphery of the whorls. Base smooth ex-
cept for a series of grooves radiating out from

the umbilicus and crenulating the umbilical
keel. Umbilicus deep, not extremely wide,
margin sharp, walls sharply angled back from
the margin, exposing part of the base of the
preceding whorl. Umbilical wall bears one to
three fine spiral threads. Aperture subquad-
rate, lips thin and simple; columella thin,
Straight, inclined, forming a sharp angle with
the basal lip.

Holotype.—USNM 369570.

Type-locality.—Bowden Formation, Jamai-
ca, Miocene.

Material examined.—Straits of Florida:
G-984; 3, UMML 30-7798.—G-985; 1, UMML
30-7815.—G-986; 2, UMML 30-7831.

Geographic distribution —Recent speci-
mens known only from the Straits of Florida
near the Cay Sal Bank; found as a fossil in the
Miocene of Jamaica (Bowden Formation).

Bathymetric range.—From 119 to 192 m.

Remarks.—This is the first record of this
species from the Recent fauna. It was evi-
dently a common species during the Miocene
of Jamaica, and was described from there as
a subspecies of M. rotella. Superficially,
vetula looks like a small bleached rotella, but
the two may be distinguished easily by
vetula's smaller size, presence of axial riblets
on the second whorl, smaller umbilicus with
its walls retreating from the margin more
sharply than in rotella, and spiral threads on
the umbilical walls of vetula. These characters
are distinctive and consistent, so | feel justi-
fied in separating vetula and rotella at the
specific level.

Genus Basilissa Watson, 1879

Basilissa Watson, 1879: 593; 1886: 96.—
Dall, 1889a: 383.—Pilsbry, 1889: 15, 419.
—Cotton, 1959: 189.—Keen, 1960: 250.—
Bayer, 1971: 123.—Abbott, 1974: 39.

Type-species.—Basilissa superba Wat-
son, 1879, by subsequent designation: Coss-
mann, 1888: 335.

Diagnosis.—Shell usually small, trochoid,
deeply umbilicate, carinate, highly nacreous.
Aperture subquadrate, lips thin; outer lip with
a wide, fairly deep sinus near the suture, and
another, narrower sinus near the periphery of
the basal lip, resulting in a claw-like projection
of the lip at the periphery. Operculum circular,
thin, concave, multispiral.

Remarks.—This genus has traditionally
been included in the Trochidae, and indeed,
species of Basilissa bear a strong resem-
blance to some members of the family, par-

50 QUINN

ticularly some of the Calliostomatinae. As
noted by Dall (1889a) and Bayer (1971) the
nacreous shells and peculiar sinuses in the
outer lip of Basilissa are quite similar to those
in Seguenzia. Bayer further stated:
“Seguenzia costulata (sic, error for S.
carinata Jeffreys) differs from Basilissa only
in having a stronger columellar fold and more
deeply sinuate lip, thus forming a transition
between the genera as already noticed by
Dall” (Bayer, 1971: 123). The radulae of
Basilissa and Seguenzia as described by
Thiele (1929) are very similar, again indicat-
ing a close relationship. Therefore, even
though | am including Basilissa in this report
on the Trochidae, | believe that it belongs in
the family Seguenziidae with Seguenzia and
Thelyssa Bayer, 1971.

Geographic distribution.—Probably cos-
mopolitan in tropical and temperate waters.

Bathymetric range.—Primarily a deep
water genus, occurring in 200-2000 m, al-
though records of B. costulata are of less than
100 m.

Subgenus Basilissa Watson, 1879

Type-species.—Basilissa superba Wat-
son, 1879, by subsequent designation: Coss-
mann, 1888: 335.

Diagnosis.—Shell thin, finely sculptured,
aperture not thickened.

Basilissa (Basilissa) alta Watson, 1879
Figs. 83,84

Basilissa alta Watson, 1879: 597; 1886: 100.
—Оа!, 1881: 48; 1889a: 384; 1889b: 164
(listed only). —Pilsbry, 1889: 419, pl. 36, fig.
5.— Johnson, 1934: 73 (listed only).—
Bayer, 1971: 123, fig. 6, D-G; fig. 7.

Seguenzia delicatula Dall, 1881: 48.

Basilissa alta var. oxytoma Watson, 1886:
100, pl. 7, fig. 8e.—Pilsbry, 1889: 421, pl.
36, fig. 4.

Basilissa alta var. delicatula: Dall, 1889a:

384, pl. 22, figs. 2, 2a; 1889b: 164 (listed
only). —Pilsbry, 1889: 421, pl. 48, figs. 3,
4.—Johnson, 1934: 73 (listed only).

Description.—See Watson, 1879 and
1886.

Holotype.—None selected. Syntypes are in
the British Museum (Natural History), nos.
87.2.9.351 and 87.2.9.352, from CHAL-

LENGER sta. 24.

Type-locality —CHALLENGER sta. 24, off
Culebra Island (Virgin Islands), 18°38’30”N,
65°05’30”W, in 713 m.

Material examined.—G-365; 1, UMML 30-
8144.—G-370; 1, UMML 30-8145.—G-478; 1,
30-8146.—G-185; 1, UMML 30-8147—
BLAKE sta. 43; 1, USNM 94941.—G-959; 5,
UMML 30-8148.—G-960; 7, UMML 30-8149.
—G-963; 1, UMML 30-7692.—G-964; 1,
UMML 30-8150; 2, UMML 30-7764.—G-965;
5, UMML 30-7759.—G-966; 1, UMML
30-8151.—G-967; 3, UMML 30-8152.—
G-1099; 1, UMML 30-8018.—G-1112; 1,
UMML 30-8022.

Geographic distribution.—Tongue of the
Ocean, Bahamas, the Straits of Florida, the
Gulf of Mexico, and south through the Antilles
to Ceara, Brazil.

Bathymetric range.—Known from 348-
1864 m, but occurs primarily in the 500-
1500 m range.

Remarks.—This species exhibits a con-
siderable variation in the strength of the sur-
face sculpture of the shell. However, since
this variation may be found in specimens of
the same population, it is preferable to con-
sider the varieties oxytoma and delicatula as
infrasubspecific forms of alta.

Basilissa (Basilissa) discula (Dall, 1889)
Figs. 87,88

Fluxina discula Dall, 1889a: 273, pl. 23, figs.
5, 6; 1889b: 148, pl. 23, figs. 5, 6 (listed
only).—Bayer, 1971: 129, fig. 8.

Planitrochus disculus: Abbott, 1974: 39 (list-
ed only).

Description.—"Shell small, whitish, pol-
ished, of about five whorls, the base of the
immersed nucleus looking exactly like a
dextral nucleus; surface marked by the fine
flexuous incremental lines, which do not inter-
rupt the polish, and by faint occasional indica-
tions of spirals; upper surface of the whorls
concave near the sutures, elsewhere flat-
tened, so that the sutural junction is slightly
elevated; periphery sharply carinated, base
moderately rounded, not impressed near the
carina; umbilicus moderate, scalar, its walls
smooth and vertical; umbilical margin cari-
nate, an impressed line just outside the
carina; aperture wide, margins thin, columella
straight, a little thickened, a wash of callus on
the body; apparently little if any notch at the
end of the umbilical carina.” (Dall, 1889a:
274).

STRAITS OF FLORIDA TROCHIDAE 51

Holotype.—USNM 508721, from BLAKE
sta. 180.

Type-locality.—BLAKE sta. 180, off Domi-
nica, 15729'18"N, 61°34’40’W, in 1796 m.

Material examined.—Bahamas: CI-356,
24°28.3'N, 77°29.5'W, 1597 m; 1, UMML 30-
8157.—Straits of Florida: G-967; 1, UMML
30-8158.—G-1106; 1, UMML 30-8019.—
G-960; 1, UMML 30-8159.—Lesser Antilles:
BLAKE 180; 1, USNM 508721 (holotype).—P-
604; 3, UMML 30-8160.

Remarks.—The considerable rarity ot this
beautiful species has no doubt led most
workers to overlook it. Merrill (1970a), in
synonymizing Fluxina with Calliostoma (see
Remarks under Callistoma brunneum), did
not even mention it, although he tentatively
assigned discula to Basilissa in his disserta-
tion (Merrill, 1970b). Bayer (1971) further dis-
cussed the similarities of the characters of
discula and those of Basilissa, but declined to
formally assign the species to Basilissa until
more material was availble for study. Abbott
(1974) placed discula in the extinct Silurian
genus Planitrochus Perner, 1903. He was in
error here since Planitrochus does not have
the distinct sinuses in the outer lip which are
evident in discula. For the present, then, | feel
that discula best fits the characters of Basi-
lissa, and until radular characters are known, |
prefer keeping discula in Basilissa.

Basilissa (Basilissa) rhyssa Dall, 1927

Basilissa (Ancistrobasis) rhyssa Dall, 1927a:
121.—Johnson, 1934: 73 (listed only).
Basilissa rhyssa: Abbott, 1974: 38 (listed

only).

Description.—Shell small, turbinate,
strongly carinate, of about 6 whorls. Nucleus
small, glassy, somewhat depressed. Whorls
of spire with a single carina or shoulder about
Уз down the whorl; body whorl periphery
formed by an extremely acute, capelike carina
which is hidden by the suture in the earlier
whorls. Axial sculpture of low, flexuous ribs
which modulate the whorl shoulder and ex-
tend down only as far as the peripheral carina.
Base slightly convex and smooth except for
very fine growth lines. Umbilicus moderate,
bounded by a spiral cord. Aperture quad-
rangular, lips thin and with the typical Basi-
lissa sinuses.

Syntypes.—Series of 3 specimens is in the
USNM, cat. no. 108145, from ALBATROSS
sta. 2668.

Type-locality ALBATROSS sta. 2668, off

Fernandina, Florida, 30°58’30”М, 79°38’
30’W, in 538 m.
Material examined.—ALBATROSS sta.

2415; 23, USNM 108395.—ALBATROSS sta.
2668; 3, USNM 108145 (syntypes).—BLAKE
За. 2; 2, USNM 214284.—BLAKE sta., Chi-
cago Academy of Sciences, position unre-
corded in the Yucatan Channel; 1, USNM
168769.

Geographic distribution.—From off south-
ern Georgia south through the Straits of Flor-
ida to the Yucatan Channel.

Bathymetric range.—Known from 538-
1472 m, but the true depth range for the spe-
cies is problematical since all records are for
dead shells. At least 1 station (BLAKE 2) had
many rather shallow-water species which had
obviously been transported down the steep
slope of the northern Cuban escarpment.

Remarks.—This is a very distinctive spe-
cies, the angulated whorls and capelike pe-
ripheral carina separating it immediately from
all other known Basilissa species. Dall (1927)
assigned rhyssa to the subgenus Ancistro-
basis Dall, 1889, but that subgenus is char-
acterized by a relatively heavy shell, with the
aperture thickened and toothed within. B.
rhyssa exhibits none of these characters and
placement in Ancistrobasis seems unwar-
ranted.

Subgenus Ancistrobasis Dall, 1889

Type-species.—Basilissa costulata Wat-
son, 1879; by monotypy.

Diagnosis.—Shell solid, slightly depressed,
highly sculptured; aperture thickened within
and provided with strong lirations forming
denticles at the aperture; columella with a
strong terminal tooth.

Basilissa (Ancistrobasis) costulata
Watson, 1879
Figs. 85,86

Basilissa costulata Watson, 1879: 600; 1886:
103, pl. 7, fig. 11.—Dall, 1881: 48.

Basilissa (Ancistrobasis) costulata: Dall,
1889а: 384; 1889b: 164 (listed only). —
Pilsbry, 1889: 426, pl. 36, fig. 3.—Johnson,
1934: 73 (listed only).—Abbott, 1974: 37
(listed only).

Basilissa (Ancistrobasis) costulata var. de-
pressa Dall, 1889a: 384, pl. 23, figs. 4, 4a;
1889b): 164, pl. 23, figs. 4, 4a (listed only;
figs. from 1889a).—Pilsbry, 1889: 428, pl.
60, figs. 14, 15 (description from Dall,

92 QUINN

FIGS. 83-88. 83-84. Basilissa (Basilissa) alta Watson: CI-356, h = 4.7 mm, d = 6.1 mm. 85-86. Basilissa
(Ancistrobasis) costulata Watson (“уаг. depressa”Dall): EOLIS-146, h = 4.2 тт, 9 = 6.1 mm. 87-88.
Basilissa (Basilissa) discula (Dall): G-967, h = 2.9mm, d = 6.6 mm.

STRAITS OF FLORIDA TROCHIDAE 53

1889a).—Johnson, 1934: 73 (listed only).—
Abbott, 1974: 37.

Description. —See Watson,
1889a.

Holotype.—None selected. Syntype series
of 3 immature specimens is in the British Mu-
seum (Natural History), cat. nos. 87.2.9.355-
357, from CHALLENGER sta. 24.

Type-locality -CHALLENGER sta. 24, off
Culebra Island, Virgin Islands, 18°38’30”N,
65°05'30"W, in 713 m.

Material examined.—Straits of Florida:
BLAKE sta. no. unrecorded, off Sand Key,
in 27 m; 1, USNM 94945.—EOLIS sta. 146,
off Key West, 179m; 3, USNM 435753.—
Yucatan Channel; BLAKE, sta. no. unrecord-
ed, 1170m; 3, USNM 94944.—G-897; 1,
UMML 30-7717.

Geographic distribution.—From off south-
ern Georgia through the Straits of Florida to
the Yucatan Channel, the northern Gulf of
Mexico, and the Virgin Islands.

Bathymetric range.—Recorded from 27-
1170 m, establishing the species as the shal-
lowest known species of the genera.

Remarks.—This is a very uncharacteristic
species of Basilissa. Its heavy shell and
strongly armed aperture, combined with its
strong, coarse sculpture, make costulata a
very easy species to recognize. There does
not seem to be enough difference between
costulata s. s. and depressa to warrant sepa-
ration.

1879; Dall,

ZOOGEOGRAPHY

Faunal affinities.—From the study of a sin-
gle family from so restricted an area as the
Straits of Florida, it is somewhat dangerous to
make broad generalizations or unqualified
comparisons with the worldwide fauna. The
results discussed herein are mostly indica-
tions, Suggestive as they might seem. How-
ever, it is of value to discuss the apparent
relationships of the Straits trochid fauna with
respect to the worldwide fauna as well as the
Western Atlantic trochids.

At the generic level, the Straits Trochidae
seem to show a strong affinity with the other
tropical areas of the world. Five genera (36%)
can be considered circumtropical, and 3 more
(21%) are cosmopolitan in tropical and tem-
perate waters. That these genera are, for the
most part, depauperate in the Western Atlan-

tic, and that there are three more genera
which are restricted to the Western Atlatnic, is
to be expected when one considers the cli-
matic changes during the late Miocene (Ek-
man, 1953). Even when the genera which
have no species occurring deeper than 180 m
(Tegula and Cittarium) are eliminated from
the analysis, the results remain virtually un-
changed.

The 54 species (including subspecies) with
maximum recorded depths of greater than
180 m fall into 5 divisions: Tropical West At-
lantic, Temperate, Northwest Atlantic, Amphi-
Atlantic and Endemic Straits. The largest of
these is the Tropical West Atlantic component
with 27 species (50%) indicating that the
Straits area is within the tropical domain of the
Western Atlantic, although at the northern
edge. As is to be expected for a marginal re-
gion, there is also a rather strong influence
from the warm temperate area to the north. In
the Straits, the Temperate Northwest At-
lantic component forms 18.5% (10 species) of
the total. These species are fairly common
from Cape Hatteras to the northern parts of
the Straits, a few species occurring as far
south as Key West, and 3 species
(Calliostoma pulchrum, C. yucatecanum, and
C. psyche) are also known from the eastern
Gulf of Mexico.

TABLE 1. List of Tropical West Atlantic Trochidae.

Calliostoma echinatum Dentistyla asperrima
Calliostoma jujubinum Microgaza rotella rotella
Calliostoma schroederi Microgaza vetula
Calliostoma sapidum Mirachelus corbis

Mirachelus clinocnemus
Gaza fischeri

Calliostoma brunneum
Calliostoma barbouri

Solariella multirestis Gaza watsoni
Solariella pourtalesi Euchelus guttarosea
Solariella lubrica Basilissa alta
Calliotropis aeglees Basilissa discula
Calliotropis calatha Basilissa costulata
Calliotropis lissocona Lischkeia imperialis

Calliotropis actinophora “Solariella” tiara

Echinogurges clavatus
nn nn

TABLE 2. List of Temperate Northwest Atlantic
Trochidae.

Calliostoma pulchrum Solariella constricta
Calliostoma yucatecanum Echinogurges anoxia
Calliostoma psyche Echinogurges tubulatus
Calliostoma sayanum Microgaza rotella inornata
Solariella tubula Basilissa rhyssa

54 QUINN

Four species (8%) may be termed Western
North Atlantic, their ranges extending from the
Carolina capes south through the Antillean
arc. Species included are Calliostoma
roseolum, Solariella lacunella, Solariella
lamellosa, and Dentistyla dentifera.

The Amphi-Atlantic and Endemic Straits
components comprise three species each
(6%). Margarites euspira, Calliotropis rhina,
and Echinogurges rhysus are known from the
eastern Atlantic as well as the West Indies.
Those species known only from the Straits of
Florida are: Calliostoma hendersoni,
Margarites Бато! and Gaza _ superba
cubana.

In examining the affinities of the shallow-
water trochids, all species whose depth
ranges fell either wholly or in part in the 0-
180 m range were included. With this restric-
tion, 26 species can be included, some of
which also occur deeper than 180 m. These
species fall into 3 groups: Tropical West At-
lantic, Temperate Northwest Atlantic and
Western North Atlantic. The shallow water
forms show a very great tropical influence
with 18 species (69%) assignable to the
Tropical West Atlantic fauna. The Temper-
ate Northwest Atlantic component contrib-
utes 4 species (15%) and the Western North
Atlantic component comprises 3 species
(12%), both significant contributions, although
not very strong when compared to the tropical
influence.

Eight species, all in the genus Calliostoma
(torrei, cubanum, atlantis, jeanneae, bige-
lowi, cinctellum, circumcinctum and orion),
were not relegated to a faunal group since all
are known only from one or two specimens
near Cuba. They may well belong in the
tropical element, so the Tropical West Atlantic
components could be as strong as 63% for
the Jeep water forms and 73% for the shallow
water species.

Ninety-five percent of the total trochid fauna
of the Straits of Florida (65 species) is re-
stricted to the Western North Atlantic, but
most of the genera are rather widespread.
This can be explained by applying the princi-
ples advanced by Ekman (1953). After the
Atlantic basin had become a substantial fea-
ture, the original Tethyan fauna of the Atlantic
was severely decimated by the late Miocene
climatic cooling. When water temperatures
once again reached tropical nature, the relict
fauna reinvaded the Wesern North Atlantic
and resulted in a unique fauna which was
isolated on the east by the still widening At-

lantic, and on the west by the Isthmus of
Panama. Species such as Solariella lacunel-
la, S. lamellosa, Margarites euspira and M.
bairdi are probably remnants of the cooler
water species which moved into the tropical
areas during the glacial periods and were
flexible enough to adapt to the elevated water
temperatures of the post-Miocene period.
From this we see a fauna that is 100%
endemic in the shallow water species and
94% endemic in the deep water species.

Bathymetric analysis.—The Straits trochid
fauna appears to fall into the bathymetric
zones proposed by Ekman (1953) with some
modification of the limits set for the bathyal
zone. The littoral, or shelf, fauna extends from
the tidal area down to about 150-180 m in the
Straits. This is somewhat shallower than the
200m boundary used by Ekman (1953),
Bruun (1957) and Voss (1967), but in the
trochid fauna at least there is a distinct break
in the species composition occurring in the
150-180 m depths. The littoral trochid fauna
of the Straits is composed of 26 species, and
is dominated by the genus Calliostoma (14
species, 54%). Fifteen species which are here
allocated to the littoral zone are also known
from deeper than 180 m, but almost all of
these records are probably fortuitous oc-
currences and only one species (Solariella
lamellosa) can be considered a true inhabit-
ant of both the littoral and bathyal zones. One
other species, Calliostoma psyche, is known
from shallow water in the northern part of its
range, but has not been taken in the littoral of
the Straits area.

The bathyal zone extends down to about
2000 m, or to about the 4°C isotherm. The
majority of the trochid species in the Straits
(39 species, 60%) are to be found in this
zone. There seems to be a slight break at
about 1000 т. This break is not a distinct
change in species composition, but rather a
rapid diminution in the number of species
found at that depth. This may be an indication
of a true faunal break as suggested by Ekman
(1953). However, it may be an artificial break
introduced by the fact that only the south-
western part of the Straits off Cuba is deeper
than 1000 m and has been less thoroughly
sampled than the shallower areas. Here,
then, | am terming the depths from 180-
1000 m the upper bathyal, and those from
1000-2000 m the lower bathyal. Only 3
species occur exclusively in the lower bathyal
of the Straits: Margarites euspira, Calliotropis
actinophora and Echinogurges clavatus.

STRAITS OF FLORIDA TROCHIDAE 55

Only 1 species (So/ariella pourtalesi) is
known from abyssal depths in the Straits, oc-

curring as deep as 2350 m.

TABLE 3. Trochidae of the Lower Bathyal Zone.

Solariella pourtalesi Gaza superba cubana
“Solariella” tiara Gaza fischeri
Margarites bairdi Gaza watsoni
Margarites euspira Basilissa alta
Echinogurges clavatus Basilissa discula
Echinogurges rhysus Basilissa rhyssa

Calliotropis actinophora

Basilissa costulata

TABLE 4. Trochidae of the Upper Bathyal Zone.

Calliostoma psyche Mirachelus corbis
Calliostoma hendersoni Calliotropis aegleis
Calliostoma schroederi Calliotropis rhina
Calliostoma sapidum Calliotropis calatha
Calliostoma sayanum Calliotropis lissocona
Solariella lamellosa Echinogurges anoxia
Solariella lubrica Echinogurges rhysus
Solariella multirestis Echinogurges tubulatus
Solariella constricta Gaza superba cubana
Solariella tubula Gaza fischeri

Gaza watsoni
Basilissa alta

Solariella pourtalesi
“Solariella” tiara

Lischkeia imperialis Basilissa costulata
Dentistyla asperrima Basilissa discula
Dentistyla dentifera Basilissa rhyssa

We see here a striking increase in the num-
ber of trochid species with increasing depth,
at least to about 1000 т. Hickman (1974)
noted this trend in a survey of the Tertiary and
Recent faunal assemblages of the Pacific
coast of North America. She also found that
the increase in the number of species resulted
in a disproportionate increase in the percent
composition of the total fauna. There are indi-
cations that this holds true in the Straits area,
but since it is very difficult to determine the
total number of prosobranch species found in
the Straits, it is impossible to quantify this
trend at present. We can get a little better idea
of the relative numbers of individuals and the
importance of the trochids in this respect.
Okutani (1968) reported that Bathybembix
aeola (Watson) was the most numerous spe-
cies in the bathyal fauna of Sagami Bay. The
collections of the GERDA indicate the same
importance of trochids in the bathyal fauna of
the Straits, at least with respect to gross num-
ber of specimens. Of the almost 1800 speci-
mens collected by the GERDA in the Straits,
342 (19%) are trochids, second in number
only to the Turridae (385 specimens, 21.5%).

TABLE 5. List of Littoral Trochidae.
Е AA TA
Calliostoma pulchrum
Calliostoma roseolum
Calliostoma yucatecanum
Calliostoma echinatum
Calliostoma jujubinum
Calliostoma brunneum
Calliostoma barbouri
Calliostoma fascinans
Calliostoma javanicum
Calliostoma adelae
Calliostoma euglyptum
Calliostoma marionae
Calliostoma orion

Calliostoma sarcodum
Solariella lucunella
Solariella lamellosa
Microgaza rotella rotella
Microgaza rotella inornata
Microgaza vetula
Mirachelus clinocnemus
Euchelus guttarosea
Lischkeia imperialis
Cittarium pica

Tegula fasciata

Tegula lividomaculata
Tegula excavata

ACKNOWLEDGMENTS

The major collection upon which this work
is based was obtained by the R/V GERDA
while engaged in the National Geographic
Society-University of Miami Deep-Sea Biol-
ogy Program under the direction of Drs. Gilbert
L. Voss and Frederick M. Bayer. This collec-
tion is deposited in the Research Collection of
the Rosenstiel School of Marine and Atmos-
pheric Sciences.

Access to specimens and type material at
the U.S. National Museum was kindly pro-
vided by Drs. Joseph Rosewater and Harald
A. Rehder; type material at the Museum of
Comparative Zoology was loaned by Dr. Ken-
neth J. Boss.

This paper was submitted to the University
of Miami in partial fulfillment of the require-
ments for the M.S. degree. To my thesis
supervisory committee | extend special
thanks. Drs. Voss and Bayer are responsible
for laying the foundation for my general and
systematic knowledge of invertebrate zool-
ogy, and afforded continuous support and
encouragement throughout my research. Dr.
Donald R. Moore was a source of much
specialized information on shelled molluscs
and Dr. Jon C. Staiger imparted a wealth of
knowledge of practical oceanography while at
sea.

| would also like to thank Mr. Robert С.
Work for sharing his invaluable knowledge of
Caribbean molluscs, and Dr. Stephen D.
Cairns for photographing some of the types
deposited at the British Museum (National
History).

56 QUINN

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MONTEROSATO, T. A. Di, 1890, Conchiglie della
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OLSSON, A. A., 1971, Mollusks from the Gulf of
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PERRON, F. E., 1975, Carnivorous Calliostoma
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PILSBRY, H. A., 1900, A new Calliostoma from
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STRAITS OF FLORIDA TROCHIDAE 59

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1-564, pl. 1-40.

60 QUINN
APPENDIX: STATION DATA
Sta. Depth

Shi no. Date Position m Gear
GERDA 4 5/4/62 25°49'N, 79°59.5'W 256 oT!
GERDA 23 6/20/62 25°32'N, 79°44'W 768 IKMT
GERDA 56 8/28/62 25°31'N, 79°20’W 458 Lyman Dredge
GERDA 126 6/20/63 24°03'N, 81°49’W 805-741 OT
GERDA 128 6/20/63 23°49'N, 81°37'W 1391-1464 10’ OT
GERDA 129 6/20/63 23°46'N, 81°15’W 1281 10’ OT
GERDA 130 6/21/63 23°59'N, 81°10’W 1021 10’ OT
GERDA 132 6/21/63 24°26'N, 80°49’W 288 10’ OT
GERDA 134 6/21/63 24730'N, 80°51'W 191 10'OT
GERDA 190 7/4/63 25°57'N, 78°07'W 732-896 OT
GERDA 226 1/23/64 24°40'N, 80°04'W 803 6’ OT
GERDA 289 4/3/64 24°11'N, 81°36 W 594-604 10’ OT
GERDA 300 4/5/64 26°16’N, 79°30’W 640 10’ OT
GERDA 35% 8/25/64 25°28'N, 79°31'W 842 6'OT
GERDA 362 9/15/64 24°11'N, 81°39’W 631 10'0T
GERDA 365 9/15/64 24°11'N, 81°37’W 672 10’ OT
GERDA 366 9/15/64 24°12'М, 81°17'W 679-709 10’ OT
GERDA 368 9/15/64 24°03’N, 81°10'W 961-1016 16’ OT
GERDA 374 9/17/64 23°50'N, 81°37'W 1208-1241 16’ OT
GERDA 375 9/17/64 23°54'N, 81°27'W 1153-1190 16’ OT
GERDA 432 11/28/64 24°19'N, 82°29’W 188-199 10’ OT
GERDA 439 11/29/64 24°14'N, 82°29'W 583-565 10’ OT
GERDA 446 11/30/64 23°57'N, 82°32'W 988-1071 10' OT
GERDA 448 12/1/64 23°54'N, 82°21'W 1135-1184 10’ OT
GERDA 449 12/1/64 23°55'N, 82°05'W 1373-1428 10'0T
GERDA 451 1/22/65 25°02’N, 80°11'W 199 10’ OT
GERDA 459 1/24/65 24°20'N, 82°52'W 187-192 10’ OT
GERDA 482 1/26/65 24°31'N, 80°51'W 205 2.5’ Scal. Ог.1
GERDA 483 1/27/65 24°30'N, 80°28’W 443 10’ OT
GERDA 484 1/27/65 24°33'N, 80°25'W 403 10’ OT
GERDA 524 3/3/65 26°17'N, 78°41'W 513-715 10’ OT
GERDA 598 4/15/65 24°47'N, 80°26’W 183 2.5’ Scal. Dr.
GERDA 606 4/15/65 25°18'N, 80°04'W 183 Brattstrom Dr.
GERDA 611 4/15/65 25°25'N, 80°05'W 119 Brattstrom Dr.
GERDA 636 6/30/65 26°04'N, 79°13’W 87 2.5’ Scal. Dr.
GERDA 693 7/21/65 26°34'N, 78°26’W 275-293 10'0T
GERDA 813 6/21/67 24°35'N, 80°37'W 201 Scallop Dr.
GERDA 815 6/22/67 24°08'N, 79°48'W 618 10’ OT
GERDA 824 7/7/67 25°37'N, 80°02’W 187-220 10’ OT
GERDA 830 7/7/67 25°40'N, 79°59'W 342 10’ OT
GERDA 834 7/10/67 25°15'N, 80°10'W 86-79 10’ OT
GERDA 837 7/11/67 24°29'N, 80°59’W 193 10’ OT
GERDA 839 7/11/67 24°23'N, 80°52'W 239 10’ OT
GERDA 847 8/2/67 25°49'N, 80°03.5'W 201-137 10’ OT
GERDA 854 8/25/67 25°27'N, 80°02'W 221 Pipe Dr.
GERDA 857 8/25/67 25°22'N, 80°03’W 194-186 10’ OT
GERDA 859 8/29/67 23°54'N, 81°57'W 1161-1200 10’ OT
GERDA 861 8/29/67 24°08'N, 81°36’W 514-558 10’ OT
GERDA 866 8/29/67 24°28'N, 81°09'W 187 10’ OT
GERDA 897 9/10/67 20°59'N, 86°24'W 293-210 10’ OT
GERDA 915 9/26/67 25°54'N, 78°12'W 439 10’ OT
GERDA 917 9/26/67 25°59'N, 78°12'W 658-704 10’ OT
GERDA 918 9/26/67 26°03'N, 78°05'W 814 10’ OT
GERDA 923 9/28/67 24°02’N, 77°34'W 1554-1573 10’ OT
GERDA 947 1/27/68 21°13’N, 86°25’W 284-247 Triangular Dr.
GERDA 959 1/31/68 23°25'N, 82°35'W 1830 10’ OT
GERDA 960 1/31/68 23°30'N, 82°26’W 1692-1697 10’ OT
GERDA 963 2/1/68 23°41'N,82°16'W 1441-1454 10’ OT

STRAITS OF FLORIDA TROCHIDAE

APPENDIX (continued)

61

Shi

GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA
GERDA

PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY
PILLSBURY

COLUMBUS
ISELIN

BLAKE
BLAKE
BLAKE

Date

2/1/68
2/1/68
2/2/68
2/2/68
2/2/68
2/2/68
2/2/68
2/3/68
3/5/68
3/5/68
3/5/68
6/14/68
6/14/68
6/15/68
6/15/68
2/26/69
4/28/69
4/28/69
4/28/69
4/29/69
4/29/69
4/30/69
4/30/69
3/31/71

7/18/66
5/23/67
3/15/68
3/17/68
3/17/68
3/17/68
3/17/68
3/18/68
7/24/68
7/26/68
7/29/68
7/2/69

7/4/69

7/6/69

7/9/69

7/9/69

7/9/69

7/12/69
7/15/69
7/23/69
7/6/70

7/14/70
7/14/70
7/15/70
7/15/70
12/5/70

Position

23°46’N, 81°51'W
23°45'N, 81°49'W
24°10'N, 82°22'W
24°15'N, 82°26 W
24°17'N, 82°34'W
24°18'N, 82°33'W
24°24'N, 82°08'W
24°22'N, 80°57'W
24°05'N, 80°20'W
24°06'N, 80°12’W
24°05'М, 80°19'W
24°03'N, 79°36'W
23°43'М, 7932'W
23°34'N, 79°17'W
24°07'N, 79°28'W
24°34.7'N, 80°58.6’W
24°20'М, 82°56.5'W
24°19'N, 82°55'W
24°12.5'N, 82°50'W
24°02'N, 81°30’W
24°05'N, 81°20'W
23°51.9'N, 80°42.7'W
23°44'N, 81°14'W
26°38.4'N, 79°02.5'W

09°01.5'N, 76°53’W
21°02’N, 86°29’W
21°07'N, 86°21'W
18°58'N, 87°28'W
18°50.1’N, 87°31.5'W
18°45’N, 87°33’W
18°30'N, 87°37'W
17°02’N, 87°38.4'W
11°46’N, 67°05.7'W
11°36.9’N, 68°42’W
12°13.3’N, 72°50'W
11°37.8'N, 60°37.4'W
12°42’N, 61°05.5’W
13°11.2’N, 61°05.3’W
13°44'N, 61°03.1'W
13°45.5'N, 61°05.7'W
13°46.3'N, 61°05.4'W
16°05.3'N, 61°19.3'W
15°29.5'N, 61°11.5'W
18°29.3'N, 63°24.6’W
17°42.5'N, 77°58'W
17°18'N, 78'32'W
17°27'N, 78°10'W
17°13'N, 77°50'W
17°21.4'N, 77°34.8'W
25°44.5'N, 79°50.0’W

24°28.3'N, 77°29.5'W
23°14'N, 82°25'W

24°34'N, 83°16’W
23°02.5'N, 83°11'W

Depth
m

1390-1414
1394-1399
553-558
499-503
499-503
269-402

512
250-252
192
119
189
540-576
291-311
525-516
556
254-358
229-274
329-366
622
1706-1723
1556-1709
1080-1089
2276-2360
527-505

1281-963
567-570
155-205
970-988
695-772
466-649
715-787
296-329

1174-1108
684-1574
408-576
658-1126

18-744
156-201
231—430
201-589
384-963
683-733
457-503
686-723
457-558
622-823
521-658
595-824
805-1089

311

1597
1472

66
402

Gear

10’ OT
10’ OT
10’ OT
10" OT
10’ OT
10’ OT
10’ OT
10’OT
Triangular Dr.
Triangular Dr.
10’ OT
10’ OT
10’ OT
10’ OT
10’ OT
10201
10’ OT
10’ OT
10’ OT
10’ OT
10’ OT
10’ OT
10’ OT
10’ OT

40’ OT
10’ OT
10’ OT
Box Dr.
10’ OT
10’ OT
10’ OT
10’ OT
10’ OT
10’ OT
10’ OT
10’ OT
10’ OT
5’ Blake Tr.
Triangular Dr.
Scallop Dr.
Scallop Dr.
5’ Blake Tr.
5'Blake Tr.
5' Blake Tr.
10' OT
10’ OT
10’ OT
10’ OT
10’ OT
10’ OT

40' OT

62 QUINN
APPENDIX (continued)

AAA Е АЕ A ne I an

Sta. Depth

Ship no. Date Position (m) Gear

BLAKE 21 23°02'N, 83°13’W 525
BLAKE 36 23°13'N, 8916'W 154
BLAKE 43 24°08'N, 82°51'W 620
BLAKE 44 25°33'N, 84°35'W 986
BLAKE 47 28°42'N, 84°40'W 587
BLAKE 62 off Havana 146
BLAKE 230 2/20/1879 13°13.3’N, 61°18.8’W 848
BLAKE 299 3/10/1879 13°05'N, 59°39.7'W 256
ALBATROSS 871 off Martha's Vineyard 210
ALBATROSS 2135 2/27/1884 19°55'58"N, 75°47'07"W 457 Tangle bar
ALBATROSS 2150 4/9/1884 13°34'45"N, 81°21'10”W 699 Dredge & Tangle bar
ALBATROSS 2311 1/5/1885 32°55'N, 77°54'W 144 Large Blake Trawl
ALBATROSS 2312 1/5/1885 32°55'N, 77°54'W 161 Large Blake Trawl
ALBATROSS 2313 1/5/1885 32°53'N, 77°53'W 181 Large Blake Trawl
ALBATROSS 2314 1/5/1885 32°43'N, 77°51'W 291 Large Blake Trawl
ALBATROSS 2384 3/3/1885 28°45'N, 88°15'30'W 1719 Large Blake Trawl
ALBATROSS 2398 3/14/1885 28°45'N, 86°26’W 415 Large Blake Trawl
ALBATROSS 2415 4/1/1885 30°44'N, 79°26’W 805 Large Blake Trawl
ALBATROSS 2417 4/2/1885 33°18'30"N, 77°07'W 174 Large Blake Trawl
ALBATROSS 2594 10/17/1885 35°01'N, 75°12'W 293 Large Blake Trawl
ALBATROSS 2602 10/18/1885 34”38'30"N, 75°33'30"W 227 Large Blake Trawl
ALBATROSS 2644 4/9/1886 25°40'N, 80°00’W 353 Blake Dredge
ALBATROSS 2654 5/2/1886 27°57'30"N, 77°27'30"W 1207 Large Blake Trawl
ALBATROSS 2668 5/5/1886 30°58’30”М, 79°38'30"W 538 Large Blake Trawl
ALBATROSS 2751 11/28/1887 16°54'N, 63°12’W 1257 Large Blake Trawl
ALBATROSS 2754 12/5/1887 11°40'N, 58°33’W 1609 Large Blake Trawl
JOHNSON-
SMITHSONIAN
EXPEDITION 10 2/2/33 18°29'20’N, 66°05'30'W 220-293 9' Tangle
JOHNSON-
SMITHSONIAN
EXPEDITION 67 2/23/33 18°30’ 12”N, 65°45'48"W 329-512 4' Dredge
JOHNSON-
SMITHSONIAN
EXPEDITION 93 3/2/33 18°38'00"N, 65°09'30"W 640-732 3'Dredge
JOHNSON-
SMITHSONIAN
EXPEDITION 94 3/2/33 18°37'45"N, 6505'00"W 549-860 3' Dredge
JOHNSON-
SMITHSONIAN
EXPEDITION 102 3/4/33 18°50'30"N, 64°43'00"W 165-914 35' OT
JOHNSON-
SMITHSONIAN
EXPEDITION 104 3/7/33 18°30’40”М, 66°13’20”W 146-220 Oyster Trawl
ATLANTIS 1985 23°13'N, 81°22'W 704
ATLANTIS 2963C 2/25/38 22°07'N, 81°08 W 375 35' OT
ATLANTIS 2993 3/15/38 23°24'N, 80°44'W 1061 14'Blake Trawl
ATLANTIS 2999 3/17/38 23°10'N, 81°29’W 265421 10’ Blake Trawl

1|KMT = Isaacs-Kidd Midwater Trawl; OT = Otter Trawl; Scal. Dr. = Scallop Dredge.

MALACOLOGIA, 1979, 19(1): 63-76

APPAREIL GENITAL DE CARINARIA LAMARCKI (GASTROPODA HETEROPODA)

STRUCTURE ET AFFINITÉS
Micheline Martoja! et Catherine Thiriot-Quiévreux2

RESUME

L'étude de Carinaria lamarcki, menée au moyen de méthodes histologiques, a permis de
donner une premiere description de l'appareil génital femelle, de compléter les données
antérieures relatives au mâle et de comparer cette espèce représentative des Carinariidae à
d'autres types de Mésogastropodes.

L'appareil génital femelle est entièrement inclus dans la masse viscérale. L'ovaire, tubuleux et
ramifié, se prolonge par un oviducte proximal à allure de gonade indifférenciée puis par un
oviducte distal, simple conduit cilié. Le réceptacle séminal, qui fait suite, en est séparé par une
valvule. Aprés avoir donné naissance á un caecum, il forme des circonvolutions, aborde les
glandes annexes par leur extrémité antérieure et conflue avec elles en un carrefour commun á
l'ensemble. Il est tapissé de hautes cellules dont Газрес{ se modifie au contact des spermato-
zoides. La glande de l'albumine et la glande de la coque sont accolées latéralement l’une à l’une
à l’autre. Chacune est refermée en caecum à l'arrière et s'ouvre à l’avant sur la cavité palléale.
Leur tissu est formé d'un épithélium cilié doublé de faisceaux de cellules glandulaires. Les deux
glandes sont sillonnées par des gouttières ciliées où s'opère le tri des oeufs au cours de
l'élaboration des enveloppes puis du cordon ovigère. Une bourse copulatrice multifide se rat-
tache au vagin. Cet appareil génital femelle présente plusieurs caractères anatomiques et
histologiques identiques à ceux de Pterotrachea.

La spermatogénèse est caractérisée par des “cellules nourriciéres” au sens de Reinke
(1912), qui ne contractent des rapports avec les spermatozoïdes que dans la vésicule séminale.
L'appareil génital mâle ne diffère de celui des autres Mésogastropodes que par une migration de
la prostate à l’intérieur de la masse viscérale. La prostate est formée de nombreux tubules
débouchant sur une cavité unique; elle est traversée ventralement par le canal déférent qui

,

s'ouvre dans la cavité palléale.

INTRODUCTION

L'appareil génital des Carinaires est très
mal connu. Les seules données concernant la
femelle résultent des observations de Geg-
enbaur (1855) qui, en examinant des ani-
maux par transparence, reconnut l'ovaire,
l'oviducte, le pore génital et deux organes an-
nexes, l’un glandulaire, l’autre en ampoule.
Les illustrations de Tesch (1949) et de Fretter
& Graham (1962) n'apportent aucun complé-
ment a ce schéma. Les connaissances rela-
tives au male sont plus avancées. Selon
Tuzet (1936), la spermatogénése est double
mais la lignée atypique est abortive. Les voies
génitales internes comportent une prostate
(Gabe, 1965) et, comme chez les autres
Hétéropodes, un appendice glandulaire est
associé au pénis (Leuckart, 1853; Gegen-
baur, 1855; Gabe, 1965). Enfin, les oeufs sont
pondus en chapelets (Gegenbaur, 1855) et il
existerait des spermatophores (Van der
Spoel, 1972).

Or les Hétéropodes, auxquels appartien-

nent les Carinariidae, comportent deux autres
familles, Atlantidae et Pterotracheidae, qui
diffèrent sensiblement l’une de l’autre par
l'organisation de leur appareil génital (Gabe,
1951, 1965, 1966; Thiriot-Quiévreux &
Martoja, 1974, 1976) tout en présentant cer-
tains points communs avec les Mésogastro-
podes benthiques, en particulier les Littorines
(Martoja & Thiriot-Quiévreux, 1975). Nous
avons donc cherché a situer les Carinaires
dans cet ensemble en étudiant l'appareil
génital femelle de Carinaria lamarcki et en
complétant les données relatives au mâle.

MATÉRIEL ET MÉTHODES

Toutes les Carinaires ont été récoltées à
bord du Korotneff dans le plancton de la
région de Villefranche-sur-Mer (Méditerranée
occidentale) à l'exception d'un mâle juvénile
qui provient d'une campagne océanograph-
ique effectuée par le N.O. Knorr (Woods Hole
Oceanographic Institution) en Atlantique
Nord.

Institut Océanographique, 195 Rue Saint Jacques, 75005 Paris, France.

2Station Zoologique, 06230 Villefranche-sur-Mer, France.

64 MARTOJA ET THIRIOT-QUIÉVREUX

Les animaux ont été fixés in toto par le
mélange de Halmi, soit directement, soit
après mise en attente dans du formol salé. Ils
ont été inclus à la paraffine, coupés et étalés
en séries complètes.

Les méthodes suivantes ont été utilisées,
seules ou combinées entre elles (voir Martoja
& Martoja, 1967, pour l'exposé des tech-
niques):

—coloration à l’azan de Heidenhain; tri-
chrome de Prenant, variante de Gabe
(topographie générale);

—Coloration au bleu de toluidine (répartition
des acides nucléiques, métachromasie);
—réaction à l'acide periodique—Schiff (APS)
(détection des composés oxydables par
l'acide periodique et notamment des

glucides);

—coloration au bleu alcian a pH 3,2, colora-
tion de Ravetto au bleu alcian a pH
0,5-jaune alcian à pH 2,5 (étude des
mucines acides sulfatées et carboxylées);

—réaction à l’alloxane—Schiff (detection
globale des protéines).

L'étude anatomique a été réalisée à partir
de reconstitutions graphiques de coupes
sériées par les procédés de reconstruction
projective et d'isolement graphique (voir
Gabe, 1968 pour le détail des méthodes).

RÉSULTATS
Anatomie Microscopique

1. Nomenclature et topographie générale

La nomenclature de l'appareil génital des
Gastéropodes diffère selon les auteurs et
selon la position systématique des animaux.
Le choix en devient donc difficile dès que
l'organisation s’ecarte d'un schéma class-
ique. La terminologie de Ghiselin (1965),
basée sur la morphologie fonctionnelle et
applicable aux Prosobranches ou aux Euthy-
neures, devrait éliminer ces difficultés.
Toutefois le découpage des glandes annexes
femelles en trois unités ne correspond pas ici
aux données anatomiques et le terme d'ovi-
ducte utilisé pour le canal de ponte des
formes diauliques prête à confusion avec
l'acception traditionnelle.

Nous inspirant de plusieurs auteurs (Fretter
& Graham, 1962; Ghiselin, 1965; Franc,
1968), nous proposons pour Carinaria les
désignations suivantes:

1° pour l'appareil génital mâle, spermi-
ducte (= gonoducte coelomique) lui-

même divisé en spermiducte prévésicu-
laire, vésicule séminale et spermiducte
post-vésiculaire; prostate (= glande an-
nexe = gonoducte palléal des Mésogas-
tropodes à cavité palléale normalement
développée); gouttière spermatique; ap-
pareil copulateur composé d'un pénis et
d'un appendice glandulaire;

2” pour l'appareil génital femelle, oviducte
proximal et oviducte distal (= gonoducte
coelomique) caractérisés par leur struc-
ture histologique; réceptacle séminal et
bourse copulatrice identifiés par la dispo-
sition des spermatozoïdes; glande de
l'albumine et glande de la coque (=
glandes annexes = gonoducte palléal des
autres Mésogastropodes), définies
d'après le trajet des oeufs; vagin et canal
de ponte.

Les Carinaires sont gonochoriques. Dans
les deux sexes, la gonade occupe la région
dorsale du “nucleus,” terme ancien qui
désigne, dans ce groupe, la masse viscérale;
les organes annexes sont situés à la base et
le gonoducte coelomique traverse la glande
digestive sur toute sa hauteur. Le spermi-
ducte effectue un parcours légèrement
oblique et s'accole à l'extrémité postérieure
de la prostate. Le pore génital s'ouvre au fond
et à droite de la cavité palléale. Une gouttière
spermatique le relie à l'appareil copulateur,
appendu sur le flanc droit du corps, au-
dessous du nucléus. L'oviducte prend une
direction presque horizontale, s'élargit en un
réceptacle séminal et aborde les glandes
annexes par leur extrémité antérieure; com-
me dans quelques autres espèces (voir
Creek, 1951), la dénomination de réceptacle
séminal s'appuie ici sur une donnée fonction-
nelle. Une bourse copulatrice est rattachée au
vagin. Le pore génital dédoublé est situé com-
me Porifice mâle, au fond et à droite de la
cavité palléale. Il se prolonge par deux gout-
tières jusqu'au sommet d'une papille qui
n'existe pas chez le mâle.

2. Appareil génital mâle (Fig. 1)

L'emplacement du testicule est délimité par
la paroi du corps, la glande digestive, l'intestin
et le rein. Sa forme est celle d'une lentille bi-
convexe très régulière. Du centre de sa face
ventrale émerge un court spermiducte
prévésiculaire qui se dilate progressivement
chez l'adulte pour faire place à une vésicule
séminale. Celle-ci est un long tube, large et
distendu qui, sous l'effet de la réplétion, peut
décrire deux ou trois circonvolutions dans sa

APPAREIL GÉNITAL DE CARINARIA 65

testicule

glande
digestive

vesicule seminale

prostate

gouttiere
spermatique

rein

pericarde

branchies

penis

appendice glandulaire

FIG. 1. Organisation de l'appareil génital mâle. Le “nucléus” (= masse viscérale) est représenté en coupe
sagittale. Les connexions et orifices sont arbitrairement ramenés dans un même plan.

partie terminale. Le spermiducte post-vésicu-
laire est très court et englobé dans une
échancrure latérale de la prostate. Il y dé-
bouche au niveau du tiers postérieur en for-
mant une valvule. Chez l'animal impubere,
aucune particularité anatomique ne permet
d'identifier la future vésicule séminale: la divi-
sion du spermiducte en trois segments re-
pose donc uniquement sur des bases fonc-
tionnelles, ce que confirme l'examen histo-
logique.

Réduite chez le jeune, la prostate atteint
chez l'adulte des dimensions voisines de cel-
les du testicule. C'est une glande oblongue,
pointue à l'avant, bifide à l'arrière, les deux
branches de la fourche enserrant les circon-
volutions distales de la vésicule séminale.
Avant la maturité génitale, elle se présente
comme un sac vide, à peine lobé. A la
puberté, les invaginations de la paroi qui
délimitaient les lobes se multiplient et pro-
gressent à l'extérieur et à l'intérieur de
l'organe. Ce processus aboutit à la formation
de tubes jointifs rayonnant autour d'une cavité
centrale restreinte par rapport à celle de
l'animal impubere.

L'orifice génital se présente comme une
fente transversale bordée de deux lèvres. La
lèvre antérieure est raccordée au toit de la
cavité palléale. La lèvre postérieure se pro-
longe par deux bourrelets tégumentaires sail-
lants et parallèles qui délimitent la gouttière
spermatique et réalisent la jonction entre la
prostate et le pénis. A ce dernier, est accolé
un appendice glandulaire, dépourvu de con-
nexion anatomique avec le reste du système

génital, doté d'un orifice unique et indépend-
ant.

3. Appareil génital femelle (Fig. 2)

Par son emplacement, sa forme et son vol-
ume, l'ovaire est identique au testicule. Le
départ de l’oviducte se situe, de la même
façon, au centre de sa face ventrale.

L’oviducte est un conduit étroit, de calibre
uniforme qui, après avoir traversé la glande
digestive, longe la face dorsale de la glande
de l’albumine sans s’y raccorder. ll dépasse
l'extrémité antérieure de cette glande et
débouche, en formant une valvule, dans un
segment dilaté qui fonctionne comme récep-
tacle séminal. Cette dilatation est piriforme et
un caecum effilé s’en détache à proximité de
la valvule. Son diamètre diminuant peu à peu,
le réceptacle séminal devient un long tube qui
s'enroule en un peloton serré situé en avant
des glandes annexes. La partie terminale du
tube se dégage de la masse des circonvolu-
tions, se dirige vers l'arrière, s'enfonce dans
une dépression latérale de la glande de
l’albumine et fusionne avec un canal qui, à ce
niveau, est commun aux deux glandes an-
nexes. L’oviducte proximal, l'oviducte distal et
le réceptacle séminal sont identifiables des le
stade impubere, contrairement aux segments
du gonoducte mále.

La glande de l’albumine et la glande de la
coque sont grossièrement fusiformes. Elles
sont disposées cóte a cóte et leur grande axe
est parallèle à celui de Гапита!. Chacune
s'ouvre à l'avant et se referme en caecum а
l'arrière. Elles ne sont tout à fait indépend-

66 MARTOJA ET THIRIOT-QUIÉVREUX

|
glande de
la coque

glande de
l'albumine

carrefour

réceptacle
seminal

oviducte

bourse copulatrice
с LA
vagin

canal de ponte

FIG. 2. Diagramme des voies génitales femelles. Pour la clarté du schéma, quelques modifications ont été
apportées: plus d'importance a été donnée à la région du carrefour; les deux glandes annexes ont été
séparées dans leur zone antérieure; les circonvolutions du réceptacle séminal ont été dissociées des

diverticules de la bourse copulatrice.

antes l’une de l’autre que dans leur région
postérieure. Dans leur région antérieure, elles
sont à la fois imbriquées et desservies par un
canal unique aplati dorso-ventralement et
muni de deux gouttières ciliées latérales,
diamétralement opposées. La gouttiere
gauche correspond à la glande de la coque;
la gouttière droite correspond à la glande de
l’albumine et reçoit le réceptacle seminal,
d'où l'existence d'un carrefour où se rejoig-
nent les divers segments. En se plissant et en
se subdivisant, le canal commun donne
naissance à des fentes qui se prolongent vers
l'arrière et forment les cavités des glandes.
Les deux gouttières ciliées se subdivisent de
la même façon si bien que ces cavités sont
sillonnées par de multiples gouttières paral-
leles. En avant du carrefour, le canal s'incurve
en un V de plus en plus fermé puis se scinde
en deux conduits où s'engagent les gouttieres
latérales. Le conduit gauche, issu de la
glande de la coque, devient un canal de
ponte. L'autre, plus court, constitue un vagin.
A quelque distance de l'orifice génital, un
diverticule multifide, qui joue le róle de bourse
copulatrice, se rattache au vagin; ses caeca
sont intimement mélés aux circonvolutions du
réceptacle séminal mais n'ont aucune com-
munication avec elles.

Une telle organisation implique qu'une
partie des spermatozoides recus du conjoint
et les oeufs, aux divers stades de leur matura-
tion, empruntent les mémes voies, le tri en
étant assuré par les gouttiéres ciliées du
canal commun et des cavités qui en dérivent.
A l'intérieur de chaque glande, les oeufs ac-
complissent un parcours complexe qui part du
carrefour et y revient. Quant aux spermato-
zoides, ils sont répartis entre deux réservoirs
dont l'un est intégré au tractus génital et
l’autre, anatomiquement individualisé. Il serait
intéressant de savoir s'ils se divisent
d'emblée en deux lots ou si tous passent par
la bourse copulatrice pour y acquérir leur
capacitation, par exemple, avant de
s'engager dans le réceptacle séminal. La dis-
position topographique permet seulement de
constater que les oeufs ne peuvent rencontrer
les spermatozoïdes emmagasinés dans
la bourse copulatrice.

Histologie
1. Appareil génital mâle

Les travaux de Tuzet (1936) et de Gabe
(1965) comportent la description complète de
la spermatogénèse et du système génital
mâle. Nous n’envisageons donc ici, que

APPAREIL GÉNITAL DE CARINARIA 67

quelques points qui, selon nos observations,
doivent être reconsidérés.

a) Spermatogénèse: certains secteurs
des tubes séminifères sont occupés par des
cellules différentes des cellules germinales
(Fig. 3D). Ces éléments se distinguent des
spermatozoïdes bien avant la puberté, non
seulement par leur noyau plus gros et plus

clair mais par leur cytoplasme plus abondant
et nettement APS-positif. Chez l'adulte, leur
noyau ne s'est pas modifié mais leur cyto-
plasme s'est accru: elles sont ellipsoïdes,
mesurent 10 um sur 8 environ et sont
pourvues d'un noyau sphérique parfaitement
normal d'environ бит de diamètre. La
chromatine dessine un réseau lâche et il y a

FIG. 3. Appareil génital mâle. A. Coupe sagittale de la prostate d'un mâle infantile (APS-hématoxyline,
x75) (cp, cavité palléale; gd, glande digestive; г, rein). В. Coupe sagittale de la prostate d'un mâle adulte
(même technique; même grandissement). С. Gouttière spermatique (Bleu alcian-APS-hématoxyline; x 560).
D. Coupe de testicule (APS-hématoxyline; х560). Remarquer au centre, les “cellules nourriciéres.” Е.
Coupe de vesicule séminale (APS-hématoxyline; x 150). Е. Groupe de spermatozoïdes entourant une
“cellule nourriciére” dans la vésicule séminale (APS-hématoxyline; x 1400).

68 MARTOJA ET THIRIOT-QUIÉVREUX

un ou deux petits nucléoles. Après réaction à
l'APS, le cytoplasme est coloré en rose pâle
et contient quelques minuscules grains tres
rouges. La paroi elle-méme est fortement
réactive et, de ce fait, tres visible.

Les cellules ellipsoides suivent le méme
trajet que les spermatozoides et parviennent
intactes dans les voies génitales. Dans le
spermiducte prévésiculaire, elles sont mélées
aux spermatozoïdes qui, eux-mêmes, forment
des pelotons. Dans la vésicule séminale, une
organisation précise s'établit: tous les sperm-
atozoides se regroupent en faisceaux autour
des éléments en question, la tête dirigée vers
eux (Fig. 3E). A partir de ce moment, les
noyaux des cellules ellipsoides deviennent
vésiculeux, les grains intracytoplasmiques se
résorbent et la paroi cellulaire perd son
caractére APS-positif (Fig. 3F). Aucune
image de cytolyse complète n'a, toutefois, été
observée. Sans doute en raison d'un transit
rapide, ni ces cellules, ni les spermatozoïdes
n'ont été vus dans la prostate. Il ne nous a
donc pas été possible de déterminer à quel
moment cesse leur association. Seuls les
spermatozoïdes ont été retrouvés dans les
voies génitales des femelles fécondées.

b) Voies génitales: une valvule, con-
stituée aux dépens de la zone terminale du
spermiducte post-vésiculaire, est interposée
entre ce segment et la prostate. A ce niveau,
les cellules épithéliales deviennent plus
hautes et sont dépourvues des grains de
pigment noir très abondants dans le reste du
spermiducte; leur ciliature est aussi plus
développée. L'épithélium repose sur une
basale très épaisse et plissée et, surtout, il est
entouré d'un important manchon de fibres
conjonctives qui n’a d’équivalent ni autour du
spermiducte proprement dit, ni autour des
tubes prostatiques.

Au stade juvénile, la paroi du sac prosta-
tique est faite d'un épithélium simple, non cilié
(Fig. ЗА). L'approche de la puberté se mani-
feste d’abord au niveau des noyaux qui, alter-
nativement, s'allongent ou au contraire s'ar-
rondissent, Les premiers grains de sécrétion
n'apparaissent que plus tard. La prostate de
l'adulte est une glande ramifiée (Fig. ЗВ).
Chaque tube est constitué d'un epithelium
pseudo-stratifié comportant des cellules
ciliées peu visibles et de grandes cellules
glandulaires dont les caractères ont été
décrits par Gabe. Les sécrétions déversées
par les tubes sont collectées dans une cavité
centrale où s'ouvrent ventralement d'une part
la valvule spermiductaire, d'autre part la fente

qui débouche sur la cavité palléale. Entre les
deux s'étend une gouttière qui représente le
canal déférent. Les cellules ciliées y devien-
nent prépondérantes par rapport aux cellules
glandulaires; elle est doublée extérieurement
d'une tunique conjonctive prolongeant le
manchon de la valvule. Dans l'épithélium qui
borde la fente, les cellules ciliées restent très
développées et les cellules glandulaires
caractéristiques des tubes prostatiques sont
remplacées par des mucocytes. Sur le plan
fonctionnel, il paraît évident que les sperma-
tozoides sont drainés de la valvule à la fente,
par la canal déférent, sans circuler dans les
tubes glandulaires où, d'ailleurs, on n'en
trouve jamais. C'est durant ce court trajet
qu'ils se méleraient aux sécrétions prostat-
iques.

La gouttière spermatique est délimitée par
deux bourrelets édifiés à partir de l'épithélium
de surface. Chacun est formé de hautes cel-
lules pourvues d'une ciliature très développée
(Fig. 3C).

2. Appareil génital femelle

a) Ovaire: comme le testicule, l'ovaire
(Fig. 4A) est dépourvu de thèque conjonctive
mais ne présente pas la moindre imbrication
avec les tissus voisins. Comme le testicule
également, il est constitué de tubes conver-
geant en direction d'un point médio-ventral.
Les tubes sont séparés par de nombreuses
cellules conjonctives libres chez l'animal im-
pubère alors qu'ils sont jointifs chez l'adulte.
Chaque tube comporte une tunica propia sur
laquelle repose l'épithélium germinatif. Le
déroulement de Гоодепёзе est conforme au
schéma classique (voir Raven, 1972). Il y a
lieu de noter seulement que toute activité
mitotique des oogonies semble cesser chez
l'animal parvenu au stade de l'ovulation, qu'il
n'existe pas de cellules folliculaires mais
quelques petites cellules coniques qui pour-
raient être des cellules nourricières et que
l'oocyte en prévitellogénèse est doté d'un
“corps vitellin” important; la nature de ce
dernier reste a préciser.

Lors de l'ovulation, l'oocyte est une cellule
légèrement amiboide d'une cinquantaine de
um de diamètre, peu chargée en vitellus. La
vésicule germinative, au contour dentelé,
renferme un unique nucléole hétérogène
comportant une sphère dense excentrique.
Les plaquettes vitellines sont très petites et
leur réactivité à l'égard de ГАР$ est particu-
lièrement intense.

APPAREIL GÉNITAL DE CARINARIA 69

CE ee AA 44

E ©: da AR |

FIG. 4. Appareil génital femelle. A. Coupe de l'ovaire (trichrome de Prenant-variante de Gabe; x 140) (a,
artère génitale). В. Oviducte proximal (APS-hématoxyline; x 400). С. Oviducte distal (trichrome de Prenant-
variante de Gabe; х400). D. Valvule séparant l’oviducte distal (0) du réceptacle séminal (rs) (APS-
hématoxyline; x 200). E. Réceptacle séminal (trichrome de Prenant-variante de Gabe; 560). Remarquer
'agencement des spermatozoïdes le long de la paroi. Е. Bourse copulatrice (APS-hématoxyline; x 560).
Remarquer l'agencement différent des spermatozoïdes.

b) Oviducte: l'examen histologique т-
pose de diviser l'oviducte en deux segments.
L’oviducte proximal est constitué d'une
musculeuse externe assez importante qui
s’epaissit peu à peu à partir de l'ovaire, d'une
tunique conjonctive moyenne et d’une rangée
continue de cellules internes (Fig. 4B). Celles-
ci ne sont pas ciliées. Elles sont arrondies et,

de ce fait, disjointes. Caractérisées par un
rapport nucléoplasmique très élevé, elles
ressemblent de près aux gonocytes si bien
que ce segment semble en réalité n'être
qu'un prolongement inactif de l'ovaire.

Sans aucune transition, l’oviducte proximal
fait place à l’oviducte distal dont la structure
est différente (Fig. 4C). Les fibres musculaires

70 MARTOJA ET THIRIOT-QUIEVREUX

moins nombreuses et les fibres conjonctives,
au contraire plus nombreuses, sont mêlées.
Cette tunique musculo-conjonctive entoure
un épithélium cylindrique cilié banal. Les cel-
lules à allure de gonocytes disparaissent to-
talement.

Selon toute vraisemblance, le mode de
propulsion des oeufs change à partir de l'ovi-
ducte distal, les courants ciliaires prenant le
relai du péristaltisme qui, d’après l'allure de la
musculeuse, se manifesterait dans l'oviducte
proximal.

c) Réceptacle séminal: l'oviducte pénètre
à l’intérieur du réceptacle seminal et les épi-
thelium des deux segments s'accolent par leur
base pour former une valvule (Fig. 4D). Le
tissu conjonctif n'entre pas dans la constitution
de cette dernière qui est donc très différente de
la valvule prostatique.

La paroi du réceptacle séminal, faite d'une
tunique musculo-conjonctive et d'un épithéli-
um, entoure une lumière très vaste au contour
festonné. L'épithélium est, en effet, marqué
de plis très réguliers formés par l'allonge-
ment de certains groupes de cellules. Mise à
part leur différence de hauteur, toutes ces cel-
lules sont identiques. Elles portent une courte
ciliature et sont dépourvues de sécrétions fig-
urées. Chez le jeune, leur zone apicale ren-
ferme de petits grains de pigment noir qui ne
sont plus visibles chez l'adulte. Au contact
des spermatozoïdes, les cellules épithéliales
subissent des modifications qui se traduisent,
sur pièces fixées, par l'apparition de “уаси-
oles” (Fig. 4E). Le caecum présente une
structure proche de celle de l'organe princi-
pal. Toutefois, la lumière en est plus réduite.
Enfin, dans le prolongement rectiligne qui re-
joint le canal commun, il n'y a plus de plis
épithéliaux. Les cellules cubiques, très régu-
lières, ne renferment ni inclusions ni “vacu-
oles” mais portent une ciliature très dével-
oppée (Fig. 6B).

Chez la femelle fécondée, les spermato-
zoides sont alignés perpendiculairement a
l'épithélium du réceptacle séminal. Les têtes
sont dirigées vers celui-ci et sont en contact
étroit avec lui. De tels alignements sont rares
dans le prolongement rectiligne qui apparaît
plutôt comme une région de transit. Quant au
caecum, il reste constamment vide. Au mo-
ment de la ponte, les oeufs traversent le
réceptacle séminal. Les images les montrant
entourés de spermatozoïdes libres dans la
lumière s'observent surtout dans le pro-
longement rectiligne et c'est probablement à

ce niveau que s'opère la fécondation (Fig.
6B).

d) Bourse copulatrice: la bourse copu-
latrice (Fig. 5B) diffère sensiblement du ré-
ceptacle séminal. Dans la tunique musculo-
conjonctive qui entoure le canal principal et
les canaux secondaires de cet organe ramifié,
les fibres musculaires sont beaucoup plus
nombreuses qu’ autour du réceptacle séminal.
Cette tunique est plus réduite à l'extrémité
borgne des diverticules. L'ensemble est
tapissé d'un épithélium cilié (Fig. 4F). Selon
les individus, les cellules sont aplaties ou, au
contraire, étirées en hauteur mais, en aucun
cas, on ne remarque ni sécrétions, ni “vacu-
oles” signalétiques de réactions cellulaires.

Les spermatozoïdes se trouvent soit en
désordre dans la cavité, soit à proximité de
l'épithélium. Leur alignement est alors moins
rigoureux que dans le réceptacle séminal et
surtout, il ne s'établit aucun contact entre eux
et la paroi de l'organe.

e) Glandes annexes: les deux volumineu-
ses glandes annexes ne sont séparées des
tissus voisins par aucune thèque conjonctive.
Elles offrent, sur coupes, un aspect massif,
leurs cavités étant réduites à d'étroites fentes
dont la disposition est extrêmement précise
(Figs. 5A à C). En section transversale, la
lumière de la glande de la coque est bipec-
tinée par rapport à un axe dorsoventral; des
fentes limitées par un simple épithélium alter-
nent avec des fentes associées du paren-
chyme glandulaire. L'organisation de la
glande de l'albumine apparaît mieux en sec-
tion sagittale. Les fentes, symétriques par
rapport à un axe longitudinal, sont alterna-
tivement courtes et longues; toutes sont
associées à du рагепспуте glandulaire.
Les extrémités de toutes les fentes sont
différenciées pour former des gouttières
ciliées. Chez les femelles fixées en période
de ponte, c'est à l’intérieur de ces gouttiéres
que se trouvent la majorité des oeufs (Fig.
6).

Plusieurs tissus concourent á l'édification
des glandes annexes. Ils sont les mêmes
dans les deux cas. Leur répartition dans
l'espace est différente mais également
rigoureuse. Comme pour les fentes, il existe
une symétrie et une périodicité remarquables.

L'épithélium pavimenteux forme le canal
commun et certaines fentes de la glande de la
coque. Il borde l'axe longitudinal de la glande
de ГаБитте et l'axe vertical de la glande de
la coque. Ses cellules ont environ 5 um de

APPAREIL GÉNITAL DE CARINARIA TA

NE TEE

FIG. 5. Appareil genital femelle. A, B, C. Coupes parasagittales de la base de la masse viscerale (bleu
alcian-APS-hématoxyline; x35) (bc, bourse copulatrice; cp, cavité palléale; ga, glande de l'albumine; gc,
glande de la coque; p, papille; rs, réceptacle séminal).

haut, reposent sur une basale bien visible,
portent une ciliature assez longue mais peu
dense et renferment parfois de minuscules
grains naturellement colorés en ocre. Cet
épithélium se distingue très tôt des autres
régions: chez l'animal impubere, il est
cubique, non cilié et doublé d'une basale très
épaisse.

Le tissu glandulaire borde toutes les fentes

dans la glande de l’albumine et la majorité
d’entre elles dans la glande de la coque.
Avant la puberté, ce tissu est représenté
par un épithélium simple, cylindrique non cilié,
riche en cellules toutes identiques et caractér-
isées par une très haute teneur en ARN.
Ultérieurement, certaines cellules deviennent
piriformes et s'étirent de telle sorte que la
partie renflée qui contient le noyau s'enfonce

72 MARTOJA ET THIRIOT-QUIEVREUX

sous la couche cellulaire superficielle tandis
que l'apex garde le contact avec la lumière.
Chez l'adulte, le tissu glandulaire est formé
d'un épithélium cilié associé à des faisceaux
de cellules sous-jacentes; celles-ci sont
pourvues de prolongements qui traversent
l’epithelium et déversent leurs sécrétions di-
rectement dans la lumière (Fig. 6C et D).A
l'échelle cellulaire les éléments glandulaires

wu."

Le С
.

se présentent sous deux aspects. Certaines
cellules glandulaires ont un volumineux
noyau et un ergastoplasme très développé.
Les sécrétions, indécelables dans le corps
cellulaire au microscope photonique, ne sont
visibles que dans le prolongement cytoplas-
mique, sous forme de petits grains toujours
individualisés, fortement APS-positifs et
dépourvus de protéines histochimiquement

FIG. 6. Evolution de l'oeuf dans les voies génitales femelles (A à E, trichrome de Prenant-variante de Gabe;
x 140). A. Oocytes traversant la zone dilatée du réceptacle séminal après l'ovulation. В. Oocytes entourés
de spermatozoïdes dans le segment rectiligne du réceptacle séminal. C. Oeufs fécondés abordant la zone
muqueuse de la glande de l'albumine. D. Oeufs pourvus de leurs enveloppes dans la zone muqueuse de la
glande de la coque. E. Cordon ovigère dans la zone dorsale de la glande de la coque.

APPAREIL GÉNITAL DE CARINARIA 73

décelables. Ceux de la glande de l’albumine
sont légèrement carboxylés. Les autres cel-
lules glandulaires ont un noyau plus réduit,
souvent frippé. Le cytoplasme est masqué
par les sécrétions qui occupent à la fois le
corps cellulaire et le prolongement. Ces
sécrétions ont, dans les deux glandes, une
allure spongieuse ou floconneuse; elles sont
faiblement APS-positives et riches en groupe-
ments sulfatés. Il s’agit donc de mucoytes
typiques élaborant des mucines très acides.

Les gouttières ciliées résultent d'une modi-
fication des cellules épithéliales qui devien-
nent plus hautes (30 à 40 ит sur les bords,
20 um au fond de la concavité) et qui ac-
quiérent une puissante ciliature (15 ит) (Fig.
6E). Lorsqu’elles sont coupées transversale-
ment, les gouttières ont toujours un contour
arrondi bien qu'elles ne soient doublées
d'aucune assise conjonctive. La plupart sont
entourées de faisceaux de cellules glandu-
laires mais celles qui prolongent les épithé-
liums pavimenteux, dans la glande de la
coque, sont presque partout constituées d’un
épithélium simple.

Enfin des fibrocytes et des cellules ami-
boides comblent les espaces laissés libres par
les autres tissus. Chez les animaux de grande
taille, ces éléments deviennent extrêmement
abondants.

Les oeufs s'engagent d’abord dans les plis
muqueux de la glande de ГаБитте. Leur
aspect y est identique à celui des oocytes
contenus dans l’oviducte ou le réceptacle
séminal (Fig. 6D). Dans les autres plis de cette
glande, les grains de sécrétions viennent
s'accoler individuellement autour de chaque
oeuf; ils conflueront plus tard en une masse
homogène aux limites imprécises. Dans la
glande de la coque, trois phénoménes se
produisent successivement: les sécrétions
diffuses, élaborées au moins en partie dans la
glande de l’albumine, se condensent si bien
que l'épaisseur de l'enveloppe se réduit de
30 um à 7 ит environ; ensuite, une très fine
pellicule intensément colorable se dépose à
son tour sur cette première enveloppe (Fig.
6C); enfin, une sécrétion lâche et floconneuse
enrobe plusieurs oeufs alignés, les solidari-
sant ainsi en chapelets (Fig. 6E). Les aspects
correspondant aux phases de l'élaboration
des membranes s'observent à tous les niveaux
de la glande de la coque, ce qui traduit la com-
plexité du trajet parcouru par les oeufs. Il en
résulte que, en l'absence d'étude histochimi-
que détaillée, le lieu d’édification des différ-
entes enveloppes de l'oeuf n’a pu être pré-
cisé.

f) Papille: la papille n'est qu’une excrois-
sance banale soutenue par un tissu conjonctif
láche et recouvert d'un tégument identique á
celui de la cavité palléale (Fig. 5A). Les deux
gouttières qui sillonnent sa surface sont
revêtues d'un épithélium cylindrique cilié,
doublé d'assez nombreuses fibres conjonc-
tives associées en réseau.

DISCUSSION
Appareil génital mâle

Certaines de nos observations sur le
déroulement de la spermatogénèse et la
structure des voies génitales diffèrent de
celles de nos devanciers. Ainsi, la notion de
lignée atypique abortive introduite par Tuzet
(1936) doit être nuancée. En effet, les cellules
distinctes de la lignée germinale typique con-
tractent des rapports particuliers avec les
spermatozoïdes. Le fait que ces rapports ne
s'établissent que dans la vésicule séminale
impose également de les distinguer des cel-
lules de Sertoli bien connues chez divers
Gastéropodes. Les cellules ellipsoides de la
Carinaire sont, en réalité, très comparables à
celles qui ont été décrites sous le nom de
“nurse-cells” chez Littorina spp. par Reinke
(1912) puis Linke (1933). L'interprétation de
ces cellules “nourricieres” est loin d'être
évidente comme le montre l'analyse de
Roosen-Runge (1977). Leur extréme rareté
parmi les Mollusques accentue l’intérênt d'une
similitude entre la Carinaire et les Littorines.

C'est certainement а des défectuosités du
matériel examiné qu'il faut attribuer certains
points de la description de Gabe (1965) que
nous ne confirmons pas et qui concernent la
structure de la prostate, la position de Гопйсе
génital et la gouttière spermatique. Cette de-
scription repose, en effet, sur l'observation de
coupes parasagittales (Gabe, 1965: 1035)
alors que l'examen de coupes sagittales est
indispensable à la compréhension du sys-
tème. Les rectifications que nous apportons
montrent que l'appareil génital mâle de
Carinaria lamarcki présente une organisation
tout à fait classique de Prosobranche Méso-
gastropode. La persistance de caractères
primitifs comme l'ouverture de la prostate sur
la cavité palléale et la présence d'une gout-
tière spermatique également ouverte le rap-
proche d'un type bien connu, par exemple
chez les Littorines. Seule apparaît inhabituelle
la position de la prostate à l'intérieur de la

74 MARTOJA ET THIRIOT-QUIÉVREUX

masse viscérale et non au toit de la cavité
palléale. Cette migration peut être due à la ré-
duction de la cavité palléale, caractéristique
des Carinariidae. Néanmoins, il est remar-
quable que l'organe soit séparé du spermiducte
par une valvule alors que ce dispositif est
inséré d'ordinaire entre le spermiducte et le
segment rénal des voies génitales, comme le
souligne Purchon (1968). Des recherches
embryologiques devraient donc déterminer si
la prostate des Carinaires est bien l'homo-
logue du gonoducte palléal des autres Proso-
branches. La structure de cette prostate est
d’ailleurs assez rare et rappelle, dans une
certaine mesure, celle de Bythinia ou les
tubes prostatiques s'ouvrent séparément
dans un canal unique (Lilly, 1953). Enfin,
l'appareil copulateur, tel qu'il est décrit par
Gabe (1965) et que nous l'avons observé
nous-mêmes, présente plusieurs points com-
muns avec celui des Littorines. Ce rappro-
chement avait déjà été fait pour d'autres
Hétéropodes (Martoja & Thiriot-Quiévreux,
1975).

Appareil génital femelle

La morphologie de l'ovaire, le déroulement
de l’oogénèse sont conformes au schéma
classique (voir Raven, 1972) et l'aspect de
l'oviducte proximal appuie l'opinion de Linke
(1933) selon laquelle cette zone du tractus
génital ne serait, chez les Prosobranches,
qu'un segment indifférencié de la gonade.

L'organisation des voies génitales propre-
ment dites est, au contraire, très particulière à
plusieurs égards. Le gonoducte “palléal” a,
comme chez le mâle, subi une migration vers
la masse viscérale mais, ici, les relations
topographiques entre les divers segments
s'en trouvent modifiées par rapport au type
Prosobranche. Ainsi, l'ensemble oviducte-ré-
ceptacle séminal est situé en avant des glan-
des annexes et les aborde par leur extrémité
antérieure. La position de l’orifice génital à
l'avant de ces glandes étant conservée,
chacune se termine en caecum vers l'arrière
et les oeufs doivent parcourir un ou plusieurs
allers et retrours à travers leurs cavités.
D'autre part, les deux glandes sont accolées
et même imbriquées sur une certaine longu-
eur, ce qui nécessite le tri des produits
génitaux par des gouttières spécialisées. Or,
chez les Prosobranches, les divers segments
sont habituellement alignés et les oeufs pro-
gressent régulièrement de l'un a l’autre dans
le sens postéro-antérieur; c'est sur ce modèle

simple qu'est construit le tractus génital des
Atlantidés (Thiriot-Quievreux & Martoja,
1974). Ceci correspond à l’évolution phy-
logénique de la lignée des Hétéropodes qui
présente différents degrés d'adaptation à la
vie pélagique, les Atlantidés étant les plus
primitifs. Par sa complexité et la position de
ses connexions, l'appareil génital femelle
n'est pas sans évoquer l'organisation de cer-
tains Opisthobranches (voir Ghiselin, 1965), le
gonochorisme constituant toutefois une dif-
férence essentielle.

D’autres caractères anatomiques retien-
nent l'attention sans être aussi exceptionnels.
L'absence de canal gono-péricardique, fré-
quente ches les Mésogastropodes, est con-
stante chez les Hétéropodes qu'il s'agisse
d'Atlantidae (Thiriot-Quiévreux & Мапода,
1974, 1976), de Pterotrachea (Gabe, 1951)
ou de Firoloida (Gabe, 1966). La tendance
a la diaulie notée chez Carinaria existe
également dans certaines espèces d'Atlanti-
dae où le réceptacle séminal est pourvu
d'un orifice propre. Quant aux réservoirs
à spermatozoïdes, le nombre et la posi-
tion en sont très variables chez les Proso-
branches (Johansson, 1956, 1957) et cette
variabilité se manifeste au sein même des
Hétéropodes. Carinaria possède à la fois une
bourse copulatrice et un réceptacle séminal
alors que les autres Hétéropodes possèdent
seulement un réceptacle séminal. Chez
Carinaria, ce dernier n'est qu'un segment de
l’oviducte; une disposition analogue a été sig-
nalée dans trois espèces de Littorinoidea (voir
Creek, 1951) et chez les Pterotracheidae
(Gabe, 1951, 1966). La ressemblance avec
cette derniére famille est accentuée par la
présence d'une valvule. Enfin, l'existence
d'un caecum sans signification fonctionnelle
apparente et qui représente peut-être un
organe vestigial, se limite à Carinaria et
Pterotrachea.

Du point de vue de l'anatomie microscopi-
que, la symétrie et la périodicité qui caractér-
isent la répartition des catégories cellulaires
dans les glandes annexes, semblent peu
communes. Leur structure histologique est,
en revanche, très classique. On sait que ces
glandes annexes consistent ou bien en un
épithélium simple doublé d'éléments glandu-
laires sous-jacents, ou bien en un épithélium
pseudostratifié contenant lui-même les cel-
lules glandulaires. Celles de Carinaria cor-
respondent au premier type, comme celles de
Pterotrachea; ces deux genres s'opposant
aux Atlantidae et à Firoloida qui appartien-

APPAREIL GÉNITAL DE CARINARIA 75

nent au second type. De même, la paroi du
réceptacle séminal est assez proche de celle
de Pterotrachea mais différente de l'épithéli-
um cubique banal des autres Hétéropodes.
Néanmoins, nous n'y avons observé aucune
image menant à croire qu'elle soit le siège
d'une phagocytose et l’activité cellulaire que
traduit l'existence de vacuoles au contact de
spermatozoïdes pourrait être en rapport avec
un rôle nourricier.

CONCLUSION

L’appareil génital male de Carinaria con-
serve un caractére primitif. Son organisation
est celle d'un Mésogastropode, l'originalité
résidant en une migration de la glande an-
nexe vers la masse viscérale. L'appareil
génital femelle est, lui, beaucoup plus modi-
fié, une migration analogue entraînant un
bouleversement des connexions anatomi-
ques par rapport au type Mésogastropode.

Parmi les Hétéropodes, c'est avec
Pterotrachea que Carinaria présente le plus
de points communs mais les particularités de
sa spermatogénèse le rapprochent du genre
Littorina.

RÉFÉRENCES BIBLIOGRAPHIQUES

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GABE, M., 1951, Données histologiques sur
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MARTOJA, M. 8 THIRIOT-QUIEVREUX, C., 1975,
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76

MARTOJA ET THIRIOT-QUIÉVREUX
ABSTRACT

GENITAL APPARATUS OF CARINARIA LAMARCKI (GASTROPODA
HETEROPODA): STRUCTURE AND AFFINITIES

Micheline Martoja and Catherine Thiriot-Quiévreux

A histological study of Carinaria lamarcki provides the first description of the female reproduc-
tive system and some new data on the male reproductive system. This species which is repre-
sentative of Carinariidae is compared with some other types of mesogastropods.

The whole female reproductive system is enclosed in the visceral mass. The ramified tubular
ovary extends to form a gonad-like proximal oviduct and is followed by a ciliated distal oviduct
and a receptaculum seminis. The oviduct is separated from the receptaculum by a valve and a
caecum protrudes from the receptaculum near the valve. The receptaculum seminis comes into
contact with the anterior part of the two associated glands and extends posteriorly to fuse with
their common duct. lts epithelium is columnar cells which change when in contact with sperma-
tozoa. The albumen gland and the capsule gland are side by side. Their ducts are closed
posteriorly and, anteriorly, discharge to the mantle cavity by way of the vagina and egg-laying
duct respectively. Their ciliated epithelium is underlaid by bundles of gland cells. The ducts have
ciliated gutters where egg-capsules and egg-strings are elaborated. A branched bursa copulatrix
is connected to the vagina. The female genital system has several anatomical and histological
characters similar to Pterotrachea.

Spermatogenesis is characterized by “nurse-cells” according to Reinke's (1912) meaning;
spermatozoa attach to them in the seminal vesicle only. The male reproductive system resem-
bles that of the other mesogastropods except that the prostate gland is within the visceral hump.
The prostate is made of many tubules branching from a single lumen. The vas deferens traverses
the prostate ventrally and opens to the mantle cavity.

MALACOLOGIA, 1979, 19(1): 77-85

FORM AND FUNCTION IN TRISIDOS (BIVALVIA) AND
A COMPARISON WITH OTHER BURROWING ARCOIDS

Michael J. S. Tevesz! and Joseph G. Carter2

ABSTRACT

Trisidos Róding, 1798, is unique among the Arcoida in the marked twisting of the posterior
portions of the shell around the hinge axis. Studies of live T. yongei Iredale, 1939, show that this
twisted shell is adaptive for slow, shallow burrowing and byssal attachment in moderately physi-
cally rigorous sedimentary environments.

Analysis of the functional morphology of Trisidos and other modern arcoids suggests that
arcoid burrowers may have evolved three distinct morphologic strategies as a compromise
between burrowing efficiency and minimal resistance to ventilating currents at the shell margins
and within the mantle cavity. Inflated shells with projecting umbos (e.g., Anadara and Noetia)
allow for spacious lateral mantle cavities but offer minimal shell streamlining. Laterally com-
pressed and subcircular shells (e.g., Limopsis and Glycymeris) are moderately streamlined and
offer a wide margin for ventilating currents. The third morphologic strategy, represented only by
Trisidos, combines streamlining of the shell anterior with posterior twisting, which again permits
more efficient ventilation of the mantle cavity. Another adaptive advantage is conferred by this
twisting and also by the anteroposteriorly compressed form of other burrowing arcoids. These
features allow the slow-burrowing animals to more quickly achieve a “low-profile” life position
and thus avoid adverse effects of current scour.

While preventing extreme specialization, the morphological limitations of arcoids have tended
to preserve their evolutionary potential to make repeated transitions from infaunal to epifaunal
life habits and back. The versatility of the pedal-byssal apparatus has probably played a role in
this respect.

Data concerning hinge dentition and shell morphology suggest that Trisidos evolved from a
morphologically less specialized representative of the Arcinae similar to the modern Barbatia.
Barbatia was preadapted for the evolution of a shallow burrowing life habit because of its
relatively efficient ligament and streamlined shape, features initially evolved as adaptations for

epifaunal nestling.
INTRODUCTION

The bivalve order Arcoida is an ancient
group within the subclass Pteriomorphia,
whose fossil record dates back to early
Paleozoic time. Arcoids are generally charac-
terized by ecological conservatism, as evi-
denced by their never having evolved ce-
menting, swimming, or even deeply burrowing
forms. On the other hand, their numerous fos-
sil and Recent species represent a number of
distinct adaptations for “primitive” shallow
burrowing, epifaunal or semi-infaunal nest-
ling, and, in one instance (Litharca), hard
substratum boring.

Perhaps none of the morphological adapta-
tions developed by the Arcoida is more un-
usual and striking than the posterior shell
twisting in the genus Trisidos Róding, 1798. п
some species of Trisidos the posterior com-
missure plane has rotated in the course of
evolution almost 90° relative to the shell ante-

rior (Fig. 1). Despite the uniqueness of this
shell form, its functional significance has
not been fully analyzed.

In this paper we provide ecological obser-
vations on one of the more highly twisted of
the Trisidos species (T. yongei Iredale, 1939)
from Queensland, Australia, and using this in-
formation, attempt to interpret the evolution of
this genus from a functional point of view.
These observations of Trisidos and other bur-
rowing arcoids provide new insights into the
conservative nature of adaptive radiation
within the ancient order Arcoida.

MATERIALS AND METHODS

Live T. yongei was dredged at depths of
2-4 m below the mean tidal level off the lee-
ward (western) side of Magnetic Island,
Queensland, Australia, in April of 1973.
Magnetic Island lies within the Indo-Polynesi-
an Province as delimited by Briggs (1974),

1Department of Geological Sciences, The Cleveland State University, Cleveland, Ohio 44115, U.S.A.
2Department of Geology, University of North Carolina, Chapel Hill, North Carolina 27514, U.S.A.

78 TEVESZ AND CARTER

and is situated between the Australian main-
land and the Great Barrier Reef. The life hab-
its of four individuals of T. yongei were ob-
served on their native substratum. Ciliary cur-
rent patterns and particle transport were ob-
served by removing one shell valve and the
corresponding mantle lobe, and then by intro-
ducing carmine or carborundum particles into
the mantle cavity. Soft parts were studied
from dissections of fresh material.
Additional data on shell form and habitat for
other arcoids were obtained from a variety of
literature sources, and from the collections at
the Yale Peabody Museum (New Haven,
Conn.), the National Museum of Natural His-
tory (Washington, D.C.), and the American
Museum of Natural History (New York).

COMPARATIVE ANATOMY AND
LIFE HABITS

Shell form

Although all fossil and Recent species of
Trisidos are characterized by posterior shell
twisting, this feature is particularly empha-
sized in the Australian species T. yongei. Es-
pecially striking here is the angularity of the
posterior margin, which is set off from the
more anterior parts of the shell by an umbonal
to posteroventral angular deflection (Figs. 1
and 3a). In fossil species of Trisidos, e.g., T.
fajumensis (Oppenheim, 1906), Eocene,
Egypt; T. yatsuoensis Fujii, 1961, Miocene,
Japan; T. prototortuosum Noetling, 1901,
Tertiary, India), and in the Recent 7. tortuosa
(Linné, 1758), Indo-Pacific, the posterior
twisting and angularity are less pronounced.
As is evident from the localities listed here,
modern and fossil Trisidos are restricted to
the Indo-Pacific Region. Only one species, T.
tortuosa, is represented by both Recent and
fossil material (e.g., Tertiary of Mozambique,
Moura, 1969).

Aside from its posterior twisting, T. уопде!
and other species of this genus are typically
arcid in their shell form and hinge dentition.

Soft parts

The soft parts of 7. yongei likewise resem-
ble those of other modern arcids except for
minor differences directly related to posterior
twisting. For example, the left and right valve
adductor muscle attachment scars in T.
yongei are about equal in size, but only the
left one is subquadrate in shape. Also corre-
lated with twisting is an unusual elongation of
the attachment surface of the left-valve pos-
terior pedal retractor muscle.

These observations differ slightly from
those by Ghosh (1924) for T. tortuosa. In this
species, the left-valve adductor muscle at-
tachment scar is triangular and smaller than in
the right valve. Ghosh (1924) also noted that
abdominal sense organs are absent in T.
tortuosa and that esophagus and stomach are
distinct. However, these two latter observa-
tions were subsequently contradicted by
Heath (1941). Additionally, Heath mentions
the following four general differences be-
tween Trisidos and most other arcoids: 1) the
right abdominal sense organ is larger than the
left; 2) the esophagus and stomach are diffi-
cult to distinguish; 3) the alimentary canal
penetrates the heart; and 4) the labial palps
show large, undulating folds in addition to the
more typically arcoid smaller ridges.

In conclusion, except for the labial palp and
alimentary canal features, most of the distin-
guishing anatomical features of Trisidos can
be directly related to its evolution of shell
twisting and the resulting inequivalve condi-
tion.

Mantle cavity currents and particle sorting

As in many burrowing arcoids, water for
respiration and feeding enters the mantle
cavity at the posteroventral shell margin
through apertures formed by the local and
temporary appression of the mantle lobes.
This appression also defines a posterodorsal
aperture for the exhalant current. Particles
trapped by the gills are sorted, and either re-
jected by a posteriorly-directed gill ciliary
tract, or accepted for further sorting and in-
gestion by anteriorly-directed ciliary feeding
tracts. Particle rejection tracts are located on
the mantle and foot as well as on the gills.
These ciliary feeding and rejection tracts do
not differ appreciably from the common arcoid
pattern as developed in Arca and Glycymeris
(Atkins, 1936), Anadara (Lim, 1966), Noetia
and Barbatia (Tevesz, personal observa-
tions), Limopsis, and to some extent, Philo-
brya and Lissarca (Tevesz, 1977). Rejected
particles are removed from the mantle cavity
by being bound in mucus strings and ejected
through the inhalant aperture by sudden valve
contraction.

Life habits

Specimens of 7. yongei were found living in
a muddy, fine to medium sand substratum
containing abundant fragmental shell materi-
al. The environment where the collections
were made was subject to the effects of tidal
currents and wave activity. Nevertheless, the

ARCOID FORM AND FUNCTION 79

area was protected on one side by the nearby
mainland and on the other side by Magnetic
Island and the more distant Great Barrier
Reef, so the general environment in which 7.
yongei lived is properly termed moderately
physically rigorous. This is somewhat similar
to the environment inhabited by 7. tortuosa
(Ghosh, 1924). Ghosh cited a note from the
Director of the Biological Station at Ennor
(Madras, India) indicating that 7. tortuosa “is
fairly numerous in certain parts of Palk Bay
between 4!2 to 6/2 fathom lines on a bottom
of dirty muddy sand, and is not found in crev-
ices.” This information is important, since it
confirms our observation that Trisidos, un-
like other representatives of its subfamily
Arcinae, is typically a burrower (rather than a
nestler or rock-borer).

Specimens of T. yongei left in a laboratory
tank on their native substratum for several
hours showed an integrated burrowing activity
consisting of the following sequence: 1. The
foot emerges anteroventrally, probes the sub-
stratum, and anchors itself in the sediment. 2.
Although initially lying with the anterior com-
missure plane more or less horizontal, 7.
yongei assumes a vertical orientation of this
commissure plane as the anterior of the shell
penetrates the substratum. Because the shell
posterior is torted approximately 90° relative
to the anterior, its posterior commissure plane
therefore assumes a more or less horizontal
position relative to the sediment-water inter-
face. 3. A slow sequence of extension, ex-
pansion, and contraction of the foot pulls the
shell diagonally downward into the substra-
tum until the shell is shallowly buried with only
the shell posterior exposed. The posterior
commissure is then horizontal to and only a
few millimeters above the sediment-water in-
terface. Sequential positions of the shell dur-
ing this burrowing sequence are illustrated in
ЕЮ. 1:

Once the animal is sufficiently buried in the
substratum, it attaches to larger sediment par-
ticles (especially shell debris) by means of an
exceptionally long byssus. The byssus fibers
may attain a length of up to one half the length
of the shell. This burrowing sequence may
take several hours to complete, since it is
commonly interrupted.

Because of the valve inequality and the
horizontal position of the posterior shell mar-
gins, the longer, uppermost left valve forms a
slightly projecting shelf above the shorter
right valve. In terms of its semi-infaunal life
habit, Trisidos is unique among modern rep-

resentatives of the subfamily Arcinae. Other
modern members of this subfamily are either
epibyssate (Arca and Barbatia) or endolithic
(Litharca: Frizzell, 1946). According to
Thomas (1978), some fossil species of Bar-
batia were endobyssate.

MORPHOLOGICAL COMPARISONS WITH
OTHER ARCOIDA

A number of arcoids are known to be bur-
rowers or are inferred burrowers on the basis
of their shell form. These include the modern
Limopsidae and Glycymerididae (Limopsa-
cea), certain Noetiidae and Anadariinae
(Arcacea), and the largely fossil Cucullaeidae
(Arcacea) (Stanley, 1970; Tevesz, 1977; per-
sonal observations). The family Cucullaeidae
is represented by a single surviving genus,
Cucullaea, which is almost certainly a shallow
burrower, but whose life habits are otherwise
little Known. The presumed ancestral arcoid
superfamily Cyrtodontacea and some Paral-
lelondontidae (early Arcacea) are likewise
inferred to have been burrowers (Pojeta,
1971; Stanley, 1972).

Modern arcoid burrowers naturally com-
prise three morphologic groups defined by
lateral compression and umbonal projection.
Group | burrowers show laterally inflated
shells with strongly projecting umbos, as in
Anadara and Noetia (Fig. 2a). Group II bur-
rowers are laterally compressed, dorso-
ventrally expanded, and show relatively sub-
dued umbos, as in Limopsis and Glycymeris
(Fig. 2b). Group Ш burrowers are morphologi-
cally similar to the epifaunal nestler Barbatia
and are intermediate in terms of lateral com-
pression (in the shell anterior) and umbonal
projection. Group Ш burrowers are represent-
ed only by Trisidos.

An interesting aspect of the form of these
modern burrowing arcoids is that none of
them have evolved a streamlined morphol-
ogy, i.e., a form that is at the same time both
laterally and dorsoventrally compressed. This
is unusual because a streamlined form en-
hances burrowing efficiency (Stanley, 1970)
and thus might confer survival-related advan-
tages to these burrowing arcoids.

This lack of streamlining further documents
observations made by Thomas (1976) regard-
ing the morphological and ecological limita-
tions of arcoids. Thomas cogently argued that
the weak duplivincular ligament of most
arcoids is a major cause of this conservatism.

80 TEVESZ AND CARTER

FIG. 1. Sequential shell orientations of live Trisidos yongei during burrowing. A-D = side view; Aı-Dı =
corresponding top view; A,A, = prior to burrowing; B,B, = burrowing; C,Cı = burrowing; D,D: = usual life
position.

ARCOID FORM AND FUNCTION 81

NT ES De
И ЕО Зее
Мей me

on PRE SR be oar
g AA, UN EN
A Ree ITS 5
SY, ..
en Aut et: D
nan er -
N ‘ RT ut = :

FIG. 2. Genera representing two morphologic groups of burrowing arcoids. Exterior and interior views of left
valves and dorsal views of articulated valves for: A) Anadara (Group I); and В) Glycymeris (Group Il).
Respective actual lengths = 57 mm and 24 mm.

82 TEVESZ AND CARTER

LIMITATIONS ON THE EVOLUTION
OF SHELL FORM
IN BURROWING ARCOIDS

Mantle cavity ventilation

We offer the working hypothesis that in ad-
dition to the ligament, factors relating to im-
proving mantle cavity ventilation and minimiz-
ing frictional resistance of water currents with-
in the mantle cavity may have influenced shell
form in burrowing arcoids.

Group | forms typically live with the anterior
portion of the shell buried in the substratum,
so the substratum precludes freedom of circu-
lation of an anteroventral inhalant mantle cur-
rent. This current must therefore be restricted
to the shell posterior, or at least to the poste-
roventral shell margin, thereby increasing fric-
tional resistance at these mantle margins.
Possibly to ease the resultant frictional resist-
ance on the mantle currents, Group | burrow-
ers have inflated their valves and increased
the depth of their umbonal cavity. This signifi-
cantly increases the volume of the lateral
mantle cavities, thereby reducing the frictional
resistance of their circulating water currents.

In contrast, Group Il arcoids have partially
streamlined their shells by increasing their
lateral compression and by reducing the
prominence of their umbos. But lateral com-
pression decreases the volume of the lateral
mantle cavities, thereby increasing frictional
resistance on the interior mantle currents.
Consequently, these species may have re-
tained a non-streamlined sub-circular lateral
profile in order to increase the area of anterior
inhalant and anterior and posterior exhalant
currents (see Atkins, 1936). Because Group Il
burrowers are commonly found in coarser
sediments (such as gravels) than Group | bur-
rowers, they can potentially utilize more of
their mantle margins for mantle cavity ventila-
tion, thereby not only reducing the frictional
resistance of these currents entering the
shell, but also likely promoting circulation
within the mantle cavity.

Trisidos combines features of Group | and
Group Il burrowers. Its twisted form creates а
lateral expansion of the mantle cavity in the
posterior portion of the shell. Moreover, the
posterior margin is expanded and elevated
above the substratum (but at a low angle).
This allows for spacious areas of mantle mar-
gin that are free from the substratum and
which may be utilized for mantle cavity venti-
lation.

As noted previously, the ligamental hypoth-
esis of Thomas (1976) adequately explains
why arcoids have generally been unsuccess-
ful in evolving active burrowers ecologically
comparable to those in certain veneroid su-
perfamilies. But this ligamental hypothesis
fails to explain why arcoids have evolved and
maintained throughout their long evolutionary
history two major morphologic groups among
their burrowing forms, neither of which is
characterized by a totally streamlined shell
form that would minimize, rather than aggra-
vate, the limitation of their weak duplivincular
ligament on burrowing efficiency. Nor does
the ligamental hypothesis account for the fact
that the one burrowing arcoid genus with total
shell streamlining in its anterior, i.e., Trisidos,
has not maintained this streamlined profile in
its posterior. Because of the structure of
duplivincular ligaments, maximum ligament
efficiency is obtained in arcoids with a short
interumbonal distance and, consequently,
with strong lateral compression. Arcoids with
a short interumbonal distance are capable of
maintaining proportionally more ligamental
lamellae attached between the two shell
valves as the ligamental areas separate dur-
ing shell growth. On the basis of considera-
tions of burrowing efficiency, one might ex-
pect that burrowing arcoids would generally
be dorsoventrally compressed for streamlin-
ing and laterally compressed for both stream-
lining and ligament strength, i.e., morphologi-
cally similar to certain epifaunal Barbatia.

This hypothesis makes no assumption re-
garding comparative pumping efficiencies of
arcoid filibranch versus more complex vener-
oid eulamellibranch gills. The ventilation hy-
pothesis assumes only that, in connection
with the anatomy and burrowing habits pecul-
iar to arcoids, relatively free access to mantle
ventilating currents can be adaptively advan-
tageous, and can therefore partially influence
the shell morphology of arcoid burrowers. The
possibility remains that eulamellibranch gills
offer greater potential than filibranch gills for
the evolution of mantle fusion, siphon forma-
tion, and deeper and more streamlined bur-
rowers. But analysis of the evolutionary signif-
icance of gill type between arcoid and vener-
oid bivalves must take into consideration a
wide range of variables, including efficiency of
particle sorting, size and shape of the mantle
cavity and gills, and possibly other factors in
addition to pumping efficiency. Such compari-
sons between the Arcoida and Veneroida are
beyond the scope of the present paper.

ARCOID FORM AND FUNCTION 83

Stability in physically rigorous environments

Inasmuch as burrowing arcoids are typi-
cally limited in their burrowing rate and tend to
occupy current-swept sediments (Thomas,
1975, 1976) their long exposure during rebur-
rowing may be an additional factor influencing
the evolution of posterior twisting in Trisidos
and a highly compressed valve to valve profile
in burrowers such as Glycymeris. Trueman
(1966, 1968a, b) and Trueman et al. (1966)
showed that bivalves with extensive mantle
fusion can build up relatively high water pres-
sures within the mantle cavity. This water, ex-
pelled as jets from the pedal aperture, aids
the foot in burrowing by loosening underlying
sediments. In bivalves lacking an extensively
fused mantle, water jets are not used as effec-
tively, and the burrowing rate is generally
slower. Largely unfused mantle margins
characterize the modern burrowing arcoids,
and arcoids correspondingly require consid-
erable time to assume their final infaunal life
positions (i.e., with the posterior shell margin
protruding only slightly, if at all, above the
sediment surface; Stanley, 1968; 1970;
Tevesz, personal observations). In this con-
text, and especially because Trisidos is a slow
burrower with an elongate shell in physically
rigorous environments, its twisted posterior
may be adaptive for reducing the hazard of
current scour around the shell during burrow-
ing as well as in its normal life position. Simi-

larly, the compressed profile of Glycymeris
results in reducing the exposure of the shell
during burrowing, thereby minimizing current
scour.

EVOLUTION OF TRISIDOS

As shown in Fig. 3, the epifaunal arcoid
Barbatia is morphologically similar to Trisidos
in terms of its lateral compression and mod-
erately projecting umbos. These genera are
likewise similar in their obliquely oriented
hinge teeth, radial external ribbing, and in
some Trisidos species, in their beaded ex-
ternal ornament. Trisidos differs from
Barbatia primarily only in its twisted shell
posterior, the absence of a prominent ventral
gape (compared to some epifaunal Barbatia),
and associated minor changes in internal
anatomy (see above). Since Barbatia has a
long fossil record prior to the Eocene ap-
pearance of Trisidos (Newell: N252-N254, in
Cox et al., 1969), it is reasonable to assume
that it is ancestral to Trisidos.

Epifaunal Barbatia might be considered
preadapted for the evolution of a burrowing
life habit because of its streamlined, wedge-
shaped anterior and relatively subdued
ornament. It may also be preadapted because
its closely spaced umbos make possible a
relatively strong duplivincular ligament
(Thomas, 1976). A strong ligament would be

FIG. 3. Comparative shell features of Trisidos and Barbatia. Exterior and interior views of left valve for: A)
Trisidos yongei \redale. Australia. B) Barbatia novaezelandiae Smith. New Zealand. Respective actual

lengths = 36 mm and 41 mm.

84 TEVESZ AND CARTER

advantageous for pressing the shell valves
against the burrow walls, especially in a spe-
cies lacking fused mantle margins. Unlike the
burrowing arcoids, Barbatia may have been
able to evolve such shell streamlining be-
cause its epifaunal life habit imposes few re-
strictions on the area of its shell margin uti-
lized for ventilating currents. As noted by
Bretsky (1976), Barbatia utilizes its ventral
shell margin for maintaining the inhalant man-
tle current, thereby leaving the entire posterior
shell margin for the exhalant current. Barbatia
is occasionally found nestling in cryptic habi-
tats, but its inhalant area is still generally suf-
ficiently elevated above the substratum to al-
low for free circulation of water currents. The
laterally compressed form of Barbatia is
clearly advantageous in connection with its
habit of nestling in crevices, and its moderate
dorsoventral compression is likewise advan-
tageous for concealing the shell in this eco-
logical setting.

But according to the ventilation hypothesis
elaborated above, the evolution of infaunal
burrowing in an arcoid with the shell morphol-
ogy of Barbatia would be accompanied by
problems of mantle cavity ventilation. Re-
duced ventilation may have resulted in con-
nection with its laterally compressed mantle
cavity when the ventilating currents became
restricted to the posterior shell margins, i.e.,
above the sediment-water interface. In their
evolution of burrowing life habits, the hy-
pothesized descendants of Barbatia might
have solved the mantle ventilation problem by
evolving greater lateral inflation of the valves
and a deeper umbonal cavity (as in Anadara),
or by evolving a rounded lateral profile (as in
Glycymeris). But these two alternatives re-
quire major remodeling of the shell. The
ancestors of Trisidos evidently followed an
evolutionary pathway involving greater
economy of change, i.e. simple twisting in the
shell posterior. This twisting was accom-
plished, as noted above, with minimal change
in internal anatomy and with retention of both
lateral and dorsoventral streamlining in the
shell anterior. While increasing the area of the
posterior shell margin elevated above the
sediment-water interface and while increasing
the internal volume of the posterior mantle
cavity, the posterior twisting in Trisidos also
improved the stability of the shell by creating a
low profile in its living position.

It is interesting to speculate that the hy-
pothesized change from epifaunal nesting to
infaunal burrowing in the evolutionary history

of Trisidos may have greatly influenced the
nature and amount of suspended sediment
entering its mantle cavity. In addition to bring-
ing its inhalant area close to the sediment-
water interface, the unique burrowing habit of
Trisidos caused its inhalant and exhalant cur-
rents to lie in a similar position relative to a
horizontal plane along the sediment surface.
Consequently, these two currents may be
less efficiently separated in Trisidos than in its
hypothesized epifaunal ancestors.

SUMMARY AND CONCLUSIONS

As noted by Thomas (1976), the weak
arcoid ligament has apparently limited evolu-
tionary specialization by arcoids for both deep
burrowing and permanent epibyssate attach-
ment, because it limits valve gape in burrowing
and anterior reduction. It is presently pro-
posed that problems of mantle ventilation and
shell stability in the context of slow burrowing
have additionally imposed restrictions on the
evolution of streamlined shallow burrowers in
this order. But Thomas (1976) also noted that
the inherent limitations on arcoid evolution
have nevertheless permitted arcoids to make
repeated transitions from epifaunal to infaunal
modes of life and back. For example, accord-
ing to Stanley (1972), the early Arcoida dem-
onstrate a general evolutionary trend from
ancestral burrowing to epifaunal life habits.
Within the Arcacea, the Arcidae apparently
evolved at an epifaunal grade of evolution
and later reverted to the infaunal habit in
many species. Later, certain infaunal Arcidae
re-radiated back to the epifaunal habit, e.g., in
the origin of Arcopsis. The infaunal Limopsi-
dae (Limopsacea) likewise radiated into the
epifaunal habit with the origin of the Philo-
bryidae (Tevesz, 1977).

The invasion of a new adaptive zone is
often accompanied by high-level taxonomic
diversification (Simpson, 1953; Valentine,
1973). Arcoids exemplify this trend because
their evolutionary life habit transitions are fre-
quently accompanied by the appearance of
new taxonomic categories, even at the super-
family level (Pojeta, 1971; Tevesz, 1977). In
this respect, the ecologically versatile pedal
apparatus of arcoids may have played a ma-
jor role in their preadaptation for the evolution
of both burrowers and epifaunal species. In
addition to providing a powerful burrowing
organ, it can afford firm byssal attachment in
the epifaunal forms. The versatility of this

ARCOID FORM AND FUNCTION 85

pedal apparatus possibly compensated for
their limitations in ligament strength, thereby
allowing for their evolutionary persistence and
for much of their ecological diversity.

ACKNOWLEDGEMENTS

We thank Drs. Roger D. К. Thomas, 5. M.
Stanley, and four anonymous reviewers for
critically reading the manuscript. The faculty
and staff of the School of Biology, James
Cook University of North Queensland,
Townsville, provided invaluable help and
hospitality that led to successfully obtaining
live material for study. Part of this research
was sponsored by research grants to the
senior and junior authors from the National
Science Foundation, GB-35482 and DEB 77-
00022, respectively.

Illustrations were done by Mr. Michael
Ludwig.

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habits in the Bivalvia (Mollusca). Geological
Society of America Memoir, 125: 296 p.

STANLEY, S. M., 1972, Functional morphology and
evolution of byssally attached bivalve molluscs.
Journal of Paleontology, 46: 165-212.

TEVESZ, M. J. S., 1977, Taxonomy and ecology of
the Philobryidae and Limopsidae (Mollusca:
Pelecypoda). Postilla, 171: 64 p.

THOMAS, R. D. K., 1975, Functional morphology,
ecology and evolutionary conservatism in the
Glycymerididae (Bivalvia). Palaeontology, 18:
217-245.

THOMAS, R. D. K., 1976, Constraints of ligament
growth, form and function on evolution in the
Arcoida (Mollusca: Bivalvia). Paleobiology, 2:
64-83.

THOMAS, R. D. K., 1978, Shell form and the
ecological range of living and extinct Arcoida.
Paleobiology, 4: 181-194.

TRUEMAN, E. R., 1966, Bivalve molluscs: fluid
dynamics of burrowing. Science, 152: 523-525.

TRUEMAN, E. R., 1968a, The burrowing activities
of bivalves. Symposium of the Zoological So-
ciety of London, 22: 167-186.

TRUEMAN, E. R., 1968b, The locomotion of the
freshwater clam Margaritifera margaritifera
(Unionacea: Margaritanidae). Malacologia, 6:
401-410.

TRUEMAN, E. R., BRAND, A. R. & DAVIS, P.,
1966, The dynamics of burrowing of some com-
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VALENTINE, J. W., 1973, Evolutionary paleoecol-
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After this paper was accepted for publication, С. McGhee (Lethaia, 1978, 11: 315-329) published a paper
concerning the theoretical implications of shell twisting in Trisidos and other bivalves. The reader is referred

to this paper for this theoretical treatment.

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CYCLE DE DEVELOPPEMENT, CROISSANCE ET FECONDITE DE CINQ
POPULATIONS DE LYMNAEA CATASCOPIUM CATASCOPIUM
(GASTROPODA, LYMNAEIDAE) AU LAC SAINT-LOUIS, QUEBEC, CANADA!

Bernadette Pinel-Alloul et Etienne Magnin

Département des Sciences Biologiques, Université de Montréal, C.P. 6128,
Montréal, Québec H3C 3JL, Canada

RESUME

En suivant l'évolution de la structure démographique de cinq populations de Lymnaea
catascopium catascopium, le Lymnaeide le plus important au lac Saint-Louis, Québec, nous
avons pu définir son cycle de développement, et évaluer sa croissance et sa fécondité. Cette
espèce présente deux types de développement, l'un simple avec une seule génération par
année et une seule période de reproduction effective (au printemps), l’autre plus complexe avec
deux générations par année et deux périodes de reproduction en juin-juillet puis d'août à
novembre. Ces différences fondamentales dans le cycle de développement peuvent être mises
en relation avec la nature des eaux du lac: les eaux dures et alcalines du fleuve St-Laurent et les
eaux douces et neutres de la rivière des Outaouais. La croissance des individus est de type
sigmoide et présente des variations annuelles intraspécifiques qui s'expliquent plutôt par des
différences dans la nature trophique des milieux que par des variations des composantes
physico-chimiques. L. catascopium catascopium dépose deux types de pontes et est sexuel-
lement mature à une taille inférieure à 10 mm. Sa fécondité estimée sur la période du 18 juin
1970 au 23 novembre 1971 varie de 3380 oeufs à 43674 oeufs selon les populations. Au
laboratoire, chaque spécimen dépose de 273 à 690 oeufs à 15°C et 226 à 365 oeufs à 20°. Les
résultats de notre étude laissent aussi entrevoir des implications évolutives en relation avec la

nature des milieux d’eau douce.

INTRODUCTION

Les Lymnaeidae, comme la plupart des
pulmonés d’eau douce présentent un grand
potentiel de variation à la fois au point de vue
morphologique et au point de vue écologique
(Hubendick, 1951; Hunter, 1961a, b; Walter,
1968, 1969; Hunter, 1972, 1975). Au Canada,
la distribution et l'anatomie des Lymnaeidae
est bien connue (Clarke, 1973) mais aucune
étude ne traite de la dynamique de population
de ces mollusques. C’est ce dernier aspect
que nous avons étudié sur cing populations
de Lymnaea catascopium catascopium Say,
(1817), au lac Saint-Louis, Québec, où les
mollusques benthiques constituent un des
groupements les plus importants de la zone
littorale (Magnin, 1970). Nous étudierons le
cycle de développement, la croissance et la
fécondité de ces populations situées dans
des biotopes aux caractéristiques physico-
chimiques et trophiques différentes.

MILIEU D’ETUDE

Le lac Saint-Louis (45°15’N et 73°40’W) est
un élargissement du fleuve Saint-Laurent

situé au sud de Ме de Montréal. Les stations
échantillonnées peuvent être classées en
trois types correspondant aux trois grandes
masses d'eau du lac déjà décrites par
Brundritt (1963), Pageau & Lévesque (1968)
et Magnin (1970): les stations 3 et 6 situées
dans les eaux vertes et dures du fleuve Saint-
Laurent, les stations 2 et 10 dans les eaux
brunes et douces de la rivière des Outaouais
et la station 9 dans les eaux constituées par
un mélange des deux eaux précédentes. Le
Tableau 1 indique les valeurs moyennes et
extrèmes des paramètres physico-chimiques
de l’eau à chacune des stations d'échantil-
lonnage en 1970 et 1971. Les variations
saisonnières de la température et la durée de
période avec glace sont très semblables dans
les différentes stations (Fig. 1). Les stations
d'échantillonnage présentent aussi des dif-
férences dans les facteurs biotiques du
milieu. Les algues benthiques sont surtout
représentées par les algues vertes fila-
menteuses (Cladophora) dans les stations 3
et 6 du fleuve Saint-Laurent, par les
Diatomées dans les stations 2 et 10 de la
rivière des Outaouais et par les algues bleues

ÎTexte adapté et extrait d'une partie d'une thèse de Ph.D. soutenue au département des Sciences biologiques de l'Université

de Montréal (Pinel-Alloul, 1975).

(87)

88 PINEL-ALLOUL ET MAGNIN

TABLEAU 1. Moyenne annuelle et valeurs extrèmes (entre parenthèses) des paramètres physico-
chimiques des eaux à chaque station d'échantillonnage.

Paramètres Années Sta. 3 Sta. 6 Sta. 2 Sta. 10 Sta. 9

pH 1970 7.9 8.2 Vi 7.0 TT
(7.0-8.5) (7.2-8.8) (6.8-7.9) (6.6-7.7) (7.0-8.6)
1971 8.0 8.3 7.0 7.4 7.9
(7.2-8.7) (7.7-9.1) (5.8-7.7) (6.9-7.9) (7.1-9.1)
О»? dissous mg/l 1970 11 13 10 9 11
(9-14) (10-16) (7-12) (6-10) (9-14)
1971 10 13 9 10 10
(6-14) (8-17) (7-12) (8-11) (9-12)
Alcalinité mg/l 1970 85 78 22 21 27
(64-90) (68-105) (16-30) (10-30) (20-40)
1971 82 79 30 26 43
(68-98) (65-88) (19-42) (18—40) (30-68)
Dureté totale mg/l 1970 105 102 27 29 37
(95-120) (90-120) (20-35) (25-35) (30-55)
1971 104 107 35 32 5%
(85-125) (95-123) (25-55) (25-40) (35-100)
Dureté en calcium mg/l 1970 80 73 20 21 27
(70-90) (60-85) (15-25) (20-55) (20-40)
1971 81 83 24 21 46
(70-100) (75-95) (20-35) (15-30) (30-90)
25

OU
= 20
SIS
5
E Sta 6
= St
— а
Sta. 10
3 15 Sta. 9
о
=
8
à
= 10
Ф
=

м J J A $ O N Hiver M J J A 5 O N

FIG. 1. Variations saisonnières de la température de l'eau aux différentes stations d'échantillonnage en
1970 et 1971.

LYMNAEA CATASCOPIUM CATASCOPIUM 89

dans les eaux mixtes de la station 9. La faune
malacologique présente aussi un aspect dif-
férent dans les différentes stations: les
Bithynies (Prosobranches) prédominent dans
les eaux du fleuve Saint-Laurent et dans les
eaux mixtes tandis que les Lymnées et les
Planorbes (Pulmonés) sont plus abondantes
dans les eaux de la rivière des Outaouais.

MATERIEL ET METHODES

L’échantillonnage fut effectué en 1970 et
1971, des mois de mai à novembre inclusive-
ment, selon la méthode des quadrats (Zhadin,
1954; Heurteaux & Marazanof, 1965; Mara-
zanof, 1969; Finnish IBP-PM Group, 1969;
Houp, 1970). Tous les quinze jours, nous
fixions dans chacune des stations quatre
quadrats d'un mètre carré d'où nous retirions
avec précaution toutes les roches mobiles.
Hors de l'eau, nous detachions tous les mol-
lusques et pontes qui y adhéraient et les
roches étaient ensuite lavées et nettoyées
dans un seau d’eau afin de recueillir les plus
petits spécimens. Finalement nous prélévions
manuellement les mollusques présents sur le
fond de chaque quadrat et sur les roches im-
mobilisées dans la vase. Si l’on tient compte
de la surface totale des roches, la surface
échantillonnée est supérieure à un mètre
carré et elle varie en fonction de la grandeur
des roches. Diverses techniques d'estimation
des surfaces recouvertes de roches ont déjà
été décrites (Hunter, 1953; Calow, 1972).
Mais comme l'indique Hunter (1961a), l'esti-
mation des abondances par surface fixe de
substrat, quelle que soit sa nature, est justi-
fiée si l’on analyse les résultats sur une base
comparative, ce que nous nous proposons de
faire précisément.

Au laboratoire, les mollusques et les pontes
récoltées étaient fixés à l'alcool а 70% addi-
tionné de glycerine, triés, comptés et
mesurés (distance de Гарех de la coquille au
bord distal du péristome) aux grossissements
6X et 12X d'une loupe binoculaire munie
d'une chambre claire. L'analyse de la struc-
ture des populations a été faite selon la
méthode déjà décrite par Pinel-Alloul &
Magnin (1971).

La taille à la maturité sexuelle fut estimée
par la taille moyenne des individus au début de
leur période de reproduction. La fécondité
des Lymnées de chaque population fut
estimée par la formule:

XK

N; x O;

(1) F= Y
=

dans laquelle N; est le nombre de pontes
récoltées et О; le nombre moyen d'oeufs par
ponte à chaque date d’échantillonnage i, k
étant le nombre d’échantillonnages effectuées
au cours de la période de reproduction. Nous
avons aussi estimé au laboratoire la fécondité
des Lymnées des populations des stations 2,
6 et 9, représentant chacune un des types de
biotope du lac. Les élevages ont été faits aux
températures de 15°C et 20°C sous une
photopériode: 12-12.

RÉSULTATS

Cycle de développement et structure
des populations

Au lac Saint-Louis, Lymnaea catascopium
catascopium présente deux types de cycle de
développement: un type simple avec une
seule génération par année aux stations 3, 6
et 9 (Fig. 2) et un type plus complexe avec
deux générations par année aux stations 2 et
1ON(Fig 3):

En suivant les variations de la structure en
taille des populations des stations 3, 6 et 9
(Fig. 2), nous constatons que la distribution
des spécimens est bimodale en juin et juillet
1970 et 1971, ce qui témoigne de la coexist-
ence de deux cohortes á cette période de
l'année. Les représentants de la cohorte de
1969 constituent la totalité de la population à
la fin mai 1970 puis disparaissent à la fin juin
(station 9) ou au début juillet (stations 3 et 6)
aprés avoir donné naissance á une nouvelle
génération (cohorte 1970). Au printemps
1971, le même phénomène se reproduit, la
cohorte 1970 engendrant la nouvelle généra-
tion de 1971; nous remarquons cependant
que les individus de la cohorte 1970 survivent
plus longtemps que ceux de la cohorte 1969
aux stations 3 et 6.

En plus d'indiquer les effectifs de chaque
échantillon (N), la Figure 2 rapporte aussi les
nombres de pontes récoltées (n) à chaque
date d’échantillonnage. Exception faite en
1971 a la station 6, il se succéde deux péri-
odes de ponte chaque année, mais, seule la
période de ponte printanniére coincide avec
l'apparition d'une nouvelle génération. La
période de ponte estivale n’est suivie que de
l'apparition de quelques individus. Les pontes
printannières de 1970 et 1971 sont déposées
par les individus des cohortes 1969 et 1970
qui ont survécu durant l'hiver; les pontes
récoltées en août, septembre et octobre sont
probablement produites par certains individus

90 PINEL-ALLOUL ET MAGNIN

=m 20 STATION 3
n: 34 25 4

30

peers. ++ 117
iene ent

w
x o cohorte 1971
u N 3 ne 63 155 93 60 80 49 209 30
= 1971
5 Е ет T
= 27 7 22 5 1902 16: 30213727 122025 8
> МА! JUIN JUILLET AQUT SEPTEMBRE OCTOBRE NOVEMBRE
á
< 30
2 п : 2 1 9 1
2 cohorte 1969 ?
10 mar {! }
er 2 cohorte 1970
o О
rh 34 58 10 19 67 42 75 n3 77 29 67
1970
ar T Ti EST T ni T T ru A y
28011 23 6 23 5 18 1 17 20 1277126 9
Mal JUIN JUILLET AOÛT SEPTEMBRE OCTOBRE NOVEMBRE
STATION 6
== |
30
107 421 31
1
20 N | | cohorte 1920
sn": | pet p + a A
e o == —— nn 9,
= N vn 128 603 591 422 218 235 234 159 220 87 210 80 209 1971
= Al ol = Г e sl e a ele el
= 259,7, 21 5 276 3003 ¿27% 12253282023
2 MA! JUIN JUILLET AOUT SEPTEMBRE OCTOBRE NOVEMBRE
< 30
x
2 57 39 3 36 1
>
2 2
10 =$ ; + H | ott ++ # à ?
о
м 4 = 29 76 129 320 222 209 325 355 364 143 247 105 150 158
== me mm T T T <
75 ¿2 28 п 18 23 6 23 55. № 1 17 30 12 26 9
MAI JUIN UILLET AOUT SEPTEMBRE IC TOBRE NOVEMBRE
STATION 9
=~.
23 » LL] 7 IL]
зо |
20 —| | ‘ } |
| |

x Du
$ 261 230 275 273 33° 25)
= 1971
= T T T Saal
5 13 28 12 25 8 22
> SEPTEMBRE IC TOBRE NOVEMBRE
6

LONGUEUR

19%
273 203 203 a » 1970
yr

2) 5 23 7 22 4 18 1 14 30 n 26 9

MA IUIN JUILLET aout SEPTEMBRE OCTOBRE NOVEMBRE

FIG. 2. Structure en taille des populations de L. catascopium catascopium aux stations 3, 6 et 9. N: effectif
des échantillons; n: nombre de pontes.

LONGUEUR EN MILLIMETRES

LONGUEUR EN MILLIMETRES

LYMNAEA CATASCOPIUM CATASCOPIUM 91

STATION 2

30
192 186 47 53 5 9 16 8 1
cohorte 1971 I

n 86 133 154 4 9

20

о

90

10
E $ :
= u cohorte 1971 0
lo)
59 203 196
1971
28 8 22 6 22 2 17 31 14 28 12 26 9 22
MAI JUIN JUILLET AOUT SEPTEMTRE OCTOBRE NOVEMBRE
30
m: 10 8 12 52 12 33
20 cohorte 1969 E nr
) a 4 ++
1 7 : cor te 19701
1 A er LE
о | 2 | en
TES y à ij re $. te 19700
о
158 187 82 242 267 174 27
1970
18 7 22 3 17 31 14 28 15 28 11
JUIN JUILLET AOÛT SEPTEMBRE OCTOBRE NOVEMBRE
STATION 10
= 20
30
n 41 41 32 7 12 54 54 6 4
cohorte 1971 I
cohorte 1970 E !
20
| | i |
10 | See Rs
4 AGS | |
E 1 cohorte 1971 2
9 306

255 196 208 315 285 412 273 190

1971

22 6 20 3 17 31 14 28 12 26 9 23
MA! JUIN JUILLET AOÛT SEPTEMBRE OCTOBRE NOVEMBRE
30
п + 2 20 zZ
75 cohorte 70 1

N
о

НН!

à А
tit bees ea

114

1970

21 5 18 7 22 3 17 31 14 28 15 28 n
SEPTEMBRE OCTOBRE NOVEMBRE

MAI JUIN SUE BET AOUT

FIG. 3. Structure en taille des populations de L. catascopium catascopium aux stations 2 et 10. N: effectif
des échantillons; n: nombre de pontes.

92 PINEL-ALLOUL ET MAGNIN

des cohortes 1970 et 1971, nés au printemps
de la même année et qui ont atteint leur ma-
turité sexuelle.

La Figure 3 illustre la structure des popula-
tions des stations 2 et 10 qui ont un cycle de
développement à deux générations par
année. A chaque date d’échantillonnage, la
distribution en taille des spécimens est
généralement bimodale. La première généra-
tion (Il) est engendrée par les survivants des
cohortes de l’année précédente et apparaît
en juin ou juillet (le 8 juin 1971 et le 18 juin
1970 à la station 2; le 22 juin 1971 et le 7
juillet 1970 à la station 10). La deuxième
generation (Il) est engendrée par les individus
matures de la génération printannière as-
sociés à quelques survivants des cohortes de
l'année précédente et apparaît durant tout
l'été et l'automne, depuis le mois d'août
jusqu'au mois de novembre. La generation
printannière (I) coexiste avec la generation
estivale (Il) jusqu’à l'hiver et même parfois
jusqu'au printemps suivant (station 10, prin-
temps 1970).

CE ee SA af,
= = = STA
@-----@ SIA9
= o----0 STAIO
/
vi
Zz /
ud 20 ‘
hn 2
i ,
PA
à »
ud u
E О
= Cohorte в.
15 a
> 1969 :
O 7
= „2
ER
d
d
œ С '
5 10 '
Ww A
= E
O '
“a „р
O ‘
= d

МА! JUIN JUIL AOÛT SEPT oct

1970

A la station 2, nous avons récolté des
pontes à chaque date d'échantillonnage (п
dans la Figure 3). Nous pouvons discerner
deux pics de pontes, correspondant chacun
avec l'apparition d'une nouvelle génération.
La ponte printannière déposée en mai et juin
par les individus des cohortes de l'année
précédente est très nette en 1971 mais l'est
beaucoup moins en 1970, la période
d'échantillonnage ayant débuté plus tard. La
ponte d'été-automne déposée par les indi-
vidus de la génération printanniere (I) très
intense en août est de plus en plus faible
jusqu'en novembre. A la station 10, les deux
périodes de pontes sont bien définies en
1971; toutefois, la ponte d'été-automne пе se
poursuit pas jusqu'en novembre et les deux
périodes de pontes ne se chevauchent pas
comme à la station 2.

Croissance des individus des
différentes cohortes

Les courbes de croissance des générations
| des cohortes de 1970 et 1971 (Fig. 4) sont

Cohorte
19701.”

® e . CE
2 / a aoe us
9 12 Be s
A 4 o g ,® .
y à s

. 19700 eS

En Cohorte 1971 П

SEPT ОСТ NOV

AOÛT

NOV МА! JUIN JUIL

1971

DATES DE PRÉLÈVEMENT

FIG. 4. Croissance en longueur des L. catascopium catascopium des différentes cohortes à chaque station
d'échantillonnage en 1970 et 1971.

LYMNAEA CATASCOPIUM CATASCOPIUM 93

de type sigmoïde caractérisé par une phase
de croissance rapide (juin à la fin août) suivie
d'une phase de croissance lente (septembre
à novembre); à la mi-août, soit deux mois
après leur naissance les individus des
générations printannieres (Il) de 1970 ont еп
effet déjà effectué 80% de leur croissance à la
station 2 et environ 70% de leur croissance
aux stations 3, 6, 9 et 10. Il leur faut ensuite
de 2 mois (stations 2 et 10) à 10 mois (stations
3, 6 et 9, incluant la période d’hibernation)
pour effectuer le reste de leur croissance.
Signalons aussi que la brusque diminution de
croissance à la mi-août coincide avec le
commencement de la ponte d’été-automne,
période à laquelle certains individus nés au
printemps ont atteint la taille de la maturité
sexuelle. Une analyse de variance et un test
de Student indiquent que les tailles moyennes
atteintes en septembre par les générations
printanières des stations 2, 6 et 10 ne sont
pas significativement différentes en 1970 et
1971 (< = 0.05). A la station 3, par contre, les
individus sont significativement plus grands
en 1971 (18.4 mm) qu’en 1970 (15.9 mm) eta
la station 9, ils sont significativement plus
petits en 1971 (13.2mm) qu’en 1970
(15.9 mm) (@ = 0.01). Les mêmes tests
montrent qu'en septembre 1970, il пу a pas
de différence significative de tailles chez les
individus des stations 2, 3, 9 et 10 (a = 0.05).
Par contre, en septembre 1971 les tailles at-
teintes dans les différentes stations sont
toutes significativement différentes, se clas-
sant ainsi par ordre décroissant: stations 3,
10, 2,9 et 6.

Les courbes de croissance des individus
des cohortes d'été-automne (Il) des stations 2
et 10 sont plus difficiles à interpréter (Fig. 4).
Durant les premiers mois de leur existence,
les lymnées grandissent mais ce phénomène
n'est pas mis en évidence par la variation de
leur longueur moyenne, cette moyenne étant
constamment diminuée par l'apparition de
nouvelles recrues dans la population. Nous
pouvons cependant constater que le tiers de
la croissance de ces individus s'effectue
avant la période d’hibernation (26% à la sta-
tion 2, 34% à la station 10) et que les deux
autres tiers s'effectuent au printemps suivant
sur une période de deux mois environ.

Les comparaisons entre les tailles
moyennes atteintes en septembre et celles
atteintes au printemps suivant indiquent que
les individus des cohortes printanieres (I)
n'effectuent aucune croissance hivernale
mais que ceux des cohortes d’été-automne

(II) continuent à grandir durant l'hiver (a =
0.01).

Reproduction et fécondité

La taille à la maturité sexuelle, estimée par
la taille moyenne des individus de chaque
cohorte au début de leurs périodes de pontes
(mai-juin; août-septembre) varie entre 6.9 mm
(station 10, cohorte 1970 Il, le 28 mai 1971) et
17.8 mm (station 3, cohorte 1970 |, 7 juin
1971) (Tableau 2). Au laboratoire, nous
avons noté que le plus petit spécimen ayant
déposé des pontes provenait de la station 2 et
mesurait 8.15 mm. Il semble donc que les L.
catascopium catascopium du lac Saint-Louis
puissent atteindre la maturité sexuelle à une
taille inférieure à 10 mm. Nos resultats indi-
quent aussi que les individus des populations
à cycle de développement simple (station 3, 6
et 9) atteignent généralement la maturité
sexuelle à une plus grande taille que ceux
des populations à cycle de développement
plus complexe avec deux générations par
année (stations 2 et 10).

La densité des pontes des lymnées (nb/m?)
varie au cours de la saison (Fig. 5). Les
pontes déposées entre août et novembre
1970 proviennent des individus des généra-
tions printaniéres de l’année et elles sont les
plus nombreuses aux stations 2 et 9 (environ
10 par mètre carré). Les pontes déposées en
juin et durant la premiée quinzaine de juillet
de 1971 proviennent des individus de la
génération d'été-automne de 1970 aux sta-
tions 2 et 10 et des survivants de la généra-
tion printaniére de 1970 aux stations 3, 6 et 9.
Le nombre de pontes printaniéres est trés fort
aux Stations 2 et 6 (respectivement 64 et 80 au
m? les 8 et 22 juin 1971). Le second pic de
ponte en 1971 (août-septembre) est très
réduit ou inexistant aux stations 3, 6 et 9, mais
il est, par contre, plus important aux stations 2
et 10 ou il représente alors la principale et
unique période de pontes des individus nés
au printemps.

L. catascopium catascopium produit deux
types de pontes: la plupart, dites typiques,
sont longues et étroites (12 mm et plus de
longueur sur 2 a3 mm de largeur) et en forme
de croissant; les autres plus rares, dites
atypiques, sont rondes ou légèrement
ovoides et de petites dimensions (2 à 3 mm
de longueur sur 2 mm de largeur). Ces pontes
peuvent contenir de 5 à 175 oeufs. En
moyenne, une ponte de L. catascopium
catascopium contient 44 oeufs à la station 2,

94 PINEL-ALLOUL ET MAGNIN

TABLEAU 2. Tailles à maturité sexuelle des L catascopium catascopium, estimés par
longueur moyenne des individus de chaque cohorte au début de leurs périodes de reproduction.

Station Cohorte Date
1969 Il 18 juin 1970
1970 | 3 août 1970
2 1970 Il 28 mai 1971
1971 | 2 août 1971
1969 | 23 juin 1970
1970 | 1 sept. 1970
3 1970 | 7 juin 1971
1971 | 13 sept. 1971
1969 | 28 mai 1970
6 1970 | 1 sept. 1970
1970 | 25 mai 1971
1969 | 21 mai 1970
9 1970 | 4 aout 1970
1970 | 22 juin 1971
1971 | 15 août 1971
1969 | et Il 7 juil. 1970
10 1970 | 3 août 1970
1970 Il 28 mai 1971
1971 | 3 aout 1971

12.59 + 2.14
12.13 + 0.55

6.97 + 0.89
11.02 + 0.29

17.12 + 1.46
15.19 + 0.85
17.84 + 2.26
18.65 + 0.72

13.24 + 0.91
11.30 + 0.13
13.08 + 0.62

11.40 + 0.41
13.87 + 0.34
17.50 + 1.62
11.70 + 0.26

1311070
10.07*
6.86 + 1.09
11.55 + 0.24

la

Taille moyenne (mm) + erreur standard

“un seul spécimen.

TABLEAU 3. Fécondité des L. catascopium catascopium des cohortes de chaque population en 1970 et

1971.
Station Cohortes Période de reproduction Nombre d'oeufs déposés
1969 Il 18 juin—7 juil. 1970 490
2 1970 | 22 juil.—11 nov. 1970 4874
1970 Il 28 mai—7 juil. 1971 13827
19711 22 juil—23 nov. 1971 24483
Total: 43674
1969 | 18 juin—7 juil. 1970 151
31 août—15 oct. 1970 262
3 19701 { 28 mai—18 juin 1971 2946
19711 14 sept. 1971 21
Total: 3380
1969 | 28 mai—18 juin 1970 3294
31 août—14 sept. 1970 423
y too! 28 mai—18 juin 1971 24240
19711 — -
Total: 27957
1969 | 28 mai—6 juin 1970 5046
5 aoüt—14 sept. 1970 3558
- 1370, 6 juin—7 juil. 1971 7815
19711 17 août—31 août 1971 1038
Total: 17457
1969 Il 7 juil. 1970 94
10 1970 | 31 août—14 sept. 1970 1435
1970 Il 28 mai—7 juil. 1971 5426
19711 5 août—28 sept. 1971 4468

Total:

11423

LYMNAEA CATASCOPIUM CATASCOPIUM 95

50
0 Ten STA.10

50

50
0 STA.9

50

50
STA.6

See. e

NOMBRE DE PONTES PAR METRE CARRE
©

50

A S O N
1970

J J A S O
1971

FIG. 5. Variation de la densité (nb/m?) des pontes de L. catascopium catascoium d'aoút á novembre 1970 et
de juin á octobre 1971 dans chaque station d'échantillonnage.

43 oeufs à la station 3, 37 oeufs à la station 6,
49 oeufs á la station 9 et 38 oeufs á la station
10. Au laboratoire les pontes déposées par
les Lymnées contenaient de 5 à 100 oeufs;
les nombres moyen d'oeufs par ponte étaient
de 29 (15°C) et 24 (20°C) pour les Lymnées
de la stations 2; de 20 (15°C) et 25 (20°C)
pour celles de la station 6 et de 69 (15°C)
pour celles de la station 9.

La variation du nombre d'oeufs par ponte

est tres forte dans toutes les populations; ceci
suggère que cette valeur n'est pas un critère
de la fécondité des organismes et que celle-ci
serait plutót estimée par le nombre total
d'oeufs déposés. Compte tenu de ces
critères, nous avons estimé la fécondité des
individus de chaque génération, à chaque
année et dans chacune des populations par
le nombre total d'oeufs déposés sur 4 m? au
cours de la ou des périodes de reproduction

96 PINEL-ALLOUL ET MAGNIN

de chaque génération, connaissant la durée
de la période de reproduction, le nombre de
pontes et le nombre moyen d'oeufs par ponte
à chaque date d’échantillonnage. Les
résultats (Tableau 3) indiquent que la fécon-
dité des populations de Lymnées diffèrent
d'une année à l’autre et d'une station à
l’autre. Un plus grand nombre de pontes a été
récolté en 1971; ceci est probablement dû au
fait que nous avons eu, en 1970, une plus
grande difficulté à repérer les pontes sur les
roches. Parmi les populations qui ont un cycle
avec deux générations per année, celle de la
station 2 est plus féconde que celle de la
station 10. Parmi les populations qui ne pro-
duisent qu'une seule generation par année, si
nous comparons seulement les résultats ob-
tenus pour la génération printanière (1) de la
cohorte de 1970 dont nous avons observé les
deux périodes de pontes, ce sont les individus
de la station 6 qui sont les plus féconds
(24663 oeufs); viennent ensuite ceux de la
station 9 (11373 oeufs) et finalement ceux de
la station 3 qui sont très peu féconds (3208
oeufs).

Au laboratoire, la fécondité des L. catas-
copium catascopium varie de 273 à 690
oeufs par individu à 15°C et de 226 à 365
oeufs par individu à 20°C. Ces données sont
basées sur toute la période de vie des organ-
ismes, celle-ci variant de 48 à 150 jours selon
les individus. Seuls les résultats obtenus chez
les individus en provenance de la station 6
permettraient de supposer que la fécondité
des individus est plus forte à 20°C (365 oeufs
par spécimen) qu'à 15°C (273 oeufs par spéci-
men). À partir des résultats obtenus au
laboratoire, nous avons estimé la relation
entre la fécondité et la taille des organismes
d'une part et celle entre la fécondité et le
nombre d'oeufs moyen par ponte. ll en ressort
que la fécondité des organismes n'est pas
plus forte chez les gros spécimens que chez
les plus petits (r = 0.266; a = 0.05) et que le
nombre moyen d'oeufs par роще n'est pas
plus faible chez un spécimen qui dépose
beaucoup de pontes que chez un autre qui en
dépose peu (r = —0.158; a = 0.05).

DISCUSSION

Les variations de températures entre les
milieux ne peuvent induire les différences
fondamentales observées dans le cycle de
développement des Lymnées car, comme
nous l'avons vu, elles sont très faibles. Il
semble, par contre, que Гоп puisse mettre en

corrélation la nature chimique des eaux et le
type de cycle annuel des Lymnées: les popu-
lations qui présentent un cycle de dévelop-
pement avec une seule génération par an se
situent dans les eaux dures du fleuve Saint-
Laurent (stations 3 et 6) ou en eau mixte
(station 9) tandis que celles qui ont un cycle
de développement avec deux générations par
année se situent dans les eaux douces de la
rivière des Outaouais (stations 2 et 10).

Plusieurs auteurs ont signalé les effets de
la nature physico-chimique et biotique du
milieu sur la biologie des mollusques d’eau
douce (Williams, 1964, 1970; Dussart, 1973,
1976). Harrison et al. (1970) ont mis en évi-
dence l’action du bicarbonate de calcium sur
la dynamique de populations du Planorbidé
Biomphalaria pfeifferi. Hunter (1961a, b),
Eisenberg (1970) et Stanczykowska et al.
(1971) ont montré que les conditions troph-
iques entrainent aussi des modifications dans
la biologie et particulièrement dans les types
de développement de diverses espèces de
mollusques. L'avantage d'un cycle de dével-
oppement avec une seule génération par
année, où les jeunes recrues ne font pas
compétition avec leurs géniteurs pour la
nourriture, est en effet évident. Nos propres
recherches sur la nutrition de L. catascopium
catascopium semblent confirmer cette hy-
pothèse: la qualité du régime alimentaire des
spécimens des stations 3 et 6 était en effet
beaucoup plus faible que celles des individus
des stations 2 et 10 (Pinel-Alloul & Magnin,
sous presse).

Parmi les autres Lymnaeidae, le type de
développement le plus simple avec une seule
génération par année est le plus commun en
zones tempérées nordiques (McCrawn, 1961;
Noland & Carriker, 1946; De Coster & Per-
soone, 1970; Morrison, 1932; Herrington,
1947). En Angleterre, cependant L. peregra et
L. palustris présentent les deux types de
développement (Hunter 1961b, 1975). On a
signalé aussi d'autres variations dans les
cycles de développement: trois générations
par an chez L. trunculata (Walton & Jones
1926), un cycle bisannuel avec une généra-
tion a tous les deux ans chez L. stagnalis
(Berrie, 1965; Pinel-Alloul 1975). La majorité
des Pulmonés ont un cycle de développe-
ment simple mais le cycle avec deux généra-
tions par année semble trés courant chez les
Physidés (De Wit, 1955; Hunter, 1961b;
Clampitt, 1970; Lacasse-Joubert, 1970) et, il
existe aussi chez les Ancylidae (Burky, 1971)
et chez les Planorbidae (Achard, 1973).

LYMNAEA CATASCOPIUM CATASCOPIUM 97

L’oviposition printanière a lieu lorsque la
température de l'eau est d'environ 12 à13°C;
en automne des pontes ont été récoltées
jusqu'en novembre а des températures de 9 à
10°C. Boerger (1972, 1975) indique que la
ponte chez Helisoma trivolvis, H. campanu-
latum et H. anceps ne se déclenche qu'à des
températures supérieures à 10°C, quelle que
soit la photopériode. Le succès de la ponte
d’été-automne ne semble pas devoir être lié a
l’action limitante de la température, car, aux
stations 3 et 6, les températures mesurées en
août et septembre 1970 et 1971 sont com-
parables à celles observées aux stations 2 et
10 et elles sont toujours supérieures à 10°C
(Fig. 1). Il serait plutôt relié à des différences
dans l’âge et la taille à la maturité sexuelle.
Les individus des populations à cycle simple
atteignent généralement la maturité sexuelle
à une taille plus grande que ceux des popula-
tions avec un cycle à deux générations par
année; ils deviennent donc matures plus tard
à lautomne quand la température de l'eau
baisse et pour la plupart d’entre eux la saison
de reproduction se trouve ainsi reportée au
printemps suivant. La même observation a été
faite sur des populations de L. peregra de
Loch Lomond, Ecosse (Hunter 1961b); il
semble que cette différence dans la taille à la
maturité sexuelle soit reliée à la fois aux
facteurs physiques (température), trophiques
(qualité du régime alimentaire) et génétiques.

Chez les populations qui ne produisent
qu'une seule génération par année, le dével-
oppement de cette génération requiert envi-
ron 12 mois (juin à mai-juin de l’année
suivante), mais dans les populations avec un
type de développement à deux générations
par année, la majorité des individus de la
génération printanière vivent moins de six
mois. Le même phénomène a été observé
chez d’autres pulmonés d’eau douce (Geldiay,
1956; Hunter, 1961b; Achard, 1973). Dans les
régions plus chaudes que le Québec, la péri-
ode de recrutement de la génération prin-
tanière est plus longue: de mars à août chez
les L. peregra d'Ecosse (Hunter 1961b),
d'avril à août chez les Ferrissia rivularis de
l'état de New York (Burky, 1971).

Lacasse-Joubert (1970), Clampitt (1970) et
Achard (1973) ont aussi observé l'étalement
de la période d'éclosion des générations
d'été-automne chez des populations de
Physes et de Planorbes. Ce phénomène
laisse supposer que les individus de la
génération printanière n'atteignent pas tous
en même temps la maturité sexuelle et qu'ils

se reproduisent de façon échelonnée aussi
longtemps que la température du milieu le
permet, bien qu'ils soient nés sur une période
de temps assez courte (environ 15 jours).
Ceci est probablement la conséquence des
variations individuelles de la croissance des
individus que l'étalement des histogrammes
de fréquence des longueurs met en évidence
(Figs. 2 et 3).

Le schéma de croissance n'est pas le
méme pour tous les individus. La croissance
des individus de la génération printanière (I)
suit une courbe sigmoïde typique des mol-
lusques d'eau douce (Crabb, 1929; Baily,
1931; Sitaramaiah, 1966). La croissance des
individus de la génération d'été-automne (II)
(Stations 2 et 10) est difficile à préciser par
suite de l'étalement de la période de recrute-
ment des jeunes; il semble toutefois qu'elle
soit faible en automne et beaucoup plus
rapide au printemps. Ces résultats sont com-
parables à ceux obtenus par Clampitt (1970)
et Lacasse-Joubert (1970), sur des popula-
tions de Physes, qui ont un cycle de dévelop-
pement avec deux générations par année.

Nos résultats font aussi ressortir l’action de
la température ambiante sur la croissance
des individus, ce qui a été maintes fois ob-
servé chez d’autres Gastéropodes (Vaughn,
1953; Duncan, 1959; Pinel-Alloul, 1969;
Lacasse-Joubert, 1970; Achard, 1973; Calow,
1973). Dans le milieu naturel, nous remar-
quons en effet que les individus nés au prin-
temps (génération |) et qui survivent à la
période d’hibernation, reprennent leur crois-
sance au printemps suivant à une vitesse
supérieure à celle de l'automne.

Nous avons aussi noté que la croissance
des individus des générations Il se poursuit
faiblement durant l'hiver tandis que celle des
individus des générations | est pratiquement
nulle. Ces résultats sont comparables à ceux
obtenus par Lacasse-Joubert (1970) sur
Physa gyrina du lac Saint-Louis et Calow
(1973) sur Planorbis contortus à Leeds en
Angleterre. Il semble que cet arrêt de crois-
sance soit directement contrôlé par la tem-
pérature car ces deux auteurs ont ramené en
hiver des spécimens du milieu naturel (—
0°C) au laboratoire 1(18°C) et ceux-ci ont
recommencé à croître et à se reproduire. Par
contre, Hunter (1961b) rapporte que L.
peregra continue de croître durant l'hiver au
Loch Lomond (Ecosse) et Clampitt (1970) fait
la même observation pour Physa gyrina et P.
integra au lac Okboji (lowa).

Parmi les facteurs susceptibles d’entrainer

98 PINEL-ALLOUL ET MAGNIN

des variations annuelles dans la croissance
des organismes on pense d’abord à la tem-
pérature. Or nous avons vu que les variations
de la température sont assez semblables au
cours des mois de juillet et août durant
lesquels s'effecture surtout la croissance des
mollusques. On remarque aussi qu'à la sta-
tion 3 les Lymnées sont plus grandes en 1971
qu'en 1970 alors que la température de l'eau
était généralement plus élevée en 1970 qu'en
1971, Achard (1973) a fait exactement les
mêmes observations sur les variations an-
nuelles de la croissance d’Helisoma trivolvis
récoltés en même temps et aux mêmes sta-
tions. ll semblerait donc que les variations
annuelles de la croissance des individus
seraient dues plus aux conditions trophiques
du milieu qu’a la température.

Au laboratoire, le plus petit spécimen
sexuellement mature mesurait environ 8 mm
(station 2). D'après Walter (1969), le système
reproducteur de L. catascopium a une struc-
ture adulte chez les individus de 10 à 11 mm
au lac Houghton, Michigan; le sperme est
présent dans la glande hermaphrodite des
spécimens de 8 mm et les ovules matures
dans ceux de 11 тт. A partir d'observations
effectuées sur le cycle de développement,
Kevan (1942) estime que la taille moyenne
des L. catascopium catascopium sexuelle-
ment matures est de 13 mm en Angleterre.
Au lac Saint-Louis, elle varie de 6.9 à
17.8 mm. Les individus en provenance des
populations à cycle vital avec une seule
génération par année (stations 3, 6 et 9) at-
teignent généralement la maturité sexuelle à
une taille plus grande que ceux des popula-
tions avec un cycle vital à deux générations
par année (stations 2 et 10). La même con-
statation a été faite par Hunter (1961b) sur les
populations de L. peregra du Loch Lomond,
Ecosse. Walter (1969) a aussi observé deux
types de pontes chez une population de L.
catascopium catascopium au lac Houghton
(Michigan), mais en Angleterre, Kevan (1942)
n'a récolté que des pontes typiques (10 a
15 mm de longueur sur 5 a7 mm de largeur).
Се phénomène semble s'étendre à d'autres
espèces de Lymnaeidae; Hunter (1961a)
signale la même chose pour L. peregra en
Ecosse et émet l'hypothèse qu'il s’agit peut-
être là d'un mélange de deux races physio-
logiques.

La grande variation du nombre d'oeufs par
ponte pourrait signifier que cet indice n'est
pas un critère de la fécondité des L.

catascopium catascopium. Van der Steen
(1967), après des études au laboratoire sur la
reproduction de L. stagnalis stagnalis, men-
tionne aussi que le nombre d'oeufs par ponte
(‘capsule size”) et la fécondité sont des vari-
ables indépendantes de la reproduction.

Les résultats de nos élevages en labora-
toire, ont mis en évidence que la température
n'a pas une influence déterminante sur le
nombre moyen d'oeufs par ponte de L.
catascopium catascopium, ce qui avait déjà
été observé chez L. stagnalis stagnalis par
Van der Steen (1967).

Les estimations de fécondité faites en labo-
ratoires (226 a 690 oeufs/Lymnée) s'accor-
dent avec celles rapportées pour d'autres
Pulmonés: Lymnaea peregra pond de 315 à
1155 oeufs au cours de sa période de repro-
duction en milieu naturel (Hunter, 1961a) et
de 200 a 300 oeufs en captivité (Boycott,
1936); Physa gyrina pond de 200 a 300 oeufs
par mois durant son pic de reproduction et un
total de 700 a 1000 oeufs au cours de sa
période de reproduction (Clampitt, 1963) mais
sa fécondité peut aussi étre plus faible: 272
oeufs/individu (De Witt 1954b). Nous n’avons
pas obtenu de corrélation positive entre la
taille des organismes et leur fécondité con-
trairement a ce qu’a obtenu De Witt (1954a)
sur Physa gyrina.

Au lac Saint-Louis, Lymnaea catascopium
catascopium, qui présente déjà un fort po-
tentiel de variations morphométriques
(Clarke, 1973), fait preuve aussi d’une grande
plasticité écologique dans son cycle de dé-
veloppement, sa croissance et sa fécondité.
De nombreux travaux font d’ailleurs mention
de ce phénomène chez d'autres Pulmonés
(Clampitt, 1963; Geldiay, 1956; Hunter,
1961b; Lacasse-Joubert, 1970; Burky, 1971;
Achard, 1973), mais, ce potentiel de variation
serait plus élevé chez les Lymnaeidae et les
Physidae que chez les Planorbidae et les
Ancylidae.

D'après Hunter (1961b), cette plasticité
écologique s'expliquerait par les processus
d'évolution des mollusques pulmonés dans
les milieux d'eau douce qui sont souvent
transitoires et caractérisés par une isolation á
court terme et á petite échelle. Ces organ-
ismes n’auraient pas eu le temps d'atteindre
une spéciation définitive; la sélection à
laquelle ils auraient été soumis aurait produit
seulement des génotypes présentant une
grande flexibilité phénotypique et une grande
capacité d'adaptation.

LYMNAEA CATASCOPIUM CATASCOPIUM 99

CONCLUSION

Notre étude montre que les différents
paramètres qui régissent la dynamique des
populations de Lymnaea catascopium
catascopium au lac Saint-Louis sont sujets à
de très fortes variations:

—le Lymnaeide presente deux types de
développement qui peuvent être mis en cor-
rélation avec la nature chimique des eaux: les
populations qui présentent un cycle de dével-
oppement avec une seule génération par an
se situent dans les eaux dures du Saint-
Laurent (stations 3 et 6) ou en eau mixte (sta-
tion 9); celles qui ont un cycle de dévelop-
pement avec deux générations par années se
situent dans les eaux douces de la rivière des
Outaouais (stations 2 et 10). Ces différences
dans le cycle de développement s’accom-
pagnent de variations dans l'intensité et la
durée des périodes de pontes, dans la com-
position de la population hibernante et dans la
longévité des individus.

—La croissance des individus nés au prin-
temps suit une courbe sigmoïde typique des
mollusques d’eau douce mais elle est sujette
à des variations annuelles et entre les popu-
lations.

—L. catascopium catascopium peut être
mature à une taille inférieure à 10 mm et la
maturité sexuelle est plus tardive dans les
populations a cycle de développement avec
une seule génération par année. Il y a deux
pics de pontes: en juin et juillet puis d'aoút à
novembre et les pontes contiennent en
moyenne de 37 a 49 oeufs.

—La fécondité des populations diffèrent
d'une année à l'autre et d'une station à
l’autre; parmi les populations qui ont un cycle
avec deux générations par année, celle de la
station 2 est plus féconde que celle de la sta-
tion 10; parmi les populations qui produisent
une seule génération par anné, celle de la
station 6 est la plus féconde, vient ensuite
celle de la station 9 et finalement celle de la
station 3.

REMERCIEMENTS

Cette étude a pu être réalisée grace à l’aide
matérielle que nous avons eu du Conseil Na-
tional des Recherches du Canada. Nous
avons bénéficié de l’aide de deux personnes
que nous tenons à remercier particulière-
ment: le docteur A. H. Clarke, Jr. du Muséum
d'Histoire Naturelle d'Ottawa qui nous a aidé

lors de l'identification des Lymnées et le Dr. A.
Stanczykowska de l'institut d’Ecologie de
Dziekanew Lesny (Pologne) qui, lors de son
séjour a notre laboratoire, nous a fait béné-
ficier de son expérience dans les recherches
écologiques sur les Mollusques d’eau douce.

TRAVAUX CITES

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100 PINEL-ALLOUL ET MAGNIN

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LYMNAEA CATASCOPIUM CATASCOPIUM 101

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Ltd., Cat. No. 1258, 368 p.

ABSTRACT

LIFE CYCLE, GROWTH AND FECUNDITY OF FIVE POPULATIONS OF
LYMNAEA CATASCOPIUM CATASCOPIUM (GASTROPODA, LYMNAEIDAE)
IN LAKE SAINT-LOUIS, QUEBEC, CANADA

Bernadette Pinel-Alloul and Etienne Magnin

In following the demography of five populations of Lymnaea catascopium catascopium, the
commonest lymnaeid in Lake Saint-Louis, Quebec, we have studied its life cycle, growth and
fecundity. This species has two kinds of development, one simple with a single generation per
year and a single period of successful reproduction (in spring), the other more complex with two
generations per year and two periods of reproduction (June-July and August-November). These
fundamental differences in the life cycle can be related to water chemistry: the hard, alkaline
waters of the St. Lawrence River and the soft and neutral waters of the Outaouais River. The
growth of individuals fits a sigmoid curve and shows intraspecific and annual variations which
can be explained by differences in the trophic nature of the habitat rather than by physico-
chemical variations. L. catascopium catascopium lays two kinds of egg masses and is sexually
mature at a length less than 10 mm. lts fecundity estimated for the period 18 June 1970 to 23
November 1971 varied from 3,380 to 43,674 eggs depending on the population. In the labora-
tory, each animal laid 273 to 690 eggs at 15° C and 226 to 365 eggs at 20°. The results of our
study have evolutionary implications in relation to the nature of fresh-water habitats.

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MALACOLOGIA, 1979, 19(1): 103-108

PHYLOGENETISCHE ASPEKTE DER RADULAMORPHOGENESE
VON GASTROPODEN

Klaus Kerth

Zoologisches Institut der Universitat Wurzburg (Lehrstuhl |), Róntgenring 10, 8700 Würzburg

,

Bundesrepublik Deutschland

ZUSAMMENFASSUNG

In verschiedenen Pulmonatenfamilien wurde die Morphogenese der Embryonalradula

untersucht.

1. Das fúr die Lungenschnecken typische, gleichmássige Zahnmuster liegt ontogenetisch
erst sekundár vor. Zuerst werden 2 laterale Zahn-Längsreihen angelegt (distiches Stadium).
Nach Auftreten weiterer lateralen Lángsreihen sitzen die Zähnchen in 2 getrennten Arealen. Erst
mit der Ausbildung von Mittelzáhnen entsteht ein einheitliches Areal mit dem typischen

Zahnmuster der Pulmonaten.

2. Die primár distiche, bzw. bilaterale Anordnung der Záhnchen in der Embryonalradula
gleicht auffallend dem in den niederen Molluskenklassen der Caudofoveata und Solenogastres
vorherrschenden Zahnmuster. Daraus wird gefolgert, dass in der Morphogenese der Gastro-
podenradula Anklánge an eine phylogenetisch ursprünglichere Radulaform hervortreten.

EINLEITUNG

Sterki (1893) fand bei verschiedenen
Landpulmonaten eine gesetzmässig ablauf-
ende Radulamorphogenese mit einem auffal-
ligen Formwechsel zwischen Jugend- und
Adultzähnen. Entsprechendes beschreibt
Richter (1961) bei den prosobranchiaten
Atlantiden. In dieser Familie besitzen die evo-
luierteren Arten spezialisierte, einspitzige
Adultzähne. Die frühontogenetisch aus-
gebildeten Zähne rekapitulieren die mehrspit-
zigen Zahnmorphen ursprünglicherer Atlan-
tiden-Arten.

Mit Hilfe einer Quetschmethode, die es
gestattet, serienweise gute Radulapräparate
von Embryonen herzustellen, wurden Radula-
morphogenesen und Radulawachstum in
einer ganzen Reihe von Pulmonatenfamilien
untersucht (Rittmann, 1973; Schier, 1975;
unveröffentlicht). In dieser Arbeit interessiert
speziell die am frühesten fassbare Radula
des Pulmonatenkeimes. An ihr zeigen sich
Besonderheiten des Zähnchenmusters, die
einer phylogenetischen Interpretation unter-
zogen werden sollten. Sie betreffen Über-
legungen zum Aussehen einer phylo-
genetisch ursprünglichen Mollusken-Radula,
wie sie schon mehrfach, zuletzt von Salvini-
Plawen (1972) sowie Minichev & Sirenko
(1974) angestellt wurden.

MATERIAL UND METHODEN
Haltung der Versuchstiere

Helix pomatia (Helicidae). Freilandkäfig,
Futter: Salat, Karotten. Eientwicklung bei
15°C und 12/12 Gleichtag.

Limax flavus (Limacidae). Zucht: siehe Kerth
& Krause (1969).

Lymnaea stagnalis (Lymnaeidae). Zucht bei
25°C, 12/12 Gleichtag, Futter: Frischer
Salat.

Biomphalaria glabrata (Planorbidae). Zucht
bei 25°C, 12/12 Gleichtag. Futter: Frischer
Salat.

Planorbarius corneus (Planorbidae). Zucht
bei 21°C, 16/8 Langtag. Futter: Salat,
Teichdetritus, Wasserpflanzen.

Physa fontinalis (Physidae). Adulti stammen
vom Neusiedler See. Zucht bei 15°C, 12/12
Gleichtag. Futter: moderndes Pflanzen-
material vom Teichboden.

Ancylus fluviatilis (Ancylidae). Zucht bei 15°C,
12/12 Gleichtag. Futter: Steinaufwuchs
vom Bachgrund.

Quetschpräparation der Embryonalradula
Die den Gelegen entnommenen Eier wer-

den von ihrer Hülle befreit. Verdünnte HCI
wird auf den Embryo aufgetropft, um die

(103)

104

& + i
+

ia

>

АВВ. 1. Planorbarius сотеиз. Vorderende der Embryonalradula. Innere Seitenzahn-Langsreihen zuerst
entstanden. 10. Tag, 1400 x Phako (Phasenkontrast). Lr, Langsreihe; Ns, Nebenspitzen; Rm, Radulamem-

bran; Sz, Seitenzahn.

Schale aufzulôsen. Anschliessend 5 min
Mazerieren mit 5% KOH. Der mazerierte
Embryo wird unter dem Deckglas in heisser
Glycerin-Gelatine kräftig gequetscht. Die
winzige Radula liegt fast immer schon aus-
gebreitet. Altersangaben in Tagen nach
Eiablage.

BEFUNDE ZUR EMBRYONALRADULA
Entstehung des Zahnchenmusters

Bei den untersuchten Pulmonaten tritt eine
Radula im Quetschpraparat erstmals 5-12
Tage nach Eiablage auf. Die Radulabildung
beginnt mit der Sezernierung eines termi-
nalen Membranabschnittes (Abb. 1). Hinter
diesem folgen in Langs- und Querreihen
angeordnete Zähnchen. Hintereinander
liegende Querreihen entstehen zeitlich
nacheinander (Isarankura & Runham, 1968;
Kerth & Krause, 1969).

Bei allen untersuchten Arten ausser
Ancylus entsteht die Pulmonaten-Radula auf
dieselbe Weise. Zuerst erscheint ein Paar
Zahn-Längsreihen: die 1. Seitenzähne
beiderseits der Radulamedianen (Abb. 1).
Weitere Seitenzahn-Längsreihen treten auf
beiden Seiten gleichmässig ausserhalb der
schon vorhandenen hinzu. Erst wenn 1-3

Paare lateraler Längsreihen angelegt worden
sind, erscheinen in der Radulamedianen die
Mittelzähne.

Die Embryonalradula ist an ihrem Vorder-
ende zuerst distich, d.h. es existieren nur 2
Längsreihen. Nach Auftreten weiterer later-
aler Längsreihen liegen die Zähnchen
zunächst meist in zwei median deutlich
getrennten Arealen. Dies trifft zu für Helix,
Lymnaea, Planorbarius, Biomphalaria, Physa
(Abb. 2a-e). Bei ihnen treten die Mittelzähne
später als bei den anderen untersuchten
Arten auf. Erst durch das Erscheinen der Mit-
telzähne entsteht eine einheitliche zahn-
besetzte Fläche (Abb. 2c). Von da an weitet
sich das Zähnchenmuster aus, indem ständig
neue Querreihen am Radulahinterende und
neue Längsreihen an den Radularändern
hinzukommen. So entsteht das grossflächige,
gleichmässige Zahnmuster der
Lungenschnecken. Zur histologischen Basis
der Musterbildung vergleiche Kerth & Hänsch
(1977).

Nur bei Ancylus entsteht das
Zahnchenmuster der Embryonalradula
anders. Auf einer schmalen Membran liegen
2 Zähnchenareale hintereinander (Abb.
За, b; |, Il). Das vordere (1) besteht aus 2
Längsreihen mit je etwa 10 hakenförmigen
Dentikeln (Abb. 3c). Dahinter (im Bild:
darunter) folgt ein Areal (Il) mit dem normalen

RADULAMORPHOGENESE VON GASTROPODEN 105

BE D car a

Ya
im жа >
р’? ei

mm.

BE,

АВВ. 2. Primäre Zahnordnung der Embryonalradula. Vordere Querreihen sind älter als hintere. Pfeil zeigt
stets zum Radulavorderende. (a) Physa fontinalis. Am Radulavorderende sitzen die Zähne in 2 lateralen
Arealen. Einheitliche zahnbesetzte Fläche erst nach Ausbildung des Mittelzahnes. (8. Querreihe, Marke !). 12.
Tag, 480 x Phako. Mz, Mittelzahn; Qur, Querreihe. (b) Planorbarius corneus. Paarige Mittelzahn-Höcker
(Marken !). 10. Tag, 1200 x Phako. (c) Planorbarius corneus. Nach Ausbildung der Mittelzähne liegt ein
geschlossenes Zähnchenareal vor, 10. Tag, 1200 x Phako. (d) Planorbarius corneus. Morphogenese des
Mittelzahnes. Bp, Basalplatte; S, Zahnform zum Schlüpfzeitpunkt. (e) Lymnaea stagnalis. Singuläre Mittel-

zahn-Höcker (Marke), 9. Tag, 1200 x Phako.

Zähnchenmuster. Die beiden Dentikelreihen
sind zuerst entstanden. Sie haben einen
grösseren Zwischenabstand als Längsreihen
des hinteren Areals. Ausserdem sitzen ihre
Zähnchen in grösserem Abstand hinter-
einander. Das Zähnchenmuster des Areals
(Il) entsteht später und in der oben beschrieb-

enen, üblichen Weise. Zur Schlüpfzeit ist die
Region (I) bereits abgebaut worden.

Zahnmorphogenese in den Längsreihen

Laterale Reihen. In den lateralen Längs-
reihen der Embryonalradula erkennt man bei
allen untersuchten Arten ausser Physa die

106 KERTH

ABB. 3. Ancylus fluviatilis. Embryonalradula, 13. Tag. (a) Vorderer Radulaabschnitt (1) mit nur 2 Langsreihen.
Dahinter normales Záhnchenareal der Embryonalradula (Il). 246 x Phako. (b) Areal (I) und (Il) auf der
gemeinsamen Radulamembran. 480 x Phako. (c) Hakendentikel des vorderen Radulaabschnittes. 1400 x

Phako.

schon von Sterki (1893) bei verschiedenen
Pulmonaten gefundene auffallige Anderung
der Zahnform. Hinter den vordersten kleinen
Hôckern folgen mehr- bis vielspitzige (echin-
ate) Zahnchen mit vóllig anderem Umriss als
bei Zahnen eines adulten Tieres (Abb. 1, Ns).
Die Adulti der untersuchten Arten besitzen in
den entsprechenden Langsreihen nur noch
ein- bis dreispitzige Zahne. Der Formüber-
gang zeigt sich an Zahnen, die in der spaten
Embryonal- und frühen Postembryonal-
entwicklung gebildet werden. Nur Physa ist
eine Ausnahme. Bei ihren gesägten Zähnen
erhöht sich während der Ontogenese die Zahl
der Schneidendentikel ständig.
Mittelzahn-Reihe. Nur bei Helix und
Lymnaea erscheinen die Mittelzähne sofort
als singuläre Gebilde (Abb. 2e). Bei den
anderen Arten treten im medialen Radu-
labereich zuerst paarige Höcker auf (Abb.
2b). Dann erscheinen fusionierende Höcker
und später wird ein einheitlicher Mittelzahn
sezerniert. (Der definitive Mittelzahn von
Physa ergibt sich aus einer weiteren Fusion

mit dem rechts und links angrenzenden
Seitenzahn.)

DISKUSSION

Die phylogenetisch ursprüngliche
Molluskenradula

Die Vielfalt der heutigen Molluskenradulae
reflektiert Anpassungen an die verschiedenen
Formen des Nahrungserwerbs. Uberlegun-
gen, wie eine ursprüngliche Radula aus-
gesehen haben könnte, konzentrieren sich
auf vergleichend morphologische und embry-
ologische Befunde an den in vielen Merk-

malen primitiven Molluskengruppen der
Caudofoveata, Solenogastres, und Poly-
placophora.

Die Meinungen gehen weit auseinander.
Boettger (1955) hält eine median zweigeteilte
Radula für ursprünglich. Salvini-Plawen
(1972) legt sich auf eine ungeteilte, einheit-
liche Radula als Basisform bei den Weich-
tieren fest.

Innerhalb der niedersten Molluskenklassen

RADULAMORPHOGENESE VON GASTROPODEN 107

Caudofoveata und Solenogastres ist die
distiche Radula (mit 2 Zahn-Längsreihen)
vorherrschend. Nierstrasz (1909) sieht sie für
beide Gruppen als phylogenetisch ursprüng-
lich an. Salvini-Plawen (1972) hält dagegen
die distiche Bezahnung für abgeleitet. Er stellt
eher eine Radula mit vielen Dentikel-Längs-
reihen an die Molluskenbasis. Minichev &
Sirenko (1974) nehmen nach embryolog-
ischen Untersuchungen an, dass die Poly-
placophora ursprünglich eine Radula mit
einer Zahn-Längsreihe besassen. Aus den
Radulaformen bei primitiven Schnecken-
Familien schliessen sie, dass für die Gastro-
poda eine Radula mit vielen Längsreihen und
einheitlicher, flächiger Bezahung ursprünglich
ist.

Radulamorphogenese der Pulmonaten

Frühontogenetische Befunde liegen nun-
mehr zu 5 Stylommatophoren- und 4 Basom-
matophorenfamilien vor (mit Sterki, 1893, und
Schnabel, 1903). Die Embryonalradula
durchläuft zuerst ein distiches Stadium.
Nachdem weitere laterale Längsreihen
auftreten, besitzt sie zwei deutlich getrennte
Zähnchenareale. Erst mit dem Erscheinen
der Mittelzähne vereinigen sich die bilateralen
Areale zu einer einheitlichen Fläche. Dieser
Fusionsvorgang wird bei mehreren Spezies
auch in der Entstehung der Mittelzähne
deutlich. Das typische, sehr einheitliche
Zähnchenmuster der Pulmonaten liegt also
ontogenetisch erst sekundär vor.

Abweichende Befunde von Sterki an 3
verschiedenen Stylommatophoren sind nicht
sehr aussagekräftig. Aus seinen Abbildungen
geht deutlich hervor, dass er damals die
vordersten, winzigen Zahnhöcker der Embry-
onalradula übersehen hat.

Am aufälligsten ist die primär distiche
Bezahnung bei Ancylus ausgeprägt. Bevor
das typische Pulmonatenmuster erscheint,
liegt ein ganz anderer “Radulatyp” vor. Seine
Hakendentikel erinnern an Solenogastres-
verhältnisse. Damit gibt es bei den Lungen-
schnecken eine Parallele zur Opistho-
branchia-Gattung Polycera. Dort entsteht
ebenfalls vor dem definitiven Radula-Areal
eine Region mit distichen Hakendentikeln
(Präradula, Pruvot-Fol, 1926). Auch der
prosobranchiate Viviparus bildet seine Zahn-
Längsreihen nach dem Pulmonatenschema
aus. Erst wenn alle Lateralreihen angelegt
sind, erscheinen die Mittelzähne (Schnabel,
1903).

Die von Sterki (1893) beschriebenen, nur
frühontogenetisch gebildeten echinaten
Zähne sind in fast allen untersuchten Pulmo-
natenfamilien gefunden worden.

Phylogenetische Aspekte der
Radulamorphogenese

In Untersuchungen und Diskussionen über
Radulaevolution spielen Rekapitulations-
phänomene in der Radulamorphogenese
eine wichtige Rolle (Richter, 1961; vergleiche
Einleitung dieser Arbeit; Salvini-Plawen,
1972, Minichev & Sirenko, 1974). Generell
dürfen Rekapitulationen bei kritischer
Beurteilung durchaus als existent angesehen
werden (Rensch, 1960; Mayr, 1967).

Es stellt sich nun die Frage, ob auch in der
Embryonalradula der Pulmonaten phylo-
genetische Reminiszensen hervortreten. Der
Übergang von der primär distichen bzw. bi-
lateralen Bezahung zur geschlossenen
flachigen ist nicht funktionell- durch
Ernährungsumstellung-bedingt. Er ist vollzo-
gen, bevor sich das Scheidenlumen zur
Mundhöhle öffnet (Schnabel, 1903; Cumin,
1972). Man darf deshalb bei aller Vorsicht im
ontogenetisch primär distichen beziehungs-
weise bilateral-zweiteiligen Zähnchenmuster
ein phylogenetisches Relikt erblicken. Es
scheint nicht auf die Pulmonaten beschränkt
zu sein, sondern wird auch bei den dies-
bezüglich kaum bearbeiteten Proso- und
Opisthobranchia angetroffen.

Aus der Radulamorphogenese der Gas-
tropoda kann geschlossen werden, dass der
phylogenetische Weg zu den heutigen
Schneckenradulae über ein distich-bilater-
ales Stadium der Bezahnung gelaufen ist. Ob
man damit einen Schlüssel zur Radula der
Molluskenbasis gefunden hat, ist nicht zu
entscheiden. Jedenfalls sprechen die embry-
ologischen Befunde bei Schnecken gegen die
Auffassung von Minichev & Sirenko (1974)
zur phylogenetisch ursprünglichen Radula an
der Gastropodenbasis.

Ein distiches, beziehungsweise bilateral-
zweiteiliges Zahnmuster ist bei den Soleno-
gastres und Caudofoveata vorherrschend
(Salvini-Plawen, 1969; Götting, 1974).Beide
Gruppen werden von Salvini-Plawen (1972)
trotz deutlicher Spezialisierungen überzeu-
gend in den Umkreis der Stammesbasis
gestellt. Mit der Rekapitulierung eines heute
nur bei diesen niedersten Weichtierklassen
anzutreffenden Zahnmusters tritt bei den

108 KERTH

Gastropoda offenbar ein genetisch fixiertes,
phylogenetisch sehr altes Molluskenmerkmal
zutage.

LITERATUR

BOETTGER, C., 1955, Beitráge zur Systematik der
Urmollusken (Amphineura). Zoologischer
Anzeiger Supplementband, 19: 223-256.

CUMIN, R., 1972, Normentafel zur Organogenese
von Limnaea stagnalis (Gastropoda, Pulmonata)
mit besonderer Berücksichtigung der Mittel-
darmdrúse. Revue Suisse de Zoologie, 79: 709—
774.

GÓTTING, K.-J., 1974, Malakozoologie. Stuttgart,
Gustav Fischer.

ISARANKURA, K. & RUNHAM, N. W., 1968, Stud-
ies on the replacement of the gastropod radula.
Malacologia, 7: 71-91.

KERTH, K. & HANSCH, D., 1977, Zellmuster und
Wachstum des Odontoblastengürtels der Wein-
bergschnecke (Helix pomatia L.). Zoologische
Jahrbücher Abt. Anatomie und Ontogenie, 98:
14-28.

KERTH, K. & KRAUSE, G., 1969, Untersuchungen
mittels Róntgenbestrahlung Uber den Radula-
Ersatz der Nacktschnecke Limax flavus L. Wil-
helm Roux’ Archiv, 164: 48-82.

MAYR, E., 1967, Artbegriff und Evolution. Ham-
burg & Berlin, Paul Parey.

MINICHEV, A. S. & SIRENKO, B. J., 1974, Devel-
opment and evolution of radula in Polyplaco-
phora. Zoologicheskii Zhurnal, 53: 1133-1139.

NIERSTRASZ, H. F., 1909, Die Amphineuren.
Ergebnisse und Fortschritte der Zoologie, 1:
239-306.

PRUVOT-FOL, A., 1926, Le bulbe buccal et la
symétrie des mollusques. |. La radula. Archives
de Zoologie expérimentale et générale, 65: 209-
343.

RENSCH, B., 1960, Evolution above the species
level. New York, Columbia University Press.
RICHTER, G., 1961, Die Radula der Atlantiden
(Heteropoda, Prosobranchia) und ihre
Bedeutung für die Systematik und Evolution der
Familie. Zeitschrift für Morphologie und

Okologie der Tiere, 50: 163-238.

RITTMANN, G., 1973, Radulawachstum und
Zahnmorphogenese von Limax flavus L. bis zur
Geschlechtsreife. Zulass. Arbeit am Zool. Inst.
Univ. Wurzburg (unverôffentlicht).

SALVINI-PLAWEN, L. V., 1969, Solenogastres und
Caudofoveata (Mollusca, Aculifera): Organisa-
tion und phylogenetische Bedeutung. Malaco-
logia, 9: 191-216.

SALVINI-PLAWEN, L. V., 1972, Zur Morphologie
und Phylogenie der Mollusken: Die Beziehungen
der Caudofoveata und der Solenogastres als
Aculifera, als Mollusca und als Spiralia. Zeit-
schrift fur wissenschaftliche Zoologie, 184: 205-
394.

SCHIER, C., 1975, Die Radulamorphogenese in
einigen Familien der Basommatophora
(Pulmonata, Gastropoda). Zulass. Arbeit am
Zool. Inst. Univ. Würzburg (unveröffentlicht).

SCHNABEL, H., 1903, Uber die Embryonalent-
wicklung der Radula bei den Mollusken. |. Die
Entwicklung der Radula bei den Gastropoden.
Zeitschrift für wissenschaftliche Zoologie, 74:
616-655.

STERKI, V., 1893, Growth changes of the radula in
land mollusks. Proceedings of the Academy of
Natural Sciences of Philadelphia, 45: 388—400.

ABSTRACT

PHYLOGENETIC ASPECTS OF RADULA MORPHOGENESIS OF GASTROPODS
Klaus Kerth

The embryonic morphogenesis of the radula was investigated in several pulmonate families.

1. The uniform tooth pattern, typical for pulmonates, arises ontogenetically as a secondary
phenomenon. When the radula begins to be secreted, two longitudinal rows of lateral teeth
appear (distichous phase). In the following stage further rows of lateral longitudinal rows are
added, and the teeth are arranged in two separate areas. When the central teeth are finally
secreted, both patches are united into a uniform area, the typical tooth pattern in pulmonates.

2. The primary distichous, or bilateral, arrangement of teeth in the pulmonate radula con-
spicuously resembles the predominant tooth pattern in the lower mollusc classes of Caudo-
foveata and Solenogastres. Therefore it is concluded that the radula morphogenesis of gastro-
pods reveals vestiges of a phylogenetically more primitive organ.

MALACOLOGIA, 1979, 19(1): 109-128

NON-PELAGIC REPRODUCTION OF SOME ANTARCTIC PROSOBRANCH
GASTROPODS FROM SIGNY ISLAND, SOUTH ORKNEY ISLANDS

G. B. Picken
British Antarctic Survey, Madingley Road, Cambridge, CB3 OET, England

ABSTRACT

The eggs of ten species of Antarctic marine prosobranch gastropods are described from Signy
Island, South Orkney Islands. All the species are oviparous and develop non-pelagically, with
young emerging as crawling juveniles. Two species utilise “nurse eggs” as food for a single
embryo, whereas in the remaining species the majority of eggs in the mass or capsule develop
successfully. Egg development in six of the species was followed by monthly inspection of the
sub-littoral over a two year period, and in four of these the recruitment of juvenileswas monitored
by quantitative sampling. The reproductive patterns of six species are constructed from these
data.

Spawning was largely asynchronous in most species, and spawning and development periods
were prolonged. Periods during which juveniles emerged from the egg masses or capsules were
also lengthy and did not specifically coincide with the austral summer, though there may have
been increased recruitment of juveniles over this period. The significance of non-pelagic devel-
opment is discussed, and egg-size, fecundity, juvenile size at emergence, and seasonality of

reproduction examined in relation to the Antarctic marine environment.

INTRODUCTION

The benthic marine invertebrate faunas of
both the Arctic and Antarctic show a strong
tendency towards non-pelagic development.
The Echinodermata (Einarsson, 1948),
Polychaeta (Curtis, 1977), Lamellibranchia
(Ockelmann, 1958), Crustacea and Gastro-
poda (Thorson, 1935, 1936, 1950), are all
good examples of Arctic groups in which the
majority of species whose reproduction is
known develop without a pelagic larval stage.
In the Antarctic, the echinoderms, lamelli-
branchs, crustaceans, and polychaetes have
adaptations similar to those of their Arctic
counterparts (Thorson, 1936, 1950; Soot-
Ryen, 1951; Dell, 1964, 1972; Bone, 1972;
Bregazzi, 1972; Thurston, 1972; White,
1970). The Antarctic gastropods have been
assumed to follow suit, but for many years the
only evidence of non-pelagic development in
this class was the absence of gastropod
larvae in the plankton of high southern lati-
tudes (Simroth, 1911; Mackintosh, 1934).
Gastropod eggs were mentioned in some
early taxonomic accounts (e.g. Melvill &
Standen, 1898; Strebel, 1904-1907) and
short notes on eggs and egg masses have
appeared more recently (Hedgpeth, 1964,
Gibson et al., 1970). Thorson (1950) ex-
amined, but did not describe, the egg cap-
sules of 16 species of prosobranch gastro-
pods from the “Discovery” collections, and
determined from the capsules that the spe-

cies all seemed to have non-pelagic devel-
opment. Such isolated observations support
the assumption that the majority of Antarctic
gastropods develop without pelagic larvae,
but there are few detailed studies to confirm
this conclusion. The most pertinent are Simp-
son’s (1977) account of the reproduction of
four littoral species at Macquarie Island in
the sub-Antarctic (54°38’S 158°53’E), and
Seager's work on Philine gibba Strebel, 1908,
at South Georgia (54°16’S 36°30’W) (per-
sonal communication).

This paper outlines the life histories of eight
prosobranch gastropod species from the lit-
toral or immediate sub-littoral zones of Signy
Island, South Orkney Islands (60°43’S
45°38’W). The eggs and young of each spe-
cies are described for the first time, establish-
ing that their development is non-pelagic. The
young of six species are known to emerge
from attached egg masses or capsules as
crawling juveniles, and this is inferred for the
remaining two from the state of their well-
developed encapsulated embryos. In addition
a description of the eggs of two unidentified
gastropod species is included, since both il-
lustrate the use of “nurse eggs” as a food
source for developing embryos.

MATERIALS AND METHODS

The eggs and young of six prosobranch
species were studied in detail in the sub-lit-

(109)

110

toral from April 1975 to March 1977. The spe-
cies were: Margarella antarctica (Lamy,
1905), Pellilitorina setosa (Smith, 1875), P.
pellita (Martens, 1885), Laevilacunaria ant-
arctica Martens, 1885, Laevilacunaria (Pelli-
lacunella) bennetti (Preston, 1916) and an
unidentified Trophon, species A. The eggs of
Trophon minutus Melvill & Standen, 1907,
and two unidentified species, were found in-
frequently during this time. The eggs of
Laevilitorina (Corneolitorina) coriacea (Melvill
& Standen, 1907) were examined on a few
occasions in the littoral zone.

All sub-littoral observations and collections
were made by SCUBA diving, particularly in
an area around Billie Rocks, Borge Bay, on
the east coast of the island (Fig. 1). The sub-
strate consists of small rocks and stones set
in gravel, with areas of exposed bedrock,
sand and gravel. The bottom slopes gently
from an almost bare shore-line to about 12 m
depth, where there is a fairly abrupt transition
to a flat, muddy-sand bottom. The slope bears
a varied, and often lush, flora of macro-algae,

PICKEN

characterised by mature Himantothallus
grandifolius, Desmarestia anceps, D.
menziesii and Ascoseira mirabilis plants.
These overlie a rich understorey of Rhodo-
phyceae including Plocamium secundatum,
Pseudophycodrys SP., Cystoclonium
obtusangulum, Gigartina apoda, and
Leptosarca simplex. Approximately 35 spe-
cies of prosobranchs are found in the first
12 m of the sub-littoral. The variety of macro-
algae communities and the secretive loca-
tions afforded by the substrate provide nu-
merous sites for the deposition of egg masses
and capsules.

The developmental state of eggs found in
the sub-littoral was assessed by external ex-
amination each month, and assigned to one
of three broad categories: 1. Recently laid.
Ova uncleaved, or in the early stages of de-
velopment. 2. Developing. Embryos well ad-
vanced in their development, with an obvious
shell. 3. Emerging. Juveniles in the process of
emerging, or young of newly-emerged size
found in the sub-littoral. No attempt was made

I T

à

ae Terra del Fuego

R 50 W

| Г
South Georgia de

Antarctic
Peninsula

WEDDELL °
„SEA

1

South Orkney Islands 0
South ;
Signy Island Sandwich ?
yas o Islands ,
-60S eof <
cas

Billie Rocks
Water samples
BAS Station

6043: Sin

SIGNY
ISLAND

15138 W ma

FIG. 1. The location of the South Orkney Islands. Inset, an outline map of Signy Island showing the position
of Billie Rocks, the water sampling site at the mouth of Factory Cove, and the British Antarctic Survey

Station.

ANTARCTIC PROSOBRANCH REPRODUCTION 111

to quantify the states of development at any
particular date; the presence or absence of
each state was simply recorded.

Spawning was not observed in any species
and eggs were primarily identified by compar-
ing their juveniles with adult specimens. Large
collections of prosobranchs were obtained in
the course of monthly quantitative sampling
using an air-lift suction device built after the
design of Hiscock & Hoare (1973) fitted with a
bag of mesh size 0.5 mm. In the six most ex-
tensively studied species the collections
furnished a progressive size series, from new-
ly-emerged to adult, from which the identifica-
tion of their eggs and juveniles could be con-
firmed. The monthly samples were also used
to monitor the emergence of Pellilitorina
setosa, P. pellita, Laevilacunaria antarctica
and L. bennetti. The juveniles of these spe-
cies were considered large enough to be
adequately collected by the sampling tech-
nique, and for accurate periods of emergence
to be derived from these data.

Additional information on size at emer-
gence and development times was obtained
from laboratory maintained eggs. In the first
year, June 1975-April 1976, individual egg
masses were kept in small jars of seawater in
aquaria cooled by circulating seawater at
ambient temperature. The jars were inspect-
ed every day and newly emerged young re-
moved; the seawater in the jars was changed
weekly. An improved method was used in the
second year, May 1976-March 1977. Single
egg masses were suspended in aquaria from
glass rods, with seawater at ambient temper-
ature circulating freely around them. Masses
were again checked daily and juveniles re-
moved.

The individual fecundity of Margarella ant-
arctica was investigated by counting the eggs
in a series of fresh, mature ovaries. The shell
was measured, then carefully cracked, and
the whole body removed. The ovary was
separated form the rest of the body tissue,
and gently macerated on a slide to spread the
eggs into a thin layer. The eggs were then
counted. The proportion of M. antarctica body
devoted to the ovary was examined in a sec-
ond series of specimens. Ovary and body tis-
sue were extracted as described, dried sepa-
rately at 65°C to constant weight, then
weighed to 0.1 mg.

Adult shells, and large egg masses and
egg capsules were measured to the nearest
0.1 mm with a sliding vernier caliper. Smaller
masses and capsules, individual eggs, ova,

and shelled embryos, were measured with an
eyepiece micrometer. Measurements were
also taken from scale drawings made by
camera lucida. The standard measurement
for the size of adult and juvenile shells was
their height, from apex to the lowest point on
the body whorl. Margarella antarctica and
Laevilacunaria antarctica have broad-based
shells, so the standard measurement of size
for these species was the maximum shell
diameter, measured across the body whorl,
perpendicular to the columellar axis.

The terminology in the descriptions below
follows that adopted by Thorson (1935) and
Lebour (1937). The egg consists of the ovum
surrounded by the egg membrane, albu-
minous layer, egg covering, and gelatinous
sheath. The egg diameter is measured across
the gelatinous sheath. Many such eggs laid
together and covered by further gelatinous
layers constitute an egg mass. The term egg
capsule denotes a protective outer case, con-
taining a fluid in which eggs freely float.

DESCRIPTION OF EGGS AND YOUNG

Order ARCHAEOGASTROPODA
Family TROCHIDAE

Margarella antarctica

Margarella antarctica was conspicuous in
the sub-littoral where adults attained a maxi-
mum shell diameter of 12.8 mm. Gonads
were rarely seen in individuals less than
7.5 mm in diameter and probably only ani-
mals more than 9.0 mm in diameter were
mature.

Margarella antarctica egg masses were
found exclusively on the underside of stones
and small rocks from 4 m to at least 10 m be-
low mean low water (MLW). The eggs were
embedded in a clear gelatinous matrix laid as
a ribbon 2.5-5.0 mm wide, 0.6-0.8 mm thick,
cemented to the rock in a rough circle about
20 mm in diameter (Fig. 2A-D). Eggs were
0.4-0.5 mm in diameter, with a spherical,
bright yellow ovum approximately 0.3 mm in
diameter.

The eggs were characteristically laid in
compound, overlapping masses, presumably
the result of several individuals congregating
and spawning at a favourable site. Individual
fecundity was estimated in September 1976,
i.e. just before the beginning of the spawning
period. Fig. 3 shows the relationship between

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2mm

ANTARCTIC PROSOBRANCH REPRODUCTION 113

2000
1800

1600
1400

1200

1000

A

©
S
=

OV

600

NUMBER OF

200
8-0 9-0
ADULT

SHELL DITA METER

Log Y= 4-7505 Log X -1-8976

N=30

11-0
(mm)

10-0 12-0

FIG. 3. Margarella antarctica. Relationship between the shell diameter and the number of mature ova in the

ovary. Both scales are logarithmic.

adult shell size and the number of ova. Two
complete, single, discrete masses found in
the sub-littoral closely agreed with this esti-
mation. The masses contained 874 and 728
eggs, and from Fig. 3 might have been the
entire spawn of females about 10.5 mm in
diameter, or certainly not less than half that of
an individual about 12.0 mm in diameter.
Recently laid eggs were found each month
from September to February, and shelled
embryos were observed in masses collected

—

in March and May. In May and July newly-
emerged juveniles were found crawling over
masses examined within 1 hr of their collec-
tion in the sub-littoral. It is clear that periods of
spawning and emergence were extended,
with development times probably in excess of
three months.

The young emerged as tiny crawling juven-
iles, with almost transparent opercula. The
shell, of 1-112 whorls, was off-white and bore
fine spiral striae on the lower part of the body

ILL

FIG. 2. Margarella antarctica. A. Complete, recently laid egg mass, containing 874 eggs. B. Developing
eggs. C. Cross-section of the egg ribbon. D. Shelled embryos within the gelatinous matrix. E. Views of the
protoconch; note the spiral striations. F. An older juvenile, with striations still discernible. SS, spiral striations.

114 PICKEN

whorl similar to those seen on older individ-
uals up to about 4.0 mm in diameter (Fig. 2E-
F). The mean maximum shell diameter of 42
juveniles found crawling over masses in May
1976 was 0.56 mm (s.d. + 0.03 mm).
Comparison with the other Signy proso-
branchs which develop non-pelagically shows
that M. antarctica lays many more eggs, the
majority of which appeared to develop suc-
cessfully. Margarita cinerea т northeast
Greenland is similarly adapted, depositing
masses of 200-700 eggs, each about 0.5 mm
in diameter, from which juveniles with a basal
diameter of at least 0.5 mm emerge (Thorson,
1935). Most of the eggs develop successfully.
The diminutive juveniles of Margarella
antarctica are very vulnerable when newly-
emerged, and mortality in the first few months
of life must be high. High mortality is compen-
sated by the increased fecundity of M. ant-
arctica, and this was reflected in the propor-
tion of the tissue weight devoted to the ovary
in September 1976. In Fig. 4 the dry ovary
weight, expressed as a percentage of the
whole body dry tissue weight, is plotted

50

40

30

20

Ovary dry wt.as % of whole body dry м}.

6-0 7-0 8-0 9-0
DIAMETER

SHELL

against shell diameter. Two clusters of points
are seen, showing a clear distinction between
“ripe” and “unripe” ovaries, with a few at an
intermediate stage. Examination of the ova-
ries before drying showed that the “unripe”
ovaries were not being confused with the
post-spawning ovaries of mature females.
The ripe ovary may constitute up to 46% of
the whole-body dry tissue weight in Septem-
ber, and most of this will be lost on spawning.
Fig. 4 also confirms the observation that few
females less than 9.0 mm in diameter were
mature.

Order MESOGASTROPODA
Family LITTORINIDAE

Pellilitorina setosa and P. pellita

Pellilitorina setosa and P. pellita were com-
mon on macro-algae in the sub-littoral and
adults attained shell heights of 17.4 mm and
17.8 mm respectively. Gonads were rarely
distinguished in animals less than about
10.5 mm high, and only individuals more than

13:0

12:0

10:0 11:0

(mm)

FIG. 4. Margarella antarctica. Relationship between shell diameter, and dry ovary weight as a percent of

the total body tissue dry weight.

ANTARCTIC PROSOBRANCH REPRODUCTION 115

C

FIG. 5. Pellilitorina species. A. Recently laid Pellilitorina sp. egg mass. В. Developing Pellilitorina setosa
embryos. C. Apertural view of P. setosa protoconch. D. Apertural view of P. pellita protoconch. PH,

periostracal hairs.

about 13.0 тт high may have been fully
mature. Pellilitorina setosa and P. pellita of
this size were at least 3 years old.

The newly laid egg masses of the 2 species
were indistinguishable and the following de-
scription is applicable to both. Masses were
usually found cemented onto algae from
2 m to at least 10 m below MLW, the fronds of
Gigartina, Pseudophycodrys and Leptosarca
being particularly favoured. The mass initially
appeared as a flattened ball of spherical, clear
eggs embedded in an almost transparent
gelatinuous matrix which rendered the mass
quite firm (Fig. 5A-B). The eggs were de-
posited in a tight circle, with the last often laid

on top of the first, giving the mass a character-
istic bulbous appearance. The eggs were not
an integral part of the matrix and were easily
dissected from it. Eggs were 1.5-1.75 mm in
diameter, with a spherical, pale yellow ovum
0.25 mm in diameter. The mean number of
eggs in 27 masses collected during July-
August 1976 was 40 (s.d. + 10), with a range
of 23-60 eggs per mass. The typical dimen-
sions of a mass containing 40 eggs were,
maximum diameter 11.0 тт; minimum di-
ameter 9.0 mm; thickness 4.5 mm.

Egg masses in all stages, from recently laid
to those with shelled embryos, were found
throughout the year. Pellilitorina pellita juven-

116 PICKEN

iles of newly-emerged size were collected in
sub-littoral samples in all months of the year
except May. Pellilitorina setosa of newly-
emerged size were found in January to
March, July, September, October and De-
cember. Emergence was observed in the
laboratory maintained masses of both species
from June to March. Both P. setosa and P.
pellita spawned asynchronously throughout
the year and juveniles were correspondingly
recruited in low numbers nearly every month.
Development times were prolonged; the
longest period of laboratory maintenance be-
fore successful emergence commenced was
7 months for P. setosa eggs and 6 months for
P. pellita eggs.

The young emerged as crawling juveniles
with opercula, escaping through several small
holes in the upper surface of the mass. The
individuals of any one mass emerged singly
or in low numbers over a period of many days,
probably because the young had to digest the
jelly matrix to escape. Individuals near the
surface therefore escaped more readily than
those deeper in the mass. In the laboratory, P.
setosa masses took from 25 to 56 days for all
juveniles to emerge.

The emergent young of the 2 species were
readily distinguished from each other. Pelli-
litorina setosa juveniles had a pale brown
shell of 112 whorls, with a periostracum bear-
ing numerous columns of very fine short hairs,
identical to those of the adult (Fig. 5C). The
mean height of 391 individuals emerging from
9 laboratory masses in the first year was
1.34 mm (s.d. + 0.06 mm). Pellilitorina pellita
juveniles had a darker brown shell of 1%
whorls and were а little larger, the mean
height of 107 individuals emerging from 6
laboratory masses in the first year being
1.40mm (s.d.+0.08mm) (Fig. 5D). The
periostracal hairs of P. pellita juveniles were
consistently longer and less numerous than
those of P. setosa, and were identical to the
hairs on the unabraded adult P. pellita shell.

Laevilacunaria antarctica

Laevilacunaria antarctica was abundant on
macro-algae in the sublittoral, where adults
attained a maximum shell diameter of
7.1mm. Gonads were not found in animals
less than 4.0 mm in diameter and probably
only individuals more than 5.0 mm in diameter
were fully mature. Laevilacunaria antarctica
of this size were at least 2 years old.

Laevilacunaria antarctica eggs were al-

ways found on algal fronds, especially those
of Ascoseira, Leptosarca and Pseudo-
phycodrys, from 2 т to at least 15 т below
MLW. Even though both species of Des-
marestia bore many young and adult L. ant-
arctica, egg masses were never found on
these algae; their narrow fronds were ap-
parently unsuitable for the deposition of eggs,
and adult L. antarctica descended to the
lower-storey algae to spawn.

The eggs formed a single layer of roughly
rectangular cells each approximately 1.0 by
0.8 mm, deposited in a characteristic oval or
elongated-oval mass. The cells were well
defined, and each contained a spherical, pale
yellow ovum 0.15mm in diameter (Fig.
6A-B). Fifty-nine masses examined in August
1976 contained from 9 to 47 eggs, with a
mean of 22 (s.d. + 7) eggs per mass. The
typical dimensions of a mass with 22 eggs
were, length 5.5 mm; width 4.0 mm; thickness
1.1 mm.

The field observations of L. antarctica egg
masses were the most complete of all the
species studied, and revealed the following
sequence. Recently laid egg masses were
present from January to October and those
with shelled embryos from May to November.
Juveniles of newly-emerged size were found
in sub-littoral samples each month from June
to February. The juveniles of laboratory main-
tained masses from both years also emerged
in all months from June to December.

The development times of egg masses col-
lected in the sub-littoral and maintained in the
laboratory were prolonged. In the first year L.
antarctica masses collected with cleaving ova
took from 81 to 169 days before emergence
commenced, whereas those collected with
shelled embryos took from 3 to 62 days. In the
second year, recently laid cleaving eggs took
from 66 to 102 days before emergence com-
menced, and those with shelled embryos from
7 to 93 days. These observations show the
imprecision of a subjective assessment of an
egg mass's developmental stage, but they are
nonetheless consistent with the estimated
development time of about 150 days which is
deduced below.

The young emerged as crawling juveniles
with opercula, escaping en masse, or within a
few days of each other, through a split in the
upper surface of the mass which often fol-
lowed the sutures between the cells. The
juvenile shell, of 172 whorls, was dark red-
brown, smooth and shiny (Fig. 6E). There was
a characteristic shoulder on the body whorl

ANTARCTIC PROSOBRANCH REPRODUCTION 147

1mm

G

FIG. 6. Laevilacunaria and Laevilitorina species. A. Recently laid Laevilacunaria antarctica egg mass. B.
Well-developed L. antarctica shelled embryos within their cells. C. Laevilacunaria (Pellilacunella) bennetti
egg mass, with 2 shelled embryos and 8 infertile eggs. D. A fragment of Laevilitorina coriacea egg mass
conglomeration, containing a single layer of eggs with well-developed shelled embryos. E. Apertural view of
Laevilacunaria antarctica protoconch. F. Apertural view of L. bennetti protoconch. G. Apertural view of
Laevilitorina coriacea shelled embryo, extracted from the egg mass.

E

118 PICKEN

RERMIEENT

FIG. 7. Laevilacunaria antarctica recruitment. The percentage of newly-emerged juveniles in the population

each month over a 2 year period. - --- O -- - - Juveniles of 1975.

which distinguished it from the protoconch of
Laevilacunaria (Pellilacunella) bennetti (Fig.
6F). The mean maximum shell diameter of
525 individuals emerging from 28 laboratory
masses in the first year was 0.97 mm
(s.d. + 0.06 mm), and that of 443 individuals
from 27 masses in the second year was
0.98 mm (s.d. + 0.06 mm). Although periods
of spawning and emergence were lengthy L.
antarctica did show seasonal periodicity in
reproduction, the evidence for which is as fol-
lows.

The size of newly-emerged L. antarctica is
known from juveniles which emerged from
laboratory maintained egg masses, and from
juveniles collected in the sub-littoral while in
the process of emerging (324 individuals
found from July to October 1976, mean
maximum shell diameter of 0.94 mm
s.d. + 0.08 mm). Individuals with a maximum
shell diameter of 1.1 mm or less are therefore
considered to be newly-emerged. Since L.
antarctica develops non-pelagically, an indi-
cation of the number of eggs completing de-
veloyment each month may be given by the
number of juveniles recruited into the popula-
tion. Recruitment was followed in the size-
frequency histograms derived from the
monthly samples. Fig. 7 shows the number of
newly-emerged juveniles expressed as a
percentage of the total L. antarctica sample
each month. Recruitment has a roughly nor-
mal distribution from June to February, reach-
ing a peak around the end of September in
both years. This may be termed the “mean
date of emergence.” There is no recruitment
over the period March to June. Although
emergence continues into the summer, the
bulk of juveniles have entered the population
by spring. Recruitment in L. antarctica is

x Juveniles of 1976.

therefore seasonal, albeit extending over 7 or
8 months of the year.

A value for the time required to complete
development can be obtained if it is assumed
that the rate at which egg masses are de-
posited during the spawning period (Jan. to
Oct.) has a distribution similar to the rate of
recruitment. If this assumption is correct, a
“mean spawning date” in May is derived. The
interval between the “mean spawning date”
and the “mean date of emergence” is ap-
proximately 150 days, and may be a reason-
able estimate of the development time.

Laevilacunaria (Pellilacunella) bennetti

Laevilacunaria bennetti was common in the
sub-littoral where adults attained a height of
5.5 mm. Their eggs were found cemented to
the fronds of Ascoseira, Leptosarca and
Pseudophycodrys and were easily confused
with smaller L. antarctica masses. Laevila-
cunaria bennetti masses were circular or
oval, 3-4 mm in diameter and 1.0 mm thick,
composed of 10-20 eggs laid as a single layer
of cells similar to those of L. antarctica. The
cells were well defined, slightly distorted rec-
tangles about 0.8 mm by 0.7 mm, and each
contained a spherical, pale yellow ovum
about 0.3 mm in diameter (Fig. 6C).

Because of the difficulty in distinguishing
between L. bennetti and L. antarctica
masses, observations on known L. bennetti
masses were few. Recently laid masses were
found from June to August, and those with
shelled embryos from June to September.
Newly-emerged juveniles were present in the
sub-littoral from June to December. The
general pattern was similar to that of L. ant-
arctica, with lengthy periods of spawning and

ANTARCTIC PROSOBRANCH REPRODUCTION 119

emergence. Development times were also
prolonged; 2 masses maintained in the labo-
ratory took 3 and 4 months respectively be-
fore successful emergence commenced.

The young emerged as crawling juveniles
with opercula. In the few examples observed
all the individuals in the mass escaped within
a few days of each other, through an irregular
hole in the upper surface. The juvenile shell,
of 12 whorls, was dark brown, smooth and
dull, with an angular body whorl (Fig. 6F). The
mean height of 34 individuals that emerged
from laboratory maintained masses in the first
year was 0.77 mm (s.d. + 0.17 mm).

Laevilitorina (Corneolitorina) coriacea

Laevilitorina coriacea is a littoral species
and its eggs were always found cemented to
the sheltered underside of rocks in tidal pools.
A discrete egg mass attributable to one fe-
male was never seen. The egg masses of
several individuals were invariably found in
overlapping conglomerations, so that it was
impossible to measure the size of, or count
the eggs in, any single mass. Fig. 6D illus-
trates a fragment of a “compound” mass in
which there is only a single layer of 12 eggs.
The eggs were approximately 0.6 mm in di-
ameter with a spherical, pale yellow ovum
0.2 mm in diameter.

Masses in all stages of development, from
recently laid to those with shelled embryos,
were found in December and again in March,
on both occasions with many adult L.
coriacea clustered over and around them.
Few observations were undertaken in sum-
mer and no search was made during the win-
ter months, but it is suggested that the L.
coriacea spawning period begins in spring
and that emergence is completed before the
littoral zone freezes again in the autumn.

Newly-emerged juveniles were not found,
but well-developed shelled embryos were
seen in some egg masses. The protoconch,
of about 1 whorl, was light brown and smooth,
and approximately 0.6 тт high (Fig. 6G).
Development was therefore non-pelagic and
the young emerged as crawling juveniles.

Order NEOGASTROPODA
Family MURICIDAE

Trophon Species A

Trophon species A is a carnivore which was
common in the sub-littoral where adults at-

tained a height of 32.8 mm. Trophon species
A is a new species and will be formally de-
scribed from the adult type in a forthcoming
British Antarctic Survey Scientific Report by
Oliver & Picken.

The eggs of Trophon species A were de-
posited in capsules which were always found
cemented in sheltered locations on rocks and
stones, from 2 m to at least 15 m below MLW.
Between 15 and 25 spherical, bright yellow
eggs approximately 0.8 mm in diameter were
loosely held within a tough, dull-yellow or buff,
hemispherical capsule, about 7.5 mm in di-
ameter and 3.0 mm high. There was a char-
acteristic pattern of fine striae running around
the capsule concentrically (Fig. 8A). A semi-
transparent membrane covered the bottom of
the capsule adjacent to the rock surface.

Capsules were found only occasionally and
the data for spawning periods and develop-
ment are consequently incomplete. Eggs
which appeared recently laid were found in
May, August to October, and December.
Capsules containing shelled embryos were
collected in May, July, October and February,
and juveniles in the process of emerging were
found in May and July. Periods of spawning
and emergence were therefore extended and
overlapping, and probably largely aseasonal.

The young emerged as crawling juveniles
with opercula, escaping through a single hole
at the top of the capsule. The juvenile shell, of
172-2 whorls and about 1.5mm high, was
very pale brown, with fine lamellae on the
leading edge of the body whorl (Fig. 8B).
These were the first signs of the lamellae
seen on the unabraded adult shell.

Trophon minutus

Trophon minutus was present in low num-
bers in the sub-littoral, and adults attained a
height of 9.1 mm. Trophon minutus eggs were
deposited in small hemispherical capsules
about 2.5 mm in diameter and 1.0 mm high,
cemented to stones. The few specimens ex-
amined contained either 4 or 6, spherical,
bright yellow eggs approximately 0.4 mm in
diameter (Fig. 80-Е). The capsules were
slightly opaque, very faintly marked with con-
centric striae, and there was a clear area at
the apex through which the juveniles probably
emerged. Because of their small size, cap-
sules were not seen in the sub-littoral but only
discovered while examining monthly samples
microscopically. Field observations are there-
fore lacking and little can be said about peri-

120 PICKEN

FIG. 8. Trophon species. A. Trophon species A, apical and anterolateral views of the egg capsule. В. Apertural
and dorsal views of Trophon species A protoconch, showing the fine lamellae. С. Apertural view of 7. minutus
shelled embryo, extracted before emergence from the egg capsule. D. T. minutus, lateral view of the egg
capsule attached to a chip of stone. E. Apical view of T. minutus capsule, with 4 cleaving eggs. F. Apical view of
T. minutus capsule with 4 shelled embryos. CS, concentric striae.

ANTARCTIC PROSOBRANCH REPRODUCTION 121

ods of spawning or emergence. Newly-
emerged juveniles were not found, but shelled
embryos were seen moving in one capsule
(Fig. 8F). The protoconch was pale yellow,
about 1.0 mm high, and the embryo had an
obvious foot and operculum (Fig. 8C). Devel-
opment was non-pelagic and the young
emerged as crawling juveniles.

The eggs of two unidentified prosobranch
species

Two further types of egg capsule were dis-
covered while examining monthly samples
microscopically. Some capsules of both types
contained numerous recently laid eggs,
whereas others were filled by a single shelled
embryo. The specimens examined therefore
strongly suggested that the majority of eggs
initially laid in the capsules were “nurse
eggs,” which were consumed by the embryo
as it developed. The use of nurse eggs by
Antarctic prosobranchs has not been previ-
ously reported. The embryos of both species
undoubtedly emerged as crawling juveniles.
Both types of capsule remain unidentified,
and have been deposited at the National
Museum of Wales, Cardiff, United Kingdom,
as part of a small collection of Antarctic
prosobranch egg masses and capsules.The
capsules are identified here by their voucher
numbers.

Type 1. NMW 79.1Z.1

The capsules were oval, about 1.3mm
long, 0.9mm wide and 0.7 mm thick, and
virtually transparent (Fig. 9A). One capsule
contained approximately 350 eggs, each
0.09 mm in diameter, and others were com-
pletely filled by a single shelled embryo (Fig.
ЭВ). The pale brown protoconch, of 172-134
whorls, was approximately 1.0 mm high. The
capsule and protoconch may have been
those of Prosipho species A (order Neogastro-
poda, family Buccinulidae), which was com-
mon to the sub-littoral from 2 m to 12 m below
MLW. Prosipho species A is a new species
and will be formally described in a forthcom-
ing British Antarctic Survey Scientific Report
by Oliver & Picken. The protoconch NMW
79.17.1 was very similar to the apices of older
specimens of Prosipho species A (Fig. 9C).

Type 2. NMW 79.1Z.2

A distinctive small goblet-like capsule which
was found attached to algal strands by a

short, broad-based peduncle. The Capsule
had an oval top, maximum diameter 0.9 mm;
minimum diameter 0.6mm, and with the
peduncle stood 1.1 mm high. Some capsules
contained about 200 recently laid eggs, each
about 0.07 mm in diameter (Fig. 9D-E). One
specimen was found with a developing em-
bryo and about 80 nurse eggs, whereas the
remaining capsules contained a single pale
brown shelled embryo of about 1 whorl,
0.8 mm high, with no nurse eggs (Fig. 9F).

DISCUSSION

The ten species of Antarctic prosobranch
gastropods whose egg masses or capsules
were studied at Signy Island are aii oviparous.
The embryos of each species develop without
a free pelagic larval stage, and emerge as
crawling juveniles. Powell (1960) lists approx-
imately 500 prosobranch species from the
Antarctic and sub-Antarctic biogeographical
provinces (Powell, 1960, 1965); the reproduc-
tion of 17 of the species is now known, and
only 3 have a pelagic larva (Table 1). If the
species with a wholly sub-Antarctic distribu-
tion are eliminated, namely Nacella (Patini-
gera) macquariensis (Finlay, 1927), Can-
tharidus coruscans (Hedley, 1916), Diacolax
cucumariae Mandahl-Barth, 1946, and
Macquariella hamiltoni (Smith, 1898), 13 re-
main with only 1, Nacella (Patinigera)
concinna (Strebel, 1908) having a pelagic
development.

There is clearly a predominance of non-
pelagic development in the Antarctic proso-
branchs studied to date, and this is to be an-
ticipated from the literature on the reproduc-
tion of the benthic marine invertebrates of
both polar regions. The prosobranchs were
cited by Thorson (1936) as a particularly good
example of the trend towards non-pelagic
development in Arctic invertebrates, and they
are apparently an equally good example of
this tendency in the Antarctic. Thorson (1950)
attributed the evolution of similar modes of
reproduction in polar marine invertebrates to
the comparable conditions in the coastal wa-
ters, the key factors being the low tempera-
ture and short periods of phytoplankton pro-
duction. He thought that in such situations
there would be a strong selective pressure for
the adoption of some form of non-pelagic
development, either by means of egg cap-
sules, brood protection or viviparity. Vance
(1973) suggested that lecithotrophic larvae
would be favoured in conditions of poor food

PICKEN

122

1mm

Imm

FIG. 9. Two unidentified egg capsules. A. NMW 79.1Z.1, apical and lateral views of a recently laid capsule,
filled with nurse eggs. B. NMW 79.1Z.1, apical view of a capsule containing a single shelled embryo. C. A
young Prosipho species A, showing a protoconch similar to that of the encapsulated embryo in B, above. D
and Е. МММ 79.1Z.2, lateral and apical views of the egg capsule filled with nurse eggs. Е. NMW 79.122,
lateral views of a capsule containing a single shelled embryo. The peduncle is broken in this specimen. PL,

demarcation of the protoconch outer lip; AS, algal strand; P, peduncle.

ANTARCTIC PROSOBRANCH REPRODUCTION

123

TABLE 1. The reproduction of Antarctic and sub-Antarctic prosobranchs. The allocation of each species’
type-locality and range to the Antarctic or sub-Antarctic biogeographical provinces follows Powell's (1965)

definition of these regions.

Species

Nacella (Patinigera) concinna
Nacella (Patinigera) macquariensis

Cantharidus coruscans

Margarella antarctica
Margarites refulgens

Source

Shabica (1971, 1976)

Simpson (1972)
Simpson (1977)

This paper

Arnaud (1972)

Pellilitorina setosa This paper
Pellilitorina pellita This paper
Laevilacunaria antarctica This paper
Laevilacunaria bennetti This paper
Laevilitorina coriacea This paper

Laevilitorina caliginosa
Macquariella hamiltoni
Diacolax cucumariae

Simpson (1977)
Simpson (1977)

Mandahl-Barth (1946)

Trophon species A This paper
Trophon minutus This paper
Two unidentified species This paper

Distribution Development
Antarctic & sub-Antarctic Pelagic
Sub-Antarctic Pelagic
Sub-Antarctic Pelagic
Antarctic Non-pelagic
Antarctic & sub-Antarctic Non-pelagic
Antarctic & sub-Antarctic Non-pelagic
Antarctic Non-pelagic
Antarctic Non-pelagic
Antarctic Non-pelagic
Antarctic Non-pelagic
Antarctic & sub-Antarctic Non-pelagic
Sub-Antarctic Non-pelagic
Sub-Antarctic Non-pelagic
Antarctic Non-pelagic
Antarctic Non-pelagic
Antarctic? Non-pelagic

TABLE 2. Comparisons of the egg size, fecundity and size of newly-emerged juveniles of some Arctic and
Antarctic prosobranchs which develop non-pelagically.

Species Locality Diameter (mm) Number Juvenile (mm) Source
Margarella antarctica Antarctic Egg 0.45-0.50 200-2,000/ovary 0.56 diam. This paper
Margarita cinerea Arctic Egg 0.50 200-700/mass >0.50 diam. Thorson (1935)
Laevilacunaria antarctica Antarctic Ova 0.15 9-47/mass 0.97 diam. This paper
Laevilacunaria bennetti Antarctic Ova 0.30 10-20/mass 0.77 height This paper
Laevilitorina coriacea Antarctic Ova 0.20 2 >0.60 height This paper
Laevilitorina caliginosa Antarctic Ova 0.18 9-16/ovary 2 Simpson (1977)
Littorina obtusata Arctic Ova 0.25 90-150/mass 2 Lebour (1937)
Pellilitorina setosa Antarctic Ova 0.20 23-60/mass 1.34 height This paper
Pellilitorina pellita Antarctic Ova 0.20 23-60/mass 1.40 height This paper
Trophon species A Antarctic Egg 0.80 15-25/capsule 1.50 height This paper
Trophon minutus Antarctic Egg 0.40 4-6/capsule >1.00 height This paper
Trophon muricatus N. temperate Egg 0.48 5-8 capsule >0.64 diam. Lebour (1936)
Trophon clathratus Arctic 2 9-12/capsule 1.00 height Thorson (1940)
Trophon truncatus Arctic Egg 0.40 2 1.20 height Thorson (1946)
Trophon geversianus Falkland Is. Egg 0.23-0.30 74-112/capsule 2.50 height Melvill & Standen (1898)

availability and low water temperature. He
further proposed that low temperatures, by
increasing the development time, would con-
fer an advantage on non-pelagic develop-
ment. Mileikovsky (1971) reviewed the rela-
tionships between types of development in
benthic invertebrates and environmental and
ecological factors, and Simpson (1977) dis-
cussed several salient points with particular
reference to sub-Antarctic molluscs. Two
aspects of the reproductive adaptations of the
Antarctic prosobranch gastropods at Signy
Island will be considered further, the first be-
ing egg size and fecundity.

Species which develop without a pelagic
larval stage produce fewer, larger eggs than
those with a pelagic development (Thorson,
1950; Mileikovsky, 1971; Spight, 1976). This
may be a more efficient use of energy than
the production of numerous pelagic larvae

(Chia, 1970; Vance, 1973), an important con-
sideration if the resources available for repro-
duction were limited. Large eggs will give rise
to larger juveniles (Amio, 1963), which will
generally have a better chance to survival
than smaller juveniles (Smith & Fretwell,
1974; Spight, 1976). In the Northern Hemis-
phere, Thorson (1936, 1950) showed that
Arctic species of lamellibranchs, crustaceans
and gastropods produced larger eggs than
more southerly species. There are no such
data for the Southern Hemisphere proso-
branchs, but comparisons between Arctic and
Antarctic species of the same or closely re-
lated genera may be valid. The available ex-
amples show that Arctic and Antarctic species
lay eggs of aproximately the same size, and in
numbers of the same order of magnitude.
Their juveniles are also of equivalent sizes
(Table 2).

124 PICKEN

The Antarctic prosobranch species so far
studied do not utilise nurse eggs to the same
extent as Arctic prosobranchs. Only 2 of the
13 Antarctic species produce nurse eggs,
whereas 15 of the 30 Arctic prosobranchs
discussed by Thorson (1936) show this mode
of reproduction. This may reflect a tendency
towards the use of nurse eggs in the genera
found in the Arctic, rather than a particular
characteristic of Arctic as opposed to Ant-
arctic reproduction.

The second important aspect of any repro-
ductive adaptation is the timing of gameto-
genesis and spawning, and consequently of
the release of young into the sub-littoral.
Marked seasonality of reproduction is com-
mon in Arctic and Antarctic invertebrates
(Giese & Pearse, 1974), with most benthic
species taking advantage of the elevated
summer production levels. Thorson (1936)
derived reproductive cycles for 15 species of
sub-littoral Arctic prosobranchs from periodic
examinations of their egg masses. He con-
cluded that the majority of reproduction took
place during the summer, and that embryonic
development was generally completed within
this period.

Fig. 10 shows the reproductive patterns of
the eight identified prosobranch species from
Signy Island. This synopsis is compiled from
two year’s observation, and follows the prob-
able periods of spawning, development and
emergence of each species over one year.
Periods of spawning and emergence are pro-
longed in most species, and the emergence of
juveniles does not specifically coincide with
the summer.

Maritime conditions are obviously relevant
to the reproductive patterns of gastropods in
the littoral and immediate sub-littoral zones of
the Antarctic. Signy Island lies well within the
Antarctic Convergence and coastal conditions
are highly seasonal. The annual cycle of mari-
time events, outlined below, were remarkably
similar for the two years of this study and belie
the fact that conditions often vary greatly from
year to year.

The sea was free of fast-ice from about
November to June, and there was a pro-
nounced phytoplankton bloom in December—
January when the level of incident light was
highest. Seawater temperature at a depth of
6m in Borge Bay reached a maximum of
about + 1°C towards the end of January. Sea-
ice formed late in May, thickening to more
than 1 m through the winter. Light levels were

lowest in August-September, and seawater
temperature reached a minimum of —1.8°C
in September. The sea-ice remained firm over
the main study area throughout both winters,
though there were temporary areas of open
water within 1km during the second winter.
The sea-ice broke out rapidly at the end of
October in both years.

White (1977) showed that the onset and
duration of fast-ice cover at Signy Island was
highly variable from one year to the next, and
surmised that this must lead to irregularities in
the summer primary production. He proposed
a hypothesis of possible reproductive adapta-
tions for Antarctic marine invertebrates where
the timing of reproduction was largely con-
trolled by the degree to which adults or young
were dependent on the summer production.
Most Signy prosobranchs appear to be rela-
tively independent of the elevated summer
production levels, though the patterns shown
in Fig. 10 are open to a variety of interpreta-
tions. All the species except Trophon are
herbivorous and probably graze the epiphytic
algae covering rocks and macro-algae fronds.
It is not known if their diet, or the amount of
food available, changes with the seasons.
Any interpretation of the seasonality of repro-
duction in the light of White's hypothesis
would therefore be open to criticism without
evidence from feeding studies. Bearing this
reservation in mind, the reproductive periodic-
ity of each species is outlined below, and
some speculations on timing offered. The evi-
dence at this stage suggests that neither
adults nor young of any species are totally
dependent on the summer production, vari-
able as it is in onset and duration, but rather
that the young of some winter-emerging spe-
cies are able to benefit from the increased
production whenever it occurs.

The data for Trophon species A, T. minutus
and Laevilitorina coriacea have been briefly
discussed already and are insufficient for fur-
ther analysis. Margarella antarctica egg
masses were not easily found and newly-
emerged juveniles were too small to be quan-
titatively collected in samples. The incomplete
data indicate spawning from late winter to
summer, with emergence in autumn and early
winter. The mature ovaries of M. antarctica
constituted between 30% and 46% of the
whole body dry tissue weight, and it seems
unlikely that M. antarctica would spawn more
than once a year. Spent adults probably begin
gametogenesis during summer and autumn,

ANTARCTIC PROSOBRANCH REPRODUCTION 125

| PAST GE I@E

SUMMER| AUTUMN | WINTER| SPRING| SUMMER |AUTUMN |WINTER
Dec-Feb Mar-May Jun-Aug Sep-Nov

MARGARELLA
ANTARCTICA

PELLILITORINA
SP

6 3
?----9-- ©
2=--22--- 22

2222722777777 = =
ZA = = = = =

PELL ITA
SETOSA

С А

АМТАВСТТСА

LAEVILACUNARIA
BENNETTI

TROPHON
SPRECIESFA

TROPHON
MINUTUS

LAEVILITORINA
CORIACEA

LEGEND. С) Recently laid eggs
Shelled embryos
Emergent juveniles

?---I----J-
?--©9----I--

-- - - - Category presumed
present

? Duration unknown

FIG. 10. Synopsis of the reproductive patterns of eight Antarctic prosobranchs from Signy Island.

possibly benefiting from the increased sum-
mer production, in preparation for spawning in
the following spring-summer.

The reproductive periodicity of Pellilitorina
setosa, P. pellita, Laevilacunaria antarctica
and L. bennetti is better known, and in each
species the data for both years agree closely.
Fig. 10 is probably an accurate summary of
the reproductive pattern. Pellilitorina setosa

and P. pellita spawn throughout the year, and
qualitative observations of their egg masses
will not reveal seasonal fluctuations in spawn-
ing. Possible fluctuations may be registered
as changes in the rate of juvenile recruitment
during the year, but the interpretation of such
data is complicated by variations in the total
numbers sampled each month. Both the Pelli-
litorina species appear to recruit juveniles at a

126

steady, low rate more or less throughout the
year. There may be some increase in the
number of newly-emerged young in both
populations during the spring and summer
months.

Laevilacunaria antarctica and L. bennetti
show seasonality of reproduction the most
clearly. Laevilacunaria antarctica spawns

from January to October, and L. bennetti

probably spawns over the same period. Both
species have periods of emergence extend-
ing from mid-winter to mid-summer, but in L.

PICKEN

antarctica at least, a definite seasonal recruit-
ment to the population can be demonstrated
(Fig. 7). The majority of L. antarctica and L.
bennetti juveniles emerge during the winter
and early spring, and will therefore be present
in the sub-littoral when food becomes more
plentiful in the summer.

The effect of the summer primary production
can be seen in the first year’s growth of juven-
ile L. antarctica (Fig. 11). The sigmoid curve
is interpreted as follows. During the first three
or four months of the period of emergence

== ‘a
Е . e
Е 26 р
®
a 1975
UN =
< 20 er 50
= 1 \ 40
ы 1.5 - x \ 30
= ut \ 20 =
> ; he 10 5
= se mn ттт A 3
e en. gl aS +
Sa
=)

ce =
a.
E o ¡aa
< 2:5 о
= =
ia 1976 u x
— 2.0
LE
YN
Z 15
u)
>=

1:0

FIG. 11. [аеуйасипапа antarctica. The first year’s growth of juveniles in relation to the phytoplankton

bloom. ®

mean diameter of the juvenile class. ---- x --- -concentration of chlorophyll a.

(The chlorophyll a data are from Brook 1975, 1976. Water samples were taken from 6 m depth at the mouth
of Factory Cove, approximately 250 m from Billie Rocks.)

ANTARCTIC PROSOBRANCH REPRODUCTION 127

there is little increase in the mean size of
juveniles. Young emerging in mid and late
winter do not grow appreciably in their first
few months of benthic life. The mean size of
the class begins to increase in October-
November, and the period of fastest growth
extends from December to February. The
elevated summer growth rate is probably due
to the greater abundance of food, possibly
enhanced by the higher seawater tempera-
tures of the shallow sub-littoral during this
time. The correlation between elevated pri-
mary production and the accelerated growth
rate of L. antarctica juveniles is shown in Fig.
11. The decline of the growth rate in autumn
coincides with the reduction in primary pro-
duction at this time of year.

In the polar environment reproduction with-
out pelagic development is apparently a more
efficient adaptation for the majority of benthic
invertebrates. Reproduction with non-pelagic
development is common but by no means
universal, and Mileikovsky (1971) has pointed
out that polar species which have retained
pelagic development are often among the
most widespread and dominant members of
the fauna. The occurrence of non-pelagic
development has important implications. The
absence of pelagic larvae which can be
transported by oceanic currents reduces a
species’ ability to colonise new territory and
expand its geographic range. It restricts the
rate at which populations will be re-estab-
lished after being eliminated by some local
catastrophe, and reduces the gene-flow be-
tween separated populations. These conse-
quences of non-pelagic development are all
seen in the sub-littoral invertebrate fauna of
the Antarctic, where many species have a re-
stricted range and species endemism is high.
Local, nearshore, prosobranch populations
are maintained by the production of relatively
few, highly viable juveniles, which emerge di-
rectly into the most favourable habitat along-
side the adults. It seems that dispersion is
largely achieved by the chance transport of
adults or egg masses attached to macro-
algae, and this may explain why many of the
shallow sub-littoral prosobranchs have
ranges restricted to the Palmer Peninsula and
the islands of the Scotia Arc.

ACKNOWLEDGEMENTS

| am indebted to all my companions at the
British Antarctic Survey Base on Signy Island
from 1975 to 1977, for their cheerful and will-

ing assistance with the diving programme on
which this study depended. In particular |
should like to thank J. Brook, D. Marsh, J. Hall
and D. Allan for their untiring support under-
water. | am grateful to Dr. G. Oliver, Dr.R.
Ralph and M. G. White for reading and com-
menting on the manuscript.

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MALACOLOGIA, 1979, 19(1): 129-146

COURTSHIP OF LAND SNAILS OF THE GENUS PARTULA

Carol Scola Lipton and James Murray
Department of Biology, University of Virginia, Charlottesville, Va. 22901, U.S.A.

ABSTRACT

The land snails of the genus Partula inhabiting the island of Moorea in French Polynesia form
a closely related group with some members only partially reproductively isolated from each
other. This paper describes the mating behavior of the two most widely distributed and distinctive
species. The study provides a basis for the evaluation of the role of behavior as an isolating
mechanism in Partula.

Partula suturalis and P. taeniata are ovoviviparous hermaphrodites normally reproducing by
cross-fertilization but occasionally resorting to self-fertilization. Courtship is non-reciprocal with
one partner acting as a male and the other as a female.

Courtship can be described in five stages: 1. Foreplay consists of curving turns, the form
differing according to species, and pursuit. 2. Early courtship takes the form of shell wandering
by the male on the shell of the female. The pattern of shell wandering is species-specific. 3. Late
courtship consists of the probing of the body of the female by the penis of the male. Shell
wandering separates bouts of probing. Late courtship may include biting, kissing, head entwin-
ing, shell twirling, head prodding, or touching tentacles. 4. Copulation takes place after pro-
longed probing. Tentacles are withdrawn. Copulation may be very brief or may extend for more
than an hour, according to species. 5. Reversal often follows copulation, with the two partners
exchanging roles for a second complete courtship.

The details of courtship differ in the two species. Whether the differences are sufficiently great
to serve as isolating mechanisms has not been determined.

Of particular interest is the behavior of pairs of P. suturalis of opposite chirality. The male
partner carries out the courtship as if the female were of his own type, with the result that probing
is directed to the side of the head away from the genital opening. It is suggested that this

behavior may result in partial reproductive isolation of dextral and sinistral animals.

INTRODUCTION

The land snails of the genus Partula make
up a conspicuous part of the fauna of the vol-
canic islands of Polynesia. These animals are
remarkable not only for a rich polymorphism
in the color and form of the shell but also for a
pattern of speciation that has resulted in ex-
tensive sympatry of similar species.

Knowledge of the distribution and variation
of Partula is based on the studies of Professor
H. E. Crampton during the early decades of
this century (Crampton, 1916, 1925, 1932).
His account of the island of Moorea in the
Society Islands (Crampton, 1932) is especi-
ally thorough, describing in detail the relation-
ships among the species found there. More
recently Clarke and Murray have re-examined
the Moorean Partulae. They have worked out
the genetics of the polymorphism in two of the
species (Murray & Clarke, 1966, 1976a, b),
described the pattern of variation in natural
populations (Clarke, 1968; Clarke & Murray,
1969, 1971), and discussed the evidence for
incomplete speciation in two pairs of species
(Murray & Clarke, 1968; Schwabl & Murray,
1970).

(129)

According to Crampton there are eleven
species of Partula on Moorea (Crampton,
1932; Crampton & Cooke, 1953). Two of
these have subsequently been removed to
the genus Samoana (Kondo, 1973). Although
it is difficult to decide how many of the remain-
ing nine should be considered “good” spe-
cies, it is common for as many as four distinct
forms to occur sympatrically. This is the case
for Partula suturalis, P. taeniata, P. moore-
ana, and P. mirabilis in the central part of the
island and for P. suturalis, P. taeniata, P.
tohiveana, and P. mirabilis farther east. There
are indeed slight differences of ecological
preference, but without any question the op-
portunity for interspecific hybridization exists.

Under these circumstances it is of interest
to investigate possible mechanisms that
might be responsible for the maintenance of
reproductive isolation. To this end we have
observed the mating behavior of two of the
species, Partula suturalis and P. taeniata.
Since these two species appear to be the
most distinct morphologically and ecological-
ly, as well as being the most widely distributed
on Moorea, they may be expected to exhibit
the greatest differences in behavior of all the

130 LIPTON AND MURRAY

Moorean species. In addition, P. suturalis is
unusual in displaying true chiral polymorph-
ism. Populations in some areas are all dextral,
others are all sinistral, while still others are
amphidromic. It has been suggested that dif-
ferences in chirality may function as an inter-
specific isolating mechanism in Partula, and
indeed there is some evidence for a restriction
of random mating between dextral and sinis-
tral P. suturalis in nature (Clarke & Murray,
1969). Descriptions of the mating behavior of
these species and morphs will serve as a
basis for the comparative study of other spe-
cies and for the investigation of mating be-
havior in interspecific crosses.

MATERIALS AND METHODS

Origin of the Animals. Collections of Partula
from Moorea were made by Bryan Clarke and
James Murray in the summers of 1962, 1967,
and 1968. Snails used in this study were ob-
tained either directly from these collections or
as offspring of genetic crosses established
from the 1962 samples. Collecting localities
are shown in Fig. 1.

Faatoai

o
8

Maintenance of Animals. snails were main-
tained as described by Murray & Clarke
(1966). They were kept in plastic boxes lined
with moistened toilet paper and were fed a
diet of oatmeal, lettuce, and powdered natural
chalk.

Breeding Biology. Partula suturalis and
taeniata are ovoviviparous hermaphrodites.
Self-fertilization is possible but occurs only
rarely (Murray & Clarke, 1966, 1976a, b). The
genitalia of Partula are asymmetrical. In dex-
tral individuals the genital opening is on the
right side of the body; in sinistrals it is on the
left.

Selection of Animals for Study. Individuals
were chosen for mating on considerations of
maturity, health, shell condition, and origin.
Maturity can be judged by the development of
a reflected lip to the shell. Health and general
physical condition are indicated by activity
and willingness to feed. Since the shell is the
“stage” on which courtship occurs, only ani-
mals with shells free from malformations were
chosen.

For each trial, individuals were selected on

FIG. 1. A map of Moorea, French Polynesia, showing the valleys of origin of the animals used in this study.

Apootaata is a division of the inner part of Faatoai.

PARTULA COURTSHIP 131

the basis of: 1) species, 2) valley of origin, 3)
previous mating experience, and 4) for P.
suturalis, direction of coil. Since we wished to
use only individuals with no hint of hybrid
ancestry, localities where snails show evi-
dence of hybridization with other species
were avoided. In four cases, however, we
were forced to use animals from Faamaariri
(see Table 1), where hybridization with P.
aurantia is a possibility. In the initial studies of
animals born in nature, individuals from the
same local valley were paired in order to
detect intraspecific variation. In trials with
laboratory reared animals, pairs with previous
mating experience and proven fertility were
used in most instances. A few matings were
set up with virgin animals, isolated from birth.
In P. suturalis the direction of coil was taken
into consideration. Individuals of the same
chirality were used initially, and then observa-
tions were extended to mixed pairs.

Preparation of Animals for Observation.
From the experience of the genetic program,
it appears that isolation increases the read-
iness of individuals to court and that a short
period of aestivation in dry conditions stimu-
lates activity when moisture is restored.
Hence the animals were maintained in isola-
tion and without moisture for at least a week
prior to the trials, except in those cases where
the effect of isolation was being tested. Since
attempts to stimulate courtship by reducing
illumination were unsuccessful, no special ef-
forts were made to control illumination during
the trials.

Observation. In single-pair matings, part-
ners were placed in a clear polystyrene box
(11.5 x 11.5 x 3.3 cm) on a freshly moist-
ened paper substrate. All the actions of the
animals were recorded. A clock and stop-
watch were used to keep time. Photographs
of various stages of courtship were made with
a 35mm camera. The observing room had
overhead lighting, and the temperature
ranged from 18 to 21°C. Observations were
carried out both during the day and in the
evening.

In group matings, 4 to 12 individuals were
placed in a larger polystyrene box (19 x 13.9
x 9cm) with a moistened paper substrate.
Half of the animals were physically isolated
prior to the trials; the other half were kept to-
gether. In one trial involving virgins tested as
a group, all animals were previously isolated.
Prior aestivation was enforced for all the ani-
mals. In group trials each shell was marked
with an identifying number written with a

waterproof felt-tipped pen. The animals
showed no visible reaction to the ink.

Tables 1 and 2 list the histories of animals
used in this study and the type of test in which
they were used.

Analysis. Each successful mating was
analyzed to characterize the component
movements. Matings of similar type were then
compared to establish the typical sequence of
events. Diagrams of the movements of male-
acting animals were made for each courting
pair and were used to analyze elements of the
courtship. Examples are shown in Figs. 2-3.

RESULTS
Partula suturalis
Description of Courtship

Of 41 trials conducted with P. suturalis, 25
produced useful results, the remainder show-
ing either complete inactivity (if so, trials were
terminated after 30 minutes) or random ex-
ploratory behavior (if so, trials were termin-
ated after 120 minutes). In order to organize
the description, courtship has been divided in-
to five stages: Foreplay, Early Courtship, Late
Courtship, Copulation, and Reversal. Table 1
summarizes the behavioral elements re-
corded in each of these stages.

Foreplay. Foreplay is defined by frequent
meetings, departures, and temporary shell
mountings, sometimes including pivoting and
pursuit. Pivoting consists of a series of C- and
S-shaped turns made by a pair. The animals
are positioned at right angles to one another
and turn sequentially so that one animal
moves into a curve as the other moves out.
On approaching one another, there is usually
some contact of tentacles or shells. Pursuit
consists of circling turns toward one animal
made by its partner without reciprocation.

Foreplay usually takes the following form.
After wandering about the box, A and B meet.
A mounts the shell of B and moves from lip to
apex. A then dismounts and the pair begin to
separate. Pursuit or pivoting follows. In pur-
suit B continues on a straight path while A
approaches with C- and S-shaped turns. On
contact A will mount B. A may follow the slime
trail of B. In pivoting both animals make
sequential turns until they touch, when mount-
ing or separation will follow.

Early Courtship. Early Courtship is defined
by shell mounting followed by shell wander-

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133

PARTULA COURTSHIP

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134 LIPTON AND MURRAY

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FIG. 2. An ideogram of shell wandering during Early Courtship of Partula suturalis. The outline of the shell
represents the female-acting animal. The directed line shows the path of the male in a typical, continuous

sequence of movements.

ing. At this stage, sex roles become differen-
tiated, the male-acting animal (called simply
the male hereafter) mounting the shell of the
female-acting animal (called the female).
Shell wandering describes the movement of
the male on the shell of the female. The male
moves from the point of boarding to the oppo-
site end of the shell and back, describing a
generally circular pattern, either clockwise or
counter-clockwise. The direction appears to
be random at first; but as shell wandering
progresses, a dextral male tends to settle into
a counter-clockwise pattern (Fig. 2), and a
sinistral male tends to move clockwise. As the
male enters the /ip quadrant (that section of
the shell bounded by the lip, the suture, and
the midline), the penis is everted. At this time
the male may pass his head or his penis along
the edge of the shell, a movement that we
have called testing the lip. During these
events the female moves toward the top of the
mating chamber and either remains stationary
or moves slowly in half or quarter turns.

A typical sequence of events is as follows.
As the male approaches the female there is
usually some body contact, often involving the
tentacles. The male then mounts the shell of

FIG. 3. An ideogram of shell wandering during
Early Courtship of P. taeniata.

the female at any convenient place and be-
gins shell wandering (Fig. 4a, c). Whenever
the circling motion brings him into the /р
quadrant, the penis begins to appear, reach-
ing its full extension as the male passes the
center of the lip. At this point he may test the

PARTULA COURTSHIP 135

FIG. 4. Courtship of P. suturalis of like coil. Sinistral: (a) Early Courtship: shell wandering, with male (X) at
the lip moving into a hanging position. (b) Late Courtship: probing, penis (arrow) near genital aperture of the
female. Dextral: (c) Early Courtship: shell wandering, with male (X) moving in counter-clockwise direction, (d)
Late Courtship: probing, penis (arrow) at rear of foot of female. (e) and (f) Copulation: two views showing the
position of head, tentacles, and penile bridge (arrows).

136 LIPTON AND MURRAY

lip and then turn away to continue wandering.
The female climbs to the top of the chamber
and proceeds along a crooked course.

Late Courtship. Late courtship is defined by
the assumption of the hanging position or
head-aligned position by the male. The male
commences probing of the female with the
everted penis. In the hanging position the
male is positioned so that his foot is parallel to
the lip and his head is projected slightly over
the lip of the shell of the female. In the head-
aligned position the male is at the center of
the lip with his head and foot parallel to that of
the female. Probing consists of a series of
stroking, swirling, or jabbing movements
made by the extended penis directed toward
the skin of the female. The probes are direct-
ed toward the foot, body stalk, or head/genital
aperture and are powerful enough to leave
temporary indentations on the skin.

Other movements made in late courtship by
the male or female include biting, head en-
twining, kissing, shell twirling, and head
prodding. Both partners may engage т bit-
ing. The male bites along the head, body
stalk, or foot of the female, The female bites
the head or foot of the male. The bitten animal
reacts suddenly by pulling or turning away or
by retracting into the shell. In head entwining
the heads of the male and female touch and
encircle one another. During this movement
kissing, consisting of mutual mouth contact
and visible working of the radulae, may occur.
Kissing differs from biting in that no sudden
reaction occurs. Shell twirling is a movement
by the female involving a clockwise and
counter-clockwise rotation of the shell, the
foot remaining stationary. Head prodding, by
the male, occurs when he is along the lip and
consists of pushing his head into the aperture
between the shell and body of the female,
thus prodding her body stalk or the side of her
foot.

In a typical late courtship, the male moves
along the lip into the hanging position and
commences probing (Fig. 4b). The everted
penis is placed on the female for several
seconds, lifted slightly, and then replaced.
After two to five seconds of concentrated
probing, the male usually lifts the organ higher
and retracts it slightly. Then probing resumes.
The entire bout of probing may last as long as
20 minutes at a time, with every exposed por-
tion of the female receiving attention (Fig. 4d).
After the bout, the penis is retracted, and the
male returns to shell wandering. As he
reaches the /ip quadrant, the penis is everted;
and he may begin another bout of probing or

continue shell wandering. The numbers of
wanderings and probing are quite variable.
Occasionally the male will move into the
head-aligned position, probing closer to the
genital region. Biting and head entwining
may occur at any time during late courtship.
Head prodding and kissing are rarely ob-
served.

During late courtship the female is not whol-
ly passive. She often moves in slow C- or S-
shaped turns (Fig. 4b). She may bite the male
or twirl her shell. She may turn her head to
engage in head entwining. During the most
intense probing, she curves her foot so that
the genital aperture is at the top of the curve.

The series of late courtship movements
may be repeated many times until copulation
occurs.

Copulation. At some point during the prob-
ing, the tip of the male organ is inserted into
the female tract (Fig. 4f). The penis becomes
thinner and more transparent. A more opaque
white “thread” (probably the penis retractor
muscle) within the organ can be seen to ex-
tend from the male to the female. Pulsations
along the penis can be seen. At this stage the
animals are stationary with tentacles with-
drawn, and they may be partially retracted
into their shells. The male is in the hanging
position. The female arches her head off the
substrate to curl it around the head or penis of
the male (Fig. 4e, f). Copulation persists for 5
to 65 minutes.Then the white thread can be
seen to be withdrawn first, followed by the
penis itself.

Reversal. The male dismounts and the two
animals separate. Sex roles may then be
reversed and courtship may resume. The
second courtship is almost as long as the first
and follows the same course leading to copu-
lation.

Comparative Mating Behavior

Wild and Laboratory Reared Animals. The
mating behavior of animals reared in the labo-
ratory was indistinguishable from that of
snails obtained from the wild.

Single Pairs and Group Trails. Courtship
patterns in group trials did not differ from those
exhibited by single pairs. The principal effect
of the group trials was that courting pairs were
often disturbed by other animals. This led to
the formation of mating chains involving three
to five animals (Fig. 6a). Common chains in-
cluded two males courting one female, or a
male courting the male of another pair. If two
males court one female, then there is compe-

PARTULA COURTSHIP 137

FIG. 5. Courtship of a dextral by a sinistral P. suturalis. (a) and (b) Early Courtship: shell wandering. (a) The
sinistral male moves to the apex from the lip. (b) The same male describes a clockwise circle by continually
turning right and is shown returning to the umbilicus rather than the suture of the shell. (c) through (f) Late
Courtship: probing. (c) Sinistral male at umbilicus probing the left side of the female. (d) Female adjusts shell,
shifting the male closer to the genital aperture on right. (e) Female repositions male by turning her head. (f)
Female turns her head and shell to place the male closer to her right side.

138 LIPTON AND MURRAY

tition for the correct probing position; and one
male is usually displaced toward the umbilicus
where he may continue to probe. Eventually one
male dismounts, either the original male or
the intruder. If a male begins to court an ani-
mal that has already begun courtship as a
male, then the latter usually reverses roles
and behaves as a female.

In the group trials all animals had been in-
duced to aestivate, but half the animals in
each trial had been individually isolated. The
subsequent trials showed no great disparity
between isolated and non-isolated animals,
although there is a suggestion in the data that
isolated animals tend to assume the role of
male.

Animals from Different Origins. Animals of
the same chirality from different valleys
showed no detectable differences in behavior.
Dextrals from Faataofe, Maramu, and labora-
tory broods had very similar courtships as did
sinistrals from Faatoai, Maharepa, and labo-
ratory broods. Courtship of dextrals was a
mirror-image of that of sinistrals. Each direct-
ed probing to the side of the head appropriate
to females of its own chirality, right for dextrals
and left for sinistrals.

Virgin and Non-Virgin Animals. No differ-
ence could be detected in the courtship of
virgin and non-virgin animals.

Courtship of Mixed Dextral and
Sinistral Pairs

Since chirality may function as an isolating
mechanism in nature, the behavior of dextral/
sinistral crosses in P. suturalis is of special
interest. That mating can occur has been es-
tablished by laboratory breeding (Murray &
Clarke, 1966, 1976b), but it appears that in
natural populations mating is not random with
respect to chirality (Clarke & Murray, 1969). In
these trials most of the animals were taken
from populations in which only dextrals or
only sinistrals are found. However, three ani-
mals were from polymorphic populations
(Faamaariri), and two were sinistral offspring
of dextral/sinistral crosses. Table 1 shows the
types of crosses, the mating activity, and the
elements of behavior that were displayed.

Foreplay. Pivoting and pursuit were carried
out as described above. The directions of the
C- and S-shaped turns were not related to the
type of coil of the animals.

Early Courtship. The predominating direc-
tion of shell wandering depends on the chiral-
ity of the courting male. Dextral males move in
counter-clockwise circles; sinistral males, in

clockwise circles. These movements lead the
male to approach the “wrong” side of the lip,
placing him near the umbilicus (Fig. 5a, b).

Late Courtship. The male continues court-
ship as if the female were of the same chiral-
ity. The hanging position of males in these
crosses was at the umbilicus. Probing was
directed to the side opposite the genital aper-
ture of the female (Fig. 5c). Shell wandering
separated bouts of probing.

The female in these trials was not passive;
she frequently turned her head and displayed
shell twirling, head entwining, and _ biting.
These movements appeared to be directed
toward aligning her genitalia with those of the
male (Fig. 5d-f).

Two late courtships were observed. Two
other pairs displayed many of the patterns of
courtship without probing. Copulation was
never witnessed in these trials.

In group tests, where four animals of each
coil were placed together, the opportunity for
dextral/dextral and sinistral/sinistral pairings
also existed. Of the 23 mountings that were
observed, 12 were between like pairs and 11
involved dextrals and sinistrals. Although the
numbers are small, there is no indication of
assortative mating.

Comparison with Monomorphic Trials.
From the mixed trials it appears that the be-
havior of the males does not differ from that
observed in monomorphic trials. The male
courts as if the female were identical to him-
self. The behavior of the femaie in mixed
trials, however, is different. She apparently
employs normal movements of courtship in a
special manner to facilitate copulation by the
male.

Partula taeniata
Description of Courtship

Of 22 trials conducted with P. taeniata, 17
produced useful results, the remainder show-
ing either complete inactivity (if so, trials were
terminated after 30 mintues) or random ex-
ploratory behavior (if so, trials were termin-
ated after 120 mintues). As in P. suturalis, the
description of the courtship of P. taeniata has
been divided into five stages: Foreplay, Early
Courtship, Late Courtship, Copulation, and
Reversal. Table 2 summarizes the behavioral
elements recorded in each of the stages.

Foreplay. Foreplay is defined by frequent
meetings and departures, dances, and pur-
suit. Mounting occurs often during meetings
but not during the dance. Dances consist of

PARTULA COURTSHIP 139

d ss

1 cm

FIG. 6. (a) Mating chain of P. suturalis. (b) through (e) Foreplay of P. taeniata. (b) Dance, showing turns by
both animals. (c) Dance, different view and type of turn. (d) Dance, pair touch side-by-side while passing. (e)

Pursuit.

LIPTON AND MURRAY

140

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PARTULA COURTSHIP 141

almost synchronous straight or curved move-
ments. As they approach each other, one
animal gently bumps the side of the other with
its head. The two then pass side to side,
touching shells as they pass. Pursuit consists
of circling turns made by one animal toward
another.

In a typical foreplay sequence, the pair ap-
proach, facing one another, and move into the
dance. Animal A approaches B diagonally. A
bumps B, and as they pass, their shells touch.
A then turns to follow B, while B also turns
toward A (Fig. 6b). Making C- and S-shaped
turns, the pair approach again (Fig. 6c). B
bumps A, and they touch shells in passing
(Fig. 6d). After a prolonged dance the pair
usually separate. One may follow the other in
pursuit (Fig. 6e). The pursuing animal may
mount the shell of the other. He then either
dismounts or proceeds to the next stage of
courtship.

Early Courtship. Early courtship is defined
by shell mounting followed by shell wander-
ing. In shell wandering the male moves
around the shell of the female in a figure of
eight pattern (Figs 2, 7a-e).

In a typical early courtship sequence, the
male mounts the shell of the female, usually
at the lip or the apex. Shell wandering follows,
bringing the male to the /ip quadrant (bound-
ed by the lip, the midline, and the suture). As
he moves toward the center of the lip, penis
eversion occurs. He may test the lip by pass-
ing his head or penis along the lip. Shell
wandering is then resumed. During this se-
quence of events the female usually climbs to
the top of the mating chamber.

Late Courtship. Late courtship begins when
the male assumes the head-aligned position
at the center of the lip (Fig. 7f) and begins
probing the head and genital area of the fe-
male. Figure of eight shell wandering usually
occurs before and after a series of probes
with the everted penis. The male may also
engage in biting, kissing, and head prodding.
The female may respond by biting, shell twirl-
ing, turning her head, or moving in C-shaped
turns. Head entwining or touching tentacles
involve both partners.

Touching tentacles takes place while the
male is in the head-aligned position. One
optic tentacle of the male and one of the fe-

FIG. 7. Courtship of Р. taeniata. (a) through (f) Early Courtship: shell wandering sequence describing a
figure of eight (X designates male throughout the sequence). (a) Male in head-aligned position. (b) Male
turning away toward apex of female shell. (c) Female has rotated her shell. (d) Male at apex of shell. (e) Male
has turned at the apex and moves toward the lip. (f) Male has returned to the head-aligned position and the
female curves her head. (g) Late Courtship: Probing. (h) Copulation.

142 LIPTON AND MURRAY

male touch, adhere briefly, and then separate.
The other terms are as defined in the descrip-
tion of late courtship in P. suturalis.

In a typical sequence, the male moves to
the center of the lip of the female and as-
sumes the head-aligned position. He everts
his penis and begins probing the head and
genital area of the female (Fig. 7g). The
movements vary from gentle strokes to strong
jabs and may be continued for a few seconds
to several minutes. After a bout of probing the
male resumes shell wandering that may ex-
tend to the apex as in early courtship or may
be confined to the body whorl of the shell.
Biting, kissing, and head prodding may ac-
company the principal movements.

The female is usually moving in slow C- and
S-shaped turns. She turns her head to pre-
sent her genital area to the male and may twirl
her shell and bite the male about the head
and everted penis. The pair may engage in
head entwining and touching tentacles.

Copulation. At some time during probing,
the male inserts the penis into the female
aperture (Fig. 7h). Copulaton is brief, averag-
ing only 75 seconds. During copulation both
animals retract their tentacles. The female
turns her head, arching over the male’s head
so that her mouth comes in contact with the
inserted penis. She bites the organ and the
top of the male’s head, often causing him to
retract into his shell, leaving only the penis
exposed. After copulation the male quickly
moves straight ahead off the shell. The fe-
male, her head still turned and arched, licks
her genital aperture, where a mucous secre-
tion is often seen.

Reversal. The female, after licking her
aperture, may follow and mount the departing
male and begin shell wanderng. Alternatively
the pair may separate and later undertake a
reversed courtship. Reversal was observed
following 13 of 33 successful copulations.
Once successful mating of both individuals
has occurred, courtship between the two
ceases. Even though they may subsequently
meet and briefly mount, no shell wandering
occurs. On the other hand multiple copulation
with several different animals is common.
During one observation period one individual
was observed to copulate with four different
animals. In another test one individual was
involved in four courtships with two animals,
behaving as a male and female toward each.
The two male courtships were unsuccessful,
the first female courtship resulted in a com-
pleted copulation, while the second female

courtship ended when a spermatophore was
extruded after copulation.

Comparative Mating Behavior

Wild and Laboratory Reared Animals. The
mating behavior of animals reared in the labo-
ratory was indistinguishable from that of
snails obtained from the wild.

Single-Pair and Group Trials. In group
matings the movements took place as in the
single-pair matings, but the timing was often
modified. With single pairs foreplay, especi-
ally the dance, was usual and often pro-
longed. In group matings this stage was ab-
breviated or absent.

In group trials mating pairs seemed to attract
other animals. The formation of mating chains
interfered with the courtship and prevented
reversal. Over all, single pairs were more
successful in bringing courtship to the point of
copulation.

Animals from Different Origins. No differ-
ences were detected in the courtship of ani-
mals from different valleys. Animals from
Faatoai, Faataofe, Faamaariri, and Maharepa
showed essentially the same behavior. Mat-
ings between animals from different valleys
did not show any unusual features. In mixed
group trials there was no detectable tendency
for snails of the same origin to mate preferen-
tially with one another. However, the data do
not permit statistical analysis since the obser-
vations are not independent.

Virgin and Non-Virgin Animals. There was
no apparent difference in the courtship of vir-
gins and non-virgins.

Comparative Mating Behavior of
P. suturalis and P. taeniata

The mating behavior of P. suturalis and P.
taeniata is very similar. The differences be-
tween the species are subtle and are sum-
marized in Table 3.

The foreplay of both species includes meet-
ing, mounting, and circular turns involving
body contact. The timing, however, is differ-
ent. Pivoting in P. suturalis involves sequen-
tial turns, while the dance of P. taeniata con-
sists of almost simultaneous movements.
Body contact is always sidelong in P. taeniata
but is variable in P. suturalis. Shell mounting
does not occur during the dance of P.
taeniata.

The shell wandering movements of the two
species in early courtship are rather different.

PARTULA COURTSHIP 143

TABLE 3. A comparison of the elements of courtship
in Partula suturalis and P. taeniata.

P. suturalis

P. taeniata

Foreplay:
1. Timing of move-

ments Sequential Simultaneous
2. Body contact Variable Sidelong
3. Shell mounting Present Absent in dance
Early Courtship:
1. Shell wandering Circular Figure of eight

2. Penis eversion Atumbilicus At center of lip

Late Courtship:

1. Probing Entire body Genital aperture and
top of head
2. Touching tentacles Absent Present
Copulation:
1. Duration Long Short
2. Female activity Passive Actively bites
3. Post-copulatory
licking Absent Present
Reversal: Delayed Rapid

P. suturalis follows а generally circular
pattern; P. taeniata moves in a figure of eight.
Penis eversion occurs later in P. taeniata be-
ginning only when the male arrives at the
center of the lip.

The probing in late courtship differs in de-
tail in the two species. P. suturalis probes the
foot, head, genital area, and body stalk of the
female, gradually concentrating on the genital
aperture. P. taeniata directs its probing much
more to the genital aperture and the top of the
head. The female controls the area to be
probed by revolving her shell (and hence the
male). P. taeniata seems to require more pre-
cise alignment before it begins probing.

Copulation differs in the two species mainly
in duration. In P. suturalis copulation has
been observed to last for up to 65 minutes,
but the longest duration for P. taeniata was 2
minutes. In addition, the female of P. taeniata
is more active during copulation, biting the
penis and head of the male. The post-copula-
tory licking of the genital aperture has only
been observed in P. taeniata. Separation and
subsequent meeting is usual in P. suturalis.

DISCUSSION
Relation to Courtship in Other Pulmonates

In most of the stylommatophoran pul-
monates that have been studied so far, court-
ship and copulation are reciprocal, both ani-
mals acting as males and females at the
same time (Fretter & Graham, 1964). The

non-reciprocal mating behavior of Partula is
therefore unusual in at least two significant
aspects: role recognition and reversal.

By the time that early courtship has begun,
separate male and female behavior patterns
have become apparent. The results of this
study suggest that the events of foreplay are
important in the establishment of these roles;
and that if the differentiation is not success-
fully accomplished, courtship is broken off.
Four lines of reasoning support this hypothe-
sis.

First, prolonged foreplay is common in sin-
gle-pair trials when partners have been iso-
lated for a long time. Since the chance of an
animal encountering an animal of opposite
tendency is reduced in single-pair as op-
posed to group trials, and since there is a
tendency for isolated animals (at least in P.
suturalis) to behave as males, the extended
foreplay can be interpreted as the result of
trying to resolve the problem of similar inclina-
tion.

Second, the behavior of two individuals in
foreplay is essentially the same. Moreover it is
similar to that of other stylommatophorans
with reciprocal courtship. The series of turns
so typical of foreplay in Partula has also been
described by Webb for numerous species
(1954a, Ashmunella; 1942, Helminthoglypta;
1948b, Stenotrema; 1952a, Monadenia;
1952b, Cepolis). Gerhardt (1933, 1934, 1935)
used the term Kreis to describe the turning
movements of the Vorspiel in the slugs Limax,
Agriolimax, and Arion. The animals form cir-
cles, break out of them, and then reform the
circles. Herzberg & Herzberg (1962) mention
a preliminary maneuvering stage before the
courtship of Helix aspersa. The similarity of
foreplay in Partula to the early stages of recip-
rocal courtship in other pulmonates suggests
that at this stage sexual roles are not yet de-
termined. What the proximate factor causing
the differentiation could be remains to be dis-
covered.

Third, foreplay may be abbreviated or ab-
sent from the courtship of Partula. Many pairs
proceed directly to early courtship, suggesting
that when role differentiation is already estab-
lished, foreplay is unnecessary.

Finally, pairs often break off contact after
foreplay, suggesting that the problem of dif-
ferentiation has not been resolved.

Once sexual roles have become estab-
lished during foreplay, the behavior of the two
animals in a non-reciprocal courtship is very
different. The male is considerably more ac-
tive than the female. The difference becomes

144 LIPTON AND MURRAY

apparent when the male mounts the shell of
the female and begins shell wandering and
probing.

Shell mounting appears to be an important
element of non-reciprocal courtship and is
found whenever this type of behavior occurs
(Strophocheilus, Wiswell & Browning, 1967;
Oreohelix, Webb, 1951; Lymnaea, Barraud,
1957). In contrast, partners engaging in re-
ciprocal courtship approach one another
head-on with both animals on the substrate
(Fretter & Graham, 1964).

The movements of shell wandering, so
prominent in early and late courtship, prob-
ably function in orientation. After mounting the
shell the male explores its surface in order to
align himself with the genital aperture of the
female. Then after a period of probing during
which he changes his position on the lip, a
reorientation becomes necessary. Similar
movements are performed by other pulmon-
ates with non-reciprocal courtships (Oreo-
helix, Webb, 1951; Lymnaea, Barraud, 1957).
In reciprocal courtship, reorientation on the
substrate is accomplished by what appear to
be the same sorts of movements (Ashmunel-
la, Webb, 1954a; Monadenia, Webb, 1952a;
Helminthoglypta, Webb, 1942; Cepolis,
Webb, 1952b).

Probing appears to have a dual function.
Probes directed toward the genital aperture
probably serve to orient the penis to the open-
ing of the female. Probing is also stimulatory.
In other pulmonates this stimulation may be
accomplished with the penis itself, as in
Partula (Strophocheilus, Wiswell & Brown-
ing, 1967; Lymnaea, Barraud, 1957), or with
special stimulatory organs (Arion, Meisen-
heimer, 1921; Cepaea, Taylor, 1914). Some
doubt has been cast on the role of these or-
gans by the work of Lind and Jeppeson. They
have pointed out that successful courtship
often takes place in Helix pomatia without the
discharge of the love dart (Lind, 1976) and
even after complete extirpation of the dart sac
(Jeppeson, 1976). Lind (1976) suggests that
while the firing of the dart may be stimulatory
to the actor it may even inhibit the recipient.
This interpretation supports their general
thesis that mating behavior in Helix is not a
series of reflex responses. Instead it is driven
by an internal program that is subject only to
orientation and synchronization by the part-
ner’s behavior (Lind, 1976; Jeppeson, 1976).

One component of male behavior in Partu-
la, testing the lip, appears to be unique. We
suggest that the function of this movement is

to detect whether the prospective partner is
adult, since the reflected lip only develops
with the attainment of sexual maturity. Dis-
sections show that the internal genitalia are
immature prior to the development of the re-
flected lip.

The role of the female in the non-reciprocal
mating pattern is generally passive. In Partula
the usual female response during courtship is
her movement to the top of the mating cham-
ber. In nature we have observed P. taeniata
courting on the underside of leaves up to two
meters from the ground. Climbing during
courtship has also been observed in nature for
Limax (Gerhardt, 1933) and in the laboratory
for Monadenia (Webb, 1952a), Mesodon
(Webb, 1954b), and Cepolis (Webb, 1952b).

Both male and female partners engaged in
mouth movements. The mouth contacts take
two forms, biting and kissing, both of which
are probably stimulatory. Radular biting
seems to be common among pulmonates
(Helix, Meisenheimer, 1907; Lind, 1976;
Triodopsis, Webb, 1948a; Oreohelix, Webb,
1951; Monadenia, Webb, 1952a; Ashmunel-
la, Webb, 1954a; Mesodon, Webb, 1954b).
Mutual lip contact is not as frequently ob-
served but does occur (Helix, Lind, 1976).

Two reciprocal elements present in non-
reciprocal courtship are head entwining and
retraction of the tentacles at copulation. Al-
though the significance of head entwining is
unknown, it does occur in other pulmonates
(Helix, Meisenheimer, 1921; Haplotrema,
Webb, 1943). Retraction of the tentacles by
both partners has also been observed fre-
quently (Helix, Szymanski, 1913; Limax,
Adams, 1898: Monadenia, Webb, 1952a;
Cepaea, personal observation).

The presence of a mucoid secretion after
copulation has been noted in Limax (Adams,
1898), Monadenia (Webb, 1952a), Cepolis
(Webb, 1952b), and Lymnaea (Barraud,
1957). In Limax as in Partula the secretion is
eaten.

Non-reciprocal courtship requires not only
the existence of separate roles, but also their
reversal. If both animals of a pair are to re-
ceive sperm they must at some time change
the nature of their roles. Reversal has also
been reported for other snails with non-re-
ciprocal behavior (Lymnaea (Barraud, 1957;
Polygyra, Archer, 1933).

Overall, the courtship of Partula is most
similar to that of Lymnaea (Barraud, 1957). In
Lymnaea there are also two probing positions
very similar to the hanging and the head-

PARTULA COURTSHIP 145

aligned positions of Partula. Since Lymnaea
is rather distantly related to Partula, the close
similarity is probably due to convergence.

Courtship as an Isolating Mechanism

Although many of the elements of the mat-
ing behavior of Partula are found in other
pulmonates, Partula courtship is distinctive. In
addition there are subtle differences between
the behavior of P. suturalis and P. taeniata.
The two species differ in the form of dancing
and pivoting, in the pattern of shell wander-
ing, in the location of probing, and in the dura-
tion of copulation. The next stage in the study
of these species will be to determine whether
these differences are of sufficient magnitude
to account for the reproductive isolation be-
tween the species in nature.

The mirror-image differences in the be-
havior of dextral and sinistral P. suturalis are
of particular interest, since the distribution of
these forms in nature suggests that chirality is
related to interspecific reproductive isolation
(Clarke & Murray, 1969). Mixed pairs are cer-
tainly capable of crossing and producing via-
ble, fertile offspring (Murray & Clarke, 1966,
1976b). Nevertheless there appears to be
some degree of assortative mating in natural
populations (Clarke & Murray, 1969). The be-
havioral studies have shown that this may
result simply from the disturbing effects of
reversed courtship. Successfu! copulation be-
tween mixed pairs was not observed in this
study.

In one respect our results may not be typi-
cal of mixed courtships in nature. Most of the
animals were derived from populations that
are either wholly dextral or wholly sinistral. It
is possible that courtship and copulation
might have been more successful if more ani-
mals from polymorphic populations had been
used. However, since those populations that
coexist with closely-related species are nor-
mally monomorphic for the opposite coil, it is
likely that mating behavior is a factor in en-
forcing reproductive isolation between spe-
cies.

ACKNOWLEDGEMENTS

We are especially grateful to Bruce H.
Lipton for his expert assistance in the prepa-
ration of the photographs. Betty Kater and
Lucy Parks kindly aided in the care of the ani-
mals. Elizabeth Murray and Irwin Konigsberg

have provided constant encouragement. The
authors thank Dietrich Bodenstein for the fa-
cilities he provided. This work was supported
in part by grant GB-4188 from the National
Science Foundation.

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146 LIPTON AND MURRAY

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MALACOLOGIA, 1979, 19(1): 147-155

AN ANALYSIS OF COPULATION IN BULINUS (PHYSOPSIS) GLOBOSUS
(GASTROPODA: PLANORBIDAE)!

Paul H. Rudolph?

Museum of Zoology, The University of Michigan, Ann Arbor, Michigan 48109, U.S.A.
and

Department of Zoology, Ain Shams University, Cairo, Arab Republic of Egypt

ABSTRACT

Copulation in Bulinus (Physopsis) globosus is unilateral, one member of a pair acting as male
only and one acting as female only during a single mating. Copulation usually lasts 40-90
minutes. Pre-insertion stages, from the time a male has attached to the shell of the female until
the insertion of the ultrapenis, account for 21.2% of total copulatory time. The ejaculatory period,
from the time of insertion of the ultrapenis until withdrawal, accounts for 69.7%, and post-
withdrawal stages, from withdrawal of the ultrapenis until the male leaves the female's shell,
account for 9.1% of total copulatory time.

Sperm are placed at the posterior end of the uterus, at the outlet to the oviduct, and can reach
the carrefour region while the snails are in copula. A copulatory plug, which contains entrapped
sperm at its posterior end, is found to fill the uterine lumen following copulation. The copulatory
plug and sperm are removed from the uterus to the spermatheca three to five hours following
copulation. The plug is of “springy” consistency and does not prevent insertion or insemination of
the plug-containing female by a second male.

INTRODUCTION

Sexual reproduction in many freshwater
pulmonates may occur by either self- or
cross-fertilization. Although many freshwater
pulmonates can reproduce by self-fertiliza-
tion, the preference for allosperm over auto-
sperm is well documented in studies using
genetic markers (e.g., Cain, 1956; Wu, 1972;
Richards, 1973). Cross-fertilization involves
copulation, and there have been a number of
studies describing in some detail aspects of
copulation of various freshwater species (de
Larambergue, 1939; Noland & Carriker, 1946;
Malek, 1952; Horstmann, 1955; Barraud,
1957; Boray, 1964; Pace, 1971).

Bulinine vector snails of human schisto-
somiasis have not been studied intensively in
regard to copulation, however. Some aspects
of copulation have been shown for Bulinus
contortus (= truncatus) (Brumpt, 1928; de
Larambergue, 1939), and Kuma (1975) has
given an overview of copulatory behavior for
Bulinus (Physopsis) globosus. Bulinine snails
are particularly interesting with regard to
copulation because of the copulatory organ,
which, due to the structural differences from
the copulatory organs of other freshwater

snails, is termed an ultrapenis (Hubendick,
1955). The method of eversion of the ultra-
penis is described for a number of bulinine
species (de Larambergue, 1939; Hubendick,
1948; Demian, 1960; Wu, 1972).

Sperm exchange, although important, may
not be the only function of copulation in fresh-
water pulmonates. It has been suggested that
snails which have acted as females will ovi-
posit at a younger age than isolated (i.e., self-
fertilizing) snails (e.g., Boycott et al., 1930;
Noland 8 Carriker, 1946; DeWitt, 1954;
Horstmann, 1955; DeWitt & Sloan, 1958,
1959) and that copulatory plug formation and
inducement of reciprocation are other aspects
of the copulatory act (Rudolph, 1979).

The present study examines two aspects of
copulation in Bulinus (Physopsis) globosus
(Morelet), copulatory behavior and copulatory
plug formation, in order to begin determina-
tion of the role of copulation in the sexual re-
production of this important snail vector of
Schistosoma haematobium.

MATERIALS AND METHODS

Albino Bulinus (Physopsis) globosus snails
were used from stocks maintained at The Uni-

ÎThis study was supported, in part, by a grant from the Smithsonian Institution (International Programs), Washington, D.C.,

U.S.A., to J. B. Burch.

2Present address: Museum of Zoology, The University of Michigan, Ann Arbor, Michigan 48109, U.S.A.

(147)

148 RUDOLPH

versity of Michigan and at Ain Shams Univer-
sity, Cairo, Arab Republic of Egypt. The pa-
rental snails of these stocks were collected in
Lourenço Marques, Mozambique, and main-
tained in laboratory culture since 1960. Snails
were raised in community, but were isolated
for at least one day prior to observation of
copulation. Snails were normally placed to-
gether in pairs, but occasionally three or four
were placed together.

Paraffin sections were made of reproduc-
tive tracts during and after copulation of snails
which acted as females. Two pairs of snails in
copula were killed by immersion in boiling wa-
ter, the ultrapenis of the male-acting snails
severed, and the reproductive tracts of the
female-acting snails dissected out and fixed.
Reproductive tracts of other female-acting
snails were removed and fixed at 0, 15 and 30
minutes and two, three, four and five hours
following copulation. Tissues were fixed in
Heidenhain’s Susa, dehydrated and cleared
in ethyl alcohol and xylene and embedded in
paraffin. Sections were made at 6 um and
stained with hematoxylin-eosin. Other obser-
vations were made by dissection of live snails.

Voucher specimens were deposited in the
Museum of Zoology, The University of Mich-
igan. Shell specimens are UMMZ 250035,
and alcohol specimens are UMMZ 250036.

RESULTS

Freshwater pulmonate snails are herma-
phroditic, and are capable of acting as either
male or female or both. The term male will
hereafter refer to the male-acting snail and
the term female to the female-acting snail.

The timed intervals for the copulatory
phases reported below, unless otherwise
stated, were determined at water tempera-
tures of 20-22°C and are from copulations in
which insertions of the ultrapenis occurred.
Timed observations were made at other tem-
peratures and observations were also made
during copulations which were not timed.
Copulation occurred at water temperatures of
16-25°C, but no attempt was made to ob-
serve below or above these temperatures.
Not all phases were observed on all copula-
tions, many times due to unfavorable position-
ing of the snails.

Copulatory behavior

Crawling on shell to initiate copulation.
After reunion into pairs, the interval between

reunion and the first crawling by the male on
the shell of the female which led to copulation
ranged from 10 to 131 minutes (n = 20, mean
= 47.9, S.D. = + 32). The male attaches di-
rectly to the female’s shell without any court-
ship. Crawling on shells which did not lead to
copulation was frequently observed, and
union into pairs did not always lead to copula-
tion. Snails would also twist or pivot the shell,
sometimes violently, when another snail at-
tached, in apparent attempts to prevent at-
tachment. This twisting did not discourage a
male which was to copulate. The male held
on, and the female soon stopped the twisting
motion.

Moving into position. After attaching to the
female’s shell, the male moves to the copula-
tory position. The male may move over the
female’s shell in a circular manner from the
female’s right to left, or may move directly to
the copulatory position. This, in part, depends
on whether first contact with the female’s shell
is made at the anterior or posterior end, or
from the side. Final movement to the copu-
latory position is always from the apex of the
shell toward the aperture. Thus a male attach-
ing to the female’s shell at the anterior end will
move to the apex and then slowly crawl ante-
riorly on the left side to the copulatory position.
However, a male attaching to the apex of the
shell may move directly to the copulatory posi-
tion or may circle in the above manner. The
interval from the time of first male crawling
to its assumption of the copulatory position
was two to eight minutes (n = 13, mean = 4.3,
5.0. = = 1.6):

The position of the male is at the left margin
of the female’s shell, its head at the level of the
female pseudobranch and the posterior end
of the male foot generally overlapping the
apex of the female’s shell. The male holds
tightly to the shell with its compacted foot (see
Figs. 3 and 4).

Preputial bulge. The first bulge of the
preputium occurs after the male is in the
copulatory position (Fig. 1). The interval after
having moved into position was less than
three minutes (n = 14, mean = 1.8, S.D. =
+ 0.9). In many cases the preputial bulge oc-
curred in less than one minute.

Preputial eversion. First eversion of the
preputium (Fig. 2) is also relatively rapid, tak-
ing three and one-half minutes or less (n =
16) from the time of appearance of the bulge.

Preputium under female's shell. Total ever-
sion and placing the preputium under the
shell of the female is generally a continuous

COPULATION IN BULINUS GLOBOSUS 149

%

- 7

FIGS. 1-4. Phases of copulation of Bulinus (Physopsis) globosus. All figures are to the same scale. Fig. 1.
Preputial bulge (arrow) after the male is in the copulatory position. Fig. 2. First eversion of the preputium
(arrow). Fig. 3. Preputium under the shell of the female before insertion; ultrapenis visible through the
preputial wall (arrow). Fig. 4. Ejaculatory stage; after insertion of the ultrapenis.

150 RUDOLPH

motion. The interval between the beginning of
eversion and placing the preputium under the
female's shell is two minutes or less (п = 15).

In many instances the first eversion was an
unmeasurable continuation of the bulge, or
the total eversion and placing the preputium
under the shell was a continuation of the first
eversion. The total time from preputial bulge
to placing the preputium under the shell was
less than four minutes (n = 15, mean = 2.1,
5.0: == 09):

Ultrapenis insertion. After the ргерийит is
placed under the female’s shell, the male
proceeds to insertion. Insertion was judged to
have occurred when the ultrapenis, visible as
a white stripe through the preputial wall, dis-
appeared and the preputium became round-
ed and light red, in contrast to the broad, flat-
tened, dark red preputium exhibited prior to
insertion (Figs. 3 and 4). The interval from
placing the preputium under the female's shell
to insertion was from 2 to 20 minutes (n = 21,
mean = 6.8, S.D. = + 5.5). Other observa-
tions showed that even longer times may be
required (up to 103 minutes) or that insertion
may never be successful. Extended periods
with everted preputia were usually associated
with retraction and re-eversion of the preputi-
um, and probing motions, and it was fairly
obvious that the male was having difficulty
with insertion. Moving out of the copulatory
position and back can also occur.

While the ultrapenis is inserted, the male is
tightly attached to the female’s shell, and the
male’s tentacles are contracted and often
slightly crossed. The male's preputium loops
ventral to the female’s extended pseudo-
branch (Fig. 4). During the period that the
ultrapenis was inserted, the female usually
did not move or moved only slowly, but rapid
gliding movement by females also occurred.

Withdrawal. Withdrawal was determined by
the reappearance of the ultrapenis and im-
mediate removal of the preputium from the
genital pore of the female. The interval be-
tween insertion and withdrawal was 24 to 63
minutes (п = 21, mean = 38.6, SD. =
11:6).

Moving off copulatory position. After with-
drawal, the preputium is inverted and the
male usually moves from the copulatory posi-
tion. The interval from withdrawal to the first
movement from the copulatory position for 17
snails was one-half to five minutes (mean =
3.2, S.D. = + 1.2). Two other males re-
mained in the copulatory position for an ex-
tended time period (28 and 40 minutes), and

two further males remained in position 136
and 139 minutes and then reinserted their
ultrapenes. Remaining in the copulatory posi-
tion for an extended time was observed in
non-timed copulations as well. Preputial bulg-
ing and eversion could occur during these ex-
tended periods, in addition to the reinsertions
described above.

Copulations in which the male remained in
the copulatory position as stated above were
at first considered as unsuccessful copula-
tions. However, subsequent dissection or
sectioning of two females from copulations in
which the male remained in position but did
not, or was not allowed, to reinsert showed
sperm and other material present in the fe-
male reproductive tract of the female.

Moving off shell. After the first movement
from the copulatory position by the male, it
usually moves directly off the shell of the fe-
male. After the male has left the female’s
shell, it shows no further interest in the fe-
male. The interval for 16 snails to move from
the shell after moving from the copulatory po-
sition was one to six minutes (mean = 2.8,
S.D. = + 1.7). Another snail stayed on the
shell 19 minutes. Two other maies moved
back into the copulatory position and re-
mained there for 107 and 144 minutes and
then were removed. It is possible that a male
could remain longer than 144 minutes, since
this snail was removed forcibly and the ex-
periment terminated.

Inversion of roles. Copulation in which the
female acted as male to either the male or a
third snail occurred in three cases of 44 copu-
lations observed at all temperatures. Others
occurred in non-timed observations. They al-
ways occurred after the male had moved from
the female’s shell. In the timed observations,
intervals from the departure of the male until
the female crawled onto the shell to initiate
copulation were two, 23 and 42 minutes.
Males can act as females after acting as
males.

Female receptivity. In non-timed observa-
tions, it was seen that the failure of the male to
copulate successfully can be due to the fe-
male (also see Second Copulations, below).
The female behaved in two ways to prevent
successful insertion by the male—by holding
its shell tightly against its body and by using
its foot to fill the aperture of the shell. The
female, in the latter case, turned its foot
around so that the head region was in the
posterior region of the aperture. The male
could not place its extended preputium near

COPULATION IN BULINUS GLOBOSUS 151

the female’s genital pore, and it also ap-
peared that the female actively repelled the
preputium of the male with its foot and head
region while in that position.

Summary of copulation in Bulinus (Phy-
sopsis) globosus. Copulaton is unilateral,
one snail acting as male and one as female
during a single meeting between two snails.
There is no reciprocation, although females
may be able to function as males shortly after
having functioned as females. Since nearly all
observations were made using only two
snails, there was little opportunity to observe
multiple unilateral copulations (i.e., chain
copulations, as defined by Rudolph, 1979).
However, | have observed chain copulations
by these snails in community aquaria.

Total time of copulation is considered to last
from the time the male crawled onto the fe-
male’s shell until the male departed. Five
copulations which showed extended pre-
insertion or post-withdrawal stages lasted 89,
190, 205+, 215+ and 231 minutes. However,
copulations usually did not show extended
pre-insertion or post-withdrawal stages. Such
copulations lasted 41-86 minutes (n = 13,
mean = 57.2, S.D. = + 13.1). Observations
of all stages in ten of these 13 copulations
showed that pre-insertion stages (from first
crawling until the ultrapenis was inserted) ac-
counted for an average of 21.2% of total
copulation time. The ejaculatory stage (from
insertion of the ultrapenis until withdrawal)
accounted for 69.7% of total copulation time,
and post-withdrawal stages for 9.1% of total
copulation time (Table 1).

Female Reproductive Tract of Female Snail

Sections and dissections showed that im-
mediately following copulation the female re-
productive tract of the female contained
sperm, situated at the posterior end of the
uterus, extending into the chambers of the post
oviduct (terminology of Walter, 1968) and the
oviduct. The uterine lumen also contains a
mass of material. This mass extends to the
vagina, filling the lumen of the uterus, and the
sperm in the uterus are captured or embed-
ded in the material of the mass (Figs. 5 and
6). The material forms a mass which is not
rigidly compact, but rather somewhat soft and
“springy” in consistency. Part of the material
which immediately surrounds the sperm is
basophilic, while the remainder is eosino-
philic. Dissections of females showed that the
material adheres somewhat to the uterine
walls.

Sperm were present at the level of the car-
refour region 30 minutes after insertion but
before withdrawal of the ultrapenis, as well as
in snails fixed immediately, 15 and 30 minutes
following copulation.

Sperm are passed to the female before the
mass of material found in the uterus, and are
deposited at the proximal end of the uterus
(ovotestis as reference point for proximal and
distal) at the outlet to the oviduct. It was not
determined whether any material is passed
along with the sperm.

The sperm and mass of material persist in
the uterus apparently unaltered for at least
two hours following copulation. By three hours

TABLE 1. Time and percentage of total time of the stages of copulation of Bulinus (Physopsis) globosus.

Pre-insertion Ejaculatory Post-withdrawal
m u — — Total time
Snail Minutes % Minutes % Minutes % minutes
1 9 22.0 28 68.3 4 9.8 41
2 14 33:3 24 57 a 9.5 42
3 7 15.9 31 70.5 6 13.6 44
4 7 14.6 33 68.8 8 16.7 48
5 13 26.5 33 67.3 3 6.1 49
6 13 24.1 39 72.2 2 3:7 54
7 11 18.3 44 73.3 5 8.3 60
8 15 22.1 48 70.6 5 7.4 68
9 15 21.7 48 69.6 6 8.7 69
10 15 17.4 63 73.3 8 9.3 86
Mean 11.9 39.1 5.1 56.1
S.D. + 3.2 a2 8 + 2.0 + 13.8
Mean % 21.2 69.7 9.1

152 RUDOLPH

FIG. 5. Diagrammatic dorsal view of the female
reproductive system of Bulinus (Physopsis) globo-
sus immediately following copulation. The surface
of the uterus has been removed to show the posi-
tion of the copulatory plug and sperm. Hatched
area represents the cut surface of the uterus. Ab-
breviations: AG = albumen gland; CP = copulatory
plug; GP = female genital pore; O = oviduct; P =
prostate; PO = post oviduct; S = sperm; SD =
sperm duct; U = uterus.

following copulation, the mass and associated
sperm have been displaced either anteriorly
into the vaginal region or are removed entirely
to the spermatheca. Reproductive tracts are
empty four and five hours following copula-
tion, and sperm and associated material are
recognizable in the spermatheca. In fact, no
sperm can be observed anywhere except in
the spermatheca at four and five hours.

The mass of material which fills the uterine
lumen is probably composed primarily of
secretions from the male reproductive tract of
the male snail, although participation by the
female reproductive tract of the female snail
can not be ruled out. The method of its re-
moval to the spermatheca is not clear.

Second Copulations

Females were allowed to be mated by a
second male to determine whether the mass

FIG. 6. Section of the uterus of a female Bulinus
(Physopsis) globosus immediately following copu-
lation. See Fig. 5 for abbreviations.

of material which fills the uterine lumen from
the first mating can function to prevent a
second copulation. Of seven attempts, three
males were completely unable to insert the
ultrapenis and moved off the female’s shell.
This lack of success was due, however, to
female non-receptivity as described above,
even though the female had been completely
receptive to copulation by the first male.
Three other males were able to insert their
ultrapenes but with difficulty, due to female
non-receptivity, and with extended phases
with everted preputia. These three were able
to insert at one, one and three-fourths and two
and one-half hours following the withdrawal
by the first male. One further snail met with no
resistance and was able to insert its ultrapenis
15 minutes following the first copulation.
These results indicate that insertion is not
prevented by the presence of the material
from a previous copulation plugging the
uterus.

Males, except the one which inserted one
hour following the first copulation, were al-
lowed to finish. Histological observations on
reproductive tracts of females from the sec-
ond copulations with insertion times of one

COPULATION IN BULINUS GLOBOSUS 153

and three-fourths hours and two and one-half
hours following withdrawal of the first male
showed evidence of two sperm groups, but it
could not be determined to which male part-
ner the sperm belonged. In both instances,
one sperm group was present at the oviducal
outlet and was organized as if it were recently
placed. The other group was not as well or-
ganized and was in the uterus and vagina,
distal to the above group of sperm. In the fe-
male in which second intromission occurred
15 minutes after the withdrawal of the first
male, the sperm groups appeared to be such
that one mass was at the outlet to the post
oviduct, the position sperm are normally
placed. The second mass was in the uterus,
close to the first mass and distal to it. The
female from the second copulation with inser-
tion one hour following withdrawal of the first
male was dissected approximately 20 min-
utes following insertion by the second male.
The ultrapenis of this second male was in the
normal position, inserted between the mass of
material in the uterus and the uterine wall.

The indications are that it may be possible
for the second male to ejaculate its sperm at
the proper position, especially one and one-
half to two hours following withdrawal of the
first male, since, by this time, the material in
the uterus from the first copulation may be
more easily moved than immediately after
copulation. Even in a second copulation
which occurred 15 minutes following with-
drawal of the first male, it is possible that the
first sperm group is pushed from its normal
position by the ultrapenis of the second snail,
which then placed its own sperm at the normal
position. It is not possible to determine the
relationships between two copulations in re-
gard to the contents of the uterus following the
second copulation, since it is not possible to
distinguish between the products of the two
copulations.

DISCUSSION

Copulation in Bulinus (Physopsis) globo-
Sus is found in the present study to be uni-
lateral, confirming the observation made by
Kuma (1975) on the same species. The pres-
ent behavioral observations show that the
stages prior to intromission and following
withdrawal of the ultrapenis are relatively
rapid. The longest phase is while the snails
are in copula, during which ejaculation of
spermatozoa and other material, presumably

composed of secretory products from the
male reproductive system of the male snail,
occurs. Unilateral copulation is shared by the
other bulinine snails Bulinus contortus (=
truncatus) and Pyrgophysa forskali (de
Larambergue, 1939).

Kuma (1975) also stated that copulation in
Bulinus (Physopsis) globosus lasted between
one and two hours. The present study shows
that copulation usually lasted from about 40 to
90 minutes, in general agreement with Kuma.
The objective of this study was to determine
the temporal relationships during copulation
in B. (P.) globosus. Of particular interest is
that even though a male could be in the copu-
latory position for extended periods, these ex-
tended periods were primarily in the phase
when intromission is attempted and in post-
withdrawal phases. The phase of insertion
appears to be the most critical. If insertion is
not effected, even after an extended period of
attempting insertion, the snail will move off the
shell and copulation will be unsuccessful. The
interval when the snails were actually in
copula was reasonably uniform, and after in-
tromission had occurred, ejaculation was
probably assured. This was also the longest
phase of copulation, undoubtedly due to the
importance of exchanging sperm and male
secretory products.

Details of copulation, such as unilaterality,
“coagulum” or plug formation and rapidity
with which the ejaculated sperm reach the
upper portions of the female reproductive
tract of the female, are very similar to that
which occurs in Bulinus contortus (=
truncatus) (de Larambergue, 1939).

The importance (to the snail) of the mass
found in the female reproductive tract of the
female is not entirely clear. Rudolph (1979)
has interpreted the mass found in the vagina
of Stagnicola elodes (Lymnaeidae) as a
copulatory or mating plug. A similar structure
to that of Stagnicola was described for
Lymnaea stagnalis (Horstmann, 1955) and de
Larambergue (1939) reported a mass in
Bulinus contortus (= truncatus) similar to the
one found in Bulinus (Physopsis) globosus.
Two functions which were ascribed to a
copulatory plug (Parker, 1970), prevention of
sperm leakage and prevention of a second
insemination of the same female by a second
male, appeared to be feasible for the plug in
Stagnicola.

Neither of these two functions appear likely
for the copulatory plug of Bulinus (Physopsis)
globosus. Due to the placement of the sperm

154 RUDOLPH

at the proximal end of the uterus at the outlet
to the post oviduct, sperm leakage from the
female gonopore appears to be unlikely. The
mechanism by which sperm are transported
to the carrefour region is not clear. Bulinine
snails do not contain a ciliated groove in the
oviduct as is found in lymnaeids. There does
not seem to be agreement as to whether the
oviduct contains any ciliation in bulinine
snails. Stiglingh et al. (1962) reported ovi-
ducal ciliation in B. tropicus and Hamilton-
Attwell & Van Eeden (1969) reported sparse
ciliation in B. depressus, but Wright (1957)
did not find cilia in the oviduct of B. (P.)
jousseaumei and | found none in B. (P.)
globosus in the present study. It is fairly clear
that if ciliation is present, it is sparse. If peri-
staltic muscular pressure or active movement
by the sperm themselves are mechanisms
which move the sperm through the oviduct in
B. (P.) globosus, it is possible that the plug
functions to prevent sperm leakage from the
oviduct itself, preventing backflow of sperm
ascending the oviduct into the uterus. How-
ever, sperm reach the carrefour before the
male has withdrawn, so sperm leakage ap-
pears to be of small concern.

A second function described for a copula-
tory plug, that of preventing successive copu-
lations or inseminations of the same female
by two different males, is not shown by the
plug of Bulinus (Physopsis) globosus. A
second successful insertion of the ultrapenis
and subsequent ejaculation of sperm can oc-
cur while there is plug material present in the
female reproductive tract of the female, even
as soon as 15 minutes following the first copu-
lation, possibly due to the rather soft con-
sistency of the plug. However, determination
of the origin of the sperm present in the fe-
male after two successive copulations was
not possible. The possibility still exists that the
passage into the oviduct is successfully
blocked and that sperm from the second
copulation cannot pass those from the first.
Thus, although successful insemination is
possible, successful fertilization may not be.
After clearing of the female reproductive tract,
of course, there appears to be no physical
barrier to the sperm of a second male. This
would imply that sperm which have reached a
storage site and are then left unprotected by a
copulatory plug may have some other advan-
tage over sperm which arrive later, if they are
to be used preferentially. The possibility also
exists that mixing of sperm from two males
could occur or that sperm from a later copula-
tion are used preferentially.

Whatever its function(s), the rapidity with
which the sperm reach the carrefour region
may be important in determining the effective
existence of a copulatory plug. Since sperm in
Bulinus (Physopsis) globosus can already be
at the carrefour region before the male with-
draws, the maintenance time of a plug may
not need to be as long as in a species in which
sperm are deposited in the vaginal region,
and thus proportionally have further to travel.
In Lymnaea stagnalis, for example, sperm
reach the carrefour region about two hours
after copulation (Horstmann, 1955), and the
effective existence of the copulatory plug of
Stagnicola elodes appears to be about two to
three hours (Rudolph, 1979).

It is probable that, in Bulinus (Physopsis)
globosus, the material found in the uterus has
other functions in addition to or instead of the
two mentioned above. Further studies in the
area of the fate of the sperm from a second
copulation, both while the uterus is full of
material and after it has been cleared, await
the use of genetic markers or radioactively
labeled sperm.

The present study is a basic step in evaluat-
ing the function of the male reproductive sys-
tem in Bulinus (Physopsis) globosus. Study
of sexual reproduction in freshwater snails
has long been weighted toward the female
reproductive system and its products, the
eggs, with good reason. However, studies on
the functioning of the male system and its in-
fluence on reproduction may yield insight into,
as yet, unexplored methods of snail control.

ACKNOWLEDGEMENTS

The author thanks Dr. J. B. Burch, The Uni-
versity of Michigan, for financial support and
Dr. Е. $. Demian, Ain Shams University,
Cairo, for laboratory space.

LITERATURE CITED

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COPULATION IN BULINUS GLOBOSUS 155

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MALACOLOGIA, 1979, 19(1): 157-199

ANATOMY OF CHIONE CANCELLATA AND SOME OTHER CHIONINES
(BIVALVIA: VENERIDAE)!

Carol C. Jones

Woods Hole Oceanographic Institution, Woods Hole, Mass. 02543, U.S.A.

ABSTRACT

Chione cancellata (Linnaeus), Chione undatella (Sowerby), and Chione paphia (Linnaeus)
are anatomically very similar, although their lineages diverged before the end of the Miocene.
Except for differences ascribable to greater size, Mercenaria mercenaria (Linnaeus) is in soft
anatomy similar to the smaller chionines. Mercenaria and Chione diverged by the Late Oligo-
cene; soft anatomy is fairly conservative. Austrovenus stutchburyi (Gray) of New Zealand,
although superficially similar to the cancellate American chionines, differs from them in com-
plex characters, and is probably not closely related to them. Lack of intermediate fossils supports

this interpretation.

INTRODUCTION

To begin to elucidate relationships among
genera assigned to the Chioninae (Keen,
1951, 1969), | examine the anatomy of five
common and fairly widespread species usu-
ally put in this subfamily of venerid bivalve
mollusks. Chione cancellata and C. undatella
represent the nominate subgenus on the
American Atlantic and Pacific coasts, respec-
tively. Caribbean C. papñia represents the
once-prosperous subgenus Panchione. The
fourth species usually aligned with Chione is
Austrovenus stutchburyi of New Zealand,
Pliocene to Recent. The large and commerci-
ally important American chionine, Mercenaria
mercenaria, lives on the eastern and Gulf
coasts, as well as in other parts of the world
where it has been introduced.

The contentions | particularly wish to ad-
dress are those of Frizzell and Marwick. In his
reclassification of the Veneracea, to which the
species discussed here belong, Frizzell
(1936) rejected classification based solely on
soft parts as inapplicable to fossils, and the
processes of obtaining this sort of information
as too costly and time-consuming. He further
stated that conchological characters and
character states are numerous enough to
provide the many combinations on which to
base a Satisfactory classification. He failed to

consider the point that combinations mathe-
matically possible might not be biologically vi-
able, and that certain highly adaptive combi-
nations may evolve in several different line-
ages in response to similar circumstances.
Marwick (1927) dismissed such conver-
gences as uncommon, “because so many co-
incidences are involved.” On the basis of shell
morphology, especially sculpture, Marwick
stated that Austrovenus stutchburyi of New
Zealand is closely related to American
chionines of both east and west coasts. | wish
to show that characters of soft anatomy and
shells, together with evidence from the fossil
record, do provide enough clues for the con-
struction of a phylogenetic classification
which can accommodate convergence т
shell characters.

MATERIALS

The numbers and provenance of speci-
mens dissected are herein listed. All were
sexually mature.

Chione (Chione) cancellata (Linnaeus): 1,
Bimini Lagoon, Bahamas; 3, western Virginia
Key, Biscayne Bay, Fla.; 8, Bear Cut, Virginia
Key, Biscayne Bay, Fla.

Chione (Chione) undatella (Sowerby): 9,
San Diego, Cal., Hassler Expedition.

1This paper is a revision of a chapter in a dissertation submitted in partial fulfillment of the Degree of Doctor of Philosophy in the
Department of Geological Sciences, Harvard University, Cambridge, Massachusetts.

(157)

158 JONES

Chione (Panchione) paphia (Linnaeus): 7,
Enseada das Palmas, Sao Paulo, Brazil.

Mercenaria mercenaria (Linnaeus): 8,
market; 1, Buzzards Bay, Mass.

Austrovenus stutchburyi (Gray): 7, Auck-
land Harbour, New Zealand.

METHODS

For most of this work | used an inexpensive
binocular microscope suitable for examining
relatively large objects; only occasionally had
| access to a dissecting microscope. Most
structures studied are, therefore, those visible
through a relatively poor optical system. Ex-
cept for Chione paphia, the animals were not
relaxed. Chione undatella, C. paphia and
Austrovenus stutchburyi were preserved in
80-90% ethyl alcohol; the other species were
preserved in commercial isopropyl alcohol.
Because they are believed useful in establish-
ing relationships (Ansell, 1961), and because
there is a body of literature about them, | pay
particular attention to the stomach and si-
phons. Lack of general information prompted
attention to the nervous system.

Unless otherwise indicated, the scale line
represents 1mm. Arrows point anteriorly.
Widely spaced canted lines indicate severed
edges. All shells are shown at the same scale.

KEY TO ABBREVIATIONS ON FIGURES

aa anterior aorta

ac anal canal

ad dorsal aorta

ата anterior adductor muscle
amp posterior adductor muscle
an anus

ap posterior aorta

at acceptance tract

au auricle

aum muscle fibres in auricle
ba bulbus arteriosus

bk beak

ca collecting area

cpc cerebropedal connective
ct connective tissue

cta anterior cardinal tooth
ctenidial axis

cic central cardinal tooth

ctp posterior cardinal tooth
CVC cerebrovisceral connective
dbi inner demibranch

outer demibranch

extension of outer demibranch
digestive diverticulum
digestive gland

dental platform

distal valve of excurrent siphon
escutcheon

foot

food groove

fenestra

cerebral ganglion

gonad

gonoduct

pedal ganglion

gonopore

gastric shield

subsidiary siphonal ganglion
visceral ganglion
intestine

interlocking ridge
interlocking slot

inner timb of kidney
outer limb of kidney
ligament

lunule

dorsal labial palp
longitudinal pallial muscle
ventral labial palp

mouth

anterior margin

dorsal margin

marginal denticle

first mantle fold

second mantle fold

third mantle fold

fourth mantle fold

midgut

opening into midgut
posteror margin

ventral margin

nerve to adductor muscle
nerve to body mantle
ctenidial nerve
nephridioduct
nephridiopore
nephrostome

nerve to labial palp
nerve to kidney

pedal nerve

anterior pallial nerve
anteroventral pallial nerve
posterior pallial nerve
posteroventral pallial nerve
pedal retractor nerve
nerve to excurrent siphon
nerve to incurrent siphon
nerve to shell mantle
siphonal retractor nerve

CHIONINE ANATOMY 159

nst nerve to statocyst

nvm nerve to anterodorsal visceral mass
ny nymph
oe oesophagus

oeg oesophageal gland (?)

orc commarginal ornamentation

orr radial ornamentation

Opening between stomach and diges-
tive diverticulum

рсс pericardial cavity

pfs partial flap over siphons

pgl pedal gland

pgld duct of pedal gland
pgls slit of pedal gland
por periostracal groove
pl pellicle

ри pallial line

pls pallial sinus

pit posterior lateral tooth

pm pallial muscle

prma anterior pedal retractor muscle
prmp posterior pedal retractor muscle
pvse proximal valve of excurrent siphon
pvsi proximal valve of incurrent siphon

$ stomach

sa sorting area

заа scar of anterior adductor muscle
sap Scar of posterior adductor muscle

se excurrent siphon
sh shelf of stomach
si incurrent siphon

sm shell mantle
SOC Supraoesophageal commissure

spra scar of anterior pedal retractor muscle

sprp scar of posterior pedal retractor
muscle

srm Siphonal retractor muscle

st statocyst

t tentacle

ty typhlosole

tyma major typhlosole

tymi minor typhlosole

vi valve between auricle and ventricle

vn ventricle

wc water chamber

wt water tube

PREVIOUS WORK

Although many workers have examined
details of its anatomy and physiology, Kellogg
(1910), Belding (1912), Woodruff (1938),
Miner (1950), Pierce (1950), and Barnes
(1974) offer only figures and slight discussion
of the general anatomy of Mercenaria
mercenaria or the quahog. Indeed, the same
figure, variously modified, appears in most of

these works. Carriker (1961) discusses fully
the larval and juvenile phases of the quahog;
О’Азаго (1967) and LaBarbera & Chanley
(1970) studied the development of larval
Chione cancellata, Moore and Lopez (1969)
its ecology, Paine (1963) its enemies. Stanley
(1970) comments on the burrowing habits and
functional morphology of many species, in-
cluding C. cancellata, C. paphia and M.
mercenaria. Dissections of several other
venerids are sufficiently detailed for compari-
son (Ansell, 1961; Nielsen, 1963; Narchi,
1972). Information on the anatomy of C.
undatella and A. stutchburyi is lacking. Brown
et al. (1956) studied cycles of activity in the
quahog, and Comfort (1957) listedthisclam as
living as long as 40 years (but see Farrow,
1972; Loesch & Haven, 1973). Particulars of
anatomy garnered from other works appear in
their due places.

Chione cancellata prefers muddy sand sta-
bilized by marine plants (McNulty, 1961;
McNulty et al., 1962) in the shallow subtidal
zone. Examination of Bird’s (1970) tables and
maps shows that this species tolerates salini-
ties as low as about 187/00. Chione cancellata
prefers sheltered embayments. It occurs from
about Beaufort, North Carolina southward to
about Rio de Janeiro, and in the Gulf of Mexico.
Chione paphia is occasionally found in the
Florida Keys, but is common in the Caribbean
and southward to southern Brazil. It lives in
clean gravelly carbonate sand without plants
at depths of about 10 to 55 fathoms (Stanley,
1970; Rios, 1970). Mercenaria mercenaria
lives in the intertidal and shallow subtidal
zones, buried in gravelly sand and gravelly
muddy sand (Stanley, 1970). The quahog
ranges from the Gulf of St. Lawrence to Flori-
da. Chione undatella lives in tidal creeks
(Macdonald, 1969) and in protected beaches,
from southern California to Payta, Peru
(Keen, 1971). Austrovenus stutchburyi usu-
ally lives in moderately firm sands in the shal-
low subtidal zone, although a few large ani-
mals live in soft flocculent muds; it prefers
embayments with fairly strong currents (Paul,
1966), and is uncommon in poorly aerated
sediments (Powell, 1937). It is found all
around New Zealand (Penniket, 1970). All are
shallow-burrowing suspension feeders. The
presence of polydorid polychaetes, plant at-
tachments, and even small corals on their
posterior margins shows that C. cancellata
and A. stutchburyi live not quite fully buried.
A. stutchburyi is often extensively eroded in
this area.

160 JONES

icm

FIG. 1. Chione cancellata, exterior of right valve. FIG. 2. Chione cancellata, interior of right valve. FIG. 3.
Chione cancellata, anterior end of left valve. FIG. 4. Chione cancellata, posterior end of left valve. FIG. 5.
Chione cancellata, interior of left valve. FIG. 6. Chione paphia, exterior of right valve. FIG. 7. Chione paphia,
interior of right valve. FIG. 8. Chione paphia, interior of left valve. FIG. 9. Chione undatella, exterior of right
valve. FIG. 10. Chione undatella, interior of right valve. FIG. 11. Chione undatella, interior of left valve.

CHIONINE ANATOMY

1cm

cte ctp plt

16

7
trs,

“un Mau
ns il
mdn R

161

FIG. 12. Austrovenus stutchburyi, exterior of right valve. FIG. 13. Austrovenus stutchburyi, interior of right
valve. FIG. 14. Austrovenus stutchburyi, interior of left valve. FIG. 15. Mercenaria mercenaria, exterior of

right valve. FIG. 16. Mercenaria mercenaria, interior of right and left valves.

162

JONES

18

FIG. 17. Muscle scars in venerid bivalves. FIG. 18. Chionine anatomy, shell removed.

Pon

CHIONINE ANATOMY

ae a
— —a
И N,
2 sm $ AA
= a; y
4 amp) Lon
рузе = Y
N srm = т 2; dvse

5 AA Gohl £ >
x à, eee Er +
N renee BUT

da,

a, \

EIN МАМУ - =>
И ee STAN

A m2

m
a mf4 Ipm

163

FIG. 19. Chionine anatomy, mantle and body wall removed. FIG. 20. Mantle of Chione cancellata.

164 JONES

el

FIG. 21. Midventral cross section of mantle edge, Chione cancellata. FIG. 22. Mantle of Chione paphia. FIG.
23. Mantle of Chione undatella. FIG. 24. Midventral cross section of mantle edge, Chione undatella.

CHIONINE ANATOMY 165

= 5mm

If
YA}

N

| AR

FIG. 25. Mantle of Austrovenus stutchburyi. FIG. 26. Dorsal edge of mantle, Austrovenus stutchburyi. FIG. 27.
Section of siphons, Austrovenus stutchburyi.

166 JONES

d

SU, И MAN NT Wi \

ЦИ NIN YANN \\ =
> U [AM AI {| Ni Wy —
= WR SW я pe

a Ре

23

28 aa

FIG. 28. Midventral cross section of mantle edge, Austrovenus stutchburyi. FIG. 29. Mantle of Mercenaria
mercenaria. FIG. 30. Midventral cross section of mantle edge, Mercenaria mercenaria.

CHIONINE ANATOMY 167

о 3
: 3

33

35

FIG. 31. Cross section of gill plica, Chione cancellata. FIG. 32. Cross section of gill plica, Chione undatella.
FIG. 33. Cross section of gill plica and structure of water tube, Austrovenus stutchburyi. FIG. 34. Cross
section of gill plica, Mercenaria mercenaria. FIG. 35. Labial palps of Chione cancellata. FIG. 36. Labial palps
of Chione paphia. FIG. 37. Labial palps of Chione undatella. FIG. 38. Labial palps of Austrovenus stutch-
buryi. FIG. 39. Labial palps of Mercenaria mercenaria.

168

JONES

44 45

FIG. 40. Digestive system, Chione cancellata. FIG. 41. Scheme of digestive system, Chione cancellata

FIG. 42. Digestive system, Chione paphia. FIG. 43. Scheme of digestive system, Chione paphia. FIG. 44

Digestive system, Chione undatella. FIG. 45. Scheme of digestive system, Chione undatella.

DI ke mer me an -

169

CHIONINE ANATOMY

47

49

51

FIG. 46. Digestive system, Austrovenus stutchburyi. FIG. 47. Scheme of digestive system, Austrovenus
em, Mercenaria mercenaria. FIG. 49. Scheme of digestive system,

stutchburyi. FIG. 48. Digestive syst
Mercenaria mercenaria. FIG. 50. Oesophageal glands (?) of Chione paphia. FIG. 51. Dorsal and ventral

aspects of oesophageal gland (?) of Chione undatella.

170 JONES

FIG. 52. Stomach, Chione cancellata. FIG.53. Stomach, Chione paphia. FIG. 54. Stomach, Chione unda-
tella. FIG. 57. Gastric shield, Chione undatella. FIG. 58. Gastric shield, Austrovenus stutchburyi. FIG. 59.
Gastric shield, Mercenaria mercenaria.

CHIONINE ANATOMY 171

3
Veg > E
EL MS
XI NV SES taa
E E ) Pe — tyma
ь My, as
m tyma LE NE. A y 6l
osdv Y Me yeh ZA £; mé
ddv, n°

62

FIG. 55. Stomach, Austrovenus stutchburyi. FIG. 56. Stomach, Mercenaria mercenaria. FIG. 60. Digestive
diverticulum, Austrovenus stutchburyi. FIG. 61. Digestive diverticulum, Mercenaria mercenaria. FIG. 62.
Detail of digestive diverticulum, Chione cancellata. FIG. 63. Detail of intestine just anterior to heart, Mercen-
aria mercenaria. FIG. 64. Cross section of intestine in gut loop, Mercenaria mercenaria.

JONES

172

“do

a

WAINqYIINIS зпиэлодзпу ‘YEAH ‘89 ‘Old ‘е/азерип вио!ц ‘иеэн ‘29 ‘914 ‘elyded auoiyD ‘иеэн ‘99 “DI ‘взерезие> зиоцо ‘иеэн ‘69 ‘514

19%

2
tt Dy PRA A

ZZ JA as ==

CHIONINE ANATOMY 173

sl С PNR
>> aa NN = 2 у

ae pec 3
BE
$

HR o/y ra

=a BEIN
il)
И

FIG. 69. Heart, Mercenaria тегсепапа. FIG. 70. Dorsal aspect of heart, Mercenaria mercenaria. FIG. 71.

Lateral aspect of valve between auricle and ventricle, Mercenaria mercenaria. FIG. 72. Interior of ventricle
and bulbus arteriosus, Mercenaria mercenaria.

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JONES

usd

AN NN — —
do 7 SA RN | | м
LLUIS,
LI Wa 22 > NS А» N

E Y, DAD Of li N
— GL, EYL, W
CAL, fi / y / op
LA, Y) }
Lyf

174

CHIONINE ANATOMY 175

EE
5mm
ctax
LÉ "AA AA Ea PL Oo gy 2 en
IIS
EA В Ñ Sad 2 > MN

DT

FIG. 77. Kidney, Mercenaria mercenaria. FIG. 78. Chamber between kidneys and mantle cavity, Mercenaria
mercenaria.

JONES

176

‘eryded эиощо “uajsÁs зполлаи jo BWAYIS ‘08 ‘914 'eJejpooueo эиощо "welsÄs snomau jo auayos ‘62 "II

62

08

|

177.

CHIONINE ANATOMY

11Inqy9IMmS $пиэлодзпу “wejsÁs snonmau JO эшэцос 28 ‘914 ‘е/эдерип auoiyD “wejsÁs snonmau JO эшецос “1g “Dl

c8 18

154

ASU

Jsu

deu + Addu

usu

178 JONES

npav
net
nsm
PP
eS e
nsr LA
gss
/
ns 7]
nppv
icm

83

FIG. 83. Scheme of nervous system, Mercenaria mercenaria.

вивиээлэш
elleusaseyy 'wajsÁs зполлэи [2198189 jo Pedse jeuaye] ‘56 ‘914 ‘вивигэлэш вивиаэлей/ ‘шезАз зполлэи 12198189 jo joadse ¡esiopolajuy ‘гб ‘914
‘AINGYAMS snuaaodsny “wejsÁs зполлаи 2198189 jo Padse ¡e/9]87 ‘16 ‘914 Wungyaynıs snuanoysny ‘wa\sks snoneu 12198199 jo joadse |езлоролэиу
‘06 914 ‘е/аерип euoiy) 'wajsÁs snomau [8198189 jo joadse ¡esa]e7 ‘68 914 ‘в/аерип auoıyy “uweajsÁs snoneu 12198189 jo J20dSe |PSI0POI9]UY
‘88 ‘Old eyded auomyo ‘waysks зполлэи 12198189 jo joadse ¡esaje7 ‘28 ‘914 ‘ещаеа эиощо ‘wa\sks snoneu 12199199 jo joadse [езлоролэи\ ‘98
‘DIA 'ве/ериео эиощу “wejsÁs snonau [2198189 jo joadse 1218127 “Gg ‘914 ‘ае/эзиео эиощцо “wejsÁs snoneu [2149.95 jo j0adse |езлоролэциу “pg ‘O4

179

>
=
E
<
=
<
ш
=
2.
о
EE
O

180 JONES

FIG. 94. Anterior and lateral aspects of visceral nervous system, Chione cancellata. FIG. 95. Anterior and

lateral aspects of visceral nervous system, Chione paphia.

CHIONINE ANATOMY 181

FIG. 96. Anterior and lateral aspects of visceral nervous system, Chione undatella. FIG. 97. Anterior and
lateral aspects of visceral nervous system, Austovenus stutchburyi.

182

JONES

FIG. 98. Anterior aspect of visceral nervous system, Mercenaria mercen

aria.

183

CHIONINE ANATOMY

‘вивиээлэш BLEUIDIBW ‘зао; aduun “LLL
‘Dla ‘вивиеэлэш вивиээлаи| ‘5; иемело adiy 'OLL ‘914 Anqyoyms snusronsny ‘зэюню; иемело adiy ‘601 ‘914 Anqyoyms $пиэлодзпу ‘риеб
ерэ« "801 “Ola ‘виазерип auolyd ‘риеб jeped “201 “Old "Biyded эиоцо ‘pue|6 jeped ‘901 'HI4 'eJepeoueo эиощо ‘риеб ¡epad “SO! ‘914 ‘вивиээлэш
вивиеэ1эи! ‘риеб jepad pue weysÂs зполлэи jepdad “pol ‘514 "Wungyaynıs зпиэлодзту 'wejsÁs зполлэи jepad “EOL ‘OI 'е//эзерип auoyo ‘епбиеб
lepad “ZO! “DiW ‘e//ded auoiy “wejsÁs зполлви ¡pad “LOL ‘Did ‘eJepeoues зиощо чзАоозее ‘001 ‘514 ‘верезиео auoly) ‘епбиеб jeped ‘66 ‘914

801

601

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184 JONES

SHELL

Shell structure of the species discussed
here has been studied by Barker (1964),
Oberling (1964), and Taylor et al. (1973). This
last work reveals differences among species
which may be of taxonomic value. Shells of
Chione paphia and Mercenaria mercenaria
have the same structure. The outer layer is
composite prismatic, the middle layer is
cross-lamellar becoming homogeneous in-
ward, and the inner layer is homogeneous.
Between the middle and inner layers is the
prismatic pallial myostracum, thin in M.
mercenaria. Unlike most members of the
Chioninae and Venerinae studied, C. unda-
tella lacks the outer prismatic layer. The shell
of Austrovenus stutchburyi is composed of an
outer cross-lamellar layer which becomes
homogeneous inward, a prismatic pallial
myostracum, and an inner layer which is
complex cross-lamellar to homogeneous. The
shell structure of C. cancellata as described
by Barker (1964) seems to resemble that of C.
paphia and M. mercenaria. The shells of all
venerids studied are aragonitic. According to
Barker, the outer and middle shell layers of C.
cancellata and M. mercenaria contain little
conchiolin, but the inner shell layer is rich in it.

All species are equivalve, rounded-trigonal
to ovate, robust, and fairly inflated (Figs. 1-
16). A robust shell tends to protect a clam
from smaller predators who gain access to the
soft parts by chipping away the shell (Paine,
1963). Observation of thousands of speci-
mens shows that Chione cancellata is vari-
able in elongation and inflation. Some speci-
mens, such as С. с. mazyckii Dall (1902), are
quadrate. C. undatella is so variable in outline
and sculpture that it has received many
names (Verrill, 1870; Keen, 1971). Mercen-
aria mercenaria and C. paphia are posteriorly
somewhat rostrate. More robust specimens of
C. paphia are somewhat more inflated. Of the
five species, Austrovenus stutchburyi is usu-
ally the most inflated. All are prosogyrate with
the beak subcentral to well anterior. All have a
strong external ligament seated in well-devel-
oped nymphs posterior to the beak. In very
young venerids the ligament is internal until
about the fortieth day of life, when it begins to
pass by allometric growth to the exterior
(LePennec, 1973). The ligament in juvenile C.
ulocyma Dall, a close fossil relative of C.
paphia, followed this same sequence
(LaBarbera, 1974).

All five species have radial and com-

marginal sculpture. Chione cancellata, C.
undatella and Austrovenus stutchburyi (Figs.
1, 9, 12) have cancellate sculpture consisting
of thin, erect, commarginal lamellae crossing
less-pronounced radial ribs which become
more numerous with growth by splitting and
intercalation. The commarginal ridges of A.
stutchburyi are comparatively low. In the
American species, the commarginal lamellae
form broad flanges at their posterior ends.
Such flanges are lacking in A. stutchburyi.
Strong commarginal sculpture retards bur-
rowing but promotes stability of the animal
once buried (Stanley, 1970). C. paphia (Fig.
6) has broad reflected lirae which abruptly
attenuate to flanges on the posterior slope.
This species is a very slow burrower (Stanley,
1970). C. paphia and many of its extinct rela-
tives, such as C. burnsii Dall and C. ulocyma
Dall (Palmer, 1927, 1929), have at the ante-
rior end of every other lira a scoop-shaped
process which may aid in burrowing. In C.
paphia, radial sculpture is restricted to shal-
low notches in the ventral surfaces of the
lirae. Mercenaria mercenaria (Fig. 15) has
subdued sculpture, consisting of crowded
narrow commarginal ridges at the anterior
end of the shell. On the ventral surfaces of the
ridges are faint radial incisions. Growth lines
are obvious, especially on the disc and poste-
rior Slope, and on the ventral portions of larger
animals. Fine radial ribs within the fabric of
the shell are expressed at the surface as fine
radial lines. Adult quahogs rely on their mass
to maintain their position in the substratum,
but juveniles have erect commarginal ridges
for anchorage (Pratt & Campbell, 1956).
Stanley (1970) found adult quahogs to be
rapid burrowers, but Trueman (1975) con-
siders them slow burrowers who settle into
excavations made by forcible ejection of wa-
ter from the mantle cavity. Layers in the shells
of C. cancellata and Mercenaria mercenaria
thought to be daily growth increments are
thicker in animals from warmer waters
(Barker, 1964). The sequence of thick daily
increments deposited in spring and summer
to thin increments laid down in autumn and
winter is well seen in A. stutchburyi (Coutts,
1970).

The lunule in all species is cordiform. In the
American species it is surrounded by a sharp-
ly incised line (Fig. 3). In Austrovenus
stutchburyi an abrupt change from fine radial
ribs on the lunule to much coarser ribs on the
anterior slope delimits the lunule. The
cancellate American species also have radial

CHIONINE ANATOMY 185

ribs on the lunule. The lunule of Chione
paphia is without ornament; that of Mercen-
aria mercenaria bears more or less obsolete
commarginal ridges. The lunule varies from
slightly pouting in the cancellate forms, to flat
in M. mercenaria, to slightly impressed and
sinuous in C. paphia.

All species have escutcheons. In the four
American species the left half is smooth,
strongly impressed, with a sharp dorsal mar-
gin where it joins the disc (Figs. 4, 8, 11); the
right half is somewhat rounded and crossed
by evident growth lines and the posterior ends
of the commarginal lamellae (Figs. 2, 7, 10).
The escutcheon is proportionally broader in
Chione than in Mercenaria. In Austrovenus
this feature is rather narrow, rounded, and
only slightly impressed (Figs. 13, 14). Mar-
wick (1927) noted that the escutcheon of A.
stutchburyi is less well defined than that of its
supposed American relatives, but that the
ancestor of A. stutchburyi had a fairly well-
defined escutcheon.

Chione paphia and C. cancellata are
cream-colored, with chevrons or maculae or
rays, Or some combination of these, in pale
Orange or brown. The lunule is often pig-
mented. The escutcheon bears diagonal
brown stripes, broader and fewer on the left
side. In general, specimens of C. cancellata
from the United States bear fine brown or
Orange chevrons, whereas those from the
Caribbean have maculae and rays. C.
undatella is commonly off-white without mark-
ings, although a number of colored forms ex-
ist (Verrill, 1870; Dall, 1902). Austrovenus
stutchburyi is also off-white without markings.
Mercenaria is usually pale brown or grey, but
the color morph M. m. notata (Say, 1822)
bears brown chevrons (Clench, 1928). All
species are covered by a thin yellow or tan
periostracum.

Each species has three radiating cardinal
teeth below the umbo of either valve; the for-
mula is R101010/L010101. The teeth of the
three small American species (Figs. 2, 5, 7, 8,
10, 11) are robust and not bifid, or only slightly
so. Four cardinal teeth in Austrovenus
stutchburyi and Mercenaria mercenaria are
patently bifid (Figs. 13, 14, 16). In addition to
cardinal teeth, M. mercenaria has large inter-
locking rugose areas between the posterior
cardinal teeth and the nymphs. This paired
structure probably functions as additional
teeth in preventing shear between the valves
and in securing proper occlusion. The denti-
tion of the four American species merges

ventrally into the robust dental platform before
reaching its ventral edge; in Austrovenus the
teeth extend almost undiminished in height to
the edge of the relatively small dental plat-
form. LePennec (1973) discusses the devel-
opment of larval dentition in several European
venerids. The juvenile dentition of fossil
Chione ulocyma Dali (LaBarbera, 1974) re-
sembles that of Venus striatula (=Chamelea
gallina), another member of the Chioninae,
more closely than it does that of species of
Venerupis, a member of the Tapetinae. De-
tails of the morphogenesis of dentition may
provide clues to phylogenetic relationships.

The adductor scars are large and subequal
in size (Fig. 17). The small oval scar of the
anterior pedal retractor is separate from that
of the anterior adductor, and is in a pit under
the anterior edge of the dental platform. The
triangular posterior pedal retractor scar is
confluent with the anterodorsal edge of the
posterior adductor scar. The ventral pallial
line runs nearly parallel to the ventral margin.
The pallial sinus of Chione undatella and C.
cancellata is shallow and dorsally directed
whereas those of the other species are deep-
er and anteriorly directed. The dorsal pallial
line extends from the dorsal edges of the
pedal retractor scars into the umbonal cavity,
where it is punctuated by several small dis-
crete scars.

Along the posterodorsal margin is an over-
lap device which permits this part of the mar-
gin to remain closed while the rest is open for
feeding or burrowing (Figs. 2, 5, 7, 8, 10, 11,
13, 14, 16). The edge of the left escutcheonal
margin fits into a groove in the edge of the
right valve, and is overlapped by a sinuous
extension of the right valve. This overlap de-
vice is best developed in the small American
chionines.

All species have denticles on the interior
face of the lunular, anterior, and ventral
margins, becoming obsolete or absent at the
posterior end. In the cancellate forms denti-
cles correspond to external radial ribs, and
sockets to interradial grooves. The marginal
denticles of Chione paphia and Mercenaria
mercenaria seem to correspond to radial
structures within the fabric of the shell.
Kennedy, Taylor & Hall (1969) find that a
radial rib on the underside of each radially
arranged first-order composite prism of the
outer shell layer forms a denticle at the margin.
Austrovenus stutchburyi lacks the outer layer
of composite prisms and the radial structure
which it forms in the fabric of the shell; its

186 JONES

marginal denticles are related directly to ex-
ternal sculpture. Stanley (1970) suggests that
marginal denticulation helps prevent rota-
tional shear between valves during burrowing.
As denticles do not engage when the shell is
open, as it must be during burrowing, this ex-
planation of the function of the denticles can-
not be correct. It is probable that Rudwick
(1964) is correct in supposing that zigzag
margins, such as these with denticles, reduce
the effective aperture so as to exclude pests
and sand grains.

Both Chione cancellata and Austrovenus
stutchburyi are strongly pigmented inside,
most commonly purple. C. cancellata rather
often is orange, pink, or red inside. Around
some Caribbean islands this species is white
inside with a brown or purple macula near the
posterior end; these same shells are often
less inflated than usual, and have distant
commarginal ridges and dark brown blotches
outside. C. paphia is usually pale pink or
orange inside. Mercenaria mercenaria is
most commonly purple at the posterior end,
but some specimens are entirely white inside.
C. undatella is white inside, with the teeth and
pallial sinus tinted purple.

SOFT ANATOMY

The relationships of organs are shown in
Figs. 18 and 19.

The bilobed mantle (Figs. 20, 22, 23, 25,
29) attaches to the valves along the pallial
line, and is pierced by the adductor and pedal
retractor muscles. Each lobe has inner and
outer walls, and secretes the inner shell layer,
within the pallial line (Neff, 1972b). This part
of the shell supplies calcium to neutralize
succinic acid produced by anaerobiosis when
the valves are closed; when the valves are
open and aerobiosis resumes, the inner shell
layer is restored (Crenshaw & Neff, 1969). Be-
tween the pedal retractors parallel bundles of
muscle extend from the shell mantle a few
millimeters to the pallial line and small scars in
the umbonal cavity, to suspend the mantle
and viscera (Fig. 26). Within the ventral mar-
gin bundles of muscles radiate ventrally from
the pallial line, interlace, and penetrate the
mantle folds. At the posterior end, these
muscles control the siphons. The siphonal re-
tractor muscles of Austrovenus stutchburyi
seem relatively weakly developed. There
seems to be a longitudinal band of muscle just
dorsal to the innermost mantle fold. Nerves

from the visceral and cerebral ganglia serve
the mantle. All four species examined for this
character have four mantle folds (Figs. 21, 24,
28, 30). Chione paphia probably has this
number, which seems typical of venerids
(Yonge, 1957; Ansell, 1961; Narchi, 1971). At
the anterior end of the large pedal gape, the
first and second folds fuse, as do the third and
fourth. At the posterior end of the pedal gape,
the first and second folds continue along the
edge of the shell, and the third and fourth
folds fuse to form the siphons.

Along the ventral margin the configuration of
the four folds varies among the species. In the
American species distinct vacuities, probably
blood vessels, pass longitudinally just ventral
to the line of attachment to the shell. Austro-
venus stutchburyi alone of the species ex-
amined has a possibly glandular patch of tis-
sue beneath the medial surface of the mantle
just dorsal to the fourth mantle fold. This
structure occurs in Protothaca also. Hillman &
Shuster (1966) suggest that the fourth mantle
fold is derived from the inner surface of the
third mantle fold and from the dorsally adja-
cent part of the mantle surface. Yonge (1957),
followed by Ansell (1961), suggests that the
fourth fold is the former third fold, and that the
second and third folds are the separated sur-
faces of the former second fold. If the fourth
fold was derived in the manner supposed by
Hillman & Shuster, the sensory function of the
former second fold was assumed by the rem-
nant of the former third fold; in Yonge’s model,
the functions of the former second fold were
retained by the two derivative folds. Hillman &
Shuster do not consider this aspect of the
derivation of the fourth fold. Nor is there any
guarantee that this fold originated in the same
way in all species possessing it. The inner
surface of the first mantle fold contains sev-
eral kinds of cells which secrete the various
layers of the protein-rich periostracum (Neff,
1972a) and the phenolic substrate which
when oxidized tans the periostracum (Hill-
man, 1961). Hillman (1964) found that the
fourth, innermost fold secretes mucus which
probably aids the expulsion of pseudofeces.

The siphons, the third and fourth mantle
folds fused, are complete. The conical valve
in the tip of the excurrent siphon and the inner
row of tentacles on the incurrent siphon rep-
resent the fourth fold; the ring of tentacles on
the excurrent sipon and the outer ring of
tentacles on the incurrent siphon represent
the third fold (Yonge, 1957; Ansell, 1961). All
tentacles are simple. Austrovenus stutchburyi

CHIONINE ANATOMY 187

seems to have two rows of tentacles on the
excurrent siphon. Only in this last species are
the tips of the siphons appreciably separate.
The cream color of the flesh, the white patch-
es visible through it, and the brown flecks on it
may serve to camouflage the siphons against
a light granular background. In very young
Mercenaria the siphons are relatively long
(Carriker, 1961), but in adults they are short.
The four American species have in the proxi-
mal ends of their siphons the partial flap to
which the posterior tips of the gills attach, and
valves, considered typical of venerids (Ansell,
1961). The ventral portion of the partial flap,
also known as the siphonal membrane, can
be raised to admit freely the incoming water,
or lowered to direct the water ventrally toward
the edge of the mantle cavity just anterior to
the siphons where pseudofeces accumulate,
SO as to Suspend this rejected material prior to
its expulsion from the mantle cavity via the
incurrent siphon (Kellogg, 1915). Austrovenus
stutchburyi has the partial flap, but lacks the
valves (Fig. 27). The valves in the incurrent
siphons of the American species are more or
less frilly on their free edges, and drop for-
ward from the roof and sides of the siphons.
They probably control the volume of incoming
water and aid in the expulsion of pseudo-
feces. Chione cancellata is quite capable of
ejecting forcibly sand grains deliberately in-
troduced into its incurrent siphon. The valves
in the excurrent siphon resemble human in-
ferior vocal chords, with the slot-shaped aper-
ture tending dorsoventrally. They delimit the
anal canal. They probably increase the effi-
ciency with which wastes and gametes are
expelled. Siphonal musculature of Venus
verrucosa, probably fairly closely related to
the American chionines, consists of a clearly
defined outer layer of “circular” muscles, a
main body of longitudinal muscles with irregu-
larly arrayed “circular” muscles among them,
and а very poorly defined inner layer of “circu-
lar’ muscles (Duval, 1963). The so-called
circular muscles are, as Duval explains, in
clockwise and counterclockwise helices.
The eulamellibranch gills extend from a
point between the labial palps, along the
ventral edge of the pericardium, to the dorsal
edge of the partial flap. The inner demibranch
is considerably broader than the outer, which
sends a supra-axial extension over the peri-
cardial wall (Fig. 18). Stasek (1963) has de-
termined that the anterior ends of the gills of
venerids other than the very smallest are in-
serted into the distal oral groove, to which

they are fused. There is a food groove along
the ventral edge of the inner demibranch;
whether there is such a groove at the edge of
the outer demibranch is uncertain. Kellogg
(1915) studied the movement of particles on
the gills, mantle, visceral mass, and palps of
Mercenaria mercenaria, Chione fluctifraga
and C. succincta (=C. californiensis). Foster-
Smith (1978) examined detailed relationships
between gills and palps, and movement of
particles on the palps of several species, in-
cluding some venerids. As turbidity of the
water increases, the proportion of material
which is accepted declines, and the material
rejected is moved ventrally and posteriorly on
the mantle to a collection site at the rear of the
mantle cavity near the base of the incurrent
siphon, through which it is periodically
ejected.

In cross-section, the plicae of the gills (Figs.
31-34) vary greatly from species to species.
In Mercenaria mercenaria, Chione undatella
and Austrovenus stutchburyi each plica has
one water tube, supported by rings of tissue.
In C. undatella the gill filaments are broader
on the lateral surface of the gill.

Two pairs of triangular, rather small labial
palps, dorsal and ventral, surround the mouth
(Figs. 35-39). The palps of the left side are
shown in the figures. In the three small Amer-
ican species the rugae on the palps are
coarse and few; in the other two species they
are numerous and fine. In Chione undatella a
lappet extends from the palps posteriorly be-
tween the demibranchs.

The general plan of the digestive system
and the configuration of the gut loop are simi-
lar in all five species (Figs. 40—49). This sys-
tem and the gonads are supported by numer-
ous bundles of fibers, said to be muscular
(Ansell, 1961).

In the anterodorsal edge of the foot is the
oval mouth, closely surrounded by the labial
palps. Chione undatella, C. paphia and
Austrovenus stutchburyi have small paired
globular structures adjacent to the dorsal side
of the oesophagus, between the heads of the
anterior pedal retractors (Figs. 50, 51). These
bodies apparently are not part of the nervous
system, and may be oesophageal glands
(Stenta, 1906). Some species of venerids
possess Salivary glands in the bases of the
labial palps (Berner, 1938); if any of the
species examined here have such glands, |
failed to find them. Even in so highly ad-
vanced a group of bivalves as the venerids
there are yet traces of the primitive form hav-

188 JONES

ing a head. The contention of Yonge (1953)
that loss of the head entailed loss of all asso-
ciated buccal, radular, and oesophageal
structures is not correct. The oesophagus is
lined with longitudinal epithelial rugae, closely
spaced and fine in C. cancellata, C. undatella
and Mercenaria mercenaria, but coarse in C.
paphia. In A. stutchburyi these rugae are of
various widths, and separated by thin-walled
areas seemingly devoid of tall epithelial cells.

The general structure of the stomach (Figs.
52-56) is similar among all venerids so far
examined, although there are many differ-
ences in detail (Graham, 1949; Purchon,
1960; Ansell, 1961; Dinamani, 1967; Narchi,
1971, 1972). A narrow collecting area (circu-
lar tract of Ansell, 1961) borders the proximal
end of the oesophagus, evident in Chione
undatella (Fig. 54). A shelf divides the anterior
end of the globose stomach into a dorsal hood
and a larger ventral portion. A large sorting
area extends from the upper opening into the
left digestive diverticulum, across the dorsal
surface of the shelf, around the right side of the
stomach, and onto the floor. The sorting
ridges are fine in all species but C. paphia.
The dextral extension of the stomach is
anterodorsal in Austrovenus stutchburyi (Fig.
55) and in some species of Protothaca, but
posterolateral in the American species. The
acceptance tract on the posterior wall of the
stomach is evident in Mercenaria (Fig. 56). A
somewhat rugose area, bounded anteriorly by
the major typhlosole, crosses the anterior
floor between the ventral openings into the
digestive diverticula. In Austrovenus there is a
small rugose gap in the major typhlosole be-
tween the posterior sorting area and the
opening into the right digestive diverticulum. A
thin gastric shield (Figs. 57-59) covers the
roof and most of the left interior wall of the
stomach. Kubomura (1959) has shown that
the gastric shield of Meretrix meretrix, another
venerid, is composed of an outer layer, seem-
ingly scleroprotein, probably collagen, and of
an inner layer, probably of chitin. The outer
layer contains appreciable amounts of
amylase. In addition to its supposed abrasive,
protective, and digestive functions (Owen,
1974; Kubomura, 1959), the shield with its
two prongs projecting through the upper and
lower openings into the left digestive diver-
ticulum probably helps prevent the collapse of
the stomach. The shield of Mercenaria
mercenaria (Fig. 59) has an additional rib-
strengthened process which crosses the
posterior floor of the stomach. In C. cancel-

lata and M. mercenaria a yellow spongy
mass, supposedly a digestive gland, is closely
appressed to the external roof of the stomach
(Figs. 52, 56). This tissue is in the position
said to be occupied by the pericardial gland
(Kato, 1959).

The green to brown digestive diverticula
(or midgut glands) surround the anterior end
of the stomach and communicate with that
organ through an opening near the right side
of the oesophagus, one or more openings
near the left side of the oesophagus, one
large opening at the left end of the shelf, and
in some cases by another small opening at
the left end of the shelf, posterior to the large
opening. Lobes of the major typhlosole pass
through the perioesophageal opening, and a
similar extension of the sorting area on the
shelf forms a large lobate caecum from the
large upper opening. Extending distally from
the lobes of the typhlosoles are ever-finer
tubules which lead to sacs in which digestion
occurs. The configuration, histology, and
function of these structures has been dis-
cussed by Nakazima (1956) and Owen (1955,
1966). Owen (1974) suggested that in some
bivalves digestion in the diverticula is both
intra- and extracellular. A parasitic copepod,
Pseudomyicola spinosus (Raffaele & Monti-
celli), often lives in the digestive diverticula of
Austrovenus stutchburyi (see Humes, 1968).

The midgut (posterior part of the stomach,
according to Ansell, 1961) is divided longi-
tudinally by the posterior part of the major
typhlosole and by the minor typhlosole into
the style sac on the left and the intestine on
the right. The whitish translucent crystalline
style, when present, projects well into the
lumen of the stomach. The intestine receives
wastes from the digestive diverticula and
supposedly rejected material from the sorting
areas. Owen (1966) said nothing of the func-
tions of the intestine, in conformity with the
view that the intestine serves only to mold its
contents into fecal pellets or rods. Such a
view does not explain the increased length of
the gut with increased depth, and probably
increased paucity of nutrients (Allen &
Sanders, 1966). Reid (1968) and Purchon
(1971) produced evidence that digestion oc-
curs in the midgut, increasing the efficiency of
the use of ingested material. Stewart &
Bamford (1976) found that the midgut of Mya
arenaria, in the same general group of bi-
valves as venerids based on stomach struc-
ture, does indeed absorb soluble nutrients.
They further found that digestion is cyclic and

CHIONINE ANATOMY 189

synchronous with the tidal cycle in this inter-
tidal and shallow subtidal animal, and that the
crystalline style disintegrates when the animal
is not actively feeding. Whether venerids have
such cycles is not known, but the presence of
the style in some animals, and its absence in
others preserved in the same way for the
same length of time suggests that these
clams have cyclic digestion. None of the work
done so far deals with possible digestion in
the gut loop. In all species examined here,
the gut loop is on the left side of the visceral
cavity, and the posterior end of the intestine
passes through the pericardial cavity where it
supports the heart and aortae, passes dorsal
to the posterior adductor, and ends as the
anus in the anal canal of the American spe-
cies, in the excurrent siphon of Austrovenus
stutchburyi. That digestion occurs in this post-
midgut section of the intestine is suggested by
the presence of a prominent typhlosole and a
thick epithelium, as in Mercenaria (Figs. 63,
64). The structure of the intestine (rectum) of
M. mercenaria and Chione cancellata has
been described in detail by Jegla & Green-
berg (1968a,b). These workers conclude that,
because the “important and mandatory func-
tion” of the intestine is the molding and expul-
sion of feces, the intestine in all its complexity
is nonadaptive. It is clear that more work on
this organ is needed before anyone can make
such startling and all-encompassing state-
ments.

The circulatory system is similar in all five
species (Figs. 65-70). The pericardial wall is
thin ventrally and laterally, but thickens dor-
sally and merges with the hinge mantle.
Narain (1976) suggested that firm support of
the pericardium by adjacent tissue is integral
to the maintenance of circulation. The lateral
auricles (atria) communicate with the medial
ventricle via openings fitted with valves (Fig.
71) preventing retrograde flow of the blood.
The thin-walled auricles, crossed by bundles
of possibly muscular fibers, receive blood
from the outer limbs of the kidneys via one or
more fenestrae. Numerous bundles of mus-
cles, many of which originate around the open-
ings from the auricles, cross the lumen of the
ventricle (Fig. 72). In Venus (=Chamelea)
gallina similar fibers originate a short distance
from these openings (Brunet & Jullien, 1936).
In Katelysia marmorata these fibers are
smooth (Joshi & Bal, 1976b). In the bulbus
arteriosus are longitudinal sheets which ap-
pear to be muscular. Hersh (1957) found
muscle fibers in the bulbus, but did not con-

sider the primary function of this structure
muscular. He suggested that the variety of
glandular cells indicated a secretory function.
Hersh did not find a valve between the bulbus
and anterior part of the posterior aorta. In K.
marmorata there is such a valve (Joshi & Bal,
1967b). The anterior aorta passes anteriorly
dorsal to the intestine, supplies sinuses near
the anterior end of the stomach, and con-
tinues ventrally along the anterior wall of the
visceral cavity. Nielsen (1963), Joshi & Bal
(1967b) and Brand (1972) traced a similar
vessel into the tip of the foot, and found sev-
eral derivative vessels to the stomch, intes-
tine, and gonad. A fine aorta from the vicinity
of the bulbus serves the hinge mantle. In K.
marmorata this area is served by a vessel
arising from the anterior aorta (Joshi & Bal,
1967b). The posterior aorta, having passed
into the anterior end of the bulbus, by which it
is interrupted in Mercenaria, continues pos-
teriorly ventral to the intestine. This aorta
supplies large, poorly defined sinuses on the
anterior face of the posterior adductor, and
penetrates the posterior edge of the mantle.
Duval (1963) found in short-siphoned spe-
cies, such as these, four longitudinal siphonal
haemocoels, dorsal, ventral, and lateral.
Longitudinal vacuities in the ventral edge of
the mantle are probably blood vessels. It is
assumed that the flow of blood in these spe-
cies resembles that in Anodonta anatina (L.)
(Brand, 1972).

| was unable to find with certainty the peri-
cardial glands, although tissue labelled as
digestive glands in Chione cancellata and
Mercenaria mercenaria (Figs. 40, 48) and the
pale brown anastomose tissue at the posteri-
or end of the pericardium of C. paphia (Fig.
26) may be this organ. In some other vener-
ids, this paired gland lies in the umbonal cav-
ity, near the blood sinuses of the visceral
hump (Kato, 1960), or in the mantle near the
heart (not necessarily a position different from
that cited by Kato), or on the auricles (White,
1942). White considered these glands to
empty the wastes extracted from the blood
into the pericardial cavity, but Kato found evi-
dence that they pass nitrogenous wastes to
the gills and mantle, which in turn pass them
into the water in the mantle cavity.

The pale brown kidney lies along the vent-
ral edges of the pericardium and on the ante-
rior faces of the posterior pedal retractor mus-
cles (Figs. 73-77). Kato (1959) reports that
the kidneys of Japanese venerids excrete
nitrogenous wastes and granules of melanin.

190 JONES

The thin-walled outer limbs contain greater or
lesser amounts of spongy tissue, usually most
evident at their anterior ends. The nephro-
stomes are in the anteroventral corners of the
pericardial cavity, as in Anodonta (Potts,
1967), not in the posteroventral corners, as in
British venerids (Ansell, 1961). Between the
kidney and the auricles are fenestrae, one on
either side in Chione, three in Austrovenus,
and one large and several small in Mercen-
aria. The posterior portion of the outer limb is
lined on all sides by anastomosing ridges of
spongy tissue in which are often embedded
small dark-brown calculi of fairly high refrac-
tive index. These calculi may be inexcretable
wastes stored as solids (Strohl, 1914), or per-
haps melanin granules (Kato, 1960). The
ridges of spongy tissue converge on the
posterior wall of the kidney and continue
anteroventrally as the inner limb, which emp-
ties into the suprabranchial cavity via the
nephridiopore. In Mercenaria wastes empty
into a small chamber in the midline, dorsal to
the exterior nephridiopores (Fig. 78). This
chamber is perhaps a bladder to hold wastes
when the shell is closed. The two sides of the
kidney communicate by a passage along the
floor of the organ. Connections between the
kidney and the gills were impossible to find
with the microscope used.

The nervous system (Figs. 79-83) is pale
yellow, and enveloped by a thin pellicle. There
are three pairs of ganglia, cerebral, visceral,
and pedal, their connectives, and many deriv-
ative nerves. The visceral system is the most
complex.

The cerebral ganglia (Figs. 84-93) lie just
anterior to the heads of the anterior pedal re-
tractor muscles, among a mass of tough con-
nective tissue, and are joined by a short, thick
supraoesophageal commissure. The bright
yellow caps of these ganglia in Mercenaria
(Figs. 92, 93) may be incompletely fused
pleural ganglia. Small nerves pass laterally
into the labial palps. In some animals fine
nerves are seen to pass dorsal to the adduc-
tor muscle into the anterior edge of the man-
tle. From one or both ganglia a nerve extends
posteriorly along the oesophagus to the vis-
cera. Perhaps this nerve supplies the tiny fi-
bers in the intestine observed by Jegla &
Greenberg (1968b). The main nerves from
the cerebral ganglia descend the posterior
face of the adductor muscle, and send fine
nerves into the shell mantle, and probably into
the adductor itself. Near the ventral edge of
the muscle, one branch of the nerve runs

anteriorly into the edge of the mantle, and the
other branch runs posteriorly among the
radial muscles of the mantle. This antero-
ventral pallial nerve sends numerous
branches to the mantle folds. Posteriorly it
becomes the posteroventral pallial nerve from
the visceral complex.

The cerebrovisceral connective courses
from the laterodorsal corner of the cerebral
ganglion, passes just within the lateral face of
the pedal retractor muscle and among the
colliculi of the digestive diverticulum, crosses
the gonad, runs past the ventral edges of the
gonopore and nephridiopore, leaves the
visceral mass anterior to the main body of the
posterior pedal retractor muscle, and joins the
laterodorsal corner of the visceral ganglion. In
some cases this connective sends fine nerves
to the anterior pedal retractor. The closely
fused visceral ganglia (Figs. 94-98) are af-
fixed to the anterior face of the posterior ad-
ductor by connective tissue and a thin cover-
ing membrane. A large nerve runs anteriorly
into the base of the gill, and seems to send
fibers into the plicae. The visceral ganglion
sends a fine nerve to the kidney. This nerve
has been traced in other venerids to the auri-
cle and ventricle (Carlson, 1905; Phillis,
1966). Slender nerves leave the dorsal edge
of the ganglion to serve the pedal retractor
and shell mantle. Another, larger nerve
passes posteriorly into the adductor muscle.
A short distance ventral to the ganglion the
main descending nerve sends a branch into
the posterior end of the mantle. Near the
ventral edge of the adductor the main nerve
splits: a small nerve tends posteriorly into the
excurrent siphon; a fairly large branch de-
scends among the siphonal retractor muscle
fibers and turns anteriorly in the edge of the
mantle; and the largest branch runs ventrally
along the bases of the siphons. This latter
branch sends many nerves into the siphons
and siphonal retractor muscle. At the level of
the junction of the siphons is a subsidiary
ganglion in the American species, only slightly
developed in small specimens of Chione
paphia. In all cases there seems to be a nerve
connecting the two sides of the siphonal com-
plex at the junction of the siphons. Ventrally
the siphonal complex extends almost into the
edge of the mantle, and terminates. Duval
(1963) notes that species with short siphons,
such as these and some other venerids, have
irregularly arrayed nerves in the siphons.

The cerebropedal connective runs from the
posterior face of the cerebral ganglion ventral-

CHIONINE ANATOMY 191

ly through the pedal retractor, to which in
many cases it sends fine nerves, and joins the
anterior end of the pedal ganglion. The pedal
ganglia (Figs. 99, 101-104) are extensively
fused and lie just anteroventral to the ventral
turn of the midgut, from which they are sepa-
rated by a thin screen of transverse muscles.
In Mercenaria the connective sends tiny
nerves dorsally among the splayed fibers of
the pedal retractor muscle lining the visceral
cavity. Three pairs of nerves innervate the
foot. The anterior pair extends anteriorly and
somewhat laterally to innervate the anterior
part of the foot. The middle pair passes ven-
trally and medially to the central part of the
foot. One branch of these nerves closely ap-
proaches the pedal gland. The posterior pair
runs a short distance posteriorly from the
ganglia and divides, with one branch plunging
ventrally and the other continuing posteriorly
to the posterior part of the foot. All three pairs
branch several times as they extend toward
the edge of the foot. Ansell (1961) records
only two pairs of pedal nerves, the anterior
and middle. In Katelysia marmorata, an an-
terior pair of pedal nerves innervates the
sides of the foot, and a posterior pair sends
branches into the anterior and posteror ends
of the foot (Joshi & Bal, 1967a). Nielsen
(1963) states that the posterior nerves from
the pedal ganglia innervate the intestine; | did
not find such a relationship. Structures be-
lieved to be statocysts (Fig. 100) are visible in
some animals in the anterior edge of the foot
at the ends of tiny nerves extending from the
pedal ganglia approximately parallel to the
anterior pedal nerve. The statocyst nerve is
said to arise from the cerebral ganglion
(Pelseneer, 1906). Some of these structures
contained a tiny yellow stone, presumably the
statolith. | did not find statocysts near the
pedal ganglia; Nielsen also failed to find them
in this position.

The pedal gland (Figs. 104—108) is situated
in the midline of the foot among the crossed
fibers of the pedal retractors. In juveniles this
organ is byssiferous (Belding, 1912; Carriker,
1961; D’Asaro, 1967). Barrois (1885) stated
that among venerids, only tapetinids retain
this byssiferous gland in the adult. Boutan
(1895) noted that Venus (=Pitar) rudis loses
the byssal gland during ontogeny. Nielsen
(1963) found a pedal gland in adult Katelysia,
in which the function is unknown. Adult
Venerupis pullastra, a nestler, retains a func-
tional byssal gland (Mahéo, 1969). This gland
is byssiferous in the adults of the small

venerid clam, Transennella (Narchi, 1970).
Ladd (1951) collected Chione grus (Holmes)
apparently attached to sea grass. The collec-
tions of the Museum of Comparative Zodlogy
contain hundrds of adult specimens of this
small chionine taken from buoys; almost cer-
tainly these animals were byssally attached. |
have found the structure in Protothaca as
well. The pedal gland is white, rather globular,
and mammilate on its inner surface. A narrow,
pellicle-covered duct leads anteroventrally to
a slot in the edge of the foot. In all five species
the gland is rather small, and not anchored by
the broad band of muscle to be expected if
this organ were byssiferous. In the adults of
larger species this gland may secrete mucus
to lubricate the tip of the foot during burrow-
ing. In adult Gemma gemma this organ se-
cretes a mucilaginous substance which aids
in crawling (Sellmer, 1967). Trueman (1975)
noted that a foot coated with mucus-glued sand
grains has a superior grip on the substratum
during burrowing. Yonge (1962) regarded the
presence of the byssal apparatus in some bur-
rowing adults as the probable retention of a
structure advantageous to juveniles, and
therefore neotenous or paedomorphic.

Follicles of the ripe gonad (Figs. 109, 110)
occupy all the space in the visceral cavity
around the digestive system (Fig. 19). Tribu-
tary ducts from the follicles gradually converge
posterodorsally to form the gonoduct, which
passes beneath the pericardium to empty via
a discrete gonopore into the suprabranchial
cavity. Most animals examined were ripe
females with stalked and free ova filling the
follicles and ducts. The ova are about 0.3 mm
in diameter. The gonads of an adult specimen
of Mercenaria of undetermined sex (Fig. 111)
consists of tough yellow tissue through which
are scattered seemingly unconnected clus-
ters of pale yellow follicles. Moore & López
(1969) found that Chione cancellata is sexu-
ally mature by the time it is about 15 mm long,
and the animals are then clearly male or fe-
male. The sex ratio is probably 1:1. Young M.
mercenaria are bisexual with strong male
predominance (Loosanoff, 1936). At the age
of about 10 months, the animals become de-
finitive males or females, and become func-
tional about a year later. A few adults are
functional hermaphrodites, but change of sex
does not seem to occur in adults. Both M.
mercenaria and C. cancellata have 19 pairs
of chromosomes (Menzel, 1968). Sexual de-
velopment of the other species has not been
studied.

192 JONES

DISCUSSION

The differences in both shell and soft parts
among the five species are summarized in
Table 1; in Table 2 the number of differences
between any two species are summed. These
differences and others not easily represented
in this form are discussed in turn.

Taylor (1973) suggested that the primitive
structure of the shells of most heterodonts,
including lucines and venerids, consists of an
outer layer of composite prisms, a middle
cross-lamellar layer, the pallial myostracum,
and an inner layer of complex cross-lamellae.
He supposes that in the course of evolution
the outer prismatic layer is lost, and that the
other layers becomes progressively homo-

TABLE 1. Anatomical differences among Chione
cancellata, Chione undatella, Chione paphia, Mer-
cenaria mercenaria, and Austrovenus stutchburyi.

C.c. C.u. C.p. Mm. As.

Posterior flanges + + >

No posterior flanges + +
Lunule sharply defined + + + +
Lunule poorly defined +
Escutcheon well defined + - u +
Escutcheon poorly defined +
Cardinal teeth simple + + +

Cardinal teeth bifid u +

Teeth merge with platform + + 7 +
Teeth extend to edge of

platform +
Pallial sinus shallow,

ascending + +
Pallial sinus деерег,

anterior + + +
Tips of siphons fused + > - +
Tips of siphons separate -
Valves in siphons + - + +
No valves in siphons +
Subsidiary ganglia + + +
No subsidiary ganglia +
Palp rugae coarse + + +
Palp rugae fine + +
Oesophageal rugae close + + + +
Oesophageal rugae distant +
Stomach sac posterolateral + + + +
Stomach sac anterodorsal +
1 fenestra/auricle + - +
More than 1 fenestra/

auricle + +

TABLE 2. Зит$ of anatomical differences between
any two species.

Species C.c: C.u. Cp. Mm. As.
Chione cancellata 0
Chione undatella 0 0
Chione paphia 1 1 0
Мегсепапа тегсепапа 5 5 4 0
Austrovenus stutchburyi ey nee 8 0

geneous. Не suggested that homogeneous
layers of tiny crystals are inexpensive to form.
The repeated solution and redeposition of the
inner layer in intertidal and shallow subtidal
clams (Crenshaw & Neff, 1969) would prob-
ably require such economy of effort. If
Taylors evolutionary sequence be correct,
then Austrovenus stutchburyi is more ad-
vanced than the eastern American chionines
in lacking the outer layer of composite prisms,
but less advanced in retaining some complex
cross-lamellae in the inner layer. In this
scheme, Chione undatella is the most ad-
vanced. Taylor & Layman (1972) showed that
composite prisms are particularly resistant to
pinpoint stress. This array of material forms
the sculpture of the three eastern American
species. If the function of commarginal sculp-
ture is resistance against disinterment, then it
is advantageous for this sculpture to be
formed of material resistant to the pinpoint
stress of impinging sand grains. Taylor noted
(1973) that the very earliest lucines, much
older than the oldest venerids, had the outer
composite-prismatic layer, and assumes that
this structure is primitive in venerids as well. It
may be, however, that this layer evolved
separately in venerids, and is relatively new,
rather than primitive. It seems to be true that
this layer can be secondarily lost. If, as
Stanley (1970) maintained, sculpture is ad-
vantageous to the possessor, and if, as Taylor
suggested, the outer layer (which forms the
sculpture) is primitive, then one would expect
the early venerids to have been sculptured,
and that the sculptured condition and the shell
layer which gives rise to it to have been re-
tained by most later generations of venerids.
Examination of the vast literature shows that
fossil venerids were generally devoid of
sculpture from their beginning in the mid-
Mesozoic until some time in the Eocene,
when pitarines, a western Tethyan group,
developed commarginal or even zigzag sculp-
ture. Mercenaria, and through Mercenaria,
Chione are almost certainly descended from
Middle Eocene Rhabdopitaria of the Ameri-
can Gulf Coast (Stenzel, 1955). Mercenaria
has had this outer layer since its first appear-
ance in the Middle Oligocene. Chione unda-
tella, a descendent of Mercenaria, seems to
have lost this layer. Taylor, Kennedy & Hall
(1973) noted that some species of venerids
are variable in their possession of the outer
layer, but do not mention whether C. unda-
tella is one of these species. That the sculp-
ture-bearing Venerinae are probably very

CHIONINE ANATOMY 193

closely related to the Chioninae is suggested
by shell structure, internal anatomy, and pos-
sible fossil intermediates of Late Oligocene
and Early Miocene age (see also Fischer-

Piette, 1975).
It is possible that the absence of the com-
posite prismatic layer in Austrovenus

stutchburyi is primitive. The projecting poste-
rior tips of this species are often so worn as to
expose the pigmented inner layer. The Amer-
ican species are almost never abraded in this
way. Although Taylor & Lyman (1972) as-
serted that both cross-lamellae and compo-
site prisms resist erosion, in these cases
composite prisms are superior to cross-
lamellae.

Radial sculpture may have arisen directly in
some instances by exaggeration of the radial
composite prisms, which also form ventrally
the marginal denticles. Rhabdopitaria has
both the composite prismatic layer and the
denticles, but not the radial sculpture
(Stenzel, Krause & Twining, 1957). Middle
Oligocene Mercenaria mississippiensis has
the commarginal sculpture typical of young
Recent Mercenaria, fairly well developed
marginal denticles, but only hints of radial
sculpture. In forms intermediate between
Mercenaria and Chione, seemingly coeval
with M. mississippiensis, and in Late Oligo-
cene species of Chione, radial sculpture con-
sists of riblets which are mere extensions of
the marginal denticles onto the ventral sur-
faces of the commarginal ridges. These rib-
lets probably acted as brackets or supports
for the somewhat thin commarginal lamellae
in their function as anchors against disinter-
ment. By the Middle Miocene these radial ele-
ments became continuous across the inter-
lamellar space, as in Chione chipolana Dall.
(For this and other fossil American chionines,
see Dall, 1903, and Palmer, 1927, 1929.)
Recent Chione pubera (Valenciennes) and C.
intapurpurea (Conrad) retain the older mode
of radial sculpture. The radial ribs of Austro-
venus stutchburyi seem to involve most of the
thickness of the shell, and probably arose in a
manner different from that suggested for
Chione and Mercenaria. Chione undatella
has radial sculpture, despite the absence, or
loss, of the outer shell layer; presumably the
next layer has been pressed into service.

It seems likely that sculpture can be formed
from a variety of crystalline arrays, usually
from the outermost prismatic layer among the
Chioninae and Venerinae, and is sufficiently
adaptive to have arisen independently in

separate lineages. It also seems clear that
Austrovenus stutchburyi represents a stage
in the structural evolution of the shell different
from that exemplified by the American
chionines.

Posterior flanges are evident in many
American chionines, fossil and living, and in
some venerids of the Miocene deposits of the
Vienna Basin and Pliocene deposits of Italy,
but are absent in Austrovenus stutchburyi.
These flanges are adjacent to that part of the
margin near which the siphons protrude, and
may protect the siphons from abrasion and
bites. Carter (1967) suggests that spines in
this position on Hysteroconcha, a pitarine, and
on Hecuba, a donacid, discourage predators.

Austrovenus stutchburyi alone of the five
species lacks a well-defined lunule. Every
American chionid, of whatever epoch, has a
well-defined lunule surrounded by an incised
line. In this respect, Austrovenus more closely
resembles species in the Tapetinae, Meretric-
inae, and Circinae. The function of a well-
defined lunule is unknown. Ansell (1961) sug-
gests that a flat lunule, like that of Mercenaria,
may aid in burrowing. Cox (1969) noted that
the lunule on the outside of the shell corre-
sponds to the track of the growing antero-
dorsal hinge structures on the inside, and is
composed of the same shell layer as the
dentition. The way in which this relationship
might affect the degree of definition of the
lunule is unclear.

All American chionines have well-defined
impressed escutcheons, usually relatively
broad in the smaller species. Austrovenus
resembles such tapetines as Venerupis and
Katelysia in its weakly defined escutcheon.
The overlap device of living American
chionines is well developed; in some extinct
species this structure seems rather weak. Ina
general way, those species with poorly devel-
oped overlap devices were short-lived, or
restricted in range, or both; those species with
this structure well developed were longer-
lived, or more widespread, or both. Toward
the end of the Miocene, polydorid polychaetes
invaded the shells of many species of Chione.
In this same span of time, many species be-
came extinct. It is tempting to see a causal
relationship between these trends. Most of
the specimens of A. stutchburyi from Auck-
land Harbour were infested with polydorids.
This clam also has a rather weak overlap
device, and lives with the posterior end of the
shell projecting from the substratum, an open
invitation to the polydorid pests. Austrovenus

194 JONES

stutchburyi existed in the Pliocene (Powell,
1934), when its escutcheon was better de-
fined (Marwick, 1927). The overlap device is
weak to absent in many species of Proto-
thaca, in most tapetines (see Fischer-Piette &
Métivier, 1971), and in most venerids before
the Oligocene.

Bifidity of teeth may represent an increase
in the number of effective teeth from a few
basic elements. Additional dental processes
may distribute shearing stress more evenly
and so prevent fracture, especially in species
with relatively slight teeth, such as Austro-
venus stutchburyi, and in species with rela-
tively massive shells, such as Mercenaria
mercenaria. Lateral teeth or tooth-like struc-
tures would serve the same end. All eastern
American species of Chione, living and ex-
tinct, are of small or medium size, and have
simple teeth. Occasional specimens of C.
pubera (Valenciennes), the largest living
Atlantic species of this genus, have an extra
tooth in the right valve anterior to the cardinal
teeth. All species of Mercenaria are, as
adults, of medium to large size and massive;
they and Rhabdopitaria and a few other,
small, Middle Eocene pitarines of the Gulf
Coastal Plain have a rugose area adjacent to
the nymphs and some cardinal teeth bifid. On
the Pacific coast, where until recently
Mercenaria has been absent, many species
of Chione, especially those of the subgenus
Chionopsis, are as large as the quahog and
have bifid cardinal teeth. Any relationship be-
tween angle of rotation during burrowing
(Stanley, 1970) and number of dental promi-
nences is hard to discern. The sample is
small, however, and further research might
reveal some such relationship.

The extension of the teeth almost undimin-
ished to, and even beyond, the edge of the
dental platform is unknown in American spe-
cies of Chione, although it occurs commonly
in Protothaca (Keen, 1971) and in some
tapetines (Fischer-Piette & Métivier, 1971). п
Chione and Mercenaria the teeth merge
gradually ventrally into the edge of the rather
robust dental platform. In this character,
Austrovenus resembles Protothaca.

Stanley (1970) provides information on 18
species as to size and direction of the pallial
sinus, and as to depth and attitude in the sedi-
ment. Those species with shallow pallial
sinuses, and presumably short siphons, all
live with their posterior tips within 2 cm of the
surface of the substratum, or even projecting
from it. Those species with deep sinuses live

more than 1 or 2 cm below the surface, many
within more or less permanent burrows. There
seems not to be any correlation between at-
titude in the substratum and direction of the
sinus.

In addition to the partial flap at the proximal
ends of the siphons, many venerids, including
the four American species discussed here,
have paired membranes in the excurrent
siphon and a curtain-like valve in the incurrent
siphon. These structures presumably aid the
closer regulation of the flow of water into and
out of the mantle cavity. Gemma gemma
(Totten) (Sellmer, 1967) and some species of
Protothaca have only the valve in the excur-
rent siphon. Austrovenus entirely lacks valves
in the siphons. The four American species
have subsidiary ganglia at the bases of their
siphons, probably for finer, more integrated
control of the siphons. Austrovenus lacks
subsidiary ganglia. Perhaps the separation of
the tips of siphons in Austrovenus increases
control of excurrent flow. Ansell (1961) con-
siders separation of the tips of the siphons as
a specialization for life in very turbid, shallow
waters. Some of the American species live in
waters seemingly as shallow and turbid as
those inhabited by Austrovenus, yet have fully
joined siphons. It seems likely that once a
lineage of clams had evolved structures so
adaptive as internal siphonal valves, it would
not then lose them; Austrovenus and its
ancestors probably never had these valves.

Coarseness and number of rugae on the
labial palps, and size of the palps relative to
the area of the gills seem related to turbidity of
the environment. According to Ansell (1961),
animals in turbid waters have relatively large
palps with many and large rugae capable of
considerable muscular activity and of creating
complex ciliary currents. Ansell found that
species of Venerupis living in turbid water
have large palps with many small ridges, and
venerids of the sublittoral zone have simple
palps. The arcid Anadara anomala Reeve
lives in sand and has relatively small palps
with some 43 thick, broad rugae, whereas
Anadara cuneata (Reeve) inhabits mud and
has relatively large palps with some 150 long,
slender rugae (Lim, 1966). Chione cancellata
and C. undatella live in shallow, turbid water,
but have the small palps with few rugae ex-
pected of species in deeper, less turbid water.
The palps of Mercenaria mercenaria and
Austrovenus stutchburyi, although rather
small, have the many ridges postulated for
dwellers in turbid water. C. paphia lives in

CHIONINE ANATOMY 195

deeper, clearer water, and, as predicted, has
small palps with few large ridges. Work on
ciliary currents on the palps of these species
might show closer adaptation to turbidity than
the size of palps and number of ridges might
suggest.

The significance of the size and spacing of
the longitudinal ridges in the oesophagus is
unknown. Perhaps they are related to the
quantity and size of particles accepted.

All species examined have type-V stom-
achs (Purchon, 1960). There is a difference in
shape, however. In the four American species
the dextral extension of the stomach is lateral
and slightly posterior to its junction with the
main part of the stomach, but in Austrovenus,
as in Protothaca, this extension is somewhat
anterodorsal to the rest of the stomach.
Among venerids there are variations of shape
and detail within the type-V stomach which
may be useful in determining relationships at
levels lower than the superfamilial and famil-
ial, and in exploring adjustments between
stomach structure and the kinds and sizes of
materials accepted. Gut contents of all five
species consisted of grey mud and algal cells.
The ridges of the sorting areas in Chione
paphia, like the rugae on the palps and in the
oesophagus, are coarse, perhaps to deal with
a relatively broad array of particle sizes in the
clearer, deeper waters.

The significance of the number of fenestrae
between the outer limb of the kidney and the
auricle is not known. Each of the three spe-
cies of Chione has one such opening; Mer-
cenaria has one large fenestra in the same
position as that in Chione and several much
smaller ones anterior to it. Austrovenus
stutchburyi and Neotrigonia margaritacea,
both about the size of the small chionines,
have three and two fenestrae, respectively.
The number of fenestrae is not dependent
solely on size.

CONCLUSIONS

It is evident from Table 2 that the three spe-
cies of Chione are very similar to one another
in both soft and hard parts. Because it has
robust commarginal ridges, C. paphia is as-
signed by all workers to a subgenus different
than the nominate subgenus, to which C.
cancellata, the type, and C. undatella belong.
The fossil evidence is ambiguous, but sug-
gests that C. paphia is more closely related to
species of the subgenus Panchione Olsson

(1964) than to those of Lirophora Conrad.
Chione undatella seems to lack the structures
identified as oesophageal glands in the other
three small species, and is alone in having a
lappet extending from the labial palps to the
gills. Oligocene and Miocene fossils, as well
as anatomy, show that the three small Ameri-
can species are closely related.

Mercenaria mercenaria differs from the
small American chionines in fewer than half of
the characters considered, even though their
lineages diverged before the Late Oligocene.
Two of these differences, the dentition and
the number of openings between the kidney
and the auricle, are probably functions of the
greater adult size of Mercenaria, which lives
well below the surface of the substratum with
only the tips of its siphons protruding from the
substratum. Chione, with its shallow sinus
and well-developed flanges, lives with the
posterior tip of the shell projecting from the
sediment. Differences in the size of rugae on
the labial palps seem related to differences in
size and volume of particles ingested. In
complex characters, such as the shape of the
escutcheon, degree of definition of the lunule,
configuration of the stomach, possession of
valves in the siphons, and in other, perhaps
simple characters, such as complete fusion of
the siphons and possession of subsidiary
siphonal ganglia, Mercenaria resembles
Chione. The resemblance of Chione, especi-
ally the Oligocene species from the Gulf
Coastal Plain, and juvenile Mercenaria with
its commarginal lamellae and similar shell
structure suggests that Chione arose from
Mercenaria by neoteny. Soft anatomy ap-
pears to be conservative.

Austrovenus stutchburyi differs from like-
sized Chione in almost all 13 characters, sim-
ple and complex. In some characters it re-
sembles Mercenaria, but in many concho-
logical characters it resembles equally well
Protothaca and some members of the
Tapetinae. The differences of anatomy, par-
ticularly the stomach, dentition, and siphons,
and the lack of fossil intermediates indicate
that Austrovenus does not belong to the
genus Chione, and may not belong to the
Chioninae. It seems more likely that the simi-
larity of Austrovenus to Chione in sculpture is
the result of convergent evolution of very dif-
ferent lineages adapting to a shallow infaunal
mode of life in shifting substrata in the inter-
tidal and shallow subtidal zones.

Finally, this work suggests that soft anat-
omy, details of the structure and configuration

196 JONES

of the shell, and the fossi! record together can
provide enough information for the detection
of phylogenetic relationships, and for the con-
struction of a taxonomic scheme reflecting
those relationships.

ACKNOWLEDGEMENTS

| am pleased to acknowledge the assist-
ance of many people in the furthering of this
research. Dr. Elaine Hoagland, Dr. Daniel
Fisher, Stanley Riggs, Sheri M. Skinner, Dr.
Philippa Black, Dr. Licia Penna, Dr. Kenneth
Boss, and Dr. Judith P. Grassle helped collect
or provided specimens. Dr. Arthur Humes
identified the copepod. Dr. Howard Sanders
and the Woods Hole Oceanographic Institu-
tion provided space and equipment. Dr.
Thomas Waller critically read the manuscript.
Mrs. Thomas Haggerty, LeMoyne Mueller,
Margaret Dimmock and Jane M. Peterson
helped prepare the manuscript. The R. A.
Daly Fund of the Department of Geological
Sciences at Harvard University, and the So-
ciety of the Sigma Xi supported my field work.
To Dr. Ruth D. Turner | give especial thanks
for her help and encouragement.

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198 JONES

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CHIONINE ANATOMY 199

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>
Vol. 19, No. 1 MALACOLOGIA 1979 —
CONTENTS
J. F. QUINN, Jr.
Biological results of the University of Miami Deep-sea Expedi-
tions. 130. The systematics and zoogeography of the gastropod
family Trochidae collected in the Straits of Florida and its
approaches ... .: 2. 1-2... а.о. pin nie’ CORP SNS
М. MARTOJA et С. THIRIOT-QUIEVREUX
Appareil génital de Carinaria lamarcki (Gastropoda Heteropoda); ae
structure et affinités ..:.... 28208 MR CR decors ie ООО ОЗ
М. J. $. TEVESZ and J. С. CARTER
Form and function in Trisidos (Bivalvia) and a comparison with
other burrowing arcoids ....: -.: cn 2m A ae o 7
B. PINEL-ALLOUL et E. MAGNIN A
Cycle de développement, croissance et fécondité de cinq popula- ly
tions de Lymnaea catascopium catascopium (Gastropoda, x
Lymnaeidae) au Lac Saint-Louis, Québec, Canada ..................... es BERN
K. KERTH | . S
Phylogenetische Aspekte der Radulamorphogenese von Gas- |
"ОРОЧеп...........:..-. eee etter eaten seen не nee ER
С. В. РСКЕМ BR:
AUN
Non-pelagic reproduction of some Antarctic prosobranch gastro- R AR:
pods from Signy Island, South Orkney Islands ............................ 109
C. S. LIPTON and J. MURRAY Bu
Courtship of land snails of the genus Partula ..................... ee = 12955
P. H. RUDOLPH ‘4
‚ An analysis of copulation in Bulinus (Physopsis) globosus (Gas- AN à
tropoda: Planorbidao) -........:..... дла RSS и. #4
С. С. JONES | Y
Anatomy of Chione cancellata and some other chionines (Bi- | в:
мама; Мепепдае) 2 га ев SAR RS ONE 1807
an
¿A
A
ni
Tay
у
54
г.
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i

SS A O их

MALACOLOGIA

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W. D. RUSSELL-HUNTER
ELMER G. BERRY, Emeritus Syracuse University, New York

Germantown, Maryland
NORMAN F. SOHL

KENNETH J. BOSS United States Geological Survey
Museum of Comparative Zodlogy Washington, D.C.
Cambridge, Massachusetts
RUTH D. TURNER, Alternate
JOHN B. BURCH Museum of Comparative Zodlogy
Cambridge, Massachusetts
MELBOURNE R. CARRIKER
University of Delaware, Lewes SHI-KUEI WU, Vice-President

University of Colorado Museum, Boulder
GEORGE M. DAVIS, Executive

Secretary-Treasurer

Institute meetings are held the first Friday in December each year at a convenient place. For | ;
information, address the President. |

Copyright, © Institute of Malacology, 1980

1980

EDITORIAL BOARD

J. A. ALLEN
Marine Biological Station,
Millport, United Kingdom

E. E. BINDER

Muséum d'Histoire Naturelle
Geneve, Switzerland

A. H. CLARKE, Jr.
National Museum of Natural History
Washington, D.C., U.S.A.

E. S. DEMIAN
Ain Shams University
Cairo, A. R. Egypt

C. J. DUNCAN
University of Liverpool
United Kingdom

Z. A. FILATOVA
Institute of Oceanology
Moscow, U.S.S.R.

E. FISCHER-PIETTE
Muséum National d'Histoire Naturelle
Paris, France

V. FRETTER
University of Reading
United Kingdom

E. GITTENBERGER
Rijksmuseum van Natuurlijke Historie
Leiden, Netherlands

A. N. GOLIKOV
Zoological Institute
Leningrad, U.S.S.R.

A. V. GROSSU
Universitatea Bucuresti
Romania

T. HABE
National Science Museum
Tokyo, Japan

A. D. HARRISON
University of Waterloo
Ontario, Canada

K. HATAI
Tohoku University
Sendai, Japan

B. HUBENDICK
Naturhistoriska Museet
Göteborg, Sweden

A. M. KEEN
Stanford University
California, U.S.A.

R. N. KILBURN
Natal Museum
Pietermaritzburg, South Africa.

M. A. KLAPPENBACH
Museo Nacional de Historia Natural
Montevideo, Uruguay

J. KNUDSEN
Zoologisk Institut & Museum
Kobenhavn, Denmark

A. J. KOHN
University of Washington
Seattle, U.S.A.

Y. KONDO
Bernice P. Bishop Museum
Honolulu, Hawaii, U.S.A.

С. М EAL
McGill University
Montreal, Canada

J. LEVER
Amsterdam, Netherlands

A. LUCAS
Faculté des Sciences
Brest, France

N. MACAROVICI
Universitatea “Al. I. Cuza”
lasi, Romania

C. MEIER-BROOK

Tropenmedizinisches Institut
Túbingen, Germany (Federal Republic)

H. K. MIENIS
Hebrew University of Jerusalem
Israel

J. E. MORTON
The University
Auckland, New Zealand

R. NATARAJAN
Marine Biological Station
Porto Novo, India

J. OKLAND
University of Oslo
Norway

T. OKUTANI
National Science Museum
Tokyo, Japan

W. L. PARAENSE
Universidade de Brasilia
Brazil

J. J. PARODIZ
Carnegie Museum
Pittsburgh, U.S.A.

C. M. PATTERSON
University of Michigan
Ann Arbor, U.S.A.

W. F. PONDER
Australian Museum
Sydney

A. W. B. POWELL
Auckland Institute & Museum
New Zealand

R. D. PURCHON
Chelsea College of Science & Technology
London, United Kingdom

О. RAVERA
Euratom
Ispra, Italy

М. W. ВУМНАМ
University College of North Wales
Bangor, United Kingdom

S. G. SEGERSTRALE
Institute of Marine Research
Helsinki, Finland

G. A. SOLEM
Field Museum of Natural History
Chicago, U.S.A.

F. STARMÜHLNER
Zoologisches Institut der Universitat
Wien, Austria

У. |. STAROBOGATOV
Zoological Institute
Leningrad, U.S.S.R.

W. STREIFF
Université de Caen
France

J. STUARDO
Universidad de Chile,
Valparaiso

T. E. THOMPSON
University of Bristol
United Kingdom

FETO O PERO
Societa Malacologica ltaliana
Milano

W. S. S. VAN BENTHEM JUTTING
Domburg, Netherlands

J. A. VAN EEDEN
Potchefstroom University
South Africa

J.-J. VAN MOL
Université Libre de Bruxelles
Belgium

N.H. VERDONK
Rijksuniversiteit
Utrecht, Netherlands

B. R. WILSON
National Museum of Victoria
Melbourne, Australia

С. М. YONGE
Edinburgh, United Kingdom

H. ZEISSLER
Leipzig, Germany (Democratic Republic)

A. ZILCH

Natur-Museum und Forschungs-Institut
Senckenberg

Frankfurt-am-Main, Germany (Federal
Republic)

MALACOLOGIA, 1980, 19(2): 201-207

MULTIVARIATE ANALYSIS OF DESERT SNAIL DISTRIBUTION
IN AN ARIZONA CANYON

Robert T. Dillon, Jr.

Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, U.S.A.
and
Department of Malacology, The Academy of Natural Sciences of Philadelphia

ABSTRACT

Multiple discriminant analysis and principal component analysis were found quite useful in
interpreting distributions of two land snails in a desert canyon in Arizona. Snail presence and
abundance in small, arbitrarily chosen sites can be accurately predicted from five environmental
variables: elevation, slope angle, slope aspect, percent vegetational cover, and substrate type.
Though correlation among the environmental variables was high, vegetational cover was found
to account for most of the variance in snail presence. Independent of vegetation, slope aspect,
slope angle, and elevation were not demonstrated to affect the presence of snails. The two snail
species commonly found living in the canyon, Discus cronkhitei and Sonorella baboquivariensis
cossi, differ significantly in their preference of slope angle and substrate. It is suggested that
Sonorella was found more commonly on steep rocky slopes because it requires rocks for shelter.
Discus, a much smaller snail, can find adequate shelter in loosely packed humus and thus

inhabits shallower slopes where humus accumulates.

INTRODUCTION

Boycott (1934) suggested that the major
factors influencing habitat selection by land
snails are shelter (protection from desiccation
and predation) and availability of lime. More
recent work has emphasized a third important
consideration, food availability. There is evi-
dence of correlation between snail abun-
dance and both the amount of calcium and
organic matter in soil samples (Burch, 1955).
In the western U.S.A., many land snails are
more often found associated with certain de-
ciduous trees than with pines or grasses, im-
plying that the litter from deciduous trees
serves as food (Karlin, 1961). Grime & Blythe
(1969) found two species of snails inhabiting
opposite slopes of the same pass and feeding
on different plants, but they suggested that
climatic rather than vegetational differences
were responsible for the separation. Differ-
ences in the sites of activity of several land
snails have been interpreted as adaptations
facilitating coexistence (Cameron, 1978).

Perhaps the major difficulty in all of these
studies has been that of dealing with environ-
mental variables often unmeasured or corre-
lated with each other. Cover, moisture, food,
lime, Competition and predation are surely
only a few of the factors potentially influencing
the local distribution of land snail populations.

In this investigation | examine the abundance
of individuals of two snail species in quadrat
samples from a canyon in southern Arizona.
Since rainfall is quite low in the area, meas-
ures reflecting cover, moisture, and tempera-
ture should account for a large part of the
variance in snail distribution observed. The
importance of unmeasured factors such as
lime were not addressed by this study.

How accurately can snail presence at a
small site in the desert be predicted from alti-
tude, slope angle, slope aspect, percent
vegetational cover and substrate? Which of
these variables is most important in explain-
ing the variance? Do the two species differ in
their local distributions, and if so, which vari-
ables seem best correlated to these differ-
ences? | have employed multivariate analysis
to address these questions. If multivariate
Statistical techniques can be demonstrated
useful in the relatively simple desert environ-
ment, their application to more complex sets
of distributions or to environments where im-
portant variables are more difficult to identify
will seem promising.

METHODS

Arch Canyon is located in Organ Pipe
Cactus National Monument, Arizona, about

(201)

202 DILLON

TABLE 1. Environmental variables measured at each site.

Standard

Variable Mean deviation Maximum Minimum
Altitude
(feet (meters)) 3160 (963) 230(70) 3700 (1128) 2700 (883)
Slope aspect
(degrees) 73 180 0
Slope angle
(degrees) 21 50 0
Substrate type
(coded) 4.4 6 1
Vegetational
cover (%) 56 100 0

21 кт Нот the Mexican border (32°02’ М,
112°42’ W). Its mouth at 2560 ft (780 т) alti-
tude is well within the limits of the Sonoran
Desert, and cacti comprise a large portion of
the vegetation, but at the top of the canyon
(4000 ft., 1219 m) shrubs and trees dominate.
On 5 to 10 January, 1978, quadrat samples
4m? each were made at 129 arbitrarily
chosen sites in the canyon. Smaller sample
areas might have permitted better estimation
of the actual environment experienced by the
snails, but a sample size of at least 4 m? was
dictated by the scarcity of individuals.

Measurements of five environmental vari-
ables were made at each site (Table 1). Alti-
tude was estimated to the nearest 50 ft
(15.2 m) from a topographic map. Slope as-
pect was determined to the nearest 45° on a
scale from 0° to 180°, evaluating both east
and west at 90°. | measured slope angle with
an inclinometer set on a meter stick lying flush
with the ground and oriented upslope. Sub-
strate type was scored on a scale from 1 to 6,
with 1 designating solid rock; 2, coarse cobble
(diameter more than 25 ст); 3, fine cobble
(diameter less than 25 cm); 4, sand; 5, dirt;
and 6, humus. Vegetational cover was esti-
mated to the nearest 25%. Notice that the dis-
tributions of these variables at best only ap-
proximate normality, for each variable is
broken into a small number of discrete values.
The results of my analyses are therefore only
approximations.

Each quadrat was thoroughly searched for
snails by turning rocks and sorting through
humus. The two snail species commonly
found living were the helminthoglyptid
Sonorella baboquivariensis cossi Miller and
the endodontontid Discus cronkhitei (New-
comb). Sonorella was occasionally observed

in the morning actively foraging on the sur-
face, but Discus was only seen lying dormant
in sheltered areas. Forty individuals of
Sonorella were found in 21 quadrats, while 59
Discus inhabited 32 quadrats. Rocks were
replaced and all snails returned to the quad-
rats after sampling.

The multivariate analytical methods | used
will be briefly described by example. Each of
my 129 sample sites can be imagined as a
point plotted in five dimensional space, where
the axes are measures of the five environ-
mental variables. Using factor analysis, new
axes (factors) running through this five di-
mensional space can be described. In princi-
pal component analysis, a type of factor
analysis, the axes are generally uncorrelated
with one another and chosen to maximize the
variance explained. Thus if correlation among
the original variables is high, the data can be
expressed in much fewer than 5 axes with
little loss of information. In discriminant func-
tion analysis, the axes chosen are those that
maximize the separation of two or more
groups of points. Thorough discussions of
these techniques are given by Morrison
(1967), Harman (1967), and Pielou (1969).

RESULTS AND DISCUSSION

Principal component analysis is a useful
tool for simplifying complex data sets and
identifying latent regularities. It has been used
extensively in vegetational studies (e.g.,
Austin, 1968; Peet & Loucks, 1977) where
each collection site is characterized by its
species composition. | applied principal com-
ponent analysis based on the correlation
matrix of the five environmental variables

MULTIVARIATE ANALYSIS OF SNAIL DISTRIBUTION 203

TABLE 2. Correlations among environmental variables. Elements of the matrix above the diagonal are
simple correlation coefficients, while those below the diagonal are partial correlation coefficients.

Altitude Aspect
Altitude 1.00 —.236**
Aspect — ,192* 1.00
Angle .104 ner
Substrate —.026 —.085
Cover .023 —.037

Angle Substrate Cover
ТУ —.026 .000
—.306** —.085 —.097
1.00 —.268** —.196”
—.200* 1.00 795%
.011 807° 1.00

*Significant at the 95% confidence level.
**Significant at the 99% confidence level.

(BMDP4M, Dixon, 1977) to the 129 sample
sites. Factors were rotated orthogonally to
maximize the variance.

Both simple and partial correlation coef-
ficients (all other variables held constant) are
presented in Table 2. There is a very high
positive correlation between cover and sub-
strate, demonstrating that those sites with
high vegetational coverage tend to have dirt
and humus below. There is also an inverse
correlation between substrate and slope
angle, reflecting the tendency of dirt and
humus to collect in flat areas and the tend-
ency for rocks to be exposed on steeper
slopes. The correlation between cover and
slope angle disappears in the partial correla-
tion analysis, suggesting that this correlation
is secondary to the one between substrate
and slope angle. The high correlations be-
tween slope angle and slope aspect, and be-
tween slope aspect and altitude reflect pecul-
iarities of Arch Canyon. The canyon’s north-
facing slope is dissected by several steep
washes, and at high elevations the canyon
itself steepens and turns toward the south
making south-facing sites rare. Hence higher
elevations and higher slope angles both tend
to have lower (more northerly) slope aspects.

Two principal components had eigenvalues
greater than one, and together they account-
ed for 67.5% of the total variance. The factor
loadings on these two principal components
(PC’s) are presented in Table 3, and the 129
sample sites are plotted by their factor scores
in Fig. 1. Notice that substrate and cover are
very highly loaded on PC 1 and relatively un-
important in PC 2, while slope aspect and alti-
tude are highly correlated with PC 2 but not
with PC 1. Fig. 1 shows that snail-containing
sites had uniformly high PC 1 scores but oc-
cupied the range of PC 2. This suggests that
snails can be found at almost all elevations
and all slopes within the canyon, but they

localize at places with high vegetational cover
and humus.

To verify this result, | employed stepwise
discriminant function analysis (BMDP7M,
Dixon, 1977) on the 41 snail-containing sites
versus the 88 sites without snails. Strahler
(1978) used a similar technique to investigate
the relationship between woody plant species
and underlying rock type. Percent cover and
substrate were the only two variables with any
power to identify snail-containing sites, and
once the cover variable was entered into the
function, the discriminating power of substrate
was rendered insignificant. Table 4 shows the

TABLE 3. Factor loadings on the first 2 principal
components in analysis of 129 sample sites.

PC 1 PC 2
Altitude —.123 —.630
Slope aspect .013 .799
Slope angle —.489 —.579
Substrate .924 —.176
Cover .901 —.231
Eigenvalue 1.92 1.45
% variance explained

(cumulative) 38.4 67.5

TABLE 4. F ratios for environmental variables in
discriminant function analysis of snail presence.

At outset
of stepwise After
procedure first step
Vegetational
cover 52.27 entered
Substrate 42.84 2.62
Slope angle 3.76 .76
Slope aspect 3.38 2.14
Altitude 1.42 1.99
Degrees of
freedom 1 and 128 1 and 127

204 DILLON

PC2 Elevation decreasing, slope more southerly

PC1 Vegetation increasing, soil more organic

FIG. 1. Principal component analysis of environmental variables at 129 sample sites. Darkened points are
samples that contained snails.

F ratios for the five variables at the outset of
the discriminant function analysis and the F
ratios of the four remaining variables after
“cover” was entered in the first step of the
procedure. On the basis of vegetational cover
alone snail presence can be predicted in all
sites with 78% accuracy (Fig. 2). Altitude,
slope angle, and slope aspect were not
demonstrated to have any significant influ-
ence on the presence of snails at small sites
in Arch Canyon.

Stepwise discriminant analysis was also
used to identify differences in the distributions
of Sonorella and Discus within the canyon.
The occurrence of each species in any par-
ticular site was weighted by its abundance at

that site. Discriminant analysis has been used
widely in studies of community structure
(M'Closkey, 1976; Dueser & Shugart, 1978).
Green (1971, 1972) used multiple discrimi-
nant analysis to determine the factors impor-
tant in separating the habitats of 10 species of
freshwater bivalves. Harner & Whitmore
(1977) have proposed methods to calculate
niche overlap from discriminant function
scores. They used the program BMDO7M to
rank 10 environmental variables by their abil-
ity to discriminate between bird species pairs.

| obtained a discriminant function significant
at the 99% confidence level (F=13.4, d.f.=
2, 97) capable of classifying 72% of the cases
correctly. The F ratios for variables not in-

MULTIVARIATE ANALYSIS OF SNAIL DISTRIBUTION 205

35
on
®
=
Ф
© 20
©
E
3 10
zZ
5

0 25 50

75 100

Percent vegetational cover

FIG. 2. Histogram showing the 129 sample sites categorized by their percent vegetational cover. Snail-

containing sites are darkened.

TABLE 5. F ratios in discriminant function analysis of Discus and Sonorella distribution.

At outset of

stepwise procedure

Slope angle 20.25
Substrate 10.71
Slope aspect 8.13
Altitude 5:51
Vegetational cover ln)
Degrees of freedom 1, 99

cluded in the function are listed for each step
in Table 5. Slope angle was the best discrimi-
nator between the two species. Fig. 3 shows
that Sonorella is found on significantly steeper
slopes than Discus (P < .001, Mann-Whitney
U test). One likely explanation for the differing
abundances of the two species on different
slope angles involves the great difference in
their sizes. An average Sonorella has a shell
19 mm in diameter while a typical Discus has
a shell only 4 mm across. Thus Discus can
find adequate shelter during dry periods in
interstitial spaces of the humus that collects in
flat areas, but Sonorella requires rocks more
common on steeper slopes. In the course of
this survey, individuals of Sonorella were in-
deed found most frequently under rocks,

After After
first step second step
entered entered

5.56 entered

27, .41

.95 .40

.08 .92
1, 98 1, 97

while Discus was most often encountered
white sifting through deep, loosely packed
humus.

Table 5 shows that the substrate variable
also had significant discriminating power even
after “angle” was entered into the function
(Discus scores higher, as expected). It is im-
portant to notice, however, that the cover
variable had no discriminating power, even
though cover and substrate are very highly
correlated (Table 1). Cover, it has been
demonstrated, is a good predictor for the
presence of both species. But apparently
Discus is to be expected where the vegetation
grows in flat areas so that humus ассити-
lates, while Sonorella is most common in the
few places where vegetation grows on steep-

206 DILLON

30

D
o

>
So

Percent individuals
o

D

0 5 10

30 40 50

Slope angle

FIG. 3. Abundance of Discus and Sonorella at sites of varying slope angle. Sonorella is darkened and

Discus is left unshaded.

er slopes and humus does not collect, leaving
rocks and cobble exposed. Differences of this
nature decrease the probability that individ-
uals of different species occur at the same
site, and thus could reduce competition.

ACKNOWLEDGEMENTS

| thank Richard |. Yeaton and Richard
Bierregaard for providing advice and criticism
of the manuscript. A special acknowledge-
ment goes to Robert E. Ricklefs for his guid-
ance throughout the project. Computer fund-
ing came from the Department of Biology,
University of Pennsylvania. Mario Gonzeles-
Espinosa translated the abstract into Spanish.
This study was completed while the author
held a National Science Foundation graduate
fellowship.

LITERATURE CITED

AUSTIN, M. P., 1968, An ordination study of a chalk
grassland community. Journal of Ecology, 56:
739-757.

BOYCOTT, A. E., 1934, The habitats of land Mol-
lusca in Britain. Journal of Ecology, 22: 1-38.
BURCH, J. B., 1955, Some ecological factors of the
soil affecting the distribution and abundance of
land snails in eastern Virginia. Nautilus, 69: 62-
69.

CAMERON, R. A. D., 1978, Differences in the sites

of activity of coexisting species of land mollusc.
Journal of Conchology, 29: 273-278.

DIXON, W. J., 1977, BMDP Biomedical Computer
Programs. University of California Press,
Berkeley.

DEUSER, R. D. & SHUGART, H. H., Jr., 1978,
Microhabitats in a forest-floor small mammal
fauna. Ecology, 59: 89-98.

GREEN, R. H., 1971, A multivariate statistical ap-
proach to the Hutchinsonian niche: bivalve mol-
luscs of central Canada. Ecology, 52: 543-556.

GREEN, R. H., 1972, Distribution and morphologi-
cal variation of Lampsilis radiata (Pelecypoda,
Unionidae) in some central Canadian lakes: a
multivariate statistical approach. Journal of the
Fisheries Research Board of Canada, 29: 1565-
1570.

GRIME, J. P. & BLYTHE, G. M., 1969, An investi-
gation of the relationships between snails and
vegetation at the Winnats Pass. Journal of Ecol-
ogy, 57: 45-66.

HARMAN, H. H., 1967, Modern Factor Analysis.
Ed. 2. University of Chicago Press, Chicago.
HARNER, EJ. & WHITMORE, В. C., 1977, Multi-
variate measures of niche overlap using dis-
criminant analysis. Theoretical Population Biol-

ogy, 12: 21-36.

KARLIN, E. J., 1961, Ecological relationships be-
tween vegetation and the distribution of land
snails in Montana, Colorado, and New Mexico.
American Midland Naturalist, 65: 60-66.

M'CLOSKEY, В. T., 1976, Community structure in
sympatric rodents. Ecology, 57: 728-739.

MORRISON, D. F., 1967, Multivariate Statistical
Methods. McGraw-Hill, New York.

РЕЕТ, В. К. & LOUCKS, O. L., 1977. A gradient

MULTIVARIATE ANALYSIS OF SNAIL DISTRIBUTION 207

analysis of southern Wisconsin forests. Ecology, STRAHLER, A. H., 1978, Binary discriminant

58: 485-499. analysis: a new method for investigating spe-
PIELOU, E. C., 1969, An Introduction to Mathe- cies-environment relationships. Ecology, 59:
matical Ecology. Wiley-Interscience, New York. 108-116.
RESUMEN

ANALYSIS MULTIVARIADO DE LA DISTRIBUCION DE LOS CARACOLES
DEL DESIERTO EN UN CANON DE ARIZONA

Robert T. Dillon, Jr.

El análisis discriminatorio múltiple y el análisis de componentes principales resultaron bastante útiles
para interpretar la distribución de dos especies de caracoles en un cañón desértico. En sitios
pequeños, elegidos al azar, es posible predecir con precisión la presencia y abundancia de las
especies a partir de las siguientes variables ambientales: altitud, ángulo de la pendiente, orientación de
la pendiente, porcentaje de cobertura vegetal y tipo de substrato. Aunque la correlación entre las
variables ambientales fue alta, la cobertura vegetal explicó la mayor parte de la varianza en la presen-
cia de las especies. La orientación y ángulo de la pendiente, y la altitud, no afectan la presencia de las
especies cuando se les considera en forma independiente de la vegetación. Las dos especies que
viven en el cañón, Discus cronkhitei y Sonorella baboquivariensis cossi, difieren significativamente en
sus preferencias en substrato y ángulo de la pendiente. Se sugiere que Sonorella fue encontrada más
frecuentemente en pendientes rocosas inclinadas debido a que requiere la protección de las rocas.
Discus, una especie mucho más pequeña, puede encontrar abrigo adecuado en humus suelto y así
habitar en pendientes más leves, donde el humus se puede acumular.

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: MALACOLOGIA, 1980, 19(2): 209-225

MOLLUSCAN DISTRIBUTION PATTERNS ON THE CONTINENTAL SHELF
OF THE MIDDLE ATLANTIC BIGHT (NORTHWEST ATLANTIC)

David В. Franz! and Arthur $. Merrill2

ABSTRACT

A zoogeographic analysis of the inner continental shelf fauna of the Middle Atlantic Bight
(Cape Cod, Massachusetts, to Cape Hatteras, North Carolina, U.S.A.) is presented based on the
geographical and depth distributions of 184 mollusk species collected by the R/V DELAWARE II
in 1960 (Cruise 60-7). The Middle Atlantic Bight fauna contains fewer than 4% of species
endemic to this zone, and is composed of a mixture of northern and southern species. The
former comprises two faunal groups: an Arctic-Boreal group containing species which extend
northward into arctic waters, and a Boreal group, which reaches northern limits near the south of
Labrador. Species of both faunal groups reach their southern limits in the Middle Atlantic zone.

The faunal component of predominantly southern species is designated the Transhatteran
faunal group, a term which emphasizes the capability of these species to transgress the eco-
logical barrier of Cape Hatteras.

Many arctic-boreal and boreal species exhibit submergence south of Cape Cod, i.e. they track
cold isotherms into the deeper shelf waters. Species showing submergence tend to be amphi-
atlantic in distribution. Endemic boreal species generally do not show submergence in the
Middle Atlantic Bight, and are thus more tolerant of warm summer temperatures which charac-
terize the inshore waters of this area. Transhatteran species do not show submergence, al-
though they are variable in their depth distributions.

INTRODUCTION

The molluscan fauna of the Middle Atlantic
Bight of the United States is reasonably well
known, and Coomans (1962) has recently re-
analyzed this fauna in the framework of pro-
vincial zoogeography. The continental shelf
zone bounded on the north by Cape Cod,
Massachusetts, and on the south by Cape
Hatteras, North Carolina, is the Virginian Sub-
province (Dana, 1853; Johnson, 1934; Hazel,
1970) which, together with the Carolinian Sub-
province to the south, comprise a major mol-
luscan province, the Transatlantic Province
(Woodward, 1851-1856; Johnson, 1934). The
molluscan fauna of the Virginian Subprovince
lacks a significant endemic component
(Coomans, 1962) and is best characterized as
a zone supporting a mixed fauna of cold-toler-
ant “boreal” species, which range southward
into the zone, and warm-tolerant southern
(“Transatlantic”) species which extend north-
ward into the zone (Stephenson & Stephen-
son, 1954; Coomans, 1962; Powell & Bous-
field, 1969).

The marine environment of the shallow con-
tinental shelf of the Virginian zone is subjected

to extreme seasonal temperature fluctuation;
(Sanders, 1973) which are partially amelio
rated at increasing depth. Consequently spe
cies which are eliminated by temperature con
ditions in the shallow shelf—either by seasona
extremes or by severe thermal instability—
may survive in deeper water. For “boreal’
species, which extend southward into the Vir-
ginian Subprovince, this phenomenon has
been called boreal submergence (Ekman,
1953). Likewise, warm-water species which
extend northward into the Virginian zone sur-
vive by virtue of warm summer conditions
which prevail over the inner shelf and estu-
arine areas. The successful co-occurrence of
both warm- and cold-tolerant species is made
possible by their respective abilities to repro-
duce during the summer and winter periods,
and to survive extreme temperatures during
their non-reproductive periods (Hutchins,
1947).

In this paper we propose an operational
classification of the molluscan fauna of the
Virginian Subprovince based on the analysis
of the extended geographical ranges and max-
imum depth limits of species. Depth distribu-
tion patterns in the study area are presented

Biology Department, Brooklyn College, City University of New York, N.Y. 11210, U.S.A.
2National Marine Fisheries Service, Northeast Fisheries Center, Woods Hole, MA. 02543, U.S.A.

(209)

210 FRANZ AND MERRILL

and analyzed for selected species within each
of the faunal groups. Our data indicate that
faunal groups which share similar geographic
ranges may also share similar patterns of
depth distribution in the Middle Atlantic Bight.
Both the geographical ranges and depth dis-
tribution patterns reflect differing thermal
adaptive modes, which may be correlated with
the different origins of each of the faunal
groups.

METHODS AND MATERIALS

In May, 1960, the Bureau of Commercial
Fisheries3 initiated a cruise of the R/V DELA-
WARE II (Cruise 60-7) in the Middle Atlantic
Bight from Cape Cod, Massachusetts, to Cape
Hatteras, North Carolina. One hundred and
thirteen stations were sampled at depths of 26
to 146 m (see Merrill & Franz, in preparation, in
which the distributions of all invertebrate spe-
cies are graphed along with station locations
and depths). While the primary purpose of the
cruise was to collect data on the distribution
and abundance of sea scallops, Placopecten
magellanicus (Gmelin), samples of other
macroinvertebrates were taken at each sta-
tion. Additionally, a 76.2 ст (30 in.) Digby
Dredge with 12.7 mm (% in.) liner was towed
at all stations to collect biota associated with
the scallops. These collections were frozen on
board, later thawed, sorted, identified and
tabulated ashore as time allowed.

A total of 184 species of mollusks identified
from these collections were used in the follow-
ing analysis. In addition, four species of the-
cosomatous pteropods were collected. Some
material collected in deeper waters included
non-living mollusks which today live in estu-
arine and nearshore waters. These have been
determined to be of Holocene age, deposited
during a period when sea levels were lower
than today (See papers by Merrill, Emery &
Rubin, 1965; Merrill, Davis & Emery, 1978).
Range extensions of mollusks based on this
cruise were published recently (Merrill, Bullock
& Franz, 1978).

There are several advantages in basing a
zoogeographic analysis on data from a single
cruise rather than on distributional data pub-
lished in general works such as Abbott (1954,
1974) or faunal compilations such as Dall
(1889b) or Johnson (1934). In the present
study, our analysis is based on a list of 184

3Now the National Marine Fisheries Service.

taxa, all but 8 of which were identified to spe-
cies. In addition to few taxonomic problems,
we were not confronted with the problem of
dealing with large numbers of poorly known
species with questionable distributional rec-
ords. The main advantage, however, lies in the
accurate depth and latitudinal information
which, in the present study, are combined to
produce depth distributions for selected spe-
cies among several zoogeographic groups.
However, there are limitations in the use of
cruise data. In this study, shallow stenobathic
and/or intertidal species were either not repre-
sented or under-represented because no
dredge samples were taken at depths less
than 26 m. Likewise, some small species were
probably not collected due to the systematic
sampling scheme, and the use of a dredge
liner with relatively large screen size of
12.7 тт. However, the near-shore compo-
nent of the molluscan fauna has been easier to
acquire in the past so that these species and
their patterns of distribution are better under-
stood. Published information on the near-
shore distribution of species have been com-
bined with the off-shore results of the present
study to provide a reliable summary of the
depth and latitudinal limits of many species
inhabiting the Middle Atlantic Bight. When
grouped into zoogeographic categories, the
few inaccuracies which may be present do not
significantly detract from the general conclu-
sions discussed below.

In determining distribution, we have con-
sulted the usual literature of which the major
sources are indicated by an asterisk in the
References section. This information has been
used to supplement our own work in the Middle
Atlantic area. Thus, the DELAWARE II Cruise
60-7, on which this report is based, yielded
close to 200 mollusk species (including
cephalopods) from the Middle Atlantic Bight.
At the same time, transect studies undertaken
off South Carolina produced an additional 300
species. As a result of these studies, over 100
new latitudinal ranges and some 20 significant
new depth ranges have been added to the
literature (Merrill & Petit, 1965, 1969; Merrill,
Bullock & Franz, 1978). Additional information
relative to the critical area of Cape Hatteras
was obtained through cooperation with col-
leagues at Duke University Marine Laboratory
and the Institute of Marine Sciences of the
University of North Carolina, Morehead City,
North Carolina (cf. Cerame-Vivas & Gray,

MIDDLE ATLANTIC BIGHT MOLLUSCAN DISTRIBUTIONS ZM

TABLE 1. Zoogeographic composition of the 184 species collected by the R/V DELAWARE (Cruise 60-7).

Appendix No. %

1 Northern species with distributions predominantly north of Cape

Cod, MA 42 22.8
2 Species endemic to the Middle Atlantic zone 7 3.8
3 Southern species with northern limits north of Cape Cod 22 12.0
4 Southern species with northern limits at or south of Cape Cod 60 32.6
5 Southern species with northern limits in NC 38 20.7
6 Cosmopolitan and/or eurybathic species 7 3.8
7 Unidentified species including specimens too worn or fragmented

to be identified 8 4.3

Totals 184 100.0

1966, for distributional patterns of shelf inver-
tebrates north and south of Cape Hatteras and
Porter (1974) for distribution patterns of inver-
tebrates in North Carolina coastal waters). The
collections at the National Museum of Natural
History (USNM) and the Museum of Compara-
tive Zoology (MCZ) at Harvard University have
been consulted as well as the extensive re-
search collections of the National Marine
Fisheries Service at Woods Hole, Massa-
chusetts. The mollusk materials collected dur-
ing the DELAWARE II Cruise 60-7 have been
accessioned into the mollusk collection at the
MCZ.

RESULTS

The general geographical and depth distri-
butions of the 184 species are shown in Ap-
pendices 1-7 in the following zoogeographic
categories: 1—Northern species with southern
limits north of Cape Hatteras, NC; 2—Species
endemic to the Middle Atlantic Bight; 3—
Southern species ranging south of Cape Hat-
teras with northern limits north of Cape Cod,
MA; 4—Southern species with northern limits
in the Middle Atlantic Bight at or south of Cape
Cod; 5—Southern species with northern limits
in North Carolina; 6—Cosmopolitan and/or
eurybathic species; 7—Unidentified species.

The relative proportions of these zoogeo-
graphic groups are shown in Table 1. About
23% of the Mollusca are northern species
which range predominantly north of Cape Cod,
but which reach their southern limits in the
Middle Atlantic Bight. Only seven species
(< 4%) are endemic to the Middle Atlantic
zone between Cape Cod and Cape Hatteras.
Roughly 12% is composed of warm-water
species with northern limits north of Cape Hat-

teras (Appendix 3); and 33% are southern
species with northern limits in the Middle Atlan-
tic Bight at or south of Cape Cod (Appendix 4).
The last major component is a group of warm-
water species, comprising 21%, which reach
their northern limits in North Carolina.

DISCUSSION

Zoogeographic Categories and Extended
Geographic Ranges

The faunal analysis shown in Table 1 indi-
cates that the shelf Mollusca of the Middle
Atlantic Bight form two major components: (a)
predominantly northern species whose ranges
extend south of Cape Cod, and thus into the
Middle Atlantic zone (Appendix 1); (b) pre-
dominantly southern species which range
north of Cape Hatteras. Most of the latter reach
their northward limits at or south of Cape Cod
although a significant proportion extends fur-
ther northward, to the Gulf of St. Lawrence or
Newfoundland (Appendices 3 and 4).

Only seven species collected in this survey
appear to be endemic to the Middle Atlantic
zone (Appendix 2). In some cases, the tax-
onomic status is uncertain, and it is likely that
the ranges of others will eventually be extend-
ed by further collecting. Thus, Coomans'
(1962) contention that the “Virginian” sub-
province (the coastal zone between Cape Cod
and Cape Hatteras) lacks a zoogeographically
significant level of endemic mollusks is sup-
ported by this study.

Analysis of the extended ranges of the
northern species (Appendix 1) in the northwest
Atlantic indicates that this group contains two
elements: boreal species, which reach their
northern limits in Labrador or south; and

212

arctic-boreal species, which extend poleward
into arctic waters (as defined by Dunbar,
1954). Of the species listed in Appendix 1,
approximately 69% are boreal, and 31%
arctic-boreal.

Although the precise northern limits of some
species are poorly known, it is likely that the
actual poleward limit of many boreal species is
related to the interface between arctic and
subarctic water masses as defined by Dunbar
(1954). These thermal boundaries occur on
the southeast coast of Baffin Island and in the
region of the Davis and Hudson Straits. Com-
plex thermal and other ecological barriers
operate in these areas to affect the poleward
distribution of many species. These include
maximum summer temperatures of 2-8°C,
and extremely reduced summer salinities in
shallow water due to the melting of ice.

Analysis of Appendix 1 shows that the arctic-
boreal and boreal components differ quantita-
tively in their extended geographical distribu-
tions. About 85% of arctic-boreal species are
amphiatlantic (occurring on both sides of the
North Atlantic) as compared to only 21% of
boreal species. Furthermore, nine of the 13
arctic-boreal species (69%) also occur in the
North Pacific as compared with only one of 28
(3.5%) of boreal species. These differences in
northern species suggest differences in
paleobiogeography, and are discussed in a
companion paper (Franz & Merrill, 1980).

The fauna of group (b), southern species
with northern limits north of Cape Hatteras, is
designated transhatteran in recognition of the
ability of these species to transgress the Cape
Hatteras thermal barrier, and to maintain
populations in the thermally unstable shallow
waters of the Northwest Atlantic. As seen in
Appendix Groups 3 and 4 of Table 1, these are

TABLE 2. Depth distribution of faunal groups.

FRANZ AND MERRILL

species which range southward to Florida, the
Gulf of Mexico, and in many cases into the
Caribbean and to Brazil. This is essentially an
endemic temperate/subtropical fauna. Thus, it
is evident that transhatteran species provide
the major endemic component in the geo-
graphical zone between Cape Cod and Flor-
ida, i.e. the “Transatlantic Province” of Wood-
ward (1851-56) and Johnson (1934). The two
terms are unambiguous however. The Trans-
atlantic faunal province is defined as a geo-
graphical zone (Hazel, 1970); the trans-
hatteran fauna refers to a group of species
unique in their endemicity and in their distribu-
tion across the Cape Hatteras faunal barrier.

Depth Distributions

The known depth ranges of the 184 species
collected by the R/V DELAWARE are includ-
ed in Appendices 1-6. Depth ranges, as such,
convey only limited information on depth pref-
erences of benthic species, so that generali-
zations based on these data must be con-
sidered tentative at best. Table 2 shows the
depth distributions for each of the faunal
groups represented by Appendices 1, 3, 4,
and 5. For each faunal group the percentage
of species with maximum depths falling within
five categories from < 10m to > 200m are
listed. These data suggest several tentative
generalizations. A large majority (80%) of the
northern species of Appendix Group 1 (Table
2) have depth ranges which extend into
deeper waters, i.e. greater than 100 m. Thus,
the capacity of this fauna, as a whole, to live in
relatively deep waters is correlated with the
amphiatlantic characteristic of the group, and
especially the arctic-boreal component as
noted above. Furthermore, the combination of

Appendix 1 3 4 5
Southern species
Southern species extending to Southern species
extending north or south of extending north
Northern species of Cape Cod Cape Cod to NC
Maximum RÁ MMM
depth (m) No. % No. % No. % No. %
10 0 4 21.0 1 iter, 0
10-50 3 Tho 4 21.0 12 21.0 4 10.8
51-100 5 11.9 Uf 36.8 14 24.6 8 21.6
101-200 16 38.0 1 SE 11 19.3 16 43.2
200 + 18 42.8 3 15.8 19 338 9 24.3
Totals 42 19 5% 37

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MIDDLE ATLANTIC BIGHT MOLLUSCAN DISTRIBUTIONS 213

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LATITUDE

FIGS. 1-6. Depth distribution patterns of six species collected from the Middle Atlantic Bight. All of these
species are predominantly northern in distribution but extend south of Cape Cod into the Middle Atlantic
zone. All show submergence as indicated by increasing minimum depth with decreasing latitude. All points
based on living material. Figs. 1-3 (Solariella obscura, Astarte crenata subaequilatera, Yoldia sapotilla) are
arctic-boreal; Figs. 4-6 (Buccinum undatum, Arctica islandica, Modiolus modiolus) are boreal. All but

Yoldia sapotilla are amphiatlantic.

northern geographical distributions and the
capacity to live at greater depths suggests
that these species should occur in deeper
waters farther south, a phenomenon referred
to by Ekman (1953) as submergence (boreal
and tropical submergence). Submergence is
usually considered to reflect a degree of cold
stenothermy, at least to some critical life func-
tion.

A large proportion (67%) of the warm tem-
perate/subtropical species represented in
Appendix Group 5 (Table 2) also have maxi-
mum depth ranges greater than 100 m. Thus,

this group and the arctic-boreal faunal group,
both of which extend only marginally into the
middle Atlantic zone, are able to do so by vir-
tue of their capacities to live in deeper water.
The latter (Appendix Group 1 species in Table
2) extend into the Middle Atlantic Bight by
tracking cold isotherms into deeper water; the
former (the warm-temperate/subtropical
species of Appendix Group 5, Table 2) extend
northward by tracking warm isotherms on the
continental shelf off north Carolina. Winter
temperatures inshore north of Cape Hatteras
are too cold for the survival of such species.

214 FRANZ AND MERRILL

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LATITUDE

FIGS. 7-12. Depth distribution patterns of six endemic boreal species collected from the Middle Atlantic
Bight shown in order of decreasing depth limits: Fig. 7 Astarte undata, Fig. 8 Cyclocardia borealis, Fig. 9
Crenella glandula, Fig. 10 Lunatia triseriata, Fig. 11 Astarte castanea, Fig. 12 Lunatia heros. The first three
species range northward to Labrador; the remainder reach northern limits at or south of the Gulf of St.
Lawrence. Note the absence of submergence in the Middle Atlantic zone.

The dominant fauna of the Middle Atlantic
zone is represented by Appendix Groups 3
and 4 (Table 2). As noted above, both are
transhatteran in distribution. The Group 3
species are found predominantly in shallow
water, with 42% restricted to less than 50 m
and 79% generally found in waters less than
100m. The combination of transhatteran
zoogeography and shallow depth distributions
suggest that the capacity of this faunal group
to range north of Cape Cod is correlated with
warm summer temperatures which develop in
the shallow bays and estuaries of the Gulf of
Maine and southeastern Canada (Ganong,

1890). Indeed, this group does contain the
highest proportion of shallow sublittoral spe-
cies (21% with maximum depths less than
10 m—Table 2), and includes the most char-
acteristic estuarine molluscan fauna of the
Middle Atlantic and New England regions.
Group 4 differs from Group 3 in lacking a
large proportion of shallow species; only 21%
are restricted to waters less than 50 m. Evi-
dently these temperate shelf species are un-
able to maintain populations at the cool sum-
mer temperatures which develop at their nor-
mal depth range north of Cape Cod. As noted
earlier, we combine the species of Groups 3

MIDDLE ATLANTIC BIGHT MOLLUSCAN DISTRIBUTIONS 215
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CATMTUDE

FIGS. 13-18. Patterns of depth distribution of transhatteran species in the Middle Atlantic Bight. The first
five species (Figs. 13-17): Crepidula fornicata, C. plana, Crucibulum striatum, Nassarius trivittatus and
Ensis directus, reach northern limits in shallow and estuarine waters north of Cape Cod. The last species
(Fig. 18), Anachis avara, is restricted to relatively shallow waters south of Cape Cod.

and 4 into a single faunal unit—the transhat-
teran—of which the Group 3 species can be
considered as only the very shallow shelf and
estuarine component, i.e. outliers of the main
transhatteran fauna, most of which reach
northern limits at or south of Cape Cod.
The depth distributions of selected species
based on DELAWARE cruise data from the
Middle Atlantic Bight are presented in Figs. 1
to 18. Species were selected based on the
completeness of available data, and to repre-
sent the faunal groups defined above. Figs.
1—6 show the pattern for six northern species
selected from Appendix 1. All are widely dis-

tributed, cold-water amphiatlantic species,
and all show submergence with decreasing
latitude. The pattern for Solariella obscura is
somewhat anomalous in that it was not col-
lected in the deeper stations, although this
species has been collected from very deep
water (Clarke, 1962). Astarte crenata sub-
aequilatera and Yoldia sapotilla, are also
arctic-boreal with great depth ranges. Sub-
mergence is clearly illustrated by the increas-
ing minimal depth of collection with decreasing
latitude. The remaining species, Modiolus
modiolus, Buccinum undatum and Arctica
islandica, are predominantly amphiatlantic

216 FRANZ AND MERRILL

boreal in distribution although M. modiolus
and B. undatum are known to extend mar-
ginally into arctic waters (Ockelmann, 1958;
Macpherson, 1971). In the Middle Atlantic
zone, these species are limited to relatively
shallow depths, and each shows definite
submergence. It is clear that submergence
does not necessarily imply wide depth dis-
tributions since both B. undatum and A.
islandica are restricted to depths generally
less than 100 m in the Middle Atlantic Bight.
Thus, the southward distribution of arctic-
boreal and boreal species on the shelf de-
pends on their depth limitations. Deep ranging
species may occur as far south as Cape Hat-
teras in the deep shelf (or even further in the
case of the eurybathal Astarte crenata sub-
aequilatera). Shallow boreal species such as
Modiolus modiolus and Buccinum undatum
are constrained in their seaward distribution
by unsuitable depths (or depth-related eco-
logical factors) and shoreward by critical
warm summer temperatures.

Figs. 7-12 illustrate patterns of depth dis-
tribution of six endemic boreal species (also
from Appendix 1) placed in order of decreas-
ing depth limits in the Middle Atlantic zone.
The first three, Astarte undata, Cyclocardia
borealis, and Crenella glandula, range north
to Labrador; the remaining three, Lunatia
triseriata, Astarte castanea, and Lunatia
heros, reach northern limits in Nova Scotia
and/or the Gulf of St. Lawrence. Note that
none of these endemic boreal species ex-
hibits marked submergence in the study area,
as compared with the amphiatlantic species
shown in Figs. 1 to 6. This implies that the
endemic boreal species are less sensitive to
warm summer nearshore temperatures in the
Middle Atlantic Bight.

The capacity of certain endemic boreal
species to range significantly farther poleward
than others is puzzling. As more data become
available on the depth, thermal and latitudinal
limits of boreal endemic species, it may be
possible to determine if the northward exten-
sion of species is correlated with its depth
range in the Middle Atlantic Bight. Shallow
species adapted to the thermal environment
of the shallow shelf of the Middle Atlantic
Bight may be constrained by cold tempera-
tures which occur at comparable depths in
and north of the Gulf of St. Lawrence. Alter-
nately, relatively eurybathal species, adapted
to the variable thermal environment en-
countered over a greater depth range in the
Middle Atlantic shelf, may be better adapted

to extend their ranges northward on the
Canadian Atlantic shelf.

Figs. 13-18 illustrate the patterns of
depth distribution for six transhatteran spe-
cies. The first five: Crepidula fornicata, C.
plana, Crucibulum striatum, Nassarius trivit-
tatus, and Ensis directus, range north
of Cape Cod (see Appendix 3). Note that
each occurs in waters of moderate to shallow
depths (<85m) and, indeed, these
five species are examples of transhatteran
forms which extend north of Cape Cod in
shallow bays, estuaries and coastal waters.
The last species, Anachis avara, reaches its
northern limits near Cape Cod (Appendix 4).
An epibenthic predator restricted to relatively
shallow depths (< 90 m), its northern range
limits may be determined by cold summer
temperatures on the shallow continental shelf
north of Cape Cod.

None of the other species of Appendix 4,
i.e. transhatteran species with northern limits
at or south of Cape Cod, was collected in
enough abundance, or over a wide enough
latitudinal range, to plot in the form shown in
these figures. This may seem surprising since
many of the species listed in Appendix 4 are
important components of the fauna of the
Middle Atlantic Bight (e.g. Busycon canalicu-
latum, B. carica, Mitrella lunata, Nassarius
vibex, Anadara ovalis, A. transversa, Lyonsia
hyalina, Macoma tenta, Tellina versicolor,
etc.). However. it must be remembered that
Cruise 60-7 was primarily initiated to survey
populations of sea scallops in commercial
quantities. For this reason, collecting stations
were restricted to sites deeper than 26m
since sea scallops are largely prevented from
occupying shallow sublittoral habitats due to
summer warming. North of Cape Hatteras,
the species listed above are most abundant in
shallow inshore waters and would conse-
quently be underrepresented in the R/V
DELAWARE samples. Not surprisingly, many
of the species of Appendix 4 appear more
frequently in the DELAWARE cruise stations
from the southern end of the Middle Atlantic
zone. Thus, aS more data become available,
we may find in these species a depth distribu-
tion pattern more appropriately characterized
as “boreal emergence,” i.e. a tendency for
these species to be restricted to shallower
waters north of Cape Hatteras.

The transhatteran faunal groups of Ap-
pendices 3 and 4 comprise the major mol-
luscan component of the American Atlantic
coast. This fauna is complex and ancient and

MIDDLE ATLANTIC BIGHT MOLLUSCAN DISTRIBUTIONS 217

undoubtedly contains a diversity of adaptive
strategies as regards thermal requirements,
thermal tolerance limits and depth distribu-
tions. Depth distribution patterns are not al-
ways related to temperature; and we are rare-
ly able to completely partition the various en-
vironmental factors affecting the depth dis-
tribution of a species. However, the critical
role of temperature in structuring depth pat-
terns is indisputable in many species, and
probably significant in most. We believe that
as more depth distribution data become
available over the entire latitudinal ranges of
continental shelf species, we will have a valu-
able tool for interpreting and evaluating the
faunal distinctions proposed in this and earlier
papers.

Molluscan zoogeographers have rarely
considered the origins of faunal groups as
major determinants of distribution within
marine faunal provinces. It is possible that
groups of species with similar paleogeo-
graphical histories may share similar physio-
logical requirements and tolerances—which
may be reflected in simitar distribution pat-
terns. For example, our data show that the
amphiatlantic boreal species are more vul-
nerable to warm summer temperatures—as
indicated by boreal submergence—than are
the endemic boreal species. Perhaps this is
related to the origin of the endemic com-
ponent from Cenozoic American ancestors,
with long histories in the Middle Atlantic zone.
The amphiatlantic boreal species, on the
other hand, may be derived from ancestors in
the eastern Atlantic or North Pacific—boreal
regimes of much less thermal variability than
the Northwest Atlantic. The relationships be-
tween the distribution patterns and possible
origins of faunal groups in the Northwest At-
lantic are discussed further in a subsequent
paper (Franz & Merrill, 1980).

CONCLUSIONS

Based on an analysis of the geographical
and depth distributions of 184 molluscan spe-
cies collected by the R/V DELAWARE ll
Cruise 60-7 in the Middle Atlantic Bight, the
following generalizations are suggested:

(1) Fewer than 4% of the species appear to
be endemic to the Middle Atlantic zone;
and the percentage may well be lower
should their taxonomic status and dis-
tribution be modified by further study.

(2) The fauna contains two major groups of
species. The first is made up of pre-
dominantly northern species whose
ranges extend south of Cape Cod, and
thus into the study area. This group con-
tains two components—arctic-boreal and
boreal—which differ in their latitudinai
limits, and in the proportions of amphi-
atlantic and endemic species.

(3) The second major group consists of pre-
dominantly southern species which range
north of Cape Hatteras, and thus into the
Middle Atlantic zone. This fauna is desig-
nated the transhatteran fauna in this pa-
per.

(4) A significant proportion of transhatteran
species reach their northern limits north of
Cape Cod, and occur northward to the
Gulf of St. Lawrence. These are mostly
shallow stenobathic forms which live in
shallow bays and estuaries.

(5) The majority of transhatteran species
reach northern limits at or south of Cape
Cod.

(6) Many of the arctic-boreal and boreal spe-
cies of the northern fauna show sub-
mergence in the Middle Atlantic zone, ¡.e.
they “track” cold isotherms into the deep-
er shelf waters of the Middle Atlantic
Bight. Species showing submergence
tend to be amphiatlantic in distribution.
Boreal species endemic to the Northwest
Atlantic do not show submergence in the
Middle Atlantic Bight. These differences
are related to the ability of species to tol-
erate summer temperatures in the shal-
low shelf zone, and may reflect differ-
ences in the origins of the endemic and
amphiatlantic faunal groups.

(7) Transhatteran species, while variable in
depth distributions, do not show sub-
mergence in the Middle Atlantic Bight. As
the major faunal element of the Trans-
atlantic faunal province, transhatteran
species show great diversity in depth and
thermal tolerance patterns. Further
analysis of the depth distribution patterns
of these species over their entire geo-
graphical ranges may reveal interesting
zoogeographical patterns.

ACKNOWLEDGEMENTS
The writers thank P. H. Chase, Jr., J. В.

Donovan, H. W. Jensen, and S. R. Nickerson
of the NMFS Woods Hole Biological Labora-

218 FRANZ AND MERRILL

tory for their assistance in sorting the inverte-
brates and sediments, and for logging the
volumetric contents of each Digby dredge col-
lection. The junior author of this article and
Robert C. Bullock undertook the responsibility
for species identification. They received aid
and are indebted to the following people for
assistance in identifying or confirming identifi-
cation of species within their special interests:
R. Tucker Abbott, Kenneth J. Boss, J. Lock-
wood Chamberlin, Arthur H. Clarke, William J.
Clench, Richard Foster, Donald R. Moore,
Joseph P. E. Morrison, Harald A. Rehder,
Robert Robertson, Joseph Rosewater, Ruth
D. Turner and Gilbert L. Voss.

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220 FRANZ AND MERRILL

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221

MIDDLE ATLANTIC BIGHT MOLLUSCAN DISTRIBUTIONS

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APPENDIX 2. Species endemic to the Middle Atlantic zone (Cape Cod to Cape Hatteras).

Species Geographical range Depth range (m)

Crenella fragilis Verrill, 1885 VA to NC 110-140
Marginella borealis Verrill, 1884 S. of MA to NC 64-180
Odostomia dealbata (Stimpson, 1851) MA to NY 6-73

Odostomia smithii Verrill, 1880 S. of MA 155-267
Palliolum subimbrifer (Verrill & Bush, 1897) MA to NC 37-667
Philippia n. sp. VA to NC 106-146
Turbonilla elegantula (Verrill, 1882) MA to NC 26-110

APPENDIX 3. Southern species with northern limits.

Faunal Depth Time of
Species Geographical range group* range (m) appearance
Acteocina canaliculata (Say, 1822) NS to Fla., Texas & W.l. TH 1-8 Pliocene
Crepidula fornicata (Linné, 1758) S.E. Canada to Fla., Texas TH 1-88 Miocene
Crepidula plana Say, 1822 S.E. Canada to Texas, Brazil,
Bermuda TH 1-66 Miocene
Crucibulum striatum Say, 1824 NS to both coasts of Fla. TH 6-346 Pliocene
llyanassa obsoleta (Say, 1822) Gulf St. Lawrence to N.E. Fla. TH 0-2 Pliocene
Nassarius trivittatus (Say, 1822) Newfoundland to N.E. Fla. TH 1-90 Miocene
Natica pusilla Say, 1822 Maine to Fla., Gulf states to Brazil TH 1-130
Turbonilla interrupta (Totten, 1835) Gulf St. Lawrence to W.I. TH 1-35
Crassostrea virginica (Gmelin, 1791) Gulf St. Lawrence to Gulf Mex.; W.l. TH 1-40 Pliocene ~
Cumingia tellinoides (Conrad, 1831) NS to Fla. TH 1-90 Miocene
Ensis directus Conrad, 1843 Labrador to Fla. TH 1-73 Pliocene
Gemma gemma (Totten, 1834) NS to Fla., Texas, Bahamas TH 1-30
Lucinoma filosa (Stimpson, 1851) Newfoundland to N. Fla., Gulf States TH 30-965 Pleistocene
Mercenaria mercenaria (Linné, 1758) Gulf St. Lawrence to Fla., Gulf Mex. TH 1-6 Miocene
Mulinia lateralis (Say, 1822) Maine to N. Fla., Texas TH 1-8
Nucula proxima Say, 1822 NS to Fla., Texas; Bermuda TH 1-90 Miocene
Petricola pholadiformis (Lamarck, Gulf St. Lawrence to Texas; S. to
1818) Uruguay TH 0-20 Pliocene
Tellina agilis Stimpson, 1857 Gulf St.Lawrence to GA TH 1-88 Pliocene
Thyasira trisinuata Orbigny, 1842 NS to $. Fla, W.l.; Alaska to San
Diego, CA TH 27-350
Illex illecebrosus (Lesueur, 1821) Newfoundland to N. Fla. TH Pelagic
Loligo pealeii Lesueur, 1821 NS to Fla., Texas, Venezuela;
Bermuda TH Pelagic
Rossia tenera (Verrill, 1880) NS to Texas; N. Europe ? Pelagic

"TH = transhatteran.

APPENDIX 4. Southern species with northern limits in the Middle Atlantic zone at or south of Cape Cod.

Faunal Depth Time of :
Species Geographical range group* range (т) appearance
Anachis avara (Say, 1822) MA to E. Fla., Texas TH 1-88
Aplysia willcoxi Heilprin, 1886 Cape Cod to Fla. (both coasts),
Texas to Brazil; Bermuda TH 0-?
Busycon canaliculatum(Linné,1758) MA to St. Augustine, Fla. TH 1-40 Pliocene
Busycon carica (Gmelin, 1791) MA to E. Fla. TH 1-70 Pliocene
Busycon contrarium (Conrad, 1840) NJ to Fla., Gulf States TH 1-37 Pleistocene
Cadulus carolinensis Bush, 1885 VA to Fla., Texas Th 5-183
Calliostoma bairdii Verrill &
Smith, 1880 MA to Fla. TH 37-465

Diodora tanneri Verrill, 1883 Off Delaware Bay to Barbados ? 75-730

MIDDLE ATLANTIC BIGHT MOLLUSCAN DISTRIBUTIONS 223
APPENDIX 4. (Continued)
Faunal Depth Time of
Species Geographical range group* range (m) appearance
Epitonium championi Clench &

Turner, 1952 MA to SC TH 1-70
Epitonium dallianum (Verrill &

Smith, 1880) NJ to Fla. 2, 70-350
Epitonium pourtalesi (Verrill &

Smith, 1880) NJ to off Barbados 2 80-1100
Hyalina veliei (Pilsbry, 1896) VA to Fla. TH 1-37
Inodrillia dalli (Verrill & Smith, 1882) MA to Gulf Mex. TH 35-267
Kurtziella cerina (Kurtz & Stimpson,

1851 MA to Fla.; Yucatan TH 3-55 Pleistocene
Marginella roscida Redfield, 1860 NJ to E. Fla. TH 18-241 Miocene
Mitrella lunata (Say, 1826) MA to Fla., Texas to Brazil; Bermuda TH 1-88 Pliocene
Nassarius acutus (Say, 1822) VA to Fla., Texas 10-110 Pliocene
Nassarius vibex (Say, 1822) MA to Fla., Gulf States, W.l. TH 1-37 Pliocene
Odostomia cancellata Orbigny, 1842 VA to NC; Cuba z 26-33
Olivella mutica (Say, 1822) NJ to Fla., Bahamas TH 1-146
Polinices duplicatus (Say, 1822) MA to Fla., Gulf States TH 1-58 Miocene
Pyramidella unifasciata Forbes,

1843 NJ to Gulf Mex. TH 35-2966
Sinum perspectivum (Say, 1831) NJ to Fla., Texas, W.!., Brazil,

Bermuda TH 25-70
Stilifer stimpsoni Verrill, 1872 MA to E. Fla. 1-2295
Teinostoma cryptospira Verrill, 1884 NJ to W.I. 18-275
Terebra dislocata (Say, 1822) MD to Fla., Texas, W.l., Brazil;

Redondo Beach CA to Panama TH 1-116 Pliocene
Turbonilla reticulata (C. B. Adams,

1850) VA to W.I. 2 33
Turritella exoleta (Linné, 1758) VA to W.l., Brazil TH 1-183 Pliocene
Abra lioica Dall, 1881 MA to S. Fla., W.l. TH 11-1573
Aequipecten glyptus (Verrill, 1882) S. of Mass. to Fla., Texas TH 125-425
Aequipecten phrygium (Dall, 1886) MA to Fla., W.l. TH 70-1450
Anadara ovalis (Bruguière, 1789) MA to Texas, W.l., Brazil TH 1-14 Miocene
Anadara transversa (Say, 1822) MA to Fla., Texas TH 1-37 Miocene
Anomia simplex Orbigny, 1842 MA to Fla., Texas, Brazil; Bermuda TH 1-70
Argopecten gibbus (Linné, 1758) MD to Fla., Texas, Brazil; Bermuda TH 18-366
Barnea truncata (Say, 1822) MA to Texas; Brazil; amphi-

atlantic—Senegal to Gold Coast ? 1-55
Corbula contracta Say, 1822 MA to Fla., W.l., Brazil TH 1-115 Pliocene
Corbula swiftiana C.B. Adams, 1852 MA to Fla., Texas, W.l. TH 11-823
Crassinella lunulata (Conrad, 1834) MA to Fla., Texas; Brazil; Bermuda TH 2-110 Pliocene
Cyclopecten nanus Verrill & Bush, VA to Fla., Texas, Puerto Rico,

1897 Brazil TH 40-538
Cyrtopleura costata (Linné, 1758) MA to Texas; Brazil TH 0-4 Pliocene
Dinocardium robustum (Lightfoot,

1786) VA to N. Fla., Mexico TH 3-37
Divaricella quadrisulcata (Orbigny,

1842) MA to 5. Fla., W.l., Brazil TH 2-95
Dosinia discus (Reeve, 1850) VA to Fla., Texas, Bahamas TH 1-49
Laevicardium pictum (Ravenel, 1861) VA to Brazil; Bermuda TH 12-155
Limopsis sulcata Verrill & Bush,

1898 MA to Fla., Gulf States, W.l. TH 10-650
Lyonsia hyalina Conrad, 1831 NS to SC TH 1-70 Miocene
Macoma tenta (Say, 1834) MA to S. Fla., Brazil; Bermuda 1-157
Mercenaria campechiensis (Gmelin,

1791) NJ to Fla., Texas; Cuba TH 1-36 Miocene
Myrtea lens (Verrill & Smith, 1880) MA to Brazil TH 5-850
Noetia ponderosa (Say, 1822) VA to Florida, Texas TH 1-126 Pliocene
Nuculana acuta (Conrad, 1831) MA to Texas, W.l., Brazil TH 12-410 Miocene

224

APPENDIX 4. (Continued)

FRANZ AND MERRILL

Species

Ostrea equestris Say, 1834

Pandora inflata Boss & Merrill, 1965

Pandora trilineata Say, 1822

Parvilucina multilineata (Tuomey &
Holmes, 1857)

Pecten raveneli Dall, 1898

Pleuromeris tridentata (Say, 1826)

Tellina tenella Verrill, 1874

Tellina versicolor DeKay, 1843

*TH = transhatteran

Faunal Depth
Geographical range group” range (m)

VA to Texas, W.l., Brazil TH 1-146
NJ to Fla. (both coasts) TH 48-165
VA to Fla., Gulf Mex. TH 2-44
NJ to Fla. (both coasts), Brazil TH 2
VA to Fla., Texas, W.l. TH 17-75
VA to Fla. TH 1-227
MA to Fla., Gulf States TE 1-70
RI to S. Fla., Texas, W.l. TH 3-70

APPENDIX 5. Southern species with northern limits in North Carolina.

Species
Crepidula aculeata (Gmelin, 1791)

Cyclichnella bidentata (Orbigny, 1841)
Distorsio clathrata (Lamarck, 1816)
Granulina ovuliformis (Orbigny, 1841)
Marginella eburneola Conrad, 1834
Nassarius albus (Say, 1826)

Niso aeglees Bush, 1885

Oliva sayana Ravenel, 1834

Olivella floralia (Duclos, 1853)
Phalium granulatum (Born, 1778)
Terebra concava Say, 1827

Tonna galea (Linné, 1758)

Trivia maltbiana Schwengel & McGinty,
1942

Abra aequalis (Say, 1822)
Aequipecten muscosus (Wood, 1828)
Atrina rigida (Lightfoot, 1786)

Chione cancellata (Linné, 1767)
Chione grus (Holmes, 1858)

Chione intapurpurea (Conrad, 1849)
Chione latilirata (Conrad, 1841)
Diplodonta soror C. B. Adams, 1852
Diplodonta verrilli Dall, 1899

Ervilia concentrica (Holmes, 1860)
Eucrassatella speciosa (A. Adams, 1852)
Laevicardium laevigatum (Linné, 1758)
Lucina nassula (Conrad, 1846)
Lucina radians (Conrad, 1841)
Pandora arenosa (Conrad, 1848)
Pitar fulminatus (Menke, 1828)
Plicatula gibbosa Lamarck, 1801
Semele bellastriata (Conrad, 1837)
Strigilla mirabilis (Philippi, 1841)
Tellina aequistriata Say, 1824

Tellina alternata Say, 1822

Tellina squamifera Deshayes, 1855
Tellina sybaritica Dall, 1881
Varicorbula operculata (Philippi, 1848)
Dentalium eboreum Conrad, 1846

Geographical range

NC to Fla., Texas, Brazil; Bermuda; Central Calif.

to Chile

NC to Fla., Texas; Brazil

NC to Texas, Caribbean, Brazil

NC to Fla. (both coasts), W.I.

NC to Fla. (both coasts), W.1.

NC to Fla., Texas, W.I. to Brazil

NC to Texas, W.I. to Brazil

NC to Gulf States

NC to Fla. (both coasts), W.I. to Brazil, Bermuda

NC to Texas, Brazil; Bermuda

NC to Fla., Texas to Brazil

NC to Texas, W.I. to Brazil; Mediterranean,
Indo-Pacific

NC to Fla., Caribbean

NC to Texas, W.!.; Brazil

NC to Fla., Texas to Brazil; Bermuda

NC to S. Fla., Caribbean

NC to Fla., Texas, W.!.; Brazil

NC to Fla., Texas

NC to Texas, W.!., Brazil

NC to Fla., Texas

NC to Texas, W. 1.

NC to Fla., Texas

NC to Fla. (both coasts) to Brazil; Bermuda
NC to Fla. (both coasts), W.l.

NC to Fla. (both coasts), \\.1. to Brazil, Bermuda
NC to Fla., Texas; Bahamas

NC to Fla., W.l.; Bermuda

NC to Texas; Mexico

NC to Fla., W.l., Brazil; Bermuda

NC to Fla., Texas, W.!., Brazil; Bermuda
NC to Fla., Texas, W.l., Brazil; Bermuda
NC to Texas, Caribbean, Brazil; Bermuda
NC to Texas, Brazil

NC to Fla., Texas

NC to Fla., Texas

NC to Fla., Brazil; Bermuda

NC to Fla., Texas, \\.1., Brazil

NC to Fla., Texas, W.l.

Time of

appearance

Pliocene

Miocene

Depth
range (m)

MIDDLE ATLANTIC BIGHT MOLLUSCAN DISTRIBUTIONS 225

APPENDIX 6. Cosmopolitan and/or eurybathic species.

Depth
Species Geographical range range (m)
Astarte crenata subaequilatera
Sowerby, 1854 Arctic Ocean to off Fla., N.Europe, N. Pacific 40-783
Cuspidaria obesa (Loven, 1846) Arctic Ocean to W.I., N.Europe, Mediterranean 18-4450
Cuspidaria rostrata (Spengler, 1793) Arctic Ocean to W.l. 64-3100
Hiatella arctica (Linne, 1767) Arctic Ocean to W.l., N. Europe 2-183
Limatula subauriculata (Montagu, 1808) Greenland to Puerto Rico, Alaska to Mexico,
N.E. Europe 10-1800
Macoma balthica (Linne, 1758) Arctic Ocean to off GA; N. Europe 1-400
Poromya granulata (Nyst & Westendorp,
1839) Arctic Ocean to W.l.; Mediterranean 25-2640

APPENDIX 7. Unidentified species.

Species Stations
Alvania sp. A-7
Inodrillia sp. 4-3 A24; 3-2 A31; 4-5 A-1;5 A-4; 6-7 A-5
Neaeromya sp. 8-1, 8-7-10; 3-3
Prunum sp. 4-3; 7-8 A-9
Puncturella sp. A-8
Vitrinella sp. 7-6 A-13
Astarte sp. 1-2; 6-5 A-18; 5-4; 7-6 A-15

Rossia sp. 22

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MALACOLOGIA, 1980, 19(2): 227-248

THE ORIGINS AND DETERMINANTS OF DISTRIBUTION OF
MOLLUSCAN FAUNAL GROUPS ON THE SHALLOW
CONTINENTAL SHELF OF THE NORTHWEST ATLANTIC

David В. Franz! and Arthur $. Merrill?

ABSTRACT

An analysis of the extended geographical ranges, and endemicity, of the most prominent
gastropod and bivalve species of the shallow (= 150 т) continental shelf of the northwest
Atlantic is presented. Three faunal groups, the Arctic-Boreal, Boreal and Transhatteran, broadly
overlap in the zone between Cape Hatteras, North Carolina, and northern Labrador. The hy-
pothesis that these faunal groups differ in their origins and paleoecology is examined. The
hypothesis is supported for the Arctic-Boreal and Transhatteran faunal groups. The former
consists of Pliocene trans-arctic migrants into the North Atlantic; the latter comprises species
which are derived from the Miocene/Pliocene Atlantic fauna. The Boreal faunal group is of
mixed origins, including trans-arctic migrants, species of Atlantic origins and species of Miocene
American progenitors.

Paleo-oceanographic factors are discussed in relation to the probable Pliocene emergence of
the endemic boreal component; and the glacial environment of the northwest Atlantic shelf zone
is described as it relates to the probable survival of boreal species during the Pleistocene.
Information on Holocene range adjustments is reviewed, and evidence on the re-establishment
of boreal species is presented.

The overlapping faunal groups of the northwest Atlantic shelf are discussed within the frame-
work of the traditional marine provinces of this zone. Traditional biotic provinces between Labra-
dor and North Carolina lack predictive value for continental shelf mollusks because of the broad

overlapping nature of the faunal groups.

INTRODUCTION

The marine molluscan fauna of the shallow
continental shelf (< 150m) off the northwestern
Atlantic between Cape Hatteras, North Caro-
lina, and Labrador can be viewed as three over-
lapping faunal groups (Powell & Bousfield,
1969; Clarke, 1969). The “Transhatteran”
faunal group as defined by Franz & Merrill
(1980) comprises predominantly shallow shelf
and estuarine species which are distributed
both north and south of Cape Hatteras, and
which are endemic to the American Atlantic
coast. The “Boreal” faunal group contains
both endemic and amphiatlantic species
which are distributed between Cape Hatteras
and Labrador, although many species in this
group have narrower ranges within this zone.
The third faunal group, the “Arctic-Boreal,” is
made up of predominantly pan-arctic-boreal
species which extend into Arctic waters at the
northern end of their ranges, but which reach
their southern limits on the American coast
south of Newfoundland.

Groups of species with similar geographical
ranges obviously share similar limitations.
Since the American coast is punctuated by
well known geographical/thermal barriers—
which form the basis for traditional zoogeo-
graphic classifications—it might be argued
that the faunal groups noted above merely re-
flect groups of species whose only relation-
ship is their common environmental require-
ments. Alternately, the existence of well-de-
fined faunal groups may be accounted for by
determinants unrelated to the present geo-
graphy and marine climate (Valentine, 1973).
Among these determinants, Tertiary species
diversity, Tertiary faunal migrations, Quater-
nary paleoecology, and especially Holocene
events and faunal movements must also be
considered to account for the present patterns
of distribution.

In this paper, we provide an analysis of
these faunal groups, with particular emphasis
on the boreal faunal component. We argue
that these faunal groupings are not to be con-
sidered as merely correlates of the existing

1Biology Department, Brooklyn College of the City University of New York, Brooklyn, NY 11210, U.S.A.
2National Marine Fisheries Service, Woods Hole, MA 02543, U.S.A.

(227)

228 FRANZ AND MERRILL

marine environment, nor the products, only, of
thermal/geographic barriers. Rather, these
groupings have clearcut Tertiary origins, and
we suggest that their present distribution pat-
terns are the result of environmental condi-
tions in the Pleistocene, and especially the
Holocene. Finally, we present our views sup-
porting the abandonment of traditional pro-
vincial constructs for this faunal area.

METHODS

In this paper, our goal is to re-examine the
geographical ranges of the most numerically
and ecologically prominent mollusks of the
northwest Atlantic continental shelf, and to
classify these data so as to reveal patterns
which may be related to the origins of faunal
groups. The decision to restrict this analysis
to numerically and ecologically important
species is necessitated by the considerable
lack of information on the distributions of
many less well known northwest Atlantic
species.

The zone of primary concern in this study is
the continental shelf of the northwest Atlantic
between northern Labrador (60°N) and Cape
Hatteras, North Carolina (35°N). In general,
we have not considered species which occur
predominantly in the deep continental shelf
(>150 m) and continental slope, even though
some of these may extend into the shallow
shelf zone. Likewise, species with primarily

high arctic distributions are not treated even
though some of these reach their southern
limits on the Labrador coast.

Species included in this analysis (listed in
Appendices 1-5) have been assigned to zoo-
geographic categories (Franz & Merrill, 1980)
as follows: Arctic-Boreal gastropods (Appen-
dix 1), Arctic-Boreal bivalves (Appendix 2),
Boreal gastropods (Appendix 3), Boreal bi-
valves (Appendix 4), Transhatteran gastro-
pods and bivalves (Appendix 5). The assign-
ment of species to one of these faunal cate-
gories has been based on the extended geo-
graphical ranges of each species, as indi-
cated by published sources, including Dall
(1903), Johnson (1934), Thorson (1941),
Madsen (1949), Ockelmann (1958), Mac-
pherson (1971), Abbott (1974), Clarke (1974)
and Porter (1974). Other sources of published
information are listed in an earlier paper
(Franz & Merrill, 1980).

RESULTS

Several aspects of the macrodistribution of
the arctic-boreal and boreal groups based on
Appendices 1—4 are summarized in Table 1.
The transhatteran group is not included since
all of these species are restricted in their dis-
tribution to the northwest Atlantic. The arctic-
boreal fauna is ubiquitous—81% of these
species are amphiatlantic, only 8% are
endemic to the northwest Atlantic and the

TABLE 1. Macrodistribution of Northwest Atlantic Arctic-Boreal and Boreal Mollusks.

qq ——

Gastropods Bivalves Total
ARCTIC-BOREAL FAUNA No. % No. % No. %
Endemic to the NW Atlantic 2 4.8 4 12.5 6 8.1
Amphiatlantic 36 85.7 24 75.0 60 81.1
Amphiatlantic/Pacific 2, 75.0 22 91.7 49 81.7
Amphiatlantic but not Pacific 9 25.0 2 8.3 11 18.3
Pacific but not NE Atlantic 4 9.5 4 12:5 8 10.8
Total: Gastropods—42
Bivalves —32
Gastropods Bivalves Total
BOREAL FAUNA No. % No. % No. %
Endemic to the NW Atlantic 13 59.1 20 69.0 33 64.7
Amphiatlantic 9 40.9 9 31.0 18 35.3
Amphiatlantic/Pacific 2 22.2 4 44.4 6 338
Amphiatlantic but not Pacific 7 77.8 5 55.6 12 66.6
Pacific but not NE Atlantic 0 = 0 — —

ORIGINS AND DETERMINANTS OF MOLLUSCAN FAUNAL GROUPS 229

remaining 11% occur both in the north Pacific
and northwest Atlantic. The boreal fauna, on
the other hand, shows a much higher level of
endemic species (65%), the remaining 35%
being amphiatlantic. Of the 18 amphiatlantic
boreal species, 12 (67%) are restricted to the
Atlantic as compared to only 18% of the am-
phiatlantic arctic-boreal species. In contrast to
the arctic-boreal group, all of the boreal spe-
cies with north Pacific distributions are also
amphiatlantic, i.e. there are no boreal species
which occur in the Pacific and the northwest
Atlantic which do not also occur in the north-
east Atlantic.

The distributions of the three faunal groups
in the zone between Cape Hatteras (35°N)
and northern Labrador (60°N) are shown in
Fig. 1. In constructing these curves, we have
assumed that all species are geographi-
cally continuous within appropriate habitats
throughout their ranges.

100 O—O—O—O—O—O—O—O

OARCTIC-BORE AL
©BOREAL

BERGEN FRESSEN

60 59.57. 552 SoD)

eTRANSHATTERAN

49 47 45 43 4

Northern Limits of Transhatteran Species

Transhatteran species decline sharply in
the Cape Cod area. Over 80% of a sample of
35 transhatteran bivalve species collected by
the R/V DELAWARE extended northward to
Cape Cod (41°-42°N); but north of Cape
Cod this drops to about 30% (Fig. 1). North of
the Gulf of St. Lawrence (48°N), the remnants
of this faunal group rapidly disappear. Indeed,
transhatteran species north of Cape Cod are
generally confined to shallow bays and estu-
aries where warm summer temperatures al-
low reproductive success (Ganong, 1890).

Southern Limits of the Boreal
and Arctic-Boreal Faunal Groups

The Cape Cod area (latitude 41° — 42°N) is
a major environmental barrier to the south-
ward distribution of arctic-boreal species (Fig.
1). Although about 25% of arctic-boreal spe-

ae
IN

390372351235

PAT UDE ENORME

FIG. 1. The geographical distributions of three faunal groups of bivalves occupying the inner continental
shelf of the Northwest Atlantic between Cape Hatteras (35°N) and Northern Labrador (60°N). The ordinate
indicates the percent of all species in each faunal group present at latitudes between 35° and 60°N. These
Curves are based on the geographical ranges of species listed in appendices 2 and 4 and 5.

230 FRANZ AND MERRILL

cies range south of Cape Cod, these exhibit
marked “boreal submergence” as they track
cold isotherms into deeper water (Franz 8
Merrill, 1980).

The majority of boreal species (ca. 70%)
extend south of Cape Cod, some continuing
to Cape Hatteras, North Carolina (Fig. 1). The
amphiatlantic boreal species show boreal
submergence in this zone, a tendency much
less evident among the endemic boreal spe-
cies (Franz 4 Merrill, 1980).

Geographical Limits of the Boreal
Faunal Group

The latitudinal limits of the boreal group (Fig.
1) occur within the zone between Cape Hat-
teras and Labrador although, as noted later, a
few boreal species may establish viable popu-

YA
E

100
AMPHIATLANTIC

a

059

Pence epee Sehhr
O

60° 5957 , 55,153 , Sl

LATITUDE. -

49 47 45 43 4

lations farther north. Fig. 1 also illustrates the
optimal success of the boreal group in the geo-
graphic zone in which both the arctic-boreal
and transhatteran groups exhibit severe de-
clines in representation.

DISCUSSION

Range Limits of the Boreal Faunal Group

Unlike the arctic-boreal and transhatteran
groups, which are highly amphiatlantic and
exclusively endemic respectively, the boreal
group contains an endemic and amphiatlantic
component. The distributions of these com-
ponents for gastropods and bivalves are
shown in Figs. 2 and 3. Although 46% of en-
demic boreal gastropods range as far south

O

\

à

39 37 35535

“NORTH

FIG. 2. Frequency distribution of the endemic and amphiatlantic components of boreal gastropod species

(based on appendix 3).

ORIGINS AND DETERMINANTS OF MOLLUSCAN FAUNAL GROUPS 231

100
E AMPHIATLANTIC
=

LL]

N

Ш]

Pr

a

E 50
2

11]

O

ie

Ш]

(5

O ES

49 47 45 43 4

EMB

Nene mic

39 37 35255

“NORTH

FIG. 3. Frequency distribution of the endemic and amphiatlantic components of boreal bivalve species

(based on appendix 4).

as Cape Hatteras as compared with 11% of
amphiatlantic species, neither component
maintains permanent populations south of
Cape Hatteras. For bivalves, both the endem-
ic and amphiatlantic components are very
similar, with no species extending south of
Cape Hatteras. The optimal geographic
ranges of both components coincide (31”-—
47°N). However, for both gastropods and bi-
valves, a significantly larger proportion of
amphiatlantic species reach their northern
limits on the Labrador coast as compared with
endemic species; and the endemic compo-
nent is clearly skewed toward the southern
end of the range. On the average, endemic
species of bivalves have a range of 16 de-
grees of latitude as compared with 22 de-
grees for the amphiatlantic group. Endemic
gastropods range over about 11 degrees of
latitude, compared to about 14 degrees for
the amphiatlantic component.

There may be significant differences be-
tween boreal gastropods and bivalves (Fig.
4). Note that a greater proportion of the
amphiatlantic gastropods reach their northern
limits in Labrador (55° — 60°N) than bivalves,
due largely to the high degree of eurytopy

among littoral gastropods, particularly the lit-
torines, Lacuna and Nucella. Jackson (1974)
also emphasized that shallow, infaunal mol-
lusks (bivalves) were more eurytopic and had
wider geographical ranges than sublittoral
species. In the endemic bivalves (Fig. 4), a
somewhat larger proportion reach their north-
ern limits on the Labrador coast than gastro-
pods, but the validity of this observation
needs further confirmation because the pre-
cise northern limits of some of these species
are not known. It is likely, however, that some
of the endemic predaceous gastropods rep-
resented by this graph are linked trophically to
the productive, shallow “fishing banks”
(Grand Banks, Georges Banks) off northern
New England.

Marine Climate and the Distribution of
Arctic Boreal and Boreal Species

The poleward range limits of boreal species
are generally thought to be correlated with the
subarctic/arctic oceanographic interface,
which, as discussed by Dunbar (1951, 1954,
1968), occurs on the eastern coast of Baffin
Island, and in the area of the Hudson Strait.

232 FRANZ AND MERRILL

AMPHIATLANTIC GASTROPODS

NUMBER OF SPECIES

S60 59 57 55 53 5 49 47 45

LATITUDE - °NORTH

FIG. 4. Frequency distribution of the northern limits of the endemic and amphiatlantic components of boreal
gastropods and bivalves (based on species listed in appendices 3, 4).

ORIGINS AND DETERMINANTS OF MOLLUSCAN FAUNAL GROUPS 233

Southward, including the southeastern coast
of Baffin and the entire coast of Labrador to
the Grand Banks (as well as western Green-
land), subarctic oceanic conditions prevail to
a depth of about 200m. Such waters are
characterized by summer temperatures usu-
ally above 2°C, vertical thermal instability, and
long periods free of ice during the summer
months. Arctic conditions prevail to the north
and west, with summer surface temperatures
normally in the 1 - 2°C range (up to 8° in Hud-
son Bay) while temperatures in deeper water
range from —1 to —2°C (Andrews, 1972).

The arctic/subarctic marine interface marks
the poleward limits of the more cold-tolerant
of boreal species, and the boundary is partic-
ularly dramatic for littoral species, as reported
by Ellis & Wilce (1961) on the southeast coast
of Baffin Island (66°N). The relative roles of
temperature, reduced salinity and sea ice are
not easily distinguishable in these areas. One
boreal species which extends poleward be-
yond the subarctic boundary areas is Mytilus
edulis which has been found in Hudson Bay,
and as far north as Pond Inlet, northeast Baf-
fin Island (Ellis & Wilce, 1961).

The relationship between boreal, arctic-
boreal and arctic species and the arctic/sub-
arctic marine climatic zones is particularly
striking in West Greenland where thermal
gradients are gradual, and the subarctic
mixed zone extends farther northward due to
the warming influence of the West Greenland
Current (Ellis, 1960). On this coast, for ex-
ample, boreal opisthobranch mollusks occur
as far northward as Upernivik at 73°N
(Lemche, 1941).

Origins of the Faunal Groups

Scarlato (1977) hypothesized that the opti-
mum temperature for survival, and especially
reproduction, is precisely fixed within faunal
groups, and that these thermal characteristics
are ‘stimulated by the condition under which
the corresponding groups of species origi-
nated...” (Scarlato, 1977). This hypothesis
can be restated for application to the north-
west Atlantic faunal groups as follows: The
three major, overlapping groups (arctic-
boreal, boreal, transhatteran) comprise sets
of species with similarities in thermal limits,
thermal requirements, and thermal adaptive
strategies which reflect similarities in the ori-
gins of these species in space and time.

The Arctic-Boreal Faunal Group

Scarlato's hypothesis finds strong support
in the arctic-boreal group. The Pacific origin of
this fauna via the Arctic Ocean is emphasized
in the works of Soot-Ryen (1932), Ekman
(1953), Nesis (1961), MacNeil (1965), Durham
& MacNeil (1967), Strauch (1972), and Briggs
(1974). Einarsson, Hopkins & Doell (1967)
have shown that the Bering Strait opened dur-
ing the late Pliocene or early Pleistocene and
that transarctic migrations of Pacific species
into the Atlantic may have taken place one-
half to one million years prior to the first glaci-
ation.

Einarsson (1964) indicates the probable
fate of the majority of these transarctic mi-
grants during the subsequent glacial periods.
Of eighteen Pacific species known from the
early Pleistocene “Cardium groenlandicum”
zone of the Tjôrnes beds of Iceland, only
seven are part of the present Icelandic fauna,
all arctic or arctic-boreal species. By infer-
ence, eurybathyic arctic-boreal species prob-
ably survived by maintaining populations, at
depth, in the north Atlantic Basin, while shal-
low arctic-boreal and boreal species probably
became extinct (as in Iceland) or survived by
extending their ranges southward into glacial
refugia.

Thus, the existing, largely pan-arctic-boreal
fauna comprises a set of species which mi-
grated from the Pacific during the late Plio-
cene to early Pleistocene and which survived
the glacial episodes in the North Atlantic
either in glacial refugia (boreal and boreal-
arctic shallow species) or, in the case of pre-
dominantly arctic species, in the subpolar
arctic sea.

Nesis (1961) has suggested that species
which are distributed both in the north Pacific
and northwest Atlantic, but do not occur east
of Greenland, may have migrated into the
northwest Atlantic via the Canadian Archipel-
ago during the post-glacial climatic optimum
(PGCO). Presumably, their continued east-
ward dispersal has been blocked by the East
Greenland depth barrier (Clarke, 1973). The
species included by Nesis are: Amicula
vestita, Neptunea Iyrata decemcostata,
Yoldia myalis, Megayoldia thraciaeformis,
Cardita granulata, and Spisula polynyma.
Ockelmann (1954) believes that Megayoldia
myalis originated in the Atlantic Ocean and
migrated into the North Pacific. Neptunea
lyrata decemcostata occurs in deposits of

234 FRANZ AND MERRILL

Sangamon Interglacial age in the Northwest
Atlantic (Clarke, Grant & Macpherson, 1972)
and in lower Pleistocene deposits in Iceland
and is considered to have migrated into the
Atlantic via the Arctic during the late Pliocene
Beringian transgression (Nelson, 1978).
Cardita granulata occurs in Miocene deposits
from Maryland (Dall, 1904). Therefore, these
two species at least are not Holocene trans-
arctic migrants. The migration of shelf species
form the Pacific to the Atlantic in late glacial
times is highly questionable. Even assuming
that the Arctic Ocean was free of pack ice
during the post-glacial climatic optimum, re-
duced surface salinity would have been a bar-
rier to the dispersal of boreal species. As
pointed out by Herman (1974) salinity reduc-
tions during these ice-free periods probably
assume greater ecological importance for the
survival of invertebrates than the very modest
temperature increases. In the case of the
species indicated by Nesis, it is difficult to ac-
cept that thermal conditions suitable to the
establishment of these species were present
on the Arctic continental shelf north of Can-
ada during the Holocene.

Boreal Faunal Group

Approximately 35% of boreal species are
amphiatlantic, of which about half have fossil
and/or Recent distributions in the North Pacif-
ic. Some of these are considered to be of Pa-
cific origin, and to have migrated into the At-
lantic via the Arctic at one or more times since
the Pliocene. Among these species are Mya
arenaria, Macoma balthica, Mytilus edulis
and Neptunea despecta (Durham & MacNeil,
1967). Boreal species of Atlantic origin which
are thought to have migrated from the Atlantic
to the Pacific include Chlamys islandica,
Thyasira flexuosa, Yoldia myalis and Yoldia
limatula (Durham & MacNeil, 1967).

There remains an important residue of am-
phiatlantic species which apparently evolved
in the Atlantic and have survived through the
Pleistocene even though the genera are, in
some cases, known to be of Pacific origin.
These include Littorina littorea, L. obtusata,
Nucella lapillus, Buccinum undatum, Anomia
squamula, Arctica islandica, and Zirfaea
crispata. All except L. /ittorea occur in Pleisto-
cene interglacial deposits in the northwest At-
lantic (Richards, 1962; Clarke, Grant & Mac-
pherson, 1972) indicating that this subset of
the amphiatlantic boreal fauna lived in the
northwest Atlantic during the Pleistocene,

prior to the Wisconsin glaciation. The origins
of these species need to be examined on an
individual basis. Some are probably derived
from Tertiary progenitors in the North Pacific
(e.g. Zirfaea crispata, Nucella lapillus, Buc-
cinum undatum). Others may be derived from
Tethyan Atlantic ancestors, e.g. Cyrtodaria
siliqua. According to Nesis (1965) this spe-
cies entered the northwest Atlantic in the
Pliocene via shoals between Norway and
Greenland. The northeast Atlantic and arctic
populations are thought to have become ex-
tinct during the Pleistocene. A s.milar mech-
anism may account for amphiatlantic distribu-
tions of other boreal species during the Pleis-
tocene, as well as presently existing amphi-
atlantic distributions, if it is assumed that
populations were maintained on both shores
of the north Atlantic during glacial times. Be-
low, we discuss holocene environmental con-
ditions in the boreal zone during glacial maxi-
ma, and suggest the unlikelihood of survival
of at least some boreal species. It is known,
however, that boreal species were present in
northeastern Atlantic refugia during the last
glacial period. For example, in the western
Mediterranean, species such as Arctica
islandica, Modiolus modiolus, Buccinum
undatum and Chlamys islandica have been
recovered from submerged beds а
90-340 т. These have been dated using **C
at between 31,500 to 9,800 B.P. (Froget,
Thommeret & Thommeret, 1972). Tne oc-
currence of these and other boreal species in
Wisconsin glacial deposits off the American
coast have not been recorded, as far as we
know, although these species occur in post-
glacial deposits (e.g. Wagner, 1970).

The remaining, and largest, component of
boreal species is the endemic northwest At-
lantic group, which comprises about 65% of
the total boreal fauna. One of these species,
Yoldia limatula, has a fossil record in the Gulf
of Alaska (lower Pleistocene, Upper Yaga-
taga Formation, Allison, personal communi-
cation) but is considered to have migrated
from the Atlantic. A second species, Cyclo-
cardia borealis is closely related to North Pa-
cific congeners (Soot-Ryen, 1932) but is
probably of Atlantic origin. The remaining
endemic boreal species—by far the major
component—are closely related to Miocene
faunal elements of the American Atlantic
coast.

In summary, it is clear that the boreal faunal
group in the northwest Atlantic contains spe-
cies of varying origins in space and time. We

ORIGINS AND DETERMINANTS OF MOLLUSCAN FAUNAL GROUPS 235

have distinguished four components: (1)
Boreal species derived from the North Pacific
via transarctic migration. This component is
closely allied with the arctic-boreal fauna; (2)
Boreal species, derived from the Atlantic,
which migrated into the Pacific via the Arctic
Ocean, and presently maintain populations in
both the North Pacific and North Atlantic. (3)
Atlantic species, amphiatlantic in distribution,
which originated in the North Pacific. In either
case, these are species with long histories in
the Atlantic. (4) Boreal endemic species de-
rived from American Miocene ancestors (e.g.
Placopecten magellanicus, Cerastoderma
pinnulatum, Pandora gouldiana, etc.

Transhatteran Fauna

The third major faunal element in the north-
west Atlantic is the transhatteran group of
generally temperate and frequently estuarine
species which occur both north and south of
Cape Hatteras. As noted above (see also
Franz & Merrill, 1980) most of these species
reach their northern limits at or south of Cape
Cod although some occur farther north to
Nova Scotia or to the Gulf of St. Lawrence.
These species are derived from the Miocene
fauna of the American Atlantic coast. Dall
(1904) indicated that 10-20% of Maryland
Miocene species have survived to the present
(based on the Choptank, Calvert and St.
Mary’s formations) including ubiquitous and
abundant species such as Littorina irrorata,
Crepidula fornicata, C. plana, Neverita dupli-
cata, Lunatia heros, Mercenaria mercenaria,
Laevicardium mortoni and Thracia conradi.
Likewise, approximately 23% of the 116 mol-
lusk species identified by Bailey (1977) from
the Chowan River deposits in North Carolina
(Pliocene: Yorktown formation) occur as Re-
cent species in the northwest Atlantic. The
probable lineages of many Recent species
from Miocene/Pliocene ancestors have been
suggested by various authors although care-
ful analyses such as those of Gardner (1943)
on the Placopecten complex and Clarke
(1965) and Waller (1969) on the Argopecten
complex are generally lacking.

Paleo-oceanographic Developments in
Relation to the Evolution of Endemic
Boreal and Transhatteran Species

Strauch (1972) has shown that many Re-
cent boreal mollusks derived from temperate,
eurythermal Cenozoic ancestors evolved in

the Pliocene and Pleistocene in response to
changing climatic conditions, new migration
routes or geographic isolation. We believe
that this paradigm will also explain the origins
of most of the endemic boreal species as well
as those transhatteran species which at pres-
ent extend well northward in the northwest At-
lantic. The conditions which may have pre-
vailed at the time of appearance of these spe-
cies are summarized as follows:

The onset of northern hemispheric conti-
nental glaciation (3-2.5 million years ago) and
the development of the Labrador Current Sys-
tem significantly altered the thermal environ-
ment of the northwest Atlantic continental
shelf (Berggren & Hollister, 1977). Prior to
this, a warm Gulf Stream flowing northward
around Newfoundland and into the Labrador
Sea created the subtropical to warm-temper-
ate marine environment which prevailed at
the time of deposition of the Yorktown forma-
tion of Virginia and North Carolina (Hazel,
1971). Molluscan species in Miocene de-
posits from New Jersey to Florida clearly indi-
cate warm-temperate to subtropical condi-
tions (Dall, 1904; Richards, 1968) with little
evidence for a significant faunal barrier asso-
ciated with Cape Hatteras (Hecht, 1969;
Hecht & Agan, 1972) although ostracod bio-
facies studied by Hazel (1971) do converge at
Cape Hatteras.

The advent of the Labrador Current System
had the effect of displacing the Gulf Stream
seaward (to roughly its present position) and,
in conjunction with northern hemispheric cool-
ing, initiating the highly seasonal thermal
conditions which now characterize the marine
environment of the northwest Atlantic conti-
nental shelf.

The displacement of the Gulf Stream (to its
present position) set the stage for the geo-
graphical and ecological separation of mol-
luscan populations on either side of Cape
Hatteras. At this time, and in the following
Pleistocene period, natural selection favoring
cold tolerance and eurytopy acted on the sur-
viving Miocene stocks in the zone north of
Cape Hatteras. In some cases, selection op-
erated to enhance the cold tolerance of al-
ready existing species, thus increasing their
ability to survive both severe winter tempera-
tures and great seasonal variability. As a con-
sequence, these species retained their ability
to exist north of Cape Hatteras. In other
cases, selection would have produced new
species specifically adapted to the harsh con-
dition of the Northwest Atlantic (represented

236 FRANZ AND MERRILL

by the endemic component of the boreal spe-
cies listed in Appendices 3 and 4).

The specific conditions under which this
speciation occurred, rates and specific times
of speciation, the relative roles of thermal
cooling, increasing seasonal variability, and
geographic isolation as causative factors in
speciation remain to be worked out for most of
the species of this endemic boreal group. The
evolution of morphologically distinct subspe-
cies with converging geographic ranges near
Cape Hatteras (e.g. Spisula solidissima
solidissima and $. $. raveneli) and the well-
known tendency of American endemic tem-
perate species to produce ‘physiological
races” (e.g. Crassostrea virginica, Urosalpinx
cinerea) may represent different evolutionary
outcomes to the complex environmental chal-
lenges of this and subsequent periods.

The Glacial Environment and
Boreal Distributions

Little is known of the fate of boreal species,
and to a lesser extent arctic-boreal species in
the northwest Atlantic during the last glacial
maximum. Chlamys islandica, Macoma
balthica, Arctica islandica, Buccinum un-
datum, Modiolus modiolus and perhaps other
amphiatlantic boreal species probably sur-
vived in refugia in the northwest Atlantic. Un-
fortunately, the glacial shorelines which might
contain the evidence for the survival of such
species are located far at sea, near the edge
of the continental shelf; since living popula-
tions of many of the species in question live at
these same depths, it becomes difficult to dis-
tinguish fossil and Recent specimens.

The reconstruction of environmental condi-
tions during the Wisconsin glacial maximum in
the north Atlantic (McIntyre et al., 1976) does
permit some speculation on the probability of
survival of these species in the northwest At-
lantic. At 18,000 B.P., considered to be the
time of the last glacial maximum, very sharp
ocean thermal gradients were present at
42°N. North of this there existed a relatively
small, subpolar sea bordered on three sides
by continental glaciers and solid pack ice.
Seasonal sea temperatures ranged from 0° to
10°C in summer; and 0° to —2°C in winter.
Summer conditions in shallow water south of
42°N were dominated by dilution from melting
sea ice; the counter-clockwise gyre of surface
currents most likely transported sea ice along
the American coast in winter and early spring.

Cape Hatteras operated then, as today, in

deflecting the Gulf Stream eastward; but the
North Atlantic Drift did not occur. Rather, the
Gulf Stream flowed directly eastward across
the Atlantic. Summer sea temperatures at
Cape Hatteras ranged from 10°C in February
to 20° in August. South of Cape Hatteras,
isotherms rapidly approached existing condi-
tions, indicating that Cape Hatteras was then,
as today, a severe thermal barrier to the
southward penetration of arctic-boreal and
boreal species.

The water temperatures of the shallow shelf
between 35° and 42°N (Cape Hatteras to Cape
Cod) varied from roughly 0° - 10°C in winter,
and 10°-20°C in summer (Mcintyre et al.
1976). These would seem to be suitable tem-
peratures for the survival and reproduction of
most boreal species. However, the seaward
displacement of glacial shorelines caused a
significant reduction in the actual shelf space
available for colonization (Emery & Garrison,
1967). Sharp latitudinal thermal gradients in
this zone, superimposed on a much reduced
shelf, must have imposed a further constraint
on habitat space since it is likely that only seg-
ments of this reduced boreal zone would have
been thermally acceptable for reproduction at
any given time during the short summer sea-
son. Furthermore, it is also likely that drifting
pack ice, followed by severe dilution due to
melting, characterized the littoral zone in
spring and early summer.

These environmental constraints imposed
by glacial conditions would have put a premium
on certain adaptive characteristics: the ability
to complete reproduction over a wide temper-
ature range, the ability to disperse rapidly, the
ability to withstand reduced salinity and se-
vere winter temperatures, and in the case of
littoral species, to maintain populations in sub-
littoral habitats which would be less affected
by sea ice and meltwater. These adaptive
characteristics largely define the life strate-
gies of most existing boreal endemic mol-
lusks.

It is significant that the most prominent estu-
arine and shallow-shelf mollusks occurring
today in the zone between Cape Hatteras and
Newfoundland are species with long evolu-
tionary histories in the Atlantic, and with adap-
tive strategies favoring survival in shallow,
variable and/or estuarine conditions (e.g., am-
phiatlantic species such as Mytilus edulis,
Macoma balthica, Littorina littorea, transhat-
teran species of Miocene ancestry including
Crassostrea virginica, Urosalpinx cinerea,
Neverita duplicata, Tellina agilis, or boreal-

ORIGINS AND DETERMINANTS OF MOLLUSCAN FAUNAL GROUPS 237

endemic species of Miocene ancestry, e.g.
Lunatia heros, Spisula solidissima, Astarte
undata, Placopecten magellanicus and
Argopecten irradians). All are capable of sur-
viving thermal and salinity stress, of reproduc-
ing over a relatively wide thermal range, and
dispersing rapidly (r-strategists in the parlance
of evolutionary ecology). During the Pleisto-
cene, these traits would have permitted such
species to use portions of this boreal zone
during glacial periods, and rapidly extend
their ranges during interglacials, i.e. to track
suitable thermal and salinity conditions north-
ward with the gradual retreat of the ice pack.
This is illustrated by the fossil distributions of
the boreal bivalve Mesodesma arctatum. As
reported by Merrill, Davis & Emery (1978) this
species evidently extended its range south-
ward to at least as far as Cape Hatteras dur-
ing the glacial maximum, and contracted
northward during the Holocene, leaving fossil
evidence of its former presence in deposits
associated with specific Holocene shorelines.
Other boreal species including Astarte
undata, Cyclocardia borealis, Placopecten
magellanicus and the arctic boreal Clino-
cardium ciliatum have been collected from
core samples at a depth of 146m off New
Jersey (Ewing, Ewing & Fray, 1960).

The absence of endemic boreal rocky
shore species is not, however, accounted for
by the severe glacial conditions in this zone.
While there are endemic littoral mollusks
which presently occur in the boreal zone, all
are transhatteran in distribution, and none is
restricted entireiy to the littoral environment.
Consequently, none would have been en-
dangered by glacial conditions north of 35°N.
On the other hand, populations of some eury-
topic amphiatlantic boreo-littoral species may
very well have been excluded by these condi-
tions during glacial maxima.

Holocene Range Adjustments

The disappearance of sea ice and the final
disintegration of the great Laurentide Ice
Sheet, accompanied by massive marine
transgressions, signaled a period of intense
faunal migration and range extension which,
to a degree, is continuing to the present time.
Worldwide warming began about 14,000 B.P.
and the Laurentide Ice Sheet disintegrated
dramatically about 8,000 B.P. (Bryson et al.,
1969).The fiords of eastern Labrador were ice
free by 9,000 B.P., and Hudson Bay was
open by about 8,000 B.P. The Foxe Basin is

thought to have been ice free (Andrews,
1972) although this point is controversial
(Clark, 1971). Extensive, shallow seas of
marine to brackish water occupied the St.
Lawrence basin (Dionne, 1977) and the Otta-
wa and St. Lawrence Valleys (the Champlain
Sea) as well as southwestern Maine from
about 11,500 to 7,000 B.P. (Wagner, 1970;
Bloom, 1960, 1963). The warming trend con-
tinued until about 4,600 B.P., with a peak
about 6,000 B.P., the so-called post-glacial
climatic optimum (PGCO). Evidence suggests
that in the Canadian arctic, the marine opti-
mum lagged behind the terrestrial PGCO, oc-
curring about 3,500 B.P. (Andrews, 1972).

Evidence for the Re-Establishment of
Boreal Species

While post-glacial species movements re-
main largely unknown, information is avail-
able on the colonization of several formerly
glaciated areas by marine mollusks, and
some inference can be drawn concerning the
times and routes of migration. This informa-
tion is provided mainly by aggregations of
marine shells in raised deposits at many sites
in the Canadian Arctic, West Greenland, the
Canadian Atlantic coast and New England.
These collections usually contain a mix of arc-
tic-boreal and boreal species, indicating a
rapid re-colonization of the shallow shelf by
boreal species. The mechanisms of coloniza-
tion and the origins of these species remain
speculative.

Two sources of re-colonizing populations
are possible: boreal species may have dis-
persed from glacial refugia in the northwest
Atlantic; or, species originating on the Euro-
pean coast could have dispersed westward
via the Faeroe Islands, Iceland, and south-
west Greenland. The latter source is less like-
ly for species lacking an efficient larval or
adult dispersal mechanism but has been sug-
gested for benthic amphipods by Bousfield
(1973). This mechanism, i.e. westward dis-
persal of larvae via surface currents, is sug-
gested by Kraeuter (1974) to account for the
dispersal of Littorina littorea and is supported
indirectly by studies of larval distribution by
Mileikovsky (1968) and Scheltema (1977).
Proof of the trans-Atlantic movement of boreal
species does not exist at present, but the
possibility is supported by several lines of evi-
dence. The post-glacial recolonization of Ice-
land was effected by the westward migration
of European species (Thorson, 1941; Einars-

238 FRANZ AND MERRILL

son, 1964), and lusitanian-boreal species
such as Emarginula fissura and Acmaea
virginea, which presently reach their western
limits in Iceland (Thorson, 1941), have been
reported from Holocene raised deposits in
West Greenland (Laursen, 1950). The extinc-
tion of these less cold-tolerant boreal species
in Greenland supports the argument that at
least some boreal species extended west-
ward in post-glacial times as far as Green-
land, and that subsequent extinctions may be
correlated with thermal deterioration following
the end of the PGCO. This has also been sug-
gested to account for the disjunct amphiatlan-
tic distribution of the less cold-tolerant boreal
amphiatlantic nudibranchs (Franz, 1970,
1975). If the presently-existing boreal amphi-
atlantic fauna survived the glacial period in
refugia in the northwest Atlantic, the poleward
movement of these species in the Holocene
would present few problems. As suggested
below, the available evidence supports this
for some boreal species, but is equivocal for
others, particularly the shallow shore com-
ponent.

Evidence from Early Holocene
Transgression Faunas

The Champlain Sea transgression is be-
lieved to have lasted from about 11,500 to
between 9,000 and 8,000B.P. (Wagner,
1970). During this period, the thermal environ-
ment improved from essentially arctic condi-
tions at the beginning (Cronin, 1976, 1977) to
temperate conditions at the end, correspond-
ing to the PGCO for this area (about 9,000
years B.P.) (Schnitker, 1977). Fossil mollusks
indicative of the early arctic-subarctic condi-
tion include Portlandia arctica, Nuculana
pernula, Polinices pallidus, Mya truncata,
Buccinum hancocki, Nuculana tenuisulcata,
Висстит terrae-novae, Serripes groen-
landicus, Buccinum plectrum and Natica
clausa. Transhatteran and boreal endemic
fossils such as Haminoea solitaria, Crasso-
strea virginica, Yoldia limatula and Lyonsia
hyalina mark the terminal, temperate phase of
the Champlain Sea.

The amphiatlantic boreal component of the
Champlain Sea fauna includes Macoma
balthica, Mytilus edulis, Mya arenaria, Nep-
tunea despecta, Nucula tenuis and Chlamys
islandica.

Raised deposits containing a mixture of
arctic-boreal species from southwestern
Maine (the Presumscot Formation) are

thought to date from 11,000 to 7,000 B.P.
(Bloom, 1960). The boreal component of this
fauna includes endemic species such as
Astarte undata, Cerastoderma pinnulatum,
Mesodesma arctatum, and Spisula solidis-
sima; and the amphiatlantic species Chlamys
islandicus, Масота Баса, Висстит
undatum and Neptunea lyrata decemcostata.
The paleoecology of the Presumscot fauna—
like the early Champlain Sea—implies sub-
arctic conditions comparable, as suggested by
Bloom (1960), to the present marine climate
of Labrador.

It seems highly probable that all of the am-
phiatlantic species noted above from the
Champlain Sea and Presumcot formations
were present in the northwest Atlantic during
the Wisconsin glacial period. Macoma
balthica is a highly eurythermal estuarine
species (although it does not occur in Arctic
waters per se). Mytilus edulis, as noted by
Andrews (1972), is not restricted to intertidal
environments although it prefers shallow
water; although generally subarctic-boreal in
distribution, it has occurred recently as far
north as North Baffin Island. Chlamys island-
ica is an active species which presently lives
on the West Greenland (north to Disco Island)
and Labrador coasts, and southward to the
Gulf of Maine and Buzzards Bay. Mya
arenaria is similar to Macoma balthica in its
present distribution, being tolerant of estu-
arine conditions and subarctic temperatures.
Both Neptunea despecta and Nucula tenuis
exhibit “boreal submergence.” Neptunea
ranges from 10 m to 1203 m (Thorson, 1941)
and Nucula tenuis occurs in very deep water
as far south as Florida. Since Neptunea
despecta lacks a pelagic larval stage, it seems
likely that both of these species maintained
populations in the northwest Atlantic during the
glacial periods.

Fossil representatives of Mytilus edulis,
Macoma balthica and Chlamys islandica in
post-glacial deposits on Baffin Island (An-
drews, 1972) and west Greenland (Laursen,
1950) are considered to indicate the exist-
ence of a warmer marine environment cor-
responding to the PGCO at 4,000-3,000 B.P.
The co-occurrence of these species in post-
glacial deposits in west Greenland, the
Canadian Arctic and the Champlain Sea sug-
gests that these species may already have
been present in the northwest Atlantic, and
were able to disperse northward early in the
Holocene.

Buccinum undatum is not present in the

ORIGINS AND DETERMINANTS OF MOLLUSCAN FAUNAL GROUPS 239

Champlain Sea deposits, although it does oc-
cur in raised deposits in west Greenland
dated at 7,730B.P. (Sugden, 1973) and
Maine (Bloom, 1960). Since this species is
known from Pleistocene deposits from Labra-
dor to New Jersey (Richards, 1962) including
mid-Wisconsinan deposits (e.g. Sankaty
Head, Nantucket: Wagner, 1977) and lacks a
pelagic larval stage, it is likely that it also sur-
vived the Wisconsin glacial period in the
northwest Atlantic.

Little is Known of the origins, modes and
times of movement of other boreal amphi-
atlantic species which are not represented in
the early Holocene transgression faunas (e.g.
Arctica islandica, Modiolus modiolus,
Anomia squamula, Zirfaea crispata). Records
of Modiolus and Arctica from Sankaty Head
(Nantucket) and Tobaccolot Bay (Gardiners
Island, New York) are considered to be of late
Sangamonian or mid-Wisconsinan age
(Gustavson, 1976) but their fate during the
glacial maximum and their subsequent pat-
terns of migration are unknown.

The Shore Fauna

As noted earlier, drifting sea ice and sea-
sonal fluctuations in salinity and temperature
in the Middle Atlantic zone would have pro-
vided stringent conditions for littoral species
during glacial maxima. Major adaptive traits
conferring survival value during this period
would include: a) short annual reproductive
period, b) eurythermal reproduction, and c)
vertical mobility. Thus, species which were
able to complete reproduction during the rela-
tively short summers and to reproduce over a
wide temperature range would be more suc-
cessful in utilizing the much-reduced boreal
zone. Also, survival over the long, harsh win-
ters and spring periods of drifting sea ice and
reduced salinity would have been enhanced
by the ability to move vertically out of the lit-
toral zone.

Of the common amphiatlantic littoral spe-
cies (excluding nudibranchs which were dis-
cussed by Franz, 1975), the following prob-
ably survived the recent glacial maximum in
the, northwest Atlantic: Littorina saxatilis,
Nucella lapillus and Acmaea testudinalis.

Littorina saxatilis presently occurs from
New Jersey to the Canadian Arctic (Macpher-
son, 1971) and in post-Pleistocene deposits
in Hudson Bay, James Bay, Newfoundland,
and Quebec (Richards, 1962). Wisconsinan
records of this species and Nucella lapillus

exist from Connecticut and Long Island.
Nucella is also known from the Salmon River
(Nova Scotia) beds of mid-Wisconsinan age
(Wagner, 1977). Both of these species can
move into deeper water to avoid winter ice: L.
saxatilis from 0-94 m and N.lapillus from 0-
55 т (Thorson, 1941). This implies the pos-
sibility of the continued existence of these
species during glacial times. Acmaea testu-
dinalis presently occurs from the Canadian
Arctic (Macpherson, 1971) and on the Amer-
ican coast south to New Jersey. Although pre-
dominantly a littoral form, it survives deeper
water down to 40m (Macpherson, 1971).
Rapid dispersal is facilitated by a planktonic
veliger larva.

The available evidence suggests that the
following common littoral species may not
have survived the last glacial maximum and
were probably re-introduced in the Holocene:
Littorina littorea, Littorina obtusata and
Lacuna vincta. At present, Littorina littorea, in
its southward range expansion on the Ameri-
can coast, shows a predilection to occur freely
on sand and marsh grass; Lacuna vincta is
most abundant on Laminaria in the sublittoral.
But both species are ecologically linked to the
littoral and/or shaliow sublittoral zones and
both are unlikely to have been able to survive
winter and early spring conditions in the
boreal zone during glacial maxima. At pres-
ent, L. littorea has a disjunct amphiatlantic
distribution. It is absent in Iceland, the
Faeroes and West Greenland, but occurs in
northern Europe and the American coast from
the Gulf of St. Lawrence to Maryland (Wells,
1965). L. littorea has been found in the Sal-
mon River (Nova Scotia) deposits of pre-
sumed mid-Wisconsinan age (Wagner,
1977), and younger specimens from Nova
Scotia, New Brunswick and Newfoundland
have been dated to at least 1000 AD (Clarke
& Erskine, 1961; Bird, 1968). It seems most
likely that L. littorea dispersed via planktonic
eggs and larvae into the northwest Atlantic
during the PGCO, as suggested by Kraeuter
(1974).

Littorina obtusata offers basically the same
problems as L. littorea except that it has been
recognized as characteristic of the Canadian
Maritime and New England fauna throughout
historical times and has not undergone a sig-
nificant recent range extension. It is reported
from the Sankaty Head deposits (Nantucket)
(Clarke, Grant & Macpherson, 1972), which
are considered of late Sangamonian (Rich-
ards, 1962; Clarke et al., 1972) or mid-Wis-

240

consinan age (Wagner, 1977). According to
Thorson (1941), this species may occur to a
depth of 150m but is generally associated
with seaweeds (Fucus, Ascophyllum) in the
intertidal zone. Since the egg masses are de-
posited on seaweed, the Holocene dispersal
could be accounted for by rafted Fucus or
some other means of natural dispersal. Popu-
lations presently occur in Iceland and south-
west Greenland, suggesting the probable re-
introduction of this species in the Holocene.
This may also apply to Lacuna vincta, which
does not occur in pre-Wisconsin deposits in
North America. Its egg masses, which are
also laid on Laminaria and Fucus, release
planktonic veligers, unlike the eggs of L.
obtusata, which undergo direct development.

The final answers to the continued pres-
ence of all of these species during glacial
maxima must be sought individually for each;
perhaps the submerged shorelines of the
American Atlantic coast will yield this informa-
tion in coming years. What is certain, how-
ever, is that range expansions continue to oc-
cur, as indicated by recent rapid range modifi-
cation of Littorina littorea (Clarke & Erskine,
1961: Wells, 1965; Clarke, 1971; Кгаещег,
1974), and Rangia cuneata (Hopkins & An-
drews, 1970).

Zoogeography

The thrust of this study has been, first, to
identify groups of species which share similar-
ities in range and thermal requirements; sec-
ond, to examine the total geographical dis-
tributions of these groupings; and finally, to
consider the possibility that these groups re-
flect common origins in time and place. This
approach is similar to Petersen's (1977)
analysis of North Sea bivalves. But what rela-
tionship, if any, exists between this approach
and the traditional analysis of zoogeographic
provinces? In theory, as most recently dis-
cussed by Valentine (1973), zoogeographic
provinces are geographic areas which sup-
port faunas of relatively consistent taxonomic
composition. Adjacent provinces are sepa-
rated by geographical/thermal (or other
ecological) barriers; but there is disgreement
as to the degree of consistency required in the
recognition of distinct provinces. Obviously,
provinces defined in this way cannot overlap.
But biologisis often invert this conception of
zoogeographic provinces so that a province is
defined as the area occupied by a unique

FRANZ AND MERRILL

fauna—perceived either as some critical level
of endemicity or by some other distinctive
characteristic (e.g. the geographic region
characterized by the presence of hermatypic
corals). Zoogeographic provinces so defined
can overlap if there is geographical overlap
between two adjacent unique faunas. As
noted by Hazel (1970), this dichotomy is part-
ly to blame for the confusion in the zoogeo-
graphic terms applied to the northwest Atlan-
tic region and in the meanings of these terms.
Some malacologists, e.g. Abbott (1957), have
proposed non-overlapping zoogeographic
provinces in the classical mode; but many
other workers (Stephenson & Stephenson,
1954; Coomans, 1962; Powell & Bousfield,
1969; Franz, 1970) have recognized the sig-
nificance of the overlapping of broad faunal
groups, particularly in the “Virginian” province
(bounded by Cape Hatteras and Cape Cod).

Fig. 5 shows the relationships between the
faunal groups and the traditional, non-over-
lapping provinces as recently discussed by
Hazel (1970). Clearly, the characteristic mol-
luscan fauna associated with each province
corresponds to the three faunal groups stud-
ied in this paper; i.e. the dominant fauna of the
Syrtensian Province is the arctic-boreal; the
fauna of the Nova Scotian Province refers
primarily to the boreal; and the fauna of the
Virginian province refers primarily to the
Transhatteran faunal group. But the traditional
provinces fail as predictive tools because
each province contains two or three overlap-
ping faunal groups of very different overall
thermal strategies and origins.

Of course, the perception of the validity of
biotic provinces, no matter how defined, is af-
fected by the taxonomic groups used in the
analysis. The ostracods studied by Hazel
(1970) show relatively high proportions of
endemic species north of Cape Hatteras, thus
allowing a stronger correlation between the
classically defined provinces and faunal
groups. But the zoogeographic patterns in
shallow water gammaridean amphipods ob-
served by Bousfield (1973) and Watling (per-
sonal communication) and for polychaetes by
Kinner (1977) seem very similar to the patterns
for shelf mollusks discussed in this paper.

Ecological barriers to distribution, particu-
larly thermal/geographic barriers, are impor-
tant in all zoogeographic treatments; in the
present study, Figs. 1-3 illustrate this role in
the case of Cape Hatteras and Cape Cod. It is
possible, however, that the role of barriers in
preventing species transgressions has been

ORIGINS AND DETERMINANTS OF MOLLUSCAN FAUNAL GROUPS 241

SYRTENSIAN
100 (O)
O ARCTIC-BORE AL
© BOREAL
= e TRANSHATTERAN
Ze
LL]
Y)
LL]
A
50
=
LJ
«
X
Ш]
(5
O

NGO, 59 57:55

93. 5

49 47 45 43 4

NOVA VIRGINIAN

SCOTIAN
eo

oro © e

39737 55455

EAT |) UDB вова

FIG. 5. The geographical distribution of faunal groups (from Fig. 1) in relation to traditional biogeographic

provinces (based on Hazel, 1970).

overemphasized, with too little emphasis on
the species which are able to disregard such
barriers. This problem is exemplified by
Hecht's analysis of molluscan distribution on
the Atlantic coast from Newfoundland to Flor-
ida (Hecht, 1969). His phenograms, based on
q-mode cluster analyses, indicated three
groupings with boundaries at Cape Cod and
Cape Hatteras. He interpreted these data as
evidence supporting the concept of three
faunal provinces. However, these data also
support an alternative conclusion not consid-
ered by Hecht, viz. that the entire area between
Newfoundland and Florida is an area of over-
lap between four faunal groups, with boreal
species extending south of Cape Cod, arctic-
boreal species largely limited by the Cape
Cod thermal barrier, subtropical species

largely limited by the Cape Hatteras Barrier,
and temperate-endemic (transhatteran) spe-
cies extending both north and south of Cape
Hatteras. Clearly, Cape Cod and Cape Hat-
teras are important geographical and ecologi-
cal barriers to the distribution of many spe-
cies, but the faunal provinces defined by such
barriers alone combine groups of species with
different overall thermal capacities, origins
and histories.

CONCLUSIONS

The molluscan fauna of the inner conti-
nental shelf (= 150 m) of the northwest Atlan-
tic between Cape Hatteras and Labrador con-
sists of three broadly overlapping species
groups which differ in their thermal require-

242 FRANZ AND MERRILL

ments, limits, and adaptive strategies. The
arctic-boreal faunal group, which prevails
north of Newfoundland, is composed almost
entirely of amphiatlantic and North Pacific
species which reach their southern limits on
the American coast near Cape Cod (although
some continue farther south in deeper water).
The boreal faunal group, a mixture of endemic
and amphiatlantic species, overlaps the
arctic-boreal north of Cape Cod. Between
Cape Cod and Cape Hatteras, boreal species
decline in importance, with most reaching
their southern limits on the continental shelf
north of Cape Hatteras. The transhatteran
faunal group consists of species entirely
endemic to the northwest Atlantic, all of which
continue south of Cape Hatteras, and the ma-
jority of which reach their northern limits be-
tween Cape Hatteras and the Gulf of St.
Lawrence.

The ecological and biogeographical homo-
geneity of the arctic-boreal fauna reflects the
Pacific origin of these species via the Arctic
Ocean during the late Pliocene to early Pleis-
tocene. The boreal fauna comprises three
groups of differing origins: Pliocene trans-
arctic migrants; amphiatlantic species with
long histories in the Atlantic; endemic species
derived from American Miocene ancestors.
The latter may have evolved from warm-
temperate progenitors at the time of the de-
velopment of the Labrador Current system (3
m.y. ago). The transhatteran fauna consists of
species conspecific with or derived from
warm-temperate American Miocene species.
Thus, Scarlato's hypothesis, that major bio-
geographic groups reflect thermal conditions
at the time of their origins, is supported in the
above analysis for the arctic-boreal and
transhatteran faunal groups. Their thermal
charcteristics and biogeography on the Amer-
ican coast are correlated with their origins in
space and time. On the other hand, the boreal
group is clearly an artificial aggregation con-
taining species of mixed origins.

The distributions of arctic-boreal species in
the Northwest Atlantic in late glacial times
was probably characterized by severe dislo-
cations and perhaps local extinctions. Trans-
hatteran species tracked appropriate thermal
gradients southward during glacial maxima
and the evidence indicates that suitable con-
ditions for these species continued to exist
south of Cape Hatteras throughout the Pleis-
tocene. Arctic-boreal species survived the
late glacial period in the Northwest Atlantic by
tracking appropriate thermal gradients north-
ward during warmer interglacial periods; and

the reverse during periods of thermal deteri-
oration.

Boreal species on the American coast were
probably forced southward into the zone
bounded approximately by Cape Hatteras
and Cape Cod (35°-42°N) during glacial
maxima. Evidence indicates that environ-
mental conditions in this zone may have been
unsuitable for the continued survival of some
boreal, and especially the more stenotopic
boreo-littoral species. Populations of these
species may have been re-established in the
northwest Atlantic during the PGCO (marine
hypsithermal period) via West Greenland, Ice-
land and northern Europe.

The three faunal groups—because of their
overlapping geographical distributions—are
not completely reconcilable with traditional
zoogeographic constructs for this region. In
particular, the geographical zone between
Cape Hatteras and the Gulf of St. Lawrence, a
zone encompassing two adjacent marine
provinces (Virginian, Nova Scotian) contains
all three faunal groups in varying proportions.
The role of thermal/geographic barriers in
defining biogeographic regions, and in sepa-
rating faunal groups, has been over-empha-
sized in the northwest Atlantic where enor-
mous seasonal thermal fluctuations allow the
co-existence of several distinct faunal groups.

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245

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APPENDIX 1. Arctic-Boreal Gastropods of the northwest Atlantic.

Species

Puncturella noachina (Linné, 1771)
Acmaea testudinalis (Müller, 1776)
Lepeta caeca (Muller, 1776)

Margarites helicinus (Phipps, 1774)
Margarites olivaceus (Brown, 1827)
Margarites costalis (Gould, 1841)
Margarites groenlandicus (Gmelin, 1791)
Solariella obscura (Couthouy, 1838)
Lacuna vincta (Montagu, 1803)

Littorina saxatilis (Olivi, 1792)

Alvania brychia (Verrill, 1884)

Cingula aculeus Gould, 1841
Skeneopsis planorbis (Fabricius, 1780)
Tachyrhynchus erosus (Couthouy, 1838)
Acirsa borealis (Lyell, 1857)

Epitonium greenlandicum (Perry, 1811)
Trichotropis borealis Broderip & Sowerby, 1829
Aporrhais occidentalis Beck, 1836
Velutina velutina (Müller, 1776)

Velutina plicatilis (Muller, 1776)

Velutina undata (Brown, 1839)
Marsenina glabra (Couthouy, 1832)
Lunatia pallida (Broderip & Sowerby, 1829)
Amauropsis islandica (Gmelin, 1791)
Natica clausa Broderip & Sowerby, 1829
Boreotrophon clathratus (Linné, 1758)
Mitrella rosacea (Gould, 1841)
Buccinum glaciale Linné, 1761
Buccinum scalariforme Möller, 1842
Buccinum plectrum Stimpson, 1865
Colus islandicus (Gmelin, 1791)

Colus pubescens (Verrill, 1882)

Colus spitzbergensis (Reeve, 1855)
Volutomitra groenlandica (Moller, 1842)
Admete couthouyi (Jay, 1839)
Propebela turricula (Montagu, 1803)
Propebela pingelii (Môller, 1842)
Oenopota harpularia (Couthouy, 1838)
Oenopota pyramidalis (Strôm, 1788)
Oenopota bicarinata (Couthouy, 1838)
Oenopota decussata (Couthouy, 1839)
Oenopota incisula (Verrill, 1882)

Endemic
northwest Amphi- North Pacific
Atlantic Atlantic Pacific origin!
+ +
+
+ +
+ + +
+ +
+ + +
+
+ ar ?
+ +
—
+
+
+
+ +
+ +
+ + ==
+ + +
+
+ + +
+ + Sh
= + +
+ +
+ = +
4 + +
+ +
+ + ++
+ +
+ AF
+ + +
+ +
+ +
+
+ +
+ +
+ + +
+ + +
+
+ + +
+ + ?
te +
JL
Zu

TFollowing Durham & MacNeil, 1967.

246 FRANZ AND MERRILL

APPENDIX 2. Arctic-Boreal pelecypods of the northwest Atlantic.

Endemic
northwest Amphi- North Pacific
Species Atlantic Atlantic Pacific origin!

Nucula delphinodonta Mighels & Adams, 1842

Nucula tenuis Montagu, 1808

Nuculana pernula (Muller, 1771)

Nuculana minuta (Fabricius, 1776)

Nuculana tenuisulcata (Couthouy, 1838) -
Yoldia amygdales Valenciennes, 1846 u —

Yoldia sapotilla (Gould, 1841) +

Yoldia myalis (Couthouy, 1838) + ?
Megayoldia thraciaeformis Storer, 1838 +

Crenella decussata (Montagu, 1808)

Crenella faba (Muller, 1776) >
Modiolus modiolus (Linné, 1758)

Musculus niger (Gray, 1824)

Musculus discors (Linné, 1767)

Kellia suborbicularis (Montagu, 1803)

Turtonia minuta (Fabricius, 1780)

Astarte elliptica (Brown, 1827)

Astarte montagui (Dillwyn, 1817)

Astarte borealis (Schumacher, 1817)

Serripes groeniandicus (Вгидшеге, 1789)

Clinocardium ciliatum (Fabricius, 1780)

Spisula polynyma (Stimpson, 1860)

Macoma calcarea (Gmelin, 1791)

Liocyma fluctuosa (Gould, 1841)

Mya truncata Linné, 1758

Panomya arctica (Lamarck, 1818)

Lyonsia arenosa Moller, 1842

Pandora glacialis Leach, 1819

Thracia myopsis Moller, 1842

Thracia septentrionalis Jeffreys, 1872 +
Cuspidaria glacialis (G. O. Sars, 1878)

Periploma fragile (Totten, 1835) +

+ + + +
+ +
De)

+++ +
+++ +
+++ ++ + + + + ++++ ++

+++++++

+
+

1Following Durham & MacNeil, 1967.

APPENDIX 3. Boreal gastropods of the northwest Atlantic.

Endemic
northwest Amphi- North Pacific
Species Atlantic Atlantic Pacific origin!

Calliostoma occidentale (Mighels & Adams,
1842)

Lacuna pallidula (da Costa, 1778)

Littorina littorea (Linné, 1758)

Littorina obtusata (Linné, 1758)

Alvania areolata Stimpson, 1851

Hydrobia totteni Morrison, 1954

Omalogyra atomus (Philippi, 1841) +

Bittium alternatum (Say, 1822)

Couthouyella striatula (Couthouy, 1839)

Polinices immaculatus (Totten, 1835)

Lunatia heros (Say, 1822)

+ +
+ + + +

+ + + +

ORIGINS AND DETERMINANTS OF MOLLUSCAN FAUNAL GROUPS 247
APPENDIX 2. (Continued)

Endemic
northwest Amphi- North Pacific

Species Atlantic Atlantic Pacific origin!
Lunatia triseriata (Say, 1826) -
Nucella lapillus (Linné, 1758) + +
Buccinum undatum Linné, 1758 + +
Colus stimpsoni (Mórch, 1867) р
Colus ventricosus (Gray, 1839) +
Colus pygmaeus (Gould, 1841) >
Neptunea lyrata decemcostata (Say, 1836) +
Neptunea despecta (Linné, 1758) +
Propebela elegans (Moller, 1842) + +
Propebela gouldii (Verrill, 1882) ES
Propebela sarsii (Verrill, 1880) u

1Following Durham & MacNeil, 1967.

APPENDIX 4. Boreal pelecypods of the northwest Atlantic.

Endemic
northwest Amphi- North Pacific
Species Atlantic Atlantic Pacific origin!

Nucula atacellana Schenck, 1939 7

Yoldia limatula (Say, 1831) “+ f f

Solemya borealis Totten, 1834 -

Mytilus edulis Linné, 1758 de + 2
Crenella glandula (Totten, 1834) ze

Thyasira flexuosa (Montagu, 1803) + +

Chlamys islandica (Müller, 1776) + ate

Palliolum striatum (Muller, 1776) Ar

Placopecten magellanicus (Gmelin, 1791) +

Anomia squamula Linne, 1758 Ar

Cyclocardia borealis (Conrad, 1831)
Astarte undata Gould, 1841

Astarte castanea (Say, 1822)
Cerastoderma pinnulatum (Conrad, 1831)
Mesodesma arctatum (Conrad, 1830)
Mesodesma deauratum (Turton, 1822)
Siliqua costata Say, 1822

Macoma balthica (Linne, 1758) as + ля
Arctica islandica (Linné, 1767) is

Pitar morrhuanus Linsley, 1848
Mya arenaria Linné, 1758 cf f Sr
Cyrtodaria siliqua (Spengler, 1793)
Zirfaea crispata (Linne, 1758) de 32
Xylophaga atlantica Richards, 1942
Pandora inornata Verrill & Bush, 1898
Pandora gouldiana Dall, 1886
Thracia conradi Couthouy, 1838
Periploma papyratium (Say, 1822)
Periploma leanum (Conrad, 1831)

A eS eA AA aa ——

+++++++

+

+

++++++

Following Durham & MacNeil, 1967.
f = fossil.

248 FRANZ AND MERRILL

APPENDIX 5. Transhatteran mollusks collected on R/V DELAWARE Cruise 60-7, 11-21 May, 1967.

EEE

Gastropoda Bivalvia (Continued)

Stilifer stimpsoni Verrill, 1872
Crucibulum striatum Say, 1824
Crepidula fornicata (Linné, 1758)
Neverita duplicata (Say, 1822)
Natica pusilla Say, 1822

Sinum perspectivum (Say,1831)
Anachis avara (Say, 1822)

Mitrella lunata (Say, 1826)

Busycon carica (Gmelin, 1791)
Busycon canaliculatum (Linné, 1758)
Nassarius vibex (Say, 1822)
llyanassa obsoleta (Say, 1822)
Marginella roscida Redfield, 1860
Kurtziella cerina (Kurtz & Stimpson, 1851)
Cylichnella canaliculata (Say, 1822)
Cylichnella bidentata (Orbigny, 1841)

Bivalvia
Nucula proxima Say, 1822
Nuculana acuta (Conrad, 1831)
Anadara transversa (Say, 1822)
Anadara ovalis (Bruguiere, 1789)
Noetia ponderosa (Say, 1822)
Limopsis sulcata Verrill & Bush, 1898
Aequipecten glyptus (Verrill, 1882)
Aequipecten phrygium (Dall, 1886)
Argopecten gibbus (Linné, 1758)

A EEE

Anomia simplex Orbigny, 1842
Crassostrea virginica (Gmelin, 1791)
Myrtea lens (Verrill £ Smith, 1880)
Lucinoma filosa (Stimpson, 1851)
Divaricella quadrisulcata (Orbigny, 1842)
Thyasira trisinuata Orbigny, 1842

Astarte crenata subaequilatera Sowerby, 1854

Crassinella lunulata (Conrad, 1834)
Dinocardium robustum (Lightfoot, 1786)
Spisula solidissima (Dillwyn, 1817)
Ensis directus Conrad, 1843

Tellina agilis Stimpson, 1857

Tellina versicolor DeKay, 1843

Tellina tenella Verrill, 1874

Macoma tenta (Say, 1834)

Abra lioica (Dall, 1881)

Mercenaria mercenaria (Linné, 1758)
Mercenaria campechiensis (Gmelin, 1791)
Dosinia discus (Reeve, 1850)

Gemma gemma (Totten, 1834)
Petricola pholadiformis (Lamarck, 1818)
Corbula contracta Say, 1822

Corbula swiftiana C. B. Adams, 1852
Barnea truncata (Say, 1822)
Cyrtopleura costata (Linné, 1758)
Pandora gouldiana Dall, 1886

Pandora inflata Boss & Merrill, 1965

MALACOLOGIA, 1980, 19(2): 249-278

A RECONSIDERATION OF SYSTEMATICS IN THE MOLLUSCA
(PHYLOGENY AND HIGHER CLASSIFICATION)

Luitfried v. Salvini-Plawen

Institut für Zoologie, Universität Wien, Wien I, Austria

ABSTRACT

A reconsideration of phylogenetic interrelations in molluscs with respect to several more
recent studies on different groups of various taxa leads to a somewhat revised presentation of
presumed molluscan evolution. Taking into consideration not only the quantitatively predominant
shelled groups, adequately documented as fossils, but allowing also for the minor, yet compara-
tive-anatomically equivalent aplacophoran molluscs, the synorganizationally relevant characters
and organ systems reflect distinct anagenetic pathways. This analysis evidences a homogene-
ous frame of continuous evolution along a phylogenetic main line of archimolluscs—
Placophora—Conchifera, and an early sidebranch of Scutopoda. Four essential steps of prog-
ressive differentiation are obvious which separate a) the Scutopoda (Caudofoveata) from the
Adenopoda (all other molluscs), b) the Solenogastres from the shell-bearing adenopods
(Testaria), c) the Placophora from the Conchifera, and d) the conchiferan groups among each
other; herein, the Placophora and Solenogastres are synapomorphously tied together in contrast
to the merely symplesiomorphous characters in Solenogastres and Caudofoveata (“Арасо-

phora”). A correspondingly modified higher classification is proposed.

INTRODUCTION

Increase in the knowledge of comparative
anatomy and increase in the number of spe-
cies frequently cause systematic problems.
This is especially obvious when a major group
of organisms is thoroughly studied and re-
vised, or when some aberrant organization is
introduced and/or brought to general knowl-
edge. Since systematics should—as far as
possible—coincide with the respective rela-
tionships of different organization with an ade-
quate classification (to get a ‘natural’ system),
all taxa within a group as well as the higher
taxa should be arranged according to equiva-
lent morphological or other quality—but not
with respect to quantity (of species, etc.) or
scientific importances (actual or seeming). In
the endeavour to present phylogenetic rela-
tionships, only monophyletic groups can be
classified together; this, however, can only
seldomly be confirmed within a linear system
(cf. Mayr, 1974). Therefore, a compromise
must be accepted which intervenes between
evidenced phylogenetic course and usable
praxis.

Such systematic discrepancies and prob-
lems have more recently been raised in vari-
ous aspects and levels within the Mollusca,
and especially with regard to differences in
zoological and paleontological points of view.

Most molluscan classifications suffer from
domination by the—generally well-investi-
gated—conchiferan groups, which are some-
times even uniquely regarded as “true” mol-
luscs (cf. Fretter & Graham, 1962, etc.). This
often results also in the proposition to accept
purely conchiferan conditions as ancestral for
molluscan organization: the Conchifera—or
even the mere Gastropoda—are misinter-
preted so as to represent the organizational
standard for all Mollusca (cf. e.g. Yonge,
1947; compare also Runnegar & Pojeta,
1974; Yochelson, 1978). Respective to these
conditions, the present contribution tries to
present and discuss those various discrep-
ancies for the higher taxa within all molluscs,
and to synthesize them for a classification that
is adequate phylogenetically as well as for
practical systematics.

CAUDOFOVEATA AND SOLENOGASTRES

Several more recent studies (S. Hoffman,
1949; Boettger, 1955; Salvini-Plawen, 1969,
1972) have especially dealt with the organiza-
tion of the so-called aplacophoran molluscs,
resulting in the evidence that they constitute
“two long-separate lines” (Stasek, 1972: 40)
which diverged at the basic level of archimol-
luscan organization. When thoroughly com-

(249)

250 SALVINI-PLAWEN

pared in their organ systems, the Caudo-
foveata (the former Chaetodermatina/
Chaetodermomorpha / Chaetodermoidea)
and the Solenogastres (also Neomeniina/
Neomeniomorpha/Neomenioidea) are similar
primarily in the symplesiomorphous mantle
structure and muscle systems, as well as in
the convergently reduced true gonoducts.
The alimentary tract in Caudofoveata could
be derived from the more primitive one in the
Solenogastres (the latter having the most
conservative configuration within all mollusca;
cf. Salvini-Plawen, 1969, 1972, 1979). All
other organ systems (foot, mantle cavity, re-
productive system, also nervous system and
circulatory system), however, are not syn-
organizationally derivable from each other in
both groups, consequently resulting in the
cognition of early convergence of both evolu-
tionary lines.

The Caudofoveata already deviated at the
most primitive level of common molluscan or-
ganization in adapting to a burrowing way of
life. The elaboration of the cerebrally-inner-
vated section of the ventral gliding surface to
the actua! pedal shield, the reduction of the
other gliding surface with the mid-ventral fus-
ion of the laieral mantie rims, and the elabora-
tion of the body wall musculature to a hydrostat-
ic muscular tube are distinct results of that
adaptation. The differentiation of the strong
longitudinal musculature in the anterior body
(including the regression of other muscle sys-
tems) must be understood with respect to the
antagonistic body fluid for burrowing locomo-
tion in the sediment. And the feeding on mi-
croorganisms resulted in a brushing radula of
the distichous type (and later on a forceps-like
seizing organ), as well as in the separation of
a ventral midgut gland including, in higher
members only, the differentiation of a proto-
style and a gastric proto-shield (primitive
stomach; cf. Salvini-Plawen, 1979).

The Solenogastres are conservative mem-
bers of the alternative evolutionary line within
those early molluscs which proceeded in a
gliding-creeping locomotion upon the ventral
surface, but having already differentiated a
peripedal mantle cavity, a rudimentary head
(snout), and the pedal gland. They are still
provided with the primitive mantle cover
and—owing to their early preference for feed-
ing as predators on Cnidaria—with the origi-
nal configuration of a pouched midgut (and
serial dorsoventral muscle bundles). The nar-
rowing of the whole body including the foot,
the partial reduction of the mantle cavity and

its partial internalization are adaptations to a
winding-wriggling manner of muco-ciliary lo-
comotion on secondary hard bottoms (also
coral reefs, littoral, etc.). The manifold modifi-
cations of the monoserial radula and/or the
differentiation of a pharyngeal sucking-pump
are further adaptations for feeding on
Cnidaria (cf. Salvini-Piawen, 1979).

The most obvious evidence for these diver-
gent evolutionary pathways in the Caudo-
foveata and the Solenogastres comes from
the comparative analysis of the pedal system
and the mantle cavity. Solenogastres, Placo-
phora and Conchifera possess a ventrally-
innervated foot and a distinct pedal gland as-
sociated with it; on the contrary, the Caudo-
foveata are only provided with a cerebrally-
innervated pedal shield structurally almost
identical to the foot of other molluscs. The
presence of mucous glandular cells like those
along the pedal groove in the Solenogastres
(cf. S. Hoffman, 1949), the lack of mantle folds
(Fig. 3), and the cerebral innervation of the
pedal shield (Salvini-Plawen, 1972) contradict
its interpretation as secondarily re-estab-
lished pedal organ, but positively indicate its
primitive condition. The ventrally-innervated
section of the ancestral gliding surface in the
caudofoveatan line has been reduced from
posterior to anterior (as is still Obvious in
some species of Scutopus), so that the man-
tle edges are midventrally fused (Fig. 3). The
mantle cavity coincides in its terminal position
with that statement, and it has medially in-
verted pallial grooves with mucous tracts and
with ventrolateral (!) openings of the peri-
cardial outlets (cf. S. Hoffman, 1949; Salvini-
Plawen, 1972). That configuration, as well as
the total lack of further portions of the mantle
cavity essentially serve to contrast the whole
organ system of the Caudofoveata to that in
the Solenogastres (and other molluscs), both
of which cannot be derived from each other.

Also the gonopericardial system of both
Caudofoveata and Solenogastres can in no
case be derived from each other. Findings in
Phyllomenia and further arguments (cf. S.
Hoffman, 1949; Salvini-Plawen, 1970b, 1972,
1978) clearly indicate that the forerunners of
the Solenogastres possessed both pericardio-
ducts as well as gonoducts; the latter, how-
ever, are now predominantly in secondary
connexion by their upper portion with the peri-
cardium (the lower portions then being re-
duced). The pericardioducts open into the
spawning ducts, i.e. the internalized posterior-
lateral sections of the mantle cavity provided

MOLLUSCAN SYSTEMATICS 251

NS

FIG. 1. Comparative arrangement of the pallio-pericardial system in A Placophora-Lepidopleuridae, B
Solenogastres, and С female Caudofoveata (after Salvini-Plawen, 1972). Ct ctenidium, Cu mantle-cuticle,
Ed hind gut, Fd sole glands, Lg spawning duct, Mf foot, MI longitudinal muscle, NS//NSv/NSlv lateral and
ventral nerve cords, Pc pericardial cavity, Pd pericardioduct, Sr mucous tract.

with the mucous tracts (S. Hoffman, 1949; cf.
Fig. 1). In contrast, the pericardioducts in the
Caudofoveata open into ectodermal glandular
ducts (cf. Fig. 1) which, owing to their configu-
ration as well as to their structure, neither be-
long to the pericardioducts nor to the mantle
Cavity (into which they open ventrolaterally by
means of a narrow opening with strong
sphincter). Since there are no real gonoducts
in the Caudofoveata, these glandular ducts
may possibly constitute the altered lower por-
tions of the original gonoducts (cf. Salvini-
Plawen, 1972: 251 ff.).

Such outlined conditions, and properties in
further organ systems synorganizationally
considered in Caudofoveata and in Soleno-

gastres (cf. Salvini-Plawen, 1972; Salvini-
Plawen & Boss, 1980), cannot be derived
from each other and hence obligatorily prove
the basically independent evolutionary differ-
entiation of both groups from an ancestral or-
ganization common to all molluscs (see Figs.
3-5).

Following knowledge of the “арпуейс
Aplacophora” (Stasek, 1972: 19),1 the
Caudofoveata (Boettger, 1955) have been
separated from the solenogastrid aplaco-
phorans and raised to the rank of an inde-
pendent class, equivalent to Solenogastres
and Placophora (Salvini-Plawen, 1967,
1968b, 1975). The some 65 described spe-
cies are grouped in three families (Salvini-

TAlthough Stasek (1972: 19 & 40) is well aware of the “long-separate,” “diphyletic” aplacophoran molluscs, he takes this
knowledge not into account and inexplicably classifies both groups again under one single taxon. There are no comments
here on the mis-conceived interpretation by Scheltema (1978) as concerns commonly inherited (symplesiomorphous) and

phylogenetically specialized (apomorphous) characters.

292 SALVINI-PLAWEN

7%

a Ô
О

à

À Ye
D

N HP OPA
A /

<

Sans

a —

|
ER KR

= $27
= Dos y
Shy ae
qa
E D

FIG. 2. Differentiation of the mantle cover in just metamorphosed individuals of Nematomenia banyulensis
(Solenogastres; A lateral, B dorsal view) and of Middendorffia caprearum (Placophora; C and D two succes-
sive stages) (after Pruvot and Kowalevsky from Salvini-Plawen, 1972). PI shell plates in formation through
coalescence of the juxtaposed scaly bodies Sp arranged in seven transverse rows.

Plawen, 1968b, 1975) within the single order
Chaetodermatida Simrotn (emended by
Smith, 1960).

Precisely defined by the term Soleno-
gastres (Gegenbaur, 1878: 139; solen =
tube, groove, and gaster = venter, belly),
these numerically predominant aplacophoran
organisms with a ventrally-innervated foot
narrowed to a groove persist as a distinct
class; the unfamiliar terms Telobranchiata
(Koren & Danielssen, 1877) and Ventroplicida
(Boettger, 1955) hence can be disregarded. A
comprehensive analysis of the 180 Recent
species (Salvini-Plawen, 1978) brought about
the establishment of four orders (Pholi-
doskepia, Neomeniomorpha, Sterrofustia,
and Cavibelonia) within two higher levels of
organization (supraorders Aplotegmentaria
and Pachytegmentaria).

The long ignored investigation of aplaco-
phoran molluscs, their seemingly small num-
bers, their lack of a shell, and their worm-like
shape unfortunately led to a misunderstood
interpretation until a few years ago in regard-
ing them either as vaguely mollusk-like or as
aberrant Mollusca. Only a few authorities (e.g.
H. Hoffmann, C. R. Boettger), according to
their general knowledge, took a neutral point
of view independent of hypertrophic informa-
tion on Conchifera and evaluated the mol-
luscan organizations comparatively according
to differentiated quality. As a consequence of
the more recent organizational-evolutionary
elucidations, neither the superficially similar
appearance of Caudofoveata and Soleno-

gastres, пог their seemingly hidden manner of
living in being exclusively distributed in marine
habitats of greater depths can serve as argu-
ments for conservative under-estimation: The
taxon Aplacophora (Ihering, 1876) had to be
abandoned, since it artificially unites two basi-
cally different, diphyletic evolutionary lines
which merely coincide by some ancestral
(symplesiomorphous) characters but by no
single commoniy-acquired (synapomorphous)
nroparty.

PLACOPHORA

In considering the (Poly-)Placophora, one
condition has generally not been taken suf-
ficiently into account, viz. the ontogenetic dif-
ferentiation of initially only seven shell plates
(cf. summary in Smith, 1966). That peculiarity
is underlined by the predominant ‘abnormal-
ity’ in adults, i.e. the formation of only seven
plates (cf. H. Hoffmann, 1929/30: 173; Taki,
1932). A further particularity is met within the
Solenogastres, where the metamorphosed
stage of Nematomenia banyulensis (a mem-
ber of the most conservative Pholidoskepia) is
provided dorsally with seven transverse rows
of juxtaposed scaly bodies; this coincides ex-
actly with an occasional condition in the
Placophora (Fig. 2), where the formation of the
plates results from the coalescence of cal-
careous granulations arranged in seven
transverse rows.2 Finally, the record of fossil
Placophora with seven plates, described as

2formation des plaques par la coalescence de granulations calcaires” (Kowalevsky, 1883: 33).

MOLLUSCAN SYSTEMATICS 253

Septemchiton (Bergenhayn, 1955; Sanders,
1964), must be emphasized. This seven-
plated condition shows that the placophoran
stock originated in organisms which differen-
tiated only seven primordial calcareous
plates, presumably through coalescence of
the formative anlagen (the isolated-intracellu-
lar centers of calcification) of juxtaposing
bodies provided with a basal quinone-tanned
organic layer (“сир”; cf. $. Hoffman, 1949;
Beedham & Trueman, 1967, 1968; Carter &
Aller, 1975); the same stock also gave rise to
the Solenogastres. The Septemchitonida,
therefore, are either the direct successors of
that primitive stock, or they form an evolution-
ary line arising by paedomorphy. In either
case, however, it appears necessary to sepa-
rate the order Septemchitonida within a spe-
cial subclass, for which the term Heptaplacota
is proposed.

The comprehensive revision of the Placo-
phora by Bergenhayn, (1930, 1955, 1960) in-
cluded fossil as well as Recent members and
resulted in a homogeneous system that is
largely accepted (cf. Smith, 1960, Van Belle,
1975). With the separation of the Septem-
chitonida as a special subclass Heptaplacota,
the main line constitutes the (hypothetical)
Eoplacophora (Pilsbry, 1893; see Bergen-
hayn, 1955: 39), more or less identical with
the subclass Loricata including Bergenhayn’s
orders Chelodida, Lepidopleurida, Ischno-
chitonida (= Chitonida), Acanthochitonida,
and Afossochitonida3). Only the Chelodida
are hence included with the supraorder
Palaeoloricata and contrasted to the other
orders = Neoloricata; the latter, however, do
not form a monophyletic group but have, ac-
cording to Bergenhayn (1960: 176), a di-
phyletic root within the Chelodida. The Neo-
loricata constitute therefore an artificial group
to be avoided. Starobogatov & Sirenko (1975)
discuss in a short article the classification
within the Neoloricata and reclassify them in
accepting the articulamentum-bearing orders
Scanochitonida nov., Lepidopleurida includ-
ing Bergenhayn's Afossochitonidae, and
Chitonida including Ischnochitonina and
Acanthochitonina; the dubious Llandeilo-
chiton is omitted (cf. also Van Belle, 1975),
and the Palaeoloricata anyway remain identi-
cal with the order Chelodida.

The first term given for the chitons as an
independent group was that of Ducrotay-
Blainville in 1819 as Polyplaxiphora; it was

amended in 1821 to Polyplacophora by Gray.
It was, however, Ihering, (1876) who intro-
duced the group in a comparative point of
view with respect to the molluscs; accordingly
his—also familiar, and even simpler—term
Placophora may be preferred, even more so
since there is no problem in confusing the
group.

TRYBLIDIIDA AND BELLEROPHONTIDA:
GALEROCONCHA

Early Cambrian univalve molluscs have
long been a cause for scientific debate wheth-
er planispiral shells belong to untorted (exo-
gastric) or torted (endogastric-gastropod) or-
ganization (cf. Runnegar & Jell, 1976; Berg-
Madsen & Peel, 1978). Recent investigations
(Rollins & Batten, 1968, and others) have
shown that the exogastric tryblidiids already
possessed a marked shell sinus, since
Sinuitopsis acutilira (Hall) with its three pairs
of symmetrical muscle scars, as well as other
similarly organized species unequivocally
must be regarded as untorted-exogastric. The
sinus in Sinuitopsis therefore proves that this
shell character (and even the shell slit) has
been evolved adaptively long before gastro-
pod torsion took place. Thus there is no further
argument in favour of considering the Beller-
ophontida, provided with a sinus and/or shell-
slit and with one symmetrically-arranged pair
of dorsoventral muscle bundles (cf. Knight,
1947), as belonging to the gastropods; the
sinus or slit merely demonstrates the sym-
metrical (paired) arrangement of the pallial
organs (cf. also Fretter, 1969).

Pojeta & Runnegar (1976: 24 ff.) likewise
discuss most arguments and come to the con-
clusion that the Bellerophontida as well as the
Helcionellacea were untorted organisms with
an exogastric shell (cf. also Runnegar & Jell,
1976). The symmetrical arrangement of one
single pair of muscle scars in adults, however,
might also be due to regulative migrations of
the muscles during larval development (com-
pare Scissurellidae, and cf. Crofts, 1937,
1955); but additional conditions refute the
arguments of Knight (1947, 1952); Cox &
Knight, (1960); Berg-Madsen & Peel (1978);
and also Stasek (1972):

a) Gastropod torsion occurs in two phases,
and loss of equilibrium in the pelagic larva
after the first phase because of the heavier

3The suffix -ina generally designates a suborder, whereas for orders the ending -ida should be used (cf. also Starobogatov &

Sirenko, 1975).

254

main bulk of the visceral mass at the left side
automatically causes an asymmetry of the
whole pallio-visceral complex of the larva in-
cluding the covering shell: only the left set of
pallial organs develops (cf. Fretter, 1969) and
the shell becomes asymmetrical before (!) the
second phase of torsion begins (cf. Crofts,
1937: 242 f, 259). Since that asymmetrical
growth is independent of the (endogastric)
coiling of the visceral hump, every shell of
torted animals principally demonstrates an
asymmetrical condition in the larvae (cf.
Fretter & Graham, 1962: 447); this however,
is not the case within the Bellerophontida.

b) The growth of a more coiled shell in the
plantigrade stage of metamorphosing аг-
chaeogastropods with differential regulative
processes causes a posterior overweight
(right side of the post-torsional visceral hump
with shell) which is compensated by dextral
helicoid growth and thus appears to be an
indirectly-caused consequence of torsion.
Planispiral coiling can therefore generally be
considered as proof of an untorted condition
(comp. also most Nautiloida, Ammonoida,
etc.); only rarely is symmetry secondarily
reached, e.g. in some exceptional gastropods
such as Caecum, several Omalogyridae, and
others.4)

c) Many operculum-bearing gastropods
show some very distinct adaptive structures at
the shell-aperture in relation to the respective
operculum—in contrast to all known Beller-
ophontida with a more or less symmetrical,
homogeneously formed and wholly regular,
wide holostornous aperture. This coincides
with the negative record of opercula in beller-
ophontid beds, indicating that the operculum is
obviously an evolutionary attribute of the
torted condition, the more since its functional
secretion takes place asymmetrically (!) by
glands at the post-torsional right side of the
posterior pedal ectoderm (compare also
Crofts, 1937: 240; 1955: 738).

Summing up earlier arguments (cf. Pojeta &
Runnegar, 1976) and the above presented
additional arguments, we may positively state
that the majority of organisms assigned to the
Bellerophontida were untorted animals with a
planispiral, exogastric shell. Consequently
they have to be separated from the torted
Gastropoda and classified closer to the cup-

SALVINI-PLAWEN

shaped tryblidiids, as already realized by
Simroth (1904) and Wenz (1940) and as also
discussed by Salvini-Plawen (1972: 272 f).
Wenz classified the Tryblidiacea and Beller-
ophontacea together within the subclass
Amphigastropoda, but without separation
from the gastropods (the diagnostic definition
of the latter, therefore, becoming inaccurate).
Today there is no doubt that the Gastropoda
are defined by torsion (and presence of an
operculum), and that the untorted groups
have to be arranged as a distinct class out-
side the gastropods. Hence, the term Galero-
concha may be suitable to include Tryblidiida
and Bellerophontida, since ‘Monoplacophora’
is (aS a synonym) unequivocally tied to the
cap-shaped ог orthoconic Tryblidiida
(= Tryblidiacea Wenz)> and contrasted to the
Bellerophontida (= Bellerophontacea Wenz).
The class Galeroconcha is defined to consist
of fossil and Recent laterally-symmetrical and
untorted Conchifera with a cap-shaped to
(exogastrically) planispiral shell, devoid of a
siphon and covering the whole body, and with
symmetrically-paired dorsoventral muscle
bundles which may be fused; it includes the
two orders (subclasses) Tryblidiida (Mono-
placophora) and Bellerophontida (Beller-
omorpha) (cf. Salvini-Plawen, 1972: 272).
Findings of Recent tryblidiids (Neopilina)
have led not only to a reactivation of the an-
nelid-theory (derivation of the molluscs from
segmented coelomates) which has since
been totally refuted by Boettger (1959),
Vagvolgyi (1967), Salvini-Plawen (1968a,
1969, 1972), Stas ek (1972), Trueman (1976)
and others; it also resulted in an increased
interest in the whole group, followed, how-
ever, by some taxonomic confusion and no-
menclatorial misinterpretation (cf. Cesari &
Guidastri, 1976; Berg-Madsen & Peel, 1978;
Yochelson, 1978). On the one hand, there is a
peculiar misuse of the taxon and term Mono-
placophora (by Runnegar & Jell, 1976, even
assigned to Knight, 1952); most obvious,
however, is the trend toward a hypertrophical
Classification of the fossil genera and families
(cf. Knight & Yochelson, 1958; Starobogatov,
1970; Golikov & Starobogatov, 1975, and
others) which does not correspond to the de-
gree of morphological differences that are
present. Similarly, neither the classification of

4The protoconchae in Tryblidiina are mostly bulbous and uncoiled (cf. Menzies, 1968: 7); the slight larval (pretorsional-)
dextral coiling in Neopilina galatheae therefore has nothing to do with the helicoid coiling in plantigrade (postlarval) gastropods.

5“man könne die Tryblidiacea geradezu als Monoplacophora bezeichnen” (Wenz, 1940: 5, citing Odhner); compare also

Yochelson, 1978.

MOLLUSCAN SYSTEMATICS 255

TABLE 1. Classification of the Galeroconcha.

Classis GALEROCONCHA nov. (pro “Amphigastropoda” Simroth in Wenz, 1940)

Ordo Tryblidiida Wenz, 1938 (= Monoplacophora Odhner in Wenz, 1940)
Subordo Tryblidiina Pilsbry, 1899
Subordo Cyrtonellina Knight & Yochelson, 1958
Subordo Archinacellina Knight, 1956

Ordo

Bellerophontida Ulrich & Scofield, 1897 (= Belleromorpha Naef, 1911)

Subordo Sinuitopsina Starobogatov, 1970
Subordo Helcionellina Wenz, 1938
Subordo Bellerophontina McCoy, 1851

some more closely related genera or families
in orders, nor a subdivision of the newly de-
fined class Galeroconcha into two subclasses
appears to be adequate and hence justified;
as evidenced by Yochelson (1967), Pojeta &
Runnegar (1976), Runnegar & Jell (1976), or
Berg-Madsen & Peel (1978), the morphologi-
cal variation does not exceed the level of two
orders.

With the new concept of Galeroconcha, the
classification of Horny (1965) can also be
abandoned: his Tergomya are identical with
the Tryblidiina (see Table 1), and his
Cyclomya are partly incorporated within the
Bellerophontida (cf. also Pojeta & Runnegar,
1976; Runnegar & Jell, 1976). To avoid fur-
ther confusion, we retain the general outline
of both orders as presented by Knight &
Yochelson (1960), Yochelson (1967), and
Berg-Madsen & Peel (1978), which is pre-
dominantly based upon the configuration of
the concha. Some uncertainty remains only
with a few cyrtoconic members, and the posi-
tion of the Archinacellina as well as Helcionel-
lina still needs confirmation (cf. Knight &
Yochelson, 1960; Yochelson et al. 1973;
Golikov & Starobogatov, 1975; Pojeta &
Runnegar, 1976; Yochelson, 1978); the Multi-
fariida Byalyi can be recognized as a separate
family within the Sinuitopsina, and the
Kirengellida Rozov obviously belong to the
Tryblidiina close to Scenella (cf. Runnegar &
Jell, 1976; Berg-Madsen & Peel, 1978).

The classification of the Galeroconcha, in-
cluding the Tryblidiida (with cap-shaped to
cyrtoconic concha, mantle cavity generally
peripedal) and the Bellerophontida (with exo-
gastrically-planispiral concha generally pro-
vided with a midposterior sinus or slit, mantle
Cavity generally confined to the posterior
body), can be summarized as in Table 1.

Finally, it should be pointed out that despite
agreement with Runnegar in considering the
Bellerophontida to be untorted organisms and
hence with an exogastric visceral sac, there is

disagreement in two major phylogenetic
points of view. First, as extensively demon-
strated by Salvini-Plawen (1972), nowhere
discussed by Runnegar, the ontogenetic as
well aS comparative-anatomical condition in
the Placophora unequivocally evidences their
interconnecting organizational level between
the aplacophoran and conchiferan grades
(compare also Figs. 3-5). Therefore, the hy-
pothesis of a secondary subdivision of the
concha as evolving to seven or eight plates in
Placophora (Runnegar & Pojeta, 1974; Pojeta
& Runnegar, 1976) has to be rejected. More-
over, the cap-shelled (limpet-shaped)
Tryblidiina must be considered ancestral to
the other conchiferans. This is supported by
further arguments concerning the compara-
tive analysis of Placophora and Neopilina (cf.
Salvini-Plawen, 1969; 1972). Consequently,
the tergomyan Tryblidiina are the primitive
stock when compared with other Galero-
concha. Secondly, the functional synorgani-
zation of comparative anatomy confirm the
evolutively close relationship between the
Bellerophontina and the origin of Gastropoda
as presented below. Consequently, there is
full agreement with the critique of Berg-
Madsen & Peel (1978: 123) as concerns the
phylogenetical role of Pelagiellacea empha-
sized by Runnegar.

GASTROPODA

The principal diagnostic criterion for the
Gastropoda is torsion (cf. also Yochelson,
1967, and others), supplemented by the
presence of an operculum and the lack of the
(post-torsional) left gonad. According to the
arguments discussed above, the Bellero-
phontida are not considered to be torted and
are thus separated from the gastropods.
There is, however, distinct evidence that—in
contrast to Runnegar & Jell (1976) or Runne-
gar & Pojeta (1974)—some Bellerophontina

256 SALVINI-PLAWEN

MOLLUSCAN SYSTEMATICS 257

ЭТРНОМОРОТ

lor

mantle and concha
laterally enlarged;
N anglionate

CAUDOFOVEATA

body iform;

with m Rinses
paired trolateral

neury with terminal s
and two auricles; se

FIG. 4. Anagenetic relations of the molluscan classes by means of commonly-acquired (synapomorphous)
main features indicated for the levels (encircled).

Bae
FIG. 3. Scheme of the evolutionary pathways in Mollusca (predominantly with respect to the mantle, the
mantle cavity, the locomotory surface, the dorsoventral as well as longitudinal muscle systems, and in A, Bj,
C the main nervous system). A ancestral Mollusca; B Adenopoda; C Scutopoda (Caudofoveata). | ancestral
Adenopoda; Il ancestral Heterotecta; Ш Solenogastres; IV Placophora; V ancestral Conchifera; VI Galero-
concha (Neopilina); VII Bivalvia; VIII Siphonopoda (Nautilus); IX Gastropoda (Haliotis); X Scaphopoda. 1
inner fold of mantle edge (= mr), 2 middle fold of mantle edge, 3 outer fold of mantle edge; ce cuticularized
cilia-epithelium of mantle cavity, co concha, ct ctenidium, dg midgut gland, fc cerebrally innervated section
of locomotory surface (in C: pedal shield), fv ventrally innervated section of locomotory surface (in B: foot), /
intestine, /s juxtaposed scaly calcareous bodies, ma scales- and cuticle-bearing mantle, mc mantle cavity,
mg midgut, m/ musculus longitudinalis, mic musculus (long.) circularis, mr mantle rim (= 7), mt mucous tract,
p periostracal groove, pg pedal gland, re rectum, sg sole glands, so terminal sense organ, sp shell plate.

SALVINI-PLAWEN

258

SCUTOPODA

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MOLLUSCAN SYSTEMATICS 259

were direct phylogenetic and morphological
forerunners of the Gastropoda, initially merely
separated by the shift of the pallio-visceral
complex into an anterior position.

This process of torsion proper was probably
not due to a spontaneous mutation (cf. Crofts,
1955; Fretter & Graham, 1962) which would
demand the postulation that at least two re-
producing individuals simultaneously under-
went an identical and dominant mutation to be
spread in the population; with respect to the
condition in lower gastropods, it was much
more probably because of two different grad-
ual adaptive processes, (a) to regulate stabili-
zation of the larval equilibrium and (b) to regu-
late balancing posture in the plantigrade
stage (cf. Crofts, 1955: figs. 9-10; Ghiselin,
1966: 347; Minichev & Starobogatov, 1972;
Underwood, 1972). Larvae of exogastrically
coiled animals (but not of cap-shaped trybli-
diids as speculated by Stasek, 1972) show
already in early stages a prominent visceral
mass with the shell rudiment; it thus disturbs
the axial equilibrium as well as the balance in
the case of directional swimming. That effect
is row ontogenetically compensated by
the reestablishment of equilibrium relative to
the direction of the larva’s movement carried
out by the developmental acceleration of the
right larval shell muscle running obliquely to
the head-foot: its contraction causes the first
(and true) phase of torsion (90°) in relation
to the foot (but not in relation to the axis of
equilibrium), swinging the visceral mass into
the right position for the larva’s balancing
posture in the pelagic zone relative to the
propelling ciliary apparatus. The genetic fixa-
tion of such a precocious acceleration
(tachymorphous heterochrony) for larval equi-

ЕЕ

librium consolidated torsion of 90°; it directly
resulted in the mere development of the (post-
torsional) left set of pallial organs including
the retractor (cf. Fretter, 1969), since the
respiratory water currents enter (left-) frontally
and leave toward the (frontal) right.

That quasi-monotocardian condition is not
altered before the beginning plantigrade
stage of the metamorphosing larva, in which
the balancing posture relative to the substra-
tum and the axial divergence of about 90°
(palliovisceral bulk versus body axis) is regu-
lated by differential growth processes—shift-
ing the mantle cavity into rather an anterior
position (second phase of approximately an-
other 90°; cf. Crofts, 1937, 1955). The mantle/
shell sinus or slit already existing appears to
be a prerequisite for the survival of such
torted animals in not shedding their waste
products towards the inhalant currents. The
regulative growth also includes the develop-
ment of the right pallial organs and right dor-
soventral retractor muscle.

The process of torsion and its conse-
quences may herewith be summarized as:

—The pretorsional presence of a planispirally
coiled visceral hump with a midposterior
shell-sinus or slit (compare Bellero-
phontina);

—regulative shifting of the heavy visceral
mass of the larvae towards an arrangement
of equilibrium for their balancing posture in
the pelagic environment, and the adaptive
dominant development of the right larval,
dorsoventral retractor muscle;

—positively selective, genetic stabilization of
the precociously accelerated development

FIG. 5. Diagram of the phylogenetic radiation of the Mollusca (black bars indicate fossil records; time-scale in
millions of years, logarithmic). (1) Hypothetical archi-mollusc (main organization, and ventral view) with
overall ventral gliding surface (black), posterio-lateral mantle cavity, scale-bearing mantle, straight midgut
pouched laterally, serial dorsoventral muscle bundles, gonopericardial system, and main nervous system
with terminal sense organ(s). (2) Evolutionary branch of burrowing Scutopoda (lateral and ventral) with
cerebrally-innervated section of locomotory surface (= pedal shield, black) and reduction of its ventrally-
innervated section. (3) Evolutionary branch of gliding-creeping Adenopoda (lateral and ventral) with
ventraily-innervated section of locomotory surface (= foot, black) including the pedal gland, with rudiment of
head, and with peripedal-preoral mantle cavity. (4) Level of primitive Heterotecta (dorsal view), dorsal mantle
with seven transverse rows of juxtaposed scaly bodies. (5) Level of Solenogastres (ventral and dorsal) with
narrowed body and foot, mantle cavity reduced to preoral sensory pit (atrial sense organ) and to internal
tubes (Spawning ducts); adult mantle cover altered again to homogeneous arrangement of scales. (6) Level
of early Placophora (= Heptaplacota; dorsal view) with consolidation of juxtaposed scaly bodies to seven
shell plates. (7) Regressive dorsoventral musculature in Caudofoveata. (8) Serial arrangement of dorso-
ventral musculature in Solenogastres; compare (1). (9) Serial arrangement of dorsoventral musculature in
recent Placophora, concentrated according to the eight shell plates (8 x 2 = 16). (10) Primitive Conchifera
with further concentration of the placophoran dorsoventral musculature (9) according to the homogeneous
concha (see Neopilina).

260 SALVINI-PLAWEN

of that right larval retractor: establishment
of the first phase of torsion (90°);

—the predominant development of the pre-
torsional right (or: the retarded develop-
ment of the pretorsional left) pallial organs
due to respiratory currents (quasi-monoto-
cardian stage);

—regulation of the divergent axial and bal-
ance conditions between the visceral hump
and the head-foot respective to plantigrade
movement by differential growth processes
in metamorphosing animals: second phase
of torsion® of approximately another 90°;
this regulation includes and is combined
with

—the development of the second (posttor-
sional right) set of pallial organs including
the retractor muscle, the mantle/shell
sinus/slit enabling the now paired inhalant
respiratory current to be directed symmetri-
cally from the latero-frontal areas towards
the anterio-medio-dorsal area.

Starting from such a possible torsion pro-
cess of two different adaptive phases which
fully corresponds to the developmental pat-
terns, Recent gastropods appear to belong to
different lines having achieved pallial asym-
metry independently (water currents, ctenidia,
etc.):

1) The most conservative stock—also with
respect to shell structure (cf. MacClintock,
1967)—possesses paired pallial organs
(Zeugobranchia) and paired dorsoventral
retractor bundles in the adults: Scissurel-
lidae, Fissurellidae, Haliotidae;

2) The predominance of the posttorsional
right retractor muscle and helicoid coiling
result in the loss of the left retractor mus-
cle: Pleurotomariidae;

3) The hypertrophy of the right retractor mus-
cle and helicoid coiling leads to the sup-
pression of the left retractor as well as to
the right set of pallial organs: Trochacea;

4) The reason for the change in water cur-
rents and the abandonment of the right set
of pallial organs remains enigmatic (cf.
Yonge, 1947: 493, Golikov & Staroboga-
tov, 1975: 190 f), since both retractor mus-
cles are obviously retained and are united
posteriorly (cf. Smith, 1935: 122 & fig. 25
with Crofts, 1955: 730 & fig. 19; but com-
pare also Dodd, 1957): Patellacea;

5) The hypertrophy of the (posttorsional) right

excretory-genital duct causes the pro-
nounced asymmetry with the loss of the
right set of pallial organs: Neritacea
(paired retractor muscles retained);

6) The asymmetry of the pallial organs is due
to a paedomorphous retention of the larval
asymmetry (first phase of torsion, 90°)
prior to regulation in the plantigrade stage.
Owing to a long-lasting, planktotrophic
larval life, the development of the right pal-
lial organs as well as of the right retractor
was more and more retarded; the period of
formative potency to regulate the sym-
metry of the pallial organs was missed and
the potency finally lost, so that the larval
‘quasi-monotocardian condition was
preserved also in the post-metamorphic
stage: Monotocardia, Pulmonata, Gymno-
morpha, Opisthobranchia. The second
phase of torsion during the early planti-
grade stage thus merely comprises the dif-
ferential growth to regulate the condition of
balance and axes, but not the symmetriza-
tion of the pallial organs; occasional ata-
vistic conditions may occur (e.g. paired re-
tractor muscles in Rissoella, Lamellaria,
Trivia, Velutina, or the larvae of Acteon; cf.
Fretter & Graham, 1962; Bebbington &
Thompson, 1968).

Among these lines with differently caused
asymmetry, in accordance with other char-
acters (cf. Yonge, 1947; Cox, 1960a) the
groups (1) and (2) form one branch, as do the
more advanced Trochacea (3); all three lines,
however, are characterized by the predomi-
nance of the (posttorsional) right retractor
muscle, and they retain the right excretory or-
gan. The latter character is also maintained in
the Patellacea (4) which, however, have a
special organization, combining certain con-
servative traits with advanced ones, unlike
other archaeogastropods (cf. Golikov &
Starobogatov, 1975): Thus the odontophore
and the complexity of the radula musculature
may be a conservative character (cf. Graham,
1964: 326; 1973: 343), as the ctenidium ap-
pears to be; in contrast, the rudimental coiling
of the shell without sinus or slit together with
other characters point to an advanced level,
at least adaptively removed from the common
origin as far as the Trochacea are concerned,
but with special properties.—On the other
hand, the Neritacea (5) as well as all other

би must be pointed out that neither this second phase nor the detorsion in Opisthobranchia and Gymnomorpha are true
rotation processes, but are due to regulative growth processes (cf. also Brace, 1977).

MOLLUSCAN SYSTEMATICS 261

(monophyletic ?) gastropods (6) show the left
excretory organ retained; in the Monoto-
cardia, etc., the loss of the right set, however,
obviously is due to an inhibitory discontinua-
tion during development (abandonment of the
regulative symmetrization in the pallial or-
gans), whereas in the Neritacea a special
condition of the reproductive system shows
quite different evolutionary pathways.
Additionally, both the Neritacea and Patel-
lacea are characterized by a conservative
morphology of their ctenidium: In contrast to
Yonge (1947: 495 ff) we cannot regard these
organs as derived from a condition almost
identical to that in zeugobranch gastropods.
The merely basal attachment of the ctenid-
ium, its lack of skeletal rods, as well as its
short and stoutish lamellae, these characters
rather prove a primitive, i.e. conservatively re-
tained condition when compared with the
ctenidia in Caudofoveata, Placophora, and
also Neopilina; the same holds good even for
the Valvatacea. Thus, also in this respect,
both groups appear to be early offshots from
the common gastropod stock, not yet having
undergone in their ctenidia those alternations
typical for the main lines (the skeletal rods, for
example, are supports for mechanical needs,
being analogous not only to those in Siphon-
opoda = Cephalopoda but also in Bivalvia).
Summing up the evolutionary pathways
within early gastropods (cf. also Cox, 1960а;
Golikov & Starobogatov, 1975), there appear
to exist two main lines (1-3) and (6), as well
as two early side-branches (4) and (5). In ac-
cordance with Yonge (1947) and Golikov &
Starobogatov (1975), respectively, both the
latter groups have to be admitted a more sep-
arate status? within the Archaeogastropoda.
Hence, the order Archaeogastropoda would
be classified adequately in three suborders,
viz. the Vetigastropoda (nov.), the Doco-
glossa = Patellina, and the Neritopsina; the
new taxon Vetigastropoda (no former term
available) is defined by the dominant pres-
ence of the (posttorsional) right dorsoventral
retractor muscle as well as the right excretory
organ and by bilamellate ctenidia with skeletal
rods, and it includes the Macluritoidea,
Pleurotomarioidea, Cocculinoidea, Trochoi-
dea, and Murchisonioidea (7?) (cf. Cox, 1960;
Cox & Knight, 1960). Despite the emphasis of

Golikov & Starobogatov (1975), the other
gastropods (line 6 above)—even if possibly
polyphyletic—might better be classified in
Caenogastropoda (including Mesogastro-
poda and Neogastropoda), Pulmonata, Gym-
nomorpha, and Opisthobranchia.

As is generally accepted and repeatedly
evidenced by developmental patterns, the
groups of Opisthobranchia underwent con-
vergent, gradual so-called detorsion, thus
secondarily regaining euthyneury in different
degrees by regulative differential growth (cf.
Brace, 1977). This is, however, not the case
in the still “prosobranch” Pulmonata, the so-
called euthyneury of which results from the
extreme concentration of the nervous system.
Hence, the Euthyneura are not a monophy-
letic group (cf. also Minichev, 1972) and the
pair of taxa Streptoneura/Euthyneura should
be dropped. Within the Pulmonata, in contrast
to earlier opinion (cf. Boettger, 1954), there
are three orders to be recognized (Archaeo-
pulmonata, Basommatophora, Stylommato-
phora). As accurately elaborated by Morton
(1955) and Van Mol (1967), the Ellobiidae
and Otinidae have to be separated as a spe-
cial group, the basic Archaeopulmonata; that
classification has already been accepted in
the textbook by Gótting (1974).

The Opisthobranchia, the monophyly of
which—rooted in early, sediment-ploughing
cepnalaspideans (cf. Brace, 1977)—is be-
coming more and more weakened (cf.
Robertson, 1974), are variously classified in
five to nine or even more orders (cf. Morton,
1963, etc.), an arrangement in seven orders
stands—according to recent knowledge—
critical estimation: 1) The Pyramidellimorpha.
2) The Cephalaspidea, divided into the main
group Bullomorpha and into the Thecosomata
as suborders (cf. Boettger, 1954); herein the
Philinoglossoidea and Acochlidioidea simply
constitute two differently evolved bullo-
morphan family groups (but no separate sub-
orders or even orders; cf. Salvini-Plawen,
1973b). 3) The Anaspidea, divided into
Aplysiomorpha and Gymnosomata (sub-
orders). 4) The Saccoglossa (Sacoglossa
emend., Ascoglossa, Monostichoglossa). 5)
The Notaspidea. 6) The Nudibranchia, con-

7The separation of the Neritacea as an order distinct from the Archaeogastropoda appears not to be justified (as done by
Yonge, 1947; Morton & Yonge, 1964; Franc, 1968), nor is the arrangement of the Patellacea as Cyclobranchia in contrast to
Scutobranchia and Pectinibranchia (as done by Golikov & Starobogatov, 1975). Moreover, there is no organizational
justification to hypertrophize the taxonomic rank of more or less constant family groups (as do Cox & Knight, 1960 or

Golikov & Starobogatov, 1975).

262 SALVINI-PLAWEN

fined to the suborders Dendronotina, Armin-
ina, and Aeolidiina. 7) The Anthobranchia
(= Doridacea) which are comparative-
anatomically well-separated from the former
group(s) (cf. Ghiselin, 1965; Minichev, 1970;
Brace, 19772151);

The systematically greatly contested, shell-
less Onchidiacea and Soleolifera (Veronicel-
lacea) doubtlessly constitute a natural rela-
tionship (cf. H. Hoffmann, 1925; Van Mol,
1967). The more conservative Onchidiidae
still retain a modified pallial cavity (the
“cloaca”), and the so-called lung-cavity clearly
represents an additional, new formation, not
derivable from tissues of the pallial cavity (cf.
Fretter, 1943, also H. Hoffmann, 1925: 324-
326). Other characters ostensibly identical to
those in Pulmonata (eye-tentacles, lamellate
excretory organ, innervation of the penis, etc.)
likewise have been demonstrated to be ana-
logous (cf. Plate, 1893; Boettger, 1952; Mor-
ton, 1955; Van Mol, 1967; Salvini-Plawen,
1970a; Minichev, 1975; Starobogatov, 1976).
Whereas some features (procerebrum and
cerebral glands, paired albumen gland) point
to a close root with the Archaeopulmonata (or
simply to an identical environment of origin ?),
the nervous system combined with the mutual
position of the mantle cavity and the likewise
detorted female genital opening clearly dem-
onstrate a pre-pulmonate offshot; further
characters, i.e. the so-called detorsion, vacu-
olated cells (so-called larval kidneys), and so-
called anal kidneys, in their turn evidence a
distinct relation with (Prosobranchia and)
primitive Opisthobranchia. Accordingly, the
group cannot be included as an order (vari-
ously named Ditremata, Teletremata, Systel-
lommatophora, or Gymnophila; cf. Salvini-
Plawen, 1970a) into one of the existing sub-
classes; it serves to represent an evolutionary
line (subclass) per se separate from the
Opisthobranchia as well as from Pulmonata (cf.
Stringer, 1963, Morton, 1963; Salvini-Plawen,
1970a; Minichev, 1975). With the inclusion of
the formerly enigmatic Rhodopacea, Salvini-
Plawen, (1970a) proposed the term Gymno-
morpha for the proper unit of the three re-
Classified groups (the—later—term Opistho-
pneumona chosen by Minichev, 1975, is a
misnomer, since neither the Rhodopidae, nor
the Rathousiidae or several Onchidiidae are
opisthopneumonous). In accordance with
Minichev (1975), the three groups within the
Gymnomorpha may tentatively be classified
as orders.

BIVALVIA

A most confusing situation is found within
the bivalves as concerns the supraspecific
classification. The many different systems
which were formerly and/or are actually in
use strikingly demonstrate the precarious sys-
tematic situation. The lasting uncertainty of
relationships between family groups is once
more indicated by the over-estimation of cer-
tain characters (cf. Nevesskaya et al., 1971;
Pojeta, 1971, and others) which in no way
correspond to actual comparative-anatomical
differences when compared with other mol-
luscan groups. Most of these discrepancies
are due to there being knowledge of only one
or a few special characters, and that little ef-
fort has been made to judge pathways from
the point of view of functionally synorganized
alteration; more recent investigation (cf.
Yonge, 1953, 1962; Stanley, 1972) have
demonstrated the high degree of conver-
gences and the need for thorough compara-
tive analysis.

The adaptation of some tryblidiid predeces-
sors of the Bivalvia to soft bottoms, correlated
with the elaboration of inherited cerebrally-
innervated labial organs (cf. Drew, 1901: 353,
373; Allen & Sanders, 1969; Lemche & Wing-
strand, 1959: 23 f), simultaneously resulted
in the narrowing of the foot and the lateral
compression of the body. The reduction of the
buccal mass clearly points to the probability
that mucociliary feeding by the labial palps
gradually replaced the original mode of feed-
ing, since ctenidian filter-feeding per se would
not seem suitable to replace radular feeding
at that early level of evolution (although the
latter is adequate for occasional transport of
food; cf. Stasek, 1965). Thus, the ancestors of
all Recent bivalves might have been provided
with enlarged labial flaps (palps) singling out
microorganisms and organic material from the
currents entering from the anterior during
ploughing in the sediment. That evolutionary
level may be represented by the extinct
Rostroconchia. The bent condition of the mid-
dorsal manile area finally led to the partition of
the shell gland in an early ontogenetical stage
(comp. Prodissoconch |) and resulted in the
development of the two valves as well as in
their subsequent functional equipment (ad-
ductors, hinge).

The evolutionary differentiation found in
(Recent) bivalves is basically expressed by
four developmental lines: two lines of the

MOLLUSCAN SYSTEMATICS 263

Protobranchia s. |., the Lamellibranchia $. str.,
and the Septibranchia s. str. The protobranch
groups retained the primitive state of bivalve
organization with an anterior inhalent current,
with pallial mucous tracts (hypobranchial
gland), with predominant mucus-ciliary feed-
ing by means of the labial flaps, with only a
few orifices of the midgut glands, and with
slightly modified ctenidia (cf. Yonge, 1939,
1959; Owen, 1959; Purchon, 1959). The
ctenidiobranch and ctenodont Nuculacea re-
tained further those primitive adult characters
and larval features (Pericalymma-larva; cf.
Salvini-Plawen, 1973a), but improved the
labial flaps for deposit-feeding by adapting
specialized palps with a tentacular append-
age. On the other hand, the Solemyacea are
adapted for filter-feeding of suspended mate-
rial (cf. Yonge, 1953, 1959; Allen & Sanders,
1969) with respectively enlarged, foliate
(plain-faced) ctenidia and with simplified labial
palps.

The most successful line includes the
lamellibranch bivalves (sensu Yonge, 1959,
1962; Purchon, 1959; Morton, 1963), char-
acterized by the successive alteration of the
ctenidia to filter-feeding. It may be presumed
that the origin of those (monophyletic 7?)
groups occurred by invading the littoral (pri-
mary hard bottoms) characterized by variation
of salinity (tidal zone): Both the paedo-
morphous retention of the byssus (cf. Yonge,
1962) and the development of protonephridia
(not existing in all other molluscs except lim-
nic gastropods; cf. Salvini-Plawen, 1969,
1972: 287 f & 353) positively support that
probability (cf. also Stanley, 1972), as does
the thorough adaptation from deposit- to-
wards filter-feeding itself. Rudimentarily pre-
sent in ctenidiobranch bivalves (cf. Stasek,
1965), the enlargement of the gills by elonga-
tion of the axis and the laterally connected as
well as ventrally-bent multiplied lamellae re-
sulted in the filibranch level of organization;
further specialization along that adaptive line
finally led to the eulamellibranch condition.
Especially that advanced level includes a high
radiation of specialized groups which under-
went two predominant, polyphyletic trends:
the byssal attachment gave rise to different
anisomyarian and monomyarian conditions in
epifaunal forms, whereas the preference of
(primary or secondary) infaunal habits re-
sulted in the fusion of the mantle edges and
the formation of siphons (cf. Yonge, 1953,
1962; Morton, 1963; Kauffman, 1969;
Stanley, 1972); that radiation is also obvious

in the different types of hinge-dentition (cf.
Newell, 1965; Nevesskaya et al., 1971), some
of which likewise might be polyphyletic as,
e.g. the taxodont type (cf. Pojeta & Runnegar,
1974).

A special situation is found in the septi-
branch condition. The investigations of
Nakazima (1967), of Allen & Turner (1974),
and of Bernard (1974) convincingly demon-
strate that the Verticordiacea principally be-
long to the Anomalodesmata (= Desmodonta),
the lamellibranch gills of which, however,
are gradually replaced by their own lateral
attachment-membranes increasingly forming
a septum; as in the case of the ctenidia of
other bivalves, that septum is also innervated
by the visceral ganglion. In contrast to that
condition, the septum in the Poromyacea and
Cuspidariacea is innervated by the cerebral
ganglion (cf. Bernard, 1974: 5, 18), which
proves it not to be homologous with the
verticordiacean septum. There are no ves-
tiges of ctenidia in Cuspidariacea-Poro-
myacea and the origin of their septum is ob-
scure. Purchon (1956, 1963; cf. also
Nevesskaya et al., 1971) emphasized the unity
of the septibranch stomach (including Verti-
cordiacea: Gastrodeuteia) and its possible re-
lationship to the Protobranchia (Gastroproteia).
The analysis of the Verticordiidae demon-
strates, however, that such characters of the
alimentary canal are obviously in close corre-
lation with the food (cf. Allen & Turner, 1974:
516 f), and their reliance on phylogenetic pat-
terns is dubious. Hence, the structural relation
of Cuspidariacea-Poromyacea to the Proto-
branchia with respect to the stomach becomes
questionable, as it does so concerning most
other (generally polyphyletic) characters; up
to now there is no synorganized character
confirming a closer relationship either to the
protobranchs $.1. or to the lamellibranchs s. str.

In transferring the evolutionary pathways
outlined above to a systematic arrangement,
there is clear evidence that the bivalves
should be subdivided into four major taxa, i.e.
the two protobranch groups, the lamellibranchs
5. str., and the septibranchs $. str.; this coin-
cides with the paleontologic situation under-
lined by Newell (1969: 212 ff), that the Proto-
branchia s. |. are not a homogeneous group
and can be united no longer within a single
taxon. In contrast to the polyphyletic radiation
within the lamellibranch line (s. str.), the gill
structure reflects not only the levels of organi-
zation, but also major, synorganizationally
monophyletic groups; hence the gills prove to

264 SALVINI-PLAWEN

TABLE 2. Classification of the Bivalvia.

Classis BIVALVIA Linné, 1758
|. Subclassis PELECYPODA Goldfusz, 1820

1. Superordo Ctenidiobranchia nov. (= Palaeotaxodonta Korobkov, 1954)
Ordo Nuculida Dall, 1889 (= Ctenodonta Dechaseaux, 1952, in Nevesskaya et al., 1971)

2. Superordo Palaeobranchia Iredale, 1939 (= Cryptodonta Neumayr, 1883, in Newell, 1965)
Ordo Solemyida Dall, 1889 (= Lipodonta Iredale, 1939)

Ordo Praecardiida Newell, 1965

3. Superordo Autobranchia Nevesskaya et al., 1971 (ex Autolamellibranchia Grobben, 1894)
Ordo Pteriomorpha Beurlen, 1944 (= Filibranchia Pelseneer, 1889, plus Pseudolamellibranchia
Pelseneer, 1889)
Subordo МуШта Rafinesque, 1815 (= Isofilibranchia Iredale, 1939)

Subordo Arcina Stoliczka,

1871 (=

Eutaxodonta Grobben, 1892 = Pseudoctenodonta

Dechaseaux, 1952 = Neotaxodonta Korobkov, 1954)

Subordo Pteriina Newell, 1965

Superfamilia Pterioidea Newell, 1965 (incl. Pinnoidea)
Superfamilia Limoidea D’Orbigny, 1846

Superfamilia Ostreoidea Ferussac, 1882

Superfamilia Pectinoidea Adams & Adams, 1857

Ordo Palaeoheterodonta Newell, 1965

Subordo Lyrodesmatina Scarlato & Starobogatov, 1971

Subordo Trigoniina Dall, 1889
Subordo Unionina Stoliczka, 1871
Ordo Heterodonta Neumayr, 1883

Subordo Venerina Adams & Adams, 1856
Subordo Myina Stoliczka, 1870 (= Adapedonta Cossmann & Peyrot, 1909)

Ordo Anomalodesmata Dall, 1889

Subordo Pholadomyina Newell, 1965 (incl. Verticordioidea Stoliczka)

4. Superordo Septibranchia Pelseneer, 1888/1906

Ordo Poromyida Ridewood, 1903

Superfamilia Poromyoidea Dall, 1886
Superfamilia Cuspidarioidea Dall, 1886

|. Subclassis ROSTROCONCHIA Cox, 1960

Ordo Ribeiriida Kobayashi, 1933

Ordo Ischyriniida Pojeta & Runnegar, 1976

Ordo Conocardiida Neumayr, 1891

be the most adequate single character reflect-
ing evolutionary pathways and may well serve
as superordinal taxobases. The difficulties
arise, however, with the classification within
the possibly polyphyletic lamellibranch group
(s. str.) since, according to the frequent con-
vergences, an undisputed natural grouping
has not yet convincingly been presented (cf.
e.g. Cox, 1960b; Morton, 1963; Newell, 1965,
1969; Nevesskaya et al., 1971; Pojeta, 1971,
1975, and others). At the present state of our
knowledge, the most adequate arrangement
of its groups and of the hinged bivalves in

general appears to be the classification’ as
summarized in Table 2.

Pojeta et al. (1972) elevated the former
Conocardioidea (Bivalvia) to a separate class
Rostroconchia Cox,9 characterized by a uni-
valved protoconch and a bivalved concha
without ligament, hinge teeth, and adductor
muscles; subsequently (Runnegar & Pojeta,
1974) enlarged by the Ribeiroidea (formerly
Crustacea-Conchostraca), that group in any
case ranges very close to the Bivalvia, and
may represent a more primitive evolutionary
level of bivalve organization. We doubt, how-

8With respect to the largely uniform general organization of the Bivalvia, the four main groups of Pelecypoda should be ranked
as superorders (but not as subclasses; cf. also Nevesskaya et al., 1971: 155).

9Authorship of Rostroconchia must be assigned to Cox (1960b), but not to Pojeta et al. (1972), since there is only elevation
of rank without change of contents. Similarly, the term Caudofoveata remains assigned to Boettger (1955) and not to
Salvini-Plawen (1967) who elevated the group to the status of an independent class.

MOLLUSCAN SYSTEMATICS 265

ever, Whether the characters mentioned are
prominent enough to justify the status of a
separate class: The univalved larval shell is
likewise present (though in a more advanced
evolutionary stage) in typical hinged Bivalvia
with the Prodissoconch |, and the degree of
calcification per se seems to be a very vague
argument; the lack of a typical hinge as well
as of adductors appear simply to constitute
primitive characters (as is the lack of an arti-
culamentum in the placophoran Chelodida).
Since the differences between the hinged
Bivalvia and the Rostroconchia do not appear
more prominent than do those between the
placophoran Heptaplacota and Loricata, for
example (compare also univalved and bi-
valved gastropods; cf. also Yochelson, 1978),
we merely accord the rank of subclass to the
Rostroconchia as opposed to the hinged bi-
valves or Pelecypoda. As monographically
presented by Pojeta & Runnegar (1976), the
subclass Rostroconchia is subdivided in three
orders, the Ribeiriida, Ischyriniida, and
Conocardiida.

CEPHALOPODA = SIPHONOPODA

In re-establishment of the findings of Iher-
ing (1877: 250-269) and Dietl (1878: 100-
108), Young's recent investigations (1965: 8-
10; 1971: 1, 11) likewise confirm the innerva-
tion of the head-tentacles or arms to be in fact
cerebral (and not pedal): The pedal-complex
sensu lato consists of two structurally different
sections with different interconnections with
other parts of the central nervous mass. The
frontal (= brachial) section receives its con-
nectives directly from the cerebral ganglia; in
contrast, the hind (= infundibular) section of
the complex is truly pedal (innervating the
funnel) and is connected with the magnocellu-
lar (= lateral) region, which in turn is linked
with the cerebral (= supraesophageal) nerve
mass. Despite the secondary topographic fu-
sion of the brachial and infundibular/pedal
masses, there is distinct separation as con-
cerns the nerve bundles and their innervation
areas. The pedal gland (funnel gland, funnel
organ) fully corresponds with that evidence
since it is situated in direct connexion with and
in a frontal position of the adenopod foot
(= funnel). In accordance with that (reestab-
lished) elucidation, the term ‘Cephalopoda’

clearly is erroneous and should be aban-
doned in favour of Siphonopoda (Lankester,
1877, nec G. O. Sars, 1878).

In consideration of the evolutionary sys-
tematic condition within the Cephalopoda/
Siphonopoda, there are striking differences
concerning the classification mainly due to the
radiating fossil branches. Whereas the
Coleoidai0 have been recently dealt with
thoroughly by Mangold-Wirz & Fioroni (1970),
extinct groups are subject to considerable
controversy. This becomes immediately evi-
dent within the Coleoida when comparing the
analyses of Jeletzky (1966) and Teichert
(1967); both authors, however, coincide in the
separation of the Aulacocerida and Phrag-
moteuthida as distinct groups, which is like-
wise accepted by Fioroni (1974). The
Coleoida (= Endocochlia of Schwartz, 1894
= Dibranchiata of Owen, 1826), including the
Belemnites, are generally accepted as having
evolved from Bactritites (= Michelinocera-
tites). Since Erben (1964, 1966) was able to
demonstrate that the ammonites likewise
evolved from Bactritites (originating within the
Orthocerida-Sphaerorthoceridae according to
Ristedt, 1968), he supported an earlier sug-
gestion concerning the contradictory structure
of the siphon and of septa in ammonites and
nautiloids respectively. The group known
under the vague term of Ectocochlia (or
Tetrabranchiata) could therefore no longer be
upheld, and the closer relationship of the
Ammonoida and Coleoida has been mani-
fested. This has subsequently been sup-
ported by the elucidation of some internal,
partly soft structures in early ammonities (cf.
Kolb, 1961; Close, 1967; Lehmann, 1966;
1967a, b, 1976; Zeiss, 1968; Reyment,
1972a, »), indicating that the ammonites pre-
sumably were provided with a radula, an ink-
sac, a fairly low number of arms, and sexual
dimorphism, as have the Coleoida. Lehmann
(1967a) consequently proposed a new classi-
fication of the class: Angustiradulata (Am-
monoida and Coleoida) and Lateradulata
(Nautiloida s.l). This latter radula with 13
longitudinal rows of teeth is merely known in
the Recent Nautilus and a close relative
Palaeocadmus (cf. Solem & Richardson,
1975), but nothing is known so far about the
radulae of distantly related groups; moreover,
there is some indication that Nautilus itself
represents a specialized form even within the

1OFollowing Recommendation 29A of the International Code of Zoological Nomenclature, the taxonomic ending “-oidea”
should uniformly be restricted to superfamilies (family groups); accordingly, a change of the subclass endings to “-oida” is

proposed.

266 SALVINI-PLAWEN

Nautiloida sensu lato (cf. Ihering, 1881; H.

Hoffmann, 1937; Flower, 1955; Lehmann,
19676; Mangold-Wirz & Fioroni, 1970).
Lehmann’s proposition, therefore, merely

holds good for his own Angustiradulata.

A subdivision of the class into only two taxa
(as proposed by Lehmann) is neither morpho-
logically nor phylogenetically satisfactory (cf.
Donovan, 1964; Teichert, 1967; Mangold-
Wirz & Fioroni, 1970). As stated by Flower
(1955) and Teichert (1967), the primitive
orthoconic groups and groups closely related
to them differ considerably from the Nautiloida
$. str. Likewise, orthoconic Endocerida (in-
cluding Intejocerina), Actinocerida, and Dis-
cosorida, even if their organizations are more
distinctive, cannot be regarded as represent-
ing ranks of subclasses since many of their
features are repeated within other groups (cf.
Teichert, 1967: 204), and since they appear
merely to be smaller offshoots of the primitive
Ellesmerocerida (cf. Flower, 1955; Donovan,
1964: Teichert, 1967). All these more or less
closely related groups may consequently be
united in one separate subclass, Ortho-
ceroida (see Table 4).

MOLLUSCA

This presentation so far demonstrates that
increase in knowledge implies alterations and
even revisions of our understanding of phylo-
genetic pathways, and hence of systematic
representation. This reflexion of permanent
systematic flux also concerns the molluscs as
a whole when emphasizing the evolutionary
morphologically qualitative importance of
organizations irrespective of quantitative con-
tents (compare: Gastropoda with Scapho-
poda, etc.).

Based upon an extensive study of the lower
molluscs, Salvini-Plawen (1972) also did a
comparative analysis of molluscan organiza-
tion in general, especially with respect to
phylogenetic pathways from the zoological
(neontological) point of view; simultaneously,
Stasek (1972) presented a study coming to
similar conclusions in general outline, differ-
ing in detail, however, owing to his emphasis
on the advanced groups only.

As summarized in Figs. 3-5, the evolution-
ary radiation within the Mollusca is not a
weighted one, but dominates along the line of
mantle(-foot)-differentiation culminating with
the Siphonopoda (cephalopods); this condi-
tion also contributed to the under-estimation

of the lower molluscs. The earliest confirm-
able evolutionary branching already took
place at the level of very primitive molluscan
organization, still characterized by an overall
ventral gliding surface, by a merely circum-
posterior mantle cavity, and by an aculiferan
mantle cover (chitinous cuticle with em-
bedded aragonitic scaly bodies; cf. Degens et
al., 1967: 640; Beedham & Trueman, 1968;
Salvini-Plawen, 1969, 1972; Peters, 1972;
Stasek, 1972; Carter & Aller, 1975; Trueman,
1976; Salvini-Plawen & Boss, 1980). The
preference and subsequent adaptation of
some populations to sediment-burrowing
habits finally resulted in the Recent Caudo-
foveata, during their course of which the lo-
comotory surface was restricted to its cere-
brally-innervated section, i.e. the pedal shield.
That evolutionary line of Scutopoda, including
only the Caudofoveata, is contrasted phylo-
genetically to the Adenopoda: Selective pres-
sure upon the improvement of food-uptake by
the organisms while steadily gliding by means
of cilia led to the individualization of a snout.
The trend to release the oral region from its
earlier locomotory function induced the ex-
tension of the posterio-lateral mantle grooves
towards the anterior to unite preorally. Addi-
tionally, the locomotory surface hence con-
fined to the purely ventrally-innervated sec-
tion, i.e. the foot, was subsequently supported
in its function by the selection of an anterior
accumulation of a distinct follicular gland.
That pedal gland, innervated by the first
nerves of the ventral/pedal system, proves
itself to be a genetically well-established dif-
ferentiation (cf. Salvini-Plawen, 1972: 304 ff).
In its interdependent evolutionary synorgani-
zation with a peripedal-preoral mantle cavity it
distinctly defines the phylogenetic branch of
Adenopoda, including all (Recent as well as
extinct) molluscan groups except the Caudo-
foveata.

Two adenopodan groups, the Soleno-
gastres and Placophora, not only share the
still primitive aculiferan mantle cover; they are
also synapomorphously tied together by the
rudiment of seven transverse rows of calcar-
eous bodies in the larvae (see Fig. 2) which
distinctly prove the monophyletic origin of
both groups within the Adenopoda. Their later
differentiation of the mantle cover demon-
strates, however, the subsequent specific
deviation: re-disintegration of the cover of
spicules in the Solenogastres, and consolida-
tion of the juxtaposed bodies to seven shell
plates in early Placophora (Heptaplacota).

MOLLUSCAN SYSTEMATICS 267

The ancestral, common character of trans-
verse rows of middorsal scales in both
Solenogastres and Placophora, as well as the
subsequent tendency to consolidate these
juxtaposed scaly elements to become homo-
geneous formations, is likewise obvious in the
solenogastre Nematomenia (?) protecta: the
scaly mantle cover of this species is char-
acterized ‘by three peculiar shields at the
dorsal side of the head, which are clearly
formed by coalescence of several juxtaposed
small scales; apparently about 10 small
scales have been united by lateral fusion, so
that the original separation is merely indicated
by a number of indentations at the posterior
rim. | always find three such shields, the an-
teriormost of which is located close to the an-
terior end of the animal and partly imbricates
the immediately subsequent second shield.
The third shield, on the other hand, is sepa-
rated from the middle one by a small number of
ordinary scales” (translated from Thiele, 1913:
39).

Placophora with eight (!) plates, however,
must be considered ancestral to the Conchi-
fera. Since these placophorans bend and roll
up ventrally—effected by the primitive char-
acter of a longitudinal muscle bundle close to
each mantle edge, likewise present in
Solenogastres and even in Caudofoveata—
not prior to the prevention of that bending
(probably by living in an undisturbed environ-
ment) the centers of plate-formation concen-
trated and fused to create a single, homo-
geneous concha; Fig. 3 demonstrates the
respective synorganized alterations (cf.
Salvini-Plawen, 1972; Haas, 1972 versus
Beedham & Trueman, 1967; Stasek &
McWilliams, 1973). This fusion was followed
by concentration of the dorsoventral (shell-
pedal) muscle bundles from 16 to 8, and by
further elaboration (jaws, statocysts, subrectal
commissure). The recent tryblidiid Neopilina
characteristically demonstrates a far-reaching
‘connecting link'-configuration in combining
characters of both Placophora and Conchi-
fera (dorsoventral musculature, esophageal
and digestive glands, slender intestine, sub-
radular organ; cf. Boettger, 1959; Salvini-
Plawen, 1972, and others).

In regard to the radiation within the Conchi-
fera, unanimous opinion seems to exist from
the zoological as well as from the paleonto-
logical point of view that the Bivalvia (includ-
ing the Rostroconchia) and the Scaphopoda
represent a somewhat closer relationship,
mainly due to the developmental configura-

tion of the mantle-shell (cf. Salvini-Plawen,
1972: 312; Pojeta & Runnegar, 1976: 43; and
others). On the other hand, the Tryblidiida,
Bivalvia and Scaphopoda have retained the
peripedal mantle cavity of the typical Adeno-
poda, and the merely single pair of ctenidia in
Bivalvia may therefore serve additionally to
indicate that these organs are secondarily
pluralized in Placophora and Neopilina. In
contrast, in Bellerophontida partim and in
Gastropoda, as well as in Cephalopoda/
Siphonopoda, the mantle cavity is confined to
the (morphologically) posterior body in con-
nexion with the increase of cephalization and
the heightening of the shell. That condition
clearly demonstrates that gastropods and
siphonopods were derived from advanced,
high-cyrtoconic Galeroconcha in contrast to
bivalves and scaphopods originating in more
primitive, cap-shaped galeroconchs. The
closer ancestral relationship of Cephalopoda/
Siphonopoda and Bellerophontida-Gastro-
poda (cf. also Yochelson et al., 1973) might
also be indicated by the possible homology of
the eyes (cf. Salvini-Plawen & Mayr, 1977),
presumably differentiated already in the more
advanced galeroconchs. There is no substan-
tiated reason, however, to join the three
groups systematically into one supertaxon,
and the reverse tendency by Mangold-Wirz &
Fioroni (1970) and Fioroni (1974) to classify
the siphonopods as separate from all other
Conchifera is based merely upon present day
differences; it disregards, however, the not-at-
all extraordinary phylogenetic point of view,
according to which there is continuous evolu-
tion and radiation (cf. Yochelson et al., 1973:
Erben, 1964, 1966; Ristedt, 1968, and
others).

According to that analysis, one could cer-
tainly subdivide the Conchifera with respect to
possible evolutionary pathways (see Fig. 4),
and classify them, e.g. as Ventropoda or
Archaeoconcha (Galeroconcha and Gastro-
poda), Siphonoconcha (Siphonopoda/
Cephalopoda), and Loboconcha (Bivalvia and
Scaphopoda); this grouping would be more
adequate than a subdivision into Cyrtosoma
and Diasoma as proposed by Runnegar &
Pojeta (1974) which, in addition, relies on a
partially imagined or even incorrect character
(Tryblidiida; Scaphopoda). All these attempts
are mere supposition, since they still appear to
be more or less contestable speculations. The
Conchifera are a phylogenetically as well as
morphologically compact group ancestrally
tied to the Galeroconcha, and subdivision of

268 SALVINI-PLAWEN

them at our present state of knowledge is not
justified.

In consideration of the widely substanti-
ated, comparative-anatomical as well as evo-
lutionary levels within the molluscan organiza-
tion, only three essential evolutionary steps
are conspicuous: (1) The restriction of the
ventral locomotory surface to the ventrally-
innervated section combined with beginning
cephalization and the preoral extension of the
mantle cavity; this evolutionary differentiation
separates the Adenopoda from the Scuto-
poda. (2) The elaboration of a shelled mantle
cover (Placophora) correlated with the begin-
ning concentration of the dorsoventral muscu-
lature, and accompanied by {пе specific dif-
ferentiation of the alimentary сапа! s. |.
(esophageal and midgut glands, slender and
winding intestine, subradular sense organ;
differentiation of the pericardioducts as excre-
tory organs 7); that evolutionary step within
the Adenopoda separates the Placophora
and Conchifera from the Solenogastres. (3)
The establishment of a homogeneous
concha, accompanied by the differentiation of
the jaws, the statocysts, the subrectal com-
missure, and the cerebrally-innervated tenta-
cle formations (preoral tentacles and velum in
Neopilina, cephalic tentacles in Gastropoda,
palps in Bivalvia, captacula in Scaphopoda,
arms in Cephalopoda/Siphonopoda; cf.
Lemche & Wingstrand, 1959; Allen &
Sanders, 1969; Grobben, 1886; Gainey,
1972: and others); these synapomorphies
separate the Conchifera.

An adequate classification would have to
reflect the above steps (Fig. 4) systematically;
this, however, would also result in an unjusti-
fied over-accentuation of the Solenogastres.
In an endeavour not to hypertrophize the
specialist's own group, it must be stated that
the Solenogastres are quite distinct from the
Caudofoveata (see Adenopoda versus Scuto-
poda), but within the Adenopoda they consti-
tute merely an early side branch. The close
relationship of the Placophora and Soleno-
gastres, synapomorphously tied together by
the rudiments of seven transverse rows of
juxtaposed spicules (see Figs. 2-3), justifies
including both groups under one taxon for
which the appropriate term Heterotecta may
be coined (defined as Adenopoda without
concha and characterized by the develop-
mental rudiment of seven transversely ar-
ranged rows of juxtaposed calcareous bodies
at the middorsal mantle; these bodies have
different fates). Such a classification also ap-

pears more adequate in regard to the morph-
ological weight of the phylogenetically most
successful Conchifera, as well as concerning
the reasonable subdivision of the Adenopoda
solely into two groups, i.e. to separate the
Conchifera from the collectively more primi-
tive Placophora and Solenogastres. Conse-
quently, the systematic grouping of the Mol-
lusca results as compiled in Fig. 5 and Table
9:

OTHER TAXA

The Scaphopoda do not need special dis-
cussion. Their somewhat close relationship to
the Bivalvia has been mentioned above.
Emerson (1962) as well as Palmer (1974a, b)
have reclassified the group, Palmer (1974a)
introducing two orders Dentaliida and Sipho-
nodentaliida (compare footnotes 3 and 10).

There are several terms and taxa associ-
ated with the molluscs still to be discussed
shortly. The familiar term Aplacophora (Iher-
ing, 1876) has already been dealt with; it must
be dropped due to the diphyletic origin of the
Caudofoveata and Solenogastres.

The term Amphineura (Ihering, 1876) was
Originally created because of the seemingly
similar nervous systems in Aplacophora and
Placophora; more recently, many scientists
tend to confine the term to the Placophora.
Since neither the Solenogastres, nor the
Caudofoveata still possess a truly amphi-
neural nervous system (i.e. two separate
pairs of medullary cords (= without ganglia
formation) provided with irregular ventral as
well as lateroventral interconnexions), this
condition is still represented only in Placo-
phora and—although already more special-
ized—also in Neopilina. Other configurations
only reflect the general tetraneury typical of all
Mollusca.

The term Aculifera (Hatschek, 1891) is
more adequate when considering the aplaco-
phoran and polyplacophoran groups—as
originally introduced and as used by Salvini-
Plawen (1S68b, 1969, 1972); it has been mis-
leadingly limited by Stasek (1972; and copied
by Pojeta & Runnegar, 1976) to the aplaco-
phoran groups. This taxon, however, shares
with the ‘Aplacophora’ disregard of the evolu-
tionary branching into Scutopoda and Adeno-
poda, thus including three different groups
having conservatively retained the symplesio-
morphous character of the mantle cover with
cuticle and aragonitic bodies.

MOLLUSCAN SYSTEMATICS 269

TABLE 3. Higher classification within molluscs.

Subphylum

Infraphylum/Superclassis

Classis

Aculifera
current
grouping

(Gótting, 1974;

Lehmann, 197€!

Caudofoveata

Solenogastres
Placophora

Monoplacophora
Gastropoda

Conchifera

Scutopoda
Heterotecta

corrected
version

Conchifera

Bivalvia
Scaphopoda
Cephalopoda

Caudofoveata

Solenogastres
Placophora

——

Galeroconcha
Gastropoda
Siphonopoda
Bivalvia
Scaphopoda

Scutopoda

ohylogenetically

adequate
classification

Adenopoda

Caudofoveata

J Solenogastres

Heterotecta
\ Placophora

Galeroconcha
Gastropoda
Siphonopoda
Bivalvia
Scaphopoda

Conchifera

The enigmatic Late Cambrian Matthevia
still remains one of the ‘problematica’ with
molluscan affinities (cf. Yochelson, 1978).
Yochelson (1966) reviewed recent records
and erected a new class for the genus; on the
other hand, Runnegar & Pojeta (1974) sug-
gest that the two, co-occurring, somewhat
unequal and massive shells with two tapering
cavities each represent the conical values of a
primitive chiton. Disregarding the evidence for
a very different evolution of the Placophora
(see Figs. 3 & 5) than that speculated by Run-
negar & Pojeta, it remains here to stress (1)
that the placophoran plates “in no way re-
semble the hard pieces of Matthevia” (Yoch-
elson, 1966: 8) even when compared with
Chelodida, and (2) that the conical internal
cavities of the shells separated by a strong
septum are situated in succession but not in
juxtaposition. If compared to Placophora, both
the latter characters point to highly special-
ized features, the paired dorsoventral muscle
bundles being then concentrated apically (in
contrast to Tryblidiida and Placophora). The
strange reconstruction of Matthevia by Yoch-

elson (1966), however, raises a question as to
how such organisms should have been adap-
tively selected; in contrast to the opinion of
Yochelson, the reconstructed condition is not
streamlined (compare Patella, Ancylus, etc.,
which press their anterior shell margin to the
bottom), and the animal cannot retract into the
small cavities (which are, additionally, filled by
“powerful muscles”)—and the size of the or-
ganisms is purely speculative. Is it not possi-
ble that the soft parts of the body greatly ex-
ceed the shell(s) (analogously to Bivalvia-
Pholadoidea or -Clavagelloidea)?

The Stenothecoida with their two symmetri-
cal and unequal hingeless valves must be
placed incertae sedis until more information
can be offered in favour of a distinct relation-
ship to another group (within or even outside
of the molluscs; cf. also Yochelson, 1978).
While Yochelson’s reconstruction (1969) is
not quite satisfactory as concerns a ‘mollusk,’
the interpretation of Runnegar & Pojeta
(1974: 316) as “bivalved monoplacophorans,
with the lower valve formed by the sole of the
foot” appears to be pure speculation.

270 SALVINI-PLAWEN

TABLE 4. Classification of the Mollusca proposed herein (+ = extinct).

Phylum MOLLUSCA Cuvier, 1795
Subphylum SCUTOPODA Salvini-Plawen, 1978

Classis CAUDOFOVEATA Boettger, 1955
Ordo Chaetodermatida Simroth, 1893

Subphylum ADENOPODA Salvini-Plawen, 1971

Infraphylum/Superclasssis HETEROTECTA nov.
Classis SOLENOGASTRES Gegenbaur, 1878
Superordo Aplotegmentaria Salvini-Plawen, 1978
Ordo Pholidoskepia Salvini-Plawen, 1978
Ordo Neomeniomorpha Pelseneer, 1906 (emend.)
Superordo Pachytegmentaria Salvini-Plawen, 1978
Ordo Sterrofustia Salvini-Plawen, 1978
Ordo Cavibelonia Salvini-Plawen, 1978
Classis PLACOPHORA Ihering, 1876
+ Subclassis HEPTAPLACOTA nov.
Ordo Septemchitonida Bergenhayn, 1955
Subclassis LORICATA Schumacher, 1817
+ Ordo Chelodida Bergenhayn, 1943
+ Ordo Scanochitonida Starobogatov & Sirenko, 1975
Ordo Lepidopleurida Thiele, 1910
Ordo Chitonida Thiele, 1910

Infraphylum/Superclassis CONCHIFERA Gegenbaur, 1878
Classis GALEROCONCHA nov.
Ordo Tryblidiida Wenz, 1938 = Monoplacophora Odhner in Wenz, 1940
+ Ordo Bellerophontida Ulrich & Scofield, 1897 = Belleromorpha Naef, 1911
Classis GASTROPODA Cuvier, 1795
Subclassis PROSOBRANCHIA Milne-Edwards, 1848
Ordo Archaeogastropoda Thiele, 1925
Subordo Vetigastropoda nov.
Subordo Docoglossa Troschel, 1866
Subordo Neritopsina Cox, 1960
Ordo Caenogastropoda Cox, 1960
Subordo Mesogastropoda Thiele, 1925
Subordo Neogastropoda Thiele, 1929
Subclassis PULMONATA Cuvier, 1817
Ordo Archaeopulmonata Morton, 1955
Ordo Basommatophora Keferstein, 1864
Ordo Stylommatophora Schmidt, 1855
Subclassis GYMNOMORPHA Salvini-Plawen, 1970
Ordo Onchidiida Rafinesque, 1815
Ordo Soleolifera Simroth, 1908 = Veronicellida Gray, 1840
Ordo Rhodopida Fischer, 1883
Subclassis OPISTHOBRANCHIA Milne-Edwards, 1848
Ordo Pyramidellimorpha Fretter, 1979
Ordo Cephalaspidea Fischer, 1883
Ordo Anaspidea Fischer, 1883
Ordo Saccoglossa Ihering, 1876 (= Ascoglossa Bergh, 1879)
Ordo Notaspidea Fischer, 1883
Ordo Nudibranchia Ducrotay-Blainville, 1814
Ordo Anthobranchia Ferussac, 1819
Classis BIVALVIA Linne, 1758
Subclassis PELECYPODA Goldfusz, 1820
Superordo Ctenidiobranchia nov.
Ordo Nuculida Dall, 1889
Superordo Palaeobranchia Iredale, 1939
Ordo Solemyida Dall, 1889
+ Ordo Praecardiida Newell, 1965
Superordo Autobranchia Nevesskaya et al., 1971
Ordo Pteriomorpha Beurlen, 1944
Ordo Palaeoheterodonta Newell, 1965

MOLLUSCAN SYSTEMATICS 271

TABLE 4 (Continued).

Ordo Heterodonta Neumayr, 1883
Ordo Anomalodesmata Dall, 1889
Superordo Septibranchia Pelseneer, 1888/1906

Ordo Poromyida Ridewood, 1903

+ Subclassis ROSTROCONCHIA Cox, 1960

Ordo Ribeiriida Kobayashi, 1933

Ordo Ischyriniida Pojeta & Runnegar, 1976
Ordo Conocardiida Neumayr, 1891

Classis SCAPHOPODA Bronn, 1862
Ordo Dentaliida Palmer, 1974

Ordo Siphonodentaliida Palmer, 1974
Classis SIPHONOPODA Lankester, 1877 = CEPHALOPODA Schneider, 1784
+ Subclassis ORTHOCERATOIDA Kuhn, 1940
Ordo Ellesmerocerida Flower, 1950

Ordo Orthocerida Kuhn, 1940
Ordo Ascocerida Kuhn, 1949

Ordo Discosorida Flower, 1950
Ordo Endocerida Teichert, 1933
Ordo Actinocerida Teichert, 1933

Subclassis NAUTILOIDA Lamarck, 1812

+ Ordo Oncocerida Flower, 1950

Ordo Nautilida Agassiz, 1847

+ Ordo Tarphycerida Flower, 1950

+ Subclassis AMMONOIDA Lamarck, 1812

Ordo Bactritida Shimanskij, 1951

Ordo Goniatitida Hyatt, 1884

Ordo Ammonitida Agassiz, 1847
Subclassis COLEOIDA Bather, 1888
+ Ordo Aulacocerida Jeletzky, 1965

+ Ordo Belemnitida Zittel, 1885
Ordo Sepiida Naef, 1916

+ Ordo Phragmoteuthida Jeletzky, 1964

Ordo Teuthida Naef, 1916

Ordo Vampyromorpha Grimpe, 1917
Ordo Octobrachia Boettger, 1952 (pro Octopoda Leach, 1817)

en

The following taxa are considered to in-
clude Mollusca dubiosa: Hyolitha, Tentaculita,
Agmata and Jinonicellina. There is need of
much more information whether the Hyolitha
(cf. Marek & Yochelson, 1964, 1976; Run-
negar et al., 1975; Yochelson, 1978), the Ten-
taculita (cf. Blind, 1969; Runnegar et al., 1975),
the Agmata (Volborthella, Salterella; cf.
Yochelson, 1977b; Glaessner, 1976), and the
Jinonicellina (cf. Runnegar, 1977; Yochelson,
1977a; Pokorny, 1978) are actually of mol-
luscan organization or rather belong to other
shelled organisms (compare, e.g., Glaessner,
1976 for the ‘Agmata’). With respect to the
hyoliths, we doubt the interpretation given by
Runnegar et al. (1975) concerning the posi-
tion of the muscle bundles, the insertions of
which are preserved on both the operculum
and cone; such strong bundles indicate the
need for strenuous performance and cor-
respondingly the need for rigid structures of
insertion, but not connective tissue. More-
over, and in addition to the critique by Marek
& Yochelson (1976), in firmly shelled organ-
isms (and in contrast to deformable tube-

dwelling bodies like sipunculids or some
polychaetes ) pressure upon the body fluid can
easily be exercised by circular musculature;
only the retraction ofthe body needs compact
musculature. Since muscle bundles from the
dorsal to the ventral side of the shell itself
serve no purpose whatsoever, the bundles
might have inserted either at acompact organ
(i.e. radula bolster, cartilage-like structures,
and other) or rather—and more likely—at the
operculum with its five pairs of muscle scars
(cf. Yochelson, 1974; compare also the
rudists = Hippuritoidea).

FINAL DISCUSSION AND PROPOSAL

The Mollusca constitute one of the best de-
fined groups within the animal kingdom and
are distinguished by several synorganized
characters original to the phylum, viz. the
dorsal integument secreting chitinous cuticle
and/or calcareous formations = the aplaco-
phoran/polyplacophoran/conchiferan mantle;
a respiratory mantle cavity with ctenidia,

272 SALVINI-PLAWEN

mucous tracts and body outlets; the ventral
body surface serving for locomotion by means
of cilia and mucous glands as well as partly of
dorsoventral musculature; the gono-peri-
cardial complex and an open circulatory sys-
tem; a series of paired dorsoventral muscle
bundles and—primitively—a pair of longitu-
dinal muscle bundles along the margin caus-
ing the animal to roll up; the radula; and the
tetraneury associated with a pallial sense or-
gan (terminal sense organ, osphradia).
Owing to the fact that most molluscs pro-
duce fossilizable hard structures, we fortu-
nately are able to study a great deal of mol-
luscan phylogeny by means of these shell
formations within different levels and groups.
That condition, however, largely suppresses
the importance and morphologically equiva-
lent significance of other groups of molluscs
of which no fossils have been handed down.
Supported by the overwhelming quantitative
dominance of the shell- (especially concha-)
bearing molluscs, that discrepancy as con-
cerns the comparative importance of different
molluscan groups has become nearly inexcu-
sable. In consideration of phylogenetic re-
construction and the endeavour to trace evo-
lutionary pathways, two essential reflexions
should always be taken into account: (1) Any
adaptive alteration of a character is tied at any
time to anatomical and functional interde-
pendence on syn-organization; (2) a close,
monophyletic relationship, i.e. the common
descendant from an ancestral organization, is
only substantiated by new character(s) ac-
quired in common (syn-apomorphies),
whereas the common retention of conserva-
tive characters (syn-plesiomorphies) merely
demonstrate a more general relationship with-
in a superior frame. Thus, many speculations
and (mis-)interpretations, about Neopilina for
example, could have been avoided under
these premises, as well as the revival of the
taxon ‘Aplacophora’ (cf. Scheltema, 1978).
In consideration of the evolutionary path-
ways within the Mollusca, there are four es-
sential steps of progressive differentiation
(Scutopoda/Adenopoda, Solenogastres/
Testaria, Placophora/Conchifera, and radia-
tion of Conchifera); since the Caudofoveata
and Solenogastres are only tied together by
symplesiomorphies, and since the Soleno-
gastres-Placophora, as well as the Placo-
phora-Conchifera are each tied by synapo-
morphies, the phylogenetic lines are obvious
(Figs. 3-5). Transposed to usable linear sys-
tem (cf. also Mayr, 1974), these conditions

may be rendered by the final proposal as pre-
sented in Table 4.

SUMMARY

A reconsideration of systematic problems in
the Mollusca raised by various recent studies
results in the discussion of phylogenetic path-
ways and in the presentation of a correspond-
ingly modified higher classification (as sum-
marized in Fig. 5 and Table 4):

1) The original, common organization of Mol-
lusca, characterized by an overall ventral
gliding surface and а posterior-lateral
mantle cavity, according to further way of
life differentiated along two basic evolu-
tionary lines: a) the burrowing Scutopoda
with the locomotory surface restricted to
the cerebrally-innervated section (Caudo-
foveata only); b) the continuing gliding-
creeping Adenopoda with the locomotory
surface confined to the ventrally-innervat-
ed section, with the differentiation of a
rudimentary head, with a preorally extend-
ed mantle cavity, and with a distinct pedal
gland (Solenogastres, Placophora, and
Conchifera).

2) Within the Adenopoda, both the Soleno-
gastres and Placophora are monophyleti-
cally (Synapomorphously) interconnected
by the rudimental mantle differentiation of
seven middorsal, transversely arranged
rows of juxtaposed calcareous bodies (cf.
Fig. 2). Accordingly, the Septemchitonida
are raised to a separate subclass Hepta-
placota, and both Solenogastres and
Placophora are classified together as
Heterotecta, separated from the Conchi-
fera.

3) Within that classification, the Caudo-
foveata constitute an isolated, early sepa-
rated group (Scutopoda) interconnected to
the Solenogastres and/or other molluscs
merely by the conservative presence of
ancestral (symplesiomorphous) char-
acters. Placophora and Conchifera are in-
terconnected by several synapomorphous
characters; herein, the organization of
Neopilina constitutes a connecting link.

4) No sufficient characters are obvious to
serve for justified supraclasses within the
Conchifera.

5) A reconsideration of the torsion process
leads to the presumption that the two
separate torsional phases reflect different
evolutionary adaptations. Correlative to

MOLLUSCAN SYSTEMATICS 273

that interpretation, the Bellerophontida
(Belleromorpha) are considered to have
been untorted organisms and are hence
reclassified together with the Tryblidiida
(Monoplacophora) within the new taxon
Galeroconcha, and the pallial asymmetry
of the higher gastropods other than
Archaeogastropoda is regarded to be a
paedomorphous character.

6) Onchidiacea, Soleolifera, and Rhodo-
pacea are demonstrated to represent a
separate line (Subclass Gymnomorpha) dis-
tinct from both the Pulmonata as well as
the Opisthobranchia. The Doridacea must
be separated from the Nudibranchia as a
separate order Anthobranchia.

7) The Rostroconchia are regarded as a sub-
class of the Bivalvia, and the hinged,
pelecypod Bivalvia may phyletically be
grouped in four lines according to way of
life (feeding, differentiation of gills); the
Poromyida must be classified as a sepa-
rate group (Septibranchia).

8) The recent confirmation that the arms of
cephalopods are cerebrally-innervated or-
gans favours the term Siphonopoda for the
class. The various early lines of fossil
Siphonopoda (cephalopods) are classified
within the taxon Orthoceroida and set
apart from Nautiloida, Coleoida, and Am-
monoida.

9) Other taxa, groups, and terms are briefly
discussed, with special emphasis on the
avoidance of hypertrophy of systematic
categories which are not justified compar-
atively.

ACKNOWLEDGEMENTS

| would like to thank my colleague and
friend Prof. Dr. Friedrich Steininger (Institut
für Paläontologie, Universität Wien, Austria)
for scientific information and paleobiological
data given during personal discussions.

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YOCHELSON, E. L., 1969, Stenothecoida, a pro-
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YOCHELSON, E. L., 1974, Redescription of the
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YOCHELSON, E. L., 1977a, Comments on Jano-
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YOCHELSON, E. L., 1977b, Agmata, a proposed
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YOCHELSON, E. L., 1978, An alternative approach
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278

SALVINI-PLAWEN
ZUSAMMENFASSUNG

EINE NEU-BEURTEILUNG DES SYSTEMS DER
MOLLUSKEN (PHYLOGENIE UND GROSZ-GRUPPIERUNG)

Luitfried v. Salvini-Plawen

Eine Analyse verschiedener Unstimmigkeiten, welche durch in jüngerer Zeit durchgefuhrte
Beiträge hinsichtlich phylogenetischer Zusammenhänge und systematischer Groszgruppierung
entstanden, fúnrt zur Darlegung neuerer Vorstellungen zum stammesgeschichtlichen Entwick-
lungsablauf innerhalb der Mollusken und zu einem entsprechend modifizierten System (vgl. Fig.
5 und Tabelle 4):

1) Die ursprüngliche, gemeinsame Molluskenorganisation, welche u.a. durch eine die gesamte
Ventralfläche einnehmende Gleitsohle und einen posterio-lateralen Mantelraum gekenn-
zeichnet war, spaltete sich entsprechend der Lebensweise in zwei Entwicklungslinien auf: a)
in die grabenden Scutopoda mit Einschränkung des Lokomotionsorganes auf den cerebral
innervierten Abschnitt. (nur Caudofoveata), und b) in die weiterhin gleitend-kriechenden
Adenopoda mit Einschränkung der Lokomotionsfläche auf den ventral innervierten Abschnitt,
mit der beginnenden Differenzierung eines Kopfabschnittes, mit einem sich praeorad
ausdehnenden Mantelraum, und mit der Ausbildung einer distinkten Fuszdrüse (Soleno-
gastres, Placophora, Conchifera).

2) Innerhalb der Adenopoda sind die Solenogastres und Placophora durch die monophyletische
(synapomorphe) Ausbildung von sieben Querreihen nebeneinanderliegender Kalkkörper in
der Mantelmitte verbunden (vg. Fig. 2). Dementsprechend werden die Septemchitonida als
eine eigene Unterklasse Heptaplacota abgetrennt, und Solenogastres wie Placophora
werden zusammen als Heterotecta den Conchifera gegenübergestellt.

3) Innerhalb dieses Gesamtrahmens stellen die Caudofoveata daher eine isolierte Gruppe dar
(Scutopoda), welche mit den Solenogastres und/oder anderen Mollusken nur durch konser-
vativ erhaltene (symplesiomorphe) Merkmale verbunden sind. Placophora und Conchifera
sind durch mehrere synapomorphe Merkmale verbunden; Neopilina stellt hierbei eine ver-
mittelnde Brückenorganisation dar.

4) Innerhalb der Conchifera lassen sich bisher keine ausreichenden Verbindungen erkennen,
welche die Errichtung von Uberklassen rechtfertigen würden.

5) Eine Analyse der Torsionsvorgänge führt zu der Annahme, dasz die ontogenetische Zwei-
phasigkeit auf zwei evolutiv verschiedene Anpassungsprozesse zurückzuführen sind.
Entsprechend dieser Aufschlüsselung werden die Bellerophontida (Belleromorpha) als
untortierte Organismen aufgefasst und zusammen mit den Tryblidiida (Monoplacophora) im
Rahmen einer Klasse Galeroconcha neu eingereiht, wie auch die Asymmetrie des Mantel-
raumkomplexes bei den Schnecken mit Ausnahme der Archaeogastropoda als eine Paedo-
morphie interpretiert wird.

6) Onchidiacea, Soleolifera und Rhodopacea lassen sich als eine eigene, von Pulmonata wie
Opisthobranchia unabhängige Entwicklungslinie feststellen (Unterklasse Gymnomorpha).
Die Doridacea sind als eigene Ordung Anthobranchia von den Nudibranchia abzutrennen.

7) Die Rostroconchia werden als eine Bivalvia-Unterklasse (und nicht als eigene Klasse)
aufgefasst. Die mit Schlosz versehenen pelecypoden Bivalvia können entsprechend ihrer
Lebensweise (Ernährung, Kiemendifferenzierung) in vier Entwicklungslinien gruppiert
werden; die Poromyida sind hierbei als eigene Gruppe zu führen (Septibranchia).

8) Die in jüngerer Zeit bestätigten Befunde, dasz die Fangarme der ‘Cephalopoden rein

cerebral-innervierte Organe darstellen geben der Bezeichnung Siphonopoda für die Klasse

den Vorzug. Die verschiedenen, frühen Entwicklungslinien fossiler Siphonopoden werden als
eine Unterklasse Orthoceroida zusammengefasst und so den Nautiloida, Coleoida und

Ammonoida gegenübergestellt.

Einige weitere Taxa und Gruppenbezeichnungen werden diskutiert, wie darauf hingewiesen

wird, eine vergleichend nicht gerechtfertigte Hypertrophie systematischer Gruppen zu

vermeiden.

9

_—

MALACOLOGIA, 1980, 19(2): 279-288

CHROMATOPHORE ARRANGEMENTS OF HATCHLING LOLIGINID SQUIDS
(CEPHALOPODA, MYOPSIDA)

Deirdre A. McConathy, Roger T. Hanlon, and Raymond F. Hixon

The Marine Biomedical Institute, 200 University Boulevard,
Galveston, Texas 77550, U.S.A.

ABSTRACT

The color, location and number of chromatophores were studied as a basis for identifying
hatchlings of three western Atlantic loliginid squids (Loligo plei, Loligo pealei and Lolliguncula
brevis) and one eastern Pacific species (Loligo opalescens). Counts of chromatophores were
made on the head and mantle of the squid hatchling, and the mean number and frequency
distribution were calculated to establish a standard number of chromatophores for each area.
Lines drawn to connect specific groups of chromatophores formed rows and shapes that were
used to describe a specific arrangement for each species. Comparisons among the species
indicate that all four are distinguishable by their characteristic chromatophore arrangements at
hatching. Loligo opalescens and Lolliguncula brevis are the most easily identifiable species,
while Loiigo plei and Loligo pealei are more difficult to distinguish.

INTRODUCTION

Neritic squids of the family Loliginidae are
increasingly important worldwide as neuro-
physiological research models (Rosenberg,
1973; Arnold et al., 1974; Matsumoto, 1976)
and as commercial fisheries resources (Voss,
1973; Okutani, 1977; Rathjen et al., 1979).
While this importance has resulted in a better
understanding of the biology of some loliginid
species, most studies have been concerned
with adult animals; relatively little is known
about the hatchlings. In particular, little infor-
mation exists on the distinguishing character-
istics of the hatchlings. Historically, chromato-
phore coloration and patterning in cephalo-
pods have not been used as a means of iden-
tification because the delicate skin is easily
abraded during capture and colors fade in
preservation. However, recent works (e.g.
Holmes, 1940; Wolterding, 1971; Packard &
Hochberg, 1977; Hanlon, 1978; Hanlon &
Hixon, in press) have shown that skin pattern-
ing is species-specific in several cephalopods
and is useful in the identification of live ani-
mals. While some workers (Joubin, 1892;
Naef, 1921-1928) have suggested the impor-
tance of chromatophores for the identification
of hatchlings, only Fioroni (1965) and Hall
(1970) have attempted species-specific de-
scriptions of chromatophores of hatchlings.

We believe that chromatophores, one of the
basic elements of cephalopod skin patterning

(as defined by Packard & Hochberg, 1977),
provide a basis for identification of squid
hatchlings. In this paper we describe and
compare four New World species: the tropical
arrow squid Loligo (Doryteuthis) plei Blain-
ville, 1823, the common squid Loligo pealei
Lesueur, 1821 and the brief squid Lolliguncula
brevis (Blainville, 1823), all from the western
Atlantic; and the California market squid
Loligo opalescens Berry, 1911 from the
eastern Pacific. Other noteworthy references
that describe or illustrate chromatophores of
late embryonic or post-hatching stages of
these species are: Loligo plei (LaRoe, 1967:
176); Loligo pealei (Brooks, 1880: pl. 3, fig. 18;
Verrill, 1881: 320 and pl. XLI; Arnold,
1965: 31; 1971: 277); Lolliguncula brevis
(LaRoe, 1967: 186; Hall, 1970: 746, 766; and
Hunter & Simon, 1975: 50, fig. 15); Loligo
opalescens (Berry, 1912: 297 and pl. XLIII;
Fields, 1965: 60; Okutani & McGowan, 1969:
11). Because the primary interest of these
studies was either morphological or embry-
ological and not specifically about chromato-
phores, the chromatophore arrangements
depicted may be inexact.

Collectively the three western Atlantic spe-
cies range from Nova Scotia (45°N latitude)
southward throughout the Gulf of Mexico and
Caribbean Sea to Argentina (45°S); Loligo
opalescens ranges from British Columbia in
the eastern Pacific (50°N) to the tip of Baja
California (22°N). These myopsid squids live

(279)

280 MCCONATHY, HANLON AND HIXON

on the continental shelf from the shore to
depths greater than 200 m. They all have
relatively small telolecithal eggs, are of a
similar small size at hatching and become
planktonic after hatching.

Because the generic status of Loligo plei is
uncertain we use Doryteuthis as a subgeneric
designation (see discussion in Cohen, 1976).
To avoid confusion in the text the abbreviation
L. is used only for the three species of the
genus Loligo. In all references to Lolliguncula
the genus is given in full.

MATERIALS AND METHODS

Wild-caught adult L. plei, L. pealei and
Lolliguncula brevis captured by dipnets and
bottom trawls in the northern Gulf of Mexico
south of Galveston, Texas were maintained
separately by species in circular, 2m diam-
eter, 1000 I closed-system seawater tanks
(Hanlon et al., 1978). Mating and egg laying
were observed in captivity thus insuring posi-
tive identification of each species of hatchling.
Egg mops were removed from the oyster shell
substrate and segregated into 64 | rectangu-
lar aquaria within the original 1000 | tank (for
details see Hanlon et al., 1979). Development
occurred at 21 to 23°C for these species with
salinities ranging from 32°/ to 37°/ for the
two Atlantic Loligo species and 22.5°/a to
24°/со for Lolliguncula brevis. L. opalescens
eggs were collected by divers in Monterey
Bay, California and shipped to Galveston in
insulated, sealed plastic bags filled with oxy-
gen and seawater at a temperature of 12.5°C
and a salinity of 36°/ю. These eggs were
hatched in the 10001! tanks at 15°C and a
Salinity of 367/00.

Live hatchlings zero to five days posthatch-
ing were randomly chosen and transferred by
pipette to small petri dishes where they were
examined under a stereomicroscope at 50x.
Excess water was removed to restrict move-
ment of hatchlings. Both dorsal and ventral
surfaces were observed by carefully manipu-
lating the squids with surgical forceps. A rep-
resentative drawing was made of each spe-
cies at 25x with the aid of a camera lucida.
The color and placement of each chromato-
phore for twenty individual hatchlings were
plotted on this outline. The results described
here are based on squids from the same
brood, but additional observations of photo-
graphs and live hatchlings from other broods
supplemented the descriptions of the twenty
specific individuals.

The color of an individual chromatophore
varies according to the degree of expansion.
Retracted or slightly expanded chromato-
phores appear as prominent “dots” on a
squid hatchling and are darker in color and
more discrete than expanded chromato-
phores. Since chromatophores of hatchlings
are most commonly retracted or only slightly
expanded, our descriptions and drawings are
based on chromatophores in this state. Colors
were standardized according to A Dictionary
of Color (Maerz & Paul, 1950). Chromato-
phores of hatchlings may be broadly divided
into two categories of color: reds, ranging
from Flaming maple (Maerz 8 Paul, 1950: pl.
4, no. L-5) to Domingo brown (ibid.: pl. 8, no.
L-9); and yellows, ranging from Lemon yellow
(ibid.: pl. 10, no. K-3) to Caramel (ibid.: pl. 12,
no. F-10). Standards of color are assigned for
each species, but due to intraspecific variabil-
ity of color these standards should not be
considered definitive. A considerable inter-
specific overlap of color occurs; therefore,
color alone is not used as a distinguishing
character. For these reasons, and for brevity,
we refer only to a generalized classification of
chromatophores as red or yellow. Further-
more, it is understood that in the text the
words red or yellow refer to a single chroma-
tophore of that color and not to the total hue of
the animal.

A model arrangement of chromatophores
was derived for each species. A standard
number of chromatophores in a given ana-
tomical area was determined on the basis of
the mean number of chromatophores and
their frequency distribution. Descriptions of
arrangements of chromatophores are based,
in part, on lines drawn to connect chromato-
phores that create geometric shapes and
rows. Although this organization is arbitrary, it
establishes order and defines some of the
most stable and distinct elements of the ar-
rangement of chromatophores.

The following sequence for collection of
data was used for each region of the hatch-
ling, and color, placement and numbers of
chromatophores were recorded: (1) Dorsal
head, (2) Dorsal mantle, (3) Ventral head, (4)
Ventral mantle, (5) Total number of chroma-
tophores and (6) Dorsal mantle length (ML;
measured from anterior margin to posterior tip
of mantle, calculated at 25x).

The red chromatophores of the ventral
mantle were categorized according to the ar-
rangements defined by Fioroni (1965): irregu-
lar (chromatophores not ordered in rows in
any direction), transverse rows, longitudinal

SQUID HATCHLING CHROMATOPHORE ARRANGEMENTS 281

rows and regular (chromatophores both in
transverse and longitudinal rows that, when
joined by lines, form a grid). If rows occurred
their number was recorded.

Observations of the hatchlings were made
in an anterior to posterior direction assuring
consistent technique. This procedure is es-
pecially helpful for species in which trans-
verse rows occur on the ventral mantle, since
the first three rows generally are the straight-
est and easiest to “read”; additional rows
often are less clear-cut and may require arbi-
trary decisions concerning individual place-
ment.

For statistical analyses, a nonparametric
Kruskal-Wallis test was used to establish dif-
ferences among the four species for selected
single classification parameters. The sum of
Squares simultaneous test procedure (STP)
was then used to compare these differences
at a .01 levei of significance (Sokal & Rohlf,
1969: 387).

RESULTS

Descriptions of arrangements of chroma-
tophores: The drawings in Fig. 1 show the
dorsal and ventral model arrangement of
chromatophores for each species. The stand-
ard numbers (and ranges) of chromatophores
for each species used in these descriptions
are compiled in Tabie 1. Fig. 2 is a photo-
graph of a live hatch!ing to compiement Fig. 1.

Loligo plei: L. plei has a standard number
of 82 chromatophores of which 16 are dorsal
and 66 ventral (Fig. 1A). Red chromatophores
appear Cardinal (Maerz & Paul, 1950: pl. 5,
no. L-5) and yellows are Chrome oP (ibid.: pl.
10, no. K-12). Mean mantle length of L. plei at
hatching is 1.5 mm.

Nine yellow chromatophores occur on the
dorsal surface of the head and five on the
mantle. The five anteriormost chromato-
phores on the head form an inverted “V” be-
tween the eyes, with the apex at the base of
the first pair of arms. The four remaining
chromatophores on the head occur in a trans-
verse curved row at the posterior end of the
head. The five yellow chromatophores on the
dorsal mantle form a pentagon when joined
by lines, with its apex located posteriorly be-
tween the fins. Two red chromatophores are
centered dorsally within the pentagon on each
side of the ink sac.

Ventrally there are 31 chromatophores on

the head and 35 on the mantle. The ventral
surface of each tentacle has five chromato-
phores arranged in a row, alternating red (3)
and yellow (2). Each fourth arm has two red
chromatophores. A transverse row of three
yellow chromatophores runs between the
base of the fourth pair of arms and the eyes.
Directly between the eyes is a pair of red
chromatophores, and posteror to each eye is
a pair of yellow chromatophores. Four red
chromatophores form a trapezium on each
side of the posterior end of the head when
connected by lines. Twenty red chromato-
phores are arranged in five transverse rows
on the ventral mantle. Yellow chromatophores
are located in three areas: short rows of three
posterior and lateral to row 1, intermixed with
row 3, and one at each end of rows 4 and 5.

Loligo pealei: Of the standard 97 total
chromatophores 19 are dorsal and 78 are
ventral (Fig. 1B). Red (Cardinal) and yellow
(Chrome OP) chromatophores are the same
color as those of L. plei. Mean mantle length
of L. pealei is 1.6 mm at hatching. Nine chro-
matophores appear on the dorsal surface of
the head and ten on the dorsal mantle. Those
on the head occur in an inverted “V” and a
transverse row similar to L. plei. The eight
yellow chromatophores on the dorsal mantle
form a tear-drop shape when connected by
lines, with two red chromatophores on the
mantle centrally located on each side of the
ink sac.

The arrangement on the ventral surface of
the head consists of alternating red (3) and
yellow (3) chromatophores on the tentacles,
two red chromatophores on each fourth arm
and a transverse row of three yellow chroma-
tophores at the base of the fourth pair of arms.
The arrangement is completed with two red
chromatophores between the eyes, a pair of
yellow chromatophores posterior to each eye,
and a trapezium formed by four red chroma-
tophores on each side of the base of the
head. This arrangement is identical to L. plei
with the exception of an extra yellow chroma-
tophore at the tip of each tentacle. The ventral
surface of the mantle has 27 red chromato-
phores assembled in six transverse rows.
Eighteen yellow chromatophores on the man-
tle occur in association with rows 1, 3, 5 and 6
in locations similar to those described for L.
plei.

Lolliguncula brevis: Lolliguncula brevis has
a standard number of 93 chromatophores (12
dorsal and 81 ventral) (Fig. 1C; Fig. 2). Red
chromatophores appear Brazil brown (Maerz

McCONATHY, HANLON AND HIXON

282

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SQUID HATCHLING CHROMATOPHORE ARRANGEMENTS 283

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FIG.1. Diagrammatic drawings of the mode: arrangements of chromatophores of four species of loliginid
squid hatchlings. A) Loligo plei, B) Loligo peaiei, C) Lolliguncula brevis and D) Loligo opalescens. Dorsal
view on left, ventral view on right for A, B, C; dorsal view on top and ventral view on bottom for D. All drawn to
same scale. Retracted red chromatophores represented by e, retracted yellow chromatophores by o. Solid
lines connecting individual chromatophores are explained in the text.

284 McCONATHY. HANLON AND HIXON

FIG. 2. Ventral view of a live Lolliguncula brevis hatchling. EB—eye ball, RC—red chromatophore, St—
statolith, YC—yellow chromatophore, IS—ink sac, I—iridophore.

& Paul, 1950: pl. 8, no. L-8) and yellows ap-
pear Burnt-orange (ibid.: pl. 3, no. E-12).
Lolliguncula brevis has a mean mantle length
of 1.8 mm at hatching.

No red chromatophores occur dorsally, but
nine yellow chromatophores are on the head
and three on the mantle. The dorsal chroma-
tophores on the head occur in an inverted “V”
and a transverse row as described for L plei
and L. pealei. The three yellow chromato-
phores at the posterior end of the mantle de-
scribe a triangle when connected by lines.

The 31 chromatophores on the ventral
head are positioned as follows: on the tenta-
cles in alternating rows of red (3) and yellow
(3), a pair of reds on each fourth arm, a row of
three yellows posterior to the fourth pair of
arms, a pair of reds between the eyes and a

pair of yellows posterior to each eye. Three
red chromatophores on each side of the pos-
terior end of the head form a triangle. The 39
red chromatophores on the ventral mantle are
arranged in seven transverse rows. Yellow
chromatophores are located in three areas: in
pairs laterally at each end of row 1, just ante-
rior to and intermixed with row 4 and individ-
ually at each end of row 6.

Loligo opalescens: This species has a
standard number of 100 chromatophores (26
dorsal and 74 ventral) (Fig. 1D). The red
(Brazil brown) and yellow (Burnt-orange)
chromatophores are similar in color to those
of Lolliguncula brevis. Mean mantle length at
hatching is 2.7 mm.

The arrangement of the ten chromato-
phores on the dorsal head is best described by

SQUID HATCHLING CHROMATOPHORE ARRANGEMENTS 285

six prominent red chromatophores that form a
hexagon, within which a single yellow chro-
matophoreiscentered. Thereis a single yellow
chromatophore at the base of the first pair of
arms and two others positioned laterally at the
posterior base of the head. Of the 16 chroma-
tophores on the dorsal mantle, six are red and
ten are yellow. The six red chromatophores
form a longitudinally oriented elongate hexa-
gon. The ten yellow chromatophores are vari-
able in their positions but closely resemble the
arrangement diagrammed.

Ventraliy there are 34 chromatophores on
the head and 40 on the mantle. The ventral
surface of each tentacle usually has seven or
eight chromatophores alternating red and yel-
low. Many chromatophores are located in po-
sitions similar to those described for the other
three species: two red chromatophores on
each fourth arm, the transverse row of three
yellow chromatophores posterior to the fourth
pair of arms, the pair of reds between the
eyes and the pair of yellows posterior to each
eye. Three red chromatohores at the posterior
end of the head form a triangle similar to
Lolliguncula brevis. The 34 red chromato-
phores on the ventral mantle are irregular in
arrangement. Both red and yellow chromato-
phores on the ventral mantle are variable in
their positions but most commonly resemble
the arrangement in Fig. 1.

Comparison of the four species. Dorsal
arrangement of chromatophores: The ar-
rangement and color of chromatophores on
the head are identical for L. plei, L. pealei and
Lolliguncula brevis. L. opalescens is differen-
tiated by a hexagon of red chromatophores
surrounding a yellow chromatophore. These
comparisons are particularly consistent be-
cause the dorsal surface of the head of each
species is the area of least variability.

L. opalescens can be separated from the
other three species by the greater number of
both yellow and red chromatophores on its
dorsal mantle. It has six reds, as opposed to
two in L. plei and L. pealei and none in Lolli-
guncula brevis. L. plei and L. pealei are not
readily distinguishable because they have a
similar arrangement and number of chroma-
tophores that overlap somewhat due to the
variability of occurrence of individual chroma-
tophores. Lolliguncula brevis may be sepa-
rated from the rest since it has no red chroma-
tophores on its dorsal mantle and only three
yellow chromatophores. Twenty percent of
the L. plei hatchlings had only three yellows in

the same arrangement as Lolliguncula brevis,
but L. plei always had two red chromato-
phores on the dorsal mantle.

Ventral arrangement of chromatophores:
The ventral head is relatively stable in ar-
rangement for all four species except at the tip
of the tentacles and the posterior base of the
head.The occasional addition of a single red
chromatophore at the base of the head will
change the triangular shape described for
Lolliguncula brevis and L. opalescens to the
trapeziform shape described for L. plei and L.
pealei. Conversely the rare deletion of a red
chromatophore from the trapezium described
for L. plei and L. pealei creates the triangle
shape associated with Lolliguncula brevis
and L. opalescens. Therefore this area alone
is not reliable as an indicator of species
identity.

The ventral mantle has the greatest number
of chromatophores in all four species and
their arrangement is complex. Distinctions
can be made by comparing the arrangement
of chromatophores, number of transverse
rows created by red chromatophores and the
total number of red chromatophores. Lolli-
guncula brevis has the largest total number of
reds. They are arranged in seven transverse
rows that easily differentiates this species
from the other three. L. plei and L. pealei are
the most similar in arrangement but usually
differ in the number of transverse rows (5
versus 6, respectively) and the sum of red
chromatophores (20 versus 27, respectively).
L. opalescens is best identified by an irregular
arrangement of red chromatophores on the
ventral mantle. Statistical comparisons of the
total number of red chromatophores on the
ventral mantle indicate that the four species
are different at a .01 significance level. How-
ever, the ranges for numbers of red chroma-
tophores on the ventral mantle given in Table
1 show the possibility of overlap between L.
plei and L. pealei, and between Lolliguncula
brevis and L. opalescens. Yellow chromato-
phores on the ventral mantle are similar in
location and number in L. plei, L. pealei and
Lolliguncula brevis; L. opalescens is differ-
ent, having only six yellows that occur in rela-
tively random locations.

Total number of chromatophores: L. plei
has the fewest chromatophores and can be
separated from the others at the .01 signifi-
cance level; however, a rare possibility of
overlap between the upper limit of L. plei (88)
and the lower limit of L. pealei (88) does ex-
ist. Although Lolliguncula brevis and L.

286 MCCONATHY, HANLON AND HIXON

opalescens have a statistically different total
number of chromatophores, sufficient overlap
occurs to reduce the usefulness of this char-
acter. Comparisons of L. pealei with Lolli-
guncula brevis and L. opalescens show no
statistical differences; the total number of
chromatophores of L. pealei is within the
range of either of those species.

Mantle length: L. opalescens has a sub-
stantially greater mantle length (mean ML
2.7 mm) at hatching that distinguishes it from
Lolliguncula brevis (1.8 тт), L. pealei
(1.6 mm) and L. plei (1.5 mm); these differ-
ences are statistically significant at the .01
level. Although there is a statistically signifi-
cant difference between Lolliguncula brevis
and L. pealei or L. plei, overlap does occur.
Mantle length is a distinguishing character
only at hatching because at present growth
rates and methods of determining age (e.g.
from growth rings of statoliths) are not known
for these species.

Summary: All four species are distinguish-
able by their characteristic arrangement of
chromatophores. [. opalescens and Lolli-
guncula brevis are the most easily identifiable
species while L. plei and L. pealei are the
most similar.

L. opalescens is immediately recognized at
hatching by its greater mantle length. This
species differs from the other three by its
greater total number of dorsal chromato-
phores, in particular the twelve dorsal red chro-
matophores. The irregular arrangement of the
red chromatophores on the ventral mantle is
peculiar to this species.

Lolliguncula brevis contrasts with the other
three species by having no red chromato-
phores on the dorsal mantle and only three
yellows. Both the greater number of trans-
verse rows (7) and larger total number of red
chromatophores on the ventral mantle distin-
guish this species. The mantle length of
Lolliguncula brevis, less than L. opalescens
but greater than L. pealei and L. plei, is also a
good indicator.

L. pealei can be differentiated from L. plei
on the basis of three additional yellow chro-
matophores on its dorsal mantle. L. pealei has
six transverse rows in the ventral arrangment
of the mantle chromatophores while five rows
occur in L. plei. L. plei also may be singled out
by its lower total numbers of chromatophores.

DISCUSSION

When Fioroni (1965) explored the use of
chromatophores as a taxonomic character for

the hatchlings of several Mediterranean
cephalopods, he described the chromato-
phores of Naef's (1921-1928) late embryonic
stages. Fioroni’s (1965) descriptions of hatch-
lings at Stage XX and older were based on
color, location and number of chromato-
phores and indicated substantial variability
among the three characters. But while he ob-
served that “individual variations occur so that
only practically two or three completely identi-
cal embryos can be found” (our translation),
he also stressed that the more constant ele-
ments may provide a characteristic arrange-
ment. Our study provides such a model for
four New World loliginid species, as well as
the methodology for determining character-
istic arrangements for related species.

Application of this technique may ultimately
lead to a key for live squid hatchlings. Already
comparisons can be made. Fioroni's (1965)
assumption, based on descriptions by Brooks
(1880), Verrill (1881) and Berry (1912), that L.
opalescens and L. pealei had significantly
fewer chromatophores than L. vulgaris, is
verified by our findings that L. opalescens and
L. pealei hatchlings have 100 and 97 chroma-
tophores, respectively, while L. vulgaris has
200. Such a key used in conjunction with
morphometric indices would be most instruc-
tive in the field of cephalopod taxonomy,
which suffers from a lack of study of compara-
tive anatomy and development on the vast
majority of species (Voss, 1977). It may also
help to establish phylogenetic affinities within
the family Loliginidae. For instance, our find-
ings suggest that L. plei and L. pealei may be
more closely related to each other than to the
other two species examined.

The eventual taxonomic differentiation of
young squids would also benefit squid fisher-
ies research. Most adult loliginids are school-
ing animals, and this contagious or clumped
spatial distribution (Cassie, 1971) makes esti-
mates of actual abundance difficult. Estimates
based on the more randomly distributed
young stages soon after hatching could be
more accurate.

In general the significance of patterning in
hatchling cephalopods is poorly understood.
The relationships of body patterning and be-
havior in cephalopods have only recently
been investigated, and these studies cover only
a few genera such as Octopus (Packard &
Sanders, 1971; Wolterding, 1971; Warren et
al., 1974; Packard & Hochberg, 1977), Sepia
(Holmes, 1940), Loligo (Hanlon, 1978) and
Sepioteuthis (LaRoe, 1971; Moynihan, 1975).
The only true body patterns that young Loligo

SQUID HATCHLING CHROMATOPHORE ARRANGEMENTS 287

or Lolliguncula are known to be capable of
are “Clear” and “All Dark” (Hanlon, 1978). In
“Clear” the chromatophores are retracted
and the animal is translucent. The irido-
phores, which are located beneath the chro-
matophores and reflect blue and green
wavelengths of light, are also elements of
patterning. The scattered iridophores on the
mantle of hatchlings may or may not be con-
spicuous depending on the angle and amount
of light reflected; but the iridophores that
densely cover the eye balls and ink sac are
always prominent and render these organs
opaque or iridescent. Therefore, the eye balls
and ink sac act as patterning components in
the “clear” pattern, as suggested by Fioroni
(1965) and Packard & Sanders (1969). In the
“all dark” pattern all chromatophores are ex-
panded, and since there are more chromato-
phores ventrally, a ventro-dorsal gradient of
color is present. This is a curious phenom-
enon since most pelagic marine animals are
darker on the dorsal surface and lighter under-
neath for countershading. The significance of
the ventro-dorsal shading gradient is un-
known. Field observations of hatchlings and
information on their habitat and mode of life
during the first few weeks may clarify the
significance of the higher number of chroma-
tophores present ventrally. However, it is
known that the hatchlings do not swim upside
down as was stated by Fioroni (1965). In the
course of growth and the subsequent addition
of chromatophores the gradient becomes
dorso-ventral. In small L. plei (30 mm ML) the
squid is already capable of several chromatic
components. Thus, knowledge of the exact
placement of chromatophores at hatching
may provide baseline information to study the
growth of chromatophores and the ontogeny
of patterning.

ACKNOWLEDGEMENTS

We were fortunate to have Drs. Gilbert L.
Voss and Sigurd von Boletzky review the
manuscript and thank them for their helpful
comments. This work was supported in part
by Grant No. RR 01024-03 from the Division
of Research Resources, National Institutes of
Health and the Marine Medicine General
Budget account 7-11500-765111 of the Ma-
rine Biomedical Institute, University of Texas
Medical Branch, Galveston, Texas. We also
thank Vicki Chandler and Sharon Burton for
typing and proof reading the many drafts
necessary to complete the manuscript.

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MALACOLOGIA, 1980, 19(2): 289-296

LOCOMOTION RATES AND SHELL FORM IN THE GASTROPODA:
À RE-EVALUATION

A. Richard Palmer!

Department of Zoology NJ-15, University of Washington, Seattle, Washington 98195, U.S.A.

ABSTRACT

A reconsideration of data from Linsley (1978a) indicates that the association between crawling
speed and shell form is not likely to be a causal one. The correlation between speed and form is
due largely to multiple adaptations to different habitats (particulate versus rocky substrates). п
addition, a conservative estimate of the energy saved by reducing drag experienced at crawling
speeds is shown to be more than three orders of magnitude less than the energy expended
during normal activity. One may be able to distinguish surface dwelling from burrowing gastro-
pods in the fossil record based on shell form, but not “fast” from “slow” moving species.

INTRODUCTION

Linsley (1978a,b) has recently advanced
the proposition that shell form in marine gas-
tropods may be related to rates of locomotion,
finding that more rapidly moving animals have
subjectively lower drag shells than slower
moving ones in general. The purpose of this
paper is to examine some alternative hypoth-
eses accompanied by additional data which
suggest this correlated association is not a
Causal one, but is very likely a consequence
of other covarying biological and environ-
mental factors.

The additional information | have compiled
(Table 1) falls into three categories: 1) type of
locomotion (muscular waves of various types
versus Cilia); 2) habitat type (predominantly
sand versus rock); and 3) some estimates of
the actual drag forces experienced by snails
at crawling speeds in relation to their tenacity.
| present this information only for the species
that Linsley (1978a) has considered, and
while much more extensive data exist on the
rates of locomotion for many prosobranch
species (Miller, 1972, 1974a) the general
conclusions adequately obtain from his
smaller sample.

PROCEDURES AND RESULTS

In Table 1, | have arrayed species in the
five ‘form rank’ categories of Linsley (1978a)
where increasing rank relates to presumed

increases in drag experienced by the shells.
This is a compound subjective ranking based
on some measure of bilateral symmetry (pre-
sumably symmetry with respect to the direc-
tion of motion rather than with respect to the
axis of coiling, though this is not clear in his
description of methods) and on the amount of
shell ornamentation, where both greater
asymmetry and more extensive sculpture are
believed to increase drag. Species followed
by an 'M' carry their shell at least partially
covered either by the mantle or foot during
locomotion.

Locomotor types have all been identified
from the appendix of Miller (1974b). For spe-
cies not listed in this appendix, | have as-
signed the mode of locomotion determined
either for other members of the same genus
or the same family. Such inferences are indi-
cated by the subperscripts G and F respec-
tively in column 2 of Table 1. The details of the
different locomotor types are illustrated and
discussed in Miller (1974b).

The habitat information is unfortunately
crude but | think sufficient for the distinctions |
would like to make. It has been collected from
several sources identified by the footnotes at
the top of each column (columns 3-7, Table
1). The column headed ‘summary’ (column 8)
indicates what is considered to be the “aver-
age” or "typical” habitat of the species based
on these varied sources and it is this habitat
assignment to which | refer in subsequent
discussion. As with locomotory modes, a G or
F superscript indicates an inference from

Present address: Department of Zoology, University of Alberta, Edmonton, Alberta, Canada T6G 2E9.

(289)

PALMER

290

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292 PALMER

species in the same genus or family respec-
tively.

Drag has been estimated using the follow-
ing equation (Alexander, 1968, eq. 28):

Drag = V2 M?AC,

where r refers to the fluid density (essentially
1 gm/cm? for seawater); v is the velocity of
the object relative to the fluid (for these com-
putations, crawling speeds from Linsley,
1978a); A is the measure of the area of the
object [| have used frontal area, the projected
area in the direction of motion, which for this
analysis may be approximated as a circle
whose diameter corresponds to the diameter
of the body whorl (column D under shell
size)]; and Cy is a drag coefficient whose
numerical value has been determined from
the empirical relation between Су and
Reynolds number (Tietjens, 1934, fig. 54) as-
suming the object to be a sphere of diameter
L (the approximate length of the adult shell).
This obviously unrealistic assumption of
spherical snails introduces some error, but
comparison of the C4/ Reynolds number rela-
tionship for spheres and cephalopod shells
(Chamberlain & Westermann, 1976, fig. 4) in-
dicates that this error is probably slight. The
crawling speeds are those measured by
Linsley (1978a). Approximate adult shell
sizes, both lengths (L) and diameters (D)
were compiled from Abbott (1974) using the
mean of the range of sizes given in the spe-
cies’ description. R¿ values are Reynolds
numbers, assuming a kinematic viscosity of
0.010 cm?/s for seawater, which were com-
puted for shells using adult length and crawl-
ing speed. The drag values thus provide a
rough approximation of the force required to
push a shell of a given size through the water
at crawling speeds and do not include any
frictional resistance between the sole of the
foot and the substrate.

Finally, tenacities (force required to dis-
lodge an attached animal) as measured nor-
mal to the substrate have been compiled from
Miller (1972) for comparison with the drag
forces. Her tenacity values in gm/cm? of foot
area have been converted to dyns through
multiplication by the foot area and gravitation-
al constant and are expressed as dyn x 10°.

Table 2 summarizes the information in
Table 1 for locomotor types and habitat. In
addition to the correlation between shell form
and speed noted by Linsley (1978a) there are
also strong associations between shell form
and 1) the manner in which the mantle and/or
foot covers the shell; 2) whether the species
use ciliary locomotion or muscular waves and
3) whether species live in a sand environment
or in the rocky intertidal. Nearly two-thirds of
the species of form rank 2 (presumed low
drag shells) envelop their shell with either the
mantle or the foot while moving so that the
shell itself is not responsible for drag, yet no
species in the higher drag categories (4-6)
exhibit this behavior. Approximately half of the
species of form ranks 2 and 3 utilize ciliary
locomotion whereas nearly all the species of
ranks 4 through 6 (presumed high drag shells)
use muscular waves. Finally, two-thirds to
three-quarters of the species with presumed
low drag shells (ranks 2 and 3) are sand
dwellers and none live in the rocky intertidal.
Rocky intertidal dwellers are restricted to
categories 4 and 5. Category 6 contains spe-
cies from only one genus associated with
rocky substrates and seagrasses.

Table 1 also tabulates the estimated drag
forces experienced by the various species
while moving through the water and it is clear
by comparing these with what information is
available on tenacities (Miller, 1574b) that the
estimated drag forces at the speeds gastro-
pods move is three to six orders of magnitude
less than the force required to dislodge an

TABLE 2. Proportions of species of different locomotor types and from different habitats as a function of form

ranking.
Locomotion type Habitat

Form Enveloping Muscular Rocky

Rank N mantle Ciliary waves Sand intertidal Other
2 18 0.61 0.56 0.44 0.67 0.0 0.33
31 5 0.20 0.40 0.60 0.80 0.0 0.20
4 15 0.0 0.07 0.93 0.0 0.472 0.54
5 5 0.0 0.25 0.75 0.20 0.40 0.40
6 3 0.0 0.0 1.0 0.0 0.0 1.0

INot including Turbinella angulata for which information is not available.
Includes Littorina angulifera, living intertidally on mangrove roots.

GASTROPOD LOCOMOTION AND SHELL FORM 293

animal while moving. Note that this is assum-
ing no movement of water relative to the shell
except that due to locomotion, i.e. no wave
action or tidal current.

DISCUSSION AND RE-EVALUATION

Linsley’s proposition (1978a) that drag re-
ducing morphologies in marine gastropods
may have evolved in response to higher lo-
comotion rates derives from a correlation be-
tween average crawling speeds and a ranking
of shell form based on presumed drag resist-
ance. Considering the above results, it would
appear that this correlation is due largely to a
more complicated association of several other
biologically or ecologically important factors.
First, ciliary locomotion is on the order of two
to three times faster than either retrograde
monotaxic or retrograde ditaxic and nearly
three times faster than arhythmic muscular
waves on the average (Miller, 1974a, table 1).
This is particularly true for smaller gastropods
(less than 15mm). If one only compares
Crawling speeds of Conus species, the mean
speed of species using ciliary locomotion
(1.56 mm/s, N = 5) is more than three times
that of species using some form of muscular
waves (0.43 mm/s, N = 13; Miller, 1972) and
this difference is highly significant
(P < 0.001, Mann-Whitney U test). Hence,
the faster average speeds observed among
species in form categories 2 and 3 are due at
least in part to differences in locomotion
modes. This does not affect the interpretation
of the correlation between speed and form, it
only provides a partial explanation for the dif-
ferences in mean speed observed among the
different form categories.

Second, species using ciliary locomotion
are mostly sand dwellers (10 of 14, Table 1;
30 of 34 species identified in Miller, 1974a in
her table 2). In fact, Miller (1974a: 146) states
that “Ciliary and discontinuous locomotion in
prosobranchs appear to be primarily adapta-
tions to soft substrata.” In addition, gastropod
crawling speeds for ciliary locomotion are 1.5
to 2 times faster on Plexiglas than on sand
(Miller 1974a: table 3). Thus crawling speeds
of ciliary movers measured on Plexiglas will
most likely be faster than those the animals
experience in their natural environment, and
this artifact may also contribute to the mean
speed differences among form categories.

Third, species living in sandy environments
spend at least some time burrowing in the
sediment. This is true for Busycon (Paine,

1963), Cassis (Hughes & Hughes, 1971),
Fasciolaria (Snyder 8 Snyder, 1971),
Melongena (Hathaway 8 Woodburn, 1961),
Polinices (Edwards & Huebner, 1977), and
Oliva (Marcus & Marcus, 1959). The energy
expended while burrowing has been meas-
ured at nearly 10 times that while crawling on
the surface in a sand dwelling nassariid,
Bullia (Trueman & Brown, 1976) presumably
largely as a result of the increased resistance
experienced while moving through sand.
Consequently one would expect species that
burrow to possess less sculpture and present
a smaller cross-sectional area in the direction
of movement than those species that do not
burrow. This should be particularly true for
shell sculpture since the markedly higher
viscosity and lower crawling speeds in a
sand/water “solution” will result in a lower
Reynolds number and thus a relatively
greater contribution of surface friction to over-
all drag. Given that two-thirds to three-
quarters of the species in rank categories 2
and 3 are sand dwellers (Table 2) it is not
surprising that they exhibit such lower drag
shells. Much of the variation in drag reducing
morphology between the form rank categories
can thus be attributed to habitat constraints
rather than crawling speed. Hence, because
drag reducing morphologies and ciliary loco-
motion are both associated with a sandy en-
vironment where burrowing efficiency may be
an important selective force, the association
between surface crawling speed and shell
form appears due in large part to the co-
evolution of multiple adaptations for inhabiting
particulate substrates and not because of a
direct response of shell form to open surface
Crawling speed per se.

Another habitat dependent factor is shell
sculpture. Open surface (e.g. rocky intertidal)
dwelling gastropods may be more exposed to
shell crushing predation particularly by fishes
than sand dwelling species. This is supported
to some extent by Vermeijs observation
(1978: 131) that while “the most profound
interoceanic variations in architecture occur
on open rocky surfaces,” changes in sand
dwelling species are considerably less pro-
nounced. Consequently, sculptural defenses
against crushing (Vermeij, 1978; Palmer,
1979) may be of greater importance to open-
surface dwelling gastropods. Such a relative
advantage of shell sculpture in open surface
dwelling species compared to sand dwellers
would be further augmented by its tendency
to increase the drag experienced while bur-
rowing among sand dwellers. The restriction

294 PALMER

of rocky intertidal species to rank categories 4
and 5 (Table 2) is due largely to a greater
development of shell sculpture.

Further complicating the interpretation of
hydrodynamic drag with respect to shell
sculpture are conflicting observations of intra-
specific variation related to wave action. The
degree of sculptural development has been
found both to increase (James, 1968; Sakai,
1972) and decrease (Struhsaker, 1968) intra-
specifically in different species of Littorina in
response to increasing wave action. At certain
water velocities, sculpture may actually de-
crease drag (Chamberlain & Westermann,
1976). Thus, sculpture per se cannot always
be assumed to increase the hydrodynamic
drag experienced by surface dwelling gastro-
pods.

Finally, and perhaps most importantly for a
streamlining argument, is the consideraton of
water velocities experienced by gastropods
independent of their movement. Koehl (1977)
has measured water velocities of up to
160 mm/s in tidal currents and 1300 mm/s in
wave surge. These are 2 to 3 orders of magni-
tude greater than gastraopod crawling
speeds. Given that environmental water ve-
locities are so much greater than crawling
speeds, the marginal increase in water veloc-
ity relative to the shell due to locomotion
would seem to be insignificant. Further, if
water velocity is such an important factor in-
fluencing shell form, one would predict that
open surface dwelling species should exhibit
low drag shells, and the data in Table 2 do not
support this prediction. Rocky intertidal spe-
cies are restricted to form categories 4 and 5
(presumed high drag shells) while species liv-
ing in rubble or under rocks generally occur in
all categories.

To place the drag experienced by snails at
crawling speeds in perspective, it is informa-
tive to estimate the energy expended to over-
come this drag and compare it to values for
locomotory metabolism. A single example il-
lustrates the point. From Table 1, the esti-
mated drag on Thais rustica at crawling speed
is 12.2 dyn (measured values for drag on an
unsculptured morph of Thais (=Nucella)
lamellosa of comparable size at a water ve-
locity of 2 mm/s are less than one tenth of
this; Palmer, unpublished). The power, or
energy per unit time to overcome this force,
equals the force times the crawling velocity,
yielding a value of 2.4 ergs/s (12.2 dyn x
0.2 cm/s). Oxygen consumption in a com-
parable sized Thais (=Nucella) lapillus during

“intermittent low activity” has been measured
at approximately 70 ul/hr (Bayne & Scullard,
1978) which converts to 3.9 x 103 ergs/s
(1.9 x 10-2 ul02/s) x (4.8 x 10-3 cals/
ul05) x (4.2 x 107 ergs/cal)]. The total ener-
gy expended to overcome drag is thus more
than three orders of magnitude less than that
expended during low levels of activity. Since
one is really interested in energy saved due to
relative differences in drag attributable to shell
orientation or sculpture rather than tota/ drag,
the energy saved will be even a smaller frac-
tion of the energy expended moving. Hence,
even though one might argue that reducing
drag at crawling speeds still represents an
energy savings, this savings will be vanish-
ingly small.

The preceding discussion has analyzed the
relation between crawling speed and drag re-
ducing morphologies without examining how
various shell features contribute to drag. As
already mentioned, certain kinds of shell
sculpture can reduce drag in rapidly moving
water though they may tend to increase drag
due to surface friction at lower water veloci-
ties (Chamberlain & Westermann, 1976).
However, shell shape will also affect drag,
particularly pressure drag (that drag due to
the momentum transferred by the moving
body to the fluid in the form of eddies and
turbulence in the wake). Species with low
apical half-angles [i.e. more elongate spires
like Fasciolaria tulipa (Linné)] should experi-
ence less pressure drag than those with high
apical half-angles [shorter spires like
Busycon contrarium (Conrad)] because more
gradually tapering trailing edges will tend to
reduce wake size (Alexander, 1968: 218).
Note that both of these species are consid-
ered presumed low drag shells (rank category
2). Caution should be exercised when trying
to assign complex forms such as marine
gastropod shells to categories based on
presumed differences in an equally complex
physical stress such as hydrodynamic drag.
In the absence of any empirical evidence,
such assignments must be considered highly
tentative.

CONCLUSIONS

Interpreting the adaptive value of gastropod
shell form based on single factor correlations
is risky for a variety of reasons, not the least of
which is that alternative causal factors may
account for the observed association. In such
correlative studies, the safest procedure is to

GASTROPOD LOCOMOTION AND SHELL FORM 295

identify as many plausible causal hypotheses
as possible and examine the degree to which
different hypotheses present different predic-
tions. Linsley (1978a,b) has examined the
hypothesis that locomotory rates may have
exerted an important influence on shell form.
His prediction that faster moving snails should
have lower drag shells is supported by a cor-
relation between shell characteristics be-
lieved to reduce drag, and increased crawling
speed. However, this association can just as
readily be explained as a compound adaptive
response to differences in habitat as | have
discussed above. If one compares non-sand
dwelling species whose shell is exposed to
the water during movement (i.e. whose shells
are not enveloped by the mantle or foot since
in these situations it is the mantle or foot that
is responsible for the drag, not the shell itself),
there are no significant differences in crawling
speeds between species with presumed low
drag shells (rank categories 2 and 3 pooled)
and high drag shells (rank categories 4
through 6 pooled, P> 0.10, Mann-Whitney U
test). The inference that drag reducing mor-
phologies are an adaptive response to in-
creased surface crawling speed and the sub-
sequent interpretation of life modes in Paleo-
zoic gastropods based on this inference
(Linsley, 1978a,b) do not appear justified in
light of the preceding analysis.

The strong association between shell form
and habitat (Vermeij, 1978 and above) sug-
gests that a safer interpretation of life modes
from shell form may be based on the differ-
ences between surface dwelling and burrow-
ing species. Species exhibiting strong ex-
ternal sculpture will most likely have been
restricted to an open surface existence while
those whose shells are very smooth and
streamlined are likely to have been as-
sociated with some degree of burrowing.

ACKNOWLEDGEMENTS

M. A. R. Koehl, A. J. Kohn and R. T. Paine
critically reviewed the manuscript, providing
useful Suggestions on style and substance. A
brief discussion about shell form with Stan
Rachootin prompted this re-evaluation. Sup-
port while this paper was being written was
provided by NSF grant OCE-77-26901-02 to
R. T. Paine.

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BAYNE, B. L. & SCULLARD, C., 1978, Rates of
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CHAMBERLAIN, J. A., Jr. & WESTERMANN, С. E.
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EDWARDS, D. C. & HUEBNER, J. D., 1977, Feed-
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296 PALMER

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MALACOLOGIA, 1980, 19(2):297-328

SYSTEMATICS OF THE SUBFAMILY CLINOCARDIINAE KAFANOV, 1975
(BIVALVIA, CARDIIDAE)

Alexander |. Kafanov

Laboratory of Chorology, Institute of Marine Biology, Far East Science Center,
Academy of Sciences of the U.S.S.R., Vladivostok, 690022, U.S.S.R.

ABSTRACT

Revising the Cenozoic Cardioidea, the author has established the new subfamily Clino-
cardiinae. The history of studies of clinocardiines, the size and composition of the subfamily and
its systematic position within the Cardiidae are considered. The paper presents keys to tribes,
genera, species and subspecies, and detailed diagnoses for subfamily, tribes, genera and
subgenera. The catalogue raisonné contains all the taxa of species rank (88) described until now
with special notes on the original descriptions, type-localities and the depositories of the type
materials. Necessary taxonomic remarks are given. For Cardium pauperculum Yokoyama,
1923 non Meek, 1871 a new name is suggested: Serripes nodai nom. nov.

Cardiidae are widely represented in Ceno-
Zoic marine deposits of the North Pacific and
European Subarctic. For many stratigraphical
subdivisions the representatives of this group
are either zonal forms or the most character-
istic species. They are also important in the
identification of the Paleogene-Neogene
boundary in the northwestern part of the Pa-
cific mobile belt, and in the North Atlantic they
are one of the most striking participants of the
Neogene trans-Arctic migrations of the North
Pacific molluscs.

Until recently almost all the diversity of
North Pacific cardiids were assigned to only
three genera: Clinocardium s.l., Serripes s.l.
and Papyridea s.|. The revision made by the
author (Kafanov, 1974a, b, 1975, 1976) has
shown that some new taxa of generic rank
and the new subfamily Clinocardiinae should
be established for North Pacific Cardiidae.

The purpose of this paper is to review Re-
cent and fossil Clinocardiinae. The taxonomic
position of this subfamily within the Cenozoic
Cardioidea Lamarck, 1809, is dealt with in
detail in Kafanov & Popov (1977).

On the status of the subfamily
Laevicardiinae Keen, 1936

When discussing the necessity for estab-
lishing a new genus for the North Pacific
“Cerastoderma,” Keen (1936a) proposed the
new subfamily Laevicardiinae. This subfamily
includes forms which may be characterized
by the following diagnosis (Keen, 1969:

N589): “Elliptic-oblique; rib ornamentation of
looped threads or small nodes, not spines:
ribs of posterior slope weaker than those of
central and anterior slopes or obsolescent;
posterior margin wavy rather than notched;
hinge long and arched (line joining laterals
and cardinals bends more than 25 degrees):
cardinal teeth somewhat unequal in size,
anterior left lateral bladelike.”

In this subfamily Keen (1951) originally in-
cluded: Laevicardium Swainson, 1840 (with
the subgenera Laevicardium s.s., Fulvia
Gray, 1853 and Dinocardium Dall, 1900),
Serripes Gould, 1841, Cerastoderma Poli,
1795 (with the subgenera Cerastoderma s.s.,
Parvicardium Monterosato, 1884), Clino-
cardium Keen, 1936, Loxocardium Coss-
mann, 1886 and Plagiocardium Cossmann,
1886 (with the subgenera Plagiocardium s.s.,
Maoricardium Marwick, 1944 and Papilli-
cardium Sacco, 1899). In Keen’s latest (1969)
Classification of the Cardioidea only the
genera and subgenera Laevicardium $.5.,
Laevicardium (Fulvia), Laevicardium (Dino-
cardium), Cerastoderma, Clinocardium and
Serripes are referred to the Laevicardiinae.
More recently Fulvia has been raised to ge-
neric rank (Keen, 1973; Kafanov, 1974a).

Following Keen (1969), the author earlier
adopted an identical interpretation of the
Laevicardiinae (Kafanov, 1974a) but subdi-
vided Clinocardium into Clinocardium s:s.
and two new taxa, Clinocardium (Keeno-
cardium) and Ciliatocardium. A year before,
Clinocardium (Fuscocardium) was proposed
by Oyama (1973). Glibert & van de Poel

(297)

298 KAFANOV

(1970), however, consider the Laevicardiinae
to include Cerastoderma together with the
genus Laevicardium broadly understood by
them and its four subgenera: Laevicardium
s.s., Dinocardium s.s., Clinocardium and
Habecardium Glibert & van de Poel, 1970.
Popov (1977), taking into consideration
Keen's (1950) remarks, considers the latter a
subgenus of Nemocardium Meek, 1876.
More recently it has been found that the
Laevicardiinae sensu Keen are polyphyletic
(Kafanov, 1975; Popov, 1977; Kafanov &
Popov, 1977). According to shell microstruc-
ture (Popov, 1977) and conchological fea-
tures, its genera are subdivided into three dif-
ferent groups: 1) Cerastoderma closely re-
lated to Acanthocardia Gray, 1851 and
Parvicardium on the one hand, and, on the
other hand, to the Ponto-Caspian brackish-
water Lymnocardiinae Stoliczka, 1870; 2)
Laevicardium and Fulvia are similar to
Cardium Linné, 1758, Bucardium Gray, 1853,
Vepricardium lredale, 1929 and Trachycardi-
um Mörch, 1853 and other closely related
genera; 3) Clinocardium 3.1. and Serripes $.1.
differed in their characteristic shell morphol-
ogy and microstructure not observed in repre-
sentatives of other cardiid genera, while
Dinocardium has a microstructure rather simi-
lar to both genera above. Clinocardium 5.1.
and Serripes s.|. were assigned by the author
(Kafanov, 1975) to the new subfamily Clino-
cardiinae. Together with the numerous fea-
tures of morphological similarity, phylogenetic
unity of the genera involved is also confirmed
by the abundant paleontological data.
According to Keen (1936b), Clinocardium
is most closely related to Cerastoderma, from
which it differs by its prosogyrate beaks, its
long, narrow and low ligament, its arched
hinge margin and by its greater number of
radial ribs. Cerastoderma and Clinocardium
s.l., however, have different centres of origin
(Kafanov, 1974a, 1975). Cerastoderma ap-
peared in the Oligocene basins of the Eastern
Paratethys, as is well documented by paleon-
tological data (Merklin, 1974), but the early
stages of the evolution of the Clinocardiinae
occurred in the Northern Japan-Sakhalin
Paleogene province. Therefore, some similar
morphological peculiarities of these two
groups really resulted from convergent devel-
opment and do not indicate common origin.
The Lymnocardiinae in Keen's (1969)
Classification also is not a natural (monophy-
letic) taxon. Comparison of shell morphology
in the numerous genera of the Ponto-Caspian
brackish-water cardiids and the use of data on

shell microstructure (Popov, 1973, 1977) con-
vincingly confirm the view that the overwhelm-
ing majority of taxa of neolimnitic (sensu
Martinson, 1958) genesis arose from
Cerastoderma, namely from some lagoonal
forms like the Recent extremely euryhaline C.
glaucum (Poiret, 1789) (Eberzin, 1965, 1967;
Starobogatov, 1970). The similarity of the
general scheme of the stomach morphology
(Starobogatov in Kafanov & Popov, 1977)
and spermatozoids (Karpevich, 1961, 1964)
in Cerastoderma, Didacna Eichwald, 1838
and Hypanis Menetries, 1832 affirm this origin
unequivocally. However, the brackish-water
cardiids and Cerastoderma are considered
separate by Keen (1969): the former—to be-
long to the independent family Lymnocardi-
idae, the latter to the Laevicardiinae (Cardi-
idae $.5.).

Autochthony of the brackish-water faunas
of the geological past almost unconnected
genetically one with another and their relative
short span of existence as compared with
marine and fresh-water faunas have resulted
in isolation from Cerastoderma of the brack-
ish-water cardiids which occurred independ-
ently at different geological times. Similar
structures, developed in parallel and asyn-
chronously in different branches, recurred in
new evolutionary lines (about eleven). This
process determined the specific features of
“supralimital specialization” (Myers, 1960) of
the Ponto-Caspian groups of neolimnitic
genesis. To the extent that the principle of the
successive monophyly is the basis of con-
struction for each natural system, Cerasto-
derma and the overwhelming majority of
Ponto-Caspian brackish-water genera must
be incorporated into one taxon of high rank
(Kafanov, 1975; Popov, 1977; Kafanov &
Popov, 1977). Only such a taxonomic inter-
pretation shows the phylogenetic unity of all
brackish-water cardiids. Hence, there is no
place for Cerastoderma within the Laevicardi-
inae.

The taxonomic position of Dinocardium is
the most mysterious. Shell configuration,
costal ornamentation (transverse toruli or
tubercula on the ridges) and the presence of
the rudimentary external layer of the simple
prismatic structure (Popov, 1977) resemble
analogous characters in Clinocardium. How-
ever, it differs from the latter as follows (Fig.
1): 1) proximal end of the anterior part of
hinge margin covers the anterior beak slope,
frequently observed in Laevicardium and
Trachycardium; 2) lunula formed by “lapel” of
proximal end of the anterior part of hinge

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 299

margin, and from anterior preapical valve sur-
face restricted by deep vallicula; 3) scars of
the dorso-umbonal muscles were not found,
and 4) ligament is considerably higher and
shorter than in Clinocardium and Serripes.
According to the author (Kafanov & Popov,
1977), it would be better to consider Dino-
cardium a member of the Cardiinae until addi-
tional data are obtained.

Only Laevicardium and Fulvia, therefore,
remain in the Laevicardiinae. Cerastoderma,
Clinocardium s.l., Serripes si. and Dino-
cardium are considered to be separate.

Clinocardiinae Kafanov, 1975

The subfamily Clinocardiinae represents a
discrete natural group. Clinocardium s.|. and
Serripes s.l. assigned to this subfamily are
distinguished by a rare type of shell micro-
structure and in this character they are very
different from the other genera of Cardiidae
(Oberling, 1964; Popov, 1973, 1977).

Stewart (1930) and Keen (1936a) were the
first to establish a new genus for a fairly nu-
merous group of the North Pacific Recent and
fossil species, previously referred by most
authors to either Cerastoderma or Laevi-
cardium. Stewart (1930) discusses in some

detail the relationship of Cardium nuttallii
Conrad, 1837 (= Cardium corbis auct. plur.)
to Dinocardium, and he includes Cerasto-
derma s.s. and Cerastoderma (Dinocardium)
in the subfamily Trachycardiinae established
by him, taking note, however, of their consid-
erable similarity with the Cardiinae. Keen
(1936b) proposed a new genus Clinocardium
(type-species Cardium nuttallii Conrad, 1837)
and referred it to the Laevicardiinae which in-
itially incorporated eleven species.

The name Clinocardium has been used in
most hydrobiological and _ paleontological
papers and has been commonly accepted.
However, Clinocardium sensu Keen is a high-
ly nonhomogeneous group from the morpho-
logical point of view. As long ago as 1934,
Makiyama, in classifying the North Pacific
Tertiary “Cerastoderma,” suggested the dis-
tinction of three groups of species including
Cardium decoratum Grewingk, 1850 (nomen
dubium, most probably included in Clino-
саит s.s.), Cardium californiense
Deshayes, 1839 and Cardium ciliatum
Fabricius, 1780, according to the sculptural
peculiarities of the external shell surface.
Thus, the problem of the homogeneity of
Clinocardium was discussed before a formal
determination of the genus. Chinzei (1959)
especially distinguished a group with ribs tri-

FIG. 1. Hinge structure in Dinocardium robustum (Lightfoot, 1768) (a-b) (Dinocardiini) and Clinocardium

nuttallii (Conrad, 1837) (c-d) (Clinocardiini).

300 KAFANOV

angular in cross section from Neogene
Japanese Clinocardium, but Shuto (1960)
emphasized that the majority of the Clino-
cardium representatives differed from type-
species in the character of the radial ribs. The
same author foresaw the possibility of sepa-
rating some subgenera from the genus.
Analysis of the Recent and fossil forms as-
signed by Keen (1936b, 1954, 1973) to
Clinocardium has shown that according to
their morphological peculiarities and above all
to the type of structure in transverse section of
the radial ribs (Fig. 2) they form three taxa,
separated by discontinuities, well differenti-
ated from each other and representing the
single phylogenetic lines which agree with the

criteria for generic groups of Mayr (1971).
These groups include the Recent Cardium
nuttallii, С. californiense and С. ciliatum,
respectively, which were designated the type-
species for Clinocardium s.s., Clinocardium
(Keenocardium) Kafanov, 1974 and Ciliato-
cardium Kafanov, 1974. In the present paper
Keenocardium is raised to generic rank. The
considerable morphological differences be-
tween Clinocardium s.s. and Keenocardium,
various trends in their historical development
and major changes of the adaptive zones of
these two groups (Kafanov, unpublished)
suggest the change in rank, as does the ne-
cessity of the taxonomic separation of Clino-
cardium (Fuscocardium) which is much

«.
ae 4

des

ша:

FIG. 2. Rib structure in Clinocardium (а), Keenocardium (b) and Ciliatocardium (с)

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 301

closer to Clinocardium s.s. than to Keeno-
cardium. lt should be emphasized that both
conchological and anatomical differences
(see key to the genera and diagnoses of the
corresponding taxa) are the basis for subdivi-
sion of Clinocardium sensu Keen into three
genera.

Similarly, the genus Serripes proves to be
nonhomogeneous. At present among all the
known species and subspecies five forms
grouped around the Recent Cardium
(Serripes) notabile Sowerby, 1915 perfectly
form the isolated morphological and evolu-
tionary lineages. The representatives of this
group are distinguished by the carinate and
markedly convex shells with narrow anterior
margins, by strongly prosogyrate beaks, by
more completely developed hinges, by the
position and details of structure of anterior

lower lateral teeth and also by topography of
the rudimentary radial sculpture different from
that of the typical Serripes (Fig. 3). For this
group the author (Kafanov, 1975) erected a
new genus Yagudinella.

Despite the definite morphological similarity
of Serripes, Yagudinella, Clinocardium s.s.,
Clinocardium (Fuscocardium), Keeno-
cardium and Ciliatocardium, the first two
genera are more closely related to each other
than to the other four, from which they differ in
their strong reduction of the sculpture on the
external valve surfaces and the less devel-
oped hinge. These differences enabled us to
subdivide the Clinocardiinae into two tribes as
follows: Clinocardiini and Serripedini

(Kafanov, 1975), in perfect agreement with
some internal shell structure as well (Popov,
1977).

FIG. 3. Hinge structure in Serripes groenlandicus (Bruguière, 1789) (a) and Yagudinella notabilis (Sowerby,

1915) (b).

302 KAFANOV

IAS
ESOS

Zl
Sif

FIG. 4. Rib arrangement in Clinocardiini (a) and Profulviini (b).

The Far Eastern Tertiary “Рарупаеа” be-
ing extremely unusual and referred by the
author (Kafanov, 1976) to the new genus
Profulvia (type-species: Papyridea harrimani
Dall, 1904), form the third tribus. The repre-
sentatives of this tribus differ from the other
Clinocardiinae by their carinate shells, ante-
rior and posterior gapes, with nearly ortho-
gyrate or slightly opisthogyrate apex and by
the nature of the costae on the posterior valve
surface: arched ribs with convexity anteriad
while in the other Clinocardiinae the convexity
is posteriad (Fig. 4).

The classification of the Clinocardiinae
adopted in the present paper is the following
one:

Family Cardiidae Lamarck, 1809
Subfamily Clinocardiinae Kafanov, 1975

Tribus Clinocardiini Kafanov, 1975
Genus Clinocardium Keen, 1936
Subgenus Clinocardium Keen, 1936
Subgenus Fuscocardium Oyama, 1973
Genus Keenocardium Kafanov, 1974 grad.
nov.
Genus Ciliatocardium Kafanov, 1974
Tribus Profulviini Kafanov in Kafanov & Po-
pov, 19771
Genus Profulvia Kafanov, 1976
Tribus Serripedini Kafanov, 1975
Genus Serripes Gould, 1841 (ex Beck, MS)
Genus Yagudinella Kafanov, 1975

Key to the tribes, genera and subgenera of Clinocardiinae:

(Serripedini Kafanov, 1975)

2. Carina nearly obsolete; shell without gapes; ribs on the posterior valve surfaces convex back

(IGE: Aa) a sur Che eee

(Clinocardiini Kafanov, 1975)

Shell carinate, gaping at the back or from both sides; ribs on posterior valve surfaces curved

with convexity forward (Fig. 4b) ..........

een ER Profulviini Kafanov in Kafanov et Popov, 1977 (the monotypic tribus)

. Ribs rounded, flattened or nearly rectangular in cross section, not placed on anterior valve
surfaces; ridges of ribs with frequent transverse nodular tubercula or nearly smooth .... 4
Ribs triangular or roof-like in cross section (Fig. 2c) and often widely extended on the anterior
valve surfaces; ridges of ribs with longitudinal rows of thin ciliated periostracum fringes (in
poorly preserved fossil shells ribs may be differently smoothed) ........................

RE Ge Ee ER A E crc Ciliatocardium Kafanov, 1974

. Beaks high; ribs about 20-40 in number; ridges of ribs with transverse nodular tubercula (Fig.

2a); labial palps short, about one-fourth length of the inner demibranch ............... 5
(Clinocardium Keen, 1936)

lProfulviini Kafanov et Popov’ as published with the original description is a typographical error.

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 303

Beaks low; ribs about 28-65 in number; nodular tubercula absent on ridges of ribs (Fig. 2b);
labial palps relatively long but less than half the length of the inner demibranch .........

TY DR EU EIN SS Bucher thd er ES о eee Keenocardium Kafanov, 1974
. Intercostal interspaces appreciably narrower than ribs: ribs about 30-40 in number, flattened

andtoundediniCoss Section Mn... RN... PR OA Clinocardium $.5.
Width of intercostal interspaces nearly equal to width of ribs; ribs about 20-30 in number,
rectangularin' cross Section... Clinocardium (Fuscocardium) Oyama, 1973

. Beaks moderately prosogyrate or nearly orthogyrate; rudiments of radial ribs mainly observed
on the posterior valve surfaces; hinge strongly reduced, frequently teeth completely absent:
bases of the anterior lower lateral teeth lie on outer side of the internal branches of hinge
паг юар ет MEME оо ОВО о A ey Serripes Gould, 1841 (ex Beck, MS)
Bases obviously prosogyrate; rudiments of radial ribs largely presented on the anterior valve
surfaces; hinge normal for Clinocardiinae; bases of the anterior lower lateral teeth tend to be
on ventral side of the anterior branches of hinge margin, but their proximal parts elongated

milhinäthe/Beaksilkige 3b... ER ER NN Yagudinella Kafanov, 1975.

Composition of the Clinocardiinae
Kafanov, 1975

At present about 73 valid taxa of specific
and subspecific rank are referred to the Clino-
cardiinae; 5 taxa are provisionally referred to
this subfamily. A complete list of them was
lacking. Slodkewitsch (1938) gives the de-
tailed review of the North Pacific Tertiary
“Papyridea.” Keen (1954) lists about 18
nominal species of Clinocardium $.1. and de-
scribes three new species from Neogene for-
mations of northwestern America. Noda
(1962) gives a systematic review of the
Japanese Serripes s.l. Keen (1973) lists Far
Eastern Clinocardium s.l., Serripes s.l. and
Fulvia (including Profulvia). A list of Clino-
cardiini has previously been given by the
author (Kafanov, 1974a). The known repre-
sentatives of Yagudinella are also listed by
Kafanov (1975). Finally, there is a very in-
complete list of Clinocardium si. and
Serripes s.|. in Popov's (1977) monograph.

The author excludes from the Clinocardii-
nae the following forms assigned by Keen
(1973) to Clinocardium and Serripes:
Cardium annae Pilsbry, 1904: 557, pl. 40, fig.
20; Vasticardium arenicoloides Akutsu, 1964:
284, pl. 59, figs. 6, 7; Laevicardium (Cerasto-
derma) etheringtoni Slodkewitsch, 1938 (ex
Kogan, MS): 388, pl. 74, figs. 11, 11a, 12;
Cardium (Trachycardium) hanpeizanense
Nomura, 1933: 77, pl. 1, figs. 7, 8, pl. 2, figs. 8,
9; Cardium (Cerastoderma) hanzawai
Nomura, 1933: 79, pl. 3, figs. 18, 19; Cardium
(Cerastoderma) hizenense Nagao, 1928:
61(51), pl. 10, figs. 15-17; Cardium coosense
rhomboideum Khomenko, 1934: 52, pl. 12,
figs. 5, 6; Vasticardium shimotokuraense
Akutsu, 1964: 283, pl. 59, figs. 9, 10. Laevi-
cardium (Cerastoderma) esutoruense Krishto-
fovich, [1957]: 93, pl. 16, figs. 4, 5, 6, 6a, 8,13,

mentioned by the author as Keenocardium
(Kafanov, 1974: 1469) is Laevicardium.

Cardium (Laevicardium) jobanicum
Yokoyama, 1924: 15, pl. 2, figs. 12-18 from
the Oligocene Iwaki formation of the north-
eastern part of the Central Honshu included
by Keen (1973) in Clinocardium, must be
considered a member of the Veneridae, either
Protothaca (Hatai & Nisiyama, 1952) or
Cyclina Deshayes, 1849 non Gray, 1857
(Kamada, 1962).

Popov (1977) refers Cardium gallicum
Mayer, 1866: 72, pl. 2, fig. 3 and Cardium
(Laevicardium) pantecolpatum Cossmann &
Peyrot, 1911: 517, pl. 23, figs. 32-35 from the
Miocene of France, as well as Cardium
(Cerastoderma) scapoosense Clark, 1925:
91, pl. 22, fig. 5 and Cardium sookense Clark
8 Arnold, 1923: 145, pl. 22, figs. 1a-b, 2 from
the Oligocene of the Pacific coast of the North
America to Clinocardium. The first two spe-
cies have nothing in common with Clinocardi-
um or with the Clinocardiinae in general.
Generic relationship of the latter two forms is
uncertain. The considerably shortened and
strongly curved hinge margin, nearly ortho-
gyrate beaks, cardinal teeth (with hyper-
trophied anterior tooth of the left valve in C.
sookense) which are strong, straight and mis-
placed with respect to each other—all prevent
us from assigning these two species to the
Clinocardiini. It is noteworthy that Keen
(1936b, 1954) does not mention either C.
scapoosense and C. sookense as belonging
to Clinocardium. One therefore should ex-
amine all the related groups to see whether
one might be found with characters that would
overlap.

Cardium (Trachycardium) kinsimarae
Makiyama, 1934: 141, pl. 6, fig. 35 and Cardi-
um puchlense llyina in Zhizhchenko, Korob-
kov, Krishtofovich & Eberzin, 1949: 144, pl.

304 KAFANOV

28, figs. 6-8, mentioned as Clinocardium in
Zhidkova et al. (1974) are also excluded from
the subfamily. Cardium taracaicum Yoko-
yama, 1930: 414, pl. 77, figs. 1, 2, called
Clinocardium in some papers (Makiyama,
1959; Zhidkova et al., 1974; Sinelnikova et al.,
1976), the author, following Keen (1973), be-
longs in Laevicardium $.1.

Cardium hudsoniense Deshayes, 1855:
331, a possible holotype of which is figured by
Fischer-Piette (1977: pl. 12, fig. 1), should be
considered a Parvicardium, not as a Corcu-
lum (Keenocardium).

Diagnoses of the subfamily, tribes and taxa
of the generic group, as well as annotated
catalogue and keys of all known species and
subspecies with indications of type-localities
and depositories, are given below. Valid taxa
of the specific group are emphasized with
boldface in the text. Nomina nuda are not ex-
amined.

Subfamily Clinocardiinae Kafanov, 1975

Kafanov,1975: 146.

Shell medium-sized or fairly large (to
120 mm and more), from truncate-trigonal to
oblong-elliptical or neary ovate. Valve height
usually less than length (H = 0,926 -
0,995 +0.013 for the whole subfamily). Beaks
prosogyrate, nearly orthogyrate or slightly

opisthogyrate. Radial ribs about 20-65 in
number. Ribs flattened and rounded, tectate
or triangular in cross-section; combinations of
these types are possible. Ribs smooth or with
transverse nodular tubercula (but never with
scales) or decorated with longitudinal rows of
thin ciliated periostracal fringes (Fig. 2a-c).
When sculpture of the external shell surface is
obsolete, traces of the radial ribs will be found
`п posterior or rarely anterior valve surfaces.
Hinge often strongly reduced. Typically there
are (Fig. 1c-d): paired anterior lateral, paired
cardinal and single posterior lateral teeth in
right valve; paired cardinal and single lateral
teeth in left valve. Reduction of the hinge ele-
ments is more often provided by that of the
anterior upper lateral tooth of the right valve
and of cardinal teeth. Posterior lateral tooth of
the left valve may be split into two branches in
distal part. Lunula and area are weak or ab-
sent. Ligament is long, narrow and low. Shell
three-layered; mesostracum with cross-
lamellar structure, ectostracum isolated and
formed by spinose prisms or thin vertical
plates oriented perpendicular to valve sur-
faces.

Paleocene(?)-Eocene-Recent; cold and
temperate waters of the Northern Hemi-
sphere, Paleogene and Neogene deposits of
the North Pacific, North Atlantic and Arctic
(Figs. 5-10).

FIG. 5. Geographical and geological distribution of Clinocardium. 1—Recent; 2—Miocene; 3—Pliocene;
4— Pleistocene.

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 305

Tribus Clinocardiini Kafanov, 1975

Kafanov, 1975: 147.

Carina obsolete. Shell without gapes. Ribs
well developed. Ribs on posterior part of valve
posteriorly convex (Fig. 4a).

Geographical and geological distribution as
in the subfamily.

Genus Clinocardium Keen, 1936

Clinocardium Keen, 1936b: 119;
Clinocardium (Clinocardium)
Kafanov, 1974a: 1468.
Type-species: Cardium nuttalli Conrad,
1837; Recent, off estuary of the Columbia
River, Oregon, U.S.A. (original designation).
Shell medium-sized or large (to 100 mm
and more), from flattened to fairly convex,
oblong-elliptical or truncate-trigonal, inequi-
lateral. Beaks high and prosogyrate. Ribs
about 20—40 in number; ridges with trans-
verse nodular tubercula sometimes slightly

Keen:

smoothed (Fig. 2b). Ribs flattened and
rounded or rectangular in cross-section. An-
terior lower lateral tooth of right valve with a
small longitudinal ridge on dorsal surface.
Lunula often well developed, lanceolate. Dis-
tal part of foot with narrow ventral sulculus
surrounded on both sides by longitudinal rows
of low papillae. Labial palps short, about one-
fourth length of the internal demibranch.
Two subgenera—Clinocardium s.s. and
Clinocardium (Fuscocardium) Oyama, 1973.
Middle Miocene-Recent; North Pacific
(north to 60°N, south to Central Honshu and
southern California, U.S.A.) (Fig. 5).

Subgenus Clinocardium Keen, 1936

Intercostal interspaces appreciably nar-
rower than ribs. Ribs about 30—40 in number.
Ribs flattened and rounded in cross-section;
ridges with transverse nodular or tabular-
shaped tubercula.

Geographical and geological distribution as
in genus.

Key to the species and subspecies2

1. Average rib number about 34-35.........
Average rib number about 28-30 ........

2. Anterior margin of shell moderately narrower than their posterior margin ................

A Tee meekianum meekianum (Gabb, 1866).

Anterior margin of shell much more narrower than their posterior margin ................

Described taxa

californianum Conrad, 1837: 229, pl. 17,
fig. 4 [Cardium]. Recent; vicinity of Santa
Barbara, Califonia. Depository: unknown.
Synonym of Clinocardium (C.) nuttallii (Con-
rad, 1837).

corbis auct. plur., non Corbis Martyn, 1784,
Taf. 80; non-binom. (Official Index... , 1958:
11, Opinion 456). Synonym of Clinocardium
(C.) nuttallii (Conrad, 1837).

? decoratum Grewingk, 1850: 347, pl. 4,
figs. 3a-g [Cardium]. Unga Island, Alaska
(type-locality here designated); "jüngsten
Tertiárzeit” [Middle or Upper Miocene]. De-
pository: unknown. Due to the loss of the type
material and inferiority of the original descrip-
tion and illustration decoratum must be con-
sidered a nomen dubium. Possible synonym
of Clinocardium (C.) nuttallii (Conrad, 1837).
Its taxonomic position will be considered in
detail elsewhere (Kafanov, in press).

2Taxa conditionally included in the genus are not considered.

à ELITE meekianum myrae Adegoke, 1969

meekianum Gabb, 1866: 27, pl. 7, fig. 46
[Cardium]. Eagle Prairie, Humboldt County,
California: Pliocene [Wildcat formation ac-
cording to Keen & Bentson, 1944]. Depository
(holotype): Academy of Natural Sciences of
Philadelphia, Philadelphia, U.S.A., reg.no.
4497.

meekianum myrae Adegoke, 1969: 117,
pl. 3, figs. 7, 9, pl. 7, fig. 6 (paratypes)
[Clinocardium]. Kettleman Hills area, San
Joaquin Valley, California; Etchegoin Forma-
tion, Lower Pliocene. For figure of holotype
see Woodring et al., 1941: pl. 29, fig. 14. De-
pository (holotype): U.S. National Museum,
Washington, U.S.A., reg. no. 495769.

? nanum Khomenko, 1931: 74, pl. 10, fig.
19 [Cardium]. Ekhabi, Okhinskij District,
Eastern Sakhalin; Ekhabinskaya suite, Middle
Miocene. Depository (holotype): Central Re-
search geological prospecting Museum,
Leningrad, USSR, reg. no. 28/3456. A juven-
ile specimen.

306

nuttallii Conrad, 1837: 229, pl. 17, fig. 3
[Cardium]. Recent; “muddy salt marshes, a
few miles from the estuary of the Columbia
River,’ Oregon. Depository (lectotype):
Academy of Natural Sciences of Philadelphia,
Philadelphia, U.S.A., reg. no. 54036. Recent
records: along the Pacific coast of North
America from San Diego, California, to
Nunivak Island; Aleutian, Pribiloff and Com-
mander Islands; Eastern Kamchatka (north to
Sivuchij Cape); northern Kurile Islands
(Paramushir); Hokkaido (along the Pacific
side to Hakodate). Fossil records: Ilyinskaya
suite of Western Kamchatka (Middle Mio-
cene), San Pablo Formation of California
(Upper Miocene), Enemtenskaya suite of
Western Kamchatka (Lower Pliocene), Plio-
cene Montesano, Empire and Quillayute for-
mations of Oregon and Washington, Pliocene

Key to

Average number of ribs about 20-22
Average number of ribs about 27-30

Described taxa

braunsi Tokunaga, 1906: 51, pl. 3, fig. 11
[Cardium]. Oji, near Tokyo; “Upper Musa-
shino,” Pleistocene. Possible depository: Col-
lege of Sciences, University of Tokyo, Tokyo,
Japan. Characteristic species in Pleistocene
deposits of the Kanto region, Central Honshu
(Katori, Sakishima, Atsumi, Uemachi, Takino-
kawa and Toshima formations) and Eastern
Sakhalin (“Nadnutovskaya” suite). Unknown
in the Recent.

? nomurai Hayasaka, 1956: 18, pl. 2, figs.
4a-b [“Clinocardium.”] Path side cutting at
Onoda, Futaba District, Fukushima Prefec-
ture, Honshu; Ishiguma formation, Pliocene,
Depository (holotype): Institute of Geology
and Paleontology, Tohoku University, Sendai,
Japan, reg. no. 77376. Assignment of a given
species to this subgenus is very difficult be-
cause of poor preservation. Hayasaka (I.c.)
compares it to Clinocardium nuttallii (Conrad,
1837). According to the author, however, the
form described here is more closely related
to Clinocardium (Fuscocardium) braunsi
(Tokunaga, 1906).

ovata Yokoyama, 1922: 157, pl. 12, fig. 4

KAFANOV

Purisima, Etchegoin and Falor formations of
California, Pleistocene of Alaska, Aleutian
Islands, Kamchatka, Sakhalin, Washington,
Oregon and California.

Subgenus Fuscocardium Oyama, 1973

Clinocardium
1973: 100.

Type-species: Cardium braunsi Tokunaga,
1906; Pleistocene, environs of Tokyo, Japan
(original designation).

Width of intercostal interspaces nearly
equal to width of ribs. Ribs about 20-30 in
number, rectangular in cross-section. Trans-
verse tabular-shaped tubercula on crests or
ribs smooth.

Middle Miocene-Pleistocene;
Sakhalin and Kamchatka.

(Fuscocardium) Oyama,

Honshu,

species

braunsi (Tokunaga, 1906)
pseudofastosum (Nomura, 1937)

[Cardium tokunagal var.]. Shisui, Chiba Pre-
fecture, Honshu; “Upper Musashino,” Pleis-
tocene. Depository: Geological Institute, Uni-
versity of Tokyo, Tokyo, Japan, reg. no. ?.
Synonym of Clinocardium (Fuscocardium)
braunsi (Tokunaga, 1906).
pseudofastosum Nomura, 1937: 171, pl.
23, figs. 1 (holotype), 2 [Cardium (Clinocardi-
um)]. Kitamata-gawa, along the upper course
of Koromogawa, Isawa District, lwate Pre-
fecture, Honshu;3 Yushima formation (Hatai &
Nisiyama, 1952), Pliocene. Depository (holo-
type): Saito Ho-on Kai Museum, Sendai,
Japan, reg. no. 2388. Very similar forms were
reported from Ilyinskaya suite of western
Kamchatka (Kafanov & Savitzky, in press).
tokunagai Yokoyama, 1922: 156, pl. 12,
figs. 6 (lectotype; designated as holotype by
Taki & Oyama, 1954: pl. 32), 5 [Cardium].
Otake, Chiba Prefecture, Honshu; “Upper
Musashino,” Pleistocene. Depository (lecto-
type): Geological Institute, University of
Tokyo, Tokyo, Japan, reg. no. ?. Synonym of
Clinocardium (Fuscocardium) braunsi
(Tokunaga, 1906). Following Taki & Oyama
(Taki & Omaya, 1954; Oyama, 1973) who
saw Yokoyama's materials, the author con-

3For detailed type-localities of Japanese species (Paleogene and Neogene) described prior to 1952 see Hatai & Nisiyama,

1952

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 307

FIG. 6. Geographical and geological distribution of Keenocardium. 1—Recent; 2—Oligocene; 3—Miocene;
4—Pliocene; 5—Pleistocene.

siders C. tokunagai and C. tokunagai var.
ovata to be Clinocardium (Fuscocardium)
braunsi (Tokunaga, 1906).

Genus Keenocardium Kafanov, 1974

Clinocardium (Keenocardium) Kafanov,
1974a: 1468.

Type-species: Cardium californiense
Deshayes, 1839; Recent, [Eastern] Kam-

chatka (original designation).

Shell medium-sized (to 80 mm and more),
elongated and rounded or oval-trigonal, in-
equilateral, slightly convex. Beaks only weak-
ly prosogyrate, displaced somewhat forward,
narrow, slightly elevated. Ribs about 28-65 in

number, rounded or flattened and rounded in
cross-section, separated by narrower inter-
costal spaces; ribs, as a rule, closely set on
anterior part of valve. Costal surfaces smooth,
interrupted by narrow concentric wrinkles
only. Anterior lower lateral tooth of right valve
frequently with a small longitudinal ridge on
dorsal surface. No lunula and escutcheon.
Distal part of foot with narrower ventral
sulculus Surrounded оп both sides by
smoothed magins. Labial palps long but less
than a half the length of the ‘riner demibranch.

Early Oligocene—Recent; North Pacific
(southern to Korea, Northwestern Kyushu and
southern California), Bering Strait and North-
western Alaska (Fig. 6).

Key to the species and subspecies

1. Ribs of posterior area crowded and crumpled into an irregular channel .............. Pe
Ribs of posterior area not forming an irregular channel ............................ 3

2. Average rib number about 44-46 .......
Average rib number about 49-51.......

californiense californiense (Deshayes, 1839).
californiense uchidai (Habe, 1955).

3. Shell ovate, rounded, orbicular, suborbicular or semi-quadrate in outline; posterior dorsal

margin not sloping obliquely downward ........................................... 4.
Shell trigonal in outline; posterior dorsal margin sloping obliquely downward ........ IS:
4. Maximum size of adult shell more than 40 mm .................................... 5:

Maximumsize of-adultrshellifewer than 40 MM Seen ee EEE CE EN EEE 7.

308 KAFANOV
5. Shell strongly inequilateral (beaks near the anterior 0,35—0,37); ribs 30-33 ............
RE der ltd AIR os бое ВО iwasiroense (Nomura, 1935).
Shell subequilateral (beaks near the anterior 0,42-0,45); ribs 44-60 ................. 6.
6. Height of shell less than length (average height/length ratio about 0,94-0,95); ribs 50-60
separated by much narrower interspaces................ fastosum (Yokoyama, 1927).
Height of shell nearly equal to length (average height/length ratio about 1,00); ribs 44-49
sepated by somewhat narrower interspaces .................... coosense (Dall, 1909).
7 Ribse4: Or Moret: . MER... Le SN 8.
Ribssfewerthantas 8 ce See hs... SG A N 1 EEE 10.
8. Shell semi-quadrate in outline; interspaces about equal to the width of the ribs.........
Dos Ps SRLS SERRES. С АСЯ ARE okushirense (Uozumi & Fujie, 1966).
Shell ovate or suborbicular in outline; interspaces somewhat narrower than the width of the
VIDS: SLR ee RS О DESIRE. 0, 2 ee 9.
9. Shell subequilateral (beaks near the anterior 0,43); average height/length ratio about 0,86—
TA Ace RE ia el elena ee een rl eames A Burgen ballet, Se fucanum (Dall, 1907).
Shell inequilateral (beaks near the anterior 0,38); average height/length ratio about 0,95—
DOG RL Ay SR a ed th: Mat MR ri el ag e subdecussatum (Shuto, 1960).
1104 ЕЮ. SS OF feWer qee enano Hien soe aos ue de Sas AE A O At.
PISS HSA ce ем mu a Shin ie ue sa ayia В и Ne en TIRE 12:
11. Average height/length ratio about 0,96; interspaces narrower than the width of the ribs .
A A A о Ro SE andoi (Itoigawa & Shibata, 1975).
Average height/length ratio about 0,86; interspaces about equal to the width of the ribs or
EVENLSOMeWh ali DIOAGE za ur anne kljutschiense (Krishtofovich, 1969).
12. Shell equilateral (beaks near the anterior 0,49) ................ blandum (Gould, 1850)
Shell subequilateral (beaks near the anterior 0,44) ......... arakawae (Kamada, 1962)
13. Maximum size of adult shell more than 45 mMmM.........:.......0 ES 14.
Maximum size of adult shell less than 45 mm... 0000 =... 22.02 00 pe 16.
14. Ribs fewer than 40; interspaces about equal to the width of the ribs . buelowi (Rolle, 1896).
Ribs more than 40; interspaces much narrower than the width of the ribs .......... 15:
1511424800 om ooo Re ee he ipsum aes pristinum (Keen, 1954)
РБ 655 ar da E MERE ДИ lisoum (Roth & Talmadge, 1975).
6 RIOS аромате енко tay. Harpe ARE hopkinsi (Kanno, 1971).
RibSL 35-40: pipet dat лора Коми. Ls BIL ee: IO TERRES ure
17 wAverage height/length:ratio about: 100) .. . . m. pen hannibali (Keen, 1954)
Average height/length ratio about 0,96.................... praeblandum (Keen, 1954)
Described taxa tory (lectotype): U.S. National Museum,

andoi ltoigawa & Shibata, 1975: 24, pl. 7,
figs. 9a-b (holotype), pl. 8, figs.1-4 [Clino-
cardium]. Togari-ST, Akeyo-cho, Mizunami
City, Gifu Prefecture, Honshu; Mizunami
Group, Yamanouchi member, Miocene. De-
pository (holotype): Mizunami Fossil Mu-
seum, Mizunami City, Japan, reg. no. 10029.

arakawae Kamada, 1962: 105, pl. 10,
figs. 15 (holotype), 16, 17 [Clinocardium
asagaiense arakawae]. Mukaida, Yumoto-
machi, Joban City, Joban coal-field, Honshu;
Asagai Formation, Oligocene. Depository
(holotype): Institute of Geology and Paleon-
tology, Tohoku University, Sendai, Japan,
reg. no. 79383. For taxonomic notes see:
Kafanov, 1974a: 1470.

blandum Gould, 1850: 276; 1852: 418;
1861: 14, pl. 36, figs. 534, 534a [Сагашт].
Recent; Puget-Sound, Washington. Deposi-

Washington, D.C., U.S.A., reg. no. 3899. For
figure of lectotype see: Schenck & Keen,
1940: pl. 2, figs. 17-20; Schenck, 1945: pl. 67,
figs. 18-21.

boreale Broderip & Sowerby, 1829: 368
non Reeve, 1845, sp. 131, pl. 22 [Cardium].
Recent (?); Ice-Cape, Arctic coast of Alaska.
Depository: unknown. Nomen oblitum pre-
sented to International Commission on Zoo-
logical Nomenclature for inclusion in Official
Index of rejected and invalid names in zoo-
logical nomenclature (Kafanov, 1974b; see
also: Mayr & Melville, 1976). Synonym of

Keenocardium californiense (Deshayes,
1839).
brooksi MacNeil in MacNeil, Mertie &

Pilsbry, 1943: 91, pl. 15, fig. 14 [Cardium
(Cerastoderma) ciliatum brooksi] non Clark,
1943: 812, pl. 18, fig. 5 [Cardium (Papyri-
dea)]. Intermediate Beach, between Center

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 309

and Bourbon Creeks, near Nome, Alaska;
Anvillian Pleistocene. Depository (holotype):
U.S. National Museum, Washington, D.C.,
U.S.A., reg. no. 499085. Synonym of Keeno-
cardium californiense (Deshayes, 1839).
buelowi Rolle, 1896: 114, pl. fig. C [Cardi-
um]. Recent; Yokohama, Honshu. Depository
(possible syntypes): Museum fur Naturkunde,
Humboldt-Universität, Berlin, G.D.R.
californiense Deshayes, 1839: 360;
1841a, pl. 47 (nom. conserv. propos., see:
Kafanov, 1974b) [Cardium]. Recent; [Eastern]
Kamchatka (here limited: in 1836 the region of
investigations conducted by the French expe-
dition on “Venus” near Kamchatka visited
only the eastern coast and the lectotype is
derived from those materials; Deshayes in the
Original description mentions this species
form “Cótes de Californie” where it is absent).
Depository (lectotype): Muséum National
d'Histoire Naturelle, Paris, France, reg. no. ?.
Recent records: Korea, northern and central
Honshu (along the Pacific coast to Boso
Peninsula, along the Sea of Japan coast to
Noto Peninsula, Hokkaido, South Primorje,
Sakhalin, Kurile Islands, Sea of Okhotsk,
Kamchatka, Commander and Aleutian
Islands, Southern Chukotka; along the Pacific
coast of North America southward to Sitka
Island, Alaska, and Vancouver Island (7),
British Columbia. Fossil records: Kakertskaya
and Etolonskaya suites of Kamchatka (Middle
Miocene), lower and middle parts of
Maruyamakaya suite of Sakhalin (Middle and
Upper Miocene), Miocene Utsutoge, Hitosao
and Gobansoyama formations of Honshu,
lower part of Limimtevayamskaya suite of
Karaginskij Island (Upper Miocene or Lower
Pliocene), Empire Formation of Oregon
(Lower Pliocene), upper part of Limimte-
vayamskaya and Ustj-Limimtevayamaskaya
suites of Karaginskij Island (Pliocene),
Nutovskaya, Uranajskaya, Ekhabinskaya,
Pomyrskaya and upper part of Maruyam-
skaya suites of Sakhalin (Pliocene), Pliocene
Setana formation of Hokkaido and Kotari for-
mation of Honshu, Beringian strata and their
equivalents of Alaska (Upper Pliocene), Pleis-
tocene of Pribiloff Islands, Chukotka, Koryak
Plateau, Kamchatka, Kurile Islands, Sakkalin
and North Japan.
coosense Dall, 1909: 118, pl. 13, figs. 3, 4
[Cardium (Cerastoderma)]. Coos Bay, Ore-
gon; Empire formation, Lower Pliocene. De-
pository (holotype): U.S. National Museum,
Washington, D.C., U.S.A., reg. no. 153933.
fastosum Yokoyama, 1927a: 178, pl. 48,

fig. 5 [Cardium]. Kanazawa, Nagaya, Kosaka-
mura, Kahoku District, Ishikawa Prefecture,
Honshu; Onma formation, Lower Pliocene.
Depository (holotype): Geological Institute,
University of Tokyo, Tokyo, Japan, reg. no. ?.
Makiyama (1959) referring to the personal
communication of T. Kuroda, considers this
species a synonym of Keenocardium cali-
forniense (Deshayes, 1839). This assignment
iS incorrect.

fucanum Dall, 1907: 112 [Cardium]. Re-
cent; Juan-de-Fuca Strait, Puget-Sound,
Washington. Depository (holotype): U.S. Na-
tional Museum, Washington, D.C., U.S.A.,
reg. no. 427773. For figure of holotype see:
Schenck & Keen, 1940: pl. 2, figs. 21-24;
Schenck. 1945: pl. 67, figs. 22-25.

hannibali Keen, 1954: 18, pl. 1, fig. 16
(holotype), text-fig. 9 [C/inocardium].
Chehalis and Summit Sts., Aberdeen, Wash-
ington; Montesano formation, Lower Plio-
cene. Depository (holotype): Stanford Univer-
sity, Paleo. Type collection, Stanford, U.S.A.,
reg. no. 8302.

hopkinsi Kanno, 1971: 68, pl. 5, figs. 7
(holotype), 6a-b [Clinocardium]. Near the
head of the Gulf of Alaska; upper part of the
Poul Creek formation, Lower Miocene(?). De-
pository (holotype): Tokyo University of Edu-
cation, Tokyo, Japan, reg. no. 8434.

interrogatorium Fischer-Piette, 1977: 21, pl.
2, fig. 2 [Laevicardium]. Recent; “Californie.”
Depository (holotype): Muséum National
d'Histoire Naturelle, Paris, France, reg. no. ?.
A juvenile specimen. It is possible that the
type-locality is given erroneously. Synonym of
Keenocardium californiense (Deshayes,
1839).

iwasiroense Nomura, 1935: 113, pl. 6, figs.
1, 2 (holotype not designated) [Cardium
(Cerastoderma)]. Hitosao, Ogino District
along the Agano-gawa, Fukushima Prefec-
ture, Honshu; Hitosao Formation, Upper
Miocene. Depository (holotype): Saito Ho-on
Kai Museum, Sendai, Japan, reg. no. 2146.

kljutschiense Krishtofovich, 1969: 191, pl.
4, figs. 1 (holotype), 2, 3 [Clinocardium).
Goryachie Kljuchi, Tjushevskaya River,
Kronotskij District, Eastern Kamchatka;
“Goryachikh Kljuchej” suite, Middle Miocene.
Depository (holotype): Central Research
Geological Prospecting Museum, Leningrad,
U.S.S.R. reg. по. 59/6780.

lispum Roth & Talmadge, 1975: 3, text-fig.
1a (holotype), 1b [Clinocardium]. Off the U.S.
Highway 101 bridge over Eel River, Humboldt
County, California; Rio Dell formation, Plio-

310 KAFANOV

cene. Depository (holotype): Museum of
Paleontology, University of California, Berke-
ley, U.S.A., reg. no. 14152.

okushirense Uozumi & Fujie, 1966: 150,
pl. 12, figs. 4 (holotype), 5, 6 [Clinocardium].
Cliff along the river, about 400 m upper
stream from the Miyatsu-gawa, Miyatsu,
Okushiri Island, Southwest Hokkaido;
Tsurikake Formation, Miocene. Depository
(holotype): University of Hokkaido, Sapporo,
Japan, reg. no. 13732.

praeblandum Keen, 1954: 15, pl. 1, figs. 6
(holotype), 1, text-figs. 5-6 [Clinocardium].
West end of Las Trampas Ridge near Walnut
Creek, Concord Quadrangle, Contra Costa
County, California; Briones formation, Upper
Miocene. Depository (holotype): Museum of
Paleontology, University of California, Berke-
ley, U.S.A., reg. no. 14836.

pristinum Keen, 1954: 16, pl. 1, figs. 15
(holotype), 9, text-figs. 7 (holotype), 8
[Clinocardium]. Southwest part of Shell
Ridge, near Walnut Creek, Concord Quad-
rangle, Contra Costa County, California; San
Pablo group, Neroly Formation (?), Upper
Miocene. Depository (holotype): Museum of
Paleontology, University of California, Berke-
ley, U.S.A., reg. no. 14838.

pseudofossile Reeve, 1845, sp. 52, pl. 10
[Cardium]. Recent; [Kamchatka] (type-locality
here designated). Depository (syntypes): Brit-
ish Museum (Natural History), London, Great
Britain, reg. no. 1975617. Synonym of Keeno-
cardium californiense (Deshayes, 1839).

subdecussatum Shuto, 1960: 216, pl. 25,
figs. 12 (holotype), 9, 10, 20, text-fig. 1c
[Clinocardium]. Yamaji, Mino-mura, Koyu
District, Miyazaki Prefecture; Kyushu;
Miyazaki group, the lowest part of the Tsuma
member, Upper Miocene. Depository (holo-
type): Department of Geology, Faculty of Sci-
ences, Kyushu University, Fukuoka, Japan,
reg. no. 4777.

californiense uchidai Habe, 1955: 11, pl.
2, figs. 5, 6 [Clinocardium uchidai]. Recent;
Akkeshi Bay, Hokkaido. Depository (holo-

type): National Science Museum, Tokyo,
Japan, reg. no. 53378. This form name was
first published by Kira (1954: 111, pl. 55, fig.
1), where “Clinocardium uchidai Habe, MS”
was illustrated without a formal description;
Kira s specific name is therefore a nomen
nudum.

vulva Jousseaume, 1898: 81 [Сагашт].
Recent; “Japon.” Depository (holotype):
Museum National d'Histoire Naturelle, Paris,
France, reg. no. ?. Synonym of Keeno-
cardium californiense (Deshayes, 1839) fide
Fischer-Piette, 1977, pl. 11, fig. 4.

Genus Ciliatocardium Kafanov, 1974

Ciliatocardium Kafanov, 1974a: 1469.

Type-species: Cardium ciliatum Fabricius,
1780: Recent, Greenland (original designa-
tion).

Shell medium-sized (to 80 mm and more),
oval-rounded or truncated-trigonal, inequi-
lateral, moderately inflated. Beaks fairly high,
prosogyrate, elevated and curved. Ribs about
20-50 in number, often widely arranged on
the anterior valve surfaces. Ribs triangular or
tectate in cross-section. Crests of ribs with
longitudinal rows of thin ciliated periostracal
fringes (in poorly preserved fossil shells ribs
may be differently smoothed); small spiniform
(lobes) observed sometimes in juveniles on
crests of ribs. Anterior lower lateral tooth of
the right valve without longitudinal ridge on
dorsal surface. Lunula oblong and cordiform
or absent. Area if present narrow and lanceo-
late. Distal part of foot with narrow ventral
sulculus Surrounded on both sides by longi-
tudinal rows of delicate papillae. Labial palps
long but less than a half the length of the inner
demibranch.

Paleocene(?)-Eocene-Recent; northwest-
ern (south to Kyushu) and northeastern Pa-
cific (south to Washington). Arctic and North
Atlantic (south to Cape Cod, Iceland and
southern Norway; in Pliocene south to Eng-
land) (Fig. 7).

Key to the species and subspecies

1. Height of shell equal to or greater than length .................................... pet

Height of shell less than length .........
2. Average rib number 30 or more than 30
Average rib number fewer than 30 ......

3. Shell inequilateral (beaks near the anterior 0,40-0,41), somewhat oblique ..............

E ne ciliatum dawsoni (Stimpson, 1863).

Shell subequilateral (beaks near the anterior 0,44-0,45), not oblique ..................

y LITO NERO yakatagense (Clark, 1932).

4. Maximum size of adult shell more than 25 mm; shell trigonally ovate; average rib number

АО.

ИС hataii (Науазака, 1956).

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 311

a if à
Woe 7

ql Ne

023 0°
Is
AS NY
== A

IR Г

ay DT |
a Set

x urn!
eae NEI

FIG. 7. Geographical and geological distribution of Ciliatocardium. 1—Recent; 2—Palaeocene and Eocene:
3—Oligocene; 4—Miocene; 5—Pliocene; 6—Pleistocene.

Ie

18.

Maximum size of adult shell fewer than 25 mm; shell rounded;........................
averagemio numberrabout 282.) 20.7... SE tigilense (Slodkewitsch, 1938).
ENS criss lek IS. es oe ee a 6.
Averagernbänümbertewerithangor ven... RE See Rhee PRE (MA 14.
average herdht/lengih ratio more ап: 0,86 >.... 2228). Ses Поза Па 7e
Averageshieighi/lengthirationless than/0,85 „Mr nen El RE 12.
Maximum size’ of aduit«shell'more than 45 mimi > 2.2.2.2... A 8.
Maximumbsize*oraquit shelllless than’45 mma.) A TO eee 10.

. Average height/length ratio about 0,96; shell rather inequilateral ......................

RO O TE A LR ciliatum ciliatum (Fabricius, 1780).
Average height/length ratio about 0,98; shell subequilateral or equilateral ............ 9.

. Shell subequilateral (beaks near the anterior 0,44-0,45) .............................

te E DAS DRAC ee а: ciliatum chikagawaense (Kotaka, 1950).
Shell equilateral (beaks near the anterior 0,48-0,49) .................................
Г A A ciliatum pubescens (Couthouy, 1838).

. Average height/length ratio about 0,91-0,92 ............ asagaiense (Makiyama, 1934).
Average helight/length ratio more: than 0,94 12202 A ee A
Average mb inumberiabouti40 5.000.000... A E ainuanum (Yokoyama, 1927).
AVeradetnbinumber aboutiB5 | ле... Me A shinjiense (Yokoyama, 1923).
Е 4O0/ommorerininumber..22) 0.0%)... ee ermanensis (Sinelnikova, 1976).
OSOS MIN UNDER. I... ее Seat Io. meas. вое. LES

. Maximum size of adult shell more than 50 mm; average height/length ratio about 0,84 ..

NA OLAS ERAS IATA ees iwatense (Chinzei, 1959).
Maximum size of adult shell less than 50 тт; average height/length ratio about
POMPES. ПН rie р, A SN rose SENTE
EEE IN ss AA GU DRA на schmidti (Khramova, 1962).

HAveragesiheight/lengthiratior0:90.onimore : LAA. ASA AAA 15.
Averagesheight/lengihfratio.lessıthan.0,90 mo). ame keinen Bene a 7:
. Maximum size of adult shell less than 40 mm ............ yamasakii (Makiyama, 1934).
Maximumksize ofradult:shell/more: than: 40 плит. ож tao See 16.
mis aboute2anin numben daa dad... WR makiyamae (Kamada, 1962).
Ribs або 2-25 палитре want)... ud matchgarense (Makiyama, 1934).
Maximum size of adult shell more than 40 mm ............ uyemurai (Kanehara, 1937).
Maximum:;sizevofsaduli;shell less пап: 40 mme oh ah NME Sts CE 18.

Average height/length ratio about 0,83-0,84; maximum size of adult shell about 36 mm .
AI A NE: mm ADS hansen mutuense (Nomura 4 Hatai, 1936).
Average height/length ratio about 0,86; maximum size of adult shell about 15 mm ......
a A > A O su Mad er te snatolense (Krishtofovich, 1947).

SV
Described taxa

ainuanum Yokoyama, 1927b: 202, pl. 51,
figs. 7 (lectotype; designated by Hatai &
Nisiyama, 1952: 35), 5, 6 [Cardium]. Sanke-
betsu, Haboromachi, Tomamae District,
Teshio Province, Hokkaido; Haboro Forma-
tion, Lower or Middle Miocene. Depository
(lectotype): Geological Institute, University of
Tokyo, Tokyo, Japan, reg. no. ?.

arcticum Sowerby, 1841a: 106; 1841b: 2,
no. 27, fig. 26 [Cardium]. Recent; “Arctic
Seas.” Depository (possible syntypes): British
Museum (Natural History), London, Great
Britain, reg. no. 1975618. Synonym of Cilia-
tocardium ciliatum (Fabricius, 1780).

asagaiense Makiyama, 1934: 139, pl. 5,
figs. 23 (holotype), 20, 22 [Cardium (Ceras-
toderma)]. Taira, Yotsukura, мак District,
Fukushima Prefecture, Honshu; Shiramizu
group, Asagai Formation, Oligocene. Deposi-
tory (holotype): Institute of Geology and Min-
eralogy, Kyoto University, Kyoto, Japan, reg.
no. 350011.

? brooksi Clark, 1932: 812, pl. 18, fig. 5
[Cardium (Papyridea)] non MacNeil in
MacNeil, Mertie & Pilsbry, 1943: 91, pl. 15, fig.
14 [Cardium (Cerastoderma)]. Yakataga Dis-
trict (about 60°N), Gulf of Alaska; Poul Creek
Formation, Upper Oligocene-Lower Miocene.
Depository (holotype): Museum of Paleon-
tology, University of California, Berkeley,
U.S.A., reg. no. 30402.

ciliatum chikagawaense Kotaka, 1950:
46, pl. 5 figsuá, 2,5. (holotype) 13, 47:16
[Clinocardium chikagawaense]. The sea cliff
at the outlet of Chikagawa River at Chika-
дама, Tanabu-machi, Shimokita District,
Aomori Prefecture, Honshu; Hamada Forma-
tion, Pliocene. Depository (holotype): Institute
of Geology and Paleontology, Tohoku Univer-
sity, Sendai, Japan, reg. no. 72999.

ciliatum Fabricius, 1790: 410 [Cardium].
Recent; Greenland [possibly southwestern
coast]. Depository (lectotype: here designat-
ed): Universitetets Zoologiske Museum,
Kpbenhavn, Denmark, reg. no. ?. Recent rec-
ords: North Pacific (South to Korea, Hokkaido,
Boso Peninsula, Honshu, Aleutian and Com-
mander Islands and Puget Sound, Washing-
ton), North Atlantic (south to southern Nor-
way, south Iceland, south Greenland and
Cape Cod, Massachusetts) and Arctic Seas.
(Fig. 7). Fossil records: lower part of Maru-
yamskaya Suite of Sakhalin (Middle Miocene),
Komeutiyamskaya suite to Koryak Plateau
(Upper Miocene), Utsutoge Formation of

KAFANOV

Honshu (Upper Miocene), Okobykajskaya
suite of Northern Sakhalin (Upper Miocene),
upper part of Limimtevayamskaya and Ustj-
Limimtevayamskaya suites of Karaginskij
Island (Pliocene), Alekhinskaya and Kamuj-
skaya suites of Kurile Islands (Upper Mio-
cene), Pliocene Golovinskaya suite of Kurile
Islands, Setana Formation of Hokkaido, Kubo,
Sawane and Shigarami formations of
Honshu, Beringian Pliocene of Alaska and
Pribiloff Islands, Upper Pliocene and Pleisto-
cene of Iceland (Tjornes Crag, zone of
Serripes groenlandicus), Chukotka (Pina-
kuljskaya suite), Iceland (Furuvik and Brejda-
vik), England (сетап Crag) and Petchora
Lowland (Kolvinskaya suite). One of the most
widely distributed species in Quaternary de-
posits of Arctic and Subarctic.

comoxense Dall, 1900: 1093 [Cardium].
Vancouver Island, British Columbia; Pleisto-
cene. Depository (lectotype): U.S. National
Museum, Washington, D.C., U.S.A., reg. no.
427772. For figure of lectotype see: Keen,
1954: pl. 1, figs. 5, 7, 8. Synonym of Ciliato-
cardium ciliatum (Fabricius, 1780).

ciliatum dawsoni Stimpson, 1863: 58,
text-fig. [Cardium dawsoni]. Hope Саре,
southeastern coast of Hudson Bay, Canada;
Pleistocene (?). Depository: unknown.

ermanensis Sinelnikova in Sinelnikova,
Fotjanova, Chelebaeva et al., 1976: 38, pl. 6,
fig. 18, 1 [Clinocardium]. Near Enemten
Rocks, Tigiljskij District, western Kamchatka;
the lowest part of Ermanovskaya suite, Upper
Miocene. Depository (holotype): Geological
Institute of the U.S.S.R. Academy of Sci-
ences, Moscow, U.S.S.R., reg. по. 366/388.

hataii Hayasaka, 1956: 18, pl. 2, figs. 3a—b
[Clinocardium]. Cliff of the Takesegawa River
west of Takakura, Futaba District, Fukushima.
Prefecture, Honshu; Ishiguma Formation,
Pliocene. Depository (holotype): Institute of
Geology and Paleontology, Tohoku Univer-
sity, Sendai, Japan, reg. no. 77375.

hayesii Stimpson, 1864: 142 [Сагашт].
Recent; Disko Island, southwestern Green-
land. Depository: unknown. Synonym of
Ciliatocardium ciliatum (Fabricius, 1780).

icelandicum Reeve, 1845: sp. 54, pl. 11
[Cardium]. Recent; Iceland. Erroneously pro
islandicum Bruguière, 1789. Synonym of
Ciliatocardium ciliatum (Fabricius, 1780).

islandicum Вгидшеге, 1789: 222 [Cardium]
ex Chemnitz, 1782: 200, pl. 19, figs. 195, 176,
nonbinom. (Official index . .., 1958: 5, Direc-
tion 1). Recent; Iceland. Depository (syn-
types): Universitetets Zoologiske Museum,

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 313

Kpbenhavn, Denmark, reg. no. ?. Synonym of
Ciliatocardium ciliatum (Fabricius, 1780).

iwatense Chinzei, 1959: 125, pl. 11, figs. 9
(holotype), 10 [Clinocardium]. Near Ochiai,
Kintaichi-mura, Ninohe District, lwate Pre-
fecture, Honshu; Sannohe group, Kubo For-
mation, Pliocene. Depository (holotype): Insti-
tute of Geology, Faculty of Science, University
of Tokyo, Tokyo, Japan, reg. no. 8572.

makiyamae Kamada, 1962: 104, pl. 10,
figs. 18 (holotype), 19-21 [Clinocardium
asagaiense makiyamae]. Nabezuka, Hirono-
machi, Joban coal-field, Honshu; Asaga For-
mation, Oligocene. Depository (holotype): In-
stitute of Geology and Paleontology, Tohoku
University, Sendai, Japan, reg. no. 15800. For
taxonomic notes see: Kafanov, 1974a: 1470.

matchgarense Makiyama, 1934: 137, pl. 5,
figs. 31 (holotype), 30 [Cardium (Cerasto-
derma). Shore of Cape Marie, near Matchi-
gar, Schmidt Peninsula, Northern Sakhalin;
“Marie Formation” [Vengerijskaya suite], Up-
per Oligocene. Depository (holotype): Insti-
tute of Geology and Mineralogy, Kyoto Uni-
versity, Kyoto, Japan, reg. no. 100007.

mutuense Nomura 8 Hatai, 1936: 279, pl.
33, fig. 11 [Cardium (Clinocardium)]. Koma-
tazawa, Aiuti-mura, Mutu Province, Honshu;
Isomatsu Formation, Oligocene. Depository
(holotype): Saito Ho-on Kai Museum, Sendai,
Japan, reg. no. 8799.

padimeicum Merklin & Zarkhidze in Merk-
lin, Zarkhidze & llyina, 1979: 44, pl. 7, figs.
10 (holotype), 11 [Clinocardium ciliatum].
Nadejtyvis River, Padimejskaya suite, Pleis-
tocene. Depository (holotype): Paleontologi-
cal Institute of the U.S.S.R. Academy of Sci-
ences, Moscow, U.S.S.R., reg. no. 2700/76.
Synonym of Ciliatocardium ciliatum (Fabric-
ius, 1780).

ciliatum pubescens Couthouy, 1838: 61,
pl. 3, fig. 6 [Cardium pubescens]. Recent;
Massachusetts Bay. Depository: unknown.

? sachalinense Khramova, 1962: 437, pl.
1, figs. 6 (holotype), 7 [Clinocardium]. Keton
River, Poronajskij District, South Sakhalin;
lower part of Kurasijskaya suite, Middle
Miocene. Depository (holotype): All-Union Oil
Research Geological Institute, Leningrad,
U.S.S.R., reg. no. 659/46.

salvationemense Lautenschläger in
Khramova, 1962: 438, pl. 1, figs. 8 (holotype),
9-12 [Clinocardium]. Cape Spassennyj, Tatar
Strait coast, Alexandrovskij District, Western
Sakhalin; Gennojshinskaya suite, Oligocene.

Depository (holotype): Central Research
Geological Prospecting Museum, Leningrad,

U.S.S.R., reg. no. 84/6197. Synonym of
Ciliatocardium asagaiense (Makiyama,
1934).

schmidti Khramova, 1962: 436, pl. 1, figs.
1 (holotype), 2, 3 [Clinocardium]. North coast
of Schmidt Peninsula west of Matchigar Lake,
Northern Sakhalin; middle part of Matchigar-
skaya suite, Upper Oligocene. Depository
(holotype): All-Union Oil Research Geological
Institute, Leningrad, U.S.S.R., reg. no.
659/24.

shinjiense Yokoyama, 1923: 7, pl. 2, figs.
6a-b [Cardium]. Fujina, Tamayu-mura,
Yatsuka District, Shimane Prefecture,
Honshu; Fujina Formation, Middle Miocene.
Depository (holotype): Geological Institute,
University of Tokyo, Tokyo, Japan, reg. no. ?

snatolense Krishtofovich, 1947: 74, pl. 8,
fig. 7 [Cardium (Acanthocardia) snatolensis].
Sea cliff southwest of the mouth of the
llinushka River, Western Kamchatka; upper
part of Tigiljskaya series, Oligocene. Deposi-
tory (holotype): Central Research Geological
Prospecting Museum, Leningrad, U.S.S.R.,
reg. no. 78/5610.

tigilense Slodkewitsch, 1938: 380, pl. 74,
figs. 10, 10a [Laevicardium(?)]. Near the
mouth of the Polovinnaya River, western
Kamchatka; lower part of Kavranskaya Suite,
Upper Miocene. Depository (holotype): Cen-
tral Research Geological Prospecting Mu-
seum, Leningrad, U.S.S.R., reg. по.
914/5060.

uyemurai Kanehara, 1937: 175, text-figs.
6-8 [Cardium (Cerastoderma)]. "Great
Fuhdji, North Karafto” [Boljshaya Khudi River,
Pogranichnyj District], southeastern part of
North Sakhalin; “sandy shale of the Congi
Series” [Pliocene]. Depository: “Geological
Survey of Japan.”4

yakatagense Clark, 1932: 813, pl. 18, fig. 8
[Cardium (Cerastoderma)], Yakataga District
(about 60°N), Gulf of Alaska; upper part (?) of
the Poul Creek Formation, Lower Miocene
(?). Depository (holotype): Museum of Pale-
ontology, University of California, Berkeley,
U.S.A., reg. no. 30384.

yamasakii Makiyama, 1934: 138, pl. 5,
figs. 23 (holotype), 24 [Cardium (Cerasto-
derma)]. Shore of Cape Marie, near Matchi-
gar, Schmidt Peninsula, northern Sakhalin;
“Marie Formation” [Vengerijskaya suite], Up-
per Oligocene. Depository (holotype): Insti-

4 According to Hatai & Nisiyama (1952), all collections from the Geological Survey of Japan were totally destroyed during the

World War Il.

314 KAFANOV

FIG. 8. Geographical and geological distribution of Profulvia. 1—Oligocene; 2—Miocene; 3—Pliocene.

tute of Geology and Mineralogy, Kyoto Uni-
versity, Kyoto, Japan, reg. no. 100005.

Tribus Profulviini Kafanov in
Kafanov & Popov, 1977

Kafanov & Popov, 1977: 62

Shell carinate, gaping posteriorly or at both
ends. Radial ribs well developed, convex an-
teriorly, Curved on posterior part of valve.
Beaks nearly orthogyrate, weakly prosogyrate
or opisthogyrate.

Oligocene-Pliocene; northwestern Pacific
and Alaska (Fig. 8).

Genus Profulvia Kafanov, 1976

Profulvia Kafanov, 1976: 111.

Type-species: Papyridea harrimani Dall,
1904; Unga conglomerate, lower part of Mid-
dle Miocene, Popov Island, Alaska Peninsula
(Original designation).

Shell medium-sized or fairly large (about
100 mm and more), elongate-ovate, truncat-
ed, variably inequilateral, moderately convex,
frequently carinate, with gape at posterior or
both ends. Beaks relatively low, obtuse,

weakly prosogyrate, nearly orthogyrate or
opisthogyrate. Ribs about 30-65 in number.
Ribs straight, narrow and low on the anterior
valve surfaces, more curved posteriorly. Ribs
convex anteriorly (Fig. 4b); their height and
width increase and flattened intercostal
spaces become deeper posteriad. Ribs fre-
quently reduced on the posterior slope. Ribs
rounded or triangular in cross-section, or
combination of these two types observed: 1)
ribs are low and rather rounded in cross-sec-
tion on the anteror valve surface and 2) ribs
are high, irregularly triangular with abrupt
posterior wall and more sloped anterior wall
on the posterior valve surfaces. Ridges of ribs
with numerous commarginal lines, wrinkles
and growth lines; weak nodes occur where
growth lines cross costal crests. Dental mar-
gin weakly curved. Paired cardinal teeth small
and straight in both valves; lateral teeth usu-
ally single. Lunula and escutcheon areas
weak. Internal valve surfaces or at least their
ventral part with distinct indentations and
ventral margin serrated.

Geographical and geological distribution as
in the tribus (Fig. 8).

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 315

Key to the species

IsAveragesheighl/lengin:.ratio,abou%0;8340r.lESS: 2... = cic see Sea А o ee 2:
Averagerheight/lengih:rauo more MANO AR аи 9.
Рахит ме onadult:shelllessetham ИО ee нано 3:
Maximum: size oiaduit Shell morerthan:70!mmi Oi 8.
3. Shell inequilateral (beaks near the anterior 0,37-0,38) sertunayana (Slodkewitsch, 1938).
Shell subequilaeral (beaks near the anterior 0,42-0,44) ............................ 4.
AS ЗО CNE aie ite ha ua ttes CLS ack aes ie A ca eet PE eee CL SN
EROS MIAO CUA Rha cate TN as pl TT MENO MATO CAN CM EEE 6.
5. Average height/length ratio about 0,81; ribs 36-37 ...... angulata (Slodkewitsch, 1938).

Average height/length ratio about 0,75; ribs 32-33 .... noyamiana (Slodkewitsch, 1938).
6. Average height/length ratio about 0,82-0,83; ribs 4045 .............................

Nas utcholokensis (Slodkewitsch, 1938).

Average height/length ratio about 0,70-0,77; ribs more than 45 ................... de
7. Average height/length ratio about 0,70; maximum size of adult shell about 55 mm......

ASS: kurodai (Hatai & Nisiyama, 1952).

Average height/length ratio about 0,75-0,77; maximum size of adult shell about 35 mm .

SEN aa le kovatschensis (llyina, 1962).

8. Shell subequilateral (beaks near the anterior 0,41-0,42); ribs 50-60 ...................

РЕ matschigarica (Khomenko, 1938).

Shell strongly inequilateral (beaks near the anterior 0,32); ribs 36-40 ..................

ETICA securiformis (Slodkewitsch, 1938).

9 Average height/length ratio about .0,90=0.92 emma co teo ase ct 10.
Average height/length ratio about 0,85-0,86 2: 02. o la poca hl:
10. Ribs 40-45; maximum size of adult shell about 90 mm . kipenensis (Slodkewitsch, 1938).
Ribs 60 or more; maximum size of adult shell about 50 mm ..........................

фене або зо и аитавегв 2.2... ne.
Ribs about 40-45 in number ............

angulata Slodkewitsch, 1938 (ex Kogan,
MS): 404, pl. 81, figs. 8, 8a [Papyridea]. Be-
tween the mouths of Noyami and Мау]
Sertunaj Rivers, western Sakhalin; “Rykhlaya
suite” [Sertunajskaya and Alexandrovskaya
suites], lower Middle Miocene. Depository
(holotype): Central Research Geological
Prospecting Museum, Leningrad, U.S.S.R.,
reg. no. 180/5294.

hamiltonense Clark, 1932: 813, pl. 18,
figs. 7 (holotype), 6,10 [Cardium (Serripes)].
Yakataga District (about 60°N), Gulf of
Alaska; Poul Creek Formation (?), Upper
Oligocene(?)-Lower Miocene (Addicott, 1971;
Addicott et al., 1971). Depository (holotype):
Museum of Paleontology, University of Cali-
fornia, Berkeley, U.S.A., reg. no. 30405.

harrimani Dall, 1904: 114, pl. 10, fig. 5
[Papyridea]. North coast of Popov Island,
Alaska Peninsula; Bear Lake Formation,
Unga conglomerate, lower Middle Miocene,
Depository (holotype): U.S. National Mu-
seum, Washington, D.C., U.S.A., reg. no.
164867.

kipenensis Slodkewitsch, 1938: 409, pl.
82, figs. 2 (holotype), 1, pl. 83, figs. 1-3

SR RE nn hamiltonense (Clark, 1932).
Mut ENT sakhalinensis (Slodkewitsch, 1938).
A u: harrimani (Dall, 1904).

[Papyridea]. 18km from the mouth of the
Snatol River, western Kamchatka; upper part
of the Kavranskaya series [Upper Miocene].
Depository (holotype): Central Research
Geological Prospecting Museum, Leningrad,
U.S.S.R., reg. no. 902/5060.
kovatschensis llyina, 1962: 343, pl. 2, figs.
8, 8a [Papyridea]. Utkholok Cape, western
Kamchatka; “Tufogennyj horizon,” lower part
of Voyampoljskaya series, Oligocene. De-
pository (holotype): Central Research Geo-

logical Prospecting Museum, Leningrad,
U.S.S.R., reg. no. 121/6068.
kurodai Hatai & Nisiyama, 1952: 105

[Papyridea (Fulvia)] pro Papyridea (Fulvia)
nipponica Yokoyama, 1926c: 294, pl. 34, fig.
16 non 1924: 17, pl. 3, figs. 3, 4. Sawane,
Sado Island, Niigata Prefecture, Honshu;
Sawane formation, Lower Pliocene. Deposi-
tory (holotype): Geological Institute, Univer-
sity of Tokyo, Tokyo, Japan, reg. no. ?.
matschigarica Khomenko, 1938: 47, pl. 7,
figs. 5 (lectotype), 6, 7, pl. 8, fig. 6, pl. 9, fig. 7
[Papyridea]. Between the Marie Cape and
Matchigar Lake, Schmidt Peninsula, northern
Sakhalin; lower part of the Machigarskaya

316 KAFANOV

suite, Oligocene. Depository (lectotype):
Central Research Geological Prospecting
Museum, Leningrad, U.S.SR. reg. no.
81/5044. For figure of lectotype see: Slodke-
witsch, 1938, pl. 84, fig. 2.

nipponica Yokoyama, 1924: 17, pl. 3, figs.
3, 4 [Papyridea (Fulvia)]. Tatsuta coal-field,
Futaba District, Fukushima Prefecture, Hon-
shu; Asagai Formation, Oligocene. Deposi-
tory (holotype): Geological Institute, Univer-
sity of Tokyo, Tokyo, Japan, reg. no. ?. Fol-
lowing Hatai & Nisiyama (1952) and
Makiyama (1957), the author considers this
form a synonym of Profulvia harrimani (Dall,
1904).

noyamiana Slodkewitsch, 1938 (ex Kogan,
MS): 413, pl. 86, figs. 3 (holotype), 2
[Papyridea]. Between the mouths of Noyami
and Malyj Sertunaj Rivers, western Sakhalin;
“Rykhlaya suite” [Sertunajskaya and Alex-
androvskaya suites], lower Middle Miocene.
Depository (holotype): Central Research
Geogical Prospecting Museum, Leningrad,
U.S.S.R., reg. no. 181/5294.

sakhalinensis Slodkewitsch, 1938 (ex
Kogan, MS): 412, pl. 86, fig.1 [Рарупаеа].
Between the mouths of Noyami and Мау]
Sertunaj Rivers, western Sakhalin; “Rykhlaya
suite” [Sertunajskaya and Alexandrovskaya
suites], lower Middle Miocene. Depository
(holotype): Central Research Geological
Prospecting Museum, Leningrad, U.S.S.R.,
reg. no. 182/5294.

securiformis Slodkewitsch, 1938: 411, pl.
85, fig. 1 [Papyridea]. Kovachina Bay, west-
ern Kamchatka; lower part of Kavranskaya
series, Middle Miocene. Depository (holo-
type): Central Research Geological Prospect-
ing Museum, Leningrad, U.S.S.R., reg. no.
899/5060.

sertunayana Slodkewitsch, 1938 (ex
Kogan, MS): 405, pl. 82, figs. 3, 3a [Papyri-
dea]. Between the mouths of Noyami and
Maly} Sertunaj Rivers, Western Sakhalin;
“Rykhlaya suite” [Sertunajskaya and Alex-
androvskaya Suites], lower Middle Miocene.
Depository (holotype): Central Research
Geological Prospecting Museum, Leningrad,
U.S.S.R., reg. no. 185/5294.

utcholokensis Slodkewitsch, 1938: 403,
pl. 82, figs. 6 (holotype), 4, 5 [Рарупаеа].
Utcholok Cape, western Kamchatka; lower
part of Vayampoljskaya series, Oligocene.

Depository (holotype): Central Research
Geological Prospecting Museum, Leningrad,
U.S.S.R., reg. no. 911/5060.

Tribus Serripedini Kafanov, 1975

Kafanov, 1975: 147.

Radial ribs obsolete or absent but their
traces can usually be observed on the poste-
rior and rarely on the anterior valve surfaces.
Hinge weak due to reduction of cardinal teeth.

Early Oligocene-Recent; northwestern Pa-
cific south to south Honshu and northeastern
Pacific south to Puget Sond, Arctic Seas and
North Atlantic (South to Cape Cod, Iceland
and south Norway; in later Pliocene and Early
Pleistocene to England and to the Nether-
lands) (Figs. 9, 10).

Genus Serripes Gould, 1841 ex Beck, MS

Aphrodite Lea, [1837]: 111 non Leske,
1775, nec Link, 1807 (pro Aphrodita Linne,
1758), nec Hubner, [1819], nec Lendenfeld,
1886;

Aphrodita Leach in Sowerby, 1839: 70 (pro
Aphrodite Lea, 1837 non Linne, 1758);

Acardo Swainson, 1840: 374 non Lamarck,
1799, nec Roissy, 1805, nec Mühlfeldt, 1811,
nec Menke, 1828, nec Herrmannsen, [1846];

Serripes “Beck” Gould, 1841: 93.

Type-species: Cardium groenlandicum

Bruguiere, 1789; Recent, Greenland (by
monotypy).
Shell medium-sized or fairly large (to

90 mm and more), flattened, oblong-elliptical
or truncate-trigonal, variously inequilateral; as
a rule, anterior and broader than posterior
one. Posterodorsal margin smoothly joined
with the posterior valve margin. Carina on the
posterior valve surface obsolete. Beaks
moderately prosogyrate or nearly ortho-
gyrate. Radial ribs almost entirely reduced.
Hinge strongly reduced, frequently teeth
completely absent. Bases of the anterior
lower lateral teeth lie on outer side of the in-
ternal branches of hinge margin (Fig. 3a). Dis-
tal part of foot with longitudinal row of crests
or denticles, ventral sulculus absent. Labial
palps long and nearly equal in length to inner
demibranch.

Geographical and geological distribution as
in the tribus (Fig. 9).

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 317

FIG. 9. Geographical and geological distribution of Serripes. 1—Recent. 2—Oligocene; 3—Miocene; 4—
Pliocene; 5—Pleistocene.

Key to the species and subspecies

. Traces of radial ribs well developed on the medial valve surfaces ....................

Ns Re AS E ео. MMe shiobaraensis Noda, 1962.
Traces of radial ribs not developed on the medial valve surfaces ................... as

. Posterior valve margin almost straight; cardinal teeth not reduced .....................

ee eh A A ES groenlandicus fabricii (Deshayes, 1855).

Posterior valve margin variously curved; cardinal teeth variously reduced ............ $:
. Average length of adult shell more than 100 тт; shell much swollen; traces of radial ribs
observed only on the anterior valve surfaces ............... expansus Hirayama, 1954.
Average length of adult shell less than 100 mm; shell variously inflated; traces of radial ribs
present, asa rule, on the posterior valve surfaces". "AMAR Tee ee 4.
MécignrilengthfrationmorerthantO 96... 5
Ficighwilengi ratiolless Капо: sro... . Asta. a, ese EP EE 9.
. Average height/length ratio about 1,20 .................... тигай Noda & Tada, 1968.
Average height/length ratio about 0,99-1,10 "NS елена: 6.

. Maximum size of adult shell about 95 mm; shell rather inequilateral (beaks near the anteror

OR OMAN AS een ее kamtschaticus llyina, 1963.
Maximum size of adult shell about 60 mm; shell subequilateral or nearly equilateral .. 7.
Shell nearly equilateral (beaks near the anterior 0,48); average height/length ratio about

VO CON PEU ВОИ OO BU. LCR tote totes tartare hataii Noda, 1962.
Shell subequilateral (beaks near the anterior 0,44-0,46); average height/length ratio about
Th UC) RE ATAR a Eee re 8.
Shellkikigonaliimioutliinemre... Mm rs. PORT. TYPE triangularis Noda, 1962.
SECA e tee EEE EP RS RER ee nodai Kafanov nom. nov.
Average height/length ratio more than 0,90 ...................................... 10.
Average height/length ratio less than 0.90 ....................................... il:
. Shell inequilateral (beaks near the anterior 0,39-0,40); average length of adult shell about
ESTER О A E ПО. ES A ochotensis Ilyina, 1963.
Shell rather inequilateral (beaks near the anterior 0,42); average length of adult shell about
SOMMEIL, FOUR PURES. сай squalidus (Yokoyama, 1924).

. Average height/length ratio about 0,75; maximum size of adult shell about 25mm......

EN TEEN EN A RE. LCR ARE res uvutschensis Пупа, 1963.
Average height/length ratio more than 0,78; maximum size of adult shell more than 40 mm
И Fe ne URES Rie. o A eine EE CE SSE 12

318 KAFANOV

12. Shell strongly inequilateral (beaks near the anterior 0,37-0,38)

... Japonica Noda, 1962.

Shell subequilateral or nearly equilateral (beaks near the anterior 0,44-0,48)........ Wes
13. Average height/length ratio about 0,87-0,88; shell subequilateral (beaks near the anterior

О see CS ee

RTE ve à groenlandicus (Bruguière, 1789).

Average height/length ratio about 0,80-0,81; shell nearly equilateral (beaks near the

anterior iva ado lios RL ee

Described taxa

album Verkrüzen, 1877: 53 [Cardium
(Aphrodite) groenlandicum var.]. Recent;
Newfoundland Bank. Depository: unknown.
Synonym of Serripes groenlandicus groen-
landicus (Bruguière, 1789) or Serripes groen-
landicus fabricii (Deshayes, 1854).

boreale Reeve, 1845: sp. 131, pl. 22
[Cardium] non Broderip & Sowerby, 1829:
369. Recent; Greenland. Depository (holo-
type): British Museum (Natural History), reg.
no. 1879.2.26.235. Synonym of Serripes
groenlandicus (Bruguiére, 1789).

columba Lea, 1834: 111, pl. 18, fig. 54
[Aphrodite]. Type-locality not given, nor was it
given subsequently; Lea listed only
“Hab..."; оп р. 111-112 under Remarks he
said: “lts habitat | am not acquainted with,
having purchased my specimens at a dealer's
in Europe, who could not inform me from what
country they came.” Depository: unknown.
Synonym of Serripes groenlandicus groen-
landicus (Bruguiere, 1789).

edentulum Montagu, 1808: 29 [Cardium
edentula] non Fleming, 1813: 92 nec
Deshayes, 1838: 57, pl. 3, fig. 3-6 [Cardium].
Recent; “on the shore near Portsmouth, after
a storm.” Depository: Exeter Museum, Exeter,
Great Britain (?). Synonym of Serripes groen-
landicus groenlandicus (Bruguiére, 1789).

expansus Hirayama, 1954: 66, pl. 4, figs. 1
(holotype), 2 [Serripes]. Nanatsuishi,
Oyamada-shimogo, Oyamada-mura, Tochigi
Prefecture, Honshu; Kobana Formation,
Lower Miocene. Depository (holotype): Tokyo
University of Education (Kyoiku Daigaku),
Tokyo, Japan, reg. no. 10136.

groenlandicus fabricii Deshayes, 1855:
333 [Cardium fabricii]. Recent; Iceland. De-
pository (holotype): Zoological Institute of the
U.S.S.R. Academy of Sciences, Leningrad,
U.S.S.R., reg. по. 1/13460. For figure of holo-
type, see Middenforff, 1849: pl. 16, figs. 6, 7.

fujinensis Yokoyama, 1923: 5, pl. 2, figs.
2a-b [Mactra]. Matsue, Fujina, Tamayu-
mura, Yatsuka District, Shimane Prefecture,
Honshu; Fujina Formation, Middle Miocene.
Depository (holotype): Geological Institute,

A as MES laperousii (Deshayes, 1839).

University of Tokyo, Tokyo, Japan, reg. no. ?
Unlike Noda (1962), the author considers this
form a synonym of Serripes groenlandicus
(Bruguière, 1789) rather than of $. /aperousii
(Deshayes, 1839) because of the general
valve outlines, their considerable convexity
and significantly elevated beaks.
groenlandicus Bruguière, 1789: 222 ex
Chemnitz, 1782: 202, pl. 19, fig. 198, non-
binom. (see: Official Index... 1958: 5, Direc-
tion 1) [Cardium]. Recent; [southeastern]
Greenland (here limited; Chemnitz reports
that the majority of representatives of this
species was collected for him from Juliane-
hob). Depository (possible syntypes): Univer-
sitetets Zoologiske Museum, Kébenhavn,
Denmark, reg. nos. ? Recent records: North
Pacific (south to central parts of Honshu,
Korea?, Peter the Great Bay, Aleutian and
Commander Islands and Puget Sound,
Washington), North Atlantic (south to Iceland,
southern Greenland and Cape Cod, Massa-
chusetis) and epicontinental Arctic Seas.
Fossil records: Miocene Echinskaya suite of
Chukotka, Yakataga formation of Alaska,
Undal-Umenskaya suite of Koryak Plateau,
Pestrotsvetnaya and Yunjunjvayamskaya
suites of Keraginskij Island, llyinskaya, Eto-
lonskaya, Kuluvenskaya, Goryachikh Klyu-
спе] and Nachikinskaya suites of Kamchatka,
Alekhinskaya, Kamujskaya and Okruglov-
скауа Suites of Kurile Islands, Uglegorskaya,
Sertunajskaya, Uranajskaya, Borskaya,
upper and middle parts of Maruyamskaya,
Ausinskaya, Kurasijskaya and Okobykajs-
кауа Suites of Sakhalin, Okada, Chijubetsu,
Magaribuchi, Sin-uryu, Wakkanai formations
of Hokkaido, Kobana, Fujina, Kurosawa,
Kanomatazawa, Ogino, Takahoko, Hongo
and Utsutoge formations of Honshu; Pliocene
Pinakuljskaya Suite of Chukotka, upper part of
Limimtevayamskaya and Ustj-Limimtevay-
amskaya suites of Karaginskij Island, Gavan-
skaya suite of Kamchatka, Golovinskaya,
Parusnaya and Okeanskaya suites of Kurile
Islands, upper part of Maruyamskaya, Maya-
mrafskaya, Matitukskaya and Pomyrskaya
suites of Sakhalin, Gobansoyama, Ebishima,
Rigashigawa, Sizun and Takinoe formations

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 319

of Hokkaido and Northern Honshu; Pliocene
and Plio-Pleistocene of Iceland (Tjornes Crag,
zone of Serripes groenlandicus), England
(Red Crag) and the Netherlands (Dutch Iceni-
an); Pleistocene sediments of Arctic and Sub-
arctic regions of the Northern Hemisphere.

? haboroensis Yokoyama, 1927b: 198, pl.
52, figs. 3 (lectotype; designated by Hatai &
Nisiyama, 1952: 86), 4 [Mactra]. Sankebetsu,
off Shinkukaku, Haboro-machi, Tomamae
District, Teshio Province, Hokkaido; Chiku-
betsu Formation, Lower Miocene. Depository
(lectotype): Geological Institute, University of
Tokyo, Tokyo, Japan, reg. no. ?. Shell form
closely resembles that of Serripes groen-
landicus (Bruguiere, 1789). The author can-
not refer this species with confidence to Ser-
ripedini for lack of data on hinge structure.

hataii Noda, 1962: 224, pl. 37, fig. 3
[Serripes]. lwaigawa, Kamikurosawa, Hagi-
hana-mura, Nishiiwai District, lwate Prefec-
ture, Honshu; lower part of the Nishikurosawa
Formation, Lower Miocene. Depository (holo-
type): Institute of Geology and Paleontology,
Tohoku University, Sendai, Japan, reg. no.
74593.

japonica Noda, 1962: 225, pl. 39, fig. 4
[Serripes]. Mukai, Sakekawa, Mogami Dis-
trict, Yamagata Prefecture, Honshu; Sake-
kawa Formation, Lower Pliocene. Depository
(holotype): Institute of Geology and Paleon-
tology, Tohoku University, Sendai, Japan,
reg. no. 78680.

kamtschaticus Пупа, 1963: 102, pl. 43,
figs. 2 (holotype), 3 [Serripes] sea cliff be-
tween the Moroshechnaya and Kovachina

Rivers, western Kamchatka; Etolonskaya
suite, upper Middle Miocene. Depository
(holotype): Central Research Geological

Prospecting Museum, Leningrad, U.S.S.R.,
reg. no. 24/96338.

laperousii Deshayes, 1839: 360; 1841b:
pl. 48 [Cardium]. Recent; Kadjak Island, Gulf
of Alaska (type-locality here designated; in
original description as type-locality are men-
tioned “Mers de Californie” but this species is
absent from the coast of California). Deposi-
tory: unknown. As fossil it was recorded from
Middle and Upper Miocene and Pliocene of
northeastern. and north Honshu and Hokkaido
(reviewed by Noda, 1962), from Upper Mio-
cene and Pliocene of Sakhalin and Kurile
Islands, but it should be noted that there is
much evidence that the fossil representatives
of this species in fact belong to Serripes
groenlandicus (Bruguière, 1789) and to other
species of the genus. It is unknown in
Neogene deposits of the northeastern Pacific.

muraii Noda & Tada, 1968: 202, pl. 22, fig.
22 [Serripes]. Small tributary of the Kakkonda
River, about 4 km NNW of the Takinoue Spa,
Shizukuishi-machi, lwate Prefecture, Honshu;
Yamatsuda Formation, upper Middle Mio-
cene. Depository (holotype): Institute of Geol-
ogy and Paleontology, Tohoku University,
Sendai, Japan, reg. no. 88058.

nodai Kafanov nom. nov. pro Cardium
pauperculum Yokoyama, 1923: 6, pl. 1, figs.
2а—с non Meek, 1871: 306 [Serripes]. Kami-
Ichiba, Shimane Prefecture, Honshu; Fujina
Formation, Middle Miocene. Depository (holo-
type): Geological Institute, University of
Tokyo, Tokyo, Japan, reg. no. ? For taxonom-
ic notes see: pauperculum Yokoyama, 1923.

ochotensis llyina, 1963: 102, pl. 42, figs. 2
(holotype), 1 [Serripes]. Sea cliff between the
Etolona River and Nepropusk Cape; Etolon-
skaya suite, Middle Miocene. Depository
(holotype): Central Research Geological
Prospecting Museum, Leningrad, U.S.S.R.,
reg. no. 248/6338.

pauperculum Yokoyama, 1923: 6, pl. 1,
figs. 2-c non Meek, 1871: 306, nec Yoko-
yama, 1925c: 121, pl. 14, figs. 12, 13 nec
1926b, 243, pl. 30, fig. 3 [Cardium], Kami-
Ichiba, Shimane Prefecture, Honshu; Fujina
Formation, Middle Miocene. Depository (holo-
type): Geological Institute, University of
Tokyo, Tokyo, Japan, reg. no. ? Following
Noda (1962), Keen (1973) considers this spe-
cies to be a synonym of Serripes groenlandi-
cus (Bruguière, 1789). Yokoyama described
and figured three different forms called Cardi-
um pauperculum: 1) the holotype, a speci-
men which slightly resembles Serripes hataii
Noda, 1962 and is much different in shell out-
lines from all Recent and fossil Serripes
groenlandicus (Bruguière, 1789); 2) a speci-
men from the Oligocene Akahira Beds of
Central Honshu described and figured by
Yokoyama (1925c, 121: pl. 14, figs. 12, 13) for
which Hatai & Nisiyama (1952: 39) suggest a
new name, Cardium arakawaense; 3) a spe-
cimen from the Upper Miocene Wakkanai
Formation of southwestern Honshu (Yoko-
yama, 1926b: 243, pl. 30, fig. 3) which really
may be identified with Serripes groenlandicus
(Bruguiere, 1789). Noda (1962) in comparing
Cardium pauperculum Yokoyama with
Serripes groenlandicus (Bruguiere, 1789) ap-
parently took into account the third form men-
tioned above, because he cites the name in
Yokoyama’s paper of 1926 in synonymy with
Serripes groenlandicus (Bruguière, 1789),
but he does not mention the original descrip-
tion and figure of Cardium pauperculum

320 KAFANOV

Yokoyama, 1923. Both Hatai and Nisiyama
(1952) do not give it. According to the author
the information does not justify the recognition
of Cardium pauperculum Yokoyama, 1923 as
a synonym of Serripes groenlandicus
(Bruguiere, 1789) and the species can retain
its rank of an independent species. However
owing to the presence of an older homonym,
Cardium pauperculum Meek, 1871, pauper-
culum Yokoyama, 1923 is given the new
name Serripes nodai in honour of the Japan-
ese paleontologist Prof. Hiroshi Noda.

protractus Dall, 1900: 11i2 [Serripes
groenlandicus var.]. Recent; type-locality not
given. Depository: unknown. Invalid name as
nomen infrasubsp. s.s.

radiata Donovan, 1803: pl. 161 et text, non

Spengler, 1802: 107 ([Mactra]. Recent;
“Langston Beach, near Portsmouth, after a
severe storm...’ Depository: unknown.

Synonym of Serripes groenlandicus groen-
landicus (Bruguière, 1789).

shiobaraensis Noda, 1962: 228, pl. 39, fig.
5 [Serripes]. Cliff facing the Hokigawa Electric
Power Station along the Hoki River, Sekiya,
Shiobara-machi, Shioya District, Tochigi Pre-
fecture, Honshu; Kanomatazawa Formation,
Middle Miocene. Depository (holotype): Insti-
tute of Geology and Paleontology, Tohoku
University, Sendai, Japan, reg. no. 78587.

squalidus Yokoyama, 1924: 16, pl. 3, figs.
1, la [Cardium (Laevicardium)]. Dodaira,
Misawa, Nakoso-shi, Fukushima Prefecture,
Honshu; lwaki Formation, Oligocene. Deposi-
tory (holotype): Geological Institute, Univer-
sity of Tokyo, Tokyo, Japan, reg. no. ?

titthus Krishtofovich, 1969: 192, pl. 4, figs.
4 (holotype), 5, 9, 12, 14 [Serripes]. Near the
mouth of the Talovaya River, Kronotskij Re-
servation, East Kamchatka; Tyushevskaya
suite, Middle Miocene. Depository (holotype):
Central Research Geological Prospecting
Museum, Leningrad, U.S.S.R., reg. no.
62/6780. Synonym of Serripes groenlandic-
us (Bruguiere, 1789).

triangularis Noda, 1962: 229, pl. 39, figs. 2
(holotype), 3 [Serripes]. Itanoki-sawa, Araki-
mura Mogami District, Yamagata Prefecture,
Honshu; Mitsumori Formation, Upper Mio-

cene. Depository (holotype): Saito Ho-on Kai
Museum, Sendai, Japan, reg. no. 8410.

unciangulare Khomenko, 1931: 75, pl.10,
fig. 21 [Cardium groenlandicum unciangu-
lare]. Boljshoj Garomaj River, east Kamchat-
ka; “Nadnutovskaya” suite, Pliocene. Syno-
nym of Serripes groenlandicus (Bruguière,
1789) as shown by original description: “Form
described here represents the extreme de-
gree of inequilaterality of lower forms of
Cardium groenlandicum. . . .” Moreover, ac-
cording to the faunal lists in Khomenko's pa-
per it frequently occurs together with the typi-
cal Serripes groenlandicus (Bruguiere,
1789).

uvutschensis Пупа, 1963: 76, pl. 25, fig. 5
[Serripes (?)]. Cliff of the Kovachina Bay near
the mouth of Moroshechnaya River; Ilyin-
skaya suite, Middle Miocene. Depository
(holotype): Central Research Geological
Prospecting Museum, Leningrad, U.S.S.R.
reg. no 103/6338.

Genus Yagudinella Kafanov, 1975

Yagudinella Kafanov, 1975: 147.

Type-species: Cardium (Serripes) notabile
Sowerby, 1915; Recent, Wakasa Bay,
Honshu (original designation).

Shell medium-sized or fairly large (to
100 mm and more), convex, truncated, obvi-
ously inequilateral. Anterior end much nar-
rower than posterior one. Posterodorsal mar-
gin passes into posterior valve margin at an
angle. Posterior valve surface, as a rule, with
pronounced carina. Beaks strongly inclined
forward and prosogyrate. Clear traces of the
radial ribs on the anterior and posterior valve
surfaces. Cardinal teeth somewhat reduced.
Bases of the anterior lower lateral teeth lie on
the ventral side of anterior part of hinge mar-
gin and their proximal parts extended postero-
dorsally toward beaks (Fig. 3b). Distal part of
foot with longitudinal row of closely spaced
combs but not denticles, which are high, in-
flated on the sides; ventral sulculus absent.
Labial palps long and near equal in length to
the inner demibranch.

Middle Miocene-Recent; northwestern
Pacific (South to southwestern Honshu).

Key to the species and subspecies

1. Shell hatchet-shaped in outline ...........
Shell triangular in outline ................

2. Shell strongly inequilateral (beaks near the anterior 0,38-0,39) ...................... or
Shell subequilateral (beaks near the anterior 0,41-0,48) ............................. 4.

SYSTEMATICS OF CLINOCARDIINAE KAFANOV 321

. Average height/length ratio about 0,94 ........ makiyamai makiyamai (Yokoyama, 1928).
Average height/length ratio about 0,83............ makiyamai nigamiensis (Noda, 1962).
. Average height/length ratio about 1,00; shell almost equilateral (beaks near the anterior

OLE. de ie en Be a notabilis notabilis (Sowerby, 1915).
Average height/length ratio about 0,81-0,82; shell subequilateral (beaks near the anterior

0,41)
Described taxa

makiyamai Yokoyama, 1928: 360, pl. 69,
fig.3[Mactra]. Nagaoka, River side at Hanzo-
gane, Hanzogane-mura, Koshi District,
Niigata Prefecture, Honshu; Ushigakubi For-
mation, Upper Miocene. Depository (holo-
type): Geological Institute, University of
Tokyo, Tokyo, Japan, reg. no. ?

makiyamai nigamiensis Noda, 1962: 227,
pl. 39, figs. 1a-€ [Serripes]. Nigami, Ooshima-
mura, Higashikubiki District, Niigata Prefec-
ture, Honshu; Shiiya Formation, Upper Mio-
cene. Depository (holotype): Institute of Geol-

.. notabilis nomurai (Otuka, 1943).

ogy and Paleontology, Tohoku University,
Japan, reg. no. 78684.

notabilis nomurai Otuka, 1943; 56, pl.
3(2), fig.10 [Serripes]. Nakanango, Saunai-
mura, Hiraga District, Akita Prefecture,
Honshu; Kurosawa Formation, Middie and
Upper Miocene. Depository (holotype): Geo-
logical Institute, University of Tokyo, Tokyo,
Japan, reg. no. ? Noda (1962) considers this
form identical with Serripes notabilis (Sow-
erby, 1915). However, the numerous Recent
and fossil specimens of the latter species are
distinguished by their more angulate outlines
and more truncated valves. The author there-

FIG. 10. Geographical and geological distribution of Yagudinella. 1—Recent; 2—Miocene; 3—Pliocene.

322 KAFANOV

fore finds it quite possible that this form
should retain its rank of a separate sub-
species.

notabilis Sowerby, 1915: 169, pl. 10, fig. 9
[Cardium (Serripes)]. Wakasa Bay, Honshu;
Recent. Depository (holotype): British Mu-
seum (Natural History), London, Great Britain,
reg. no. 1919.12.31.38. Recent distribution:
see Fig. 10. Fossil records reviewed by Noda
(1962).

yokoyamai Otuka, 1935: 603, pl. 2, fig. 3, 4
(holotype), 5, 6 [Serripes]. Ogino, Yamanogo-
mura, Yama District, Fukushima Prefecture,
Honshu; Hitosao Formation, Middle and Up-
per Miocene. Depository (holotype): Geo-
logical Institute, University of Tokyo, Tokyo,
Japan, reg. no. 2531.

ACKNOWLEDGEMENTS

| ат grateful to the following people for
providing information or helpful criticism of the
manuscript: Dr. Warren O. Addicott (U.S.
Geological Survey, Menlo Park, California,
U.S.A.), Miss Aileen Blake (British Museum
(Natural History), London, Great Britain), Prof.
Kenneth J. Boss (Museum of Comparative
Zoology, Harvard University, Cambridge,
Massachusetts, U.S.A.), Prof. Edouard
Fischer-Piette (Museum National d'Histoire
Naturelle, Paris, France), Dr. Yurij В.
Gladenkov (Geological Institute of the
U.S.S.R. Academy of Sciences, Moscow,
U.S.S.R.), Prof. Kotora Hatai (Saito Ho-on Kai
Museum, Sendai, Japan), Prof. A. Myra Keen
(Stanford University, Stanford, California,
U.S.A.), Dr. Rudolf Kilias (Museum Юг
Naturkunde, Humboldt-Universitat, Berlin,
D.D.R.), Dr. Frank H. Kilmer (Humboldt State
University, Arcata, California, U.S.A.), Prof.
Ilya М. Likharev (Zoological Institute of the
U.S.S.R. Academy of Sciences, Leningrad,
U.S.S.R.), Prof. Hiroshi Noda (Institute of
Geoscience, University of Tsukuba, Ibaraki,
Japan), Dr. С. Нфрпег Petersen (Universi-
tetets Zoologiske Museum, Kobenhavn,
Denmark), Dr. Sergej V. Popov (Paleonto-
logical Institute of the U.S.S.R. Academy of
Sciences, Moscow, U.S.S.R.), Dr. Joseph
Rosewater (National Museum of Natural His-
tory, Washington, D.C., U.S.A.), Dr. Victor O.
Savitskij (Central Laboratory of the Sakhalin
territorial geological board, Yuzhno-Sakhal-
insk, U.S.S.R.), Dr. Orest A. Scarlato and
Prof. Yaroslav |. Starobogatov (Zoological
Institute of the U.S.S.R. Academy of Sci-
ences, Leningrad, U.S.S.R.).

| thank Dr. Carol C. Jones for her coopera-
tion in modifying and editing this manuscript. |
thank also Mrs. Irina A. Barsegova (Institute
of Marine Biology, Far East Science Center of
the U.S.S.R. Academy of Sciences, Vladi-
vostok, U.S.S.R.) for translating this text into
English, Mrs. Olga V. Zvyagintseva and Mr.
Vladimir S. Makarov for drawing and Mrs.
Tatjana V. Kafanova for her cooperation in
compiling the bibliography.

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ZHIZHCHENKO, В. P., KOROBKOV, |. A,
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Абстракт

Система и состав подсемейства Clinocurdiinae Kafanov,

1975 (Bivalvia, Cardiidue)

AnexcaHmp И. Кабанов

Лаборатория хорологий, Институт биологии моря Лальневосточного

научного центра АН СССР, Владивосток, 690022, СССР

При ревизии кайнозойских Cardioidea автор установил новое

подсемейство Clinocardiinue. В дапной работе обсуждается история

изучения клинокардиин, объем и состав подсемейства и его положе-

ние в системе Carddiidue. Даны определительные таблицы для триб,

328 KAFANOV

родов, видов и подвидов, а также детальные диагнозы для подсе-
мейства, триб, родов и подродов. Поилагаемый каталог содержит

все описанные до сих пор таксоны вилового ранга со ссылками на
оригинальные описания, указаниями Ha типовые местонахозления M
места лепониоования типового материала. 3 необходимых случаях
даны таксономические замечания. ДЛЯ Curdium pauperculum Yokoy.ma,
1923 non ileek, 1871 предложено новое название: Serripes nodei

nom.nOoV,

MALACOLOGIA, 1980, 19(2): 329-334

DRILLING PREDATION OF BIVALVES IN GUAM:
SOME PALEOECOLOGICAL IMPLICATIONS!

Geerat J. Vermeij

Department of Zoology, University of Maryland, College Park, Md. 20742, US.A

ABSTRACT

All drill-holes in the valves of soft-bottom clams from Guam (Mariana Islands) are attributable
to naticid gastropods; hard-bottom bivalves are drilled exclusively by muricaceans. Edge-drilling,
which is reported in a naticid (Polinices tumidus) for the first time, is likely to have been a
common cause of death of tropical bivalves for much of Tertiary time. Drilling frequencies are
high in the Lucinidae and low in the Veneridae, Cardiidae, and Tellinidae. There is no straight-
forward relationship between bivalve shell traits and susceptibility to drilling. Underestimation of
drilling intensity is likely in studies of fossils, since naticids kill many bivalves before drilling is
initiated. Great variation in drilling frequencies at small and large geographical scales compli-
cates the search for temporal patterns in predation.

INTRODUCTION

Drilling is one of the few modes of predation
on mollusks that can be recognized postmor-
tem on shells and treated quantitatively.
There is a fairly extensive literature on the
methods employed by muricacean and
naticacean gastropods to detect and drill their
prey (for reviews see Carriker & Yochelson,
1968; Sohl, 1969; Vermeij, 1978). The impact
of drilling gastropods on populations of Re-
cent bivalves is known primarily for temper-
ate hard-bottom bivalves (Chapman, 1955;
Seed, 1969; Fotheringham, 1974; Bayne &
Scullard, 1978; Menge, 1978a, b; Suchaneck,
1978); comparatively few estimates of drilling
intensity have been made for soft-bottom bi-
valves (Ansell, 1960; Reyment, 1967; Green,
1968; Jackson, 1972; Schafer, 1972), and lit-
tle is known about drilling in the tropics. Para-
doxically, drilling on fossil bivalves has been
relatively well studied; data on the frequency
of drilled valves are available for the Eocene
(Fischer, 1966; Taylor, 1970; Adegoke &
Tevesz, 1974), Miocene (Hoffman et al.,
1974; Kojumdjieva, 1974; Watkins, 1974;
Dudley & Dudley, 1980), Pliocene (Boek-
schoten, 1967; Robba & Ostinelli, 1975), and
Pleistocene (Stump, 1975). Several of these
studies deal with warm-water bivalves.

In order to extend our knowledge of spatial
and temporal variations in drilling predation,
more data are needed on drilling of Recent
bivalves, especially in the tropics. Information

of this type will also be of practical value in
culturing edible clams. In this paper | report
drilling frequencies of the common bivalves
on the reef-flats of Guam, the southernmost of
the Mariana Islands in the tropical western
Pacific; and | describe for the first time the
occurrence of edge-drilling by naticid gastro-
pods.

MATERIALS AND METHODS

Field estimates of drilling predation were
obtained from large samples of empty valves
from several reef-flats on Guam. Valves were
collected by hand or with the aid of a hand-
held dredge with 6 mm mesh in the period of
January to May, 1979. All valves were sorted,
identified, inspected for the presence of drill-
holes, and measured with calipers to the
nearest millimeter. Chi-square tests reveal
that the number of right valves was never sig-
nificantly different from the number of left
valves in any of the samples listed in Table 1.
Consequently, there is no evidence for differ-
ential sorting of right and left valves such as
that documented in the Netherlands for
Donax vittatus (da Costa) by Lever & Thijssen
(1968). No more than one drill-hole was ob-
served on any valve; therefore, in the case of
holes drilled away from the valve margin,
each drilled valve represents one drilled indi-
vidual (two valves), and the intensity of drilling
is expressed as twice the number of drilled
valves divided by the total number of valves.

Contribution number 131 from the University of Guam Marine Laboratory.

(329)

330 GEERAT J. VERMEIJ

Holes which are drilled at the valve margin
usually affect both valves, though not neces-
sarily to the same extent; marginal drills in a
right and left valve of similar size are regarded
as representing a single penetration only if the
position of the hole in the two valves is the
same. In all other cases, it is assumed that a
valve which is drilled at the margin represents
one drilled individual, so that the frequency of
edge-drilling is twice the number of edge-
drilled valves divided by the total number of
valves in the sample.

In order to determine how bivalves are
killed by naticids, seven Polinices tumidus
(Swainson) (25.7 mm to 35.4 mm long) and
one Natica gualteriana Récluz (20.8 mm in
diameter) were maintained individually in run-
ning sea water with various prey species at
the University of Guam Marine Laboratory. In
addition, four N. gualteriana from Thursday
Island (Torres Straits, Queensland) were kept
in running sea water on board the R.V. Alpha
Helix. The sediment on the bottom of the
aquaria in which the snails were kept was a
muddy sand 14 mm to 35 mm deep.

RESULTS AND DISCUSSION

Muricacean gastropods are responsible for
all drill- holes observed on the valves of hard-
bottom clams (Mytilidae and Arcidae) in
Guam. At Gun Beach, on the west coast of
the island, Chicoreus brunneus (Link) ap-
pears to be the principal predator of the semi-
infaunal bench mussel Modiolus auriculatus
(Krauss) (15 observations). At Pago Bay, on
the windward east coast, where C. brunneus is
absent, M. auriculatus is preyed upon by spe-
cies of Morula. Arca avellana Lamarck, which
in Guam is usually confined to crevices and
the under surfaces of stones, is rarely drilled.

All drill-holes in the valves of soft-bottom
clams (Lucinidae, Cardiidae, Veneridae, and
Tellinidae) are attributable to naticid gastro-
pods. Muricaceans, which commonly attack
soft-bottom bivalves elsewhere in the tropics
and subtropics (Wells, 1958; Paine, 1963;
Vermeij, 1978) are absent from shallow-water
sands and muds in Guam. Two types of drill-
hole are present in the soft-bottom bivalves
examined. The first is the typical circular
naticid hole with tapering walls (Carriker &
Yochelson, 1968), which penetrates through
one of the two valves. The second type is a
hole drilled at the commissure between the
two valves. The hole is a beveled cone like
that of the first type, but it is expressed on a

valve as a semicircular nick in the margin.
Edge-drills of this type can occur anywhere
along the commissure.

Laboratory observations of the two com-
mon reef-flat naticids in Guam show that
edge-drilling is commonly practiced by
Polinices (Polinices) tumidus but never by
Natica (Naticarius) gualteriana (Table 2). Of
49 clams eaten by P. tumidus in the labora-
tory, 30 (61%) were drilled at the margin, 4
(8.2%) were drilled through one valve, and 15
(31%) were killed without injury to the shell. Of
19 bivalves drilled by N. gualteriana, 17 (89%)
were drilled through one valve, and 2 (11%),
both Arcopagia robusta) were eaten without
injury to the shell.

То my knowledge, edge-drilling has not
previously been reported for naticid gastro-
pods, even though it is widespread among
Muricacea such as Thais, Muricanthus, and
Ceratostoma (Chapman, 1955; Wells, 1958;
Vermeij, 1978). Careful studies show that
Polinices (Neverita) duplicatus Say, P.
(Euspira) catena (da Costa), P. (E.) nitida
(Donovan), and Natica (Natica) millepunctata
Lamarck drill in the vicinity of the umbo or in
other central regions of the valve, but not at
the shell margin (Bôttger, 1930; Carriker,
1951; Ziegelmeier, 1954; Paine, 1963;
Negus, 1975; Edwards & Huebner, 1977).
Many taxa in the Naticidae, including such
widely distributed groups as Polinices
(Mammilla), P. (Glossaulax), P. (Stigmaulax),
P. (Hypterita), Sinum, and Eunaticina, have
not yet been studied with respect to drilling
behavior. Polinices (Polinices), the only sub-
genus in which edge-drilling is known thus far
in the Naticidae, is nearly circumtropical in
distribution and has a long history beginning
in the Paleocene (Marincovich, 1977); P. (P.)
tumidus has a broad geographical range ex-
tending from Hawaii to East Africa (Kilburn,
1976). Edge-drilling by naticids may have
been important to bivalves throughout the
tropics for most of Tertiary time.

Table 1 presents frequencies of drilling in
the 12 bivalve species for which sample sizes
were judged to be sufficient (20 valves or
more). Among soft-bottom bivalves, the only
species with consistently high frequencies of
drilling are the lucinids Codakia bella and
Wallucina sp. Members of the Veneridae and
Tellinidae have significantly lower drilling fre-
quencies than do the Lucinidae (p < 0.001 in
each case, Mann-Whitney U-Test), but there
is no significant difference between the Ven-
eridae and Tellinidae. The cardiid Fragum

DRILLING PREDATION 331

TABLE 1. Frequencies of edge-drilling (FE) and of total drilling (For) in bivalves from Guam.

Mean size Mean size
all valves drilled valves
Species Site N РЕ For + SD (mm) + SD (mm)
Arcidae
Arca avellana Lamarck PB 51 0 0 И ЗЕЕ —
Mytilidae
Modiolus auriculatus Krauss SH 44 .091 .091 PV L GLS 22.5
GB 140 .057 27 20:7 = 6:8 21.9 = 63
РВ 31 0 .58 ИДЕЕ 32.4 + 2.9
Lucinidae
Codakia bella (Conrad) PR 59 0 ATA 17821374 20/3242
CL 48 UTE 33 16.8 + 4.5 15.3. == 2.6
BI 117 ¿5% 37 WAG StS 17.8 = 38
РС 48 .21 .46 ВЕ 257; 1210216
TB 64 1939 575 — —
Wallucina sp. AC 51 .20 .31 13:3 318 (20215
PG 504 24 43 HOME ra = lan
ТВ 110 33 55 = —
Veneridae
Gafrarium pectinatum (L.) PR 25 0 0 РЗ: ЕЕ —
РВ 21 .048 .048 23.9+ 4.8 31
BI 68 .088 12 251857, 35472
AC 26 0 15 22.6 + 8.0 16.5
CL 21 19 19 23.7 + 4.6 1725
G. tumidum Röding SB 32 0 0 ISS —
Periglypta reticulata (L.) PB 22 .091 .091 178 = 68 20
Timoclea marica (L.) CL 41 0 .049 17272-20378 17
Cardiidae
Fragum fragum (L.) TB 76 0 0 25.9 + 6.4 —
BI 35 0 0 262 83 =
PC 54 0 0 ЕЕ ИВ —
АС 79 1023 023 1S2EEN5 A 23
CL 39 .026 226 WES 2= 70 10
Tellinidae
Arcopagia robusta (Hanley) PC 318 0 .013 — —
AC 93 022 .022 1219 =" 210 13
CL 40 025 .025 148+ 24 12
TB 152 013 .026 1225) == 9 =
Quidnipagus palatam lredale PR 57 0 .035 43.1 + 6.4 45
AC 213 019 056 S2 ME 16:3 26.1 + 9.0
PC 27 0 074 327 = 74 12
BI 86 070 12 SOSIEGO 34.0 + 9.0
PB 45 089 .18 SUSE 2 38.9 + 6.9
Scissulina sp. AC 42 0 .048 ees a 14
TB 76 .053 .079 — =
PC 91 .022 ail 14.2 = 1:9 13 SE 2210
CL 22 .18 27 LOTES 27.0 + 6.6
Key: Sites:
N Number of valves AC Alupang Cove, west coast, north of Agana Bay
FE Frequency of edge drilling BI Bangi Island, Agat, west coast
Fpr Frequency of total drilling CL Cocos Lagoon, southwest part, south end of Guam

GB Gun Beach, west coast, north of Tumon Bay

PB Pago Bay, east coast, at University of Guam Marine Laboratory
PC Piti Channel, near Apra Harbor, west coast

PR Pago River, east coast

SB Sasa Вау, part of Apra Harbor, west coast

SH Shark's Hole, west coast

TB Tumon Bay, west coast

332 СЕЕВАТ J. VERMEIJ

TABLE 2. Bivalves eaten by Polinices tumidus (п

7) in the laboratory.

Number of individuals killed by means of

Prey species Conventional drilling Edge-drilling Questionable means
Codakia bella 2 6 0
Gafrarium pectinatum 0 74 1
Timoclea marica 0 0 4
Arcopagia robusta 0 15 4
Quidnipagus palatam 2 2 6
Total 4 30 15

fragum is rarely drilled. The taxonomic dis-
tribution of edge-drilling is similar to that of
total drilling frequency.

Within the size range of shells in the sam-
ples, drilled valves are not significantly differ-
ent in size from undrilled valves in any sample
(Table 1). (p > 0.10 in all cases, T-Test). In
general, right valves are as likely to be drilled
as left valves; however, there is a significant
tendency for left valves to be drilled more
often than right valves in Codakia bella from
Bangi Island, Wallucina sp. from Piti Channel,
and Modiolus auriculatus from Gun Beach
(p < 0.05, chi-square test).

There is no straightforward relationship be-
tween shell traits and susceptibility to drilling
in the bivalves from Guam. Previous authors
have pointed to strong external sculpture,
thick shells, and tight valve closure as traits
that should prevent or prolong drilling (Rey-
ment, 1967; Taylor, 1970; Vermeij & Veil,
1978). Robba & Ostinelli (1975), however,
found that strongly sculptured bivalves from
the Pliocene of Italy had higher frequencies of
drilling (mean 0.17) than did smooth or weakly
ornamented species (mean 0.055). Hoffman
et al. (1974) found no correlation between
sculpture and drilling intensity in bivalves from
the Upper Miocene of Poland. In the Guam
bivalves, low frequencies of drilling are char-
acteristic of two contrasting groups of species:
(1) those with tight valve closure (crenulated
valve margins, well-developed heterodont
hinge), thick shells, and strong sculpture
(Cardiidae and Veneridae); and (2) species
with relatively weak valve closure (smooth
shell margins and less interlocking hinge),
weak sculpture, and thin shells (Tellinidae).

Several factors may contribute to the lack of
correspondence between shell characters
and drilling frequency. Some bivalves (notably
the jumping cockle Fragum fragum) can
probably escape from naticid predators in the
same way that they escape from other rela-

tively slow predatory gastropods and aster-
oids (see Ansell, 1969; Nielsen, 1975; and
Vermeij, 1978 for review and examples). Four
Fragum kept for two weeks with N. gual-
teriana in the laboratory were not eaten. The
impact of naticid predation may be seriously
underestimated in species such as Arcopagia
robusta and Quidnipagus palatam which can
be eaten by naticids without drilling. It is likely
that these clams suffocate while being en-
veloped by the predator's foot before drilling
has proceeded very far. In this connection it is
interesting that lucinids, which are generally
tolerant of anaerobic conditions and can re-
main tightly closed for long periods (Jackson,
1973), were always drilled when eaten by
naticids in the laboratory (11 observations).

Underestimation of predation by naticids
may be a common problem in studies of fos-
sils. Turner (1955), for example, noted that
Polinices duplicatus occasionally consumes
razor clams (Ensis directus Conrad) by at-
tacking the soft parts through the gaping
posterior end of the shell, and that Ensis is
never drilled in nature. Edwards (1969)
showed that the gastropod Olivella biplicata
Sowerby is often suffocated in the foot of
Polinices before drilling has ensued. Reliable
comparative data on drilling intensity should
therefore be obtained from taxa whose mod-
ern representatives are known to be tolerant
of prolonged valve or opercular closure.

It is also important to point out that drilling
may be overestimated from studies based on
intact empty valves. Many crustaceans and
fishes are known to consume bivalves by
crushing the shell (for a review see Vermeij,
1978). Although it is difficult to estimate the
importance of this cause of death, thin-shelled
tellinids in tropical waters appear to be es-
pecially vulnerable to predation by fishes,
whereas deeper-burrowing and thicker-
shelled lucinids are less susceptible. Among
mollusk-eating fishes of the West Indies, for

DRILLING PREDATION 333

example, 13 species ingest tellinids, 9 eat
venerids, and only 5 consume lucinids (com-
pilation from Warmke & Erdman, 1963;
Randall, 1967; Randall & Warmke, 1967). Es-
timates of drilling intensity in fossils are thus
most reliable for thicker-shelled species that
live deeply buried in the sediment.

With the various sources of error firmly in
mind, it is instructive to inquire how the drilling
frequencies of bivalves in Guam accord with
evidence for geographical and temporal vari-
ation in drilling intensity. The current con-
sensus of opinion is that drilling gastropods
first appeared during the Albian epoch of the
Cretaceous period (Fischer, 1962; Carriker &
Yochelson, 1968; Sohl, 1969). Present-day
intensities of drilling were reached no later
than the Eocene for turritellid gastropods
(Dudley & Vermeij, 1978) and Early Miocene
for glycymerid bivalves (Thomas, 1976).
There is evidence from turritellids that the in-
tensity of drilling is up to three times higher in
Recent tropical and subtropical species than
in cold-temperate forms (Dudley & Vermeij,
1978). Lucinids from Guam (median fre-
quency 0.40, 8 samples) are significantly
more prone to drilling than were warm-tem-
perate lucinids from Upper Miocene deposits
in Poland (median drilling frequency 0.21 for 4
samples of greater than 20 valves each; data
from Hoffman et al., 1974). However, a sam-
ple of Divaricella spp. from the Upper Mio-
cene of warm-temperate Bulgaria (frequency
0.75; Kojumdjieva, 1975) shows the same

_high intensity of drilling as the most perforated
lucinid sample from Guam. No significant dif-
ferences in drilling frequency exist between
the venerids of Guam (median frequency
0.065, 8 samples) and those of tropical
Eocene Europe and Nigeria (median fre-
quency 0.11, 7 samples) or warm-temperate
Late Miocene Poland and Bulgaria (median
frequency 0.20, 13 samples; p > 0.10 in all
cases by Mann-Whitney U-test) (fossil data
from Fischer, 1966; Taylor, 1970; Adegoke &
Tevesz, 1974; Hoffman et al., 1974; Kojum-
djieva, 1974). With the geographical coverage
of both Recent and fossil samples as patchy
as it is, however, it would be rash to conclude
from these comparisons that the intensity of
drilling in Recent Indo-West-Pacific bivalves
has remained unchanged since Eocene time.
Data on bivalves from Panama and Venezu-
ela (Vermeij, unpublished), in fact, reveal
much higher frequencies of drilling in venerids
than were observed in Guam.

From this comparison and from the data in
Table 1, it is evident that the intensity of drill-

ing varies greatly from place to place, on botha
local and a larger geographical scale. For ex-
ample, Codakia bella from Tumon Bay suffers
more than 4 times as much drilling predation
as does the same species in Pago Bay. Varia-
tion in predation intensity is likely to be the
rule rather than the exception (see also
Kojumdjieva, 1974; Dudley & Vermeij, 1978;
Menge, 1978a, b), and must be taken into ac-
count in the search for geographical and tem-
poral patterns of predation.

ACKNOWLEDGMENTS

| am grateful to Edith Zipser, the students
and staff of the University of Guam Marine
Laboratory, and the scientists and crew of the
R. V. Alpha Helix for their help in the field and
laboratory. This work has been supported by
grants from the Program of Biological Ocean-
ography, National Science Foundation.

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INDEX TO SCIENTIFIC NAMES IN VOLUME 19, NOS. 1-2
An asterisk (*) denotes a new taxon

Abra Agmata, 271
aequalis, 224 Agriolimax, 143
lioica, 223 ainuanum, Cardium, 311, 312
Acanthocardia, 298 ainuanum, Ciliatocardium, 311
snatolense 311, 313 album, Serripes, 318
snatolensis, 313 albus, Nassarius, 224
Acanthochitonida, 253 alta, Basilissa, 33, 50, 52, 53, 55
Acanthochitonina, 253 alternata, Tellina, 224
Acardo, 316 alternatum, Bittium, 246
acicularis, Cypraea, 290 alternatus, Eutrochus, 28
Acirsa Alvania, 225
borealis, 245 areolata, 221, 246
Acmaea brychia, 245
testudinalis, 239, 245 amabilis, Margarita, 40, 42
virginea, 238 amabilis, Solariella, 1, 36, 37, 40, 42
Acochlidioidea, 261 Amauropsis
Acteocina islandica, 245
canaliculata, 222 amazonica, Calliostoma, 31
Acteon, 260 americana, Astraea, 291
Actinocerida, 271 Amicula
actinophora, Calliotropis, 15, 53-55 vestita, 233
actinophora, Margarita, 14 Ammonitida, 271
actinophora, Solaricida, 12, 14 Ammonoida, 254, 258, 265, 271, 273, 278
aculeata, Crepidula, 224 Amphigastropoda, 254
aculeus, Cingula, 245 Amphineura, 268
Aculifera, 268, 269 Ampullotrochus, 25
acuta, Nuculana, 223, 248 amygdales, Yoldia, 246
acutilira, Sinuitopsis, 253 Anachis
acutus, Nassarius, 223 avara, 215, 216, 222, 248
adelae, Calliostoma, 55 Anadara, 77-80, 84
Adenopoda, 249, 257, 266-270, 272, 278 anomala, 194
Admete cuneata, 194
couthouyi, 245 ovalis, 216, 223, 248
aeglees, Calliotropis, 8, 9, 11, 13, 14, 20, 40, 53 transversa, 216, 223, 248
aeglees, Niso, 224 Anadariinae, 79
aeglees, Solaricida, 8 Anaspidea, 261, 270
aeglees, Trochus, 7 anatina, Anodonta, 189, 190
aegleis, Calliotropis, 55 anceps, Desmarestia, 110
aegleis, Machaeroplax, 3 anceps, Helisoma, 97
aegleis, Margarita, 9, 13, 20, 40 Ancistrobasis, 51
aegleis, Solaricida, 9 costulata, 35, 51, 52
aegleis, Solariella, 7, 11, 13, 20 depressa, 51, 52
aeola, Bathybembix, 55 rhyssa, 51
Aeolidiina, 262 Ancylidae, 96, 103
aequalis, Abra, 224 Ancylus, 103, 104, 107, 269
Aequipecten fluviatilis, 103, 106
glyptus, 223, 248 andoi, Clinocardium, 308
MUSCOSUS, 224 andoi, Keenocardium, 308
phrygium, 223, 248 angulata, Papyridea, 315
aequistriata, Tellina, 224 angulata, Profulvia, 315
affinis, Machaeroplax, 37 angulata, Turbinella, 291, 292
affinis, Solariella, 36 angulifera, Littorina, 291, 292
Afossochitonida, 253 Angustiradulata, 265, 266
Afossochitonidae, 253 annae, Cardium, 303
agalma, Astele, 27 Anodonta anatina, 189, 190
agalma, Calliostoma, 27 anomala, Anadara, 194
agilis, Tellina, 222, 236 Anomalodesmata, 263, 264, 270

(335)

336 MALACOLOGIA

Anomia

simplex, 223

squamula, 221, 234, 239, 247
anoxia, Echinogurges, 53, 55
anoxia, Solariella, 21
anoxius, Echinogurges, 20, 22

antarctica, Laevilacunaria, 110, 111, 116-119,

123 125127

antarctica, Margarella, 110, 111, 113, 114, 123,

124

Anthobranchia, 270, 273, 278
Antillachelus

dentiferum, 35

dentiferus, 35

vaughani, 35
Aphrodita, 316
Aphrodite, 316

columba, 318

groenlandicum, 318
apicinum, Calliostoma, 26
“Aplacophora,” 249, 251, 252, 268, 272
Aplotegmentaria, 252, 270
Aplysia

willcoxi, 222
Aplysiomorpha, 261
apoda, Gigartina, 110
Aporrhais

occidentalis, 245
arakawae, Clinocardium, 308
arakawae, Keenocardium, 308
arakawaense, Cardium, 319
Arca, 78, 79

avellana, 330, 331
Arcacea, 79, 84
Archaeoconcha, 257, 267
Archaeogastropoda, 4, 111, 261, 270, 273, 278
Archaeopulmonata, 261, 262, 270
Archinacellina, 255
Architectonicidae, 32
Arcidae, 77-85, 330, 331
Arcopagia

robusta, 330-332
arenaria, Mya, 188, 221, 234, 238, 247
arenosa, Lyonsia, 246
arenosa, Pandora, 224
areolata, Alvania, 221, 246
Arcina, 264
Arcinae, 77, 79
Arcoida, 77-85
Arcopsis, 84
arctatum, Mesodesma, 221, 237, 238, 247
Arctica, 239

islandica, 213, 215, 221, 234, 236, 239, 247
arctica, Hiatella, 225
arctica, Panomya, 246
arctica, Portlandia, 238
arcticum, Cardium, 312
arcticum, Ciliatocardium, 312
arenicoloides, Vasticardium, 303
Argopecten

gibbus, 223, 248

irradians, 237
Arion, 143, 144

Arminina, 262
asagaiense, Cardium, 311, 312
asagaiense, Cerastoderma, 311-313
asagaiense, Ciliatocardium, 311-313
Ascocerida, 271
Ascoglossa, 261, 270
Ascophyllum, 240
Ascoseira, 116, 118
mirabilis, 110
Ashmunella, 143, 144
asperrima, Astele, 34
asperrima, Calliostoma, 34, 35
asperrima, Dentistyla, 34, 35, 53, 55
asperrima, Margarita, 34
asperrima, Solariella, 34
asperrimum, Dentistyla, 34-36
Astarte, 225
borealis, 246
castanea, 214, 221, 247
crenata, 213, 215, 225
elliptica, 246
montagui, 246
subaequilatera, 213, 225
undata, 216, 221, 225, 237, 238, 247
Astele, 32
agalma, 27
asperrima, 34
tejedori, 32
Astraea
americana, 291
phoebia, 291
tecta, 291
atacellana, Nucula, 247
atlantica, Xylophaga, 221, 247
Atlantidae, 63-76
atlantis, Calliostoma, 31, 54
atlantis, Kombologion, 31
atomus, Omalogyra, 246
Atrina
rigida, 224
Aulacocerida, 265, 271
aurantia, Partula, 131
auriculatus, Modiolus, 330-332
auritula, Pisania, 291
Austrovenus, 190, 193-195
stutchburyi, 157-199
Autobranchia, 264, 270
Autolamellibranchia, 264
avara, Anachis, 215, 216, 222, 248
avellana, Arca, 330, 331
avena, Hyalina, 290
baboquivariensis, Sonorella, 201-206
Bactritida, 271
Bactritites, 265
bairdi, Bathymophila, 5, 6
bairdi, Calliostoma, 29
bairdi, Margarites, 5-7, 54, 55
bairdi, Umbonium, 5, 7
bairdii, Calliostoma, 29, 222
bairdii, Kombologion, 29
bairdii, Margarites, 54
balthica, Macoma, 225, 234, 236, 238, 247
banyulensis, Nematomenia, 252

INDEX, VOL. 19 337

Barbatia, 77-79, 82-84
novaezelandiae, 83
barbouri, Calliostoma, 33, 34, 53, 55
Barnea
truncata, 223
Basilissa, 32, 33, 49-51, 53
alla 33, 50, 52, 53,55
cinctellum, 33
costulata, 35, 51-53, 55
delicatula, 50
depressa, 51, 52
discula, 50-53, 55
oxytoma, 50
rhyssa, 5,535.55
superba, 49, 50
Basommatophora, 261, 270
Bathybembix, 2
aeola, 55
Bathymophila, 5
bairdi, 5, 6
euspira, 5-7
euspirus, 5
nitens, 5
Belemnites, 265
Belemnitida, 271
bella, Codakia, 330-333
bellastriata, Semele, 224
Belleromorpha, 254, 258, 273, 278
Bellerophontacea, 254
Bellerophontida, 253-255, 267, 270, 273, 278
Bellerophontina, 255

bennetti, Laevilacunaria, 110, 111, 117, 118, 128,

125 126

bennetti, Pellilacunella, 110, 117, 118
bicarinata, Oenopota, 221, 245
bidentata, Cyclichnella, 224, 248
bigelowi, Calliostoma, 32, 54
Biomphalaria, 104

glabrata, 103

pfeifferi, 96
biplicata, Olivella, 332
Bithynia, 88
Bittium

alternatum, 246

Bivalvia, 248, 257, 258, 261, 265, 267-270, 273,

278, 297
blandum, Cardium, 308
blandum, Keenocardium, 308
boreale, Cardium, 308, 318
boreale, Keenocardium, 308
boreale, Serripes, 318
borealis, Acirsa, 245
borealis, Astarte, 246
borealis, Cyclocardia, 214, 216, 221, 234, 237, 247
borealis, Marginella, 222
borealis, Solemya, 247
borealis, Trichotropis, 245
Boreotrophon,

clathratus, 245

braunsi, Cardium, 305, 306
braunsi, Clinocardium, 306, 307
braunsi, Fuscocardium, 306, 307
brevis, Lolliguncula, 279-288
brooksi, Cardium, 308

brooksi, Cerastoderma, 308
brooksi, Ciliatocardium, 312
brooksi, Papyridea, 312
brunnea, Calliostoma, 32
brunnea, Fluxina, 32
brunneum, Calliostoma, 32, 34, 51, 53, 55
brunneus, Chicoreus, 330
brychia, Alvania, 245
Bucardium, 298
Buccinulidae, 121
Buccinum

glaciale, 245

hancocki, 238

plectrum, 238, 245

scalariforme, 245

terrae-novae, 238

undatum, 213, 215, 216, 221, 234, 236, 247
buelowi, Cardium, 308, 309
buelowi, Keenocardium, 308
Bulinus

contortus, 147

depressus, 154

globosus, 147

jousseaumei, 154

tropicus, 154

truncatus, 147, 153
Bullia, 293
Bullomorpha, 261
burnsii, Chione, 184
Busycon, 293

canaliculatum, 216, 222, 248

carica, 216, 222, 248

contrarium, 222, 290, 294
Bythinia, 74
Cadulus

carolinensis, 222
caeca, Lepeta, 245
Caecum, 254
Caenogastropoda, 261, 270
calatha, Calliotropis, 9-13, 20, 53, 55
calatha, Solariella, 11, 40
calatha, Solaricida, 9, 10, 12
calcarea, Macoma, 246
californianum, Cardium, 305
californianum, Clinocardium, 305
californiense, Cardium, 299, 300, 307, 309
californiense, Clinocardium, 307, 310
californiense, Keenocardium, 307-310
californiensis, Chione, 187
caliginosa, Laevilitorina, 123
caliginosa, Littorina, 123
Calliostoma, 1-4, 15, 25, 26, 28, 31-34, 51

adelae, 55

agalma, 27

amazonica, 31

apicinum, 26

asperrima, 34, 35

atlantis, 31, 54

bairdi, 29

bairdii, 29, 222

barbouri, 33, 34, 53, 55

bigelowi, 32, 54

brunnea, 32

brunneum, 32, 34, 51, 53, 55

338 MALACOLOGIA

cinctellum, 32, 33, 54 Cardiidae, 297-299, 302, 329
circumcinctum, 33, 54 Cardiinae, 299

corbis, 17, 18, 35 Cardioidea, 297

cubanum, 31, 54 Cardita

dentifera, 34

dentiferum, 35

echinatum 27, 28 33153155
euglyptum, 55

fascinans, 55

hassler, 34

hendersoni, 30, 54, 55
imperialis, 15

javanicum, 34, 55

jeanneae, 31

jujubinum, 1, 28, 29, 34, 53, 55

marionae, 55
occidentale, 26, 246
orion, 54, 55
perspectivum, 28
psyche, 29, 30, 53-55
pulcher, 26

pulchrum, 1, 26, 27, 31, 53, 55

rawsoni, 28

roseolum, 26-28, 54, 55
sapidum, 30, 53, 55
sarcodum, 55
sayanum, 31, 32, 53, 55
schroederi, 30, 31, 53, 55
sericifila, 34

springeri, 32
subumbilicatum, 29
suturale, 26
tampaensis, 32

granulata, 233, 234

Cardium, 298, 301, 308, 320

ainuanum, 311, 312

annae, 303

arakawaense, 319

arcticum, 312

asagaiense, 311, 312
blandum, 308

boreale, 308, 318

braunsi, 305, 306

brooksi, 308

buelowi, 308, 309
californianum, 305
californiense, 299, 300, 307, 309
ciliatum, 299, 300, 308, 310-313
comoxense, 312

coosense, 303, 308, 309
corbis, 299, 305

dawsoni, 310, 312
decoratum, 299, 305
edentula, 318

fabricii, 317, 318

fastosum, 308, 309

fucanum, 308, 309

gallicum, 303

groenlandicum, 316, 318, 320
groenlandicus, 317, 318
hamiltonense, 315
hanpeizanense, 303

tejedori, 32 hanzawai, 303
tiara, 18, 45 hayesii, 312
torrei, 31, 54 hizenense, 303
veliei, 26 hudsoniense, 304

yucatecanum, 27, 29, 53, 55
Calliostomatinae, 4, 25, 50

Calliotropis, 2, 4, 6, 7, 20, 23, 24, 37, 46

actinophora, 12, 14, 15, 53-55

aeglees, 8, 9, 11, 13, 14, 20, 40, 53

aegleis, 55

calatha, 9-13, 20, 53, 55

infundibulum, 15

lata, 9, 11

lissocona, 8, 14, 53, 55

ottoi, 6, 9

regalis, 7-9

rhina, 9, 12, 13, 20, 42, 54, 55

rotella, 45, 46

vaillanti, 8, 9

watsoni, 24, 25
campanulatum, Helisoma, 97
campechiensis, Mercenaria, 223
canaliculata, Acteocina, 222
canaliculata, Cylichnella, 248

canaliculatum, Busycon, 216, 222, 248

canaliculatus, Turbo, 291

cancellata, Chione, 157-199, 224

cancellata, Odostomia, 223
Cantharidus

coruscans, 121, 123
caprearum, Middendorffia, 252

icelandicum, 312
islandicum, 312
iwasiroense, 308
jobanicum, 303
kinsimarae, 303
laperousi, 319
matchgarense, 311, 313
meekianum, 305
mutuense, 311, 313
nanum, 305

notabile, 301, 320
notabilis, 322

nuttallii, 299, 300, 305, 306
ovata, 306, 307
pantecolpatum, 303
pauperculum, 297, 319, 320
pseudofastosum, 306
pubescens, 311, 312
puchlense, 303
rhomboideum, 303
scapoosense, 303
shinjiense, 311, 313
snatolense, 311, 313
snatolensis, 313
sookense, 303
squalidus, 320
taracaicum, 304

INDEX, VOL. 19

tokunagai, 306, 307

uchidai, 307

unciangulare, 320

uyemurai, 311, 313

vulva, 316

yakatagense, 310, 313

уатазаки, 311, 313
“Cardium groenlandicum,” 233
carica, Busycon, 216, 222, 248
Carinaria, 63-76

lamarcki, 63-76
Carinariidae, 63-76
carinata, Seguenzia, 50
carolinensis, Cadulus, 222
Cassis, 293

flammea, 291
castanea, Astarte, 214, 221, 247
catascopium, Lymnaea, 87-101
catena, Euspira, 330
catena, Polinices, 330

Caudofoveata, 106, 249-252, 257, 258, 261, 264,

266-270, 272, 278
Cavibelonia, 252, 270
Cepaea, 144
Cephalaspidea, 261, 270
Cephalopoda, 261, 265-269, 271, 278, 279
Cepolis, 143, 144
Cerastoderma, 297-299

asagaiense, 311-313

brooksi, 308, 312

ciliatum, 308

coosense, 309

etheringtoni, 303

esutoruense, 303

glaucum, 298

hanzawai, 303

hizenense, 303

iwasiroense, 309

matchgarense, 311, 313

pinnulatum, 221, 235, 238, 247

scapoosense, 303

uyemurai, 311, 313

yakatagense, 310, 313

yamasakii, 311, 313
Ceratostoma, 330
cerina, Kurtziella, 223, 248
cervus, Cypraea, 290
Chaetodermatida, 270
Chaetodermatina, 250
Chaetodermoidea, 250
Chaetodermomorpha, 250
Chamelea

gallina, 185, 189
championi, Epitonium, 223
Chelodida, 253, 265, 269, 270
Chicoreus

brunneus, 330
chikagawaense, Ciliatocardium, 311, 312
chikagawaense, Clinocardium, 311, 312
Chione, 190, 192-195

burnsii, 184

californiensis, 187

cancellata, 157-199, 224

chipolana, 193

fluctifraga, 187

grus, 191, 224

intapurpurea, 193, 224

latilirata, 224

mazyckii, 184

paphia, 157-199

pubera, 193, 194

succincta, 187

ulocyma, 184, 185

undatella, 157-199
Chioninae, 157-199
chipolana, Chione, 193
Chitonida, 253, 270
Chlamys

islandica, 234, 236, 238, 247
Ciliatocardium, 297, 300-302, 310, 311

ainuanum, 311, 312

arcticum, 312

asagaiense, 311-313

brooksi, 312

chikagawaense, 311, 312

ciliatum, 310-313

comoxense, 312

dawsoni, 310, 312

ermanensis, 311, 312

hataii, 310, 312

hayesii, 312

icelandicum, 312

iwatense, 311, 313

makiyamae, 311, 313

matchgarense, 311, 313

mutuense, 311

padimeicum, 313

pubescens, 311, 313

sachalinense, 313

salvationemense, 313

schmidti, 311, 313

shinjiense, 311, 313

snatolense, 311,313

snatolensis, 313

tigilense, 311, 313

uyemurai, 311, 313

yakatagense, 310, 313

yamasakii, 311, 313
ciliatum, Cardium, 299, 300, 308, 310-313
ciliatum, Cerastoderma, 308
ciliatum, Ciliatocardium, 310-313
ciliatum, Clinocardium, 237, 246, 312, 313
cinctellum, Basilissa, 33
cinctellum, Calliostoma, 32, 33, 54
cinctellum, Eutrochus, 32
cinctellum, Leiotrochus, 33
cinerea, Cypraea, 290
cinerea, Margarita, 114, 123
cinerea, Urosalpinx, 236

Cingula
aculeus, 245
Circinae, 193

circumcinctum, Calliostoma, 33, 54
Cittarium, 53
pica, 53, 55, 291
Cladophora, 87
clathrata, Distorsio, 224
clathratus, Boreotrophon, 245

339

340 MALACOLOGIA

clathratus, Trophon, 123 concentrica, Ervilia, 224

clausa, Natica, 221, 238, 245 Conchifera, 249, 250, 252, 254, 257, 259, 267-270,
Clavagelloidea, 269 272, 278

clavata, Margarita, 20 Conchostraca, 264

clavata, Solariella, 20 concinna, Nacella, 121, 123

clavatus, Echinogurges, 9, 20, 22, 53-55 concinna, Patinigera, 121, 123

clavatus, Trochus, 1, 20 Conocardiida, 264, 265, 271

Clinocardiinae, 297-299, 301-304 Conocardioidea, 264

Clinocardiini, 299, 301-303, 305 conradi, Thracia, 221, 235, 247

Clinocardium, 297-307 constricta, Micropiliscus, 41, 43, 45

andoi, 308 constricta, Solariella, 53, 55
arakawae, 308 contortus, Bulinus, 147, 153
asagaiense, 308 contortus, Planorbis, 97

braunsi, 306, 307 contracta, Corbula, 223
californiaum, 305 contrarium, Busycon, 222, 290, 294
californiense, 307, 310 conula, Trochus, 25
chikagawaense, 311, 312 conulus, Trochus, 25, 26

ciliatum, 237, 246, 312, 316 Conus, 293

corbis, 305 coosense, Cardium, 303, 308, 309

decoratum, 305
ermanensis, 311, 312
hannibali, 308, 309

coosense, Cerastoderma, 309
coosense, Keenocardium, 308
corbis, Calliostoma, 17, 18, 35

hatai, 310, 312 corbis, Cardium, 299, 305
hopkinsi, 308, 309 corbis, Clinocardium, 305
iwatense, 311, 312 corbis, Euchelus, 18
kljutschiense, 308, 309 corbis, Mirachelus, 16, 18, 19, 53, 54
lispum, 308, 309 corbis, Solariella, 18
makiyamae, 311, 313 Corbula
meekianum, 305 contracta, 223
mutuense, 311, 313 swiftiana, 223
myrae, 305 Corculum, 304
nanum, 305 coriacea, Corneolitorina, 110, 119
nomurai, 306 coriacea, Laevilitorina, 110, 117, 119, 123, 124
nuttallii, 299, 305, 306 Corneolitorina
okushirense, 308, 310 coriacea, 110, 119
padimeicum, 313 corneus, Planorbarius, 104, 105
praeblandum, 308, 310 corona, Melongena, 291
pristinum, 308, 310 coronata, Oxystele, 5
pseudofastosum, 306, 307 coronata, Trochus, 5
sachalinense, 313 coruscans, Cantharidus, 121, 123
salvationemense, 313 cossi, Sonorella, 201-206
schmidti, 311, 313 costalis, Margarites, 245
subdecussatum, 308, 310 costata, Cyrtopleura, 223
tokunagal, 306 costata, Siliqua, 247
uchidai, 307, 310 costulata, Ancistrobasis, 35, 51, 52
*clinocnemus, Mirachelus, 1, 16, “18, 19, 53, 55 costulata, Basilissa, 35, 51-53. 55
Cnidaria, 250 costulata, Seguenzia, 50
Cocculinoidea, 261 Couthouyella
Codakia striatula, 246
bella, 330-333 couthouyi, Admete, 245
Coleoida, 258, 271, 273, 278 Crassinella
columba, Aphrodite, 318 lunulata, 223
columba, Serripes, 318 Crassispira
Columbella cubana, 291
mercatoria, 291 Crassostrea
Colus virginica, 222, 236, 238
islandicus, 221, 245 crenata, Astarte, 213, 215, 225
pubescens, 221, 245 Crenella
pygmaeus, 221, 247 decussata, 246
spitzbergensis, 245 faba, 246
stimpsoni, 221, 247 fragilis, 222
ventricosus, 247 glandula, 214, 216, 221, 247
comoxense, Cardium, 312 Crepidula
comoxense, Ciliatocardium, 312 aculeata, 224

concava, Terebra, 224 fornicata, 215, 216, 222, 235, 248

plana, 235
crispata, Zirfaea, 221, 234, 239, 247
cronkhitei, Discus, 201-206
Crucibulum

Striatum, 215, 216, 222, 248
Crustacea, 109, 264
Cryptodonta, 264
cryptospira, Teinostoma, 223
*Ctenidiobranchia, *264, 270
cubana, Crassispira, 291
cubana, Gaza, 24, 54, 55
cubanum, Calliostoma, 31, 54
Cucullaea, 79
Cucullaeidae, 79
cucumariae, Diacolax, 121, 123
Cumingia

tellinoides, 222
cuneata, Anadara, 194
cuneata, Rangia, 240
Cuspidaria

glacialis, 246

obesa, 225

rostrata, 225
Cuspidariacea, 263
Cuspidarioidea, 264
Cyclina, 303
Cyclobranchia, 261
Cyclocardia

borealis, 213, 216, 221, 234, 237, 247
Cyclomya, 255
Cyclopecten

nanus, 223
Cylichna

linearis, 221
Cylichnella

bidentata, 224, 248

canaliculata, 248
Cyphoma

gibbosum, 290
Cypraea

acicularis, 290

cervus, 290

cinerea, 290

spurca, 290
Cypraecassis

testiculus, 290
Cyrtodaria

siliqua, 221, 234, 247
Cyrtodontacea, 79
Cyrtonellina, 255
Cyrtopleura

costata, 223
Cyrtosoma, 267
Cystoclonium

obtusangulum, 110
daedala, Gaza, 23
dalli, Inodrillia, 223
dallianum, Epitonium, 223
dawsoni, Cardium, 310, 312
dawsoni, Ciliatocardium, 310, 312
dealbata, Odostomia, 222
deauratum, Mesodesma, 247
decemcostata, Neptunea, 233, 238
decoratum, Cardium, 299, 305
decoratum, Clinocardium, 305

INDEX, VOL. 19 341

decussata, Crenella, 246
decussata, Oenopota, 245
deichmannae, Lischkeia, 15-17
delicatula, Basilissa, 50
delicatula, Seguenzia, 50
delphinodonta, Nucula, 246
deltoidea, Thais, 291
Dendronotina, 262
Dentaliida, 268, 271
Dentalium
eboreum, 224
dentifera, Calliostoma, 34
dentifera, Dentistyla, 35, 54, 55
dentifera, Solariella, 35
dentiferum, Antillachelus, 35
dentiferum, Calliostoma, 35
dentiferum, Dentistyla, 35, 36
dentiferus, Antillachelus, 35
dentiferus, Euchelus, 35
Dentistyla, 4, 34, 37
asperrima, 34, 35 53, 55
asperrimum 34-36
dentifera, 35, 54, 55
dentiferum, 35, 36
sericifilum, 35
depressa, Ancistrobasis, 51, 52
depressa, Basilissa, 51, 52
depressa, Machaeroplax, 37, 38
depressa, Margarita, 37, 39
depressa, Solariella, 37-39
depressus, Bulinus, 154
dermestinum, Vexillum, 291
Desmarestia, 110, 116
anceps, 110
menziesii, 110
Desmodonta, 263
despecta, Neptunea, 234, 238, 247
Diacolax
cucumariae, 121, 123
Diasoma, 267
Dibranchiata, 265
Didacna, 298
Dinocardium, 297-299
robustum, 223, 299
Diodora
tanneri, 222
Diplodonta
soror, 224
verrilli, 224
directus, Ensis, 215, 216, 222, 332
discors, Musculus, 246
Discosorida, 266, 271
discula, Basilissa, 50-53, 55
discula, Fluxina, 32, 50
discula, Planitrochus, 51
disculus, Planitrochus, 50
Discus
cronkhitei, 201-206
discus, Dosinia, 223
dislocata, Terebra, 223
Distorsio
clathrata, 224
Ditremata, 262
Divaricella, 333
quadrisulcata, 223

342

Docoglossa, 261, 270
Donax

vittatus, 329
Doridacea, 273, 278
Doryteuthis, 280

plei, 279
Dosinia

discus, 223
duplicata, Neverita, 235, 236, 248
duplicatus, Neverita, 330
duplicatus, Polinices, 223, 290, 330, 332
Dymares, 25
eboreum, Dentalium, 224
eburneola, Marginella, 224
echinatum, Calliostoma, 27, 28, 33, 53, 55
Echinodermata, 109
*Echinogurges, 1, 4, *20, 21, 23

anoxia, 53, 55

anoxius, 20, 22

clavatus, 9, 20, 22, 53-55

rhysus, 9, 20-23, 54, 55

tubulatus, 22, 23, 53, 55
Ectocochlia, 265
edentula, Cardium, 318
edentulum, Serripes, 318
edulis, Mytilus, 233, 234, 236, 238, 247
elegans, Propebela, 247
elegantula, Turbonilla, 222
Ellesmerocerida, 266, 271
elliptica, Astarte, 246
Ellobiidae, 261
Elmerlinia, 28

javanicum, 34

jujubinum, 28, 34
elodes, Stagnicola, 153, 154
Emarginula

fissura, 238
Endocerida, 266, 271
Endocochlia, 265
Ensis

directus, 215, 216, 222, 332
Eoplacophora, 253
Epitonium

championi, 223

dallianum, 223

greenlandicum, 245

pourtalesi, 223
equestris, Ostrea, 224
ermanensis, Ciliatocardium, 311, 312
ermanensis, Clinocardium, 311, 312
erosus, Tachyrhynchus, 245
Ervilia

concentrica, 224
esutoruense, Cerastoderma, 303
esutoruense, Laevicardium, 303
etheringtoni, Cerastoderma, 303
etheringioni, Laevicardium, 303
Euchelus, 4, 17, 18

corbis, 18

dentiferus, 35

guttarosea, 16, 17, 53, 55
Eucrassatella

speciosa, 224
euglyptum, Calliostoma, 55

MALACOLOGIA

Eumargarita, 4, 46

rotella, 49
Eunaticina, 330
Euspira

catena, 330

nitida, 330
euspira, Bathymophila, 5-7
euspira, Margarita, 5
euspira, Margarites, 1, 5-7, 54, 55
euspira, Umbonium, 5
euspirus, Bathymophila, 5
euspirus, Margarites, 5
Eutaxodonta, 264
Euthyneura, 16, 261
Eutrochus

alternatus, 28

cinctellum, 32

jujubinum, 28

perspectivum, 28

rawsoni, 28

sayanum, 31

tampaensis, 28
excavata, Tegula, 55
exoleta, Turritella, 223
expansus, Serripes, 317, 318
faba, Crenella, 246
fabricii, Cardium, 317, 318
fabricii, Serripes, 317, 318
fajumensis, Trisidos, 78
fasciata, Tegula, 55, 291
fascinans, Calliostoma, 55
Fasciolaria, 293

hunteria, 290

lilium, 290

tulipa, 290, 294
fastosum, Cardium, 308, 309
fastosum, Keenocardium, 308
Ferrissia, 97

rivularis, 97
Filibranchia, 264
filogyra, Margarita, 25
filosa, Lucinoma, 222
Firoloida, 74
fischeri, Gaza, 24, 53, 55
fissura, Emarginula, 238
Fissurellidae, 260
flammea, Cassis, 291
flavus, Limax, 103
flexuosa, Thyasira, 234, 247
floralia, Olivella, 224
fluctifraga, Chione, 187
fluctuosa, Liocyma, 246
fluviatilis, Ancylus, 103, 106
Fluxina, 25, 32, 51

brunnea, 32

discula, 32, 50
fontinalis, Physa, 103, 105
fornicata, Crepidula, 215, 216, 222, 235, 248
forskali, Pyrgophysa, 153
fragile, Periploma, 246
fragilis, Crenella, 222
Fragum

fragum, 331, 332
fragum, Fragum, 331, 332

INDEX, VOL. 19 343

fucanum, Cardium, 308, 309
fucanum, Keenocardium, 308
Fucus, 240
fujinensis, Mactra, 318
fujinensis, Serripes, 318
fulgurans, Nerita, 291
fulminatus, Pitar, 224
Fulvia, 297-299, 303

kurodai, 315

nipponica, 315, 316
Fuscocardium, 297, 300, 302, 305, 306

braunsi, 306, 307

nomurai, 306

ovata, 306

pseudofastosum, 306

tokunagai, 306
Gafrarium

pectinatum, 331, 332

tumidum, 331
galatheae, Neopilina, 254
galea, Tonna, 224
*Galeroconcha, 253, *254, 255, 257, 258, 267, 269,

210 273, 278
gallicum, Cardium, 303
gallina, Chamelea, 185, 189
Gastrodeuteia, 263
Gastropoda, 4, 63, 64, 73, 87, 103-127, 248, 254—
259, 266-270, 289

Gastroproteia, 263
Gaza 3, 4, 23, 46

cubana, 24, 54, 55

daedala, 23

fischeri, 24, 53, 55

rotella, 46

sericata, 25

Superba, 24, 54, 55

watsoni, 25, 53, 55
Gemma

gemma, 191, 194, 222
gemma, Gemma, 191, 194, 222
geversianus, Trophon, 123
gibba, Philine, 109
gibbosa, Plicatula, 224
gibbosum, Cyphoma, 290
gibbus, Argopecten, 223, 248
Gigartina, 115

apoda, 110
glabra, Marsenina, 245
glabrata, Biomphalaria, 103
glaciale, Buccinum, 245
glacialis, Cuspidaria, 246
glacialis, Pandora, 246
glandula, Crenella, 214, 216, 221, 247
glaucum, Cerastoderma, 298
globosus, Bulinus, 147
globosus, Physopsis, 147
Glossaulax, 330
Glycymerididae, 79
Glycymeris, 77, 79, 80, 83, 84
glyptus, Aequipecten, 223, 248
Goniatitida, 271
gouldiana, Pandora, 221, 235, 247
gouldii, Propebela, 247
grandifolius, Himantothallus, 110
granulata, Cardita, 233, 234

granulata, Poromya, 225
granulatum, Phalium, 224
Granulina

ovuliformis, 224
greenlandicum, Epitonium, 245
groenlandica, Volutomitra, 245
groenlandicum, Aphrodite, 318
groenlandicum, Cardium, 316, 318
“groenlandicum, Cardium,” 233
groenlandicum, Serripes, 316, 318
groenlandicus, Cardium, 317, 318
groenlandicus, Margarites, 245
groenlandicus, Serripes, 238, 246, 301, 312, 317-

320

grus, Chione, 191, 224
gualteriana, Natica, 330, 332
gualteriana, Naticarius, 330
guttarosea, Euchelus, 16, 17, 53, 55
guttata, Marginella, 290
Gymnomorpha, 260-262, 270, 273, 278
Gymnophila, 262
Gymnosomata, 261
gyrina, Physa, 97, 98
Habecardium, 298
haboroensis, Mactra, 319
haboroensis, Serripes, 319
haematobium, Schistosoma, 147
Haliotidae, 260
Haliotis, 257
hamiltonense, Cardium, 315
hamiltonense, Profulvia, 315
hamiltonense, Serripes, 315
hamiltoni, Macquariella, 121, 123
Haminoea

solitaria, 238
hancocki, Buccinum, 238
hannibali, Clinocardium, 308, 309
hannibali, Keenocardium, 308
hanpeizanense, Cardium, 303
hanpeizanense, Trachycardium, 303
hanzawai, Cardium, 303
hanzawai, Cerastoderma, 303
Haplotrema, 144
harpularia, Oenopota, 221, 245
harrimani, Papyridea, 302, 314, 315
harrimani, Profulvia, 315, 316
hassler, Calliostoma, 34
hataii, Ciliatocardium, 310, 312
hataii, Clinocardium, 310, 312
hataii, Serripes, 317
hayesii, Cardium, 312
hayesii, Ciliatocardium, 312
Hecuba, 193
Helcionellacea, 253
Helcionellina, 255
Helicidae, 103
helicinus, Margarites, 245
helicinus, Trochus, 4
Helisoma, 97

anceps, 97

campanulatum, 97

trivolvis, 97, 98
Helix, 103, 104, 106

pomatia, 103, 144
Helminthoglypta, 143, 144

344 MALACOLOGIA

hendersoni, Calliostoma, 30, 54, 55 Ischyriniida, 264, 265, 271
hendersoni, Kombologion, 30 islandica, Amauropsis, 245
hendersoni, Leiotrochus, 30 islandica, Arctica, 213, 215, 221, 234, 236, 239,
*Heptaplacota, “253, 258, 259, 265, 266, 270, 272, 247
278 islandica, Chlamys, 234, 236, 238, 247
heros, Lunatia, 214, 216, 221, 235, 237, 246 islandicum, Ciliatocardium, 312
Heterodonta, 264, 270 islandicus, Colus, 221, 245
Heteropoda, 63-76 Isofilibranchia, 264
*Heterotecta, 257, 259, “268, 269, 270, 272, 278 iwasiroense, Cardium, 308
Hiatella iwasiroense, Cerastoderma, 309
arctica, 225 iwasiroense, Keenocardium, 308
Himantothallus iwatense, Ciliatocardium, 311, 313
grandifolius, 110 iwatense, Clinocardium, 311, 313
Hippuritoidea, 271 Jacinthinus, 25
hizenense, Cardium, 303 japonica, Serripes, 318, 319
hizenense, Cerastoderma, 303 javanicum, Calliostoma, 34, 55
hondoensis, Solaricida, 7 javanicum, Elmerlinia, 34
hondoensis, Solariella, 7 jeanneae, Calliostoma, 31, 54
hopkinsi, Clinocardium, 308, 309 Jinonicellina, 271
hopkinsi, Keenocardium, 308 jobanicum, Cardium, 303
hudsoniense, Cardium, 304 jobanicum, Laevicardium, 303
hunteria, Fasciolaria, 290 jousseaumei, Bulinus, 154
Hyalina jujubinum, Calliostoma, 1, 28, 29, 34, 53, 55
avena, 290 jujubinum, Elmerlinia, 28
veliei, 223 jujubinum, Eutrochus, 28
hyalina, Lyonsia, 216, 223, 238 jujubinum, Leiotrochus, 28
Hydrobia jujubinus, Trochus, 28
totteni, 246 jujubinus, Zizyphinus, 28
Hyolitha, 272 kamtschaticus, Serripes, 317, 319
Hypanis, 298 Katelysia, 191, 193
Hypterita, 330 marmorata, 189, 191
Hysteroconcha, 193 Keenocardium, 297, 300-304, 307
icelandicum, Cardium, 312 andoi, 308
illecebrosus, Illex, 222 arakawae, 308
Illex blandum, 308
illecebrosus, 222 boreale, 308
llyanassa buelowi, 308
obsoleta, 222, 248 californiense, 307-310
ilyina, Serripes, 317, 319 fastosum, 308
immaculatus, Polinices, 221, 246 fucanum, 308
imperialis, Calliostoma, 15 hannibali, 308
imperialis, Lischkeia, 15-17, 53, 55 hopkinsi, 308
imperialis, Margarita, 15 iwasiroense, 308
imperialis, Turcicula, 2, 16 kljutschiense, 308
incertae, Solariella, 45 lispum, 308
incisula, Oenopota, 245 okushirense, 308
inflata, Pandora, 224 praeblandum, 308
infundibulum, Calliotropis, 15 pristinum, 308
Inodrillia, 225 subdecussatum, 308
dalli, 223 uchidai, 307
*inornata, Microgaza, “47-49, 55 Kellia
inornata, Pandora, 247 suborbicularis, 246
intapurpurea, Chione, 193, 224 kinsimarae, Cardium, 303
integra, Physa, 97 kinsimarae, Trachycardium, 303
interrogatorium, Laevicardium, 309 kipenensis, Papyridea, 315
interrupta, Turbonilla, 222 kipenensis, Profulvia, 315, 316
iridea, Machaeroplax, 42 Kirengellida, 255
iridea, Margarita, 42, 43 kljutschiense, Clinocardium, 308, 309
iridea, Solariella, 42-44 kljutschiense, Keenocardium, 308
iridea, Suavotrochus, 42-44 Kombologion, 29
iris, Solariella, 37, 39 atlantis, 31
irradians, Argopecten, 237 bairdii, 29
irrorata, Littorina, 235 hendersoni, 30

Ischnochitonida, 253 psyche, 29

INDEX, VOL. 19

schroederi, 30
kovatschensis, Papyridea, 315
kovatschensis, Profulvia, 315
kurodai, Fulvia, 315
kurodai, Papyridea, 315
kurodai, Profulvia, 315
Kurtziella

cerina, 223, 248
lactea, Marginella, 290
lacteus, Polinices, 290
Lacuna, 231

pallidula, 246

vincta, 239, 240, 245
lacunella, Machaeroplax, 37, 38
lacunella, Margarita, 37
lacunella, Solariella, 37-39, 54, 55
Laevicardiinae, 297-299
Laevicardium, 297-299, 303, 304

esutoruense, 303

etheringtoni, 303

interrogatorium, 309

jobanicum, 303

laevigatum, 224

mortoni, 235

pantecolpatum, 303

pictum, 223

Squalidus, 320

ugllense, 311), 313
laevigatum, Laevicardium, 224
Laevilacunaria, 110, 117

antarctica, 110, 111, 116-119, 123, 125-127

bennetti, 110, 111, 117, 118, 123, 125, 126
Laevilitorina, 110, 117

caliginosa, 123

coriacea, 110, 117, 119, 123, 124
lamarcki, Carinaria, 63-76
Lamellaria, 260
Lamellibranchia, 109, 223
lamellosa, Machaeroplax, 37
lamellosa, Margarita, 40
lamellosa, Nucella, 294
lamellosa, Solariella, 2, 9, 37, 40, 42, 54, 55
lamellosa, Thais, 294
Laminaria, 239, 240
laperousii, Serripes, 318, 319
lapillus, Nucella, 234, 239, 247, 294
lapillus, Thais, 294
lata, Calliotropis, 9
lata, Margarita, 9
lata, Solaricida, 9
lata, Solariella, 11
Lateradulata, 265
lateralis, Mulinia, 222
latilirata, Chione, 224
leanum, Periploma, 221, 247
Leiotrochus

cinctellum, 33

hendersoni, 30

Jujubinum, 28

perspectivum, 28

rawsoni, 28

sayanum, 32
lens, Myrtea, 223
Lepeta

caeca, 245
Lepidopleurida, 253, 270
Lepidopleuridae, 251
Leptosarca, 115, 116, 118

simplex, 110
Leucozonia

ocellata, 291
lilium, Fasciolaria, 290
lima, Margarita, 13
lima, Trochus, 9, 13
Limatula

subauriculata, 225
limatula, Yoldia, 221, 234, 238, 247
Limax, 143, 144

flavus, 103
Limoidea, 264
Limopsacea, 79, 84
Limopsidae, 79, 84
Limopsis, 77-79

sulcata, 223, 248
linearis, Cylichna, 221
Liocyma

fluctuosa, 246
lioica, Abra, 223
Lipodonta, 264
Lirophora, 195
ischkela V2 т, 15

deichmannae, 15-17

imperialis, 15-17, 53, 55

monilifera, 15, 17
lispum, Clinocardium, 308, 309
lispum, Keenocardium, 308
Lissarca, 78
lissocona, Calliotropis, 8, 14, 53, 54
lissocona, Machaeroplax, 14
lissocona, Margarita, 14
lissocona, Solaricida, 8, 14
Litharca, 77, 79

345

littorea, Littorina, 234, 236, 237, 239, 240, 246

Littorina, 63, 73-75, 294
angulifera, 291, 292
caliginosa, 123
irrorata, 235
littorea, 234, 236, 237, 239, 240, 246
obtusata, 123, 234, 239, 240, 246
saxatilis, 239, 245
ziczac, 291
Littorinoidea, 74
lividomaculata, Tegula, 55, 291
Llandeilochiton, 253
Loboconcha, 257, 267
Loliginidae, 279, 286
Loligo, 280, 286
opalescens, 279-286
pealei, 222, 279-287
plei, 279-287
vulgaris, 286
Lolliguncula, 280, 287
brevis, 279-288
Loricata, 253, 258, 265, 270
Loxocardium, 297
lubrica, Machaeroplax, 42
lubrica, Margarita, 42
lubrica, Solariella, 5, 42-44, 53, 55

346

lubrica, Suavotrochus, 42-44
Lucina

nassula, 224

radians, 224
Lucinidae, 329, 330
Lucinoma

filosa, 222
lunata, Mitrella, 216, 223, 248
Lunatia

heros, 214, 216, 221, 235, 237, 246

pallida, 221, 245

triseriata, 214, 216, 221, 247
lunatus, Trochus, 28
lunulata, Crassinella, 223
Lymnaea, 87-101, 104, 106, 144, 145

catascopium, 87-101

palustris, 96

peregra, 96-98

stagnalis, 96, 98, 105, 153, 154

trunculata, 96
Lymnaeidae, 87-101, 103, 153
Lymnocardiidae, 298
Lymnocardiinae, 298
Lyonsia

arenosa, 246

hyalina, 216, 223, 238
lyrata, Neptunea, 233, 238, 247
Lyrodesmatina, 264
Machaeroplax, 37

aegleis, 13

affinis, 37

anoxia, 21

depressa, 37, 38

iridea, 42

lacunella, 37

lamellosa, 40

lissocona, 14

lubrica, 42

rhina, 13

tiara, 45
Macluritoidea, 261
Macoma

balthica, 225, 234, 236, 238, 247

calcarea, 246

tenta, 216, 223
Macquariella

hamiltoni, 121, 123
macquariensis, Nacella, 121, 123
macquariensis, Patinigera, 121, 123
Mactra

fujinense, 318

haboroensis, 319

makiyamai, 321

radiata, 320
maculata, Margarita, 37
maculata, Solariella, 9, 37
maculosa, Tonna, 290

magellanicus, Placopecten, 210, 221, 235, 237,247

makiyamae, Ciliatocardium, 311, 313
makiyamae, Clinocardium, 311, 313
makiyamai, Mactra, 321

makiyamai, Serripes, 321
makiyamai, Yagudinella, 321
maltbiana, Trivia, 224, 291
Mammilla, 330

MALACOLOGIA

Manotrochus, 25
Maoricardium, 297
Margarella,

antarctica, 110, 111, 113, 114, 123, 124

Margarita, 1, 4, 7, 9, 15, 20, 37

actinophora, 14

aegleis, 7, 9, 13, 20, 40

amabilis, 40, 42

asperrima, 34, 35

cinerea, 114, 123

clavata, 20

clavatus, 1, 20

depressa, 37, 39

euspira, 5

filogyra, 25

imperialis, 15

iridea, 42, 43

lacunella, 37

lamellosa, 40

lata, 19

lima, 13

lissocona, 14

lubrica, 42

maculata, 37

nitens, 5

rhina, 13

rhysus, 21

scabriuscula, 45
margaritacea, Neotrigonia, 195
Margarites, 1, 4, 5, 37, 46

bairdi, 5-7, 54, 55

bairdii, 54

costalis, 245

euspira, 1, 5-7, 54, 55

euspirus, 5

groenlandicus, 245

helicinus, 245

olivaceus, 245

refulgens, 123
Margaritinae, 4, 7
Marginella

borealis, 222

eburneola, 224

guttata, 290

lactea, 290

pruniosum, 290

roscida, 223, 248
marica, Timoclea, 331, 332
marionae, Calliostoma, 55
marmorata, Katelysia, 189, 191
Marsenina

glabra, 245
matchgarense, Cardium, 311, 313
matchgarense, Cerastoderma, 311, 313
matchgarense, Ciliatocardium, 311, 313
matschigarica, Papyridea, 315
matschigarica, Profulvia, 315
Matthevia, 269
mazyckil, Chione, 184
meekianum, Cardium, 305
meekianum, Clinocardium, 305
Megayoldia

myalis, 233

thraciaeformis, 221, 233, 246
Melongena, 293

INDEX, VOL. 19 347

corona, 291
melongena, 291
melongena, Melongena, 291
menziesii, Desmarestia, 110
mercatoria, Columbella, 291
Mercenaria, 189-195
campechiensis, 223
mercenaria, 157-159, 222, 223, 235
mississippiensis, 193
notata, 185
mercenaria, Mercenaria, 157-199, 222, 223, 235
Meretricinae, 193
Meretrix
meretrix, 188
meretrix, Meretrix, 188
Mesodesma
arctatum, 221, 237, 238, 247
deauratum, 247
Mesodon, 144
Mesogastropoda, 63, 64, 73-75, 261, 270
Michelinoceratites, 265
Microgaza, 1, 4, 37, 45, 46
*inornata, 1, “47-49, 55
rotella, 1, 45-49, 53, 55
vetula, 1, 46, 48, 49, 53, 55
Micropiliscus, 43
constricta, 41, 43, 45
Middendorffia
caprearum, 252
millepunctata, Natica, 330
minirosea, Ocenebra, 291
minuta, Nuculana, 246
minuta, Turtonia, 246
minutus, Trophon, 110, 119, 120
mirabilis, Ascoseira, 110
mirabilis, Partula, 129
mirabilis, Strigilla, 224
Mirachelus, 1, 4, 17-19
*clinocnemus, 1, 16, “18, 19, 53, 55
corbis, 16, 18, 19, 53, 55
mississippiensis, Mercenaria, 193
Mitrella
lunata, 216, 223, 248
ocellata, 290
rosacea, 245
Modiolus, 239
auriculatus, 330-332
modiolus, 213, 215, 216, 221, 234, 236, 239, 246

modiolus, Modiolus, 213, 215, 216, 221, 234, 236,

239, 246
Mollusca, 4, 249, 257, 266-268, 270-272, 278
Monadenia, 143, 144
monilifera, Lischkeia, 15, 17
moniliferus, Trochus, 15
Monodonta, 17

Monoplacophora, 254, 255, 258, 269, 270, 273,

278

Monostichoglossa, 261
Monotocardia, 260, 261
montagui, Astarte, 246
mooreana, Partula, 129
morrhuanus, Pitar, 221, 247
mortoni, Laevicardium, 235
Morula, 330

Mulinia
lateralis, 222
Multifariida, 255
multilineata, Parvilucina, 224
*multirestis, Solariella, 1, 38, *39, 53, 55
тигай, Serripes, 317, 319
Murchisonioidea, 261
Murex
pomum, 291
Muricacea, 330
Muricanthus, 330
muricatum, Vasum, 291
muricatus, Trophon, 123
Muricidae, 119
muscosus, Aequipecten, 224
Musculus
discors, 246
niger, 221, 246
mutica, Olivella, 223
mutuense, Cardium, 311, 313
mutuense, Ciliatocardium, 311, 313
mutuense, Clinocardium, 311, 313
Mya
arenaria, 188, 221, 234, 238, 247
truncata, 238, 246
myalis, Megayoldia, 233
myalis, Yoldia, 233, 234, 246
Myina, 264
Myopsida, 279
myopsis, Thracia, 246
myrae, Clinocardium, 305

Myrtea
lens, 223
Mytilidae, 330, 331
Mytilina, 264
Mytilus
edulis, 233, 234, 236, 238, 247
Nacella

concinna, 121, 123

macquariensis, 121, 123
nanum, Cardium, 305
nanum, Clinocardium, 305
nanus, Cyclopecten, 223
Nassarius

acutus, 223

albus, 224

trivittatus, 215, 216, 222

vibex, 216, 223, 248, 291
nassula, Lucina, 224
Natica

clausa, 221, 238, 245

gualteriana,330, 332

millepunctata, 330

pusilla, 222, 248
Naticarius

gualteriana, 330
Naticidae, 330
Nautilida, 271
Nautiloida, 254, 258, 265, 266, 271, 273, 278
Nautilus, 257, 265
Neaeromya, 225
Nematomenia

banyulensis, 252

protecta, 267

348

Nemocardium, 298
Neogastropoda, 119, 121, 261, 270
Neoloricata, 253

Neomeniina, 250

Neomenioidea, 250
Neomeniomorpha, 250, 252, 270

Neopilina, 254, 255, 257, 259, 261, 267, 268, 272,

278

galatheae, 254
Neotaxodonta, 264
Neotrigonia

margaritacea, 195
Neptunea, 238

decemcostata, 233, 238

despecta, 234, 238, 247

lyrata, 233, 238, 247
Nerita

fulgurans, 291

versicolor, 291
Neritacea, 260, 261
Neritopsina, 261, 270
Neverita

duplicata, 235, 236, 248

duplicatus, 330
nigamiensis, Serripes, 321
nigamiensis, Yagudinella, 321
niger, Musculus, 221, 246
nipponica, Fulvia, 315, 316
nipponica, Papyridea, 316
nipponica, Profulvia, 316
Niso

aeglees, 224
nitens, Margarita euspira, 5
nitida, Euspira, 330
nitida, Nitidella, 290
nitida, Polinices, 330
Nitidella

nitida, 290
noachina, Puncturella, 245
*nodai, Serripes, 297, 317, *319, 320
Nodilittorina

tuberculata, 291
Noetia, 77-79

ponderosa, 223, 248
Noetiidae. 79
nomurai, “Clinocardium,” 306
nomurai, Fuscocardium, 306
nomurai, Serripes, 321
nomurai, Yagudinella, 321
notabile, Cardium, 301, 320
notabile, Serripes, 301, 320
notabilis, Cardium, 322
notabilis, Serripes, 321, 322
notabilis, Yagudinella, 301, 321, 322
Notaspidea, 261, 270
notata, Mercenaria, 185
novaezelandiae, Barbatia, 83
noyamiana, Papyridea, 315, 316
noyamiana, Profulvia, 315
Nucella, 231, 239

lamellosa, 294

lapillus, 234, 239, 247, 294
nucleus, Planaxis, 291

MALACOLOGIA

Nucula

atacellana, 247

delphinodonta, 246

proxima, 222, 238, 248

tenuis, 238, 246
Nuculacea, 263
Nuculana

acuta, 223, 248

minuta, 246

pernula, 238, 246

tenuisulcata, 238, 246
Nuculida, 264, 270
Nudibranchia, 261, 270, 273, 278
nuttallii, Cardium, 299, 300, 305, 306
nuttallii, Clinocardium, 299, 305
obesa, Cuspidaria, 225
obscura, Solariella, 213, 215, 221, 245
obsoleta, llyanassa 222, 248
obtusangulum, Cystoclonium, 110
obtusata, Littorina, 123, 234, 239, 240, 246
occidentale, Calliostoma, 26, 246
occidentalis, Aporrhais, 245
ocellata, Leucozonia, 291
ocellata, Mitrella, 290
Ocenebra

minirosea, 291
ochotensis, Serripes, 317, 319
Octobrachia, 271
Octopoda, 271
Octopus, 286
Odostomia

cancellata, 223

dealbata, 222

smithii, 222
Oenopota

bicarinata, 221, 245

decussata, 245

harpularia, 221, 245

incisula, 245

pyramidalis, 245
okushirense, Clinocardium, 308, 310
okushirense, Keenocardium, 308
Oliva, 293

sayana, 224, 290
olivaceus, Margarites, 245
Olivella

biplicata, 332

floralia, 224

mutica, 223
Omalogyra

atomus, 246
Omalogyridae, 254
Onchidiacea, 262, 273, 278
Onchidiida, 270
Onchidiidae, 262
Oncocerida, 271
opalescens, Loligo, 270-286
operculata, Varicorbula, 224
Opisthobranchia, 74, 260-262, 270, 273, 278
Opisthopneumona, 262
Oreohelix, 144
orion, Calliostoma, 54, 55
Orthoceratoida, 258, 271

Orthocerida, 265, 271
Orthoceroida, 266, 273, 278
Ostrea
equestris, 224
Ostreoidea, 264
Otinidae, 261
ottoi, Calliotropis, 6, 9
ottoi, Trochus, 7, 9
ovalis, Anadara, 216, 223, 248
ovata, Clinocardium, 306, 307
ovata, Fuscocardium, 306
ovuliformis, Granulina, 224
Oxystele
coronata, 5
euspira, 5
oxytoma, Basilissa, 50
Pachytegmentaria, 252, 270
padimeicum, Ciliatocardium, 313
padimeicum, Clinocardium, 313
Palaeobranchia, 264, 270
Palaeocadmus, 265
Palaeoheterodonta, 264, 270
Palaeoloricata, 253
Palaeotaxodonta, 264
palatam, Quidnipagus, 331, 332
pallida, Lunatia, 221, 245
pallidula, Lacuna, 246
pallidus, Polinices, 238
Palliolum
striatum, 247
subimbrifer, 222
palustris, Lymnaea, 96-98
Panchione, 157, 158, 195
paphia, 158
Pandora
arenosa, 224
glacialis, 246
gouldiana, 221, 235, 247
inflata, 224
inornata, 247
trilineata, 224
Panomya
arctica, 246
pantecolpatum, Cardium, 303
pantecolpatum, Laevicardium, 303
paphia, Chione, 157-199
paphia, Panchione, 158
Papillicardium, 297
papyratium, Periploma, 221, 247
Papyridea, 297, 302, 303
angulata, 315
brooksi, 308, 312
harrimani, 302, 314, 315
kipenensis, 315
kovatschensis, 315
kurdodai, 315
matschigarica, 315
nipponica, 316
noyamiana, 315, 316
sakhalinensis, 315, 316
securiformis, 315, 316
sertunayana, 314, 315
utcholokensis, 315, 316
Parallelondontidae, 79

INDEX, VOL. 19

Partula, 129-146

aurantia, 131

mirabilis, 129

mooreana, 129

suturalis, 129-138, 142, 143, 145

taeniata, 129, 130, 138-145

tohiveana, 129
Parvicardium, 297, 298, 304
Parvilucina

multilineata, 224
Patella, 269
Patellacea, 260, 261
Patellina, 261
Patinigera

concinna, 121, 123

macquariensis, 121
pauperculum, Cardium, 297, 319, 320
pauperculum, Serripes, 319
pealeii, Loligo, 222, 279-288
Pecten

raveneli, 224
pectinatum, Gafrarium, 331, 332
Pectinibranchia, 261
Pectinoidea, 264
Pelagiellacea, 255
Pelecypoda, 258, 264, 265, 270
Pellilacunella

bennetti, 110, 117, 118
Pellilitorina, 115, 116, 125

pellita, 111, 114-116, 123, 125

setosa, 110, 111, 114-116, 123, 125
pellita, Pellilitorina, 111, 114-116, 123, 125
peregra, Lymnaea, 96-98
peregrinus, Trochus, 9
Pericalymma, 263
Periglypta

reticulata, 331
Periploma

fragile, 246

leanum, 221, 247

papyratium, 221, 247
pernula, Nuculana, 238, 246
perspectivum, Calliostoma, 28
perspectivum, Eutrochus, 28
perspectivum, Leiotrochus, 28
perspectivum, Sinum, 223, 248
perspectivus, Trochus, 28
Petricola

pholadiformis, 222
pfeifferi, Biomphalaria, 96
Phalium

granulatum, 224
Philine, 109

gibba, 109

quadrata, 221
Philinoglossoidea, 261
Philippia, 222
Philobrya, 78
Philobryidae, 84
phoebia, Astraea, 291
pholadiformis, Petricola, 222
Pholadoidea, 269
Pholadomyina, 264
Pholidoskepia, 252, 270

349

350 MALACOLOGIA

Photinastoma, 26
Photinula, 26
Phragmoteuthida, 265, 271
phrygium, Aequipecten, 223, 248
Phyllomenia, 250
Physa, 97, 103-106

fontinalis, 103, 105

gyrina, 97, 98

integra, 97
Physidae, 96, 103
Physopsis

globosus, 147
pica, Cittarium, 55, 291
pictum, Laevicardium, 223
pinnulatum, Cerastoderma, 221, 235, 238, 247
Pisania

auritula, 291
Pitar

fulminatus, 224

morrhuanus, 221, 247

rudis, 191
Placopecten

magellanicus, 210, 221, 235, 237, 247
Placophora, 249-253, 255, 257-259, 261, 266-

270, 272, 278

Plagiocardium, 297
plana, Crepidula, 215, 216, 222, 235
Planaxis

nucleus, 291
Planitrochus, 50, 51

discula, 51

disculus, 50
Planorbarius, 103, 104

corneus, 104, 105
Planorbidae, 96, 103, 147
Planorbis, 97

contortus, 97
planorbis, Skeneopsis, 245
plectrum, Buccinum, 238, 245
plei, Doryteuthis, 279
plei, Loligo, 279, 288
Pleuromeris

tridentata, 224
Pleurotomariidae, 260, 261
plicatilis, Velutina, 245
Plicatula

gibbosa, 224
Plocamium

secundatum, 110
Polinices, 293, 330, 332

catena, 330

duplicatus, 223, 290, 330, 332

immaculatus, 221, 246

lacteus, 290

nitida, 330

pallidus, 238

tumidus, 329, 330, 332
polita, Turbonilla, 221
Polycera, 107
Polychaeta, 109
Polygyra, 144
polynyma, Spisula, 233, 246
Polyplacophora, 106, 253
Polyplaxiphora, 253

pomatia, Helix, 103, 144
pomum, Murex, 291
ponderosa, Noetia, 223, 248
Poromya

granulata, 225
Poromyacea, 263
Poromyida, 264, 271, 273, 278
Poromyoidea, 264
Portlandia

arctica, 238
pourtalesi, Epitonium, 223
pourtalesi, Solariella, 1, 9, 40-42, 53, 55
praeblandum, Clinocardium, 308, 310
praeblandum, Keenocardium, 308
Praecardiida, 264, 270
pristinum, Clinocardium, 308, 310
pristinum, Keenocardium, 308
Profulvia, 302, 303, 314

angulata, 315

hamiltonense, 315

harrimani, 315, 316

kipenensis, 315, 316

kovatschensis, 315

kurodai, 315

matschigarica, 315

nipponica, 316

noyamiana, 315

sakhalinensis, 315, 316

securiformis, 315, 316

sertunayana, 315, 316

utcholokensis, 315, 316
Profulviini, 302, 314
Propebela

elegans, 247

gouldii, 247

Sarsi, 247

turricula, 245
Prosipho, 121, 122
Prosobranchia, 4, 64, 73, 74, 88, 262, 270
protecta, Nematomenia, 267
Protobranchia, 263
Protothaca, 186, 188, 191, 194, 195, 303
prototortuosum, Trisidos, 78
protractus, Serripes, 320
proxima, Nucula, 222, 238, 248
pruniosum, Marginella, 290
Prunum, 225
Pseudoctenodonta, 264
pseudofastosum, Cardium, 306
pseudofastosum, Clinocardium, 306, 307
pseudofastosum, Fuscocardium, 306
Pseudolamellibranchia, 264
Pseudomyicola spinosus, 188
Pseudophycodrys, 110, 115, 116, 118
psyche, Calliostoma, 29, 30, 53-55
psyche, Kombologion, 29
Pteriina, 264
Pterioidea, 264
Pteriomorpha, 264, 270
Pteriomorphia, 77
Pterotrachea, 63, 74-76
Pterotracheidae, 63, 74
pubera, Chione, 193
pubescens, Cardium, 311, 313

INDEX, VOL. 19

pubescens, Ciliatocardium, 311, 313
pubescens, Colus, 221, 245
puchlense, Cardium, 303
pulcher, Calliostoma, 26
pulcher, Trochus, 26
pulchrum, Calliostoma, 1, 26, 27, 31, 53, 55
pullastra, Venerupis, 191
Pulmonata, 96, 107, 260-262, 270, 273, 278
Puncturella, 225

noachina, 245
pusilla, Nactica, 222, 248
pygmaeus, Colus, 221, 247
pyramidalis, Oenopota, 245
Pyramidella

unifasciata, 223
Pyramidellimorpha, 270
Pyrgophysa,

forskali, 153
quadrata, Philine, 221
quadricarinatus, Trochus, 17
quadrisulcata, Divaricella, 223
Quidnipagus

palatam, 331, 332
radians, Lucina, 224
radiata, Mactra, 320
radiata, Serripes, 320
Rangia

cuneata, 240
Rathousiidae, 262
raveneli, Pecten, 224
raveneli, Spisula, 236
rawsoni, Calliostoma, 28
rawsoni, Eutrochus, 28
rawsoni, Leiotrochus, 28
refulgens, Margarites, 123
regalis, Calliotropis, 7-9
reticulata, Periglypta, 331
reticulata, Turbonilla, 223
Rhabdopitaria, 192-194
rhina, Calliotropis, 9, 12, 13, 20, 42, 54, 55
rhina, Machaeroplax, 13
rhina, Margarita, 13
rhina, Solaricida, 12, 13
rhina, Solariella, 13
rhina, Trochus, 13
Rhodopacea, 262, 273, 278
Rhodophyceae, 110
Rhodopida, 270
Rhodopidae, 262
rhomboideum, Cardium, 303
rhyssa, Ancistrobasis, 51
rhyssa, Basilissa, 51, 53, 55
rhyssa, Solariella, 21
rhysus, Echinogurges, 9, 20-23, 54, 55
rhysus, Margarita, 21
rhysus, Solariella, 21
rhysus, Trochus, 21
Ribeiriida, 265, 271
Ribeiroidea, 264
rigida, Atrina, 224
Rissoella, 260
rivularis, Ferrissia, 97
robusta, Arcopagia, 330-332

robustum, Dinocardium, 223, 299
rosacea, Mitrella, 245
roscida, Marginella, 223, 248
roseolum, Calliostoma, 26-28, 54, 55
Rossia, 225

tenera, 222
rostrata, Cuspidaria, 225

Rostroconchia, 258, 264, 265, 267, 271,

278

rotella, Callogaza, 45, 46
rotella, Eumargarita, 49
rotella, Gaza, 46
rotella, Microgaza, 1, 45-49, 53, 55
rudis, Pitar, 191
rudis, Venus, 191
rustica, Thais, 291, 294
Saccoglossa, 261, 270
sachalinense, Ciliatocardium, 313
sachalinense, Clinocardium, 313
Sacoglossa, 261
sakhalinensis, Papyridea, 315, 316
sakhalinensis, Profulvia, 315, 316
Salterella, 271
salvationemense, Ciliatocardium, 313
salvationemense, Clinocardium, 313
Samoana, 129
sapidum, Calliostoma, 30, 53, 55
sapotilla, Yoldia, 213, 215, 221, 246
sarcodum, Calliostoma, 55
sarsi, Propebela, 247
saxatilis, Littorina, 239, 245
sayana, Oliva, 224, 290
sayanum, Calliostoma, 31, 32, 53, 55
sayanum, Eutrochus, 31
sayanum, Leiotrochus, 32
scabriuscula, Margarita, 45
scabriuscula, Solariella, 45
scalariforme, Buccinum, 245
*Scanochitonida, *253, 270
Scaphopoda, 257, 258, 266-269, 271
scapoosense, Cardium, 303
scapoosense, Cerastoderma, 303
Scenella, 255
Schistosoma

haematobium, 147
schmidti, Ciliatocardium, 311, 313
schmidti, Clinocardium, 311, 313
schroederi, Calliostoma, 30, 31, 53, 55
schroederi, Kombologion, 30
Scissulina, 331
Scissurellidae, 253
Scutobranchia, 261

Scutopoda, 249, 257, 259, 266, 268-270, 272, 278

Scutopus, 250
secundatum, Plocamium, 110
securiformis, Papyridea, 315, 316
securiformis, Profulvia, 315, 316
sedis, Solariella, 45
Seguenzia, 50

carinata, 50

costulata, 50

delicatula, 50

trispinosa, 15

352 MALACOLOGIA

Seguenziidae, 50
Semele
bellastriata, 224
Sepia, 286
Sepiida, 271
Sepioteuthis, 286
Septemchiton, 253
Septemchitonida, 253, 270, 272
septentrionalis, Thracia, 221, 246
Septibranchia, 263, 264, 271, 273, 278
sericata, Gaza, 25
sericifila, Calliostoma, 34
sericifilum, Dentistyla, 35
Serripedini, 301, 302, 316
Serripes, 298, 299, 301-303, 316, 317, 320
album, 318
boreale, 318
columba, 318
edentulum, 318
expansus, 317, 318
fabricii, 317, 318
fujinensis, 318
groenlandicum, 316, 318
groenlandicus, 238, 246, 301, 312, 317-320
haboroensis, 319
hamiltonense, 315
hatai, 317-319
ilyina, 317, 319
japonica, 318, 319
kamtschaticus, 317, 319
laperousii, 318, 319
makiyamai, 321
тигай, 317, 319
nigamiensis, 321
*nodai, 297, 317, *319, 320
notabile, 301, 320
notabilis, 321, 322
ochotensis, 317, 319
pauperculum, 319
protractus, 320
radiata, 320
shiobaraensis, 317, 320
squalidus, 317, 320
titthus, 320
triangularis, 317, 320
unciangulare, 320
uvutschensis, 317, 320
yokoyami, 322
sertunayana, Papyridea, 314, 315
sertunayana, Profulvia, 315, 316
setosa, Pellilitorina, 110, 111, 114-116, 123, 125
shimotokuraense, Vasticardium, 303
shinjiense, Cardium, 311, 313
shinjiense, Ciliatocardium, 311, 313
shiobaraensis, Serripes, 317, 320
Siliqua
costata, 247
siliqua, Cyrtodaria, 221, 234, 247
simplex, Anomia, 223
simplex, Leptosarca, 110
Sinuitopsina, 255
Sinuitopsis
acutilira, 253
Sinum, 330

perspectivum, 223, 248
Siphonoconcha, 257, 267
Siphonodentaliida, 268, 271
Siphonopoda, 257, 258, 261, 265-268, 269, 271,

273, 278
Skeneopsis

planorbis, 245
smithii, Odostomia, 222
snatolense, Acanthocardia, 311, 313
snatolense, Cardium, 311, 313
snatolense, Ciliatocardium, 311, 313
snatolensis, Acanthocardia, 313
snatolensis, Cardium, 313
snatolensis, Ciliatocardium, 313
Solaricida, 7, 8

actinophora, 12

aeglees, 8

aegleis, 9

calatha, 9, 10, 12

hondoensis, 7

lata, 9

lissocona, 8, 14

rhina, 12, 13
Solariella, 4, 18, 20, 34, 37, 46

actinophora, 14

aegleis, 7, 11, 13, 20

affinis, 36

amabilis, 1, 36, 37, 40, 42

anoxia, 21

asperrima, 34

calatha, 11, 41

clavata, 20

constricta, 41, 43, 45, 53, 55

corbis, 18

dentifera, 35

depressa, 37, 39

hondoensis, 7

incertae, 45

iridea, 42-44

iris, 37, 39

lacunella, 37-39, 54, 55

lamellosa, 2, 9, 37, 40-42, 54, 55

lata, 11

lissocona, 14

lubrica, 5, 42-44, 53, 55

maculata, 9, 37

*multirestis, 1, 38, “39, 53, 55

obscura, 213, 215, 221, 245

pourtalesi, 1, 9, 40—42, 53, 55

rhina, 13

rhyssa 21

rhysus, 21

scabriuscula, 45

sedis, 45

tiara, 40, 44, 45, 53, 55

tubula, 39, 41, 53, 55

tubulata, 23
Solariellinae, 1, 4, 7, 37
Solariellopsis, 7
Solariidae, 32
“Solarium”

turbinoides, 9
Solemya

borealis, 247

Solemyacea, 263
Solemyida, 264, 270

Solenogastres, 106, 249, 253, 257-259, 266-270,

272, 278

Soleolifera, 262, 270, 273, 278
solidissima, Spisula, 221, 236-238
solitaria, Haminoea, 238
Sonorella

baboquivariensis, 201-206

cossi, 201-206
sookense, Cardium, 303
soror, Diplodonta, 224
speciosa, Eucrassatella, 224
Sphaerorthoceridae, 265
spinosus, Pseudomyicola, 188
Spisula

polynyma, 233, 246

raveneli, 236

solidissima, 221, 236-238
spitzbergensis, Colus, 245
springeri, Calliostoma, 32
spurca, Cypraea, 290
squalidus, Cardium, 320
squalidus, Laevicardium, 320
squalidus, Serripes, 317, 320
squamifera, Tellina, 224
squamula, Anomia, 221, 234, 239, 247
stagnalis, Lymnaea, 96, 98, 105, 153, 154
Stagnicola elodes, 153, 154
Stenothecoida, 269
Stenotrema, 143
Sterrofustia, 252, 270
Stigmaulax, 330
Stilifer

stimpsoni, 223, 248
stimpsoni, Colus, 221, 247
stimpsoni, Stilifer, 223, 248
Streptoneura, 261
striatula, Couthouyella, 246
striatula, Venus, 185
striatum, Crucibulum, 215, 216, 222, 248
striatum, Palliolum, 247
Strigilla

mirabilis, 224
Strophocheilus, 144
Stutchburyi, Austrovenus, 157-199
Stylommatophora, 261, 270
Stylotrochus, 25
Suavotrochus, 42

iridea, 42-44

lubrica, 42-44
subaequilatera, Astarte, 213, 215, 225
subauriculata, Limatula, 225
subdecussatum, Clinocardium, 308, 310
subdecussatum, Keenocardium, 308
subimbrifer, Palliolum, 222, 247
suborbicularis, Kellia, 246
subumbilicatum, Calliostoma, 29
succincta, Chione, 187
sulcata, Limopsis, 223, 248
superba, Basilissa, 49, 50
superba, Gaza, 24, 54, 55
suturale, Calliostoma, 26
suturalis, Partula, 129-138, 142, 143, 145

INDEX, VOL. 19

swiftiana, Corbula, 223
Sybaritica, Tellina, 224
Systellommatophora, 262
“tabulata,” Echinogurges, 23
Tachyrhynchus

erosus, 245

taeniata, Partula, 129, 130, 138-145

tampaensis, Calliostoma, 28
tampaensis, Eutrochus, 28
tampaensis, Trochus, 28
tanneri, Diodora, 222
Tapetinae, 185, 193, 195
taracaicum, Cardium, 304
Tarphycerida, 271
tecta, Astraea, 291
Tegula, 53

excavata, 55

fasciata, 55, 291

lividomaculata, 55, 291
Teinostoma

cryptospira, 223
tejedori, Astele, 32
tejedori, Calliostoma, 32
Teletremata, 262
Tellina

aequistriata, 224

agilis, 222, 236

alternata, 224

squamifera, 224

sybaritica, 224

tenella, 224

versicolor, 216, 224
Tellinidae, 329-331
tellinoides, Cumingia, 222
Telobranchiata, 252
tenella, Tellina, 224
tenera, Rossia, 222
tenta, Macoma, 216, 223
Tentaculita, 271
tenuis, Nucula, 238, 245

tenuisulcata, Nuculana, 238, 246

Terebra
concava, 224
dislocata, 223
Tergomya, 255
terrae-novae, Buccinum, 238
Testaria, 257, 272
testiculus, Cypraecassis, 290

testudinalis, Acmaea, 239, 245

Tetrabranchiata, 265

Teuthida, 271

Thais, 330
deltoidea, 291
lamellosa, 294
lapillus, 294
rustica, 291, 294

Thecosomata, 261

Thelyssa, 50

Thracia
conradi, 221, 235, 247
myopsis, 246
septentrionalis, 221, 246
Thyasira

flexuosa, 234, 247

354

trisinuata, 222

thraciaeformis, Megayoldia, 221, 233, 246

tiara, Calliostoma, 18, 45
tiara, Machaeroplax, 45
tiara, Solariella, 40, 44, 45, 53, 55
tiara, Trochus, 45
tiara, Ziziphinus, 45
tigilense, Ciliatocardium, 311, 313
tigilense, Laevicardium, 311, 313
Timoclea

marica, 331, 332
titthus, Serripes, 320
tohiveana, Partula, 129
tokunagai, Cardium, 306, 307
tokunagai, Clinocardium, 306
tokunagai, Fuscocardium, 306
Tonna

galea, 224

maculosa, 290
torrei, Calliostoma, 31, 54
tortuosa, Trisidos, 78, 79
totteni, Hydrobia, 246
Trachycardiinae, 299
Trachycardium, 298

hanpeizanense, 303

kinsimarae, 303
Transennella, 191
transversa, Anadara, 216, 223, 248
triangularis, Serripes, 317
Trichotropis

borealis, 245
tridentata, Pleuromeris, 224
Trigoniina, 264
trilineata, Pandora, 224
Triodopsis, 144
triseriata, Lunatia, 214, 216, 221, 247
Trisidos, 77-79, 82-84

fajumensis, 78

prototortuosum, 78

tortuosa, 78, 79

yatsuoensis, 78

yongei, 77-78, 83
trisinuata, Thyasira, 222
trispinosa, Seguenzia, 15
Trivia, 260

maltbiana, 224, 291
trivittatus, Nassarius, 215, 216, 222
trivolvis, Helisoma, 97, 98
Trochacea, 4, 260
Trochidae, 1-62, 111
Trochina, 4
Trochoidea, 261
Trochus, 9, 17

aeglees, 7

amabilis, 42

clavatus, 1, 20

conula, 25

conulus, 25, 26

coronata, 5

euspira, 5

helicinus, 4

jujubinus, 28

lima, 9, 13

MALACOLOGIA

lunatus, 28

moniliferus, 15

ottoi, 7, 9

peregrinus, 9

perspectivus, 28

pulcher, 26

quadricarinatus, 17

rhina, 13

rhysus, 21

tampaensis, 28

tiara, 45

zizyphinus, 25
Trophon, 110, 119, 123

clathratus, 123

geversianus, 123

minutus, 110, 119, 120, 123, 124

muricatus, 123

truncatus, 123
tropicus, Bulinus, 154
truncata, Barnea, 223
truncata, Mya, 238, 246
truncatus, Bulinus, 147, 153
truncatus, Trophon, 123
trunculata, Lymnaea, 96
Tryblidiacea, 254
Tryblidiida, 253-255, 267, 269, 270, 273, 278
Tryblidiina, 254, 255
tuberculata, Nodilittorina, 291
tubula, Solariella, 39, 41, 53, 55
tubulata, Solariella, 23
tubulatus, Echinogurges, 22, 23, 53, 55
tulipa, Fasciolaria, 290, 294
tumidum, Gafrarium, 331
tumidus, Polinices, 329, 330, 332
Turbinella

angulata, 291, 292
turbinoides, “Solarium,” 9
Turbo

canaliculatus, 291
Turbonilla

elegantula, 222

interrupta, 222

polita, 221

reticulata, 223
Turcicula, 2, 15, 17

imperialis, 2, 15, 16
turricula, Propebela, 245
Turritella

exoleta, 223
Turtonia

minuta, 246
uchidai, Cardium, 307
uchidai, Clinocardium, 307, 310
uchidai, Keenocardium, 307
ulocyma, Chione, 184, 185
Umboniinae, 4, 23
Umbonium, 5, 7

bairdi, 5, 7

euspira, 5
unciangulare, Cardium, 320
unciangulare, Serripes, 320
undata, Astarte, 216, 221, 225, 237, 238, 247
undata, Velutina, 245

INDEX, VOL. 19 355

undatella, Chione, 157-199 vestita, Amicula, 233
undatum, Buccinum, 213, 215, 216, 221, 234, 236. "Vetigastropoda, *261, 270
247 vetula, Microgaza, 1, 46, 48, 49, 53, 55

unifasciata, Pyramidella, 223
Unionina, 264
Urosalpinx

cinerea, 236
utcholokensis, Papyridea, 315, 316
utcholokensis, Profulvia, 315, 316
uvutschensis, Serripes, 317, 320
uyemurai, Cardium, 311, 313
uyemurai, Cerastoderma, 311, 313
uyemurai, Ciliatocardium, 311, 313
vaillanti, Calliotropis, 8, 9
Valvatacea, 261
Valvatella, 4
Vampyromorpha, 271
Varicorbula

operculata, 224
Vasticardium

arenicoloides, 303

shimotokuraense, 303
Vasum

muricatum, 291
vaughani, Antillachelus, 35
veliei, Calliostoma, 26
veliei, Hyalina, 223
Velutina, 260

plicatilis, 245

undata, 245

velutina, 245
velutina, Velutina, 245
Veneracea, 157
Veneridae, 157-199, 303, 329, 331
Venerina, 264
Venerinae, 192, 193
Veneroida, 82
Venerupis, 185, 193, 194

pullastra, 191
ventricosus, Colus, 247
Ventroplicida, 252
Ventropoda, 267
Venus, 189

rudis, 191

Striatula, 185

verrucosa, 187
Vepricardium, 298
Veronicellacea, 262
verrilli, Diplodonta, 224
verrucosa, Venus, 187
versicolor, Nerita, 291
versicolor, Tellina, 216, 224
Verticordiacea, 263
Verticordiidae, 263

Vexillum
dermestinum, 291
vibex, Nassarius, 216, 223, 248, 291
vincta, Lacuna, 240, 245
virginea, Acmaea, 238
virginica, Crassostrea, 222, 236, 238
Vitrinella, 225
vittatus, Donax, 329
Viviparus, 107
Volborthella, 271
Volutomitra
groenlandica, 245
vulgaris, Loligo, 286
vulva, Cardium, 310
Wallucina, 330-332
watsoni, Callogaza, 24, 25
watsoni, Gaza, 25, 53, 55
willcoxi, Aplysia, 222
Xylophaga
atlantica, 221, 247
Yagudinella, 301-303, 320
makiyamai, 321
nigamiensis, 321
nomurai, 321
notabilis, 301, 321, 322
yokoyamai, 320, 322
yakatagense, Cardium, 310, 313
yakatagense, Cerastoderma, 310, 313
yakatagense, Ciliatocardium, 310, 313
yamasakii, Cardium, 311, 313
yamasakii, Cerastoderma, 311, 313
yamasakii, Ciliatocardium, 311, 313
yatsuoensis, Trisidos, 78
yokoyamai, Serripes, 322
yokoyamai, Yagudinella, 320, 322
Yoldia
amygdales, 246
limatula, 221, 234, 238, 247
myalis, 233, 234, 246
sapotilla, 213, 215, 221, 246
yongei, Trisidos, 77-80, 83

yucatecanum, Calliostoma, 27, 29, 53, 55

yucatecanum, Eutrochus, 27
yucatecanum, Leiotrochus, 27
ziczac, Littorina, 291
Zirfaea

crispata, 221, 234, 239, 247
Ziziphinus, 25

jujubinus, 28

tiara, 45
zizyphinus, Trochus, 25

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Vol. 19, No. 2 MALACOLOGIA

CONTENTS
R. T. DILLON, Jr.
Multivariate analysis of desert snail distribution in an Arizona canyon
D. R. FRANZ and A. S. MERRILL

Molluscan distribution patterns on the continental shelf of the Middle
Atlantic Bight (northwest Atlantic)

D. В. FRANZ and A. $. MERRILL

The origins and determinants of distribution of molluscan faunal groups
on the shallow continental shelf of the northwest Atlantic

L. v. SALVINI-PLAWEN

A reconsideration of systematics in the Mollusca (phylogeny and higher
classification)

D. A. MCCONATHY, R. T. HANLON and R. F. HIXON

Chromatophore arrangements of hatchling loliginid squids

(Gephakıpoda.Myopsida) :. ¿[oido das nek Lens ae Je ee $

A. R. PALMER
Locomotion rates and shell form in the Gastropoda: a re-evaluation
A. I. KAFANOV

Systematics of the subfamily Clinocardiinae Kafanov, 1975 (Bivalvia,
Cardiidae)

G. J. VERMEIJ

Drilling predation of bivalves in Guam: some paleoecological implications ake

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