Taxonomy and distribution of Siphonodentaliidae Mollusca in Eastern Pacific waters

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TAXONOMY AND DISTRIBUTION OF SIPHONODENTALIIDAE:

MOLLUSCA

IN EASTERN PACIFIC WATERS

A Thesis Presented to the Faculty of the Department of Zoology The University of Southern California

In Partial Fulfillment of the Requirements for the Degree Master of Science

by William K. Emerson August 1950

UMI Number: EP67192

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This thesis, w ritten by

William.

Emfixsan.

under the guidance of hJi.8... Faculty Committee, and approved by a ll its members, has been presented to and accepted by the Council on Graduate Study and Research in p a rtia l f u lfill­ ment of the requirements fo r the degree of ...............

D^..Auguet..l5iQ.

Faculty Committee

Chairman

ill TABLE OF CONTENTS PAGE INTRODUCTION.........................................

1

MATERIALS AND METHODS..................................

2

HISTORICAL REVIEW.....................................

5

REVIEW OF LITERATURE.................................

7

CHARACTERISTICS OF THE C L A S S ............................ 10 T E R M I N O L O G Y ........................................... l«f SYSTEMATIC TREATMENT .................................

16

DISTRIBUTION SUMMARY.................................... 8**FOSSIL RECORD........................................... 90 GENERAL SUMMARY......................................... 95 P L A T E S ................................................. 98 LITERATURE CITED .....................................

109

1 INTRODUCTION This paper is the result of a taxonomic and distri­ butional study of the scaphopod family Siphonodentaliidae including species occurring on the continental shelf and slope of west America from the Polar Sea to Cape Horn, and the Galapagos Islands*

The species comprising the fauna

within this range are henceforth considered as being Eastern Pacific or West American forms.

The word, family, refers to

Siphonodentaliidae unless otherwise indicated. It is the purpose of this study to bring the nomencla­ ture of family up to date, compile all pertinent taxonomic data, and determine from the available data, the bathymetric and geographic distribution of the species.

An attempt is

also made to outline the phylogeny of the family based on the fossil record and anatomical characters. At this time I would like to express my appreciation to Doctors Irene McCulloch, W. E. Martin, and R. C. Os burn for their interest and assistance.

I am also indebted to

Dr. H. A. Rehder, Curator of the Division of Mollusks, United States National Museum, for the use of the facilities of the Division, including photographs of the type specimens con­ tained in the national collection.

2 MATERIALS AND METHODS The great bulk of the specimens examined for this report is contained in the vast collections of the Division of Mollusks, United States National Museum*

Most of the

specimens comprising this collection were dredged by the steamer ALBATROSS under the auspices of the United States Fish Commission during the course of her various scientific cruises along the coast of the Western Hemisphere.

The work

of the ALBATROSS has been recently described in detail by Hedgpeth (19^5) • The national collection contains the types of over half of the Eastern Pacific species and is invaluable as a reference collection. The large collections of the Allan Hancock Foundation of The University of Southern California, the San Diego Museum of Natural History, and the late George Willett have also been available for study. The extensive material accessible for examination has provided the writer with an unusual opportunity for gaining an insight into the taxonomic problems of the family. An attempt has been made to ascertain the valid geno­ type of every generic and subgeneric unit included in the paper.

In fixing the types of the genera, every effort has

been made to rigidly follow the International Rules of Zoological Nomenclature.

However, it is obviously impossible

to search through all the enormous amount of molluskan

literature in order to determine the earliest designated type for the groups lacking original designations*

Therefore,

some of the authorities given for subsequently designated types may be erroneous, as earlier valid designations might have been overlooked#

In order to prevent any misunderstand­

ing regarding the selection of the types, and thus the generic concepts, the reason governing the type selection is given where possible* The outline for each species comprises eight parts which are listed in the following order:

synonymy, original

description and supplementary description if needed, remarks, geographical range, fossil records if any, records of Recent species, depth range and average, type locality, and type depository. The synonymy contains all pertinent references to the species concerned*

Citations which do not include figures or

have not had the hypotypes personally examined are assumed to be correctly identified.

The locality data, if not too exten­

sive, are given in each reference in order to indicate whether the record is new or a repetition of an earlier one. As most of the species were adequately described by the original authors, only a few supplementary descriptions have been added.

The advantage of having the original

descriptions available in one paper need not be emphasized. The remarks, by design, have been reduced to the

If minimum.

This part of the specific treatment is utilized

primarily to compare the species concerned with its closest relatives and describe the state of preservation of the type material. In order to assure the validity of the geographical and depth data, only that of specimens examined are utilized. The fossil occurrence is given for all records thus far reported.

The depository of the Recent records is indicated

for each citation.

The number of specimens contained in each

lot is shown by the number contained in parenthesis at the end of the citation, e,g,, (10), a north-south sequence.

The records are listed in

The geographical data and bathy­

metric data are summarized at the end of the taxonomic sec­ tion. An effort was made to locate the type depository of all the species.

The fact that many of the types are depos­

ited in the United States National Museum, enabled the writer to study them.

It was found necessary to select lectotypes

from the syntypic lots for many of the species.

The Museum

catalogue numbers of the types are given when known. Each species is figured with the exception of one, which is a species dubium. is figured.

Wherever possible a type specimen

5 HISTORICAL REVIEW Throughout the early period of systematics, authors occasionally described various tubiculous gastropod shells as scaphopods.

Calcareous worm tubes of the annelid genus

Dltruna were placed in the Scaphopoda until Berkeley (183^) discovered the vermian character of the tubes*

Paleontolo­

gists, however, up to the turn of the century continued to describe the tubes of the annelid family, Serpulidae, as scaphopods• After the molluskan character of the animals was confirmed, the scaphopods were classed among the Gastropoda, near the genus Fissurella*

Blainville (1819) was the first

to rank them as a distinct order of Gastropoda under the name, Clrrhobrachiata*

After a careful anatomical investiga­

tion, Lacaze-Duthiers (1856-7) created a new class, concha, for the group*

Soleno-

The name, Scaphopoda, \diich was pro­

posed by Bronn (1862), has been more generally used for the sake of uniformity with the other molluskan class names* Lacaze-Duthiers (1856-7) placed the group under the Acephala, maintaining that the two-fold origin of the mantle showed a relationship closer to the pelecypods than the gastropods.

M* Sars (1859) and Bronn (1862) retained them

among the gastropods, largely due to the possession of a radula and a jaw*

For some time thereafter the theory pre­

vailed that the true taxonomic position of the class was

between the gastropods and the pelecypods, and the scaphopods represented the common ancestors of both classes.

Later

Investigations, however, have shown that the Scaphopoda are more closely related to the gastropods them to the pelecypods. It is generally believed that this class, while very primi­ tive, was not the ancestor of the gastropods, nor the pelecypods, but an evolutionary branch which failed to give rise to any other group.

The Scaphopoda are now universally

recognized as one of the five classes of the phylum Mollusca.

7 REVIEW OF LITERATURE Considering the enormous amount of literature pertain­ ing to the mollusks, little has been written concerning the class Scaphopoda* The literature of the group can be divided into two parts:

first, a period of more or less crude and largely

unsystematic attempts to define the species*

This early era

commences with Linne, followed by Chemnitz, Gmelin, and Lamarck; second, the period of more fundamental knowledge of the biological nature of the group, and the exact specific definition as inaugurated by M* Deshayes.

Fortunately, none

of the Eastern Pacific species were described during the first period* The first modern monographic treatment of the class was by Deshayes (1825)*

This contribution established the

systematic study of the group as a science*

While the pre­

vious authors had failed to provide sufficient specific definitions to identify the species*

Deshayes introduced

full and detailed descriptions along with excellent illustra­ tions.

No representatives of the family were included* Lacaze-Duthiers (1856-57) provided the first accurate

and thorough account of the macroscopic anatomy of the soft parts*

This work remains today the chief source of informa­

tion for the general anatomy of the group.

M. Sars (1851) made a tremendous contribution toward the systematics of the class by establishing the existence of major differences in the pedal anatomy of the two families comprising the class. G. B. Sowerby I, (1832), described the first Eastern Pacific representative of the family, Cadulus perpusillus« Whiteaves (1887) described two species of the family from the Vancouver area of British Columbia. Simroth (189^-5) compiled an extensive bibliography covering papers dealing with anatomy and ontogeny of the class• Dali (1889, 1908, 1909) and Pilsbry and Sharp (18971898) have described the majority of the Eastern Pacific forms most of which were dredged by the ALBATROSS.

Only one Recent

western American species, Cadulus austinclarki Emerson (1951)> has been described since Dallfs 1909 paper. Probably the most valuable contribution towards the systematics of the class is the monograph by Pilsbry and Sharp (1897-1898).

In this comprehensive work the authors

carefully redefined all the generic and subgeneric units, grouped the species according to their apparent affinities, contributed many useful keys and Illustrated in detail the types of many species.

This work is a monographic treatment

of the Scaphopoda of the world, and remains today the most complete reference for the class.

9 Henderson (1920) has carefully monographed the Bast American forms.

It is hoped that the present paper will fill

the need of a reference for the Siphonodentaliidae of the Eastern Pacific.

Only two other regional faunal studies of

the class have been undertaken.

Cotton and Godfrey (19*K))

monographed the south Australian forms, and Hirase (1931) the Japanese species. The major scientific voyages have provided important contributions toward the knowledge of the class.

Watson

(1886) worked up the large CHALLENGER collection5 Boissevain (1906) included all the known Indo-Pacific species in her paper on the SIBOGA Expedition collection.

The smaller expedi

tions have also added many species to the literature.

10 CHARACTERISTICS OF THE CLASS The Scaphopoda, one of the five classes of the phylum, Mollusca, represents a small but very distinct class* mately 1200 specific names have been proposed*

Approxi­

Excluding

synonyms and spurious forms, the class probably contains no more than 750 valid species, of which at least *K)0 are fossil species* Scaphopods are small, marine, bilaterally symmetrical mollusks with an external, curved and tapering shell, which is open at each end*

The animal is attached to the shell by

muscles near the posterior end*

The body is shaped to tightly

fit the shell, and the concave side is generally considered as being dorsal* The foot, which can be protruded from the oral aper­ ture, is rather long, pointed, and variously modified in shape distally*

The cephalic region, as in the pelecypods,

is covered by the mantle*

The head is not developed, the

mouth being situated at the base of the foot in a projection of the pharynx, the buccal mass, which contains the oral cavity*

There are no eyes, the mouth being surrounded by

four to eight oral lobes which have scalloped or smooth mar­ gins.

At the base of the snout, there arise two tassels of

long filamentous contractile tentacles, which hang down into the mantle cavity and can be projected far beyond the oral aperture*

The end of these tentacles, or captacula, is

11 swollen Into the shape of a spoon and can become attached to foreign objects by suction.

These tentacles are easily

detached or broken off, and in such cases are regenerated. Apparently the tentacles are used as organs of touch and for seizing particles of food, such as foraminifera, minute bivalves, etc. The mouth opens into a V-shaped intestine, in the anterior portion of which is the pharynx, containing the jaw and the radula. present.

The heart is rudimentary, no auricles being

There is no special respiratory apparatus as

exchanges of gases are conducted through the wall of the mantle. The nervous system is well developed with five major ganglia being present.

A pair of nephridia open to the out­

side by two pores near the anus.

The sexes are separate, the

single gonad discharging its products through the right nephridium.^ The scaphopod shell grows by successive additions to the larger or anterior end.

Frequently the shell is shortened

at the small end by breakage, wear, or reabsorption to pro­ vide more space for the anal sac.

There is no operculum.

The exterior of the tube is smooth, longitudinally striated, or annulated.

Some species have the apical orifice crenulated

1 For the anatomical details see Plate 5*

12 or fissured. The scaphopod shell is composed of aragonite arranged in three distinct layers.

Bjrfggild (1930) has shown the two

outer layers to be constructed of homogeneous or finely prismatic crystals, and the larger middle layer composed of crossed lamellae concentrically arranged.

The lamellae are

similar in appearance to those found in the pelecypods. Shells rarely attain a length of six inches, although a few species living in the Permian reached twelve inches in length.

No Recent species of the Siphonodentaliidae thus far

described measures more than twenty-five millimeters in length. The scaphopod shell differs from the shells of most gastropods and all cephalopods in having both ends open and being unchambered, and from the calcareous worm tubes of annelids in the presence of three layers Instead of two. The scaphopods resemble the gastropods in their univalve shell, and in the possession of a radula; the pointed foot, the non-lobed velum in the veliger, the reproductive system, the bilateral symmetry of the organs generally, and the absence of any head, eyes, or cephalic tentacles are characters which approximate them to the pelecypods. The animals live buried at an angle of

degrees or

less with the surface of the benthos, the posterior end pro­ jecting.

Water is circulated in and out of the exposed

13 apical orifice.

The oral tentacles remove foraminifera,

minute bivalves, ostracods, detritus, etc. from the mud or sand. Their principal enemies appear to be molluskan; many shells have been found in the stomachs of several species of Opisthobranchs, and others are killed by the boring of rapa­ cious gastropods. large numbers.

Henderson (1920) asserts fish consume

MacGlnitie (19*19) reports finding the ovaries

of the vest American Dentalildae, Dentalium neohexagonum Pilsbry and Sharp, filled with trematode larvae of an unknown species. Many sessile invertebrate become attached to the outer surface of the shells.

Several species of calcareous algae

are commonly found encrusting both living and dead specimens. Many of the Eastern Pacific Dentalildae have shells which are large enough to accommodate hermit crabs.

These pagurids

have become adapted to the shape and curvature of the shells. Pvlopaeurus holmes^ Schmitt and Orthopagrus minimus (Holmes) occur in the dead shells of several of the larger west American Dentalildae.

lb TERMINOLOGY Taxonomic terms The Tew terms used In the description of the species are In most cases self-explanatory.

The descriptive nomen­

clature utilized in the remarks has been standardized in an effort to eliminate confusion which might arise from the use of synonyms. Since many authors have used obscure or obsolete terminology, a brief discussion of the morphologic features used in classification of the family follows.

The shell,

being open at both ends, is sometimes referred to as a “tube." The majority of the Siphonodentaliidae possess a shell with the greatest diameter or hemisphere near the middle of the tube.

The shell tapers from the region of greatest diameter

toward each end, the attenuation being greater at one end. The large end contains the oral or anterior aperture, which is usually termed the APERTURE.

The smaller or posterior end

possesses the apical or anal aperture; the term, APICAL ORIFICE is preferred. the apex.

The posterior tip is naturally called

The slits or notches if present occur at the apex.

The concave side represents the dorsal aspect.

Since

some of the earlier writers considered the convex side dorsal, the terms concave and convex are preferred.

The right and

left aspects of the shell are called the lateral faces.

15 Abbreviations for Institutions AHF:

Allan Hancock Foundation, The University of Southern California (Los Angeles).

ANSP:

Academy of Natural Sciences of Philadelphia.

CAS:

California Academy of Sciences (San Francisco) •

MCZ:

Museum of Comparative Zoology at Harvard College (Cambridge, Mass.).

SDSNH:

San Diego Society of Natural History.

USNM:

United States National Museum (Washington, D. C.)»

16 SYSTEMATIC TREATMENT Classification of the SCAPHOPODA The class Scaphopoda includes the families Dentalildae and Siphonodentaliidae.

The two families are distinguished

from each other by differences in the median tooth of the radula, the form of the foot, and certain shell characters. Key to the Families of Scaphopoda I.

Width of central tooth of radula double its height; Foot with an encircling epipodial sheath which is discontinuous, being slit on one side; Shell with greatest diameter at the oral aperture, surface sculptured or smooth------------------- DENTAL IIDAE

II.

Width of central tooth of radula much less than double its height; Foot without an epipodial sheath, a slender vermiform organ or expanded distally into a symmetrical disk usually with a crenate periphery and often with a central process or filament; Shell generally contracted toward the oral aper­ ture, surface without sculpture except in two restricted groups

— --- -— -SIPHONODENTALIIDAE

Key to the Genera of SIPHONODENTALIIDAE I.

Shell with greatest diameter at oral aperture,

17 tapering to apex* A.

Shell longitudinally ribbed, angular in cross section near the apex ---------

-Entallna

A* * Shell smooth, circular or sub­ oval in cross section through­ out----------------------I.

1

Apical apex of shell cut into lobes or teeth; pedal disk of animal without a central f1lament------- — S inhonod enta

I I. Apical apex of shell simple, unslit; pedal disk of animal with a long central fila­ ment--------------------- Pulsellum II*

Shell with greatest diameter not at the aperture, inflated more or less near the middle or anteriorly, con­ tracting toward the aperture as well as tapering posteriorly; pedal disk of animal without a central filament— — —

— —

---- —

----— Cadulus

18 Family SIPHONODENTALIIDAE Genus Entalina Montersato, 1872 1872 Entalina Monterosato, Notizie intorno alle Conch. Fissile di Monte Pellegrino e Ficarazzi, p. 27• 1897 Entalina Sacco, I Moll. Terreni Terrziarii de Piedmonte e Della Liguria, Labraio Ra Acad, delle Sci., vol. 22, p. ll*f. 1897 Entalina Pilsbry & Sharp, Man. Conch., vol. 7* P« 131* 1920 Entalina Henderson. USNM Bull. Ill, p. 131. Genotype (by subsequent designation, Sacco, 188^) Dentalium tetragonum Broochi, 1811*, (-Entalina quinquangulan^ (Forbes), l8**3); Miocene, Northern Italy and Vienna Basin. Diagnosis:

Shell as in Dentalium in having the greatest

diameter at the aperture, strongly curved, rather small; sur­ face sculptured with many longitudinal riblets; apex angular or rounded in section; foot of animal expanded distally into a disk with a digitate periphery and a median process or fila­ ment, plate 5, figures **, 5* Remarks:

The angular apex, lack of apertural constric­

tion, and sculptural features suggest affinity with Dentalium. However, the anatomical features are extremely similar to those of Pulsellum.

While the members of Entalina possess

19 many of the shell features which are characteristic of the family Dentaliidae, the structure of the foot serves to place

it in the family Siphonodentaliidae.

It differs from all

other groups of the family in the possession of an angular shell, and with the exception of Strlocadulus in having longi­ tudinal sculpture*

The longitudinal rlblets, plate 2,

figure 2, are much more prominently developed in Entalina than in Strlocadulus. plate

figures 1 and 2*

of the genus live in moderately deep water*

Most species

The lack of

intensive water dredging off the west coast possibly accounts for the apparent absence of species from the Eastern Pacific waters. This group may represent the link between the Dentaliidae and Siphonodentaliidae*

The members of the genus

first appear in the geological record at the base of the Cenomanien, middle Cretaceous*

The group has undergone little

change since its first appearance* Genus Pulsellum Stoliczka, 1868 1868 Pulsellum Stoliczka, Mem. Geol. Surv. India, vol. 2, p. Mfl. 1878 Sinhonentalis G. 0* Sars, Bidrag Til Kundskaben om Norges Arktiske Fauna, p* 1(A-, genotype, here designated: Pulsellum lofotense M. Sars, 1865. 1888 Pulsellum Cossmann, Ann* de la Soc* Royale Malcalog. de

20 Belgique, vol. 23, p. I?. 1896 Siphonodentalls [sic], Clessin, Syst• Conchyl-Cab., vol. 6, no. 11, p. 30, [error for Sjphonentalis]. 1897 Pulsellum Pilsbry & Sharp, Man. Conch., vol. 17, p* 138. 1920 Pulsellum Henderson, USNM Bull. Ill, p. 92. Genotype (by subsequent designation Cossmann, 1888) Pulsellum lofotense M. Sars, 1865; Recent, North Eastern Atlantic, Mediterranean and Aegean Seas; Pliocene of Calabria and Sicily. Diagnosis:

Shell moderately to strongly curved,

slightly tapering, largest at the oral aperture, typically circular in section, rarely compressed dorso-ventrally; sur­ face smooth, without sculpture other than growth lines; apex simple, without lobes or slits; foot of animal with a pedal disk as in Siphonodentaliumf but pedal disk convex, not con­ cave, and provided with a central filament. Remarks:

The members of this genus have shells which

are similar to those of Siphonodentalium. but lack the apical lobes and slits.

The development of a long medial filament

on the pedal disk is the major character separating the two genera*

While Pulsellum has been considered a subgenus of

Siphonodentalium by many authors, it seems best to consider Pulsellum of generic standing due to the distinct anatomical

21 differences between the two groups. The geologic and geographic ranges of the genus are similar to those of Siphonodentalium.

The first species

appears in the Miocene as is the case with Siphonodentalium. Stoliczka (1868) proposed Pulsellum for the three Hecent species described by M. Sars in 1865 as Siphonodentalium lofotensey affine. and pentagonumT which were found by Stoliczka to differ from true Siphonodentalium by having a simple apical orifice and a greatly modified foot.

Cossmann (1888) selected

Pulsellum lofotense (M. Sars), 1865, as genotype.

Siphono­

dentalium pentagonum M. Sars, 1865, is a synonym of Entalina auinauangularls (Forbes), 18**3, and belongs in the genus Entalina. G. 0. Sars (1878) established Sjphonentalis for Siphono­ dentalium M. Sars, 1865, S. affins M. Sars, and S. tetragonum (Brocchi), l8l*f.

He removed these species from Siphonoden-

as conceived by M. Sars in 1859 because of the presence of a simple apical orifice and the development of a convex pedal disk with a medial filament.

Pulsellum lofot ense

(M. Sars), 1865, is designated above the genotype of Siphonentalis.

Sjphonentalis thus becomes a synonym of Pulsellum.

Siphonodentalium teragonum (Brocchi), lSlM*, a longitudinally striated species, has been removed from this group and placed in the genus Entalina.

22 Pulsellum aberrans Whit eaves, 1887 plate 1 , figure 6 1887 Cadulus aberrans Whiteaves, Trans* Roy* Soc* Canada, vol* b, sec. b, p. 12^, fig. 2, (Quatsino Sound, British Columbia). 1898 Cadulus (Gadila) aberransT Pilsbry & Sharp, Man Conch., vol. 17, p. 193* pl* 35* fig* 16, (copy of original figure)• 1921 Cadulus aberrans, Dali, USKM Bull. 112, p. 58, (Quatsino Sound, B. C.). 1927 Cadulus aberrans T Oldroyd, Stanford Univ. Publ. Geol. Sci., vol. 2, pt. 1, p. 16, (Quatsino Sound, B. C.). 1937 Cadulus aberrans, Keen, Check List, p. 32, (5l°N, Quatsino Sound, B. C.). 19^5 Cadulus aberrans. Burch, Min. Conch. Club So. Calif., no. 1+6, p. 15, (Quatsino Sound, B. C., to San Clemente Id., Calif.). Original descriptions f,Shell slender, moderately but distinctly curved, large and much elongated for the genus, increasing very slowly but regularly in diameter, not distinctly (if at all) swollen in advance of the middle, and very slightly and scarcely perceptibly constricted immedi­ ately behind the aperture. Test extremely thin, sur­ face polished, very glossy and shining, smooth to the naked eye. but under a lens it is seen to be marked with minute and transverse but somewhat oblique growth lines. Length of an average, full-sized example, 13*5 mm.5 greatest breath of the same near the anterior end, 1.3 mm.**, Whiteaves, 1887.

23 Supplementary description:

Shell is long, narrow,

moderately curved in the posterior portion, considerably attenuated posteriorly. stained yellow-brown.

Surface is dull, bluish-white, often Some specimens have surface areas

which are eroded exposing the chalky middle layer.

Aperture

is nearly circular in outline, not constricted, generally oblique; apex is simple, not slit.

Section of tube is very

slightly dorso-ventrally compressed. Remarks:

The exact identity of this species has

remained in doubt since the original publication.

While I

have not examined any of the type material, the species appears from the inadequate description and poor figure to be a shallow water form which is especially common in the Puget Sound— south Alaska area.

This northern form, which

also ranges in deeper water south to California, has no noticeable apertural constriction.

This character together

with the possession of a simple apex suggests generic assign­ ment to Pulsellum. Unfortunately, the specimen figured, plate 1, figure 6 , is not very representative of the species.

A portion of the

apertural rim has been lost, giving it a much stouter outline than normal.

Range:

Forester Id., Alaska, 56°N, (Willett coll.),

to Santa Cruz Id., Calif.,

(AHF coll.).

Records: Forrester Id., Alaska, Willett coll., (10). Craig, Alaska, Willett coll., (12). Ketchikan, Alaska, Willett coll., (17)* 3.6 mils, off E. Pt. Santa Rosa Id., 33°5VN, 55 fms., AHF bottom sample 1230, (15)* 1 mi. S. of Pt. Bennett, San Miguel Id., Calif., *+3 fms. AHF bottom sample 1238, (7). Prisoners Harbor, Santa Cruz Id., Calif., 3^°02*N, 35h-5 fms., AHF 996-39, (5)* 1 1/2 mils. N. W. of Cavern Pt., Santa Cruz Id., Calif., 3^°0>+,N, 5^-56 fms., AHF 1300->tl, (5). (common in Puget Sound in 2 -20 fms.). Depth range:

35-55 fms., av. *+8 fms.

Type locality:

Forward Inlet, Quatsino Sound, N. W. of

Vancouver Id., British Columbia, in 10-20 fms., (“very abundant11)• Type depository:

Types in Ottawa Museum, fide I. S.

Oldroyd, 1927* Genus Siphonodentalium Sars, 1859

1859 Siphonodentalium M. Sars, Videnskabs- Selskabet i Christiania, Aar, p. 52. 1888 Siphonodentum Locard, Prodr. Mai. Fr., Ann Soc. d ’Agricult Lyon, p. 1**9, [footnote], emendation for Siphonodeptal^unj

25 Sars. 1888 Tubidentalium Locard, Ibid., p. 1**9, [footnote], new name for Siphonodentalium Sars. 1897 Siphonodentalium Pilsbry & Sharp, Man. Conch., vol. 17, P. 135*

1920 Siphonodentalium Henderson, USHM Bull. Ill, p. 88. Genotype (by monotypy) Siphonodentalium vitrum Sars, 1851, not Gmelin, 1798, = Sjphonodentalium lobatum Sowerby, i860 Diagnosis;

Shell moderately to strongly curved,

slightly tapering, largest at the aperture, typically circu­ lar in section, rarely compressed dorso-ventrally; surface smooth, without sculpture other than growth lines; apex large cut into lobes; foot of animal provided with a pedal disk, disk concave medially, lacking a central filament or process, plate 5, figure 2 , 3 * Remarks:

This small group does not appear in the

fossil record until the Eocene.

The few Recent species thus

far described are widely distributed and confined to deep water except in high latitudes.

Only one species has been

reported from the Eastern Pacific waters. Locard (1888) emended the name of the genus to Sinhonodontum and suggested that the name Tubident^i,j,um would be more appropriate for the group.

These name changes have no

standing other than being an emendation and a junior synonym respectively. Sjphonodent alium auadrifissatus Pilsbry & Sharp, 1898 plate 1 , figure 3 * 1898 Cadulus (Polvschides) auadrifissatus “Carpenter** Pilsbry & Sharp, Man. Conch., vol. 17, p. 1?0, pi. 29, figs. 1013, (San Diego, and San Pedro, Calif.). 1921 ?Slphonodentalium auadrifissatumT Dali, USNM Bull. 112, p. 58, (Monterey, Calif., to SanDiego, Calif.). 1927 Siphonodentalium auadrifis satum f Oldroyd, Stanford Univ. Publ. Geol. Sci., vol. 2, pt. 1, p. I1*,

(San Diego to

San Pedro, Calif.). 1937 Siphonodentalium auadrifis sat um T Keen, Check List, p. *+6 , (21-37s29*, Monterey, Calif., to ?Maria Madre Id., Mexico)• Cadulus auadrifissatus. Burch, Min. Conch. Club So. Calif., no. **6 , p. I1*, (off Redondo Beach, Calif., to Ensenada, Lower Calif., in 7-30 fms.). Original description: “Shell arcuate, the bend greater posteriorly, slender, but slightly tapering, not swollen, sub­ transparent bluish, with a milky band near the larger end; smooth and rather glossy, the growth lines hardly visible; posterior third slowly taper­ ing, the tube then nearly cylindrical almost to the aperture; quite near the latter it is contracted, the contraction greatest on the convex side.

27 Greatest diameter contained about 7 times in the length of the shell* Aperture oblique, trans­ versely oval; apex cut into four conic teeth by the same number of short slits; the tooth on convex side slightly longest, the other three sub­ equal in length, that on concave side wider and obtuse; edges of the teeth somewhat bevelled distally. Length 8*6 mill*, diam. at aperture 0*85 x 1 .0 , at largest 1.12 x 1.22, at apex 0.6? x 0.7 mill.11 Pilsbry & Sharp, 1898. Remarks:

This species is very similar to the Western

Atlantic representative, Siphonodentalium auadridentalium Dali, but has the aperture less oblique, the apical slits shorter, and the teeth, more prominently bevelled.

Were it

not for the geographical separation, differentiation would be extremely difficult.

There may be but one wide ranging species

in the Western Atlantic and Eastern Pacific waters.

More

material should be available for study before any definite conclusion can be reached.

The Western Pacific form is

common in shallow water along the Southern California coast. There has been a difference of opinion regarding the generic placement of the species.

Some authors have contended

that the species belongs in the genus Cadulus t subgenus Polvschidest due to the possession of deep apical slits.

How­

ever, the complete lack of apertural constriction and the quadrate lobbed apical orifice strongly suggests placement in the genus Siphonodentalium.

The teeth are generally distally

bevelled with the inner shell layer forming the thin outer edge.

This condition never occurs in Polys.chid.es.

Dallfs

28 (1921) assignment to genus Slbhonodentallum Is followed here. P. P. Carpenter gave the species a manuscript name, Sltfaonodantai -tum i*-fissatum. but did not validly describe it. The species should be credited to Pilsbry & Sharp (1898). Ranges

Monterey, Calif., 37°N, (Dali, 1921), to

Fraile Bay, Mexico, Gulf of Mexico, 23°23' N, (USKM Coll.). Records s All USKM San Pedro, Calif., Cooper, (1), type. Off Santa Rosa Id., Calif.,

22' N, b8 fms., USFC

2901, (25). Off Santa Rosa Id., Calif., 3^°06' N, 53 fms., USFC

2902,

(8).

Off La Jolla, Calif., 32°N, 110-199 fms., USFC 1*322,

(5) • Off Pt. Loma, Calif., 32°N, 25 fms., USFC 1*3Olf, (1).

Off San Diego, Calif., 32°26*N, 20 fms., USFC 2932, 0*). Off S. Coronado Id., Mexico, 3**°, 55-155 fms., USFC

(6). Salinas Bay, Carmen Is., Gulf of Calif., Mexico, 2-1* fms., Hawkins, (1). S. end Angel de la Guardia Id., Gulf of Calif., Mexico, Bartsch, (1). N. side of Fraile Bay, 23°23’ N, 10-30 ft., Hawkins,

(6).

Gulf of Calif., Mexico, 31°37' N, USFC 3020, (2). Depth range 2-199 fms., av. 385 common in 10-20 fms. off Southern California. Type locality:

San Pedro, Calif.

Type depository: Lectotype: Paratype:

USHM 19**62, here selected, (Cooper)* Phila. Acad. Sci., (Hemphill).

Genus Cadulus Philippi, l8¥f 18M+ Cadulus Philippi, Enumeratio Moll. Sicilae, vol. 2, p. 209* 1897 Cadulus Pilsbry figures 1, 2. 1898 Cadulus (Gadila) platystoma Pilsbry & Sharp, Man. Conch., vol. 17, p. 180, pi. 35* [lectotype], (off Manta, Ecuador). 1908 Cadulus (Gadila) platystomar Dali, Bull. MCZ, vol. W3 , no. 6, p. 361, (Manta, Ecuador). 1909 Cadulus platystomar Dali, Proc. USHM, vol. 37> no. 170*f, p. 2^9, (Manta, Ecuador). 1918 Cadulus platystoma. Zetek, Revista Neueva, no. 1 & 2, p. 51. 1 9 ^ Cadulus platystomaf Smith, Panamic Mar. Shells, p. b7, (Manta, Ecuador). Original description: "Shell rather large, much bent; bluish-white, somewhat translucent posteriorly; smooth and glossy, growth-striae being scarcely discernible. Strongly swollen posteriorly, the greatest diameter contained about if.** times in the length of the shell; equator between the anterior third and fourth of the shell’s length, the tube rapidly tapering posteriorly, less rapidly anteriorly, where it is decidedly depressed or flattened on the convex face, the flatten­ ing increasing toward the aperture, just behind which there is a slight concavity on the middle of the con­ vex side (fig. 18). Outline of convex side decidedly more arcuate toward the aperture; concave outline modified and slightly convex in the region of the inflation. Posterior end attenuated. Tube compressed between the concave and convex sides at and anterior to the inflation, subcircular in section at the apex. Aperture irregularly elliptical, much flattened along

61 the convex side, the peristome thin, jagged from fracture. Anal orifice sub-circular, with simple edge. Length 12.75 diam. at aperture, 1.3 x 2.0, at greatest inflation 2.52 x 2.92, at apex 0.8 x 0.8 mill, (the antero-posterior dimensions pre­ ceding) ,M [lectotype], Pilsbry & Sharp, l89o. Remarks:

No specimens representing this species have

been found since the original lot of two was collected by the ALBATROSS during the cruise of 1891*

It resembles Cadulus

proculum Dali from the Caribbean, in being rather arcuate and having the tube compressed anteriorly, but is a stouter species which is less attenuated posteriorly and not angulate. C. peruvianus Dali is shorter, more inflated, and less atten­ uated anteriorly. The lectotype, plate 1, figure 1, has a portion of the aperture broken out; the apical orifice also appears to be incomplete.

The paratype, plate 1, figure 2, is more inflated

than the lectotype and has a very oblique aperture, which is not damaged. The subgeneric placement of this species is made uncer­ tain due to the incomplete apertures.

It is allotted tenta­

tively to Platyschides because of its general similarity to the subgenotype. Range: Records:

Known only from type locality. Known only from type locality.

Type locality:

Off Manta, Ecuador, 1°S, in **01 fms.,

62 USFC 2792. Type depository: Lectotype: Paratype:

USNM107699, here selected, USFC 2792. USNM 87567, USFC 2792, (1).

Cadulus (Platyschides) peruvianus Dali, 1908 plate 3, figures 3,

5*

1908 Cadulus (Gadila) peruvianus Dali, Bull. MCZ, vol. ^3, no. 6, p. 361, (off Point Aguaja, Peru). Original description: “Shell milk-white, smooth, polished, arcuate, inflated; aperture oblique, the form oval, with the dorsoventral diameter shorter; equator nearly at the anterior third, the anterior part contract­ ing markedly from the equator forward but without angularity; posterior portion not greatly atten­ uated, rather unusually large for the genus, the anal aperture apparently circular and simple. Length, 12.3; anal end to equator, 8.3; perpendicu­ lar between shell and chord* 1.0; max. diam., 3*0; of oral aperture, 2.0; vertical of do., 1.6; anal aperture, 1.0 mm,11 Dali, 1908. Remarks:

This is a short inflated species in which

the oral aperture is rather oblique.

C. platystoma P. & S.

is a longer, narrower, more attenuated species which has the oral aperture even more obliquely angled.

The paratype,

plate 3, figure *f, is slightly less inflated than the lectotyp©, plate 3 , figure 3* None of the specimens have complete apertures.

The

63 lectotype, plate 3, figure l, possess slight sub-lateral depressions which may be the remnants of shallow notches*

As

in the case for Cadulus platystoma P* & S. , this species is provisionally placed in the subgenus Platyschides* For reasons unknown to me, Dali (1909) did not include this species in his w. . . Collection of shells from Peru.

...*• Ranges

Near Galapagos Ids., 0°21flS, to off Aguja

Point, Peru, 5° 56'S* Records:

Near Galapagos Ids., 812 fms., USFC 2807,

USNM, (1). Off Aguja Point, Peru, 1036 fms., USFC lf65J+, USNM, (2) , types* Depth range:

812-1036 fms., av. 92b fms*

Type locality:

Off Aguja Point, Peru, in 1036 fms*,

USFC h6$b. Type depository: Lectotype:

USNM 602250, here selected, USFC b6$b.

Paratypes:

USNM 122806, USFC b6$b, (1).

Subgenus Dlschides Jeffreys, 1867 l86*f Gadus “Rang” Deshayes, Descript* Anim. sans Vert. Paris Bassin, vol. 2, p. 217, [not Rang, 1829, not Linne, 1758].

6b 1867 Pis chides Jeffreys, Ann* & Mag* Nat* Hist*, (3), vol* 20, p* 251, [contained in text, without a heading]* 3-897 Pis chides Pilsbry & Sharp, Man* Conch*, vol* 17, p* 1^3 • 1897 Plcides Sacco, Moll* Terreni Terrziarii de Piedmonte e Pella Liguria, Labraio dell Ra Acad*, delle Sci*, vol* 22, p* 115, emendation for Pischides Jeffreys* Subgenotype (by monotypy) Pentalium bifissum S. Wood, 18^3, - Cadulus politus S. Wood, 18**2; Recent, Mediterranean, Eastern Atlantic; Pliocene of England and Italy* Piagnosis:

Shell slender, only slightly inflated,

greatest diameter near the oral aperture, constricted at aperture; apex cut into convex and concave lobes by two deep lateral slits, one on each side* Remarks:

The Recent members of this small group occur

in the Atlantic and Pacific oceans*

Fossil species have been

reported from the Paris Basin Eocene and the Pliocene of Europe*

No species have been described from the Eastern

Pacific waters* Beshayes (186*+) incorrectly assigned three fossil species from the Paris Basin to the pteropod genus, Gadus, of Rang (1829)*

Gadus of Linne (1758), a fish genus, is the

first valid use of the name*

Subgenus Polvschides Pilsbry & Sharp, 1898 1898 Polys chides Pilsbry PP* l - W , pis. 1-11. Cooke, A. H.

1895*

Molluscs, Cambridge Natural History Series, vol. 3, pp* 1-^8. Macmillan, London.

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Cotton, B. C., and F. K. Godfrey W 1^). The Mollusks of South Australia, pt, 2, pp. 3203*+l, text figs. 3^1-36^. Government Printing Office, Adelaide. Dali, W. H. 1889*

Scientific Results of Explorations by the U. S. Fish Commission Steamer ALBATROSS, Pt. 7> Pre­ liminary Report of the Collection of Mollusca and Brachlopoda Obtained in 1887-88. Proc. U. S. Nat. Mus., vol. 12, no. 773* PP* 219-362, pis. 51b.

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Illustrations of Unfigured Types of Shells in the Collection of the United States National Museum. Proc. U. S. Nat. Mus., vol. 66, no. 255*+, pp. 1-Mf, pis. 1-36.

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