V

THE

VOYAGE OF H.M.S. CHALLENGER.

ZOOLOGY-VOL. XXIII.

REPORT

ON THE

SCIENTIFIC RESULTS

OF THE

VOYAGE OF H.M.S. CHALLENGER

DURING THE YEARS i 8 7 3-7 6

UNDER THE COMMAND OF

Captain GEORGE S. NARES, R.N., F.R.S.

AND THE LATE

Captain FRANK TOURLE THOMSON, R.N.

PREPARED UNDER THE SUPERINTENDENCE OF

THE LATE

Sir C. WYVILLE THOMSON, Knt., F.R.S., &c.

KEG1US PROFESSOR OF NATURAL HISTORY IN THE UNIVERSITY OF EDINBURGH DIRECTOR OF THE CIVILIAN SCIENTIFIC STAFF ON BOARD

AND NOW OF

JOHN MURRAY

ONE OF THE NATURALISTS OF THE EXPEDITION

Zoology — Vol. XXIII.

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CONTENTS.

I. — Report on the Rteropoda collected by H.M.S. Challenger during the years 1873-1876. Part II. — The Thecosomata.

By Paul Pelseneer, D.Sc. (Brussels).

( The Manuscript was received 2nd August 1887.)

II. — Report on the Pteropoda collected by H.M.S. Challenger during the years

1873-1876. Part III. — Anatomy.

By Paul Pelseneer, D.Sc. (Brussels).

( The Manuscript was received 5th December 1887.)

HI. — Report on the Hydroida dredged by H.M.S. Challenger during the years 1873-1876. Part II. — The Tubularhsle, Corymorphhsle, Campanularhsle, SERTULARiNiE, and Thalamophora.

By Professor G. J. Allman, M.D., LL.D., F.R.C.S.I., F.R.SS. L. & E., M.R.I.A., C.M.Z.S., Mem. Roy. Danish Acad. Sci., &c.

( The Manuscript ivas received in Instalments between 29 th August 1887

and 9th February 1888.)

XY. Report on the Entozoa collected by H.M.S. Challenger during the years

1873-1876.

By Dr. 0. von Linstow of Gottingen.

( The Manuscript was received 2kth October 1887.)

y Report on the IIeteropoda collected by H.M.S. Challenger during the years

1873-1876.

By Edgar A. Smith, F.Z.S., Assistant in the Zoological Department of

the British Museum.

( The Manuscript was received 21 st January 1888.)

ERRATA IN PART LJV.

Page 107, line 9, for “ globulosa” read “ gibbosa Page 112, line 18, add “Cuvierina columella.”

ERRATUM IN PART LXVI.

Page 2, line 23, for “Opisthobranchiate” read “Tectibranchiate,” and vice versd.

EDITORIAL NOTES.

This Volume contains Parts LXV., LXVI., LXX., LXXI., and LXXII. of the Zoological Series of Reports.

Part LXV. — The First Part of the Report on the Pteropoda, by Dr. Paul Pelseneer, treating of the Gymnosomata, was published in 1887 in Volume XIX., and forms Part LVIII. of the Zoological Series of Reports.

This Second Part of the Report, by the same author, deals with the Thecosomata, and contains 132 pages of letterpress and 2 plates, in addition to woodcuts.

Part LXVI. — In this Third and concluding Part of the Report on the Pteropoda, Dr. Pelseneer treats of the Anatomy of the whole group and discusses the relations of the Pteropoda to the other Mollusca. The Part consists of 97 pages of letterpress and 5 lithographic plates, in addition to other illustrations in the text.

Part LXX. — The First Part of the Report on the Hydroida collected during the Expedition, by Professor S. J. Allman, F.R.S., was published in 1883 in Volume VII., forming Part XX. of the Zoological Series of Reports ; it treated of the Plumularid,® (Plumularinse).

The present Memoir is the Second and concluding Part of Professor Allman’s Report, and treats of the remaining families of the order.

In consequence of the extent and representative character of the collec- tions Professor Allman has been able to give, in addition to the zoological

mu

THE VOYAGE OF H.M.S. CHALLENGER.

descriptions, a very valuable and comprehensive sketch of the morphology and life-history of these animals. This Part consists of 160 pages of letter- press, 39 plates and a map.

Part LXXI. — Had any special attention been paid to collecting Entozoa during the Expedition, a much larger number of species would probably have been obtained than are described in this short but valuable Eeport by Dr. 0. von Linstow of Gottingen, one of the first authorities on this group of animals. The Report consists of 18 pages of letterpress, 2 lithographic plates and a woodcut.

Part LXXII. — In this Report Mr. Edgar A. Smith has brought together systematic lists showing the present state of our knowledge of the Hetero- poda, founded on the collections made during the Expedition. The Report, which consists of 56 pages and 5 woodcuts, will be most useful to future investigators.

John Murray.

Challenger Office, 32 Queen Street, Edinburgh, 9th May 1888.

THE

VOYAGE OP H.M.S. CHALLENGER.

ZOOLOGY.

REPORT on the Pteropoda collected by H.M.S. Challenger during the Years 1873-76. By Paul Pelseneer, D.Sc. (Brussels).

K'a.c/ x\

PART H.-The THECOSOMATA.

INTRODUCTION.

About the end of the year 1885 I was entrusted with the task of making a systematic and descriptive Report on the Gymnosomatous Pteropods and an anatomical one on the entire order, and in the beginning of the present year (1887) the entire Report on the Pteropods was entrusted to me for completion.

The Report is thus divided into three portions as follows : —

1. The systematic survey of the Gymnosomata, which has been already published.1

2. The present Report on the Thecosomata, which along with the former includes the entire systematic survey of the Pteropods collected on the Challenger Expedition.

3. The anatomy of the Thecosomata and Gymnosomata.

As with the Gymnosomata, so in regard to the Thecosomata, I have been forced to make a monographic study of the entire subgroup. But I have not here described all the species actually known, partly because they are on the whole more familiar than the Gymnosomata, and partly because the delay which has been involved in the completion of the entire Report made such a survey impossible. I shall therefore restrict myself to an enumeration of the indubitably genuine species among the entire list of those hitherto described, and to synoptic tables in which these are distinguished from one another.

1 Zool. Chall. Exp., part lviii.

(ZOOL. CHALL. EXP. — PART LXV. — 1887.)

Ttt 1

2

THE VOYAGE OE H.M.S. CHALLENGER.

And as to the species collected on the Challenger Expedition, I shall not describe those which are already sufficiently well known, and in regard to which there is no manner of doubt or dispute. I shall restrict my descriptions to the doubtful or imperfectly known species, attempting at the same time to make their systematic arrangement more lucid and less complex.

It is a noticeable fact that in general works on the systematic relations of Molluscs, the diagnoses of the families and genera of Pteropods are always the same, and that from a comparatively ancient date, just as if they had been verbally copied by successive authors. And since they have not been modified with the progress of research, the result is that they are often incorrect. I have therefore taken particular care with the diagnoses of families and genera, and have based these on specimens which I have myself studied. The diagnoses I have framed as simply and methodically as possible.

My monographic study of the subgroup Thecosomata has been based upon the following collections : —

1. The dry and preserved specimens in the British Museum.

2. The dry shells of Thecosomata in the Brussels Museum.

3. The Thecosomata collected on the “Triton” expedition.

4. The Thecosomata collected by Mr. John Rattray, F.R.S.E., during the cruise of the steamship “ Buccaneer” on the western coast of Tropical Africa (1885-86).

5. The Thecosomata collected by the Italian vessel “Vettor Pisani” during the scientific expedition round the world (1882-85).

6. The Pteropods captured by Surgeon David Bruce, M.B., near Malta (1886).

7. The Thecosomata collected at the Zoological Station at Naples during my stay there (from February to July 1887).

I must also gratefully acknowledge my indebtedness to Mr. Edgar A. Smith, of the Zoological Department of the British Museum, from whom I have received much assistance, to Professor Ch. Yelain, of Paris, and to Mr. W. H. Dali, of the U.S. National Museum.

After enumerating the species I shall discuss the geographical distribution of the group. The phylogenetic relations of the different genera can only be satisfactorily discussed after some treatment of the anatomy, and will therefore be discussed in the anatomical Report.

The Habits of the Thecosomatous Pteropods.

I have nothing to add here either in regard to the history of the group or the differ- ences between the two subdivisions. The subject has been sufficiently discussed in the Introduction to my Report on the Gymnosomatous Pteropods.1

1 Zool. Chall. Exp., part lviii. pp. 1-6.

REPORT ON THE PTEROPODA.

3

So too in regard to the habits of the Thecosomata. Like the Giymnosomata they are pelagic Molluscs, which descend to a certain depth to avoid bright light, and reascend when the light is feeble or absent, and when the sea is calm. They feed mainly on Protozoa (Radiolaria, Foraminifera, Infusoria) or on lower Algae, while the Gymnosomata prey upon decidedly higher animals. This difference of diet is the condition effecting the notable diversity in the structure of the alimentary system, and especially of the buccal and stomachic armature.

The Thecosomata of the Challenger Expedition.

The Thecosomatous Pteropods collected on the Challenger Expedition, which form the material bases of the present Report, comprise two distinct series : —

1. The Thecosomata captured alive in the tow-nets, and preserved in alcohol or in microscopic preparations mounted in Canada balsam or in glycerine. These were entrusted to me towards the end of 1885 for use in my Report on the anatomy of the group.

2. The dry shells from deep-sea deposits, the importance of which will be discussed in the special report on the sea-bottom. This collection was selected from the deposits in the Challenger Office and also by Mr. Alfred E. Craven, who at one time proposed to write the Conchological Report on this group. It passed into my hands in the beginning of 1887, when a large number of the specimens had been already assorted.

I. The Thecosomata taken alive were gathered from seventy stations, and include twenty-eight species representing all the known genera. Among these species there is no new form, though a certain number have been hitherto insufficiently known or only once recorded.

The following table indicates the distribution of these species among the different genera.

Limacina,

Peraclis,

Clio, .

Cuvierina,

Cavolinia,

Cymbulia,

Gleba,

that is, among 7 genera, . . . • • • .28 species.

II. The Thecosomata dredged from the deposits of the deep sea occur in all those known by the title “ Pteropod ooze,” and also in others. I have received the

1

10

1

8

1

1

4

THE VOYAGE OF H.M.S. CHALLENGE R.

shells from the sediments of twenty-one stations most rich in Thecosomata. The results of the study of these shells are detailed in this Report under the title of “ Deposit-shells.” In the different shell-containing sediments which I have examined, I have found twenty-four species of Thecosomata, of which a dozen occur in considerable abundance at many of the stations. One of these forms is quite new. The various forms are distri- buted as follows in the different genera —

Genera.	Species previously known.	New Species.
Limacina, .....	6
Peraclis, .....	1	1
Clio, ......	8
Cuvierina, .....	1
Cavolinia, .....	7	...

Besides these twenty-four species there are five which do not occur in the Challenger collection of preserved Thecosomata. The total number of Pteropoda Thecosomata thus amounts to thirty-three, of which one is new, and a number either insufficiently known or not previously figured.

Limacina, ...... 8

Peraclis, ...... 2

Clio, . . . . . . .12

Cuvierina, ...... 1

Cavolinia, ...... 8

Cymbulia, ...... 1

Gleba, ...... 1

that is, in 7 genera, . . . . . .83 species.

DESCRIPTION OF GENERA AND SPECIES.

PiEROPODA, Cuvier. THECOSOMATA, cle Blainville.

Pterocephala, Wagner, 1885.1 Eupteropoda, Boas, 1886.2

THE GENERA AND FAMILIES OF THECOSOMATA.

In the Systematic Report on the Gymnosomatous Pteropods, I have noted a number of genera formerly included in the group Pteropoda, but which ought long ago to have been relegated elsewhere.

Among the Thecosomata too, a number of forms have been rather recently included which do not belong to the group of Pteropods. Such are, for instance, Cheletropis and Sinusigerci, which are really larvae of Streptoneural Gastropods, whose velum has been mistaken for a fin ;3 and as to Hcdopsyche ( Euribia and Psyche ), it is one of the Gymnosomata, as I have noted in my previous Report.

But even after abstracting the names of genera which ought without hesitation to be removed from the systematic nomenclature of Thecosomata, there remains a long list of titles, which have been invented for living forms realty belonging to the Thecosomata, but of which the majority cannot be retained. Such titles are proportionately more numerous than the generic names established for the Gymnosomata, and this because the generic diagnoses of the Thecosomata have been almost always based upon the shell. To this, which is nothing more than a simple ectodermic secretion, conchologists have attached too much systematic importance. There are indeed certain subgroups of Thecosomata, including a number of generic titles, greater than that of the genuine species.

1 Die Wirbellosen des weissen Meeres, Bd. i. p. 119.

2 Spolia atlantica, p. 179.

3 Gastropods of the family of Csecidae also have long been considered as Thecosomatous Pteropods, under the title Odontidium.

6

THE VOYAGE OF H.M.S. CHALLENGER.

Against such a tendency it is necessary to protest and to revert to a less rigid con- ception of what constitutes a genus, and though one does attach considerable systematic importance to the shell, this must not be exaggerated so as to lead to the erection of a separate genus for species which differ in some minute feature in the shell, but agree with one another in the rest of their characters. In addition to several differences of some importance in regard to the shells, it will be necessary to justify the establishment of a genus by at least one characteristic difference either in the soft structure of the animal, or in certain hard parts like the operculum or the buccal armature, which are generally of real importance in generic and specific diagnoses.

From this it follows that a large number of the generic titles discussed below must either .be abandoned or regarded as synonyms. Some of them again may be considered as designating generic subdivisions, though these are not in any way indispensable in so comparatively small a group as the Thecosomata.

I shall append, from the literature of the group, an alphabetical list of the various generic names given to living Thecosomata : —

Agadina, Gould.

Archonta, Montfort. Balantium , Leach. Campylonaus, Gray. Cavolinia, Abildgaard. Cleodora, Peron and Lesueur. Clio, Linne.

Corolla, Dali.

Creseis, Rang.

Cuvieria, Rang, non Peron. Cuvier ina, Boas.

Cymbulia, Peron and Lesueur. Diacria, Gray.

Embolus, Jeffreys.

Euromus, H. and A. Adams. Gleba, Forsk&l.

Ileliconoides, d’Orbigny. Helicophora, Gray.

Heterofusus, Fleming.

Hyalsea, Lamarck.

Hyalocylis, Fol.

Limacina, Cuvier.

Orbignyia, A. Adams.

Peracle, Forbes.

Pleuropus, Eschscholtz.

Protomedea, 0. G. Costa.

Rheda, Humphreys.

Scsea, Philippi.

Spiratella, de Blainville.

Spirialis, Eydoux and Souleyet. Styliola, Lesueur.

Tiedemannia, delle Chiaje.

Tricla, Oken, non Retzius.

Triptera, Auctorum, non Quoy and Gaimard.

Of these thirty-four titles

I. Two ought to be provisionally set aside as doubtful, for reasons which I shall after- wards submit : —

Agadina, Gould.

Triptera, Quoy. and Gaimard.

EEPOET ON THE PTEEOPODA.

7

II. Twenty-five are duplicates, and ought therefore to be retained simply as synonyms of Thecosomatous genera : —

Archonta, Montfort, . Balantium, Leach, Campylonaus, Gray, . Cleoclora, Peron and Lesueur, . Corolla, Dali,

Creseis, Rang,

Cuvieria, Rang,

Diacria, Gray,

Embolus, Jeffreys,

Euromus, Adams,

LLeliconoides, d’Orbigny, Helicophora, Gray, Heterofusus, Fleming,

Hyalsea, Lamarck,

Hyalocylis, Fol,

Orbignyia, A. Adams, Pleuropus, Eschscholtz, Protomedea, 0. G. Costa, Rheda, Humphreys, .

Scsea, Philippi,

Spiratella, de Blainville, Spirialis, Eydoux and Souley et, Styliola, Lesueur, Tiedemannia, delle Chiaje, Tricla, Oken, .

= Carolina, Abildgaard. = Clio, Linne.

= Peraclis, Forbes.

= Clio, Linne.

= Gleba, Forskal.

= Clio, Linne.

= Curie rina, Boas.

= Cavolinia, Abildgaard. = Limacina, Cuvier.

= Peraclis, Forbes.

= Limacina, Cuvier.

— Limacina, Cuvier.

— Limacina, Cuvier.

= Cavolinia, Abildgaard. = Clio, Linne.

= Cavolinia, Abildgaard. = Cavolinia, Abildgaard. = Limacina, Cuvier.

= Cavolinia, Abildgaard. = Limacina, Cuvier.

— Limacina, Cuvier.

— Limacina, Cuvier.

= Clio, Linne.

= Gleba, Forskal.

— Cavolinia, Abildgaard.

As to the genus Valvatina, Bornemann,1 Fischer2 is evidently in error in stating that it includes living Pteropods, for all the forms which he describes are fossils. It is like- wise probable that most of the latter are not even Pteropods.

The genera Euchilotheca, Fischer ; Flabellulum, Bellardi ; Gamopleura, Bellardi ; Poculina, Bellardi ; Tibiella, Meyer, and the genus Valvatina mentioned above are only known as Tertiary fossils ; and they are further very closely allied to various extant genera.

I completely abstract certain primary fossils usually referred to the Pteropoda. I

1 Die microscop ische Fauna des Septarienthones von Hermsdorf bei Berlin, Zeitsclir. d. deutsch. geol. Gesellsch., Bd. vii.

p. 18.

2 Manuel de Conchy liologie, p. 430.

8

THE VOYAGE OF H.M.S. CHALLENGER.

have a deep conviction that these organisms do not really belong to the group in question, and am firmly of opinion that Pteropods do not occur as fossils till the end of the Lower Tertiary. I shall afterwards revert more explicitly to this point in the anatomical part of the Report, in connection with the origin and phylogeny of the group.

Among the living Thecosomata really known there are, then, strictly speaking, only eight genera, including one new genus established in this Report.

These genera are : —

Limacina, Cuvier. P ercicle, Forbes. Clio, Linne. Cuvierina, Boas.

Cavolinia, Abildgaard. Cymbulia, Peron and Lesueur. Cymbuliopsis, n. gen.

Gleba, Forsk&l.

The following table indicates the chief diagnostic characters : —

Key to the Genera.

I. Calcareous shell quite outside the mantle.

1. Shell twisted into a spiral.

A. Shell with somewhat gentle whorls, a moderately wide opening, and a

columella not prolonged into a recurved rostrum, . . . .

B. Shell with rapidly ascending whorls, with a very wide opening and a

columella prolonged into a recurved rostrum, . . . .

2. Shell straight and bilaterally symmetrical.

A. Shell larger at the aperture than just behind.

a. Shell without constriction behind the aperture,

h. Shell with a constriction immediately behind the aperture,

B. Shell narrower at the aperture than just behind, . . . .

II. Cartilaginous shell covered by the pallial epithelium.

1. Voluminous shell with a marked cavity.

A. Thick shell, with the cavity not extending dorsally to the very end,

B. Shell with thin walls, cavity extending dorsally to the very end,

2. Flattened shell with almost no cavity, ......

Limacina.

Peraclis.

Clio.

Cuvierina.

Cavolinia.

Cymbulia.

Cymbuliopsis.

Gleba.

As to the relations of these eight genera with the other Pteropods, we have already noted in the Systematic Report on the Gymnosomata,1 that Fol doubts whether Cymbulia has not more affinity with the Gymnosomata than with the Thecosomata. Wagner also separates the genus Cymbulia from the Thecosomata, and in order to get over the difficulty without solving it, creates for these animals a third division among the Pteropods, viz., Alata.2

In reality the members of the genus Cymbulia do not differ from the typical Theco- somata which Souleyet included in his family “ Hyales” except in external appearance.

1 Zool. Chall. Exp., part lviii. p. 6.

2 Die Wirbellosen des weissen Meeres, Bd. i. p. 119.

EEPOET ON THE PTEEOPODA.

9

In their entire organisation (existence of a pallial cavity ; number of tentacles ; position of the penis, fins, cerebral ganglia, &c.) they agree with the Thecosomata, as we shall see in our anatomical Eeport. On the other hand, their special characters make it convenient to erect for them a special family, which appears to be a far preferable course to uniting them, as Woodward1 has done, with the Cavoliniidse, in which he has also included the Gymnosomatous Halopsyche.

As to the other Thecosomata, they form a more uniform group, within which one may pass from one form to another without remarking any very considerable modification. It is true, however, that in this group some forms differ from the majority in having the shell twisted into a spiral, as also in the position of the anus and of the pallial cavity. The existence of these last two differences in forms otherwise closely allied will be explained in the anatomical part of the Eeport. The differences just mentioned make it possible to separate the forms in question, and to erect them into the family Limacinkke, which, however, Souleyet unites with the typical Thecosomata.2

As to all the rest, they form a most natural family — Cavoliniidse, from which there is no reason to separate the genus Cuvierinci, under the name of Tripteridse, as Gray 3 and the brothers Adams4 have done. The last mentioned genus in fact differs but very slightly from certain types of Cavoliniidse, such as the species of Clio of the section Creseis, from which indeed they are distinguishable only by the presence of a partition towards the middle of the shell, and by the constriction behind the aperture.

Among the Thecosomatous Pteropods, we thus recognise only three families : —

1. Limacinidse, including the genera Limacina and Peraclis.

2. Cavoliniidse, ,, „ Clio, Cuvierma, and Cavolinia.

3. Cymbuliidse, ,, „ Cymbulia, Cymbuliopsis, and Gleba.

Family I. Limacinida

1847. Limacinidx , Gray, A List of the Genera of Eecent Mollusca, their synonyms and types, Proc. Zool. Soc. Lond., p. 203.

1859. Spirialidse, Chenu, Manuel de Conchyliologie, t. i. p. 113.

Characters. — Shell external, twisted into a left-handed spiral, with a spiral oper- culum. Animal with a dorsal pallial cavity, and a ventral columellar muscle ; anus situated on the right side.

Description. — The shell, which is always delicate as in other pelagic animals, is of small size, and is translucent with slight colouring. The spire and the operculum differ considerably in form in the various species.

1 A Manual of the Mollusca, p. 204, 1856. 2 Histoire naturelle des Mollusques Pteropodes, p. 32.

3 Catalogue of the Mollusca in the Collection of the British Museum, pt. ii., Pteropoda, p. 23.

4 The Genera of Recent Mollusca, vol. i. p. 54.

(zool. chall. EXP. PART LXV. 1887.)

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10

THE VOYAGE OF H.M.S. CHALLENGER.

The operculum is very delicate, glassy, and transparent. It is fixed by a portion of its surface to the posterior face of the ventral lobe of the foot.

The animal is twisted like the shell which it completely fills, and into which it may be completely retracted. The margin of the mantle bears, on the right-hand side, and somewhat ventrally, a long extensile appendage. The posterior lobe of the foot, which bears the operculum and is topographically ventral, is hollowed out on the middle of its free margin. The fins do not exhibit, towards their distal extremity, the area without muscular fibres which is usually to be observed in the genus Clio }

As regards the systematic relations of the genera and species, the family Limacinidse is still but imperfectly understood. This is in part doubtless due to the small size of the animals which form the family. They have hitherto been but rarely studied, and even in special works on Pteropods are often slurred over, as for instance in the memoirs of Quoy and Gaimard and of Rang. In the same way Troschel and Gegenbaur in their studies on the Pteropods of the Mediterranean have not discussed a single member of this family, and we may also note that Pfeffer, who has published an important description of the Thecosomata in the Hamburg Museum, has quite overlooked the Limacinidse.

The investigation of the numerous specimens of this family which were collected on the Challenger Expedition has enabled me to make an almost complete study of the entire family. The results of my investigation I therefore proceed to submit.

If one considers the living species alone, one finds in the literature of the subject that there are no less than thirty-six different specific names applied to forms referred to this family. In this number I do not include, be it understood, the manuscript species, or those which have been simply recorded without description or figure — Limacina carinata, Jeffreys,2 Spirialis diversa, Monterosato,3 Spiricdis contorta, Monterosato.4 These I evidently could not take into account.

Since the work of Souleyet,5 Boas is the only naturalist who has attempted to make a synthetic study of this group.6

From the researches of these authors it may be concluded that there are now seven species adequately enough known by their shell, operculum, and anatomy to leave no doubt as their systematic position. These species are the following, and in citing them I shall retain the original generic titles, omitting for the present the discussion of their proper generic distribution.

1 Boas considers this space as corresponding to the hollow which separates the small tentacle-like lobe of the fin of some species of Limacina and Clio of the subgenus Creseis, from the margin of this fin (Spolia atlantica, p. 182, pi. v. figs. 70-79).

2 The French Deep-Sea Exploration in the Bay of Biscay, Rep. Brit. Assoc., 1880, p. 387.

3 Nuova rivista delle conchiglie Mediterranee, p. 50.

4 Ibid., p. 50.

5 Histoire naturelle des Mollusques Pteropodes.

6 Spolia atlantica, pp. 38-50.

REPORT ON THE PTEROPODA.

11

1. Atlanta injlata, d’Orbigny.

2. Atlanta lesueurii, d’Orbigny.

3. Clio helicina, Pliipps.

4. Spirialis australis, Eydoux and Souleyet.

5. Limacina balea, Moller.

6. Atlanta trochiformis, d’Orbigny.

7. Atlanta bulimoides, d’Orbigny.

The considerable number (twenty-nine) of other forms described (often very imperfectly, and without examination of the animals) includes the following forms. I should rather say did include the following when I undertook this Report, for as the result of the investigation about to be recounted, certain changes in the grouping become necessary. Thus one species in Group III. must be referred to Group I., while two species of Group II. must be placed at the end of the seven species chronicled above.

I. One, which I cannot regard as a Pteropod : Limacina turritelloides, Boas.

II. Four, which appear to me to belong quite clearly to the Thecosomatous Limacinidse : —

Embolus triacanthus, Fischer. Limacina helicoides, Jeffreys.

Limacina antarctica, Woodward. Atlanta reticulata, d’Orbigny.

III. Four, which seem to me much less certain, but in regard to which the reports of those who have studied them are not sufficient to admit of a positive conclusion as in the case of the two preceding groups. Until further information is forthcoming they must be regarded as doubtful : —

Limacina (?) cucullata, Gould. Agadina stimpsoni, A. Adams.

Agadina gouldi, A. Adams. Atlanta rotunda, d’Orbigny.

IV. Finally, all the other specific titles are synonyms either of some of the seven well-known species, or of the four included in the second group : —

Argonauta artica, Fabricius, .

Limacina helicialis, Lamarck, . Spiratella limacina, de Blainville, Limacina pacifica, Dali,

Peracle jlemingii, Forbes,

Limacina balea, Moller,

Scaea stenogyra, Philippi,

Spirialis goiddii, Stimpson,

Spirialis Jeffrey sii, Forbes and Hanley, . Spirialis macandrei, Forbes and Hanley, Heterofusus alexandri, Verrill,

Limacina naticoides, Rang,

j> = Clio helicina, Phipps.

• = Heterofusus retroversus, Fleming.

= Atlanta trochiformis, d’Orbigny.

12

THE VOYAGE OF H.M.S. CHALLENGER.

| = Atlanta lesueurii, d’Orbigny.

\ = Atlanta injlata, d’Orbigny.

J

= Atlanta reticulata, d’Orbigny.

To these known species I can also add a new form included in the Challenger collection, which may without hesitation be referred to Group II. of undoubted Limacinidse. Another form, which cannot be identified with any of those hitherto known, seemed at first to be referable to Group III. above, but subsequent examination has shown that it must rather be placed in Group I. aloug with another species of the same nature.

How are these different species to be distributed throughout the family ? Or, in other words, how many distinct genera can be distinguished.

The question is indeed a most difficult one, and there are almost as many opinions on the subject as there are investigators of the group. Very few of the expressed opinions, however, claim much serious attention, for there has hardly been any previous attempt to make a systematic synthesis of the family Limacinidse.

If we turn to the table of genera (p. 8) we see that twelve generic titles have been invented for living Thecosomata with spiral twisting, that is to say, just the same number of genera as there are certainly admissible species. I append the titles in chronological order : —

Atlanta rangii, d’Orbigny (?), .

Spirialis ventricosa, Eydoux and Souleyet, Spirialis rostralis, Eydoux and Souleyet, Protomedea elata, 0. G. Costa,

Limacina scaphoidea, Gould, .

P eracle physoides, Forbes,

Spirialis clathrata, Eydoux and Souleyet, Spirialis recurvirostra, A. Costa,

1. Limacina, Cuvier, 1817.

2. Heterofusus, Fleming, 1823.

3. Spiratella, de Blainville, 1824,

4. Heliconoides, d’Orbigny, 1836.

5. Spirialis, Eydoux and Souleyet, 1840.

6. Helicophora, Gray, 1842.

7. P eracle, Forbes, 1844.

8. Scsea, Philippi, 1844.

9. Campylonaus, Gray, 1847.

10. Euromus, A. and H. Adams, 1858.

11. Protomedea, 0. G. Costa, 1861.

12. Embolus, Jeffreys, 1869.

What increases the confusion resulting from this superfluity of generic nomenclature in a group with so few forms, is the fact that several of these names have been used in different ways by different authors. Hence a complex and contradictory set of synonyms.

REPORT ON THE PTEROPODA.

13

Gray (1850),1 Gould (1852), 2 and Boas (1886) 3 have tried to simplify the matter by uniting all the known species in a single genus with the oldest title, Limacina, Cuvier. But it must be noted that Gould knew but few species of Limacinidse, and that for one form which he regarded as new he even thought that it might be well to create a new genus. Jeffreys 4 also unites in a single genus, Limacina, all the species which he discusses except Atlanta inflata, d’Orbigny, for which he establishes a genus Embolus, although a certain species which he calls Limacina. i differs more from the typical Limacina than does Atlanta inflata. And besides, as we shall afterwards see, that solution of the difficulty which seeks to unite in a single genus all the living Limacinidse is not in conformity with the differences of organisation exhibited by the various types.

There is only one way of restoring order to the confused nomenclature, and that is to find for each generic title the connotation given to it by its inventor, and the type to which it was originally applied. In this way alone can one recognise with any certainty what are the synonymous titles, and eliminate the more recent tautologies.

Let us then see what titles ought to be expelled from the nomenclature.

I. It is necessary first of all to abstract the genus Agadina, Gould, which, as we shall immediately see, has been too inadequately and imperfectly diagnosed to admit of any accurate conception being framed in regard to the organisms to which it ought to be applied.

II. The genus Spiratella was founded in 1824 by de Blainville for Clio helicina, Phipps. But for the same species the genus Limacina was erected by Cuvier in 1817. The name Spiratella need not therefore be retained.

III. The genera llcliconoides, d’Orbigny (1836), Spirialis, Eydoux and Souleyet (1840), and Helicophora, Gray (1842), are all based upon the same series of small forms, but without reference to any particular type. This series includes among its species three forms of shell, and to this it is due that the above titles have been used with different connotations by different authors (the brothers Adams, Bronn, Carus, Fol, Sars, &c.).

These forms of shell are — (1) a more or less elevated spiral with a simple lip ; (2) a depressed spiral with a rostrated lip ; and (3) with a very large aperture and a columella prolonged into the rostrum ; and they have all received different names. The adoption of these new names evidently involves the abandonment of the titles noted above in the original sense of their authors. The new names corresponding to the three forms of shell are as follows : —

1 Catalogue of the Mollusca in the Collection of the British Museum, pt. ii., Pteropoda.

2 The Mollusca and Shells of the U.S. Exploring Expedition.

3 Spolia atlantica.

4 New and peculiar Mollusca, &c., procured in the “ Valorous ” Expedition, Ann. and Mag. Nat. Hist., ser. 4, vol. xix. p. 337.

14

THE VOYAGE OF H.M.S. CHALLENGES.

1. Heterofusus, Fleming (1823), and Scaea, Philippi (1844) ; the former based on Heterofusus retroversus, Fleming, the latter on Scsea stenogyrci, Philippi. But as these two species are identical, the two generic titles are absolutely synonymous, and the more recent ought to disappear.

2. Protomedea, 0. G. Costa (1861), and Embolus, Jeffreys (1859) ; the former based on Protomedea elata, 0. G. Costa, and the latter on Atlanta injlata, d’Orbigny. But as the two species are synonymous, the two generic titles are equally so ; and since the name Protomedea was applied in 1834, by de Blainville, to a Coelenterate, it ought to disappear.

3. Peracle, Forbes (1844), Campylonaus, Gray (1847), and Euromus, A. and H. Adams (1858) : the two last based on Atlanta reticulata, d’Orbigny ( = Spirialis clathrata, Eydoux and Souleyet). and the first on Peracle physoides, Forbes. But as these two specific types are now recognised to be identical, the three generic titles are obviously so too, and the two more recent ought to be disused.

Having reached this stage of our critical review, we see that the maximum number of generic titles which can be adopted for the Limacinidse does not exceed those four — Limacina, Heterofusus, Embolus, and Peracle — since we may abstract Heliconoides ( = Spirialis — Helicophor a), this genus being succeeded by the three generic titles referring to the three forms of shell which it includes.

But are Heterofusus and Embolus really distinct, with this simple difference, that in the second the spire is depressed and the lip rostrate ? This can hardly be, for in almost all the genera of Gastropods there are species with short and others with elongated spirals, and the same is true of the rostrate lip. Thus in a group adjacent to the Limacinidse, the important genus Clio ( = Cleodora) exhibits nearly related species, some with a rostrum on the dorsal surface and others without. Nevertheless these forms are much too closely allied to be generically separated, and ought not the same to apply to Heterofusus and Embolus ? Both exhibit in fact an umbilicate shell, with whorls increasing somewhat gently, and a semilunar operculum, with a right-handed spiral of few turns ; nor do the animals exhibit any difference in their structure.

But besides having these characters in common, they share them with Limacina, from which they do not differ in any character sufficient to establish a generic distinction, although, as I have already noted, the reverse has been maintained by Gray, Gould, Boas, and to a certain extent by Jeffreys. It must be remarked on the other hand that Souleyet, who created the genus Spirialis (including Heterofusus and Embolus), recognised that it ought to be united with Limacina if there were an operculum in the latter.1 But it is now sufficiently demonstrated that in Limacina an operculum does exist.

It is true that Sars maintains the generic distinction of Limacina and Spirialis (in

1 Voyage de la Bonite, Zoologie, t. ii. p. 211.

REPORT OX THE PTEROPODA.

15

the restricted sense of Heterofusus), principally on the ground of the transverse strise (at right angles to the axis), which are found in Lirnacina helicina. But this character cannot be regarded as of the value of a generic distinction. If we turn for instance to a group but slightly removed from the Limacinidae, the species of Clio of the subgenus Creseis, we see that Clio chierchiae, Boas, also possesses these transverse strise which are wholly absent in the other three species of the same subgenus. Yet one would not on that account dream of establishing a generic distinction on that simple fact, and a fortiori one cannot separate Lirnacina (s. str.) from “ Spirialis.”

As to the genus Peraclis, Forbes, it is so distinct that it must be retained, although d’Orbigny has referred its typical species to Heliconoides, Souleyet and A. Costa to Spirialis, and Gray, Jeffreys, and Boas to Lirnacina.

Peraclis differs indeed from the genus Lirnacina (as this has been defined above) in having a shell which is not umbilicate, has a few whorls ascending very rapidly, a larger aperture, a columella prolonged into a rostrum twisted into a spiral, and, further, in possessing a subcircular operculum, with a multispiral, left-handed coil. To this operculum neither d’Orbigny, Souleyet, nor Boas have attached the degree of import- ance demanded by its peculiar structure. But even if we do not take account of these differences, the structure of certain portions of the animal of Peraclis separates it markedly from all other Limacinidae, as we shall afterward see, and necessitates the formation of a distinct group, opposed to all the rest of the family.

From the foregoing it results that there are among the living Limacinidae only two different genera, Lirnacina and Peraclis, which may be readily distinguished by turning to the synoptic table of genera (p. 8).

Lirnacina / Cuvier.

1817. Lirnacina, Cuvier, Le Regne animal, t. ii. p. 380.

1823. Heterofusus, Fleming, On a reversed species of Eusus, Mem. Wern. Soc., p. 498.

1824. Spiratella, de Blainville, Mollusques, Diet. d. Sci. Nat., t. xxxii. p. 284, iv. p.

1836. Heliconoides, d’Orbigny (pars), Voyage dans l’Amerique meridionale, t. v. p. 174.

1840. Spirialis, Eydoux et Souleyet (pars), Description sommaire de plusieurs Pteropodes nouveaux ou imparfaitement connus, Rev. Zool., t. iii. p. 235.

1842. Helicophora, Gray, Synopsis of the contents of the British Museum, p. 59.

1844. Scxa, Philippi, Fauna Molluscorum utriusque Siciliie, p. 164.

1861. Protomedea, G. O. Costa {pars), Microdoride Mediterranea, p. 73.

1869. Embolus, Jeflreys, British Conchology, vol. v. p. 114.

Shell umbilicate, with turns gradually increasing ; with a fairly large aperture ; and with a columella not prolonged into a rostrum ; surface smooth or striated. The height of the spire, the form of the surface and that of the aperture, and the size of the

1 Diminutive of Limax.

16

THE VOYAGE OF H.M.S. CHALLENGER.

umbilicus vary according to the species. Operculum semilunar, with a right-handed spiral of a few whorls.

Animal with an indistinctly defined head, which is only marked externally (1) by the lips on the border of the mouth and (2) by the tentacles.

1. Lips : two dorso- ventral folds on the cephalic surface of the fins, united dorsally, diverging ventrally, where they are continued by a fold of the cephalic surface of the fins, and extend laterally to the edge of the fins. They thus enclose a ciliated area which plays an important part in alimentation.1 The mouth, split dorso- ventrally, is situated between these lips, in the angle formed by their union.

2. Tentacles, asymmetrical, the left always less developed and further back than the right. The latter is very long and retractile into a sheath. The tentacles thus exhibit absolutely the same form as those of the Cavoliniidse. Souleyet2 noted that in Limacina helicina the right tentacle seemed to be situated in a sheath, and3 that in his “ Spirialis ” the minuteness of the organs did not permit him to observe whether this was again true. I have been able to convince myself that this sheath exists, not only in Limacina helicina, but in all the small species in which I have been able to study the animal, viz., Limacina injlata, Limacina lesueuri, Limacina australis, Limacina trochiformis.

Fins elongated, enlarged, truncated at their free end. In certain species — Limacina helicina (where the structure has been noted by P. J. van Beneden under the name of tentacles), Limacina antarcticci and Limacina australis (where it was equally distinct) — the fins exhibit, towards the middle of their dorsal margin, a small narrow projecting lobe of a special structure. A similar structure exists in Clio in the subgenus Creseis. I have assured myself that in Limacina injlata, Limacina lesueuri, and Limacina trochiformis this small lobe is not present, and Boas vouches for its absence in Limacina bulimoides. In the other species the animal has not yet been examined.

I cannot attach any great systematic importance to the presence or absence of this minute lobe, or regard it as furnishing basis for generic or subgeneric distinction, for otherwise the entire organisation is so absolutely analogous in all the species of Limacina, and the lobe is present in Limacina australis, and absent in Limacina retroversa, species so closely allied that some authorities have doubted whether they were really distinct.

On turning to the table of species of Limacinidse, it will be seen that there are only ten species which belong to the genus Limacina properly so called. Of these, seven are well known by their shell, their animal, and their operculum, while the other three are sufficiently well known to enable one to judge with some certainty in regard to their systematic position.

1 See Boas, Spolia atlantica, p. 191. — An identical disposition is found in the Cavoliniidas.

2 Histoire naturelle des Mollusques Pteropodes, p. 60.

3 Voyage de la Bonite, Zoologie, t. ii. p. 209.

REPORT ON THE PTEROPODA.

17

These ten species may be thus distinguished : —

Key to the Species.

I. Shell 'with a toothed lip.

1. A single tooth on the lip, .....

2. Three teeth on the lip, .....

II. Shell without teeth on the lip.

1. Spire very short.

A. Shell with transverse strife (at right angles to the axis).

a. Mouth higher than broad,

b. Mouth broader than high,

B. Shell without transverse striae.

a. "Whorls hardly separated by a suture,

b. Whorls separated by a deep suture,

2. Spire high.

A. Mouth quadrangular, columella arched to the right.

a. Umbilicus widely open,

b. Umbilicus constricted,

B. Mouth oval, columella arched to the left.

a. Umbilicus constricted, spire somewhat short, .

b. Umbilicus very narrow, spire elongated,

Limacina injiata. Limacina triacantha.

Limacina lielicina. Limacina antardica.

Limacina helicoides. Limacina lesueuri.

Limacina australis. Limacina retroversa.

Limacina trochiformis. Limacina bulimoides.

#11. Limacina inflata (d’Orbigny).

1836. Atlanta inflata, d’Orbigny, Voyage dans l’Amerique meridionale, t. v. p. 174, pi. xii. figs. 16-19.

1840. Sp trial is rostralis, Eydoux et Souleyet, Description sommaire de plusieurs Pteropodes

nouveaux ou imparfaitement connus, Revue Zoologique, t. iii. p. 236. 1850. Limacina inflata, Gray, Catalogue of the Mollusca in the Collection of the British

Museum, pt. ii., Pteropoda, p. 31.

1852. Limacina scaphoidea, Gould, The Mollusca and Shells of the U.S. Exploring Expedition,

p. 485, pi. li. fig. 602.

1861. Protomedea data, O. G. Costa, Microdoride mediterranea, p. 74, pi. xi. fig. 5.

1870. Embolus rostralis, Jeffreys, Mediterranean Mollusca, Ann. and Mag. Nat. Hist., ser. 4,

vol. vi. p. 86.

1882. Protomedea rostralis, Fischer, Sur la faune Malacologique abyssale de la Mediterranee,

Comptes rendus, t. 94, p. 120.

Shell, animal, and operculum : for description and figures see Souleyet, Voyage de la Bonite, Zoologie, t. ii. p. 216, pi. xiii. figs. 1-10.

Habitat. — This Limacina is distributed in all the warm seas. It has been recorded from the following localities : —

Atlantic Ocean, from 42° N. to 40° S.; Mediterranean, frequently collected at Naples, where I have often observed it ; found also, as represented by empty shells, in a large number of deep dredgings in the Mediterranean, e.g., off Crete (Jeffreys);2 TEgean Sea (Jeffreys);3 and on different parts of the Mediterranean coast (Sicily, Piedmont, &c.).

1 The species collected by the Challenger are marked by an asterisk.

2 Ann. and Mag. Nat. Hist., ser. 5, vol. xi. p. 401. 3 Ann. and Mag. Nat. Hist., ser. 4, vol. vi. p. 86.

(ZOOL. CHALL. EXP. — PART LXV. 1887.) Ttt 3

18

THE VOYAGE OF H.M.S. CHALLENGER.

Indian Ocean; to the south-east of Arabia (“ Vettor Pisani” Expedition, March 8, 1883); Gulf of Bengal and Ceylon (Kiel Museum); St. Paul and Amsterdam Islands (38° 42' S. lat., 77° 34' E.) (Professor Velain, under the MS. title Spirialis appendiculatus).

Pacific Ocean; China Sea (“Galathea” Expedition); Corea Strait (Jeffreys);1 Honolulu in the Philippines (“Vettor Pisani,” August 28, 1884); North-West Pacific to 48° N. (“Galathea”); East Pacific, Panama, &c. (“Vettor Pisani,” March 7, 1884); South-East Pacific to 40° S. (Knocker).2

Challenger Specimens. — I. Living specimens.

Station 142, December 18, 1873; Cape of Good Hope to 46° S.; lat. 35° 4' S., long. 18° 37' E.

Between Stations 162 and 163, April 3, 1874; Melbourne to Sydney ; lat. 38° 7' S., long. 149° 18' E.

Station 175, August 12, 1874 ; Fiji to Raine Island; lat. 19° 2' S., long. 177° 10' E. Station 181, August 25, 1874; Fiji to Raine Island; lat. 13° 50' S., long. 151° 49' E. Station 201, October 26, 1874; Amboina to Samboangan ; lat. 7° 3' N., long. 121° 48' E.

Station 216a, February 16, 1875; Samboangan to New Guinea; lat. 2° 56' N., long. 134° 11' E.

Between Stations 264 and 265, August 24, 1875; Sandwich Islands to Tahiti; lat. 13° 15' N., long. 152° 2' W.

Station 337, March 19, 1876 ; Tristan da Cunha to Ascension Island ; lat. 24° 38' S., long. 13° 36' W.

On April 26, 1876; off St. Vincent (Cape Verde Islands); lat. 16° 49' N., long. 25° 14' W.

II. Deposit shells.

Station VIII., February 12, 1873; off Canary Islands; lat. 28° 3' 15" N., long. 17° 27' 0" W.; depth, 620 fathoms; bottom, volcanic mud.

Station 3, February 18, 1873 ; Tenerife to Sombrero Island; lat. 25° 45' N., long. 20° 14' W.; depth, 1525 fathoms; bottom, hard ground.

Station 23, March 15, 1873 ; off Sombrero Island; lat. 18° 24' N., long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

Station 24, March 25, 1873; off Culebra Island; lat. 18° 38' 30" N., long. 65° 5' 30" W.; depth, 390 fathoms; bottom, Pteropod ooze.

Station 32b, April 3, 1873; St. Thomas to Bermuda; lat. 32° 10' N., long. 64° 52' W.; depth, 950 fathoms; bottom, coral mud.

1 Notice of some Shells dredged by Captain St. John, R.N., in Corea Strait, Journ. Linn. Soc. Lond. (Zool.), vol. xiv. p. 423, 1878.

2 On Pelagic Shells collected during a Voyage from Vancouver Island to this Country, Proc. Zool. Soc. Lond.,

p. 616, 1868.

/

EEPOET ON THE PTEEOPODA.

19

Station 33, April 4, 1873 ; off Bermuda; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

Station 75, July 2, 1873 ; off Fayal (Azores) ; lat. 38° 38' 0"N., long. 28° 28' 30" W.; depth, 450 fathoms ; bottom, volcanic mud.

Station 76, July 3, 1873 ; off the Azores; lat. 38° 11' N., long. 27° 9' W.; depth, 900 fathoms ; bottom, Pteropod ooze.

Station 78, July 10, 1873 ; off the Azores; lat. 37° 26' N., long. 25° 13' W.; depth, 1000 fathoms; bottom, volcanic mud.

Station 85, July 19, 1873 ; off Palma Island; lat. 28° 42' N., long. 18° 6' W.; depth, 1125 fathoms; bottom, volcanic mud.

Station 120, September 9, 1873 ; off the coast of South America, between Pernam- buco and Bahia; lat. 8° 37' S., long. 34° 28' W.; depth, 675 fathoms; bottom, red mud.

Station 122, September 10, 1873 ; off the coast of South America, between Pernam- buco and Bahia; lat. 9° 5' S., long. 34c 50' W.; depth, 350 fathoms; bottom, red mud.

Station 174, August 3, 1874; off Kandavu Island; lat. 19° 6' 0" S., long. 178° 14' 20" E.; depth, 140 fathoms ; bottom, coral mud.

Station 185, August 31, 1874 ; off Raine Island; lat. 11° 35' 25" S., long. 144° 2' 0" E.; depth, 135 fathoms; bottom, coral sand.

Station 219, March 10, 1875; Admiralty Islands to Yokohama; lat. 1° 54' 0" S., long. 146° 39' 40" E.; depth, 150 fathoms; bottom, coral mud.

Station 335, March 16, 1876; Tristan da Cunha to Ascension Island; lat. 32° 24' S., long. 13° 5' W.; depth, 1425 fathoms; bottom, Pteropod ooze.

Observations. — I regard the specimens brought by Mr. Ch. Velain from the Islands of St. Paul and Amsterdam (French Transit of Venus Expedition, 1874) as identical with the above species. They were described under the MS. title Spirialis appendiculatus, and are characterised by the fact that “ the last whorl exhibits on its dorsal region a narrow, flattened surface, corresponding to the rostrum of the free margin” (M. Velain’s MS.).

In almost cosmopolitan animals like Limacina infiata and other Thecosomata, it must be noted that there is a greater expression of variability than in species of less extensive distribution. For this reason the creation of new species must not be accepted without full consideration. Many of the so-called “ species ” are at most local varieties, and in the case just noticed, the difference emphasised by M. Velain is of minimum importance, and may be observed on specimens from other sources.

It must have been by a slip of the pen that Jeffreys1 has associated this form with “ Spirialis macandrei Forbes and Hanley ( = Limacina retroversa). With some 1 On the Marine Testacea of the Piedmontese Coast, Ann. and Mag. Nat. Hist., ser. 2, vol. xvii. p. 180.

20

THE VOYAGE OF H.M.S. CHALLENGER.

hesitation the same author1 also unites Bellerophon minuta, Forbes,2 with the present species. But the perfect bilateral symmetry of this very minute shell makes it more probable that it is only a young Oxy gyrus keraudreni (Heteropod).

*2. Limacina triacantha (Fischer) (PI. I. figs. 1, 2).

1882. Embolus triacanthus , Fischer, Diagnoses d’especes nouvelles de Mollusques recueillis

dans le cours de l’Expedition scientifique de l’aviso le Travailleur (1880, 1881), Journ. de Conchyl., t. xxx. p. 49.

Characters and Description. — Smooth globular shell, flattened above. Spire very short. Three whorls, expanded and overlapping, lying almost in the same plane as in the preceding species. Suture well marked. Mouth large and widened ; lip with three teeth, one above almost on the suture, one inferior, and the third on the lower half on the face of the longer portion of the curve. The two last teeth are the largest, and with each tooth there corresponds a longitudinal rib, somewhat narrow and projecting, parallel to the axis of the shell. The two superior ribs do not extend over the whole of the last coil. Straight columella. Narrow umbilicus. Colour wThitish, the three ribs brown.

Dimensions. — The maximum diameter and height of the shell are almost equal, and measure 4|- mm. in the larger specimens.

The animal and the operculum are unknown.

Habitat. — Atlantic Ocean, to the south of Spain, at a depth of 1205 metres.

Challenger Specimens. — Deposit shells.

Station 23, March 15, 1873 ; off Sombrero Island; lat. 18° 24' N., long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

Station 24, March 25, 1873 ; off Culebra Island ; lat 18° 38' 30" N., long. 65° 5' 30" W.; depth, 390 fathoms; bottom, Pteropod ooze.

Station 33, April 4, 1873 ; off Bermuda; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

Station 76, July 3, 1873; off the Azores; lat. 38° 11' N., long. 27° 9' W.; depth, 900 fathoms ; bottom, Pteropod ooze.

Station 85, July 19, 1873 ; off Palma Island ; lat. 28° 42' N., long. 18° 6' W.; depth, 1125 fathoms; bottom, volcanic mud.

Observations. — It is quite likely that Embolus elatus, Seguenza3 (not Protomedea elata, Costa), from the Sicilian Pliocene is identical with the above species. The diagnosis,4

1 On Mediterranean Mollusca, Ann. and Mag. Nat. Hist., ser. 4, vol. vi. p. 86.

3 Report on the Mollusca and Radiata of the iEgean Sea, &c., Rep. Brit. Assoc., p. 186, 1843.

3 Studii stratigraphici sulla formazione pliocenica, Bull, del R. Gomit. geol., fasc. 5, 6, p. 148, 1875.

4 Studii paleontologici sulla fauna malacologica dei sedimenti pliocenici depositati a grandi profondita, p. 31.

REPORT OX THE PTEROPODA.

21

unaccompanied by any figure, does not, however, admit of certain decision on this point.

The fact that this species has only been found in the deep-sea deposits, and that over a wide area, but has never been collected alive at the surface, raises the question whether it be not really extinct. The remains of fossil Elasmobranchs and Cetaceans found at the bottom of modern seas make this hypothesis more plausible.

Although neither the animal nor the operculum of Limacina triacantha have been as yet observed, there cannot be any doubt that the form in question is a Pteropod. It is indeed difficult to decide, in the absence of the animal, that an empty shell, twisted in a left-handed spiral, really belongs to the Thecosomatous Pteropods and the group Limacinidse, and not to some Gastropodous group, but in the present case there can hardly be any hesitation, as is shown by the following characters

1. The constancy of the left-handed spiral of the shell, which is observed in all the specimens, shows that we have not to deal with an abnormal left-handed example of a right-handed Gastropod.

2. The great breadth of the transverse diameter is not what is normally found in left-handed Gastropods, which usually exhibit an elongated spiral.

3. The thinness of the test is also suggestive.

4. The predominance of Thecosomatous Pteropod shells in the sediments from which the present species was dredged is in itself an argument.

5. The numerous resemblances between the species and Limacina inflata suggest a close affinity.

3. Limacina helicina (Phipps).

1774. Clio helicina, Phipps, A voyage towards the Xorth Pole, p. 195.

1774. Clione helicina, Pallas, Spicilegia zoologica, fasc. x. p. 38.

1780. Arcjonauta arctica, Fabricius, Fauna grcenlandiea, p. 386.

1819. Limacina helicialis, Lamarck, Histoire naturelle des animaux sans vertebres, t. vi. p. 291.

1824. Spiratella limacina, de Blainville, Diet. d. Sci. Xat., t. xxxii. p. 284.

1832. Spiratella arctica, Deshayes, Encyclopedie methodique, Vers, t. iii. p. 138.

1841. Limacina arctica, Moller, Bemaerkninger til slaegten Limacina, Krpyer, Xat. Hist. Tidsskr.,

1 Raekke, Bd. iii. p. 488.

1852. Limacina helicina, Souleyet, Histoire naturelle des Mollusques Pteropodes, p. 61.

1872. Limacina pacifica, Dali, Description of sixty new forms of Molluscs from the West Coasts

of Xorth America and the Xorth Pacific Ocean, Amer. Journ. of Conch., vol. vii. p. 138.

For description and figures, I refer to Sars, Mollusca regionis arctic® Norvegise (1878), p. 328, pi. 29, fig. 1.

Habitat. — The area of distribution is similar to that of Clione limacina. — Davis Strait ; Hudson Strait ; Greenland ; Iceland ; Jan Meyen Island ; Southern Norway ; White Sea (Wagner); Spitzbergen ; Nova Zembla ; Sea of Okhotsk; North Pacific: Monterey,

22

THE VOYAGE OF H.M.S. CHALLENGER.

South Alaska (35° 50' N.) (Dali) ; Arctic Ocean : Point Barrow (surface temperature, 40o,2 F. to 42°) (Dali);1 Aleutian Islands (Krause).

Observations. — I. As in all other species of Limacina there is an operculum, but it is caducous in the older specimens. I emphasise the presence of this operculum, because recent works, such for instance as Claus’s Textbook, still characterise Limacina (s. str. type Limacina helicina) by the absence of this structure. In 1878 Sars definitely demonstrated its existence.

The caducous character of the structure is no isolated fact, for we know not only genera [Fleur otoma, Voluta, &c.) in which certain species have, and others have not, an operculum, but also species in which it is sometimes present, sometimes absent, according to the individual ( Volutharpa ampullacea, Middendorf).

II. I consider Limacina pacifica, Dali, as identical with Limacina helicina. In fact, according to Dali and Krause, this form differs from Limacina helicina only in having more whorls on its spire, and in the absence of an operculum. But these are precisely the characters of the adult Limacina helicina, with which Limacina pacifica is therefore identical.

#4. LAmacina antarctico, Woodward (PI. I. figs. 3, 4).

1856. Limacina antarctica, Woodward, A Manual of the Mollusca, p. 207, nomen tantum,

pi. xiv. fig. 4.

Characters and Description. — Subdiscoidal, flattened shell, with a spire very slightly elevated, rather depressed. Six whorls, ribbed superiorly like those of Limacina helicina, and, in spite of the slight elevation of the spire, quite distinct, and separated by a wrell- defined suture. The whorls are rounded externally and interiorly, the last is much expanded. Large mouth, broader than high, rounded off externally, and not prolonged into an angle. Arched columella. Large umbilicus, not surrounded by a keel as in Limacina helicina. Transverse striae, perpendicular to the axis, arched, regular, and equidistant.

Dimensions. — Maximum diameter 4 to 5 mm.; the height equal to about half the diameter.

Operculum unknown, probably like that of Limacina helicina, and caducous in the adult specimens, which alone have been examined.

Animal very like that of the preceding species. The anterior (dorsal) marginal lobe of the fin is very small, though perhaps somewhat contracted in the only specimen in which I was able to examine it. The posterior lobe of the foot is markedly hollowed out on its free margin. Tentacles like those of Limacina helicina ; the left rudimentary, the right very long, situated in a sheath, and further forward than the left.

1 Report on the international North Polar Expedition to Point Barrow, 1885, Report on the Mollusks, p.

REPORT ON THE PTEROPODA.

23

Habitat. — Antarctic Ocean, where it seems to replace Limacina helicina, between 63' and 64° S. lat. (Eoss, under the title “ A rgonauta arctica”).

Challenger Specimen. — Living. Station 153, February 14, 1874; in vicinity of Antarctic ice; lat. 65° 42' S., long. 79° 49' E.

Observation. — The single specimen in the Challenger collection had its shell quite broken into small fragments. The description of the shell has been based on the unpub- lished figures of Hooker (1840). Two of these are reproduced on PI. I. figs. 3, 4, entirely on the responsibility of Hooker.

#5. Limacina helicoides, Jeffreys (PI. I. fig. 5).

1877. Limacina helicoides, Jeffreys, New and peculiar Mollusca of the Family Eulimidae and

other Families of Gastropoda as well as of the Pteropoda, procured on the “ Valorous ” Expedition, Ann. and Mag. Nat. Hist., ser. 4, vol. xix. p. 338.

Characters and Description. — Shell smooth and shining, with a depressed, but not flattened spire, of three or four whorls, rounded but not expanded, with a continuous surface, that is to say, only separated by a slightly marked, though distinct suture. Aperture somewhat elongated, and angular anteriorly. Columella twisted in a spiral.

Colour. — Hornv brown.

J

Dimensions. — Height and transverse diameter almost equal, measuring 3 ‘75 mm.

Operculum and animal unknown. This species is perhaps in the same position as Limacina triacantha.

Habitat. — Atlantic Ocean to the north of the Equator, always at the bottom, with the shell empty : — “ Valorous ” Expedition, Station 12 ; lat. 56° IP N., long. 37° 41' W.; at a depth of 1450 fathoms. “Porcupine” Expedition (1869), west of Ireland, Station 28; lat. 56° 44' N., long. 12° 52' W.; at a depth of 1215 fathoms. “Porcupine” Expedition (1870), Station 17, Bay of Vigo (not Bay of Biscay as Jeffreys says1); lat. 39° 42' N., long. 9° 43' W.; at a depth of 750 to 1095 fathoms. “ Travailleur ” Expedition (1800), Bay of Biscay.2

Challenger Specimen. — Deposit shell.

Station 78, July 10, 1873 ; off the Azores ; lat. 37° 26' N., long. 25° 13' W.; depth, 1000 fathoms; bottom, volcanic mud.

1 Ann. and Mag. Nat. Hist., ser. 4, vol. xix. p. 338.

- Jeffreys, The French Deep-Sea Exploration in the Bay of Biscay, Rep. Brit. Assoc., 1880, p. 387.

24

THE VOYAGE OF H.M.S. CHALLENGED.

#6. Limacina lesueuri (d’Orbigny).

1836. Atlanta lesueurii, d’Orbigny, Voyage dans l’Amerique meridionale, t. v. p. 177, pi. xx. figs. 12-15.

1836. Atlanta rancjii, d’Orbigny, Voyage dans l’Amerique meridionale, t. v. p. 176, pi. xii. figs. 25-28.

1840. Spinalis ventricosa, Eydoux et Souleyet, Description sommaire de plusieurs Pteropodes

nouveaux ou imparfaitement connus, Revue Zoologique, t. iii. p. 236.

1850. Limacina ventricosa, Gray, Catalogue of the Mollusca in the Collection of the British

Museum, pt. ii., Pteropoda, p. 32.

1886. Limacina lesueurii, Boas, Spolia atlantica, K. dansk. Vidensk. Selsk. Skriv., 6 Raekke,

Bd. iv. p. 46, pi. iii. figs. 33, 34.

For description and figures I refer to Souleyet.1 I shall restrict myself to noting that in the form of its aperture, columella, and umbilicus, this species is closely allied to Limacina australis and Limacina retroversa, with which it forms a very natural sub- group. Though the spire is depressed, it preserves none the less the distinctness of its whorls, which are separated by a very well defined suture.

Animal without a small lobe on the anterior dorsal margin of the fin.

Habitat. — The following localities have been recorded : — Atlantic Ocean, from 36° S. (d’Orbigny) to the Bay of Biscay (Pfeffer).2 Indian Ocean, Islands of St. Paul and Amsterdam (Velain, under MS. title Limacina crossei). West Pacific Ocean, 30° N. lat., 170° W. long. (“Galathea” Expedition), towards Batavia (Boas);3 East Pacific Ocean (d’Orbigny), to 42° S. lat. (Knocker).

Challenger Specimens. — I. Living specimens.

Between Stations 162 and 163, April 3, 1874; on the route from Melbourne to Sydney; lat. 38° 7' S., long. 149° 18' E.

Station 175, August 12, 1874; Fiji to Raine Island ; lat. 19° 2' S., long. 177° 10' E.

Station 216a, February 16, 1875 ; north of New Guinea; lat. 2° 56' N., long. 134° 11' E.

Between Stations 246 and 247, July 4, 1875 ; Yokohama to Sandwich Islands; lat. 36° 42' N., long. 171° 46' E.

Between Stations 264 and 265, August 24, 1875 ; Sandwich Islands to Tahiti; lat. 13° 15' N., long. 152° 2' W.

Station 337, March 19, 1876; Tristan da Cunha to Ascension Island; lat. 24° 38' S., long. 13° 36' W.

On April 26, 1876 ; off St. Vincent (Cape Verde); lat. 16° 49' N., long. 25° 14' W.

On May 7, 1876 ; off the Azores; lat. 34° 22' N., long. 34° 23' W.

1 Voyage de la Bonite, Zoologie, t. ii. p. 216, pi. xiii. figs. 11-16.

2 Uebersicht der auf S.M. Schiff Gazelle und von Dr. Jagor gesammelten Pteropoden, Monatsber. d. k. preuss. Akad. d. fViss. Berlin, p. 245, 1879.

3 Spolia atlantica, p. 47.

REPORT OK THE PTEROPODA.

II. Deposit shells.

Station VIII., February 12, 1873; off Canary Islands; lat. 28° 3' 15" N., long. 17° 27' 0" W.; depth, 620 fathoms; bottom, volcanic mud.

Station 3, February 18, 1873; Tenerife to Sombrero Island; lat. 25° 45' N., long. 203 14' W.; depth, 1525 fathoms; bottom, hard ground.

Station 23, March 15, 1873 ; off Sombrero Island; lat. 18° 24' N., long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

Station 24, March 25, 1873; off Culebra Island; lat. 18° 38' 30" N., long. 65° 5' 30" W.; depth, 390 fathoms; bottom, Pteropod ooze.

Station 33, April 4, 1873 ; off Bermuda; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

Station 85, July 19, 1873 ; off Palma Island; lat. 28° 42' N., long. 18° 6' W.; depth, 1125 fathoms ; bottom, volcanic mud.

Station 120, September 9, 1873; off the coast of South America, between Pernam- buco and Bahia; lat. 8° 37' S., long. 34° 28' W.; depth, 675 fathoms; bottom, red mud.

Station 122, September 10, 1873; off the coast of South America, between Pernam- buco and Bahia; lat. 9° 5' S., long. 34° 50' W.; depth, 350 fathoms; bottom, red mud.

Station 185, August 31, 1874; off Raine Island; lat. 11° 35' 25" S., long. 144° 2' 0" E.; depth, 135 fathoms; bottom, coral sand.

Observations. — I. It is very probable that Atlanta rangii, d’Orbigny, which Souleyet 1 has hesitatingly referred to his Spinalis ventricosa, is identical with the above species. But since the somewhat imperfect description and figure of d’Orbigny exclude the possi- bility of absolute certainty, it is better to adopt, as we have done, the specific title lesueuri , although this species does not occur in d’Orbigny’s work till several pages after Atlanta rangii.

II. Atlanta rotunda i of the same authority,2 which Souleyet3 regards as a variety of his Spirialis ventricosa, appears to us very different indeed. In our opinion it is not even a Pteropod, as we shall explain further on in our appendix to the Limacinidse.

#7. Limacina australis (Eydoux and Souleyet) (PL I. fig. 6).

1840. Spirialis australis, Eydoux et Souleyet, Description sommaire de quelques Pteropodcs

nouveaux ou imparfaitement connus, Revue Zoologique, t. iii. p. 237.

Characters and Description. — Smooth shell, with spire somewhat elevated, with a blunted or obtuse apex, with six or seven bulging whorls, separated by a very deep suture,

1 Histoire naturelle des Mollusques Pteropod es, p. 63.

2 Voyage dans l’Amerique m&ridionale, t. v. p. 175, pi. xii. figs. 20-24.

3 Histoire naturelle des Mollusques Pteropodes, p. 63.

(ZOOL. CHALL. EXP. — PART LXV. — 1887.)

Ttt 4

26

THE VOYAGE OF H.M.S. CHALLENGEK.

with the last whorl much expanded and convex, and projecting more in proportion than all the foregoing. Aperture quadrangular, somewhat angled in front ; columella straight, reflected to the right ; umbilicus broad.

Colour. — Milky.

Dimensions. — 2 to 2#5 mm. in height, about 1*5 mm. in maximum diameter.

Operculum approximately oval, with an almost straight columellar margin, and with a spiral portion measuring barely two-fifths of the entire length.

The animal exhibits a small lobe on the dorsal margin of each fin.

Habitat. — Cape Horn (Souleyet).

From its discovery by Souleyet this species was not reobserved until the Challenger Expedition. Jeffreys1 follows Y^rany in noting the coast of Piedmont as a locality of Spirialis australis, and this has been repeated without question by various authors.2 The statement is, however, entirely erroneous, and has in all probability reference to Limacina trochiformis.

The specimens collected by the Challenger show that this species has a somewhat wide distribution round the South Pole, where it occupies, along with Limacina antarctica, a position analogous to that of Limacina retroversa and Limacina helicina in the north.

Challenger Specimens. — Living.

Station 146, December 29, 1873; Marion Island to Crozets; lat. 46° 46' S., long. 45° 31' E.

Station 149, January 9, 1874 ; at Kerguelen Island; lat. 49° 8' S., long. 70° 12' E.

Station 150, February 2, 1874 ; Heard Island; lat. 52° 4' S., long. 71° 22' E.

Between Stations 154 and 155, February 21, 1874; in vicinity of Antarctic Ice; lat. 63° 30' S., long. 89° 8' E.

Observations. — Boas3 has expressed hesitation in regard to the possible specific identity of Limacina australis, Limacina retroversa, and Limacina trochiformis. They are, however, as we shall see, three very distinct forms.

In the first place, as regards Limacina trochiformis, it belongs along with Limacina bulimoides to a special group of Limacinse quite different from that to which Limacina australis and Limacina retroversa are to be referred. It is characterised by the presence of a shell with oval, rounded aperture, with the columellar margin reflected to the left, and with a very narrow umbilicus. In Limacina bulimoides and Limacina trochiformis also the animal is without any lobe on the fin. In Limacina australis, on the other hand, the opening of the shell is quadrangular, with the columellar margin reflected to the right, with a very broad umbilicus, and a tentacle-like lobe on the dorsal margin of the

1 On the Marine Testacea of the Piedmontese Coast, Ann. and Mag. Nat. Hist., ser. 2, vol. xvii. p. 180.

2 For instance Weinkauff, Die Conchylien des Mittelmeeres, t. ii. p. 428.

3 Spolia atlantica, p. 46.

REPOET ON THE PTEROPODA.

27

tin. Furthermore, the spire is proportionally much shorter in Limacina trochiformis, ancl the operculum has a form differing from that of all the other species in the large extent of its spiral portion (three-sevenths) and in the convexity of its columellar margin.1 2 In Limacina australis 2 the columellar margin of this operculum is almost rectilinear, and the spiral portion hardly attains to more than a third of the total length. Limacina trochiformis has certainly less affinity with Limacina australis than Limacina lesueuri, in spite of the depressed spiral of the latter.

As to Limacina retroversa, it is certainly more nearly allied to Limacina australis than Limacina trochiformis, but the characters which distinguish it from that form are quite distinct enough to be recognised as specific. Thus the umbilicus of Limacina retroversa, while quite distinct, is very narrow",3 in contrast to that of Limacina australis, which as wre have seen is very broad.4 The spire is pointed in Limacina retroversa, but obtuse in Limacina australis, where the whorls are besides more convex, less numerous, and separated by a shallower suture. Even at first sight Limacina australis is distinguished from Limacina retroversa by the expansion of the last coil and by its projection beyond those in front. Finally, in Limacina retroversa the spiral portion of the operculum is much more reduced than that of Limacina australis .*

8. Limacina retroversa (Fleming).

1788. (!) Turbo lunar is, Gmelin, Systema naturae, i. p. 3587.

1823. Heterofusus retroversus, Fleming, On a reversed species of Eusus, Mem. Wern. Nat.

Hist. Soc., vol. iv. p. 498, pi. xv. fig. 2.

1841. Limacina balea, Mpller, Bemaerkninger til slaegten Limacina, Krpyer, Nat. Hist.

Tidsskr., 1 Raekke, Bd. iii. p. 489.

1844. Peracle flemingii, Forbes, in Thompson, Report on the Fauna of Ireland, Rep. Brit. Assoc., 1843, p. 249.

1844. Sc sea stenogyra, Philippi, Fauna Molluscorum u triusque Sicilise, p. 164, pi. xxv.

fig. 20.

1846. Spirialis stenogyra, Loven, Index Molluscorum litora Scandinaviae occidentalia habitantium,

Oversigt k. Vetensk.-Akad. Forhandl., 1846, p. 4.

1849. Spirialis femingii and Spirialis macandrei, Forbes and Hanley, History of the British

Mollusca and their Shells, vol. ii. pp. 384, 385, pi. lvii. figs. 4,

5,: 6, 7.

1849. (1) Spirialis jeffreysii, Forbes and Hanley, Ibid., vol. ii. p. 386, pi. lvii. fig.,8.

1850. Limacina retroversa, Gray, Catalogue of the Mollusca in the collection of the British

Museum, pt. 2, Pteropoda, p. 33.

1 Souleyet, Voyage de la Bonite, Zoologie, Mollusques, pi. xiii. fig. 33.

2 Souleyet, Ibid., pi. xiii. fig. 24.

3 Sars, Mollusca regionis arcticse Norvegise, pi. 29, figs. 2c, 36.

4 Souleyet, Voyage de la Bonite, Zoologie, Mollusques, pi. xiii. fig. 23.

6 Sars, Mollusca regionis arcticse Norvegise, pi. 29, figs. 2 d, 3 d.

28

THE YOYAGE OF H.M.S. CHALLENGER.

1851. Spirialis gouldii , Stimpson, Description of two new species of shells of Massachusetts,

Proc. Boston Soc. Nat. Hist., vol. iv. p. 8 ; and Shells of New England, p. 27, pi. i. fig. 4.

1857. Eeterofusus balea, Mprch, in Rink, Grpnland geographisk, statistisk og naturhistorisk

heskrevet, p. 86.

1872. Eeterofusus alexandri, Verrill, Recent Additions to the Molluscan Fauna of New

England, &c., Amer. Journ. Sci. and Arts, ser. 3, vol. iii. p. 284.

1878. Spirialis balea and Spirialis retroversa, Sars, Mollusca regionis arcticse Norvegise, pp. 329, 330, pi. 29, figs. 2, 3.

For description and figures see Sars, loc. cit.

Habitat. — North Atlantic, on the coast of America, from 63° N. (Davis Strait) to 39° 53' N. (Massachusetts Bay, Verrill); Iceland; coasts of Europe, from Lofoden Island to 50° N., though not yet recorded from Behring Straits.

All records which mention this species as having been found in more southerly localities, and notably in the Mediterranean, are erroneous, and ought to apply to Limacina trochiformis, with which Limacina retroversa has been confused by Jeffreys,1 Weinkauff,2 Costa,3 and other conchologists. Limacina retroversa is no longer found in the Mediterranean, though it occurs in circa-Mediterranean Pliocene and Quaternary deposits (“ Scsea stenogyra ”).

In the deep-sea deposits this species is found in the North Atlantic over an area extending somewhat further south, and it has thus been dredged in the Bay of Biscay by the French “ Travailleur ” Expedition (1880).4

Observations. — I. Some authorities (Jeffreys, Gould, Sars, Verrill, &c.) regard Hetero- fusus retroversa and Limacina balea as two distinct forms.

Sars supports this in his descriptions and figures. According to him, the two forms differ, apart from size which cannot be regarded as distinctive, especially in the fact that in Limacina balea the surface is longitudinally striated (parallel to the axis of the shell) and that its spire is proportionally longer.

To the first of these two points, it may be answered that in Limacina retroversa the surface also exhibits longitudinal striae, less marked, it is true, but distinctly recognisable,5 and that in Scsea stenogyra, Philippi,6 which Sars identifies with Limacina balea, the surface is on the contrary ‘ 4 laevissima.” This point of distinction does not, therefore, appear conclusive.

1 British Conchology, vol. v. p. 116.

2 Die Conchylien des Mittelmeeres, Bd. ii. p. 486.

3 Pteropodi della fauna del Regno di Napoli, p. 19.

4 Jeffreys, The French Deep-sea Exploration in the Bay of Biscay, Rep. Brit. Assoc., 1880, p. 387.

* Sars, Mollusca regionis arcticse Norvegiae, pi. 29, fig. 3e; Gould, Report on the Invertebrata of Massachusetts, ed. 2, pi. xxvii. figs. 345-348.

6 Philippi, Fauna Molluscorum u triusque Sicilise, pi. xxv. fig. 20.

REPOET ON THE PTEROPODA.

29

As to the argument based on the relative height of the spire, the average proportion

40 32

of height to maximum diameter is 27 in Limacina balea, and 27 in Heterofusus

retroversus. But in Spinalis goulclii, Stimpson, identified by Sars with Limacina balea , and with very well marked transverse striation, the apparently very exact figure given

31

by Stimpson1 exhibits the above ratio as yy less, that is to say, than that of Hetero- fusus retroversus, while in Scsea stenogyra, with smooth surface, the ratio according

37

to Philippi's figure is

It is thus seen that the relative height of the spire varies as well as the striation of the surface, and that the variations of these two features are independent. We are, therefore, led to conclude that Limacina balea and Heterofusus retroversus are not two specifically distinct forms, but belong to a single species which exhibits a certain number of varieties.

#9. Limacina trochiformis (d’Orbigny).

1836. Atlanta troclnformis , d’Orbigny, Voyage dans lAmerique meridionale, t. v. p. 177,

pi. xii. figs. 29-31.

1840. Sjnrialis trochiformis, Eydoux et Souleyet, Description sommaire de quelques Pteropodes

nouveaux ou imparfaitement connus, Revue Zoologique, t. iii. p. 237.

1850. Limacina trochiformis, Gray, Catalogue of the Mollusca in the Collection of the British

Museum, pt. ii., Pteropoda, p. 33.

1852. Limacina naticoides, Rang, Histoire naturelle des Mollusques Pteropodes, pi. x. figs. 1, 2. For description and figures see Souleyet.2

The umbilicus of the shell is very small in this species. The dorsal (anterior) margin of the fin does not exhibit any tentacle-like lobe.

Habitat. — Atlantic Ocean, from 41° N. to 28° S.; Mediterranean, Naples (where I have often observed it alive), Malta (David Bruce); the shell has been dredged at a great number of localities in the Mediterranean — Crete (Jeffreys), &c.; Indian Ocean, south-east of Arabia (Blanford); Pacific Ocean, China Sea (Gray), Malay Archipelago (Copenhagen Museum); Equatorial Pacific to 152° W.; South-east Pacific to 30° S. (d’Orbigny).

Challenger Specimens. — I. Living specimens.

Between Stations 162 and 163, April 3, 1874; Melbourne to Sydney; lat. 38° 7' S., long. 149° 18' E.

Station 216a, February 16, 1875 ; north of New Guinea; lat. 2° 56' N., long. 134° 11' E.

1 Shells of New England, pi. i. fig. 4.

2 Voyage de la Bonite, Zoologie, t. ii. p. 223, pi. xiii. figs. 27-34.

30

THE VOYAGE OF H.M.S. CHALLENGED.

Between Stations 264 and 265, August 24, 1875 ; Sandwich Islands to Tahiti; lat. 13° 15' N., long. 152° 2' W.

Station 337, March 19, 1876 ; Tristan da Cunha to Ascension Island ; lat. 24° 38' S., long. 13° 36' W.

II. Deposit shells.

Station 120, September 9, 1873 ; off the coast of South America, between Pernam- buco and Bahia; lat. 8° 37' S., long. 34° 28' W.; depth, 675 fathoms ; bottom, red mud.

Station 219, March 10, 1875 ; Admiralty Islands to Yokohama; lat. 1° 54' 0" S., long. 146° 39' 40" E.; depth, 150 fathoms; bottom, coral mud.

Observations. — I have already stated that Boas has expressed doubts as to the specific distinctness of Limacina australis, Limacina retroversa, and Limacina trochi/ormis, and I have shown that Limacina australis could not be identified with either of the other two species.

As concerns the latter, they have been deplorably confused by a great many authors, Jeffreys,1 MacAndrew, Weinkauff,2 A. Costa,3 Monterosato, &c., who have attributed to Limacina retroversa a geographical distribution much more extensive than it really possesses, by crediting it with localities such as the Mediterranean, the Canaries, &c., which ought to refer to Limacina trochiformis alone. Limacina trochi/ormis differs however from Limacina retroversa (as also from Limacina australis, which belongs to same group), (1) in the oval form of the mouth, which is rounded anteriorly, and has the columellar margin recurved to the left, in contrast to Limacina retroversa where the mouth is quadrangular, pointed anteriorly, and with a rectilinear columellar margin ; (2) in the constant shortness of the spiral in proportion to its last whorl, and (3) in the formation of the operculum, in which the spiral portion is large in Limacina trochiformis , and very small in Limacina retroversa.

#10. Limacina bulimoides (d’Orbigny).

1836. Atlanta bulimoides , d’Orbigny, Voyage dans l’Amerique m4ridionale, t. v. p. 179, pi. xii.

figs. 36-38.

1840. Sjpirialis bulimoides, Eydoux et Souleyet, Description sommaire de quelques Pteropodes

nouveaux ou imparfaitement connus, Eevue Zoologique, t. iii. p. 238.

1850. Limacina bulimoides, Gray, Catalogue of the Mollusca in the Collection of the British.

Museum, pt. ii., Pteropoda, p. 34.

For description and figures see Souleyet, Voyage de la Bonite, Zoologie, t. ii. p. 224, pi. xiii. figs. 35-42.

1 British Conchology, vol. v. p. 116.

2 Die Conchylien des Mittelmeeres, t. ii. p. 428.

3 Pteropodi della fauna del Regno di Napoli, p. 19.

EEPOET ON THE PTEEOPODA.

31

The umbilicus of the shell is almost imperceptible. There is no tentacular lobe to the fin, as Boas has already noted.

Habitat. — Atlantic Ocean, from 40° S. to 30° N. ; Indian Ocean, south-east of Arabia (“Vettor Pisani” Expedition, March 8, 1885); Pacific Ocean, Botany Bay (Angas);1 China Sea and West Pacific to 40° N. (“Galathea” Expedition); Equa- torial Pacific, South Pacific to 37° S. (Knocker); South-east Pacific (d’Orbigny).2

The empty shells of this species have been gathered from the deep-sea deposits in the Mediterranean, where the species is no longer found alive, in the Aegean Sea (Jeffreys), aud in the Mediterranean dredgings of the “Travailleur” (Fischer);3 in the North Atlantic (by the “Valorous ” Expedition,4 and by the first “Porcupine” Expedition, 1869).

Challenger Specimens. — I. Living specimens.

Between Stations 162 and 163, April 3, 1874 ; Melbourne to Sydney ; lat. 38° 7' S., long. 149° 18' E.

Station 175, August 12, 1874 ; Fiji to Raine Island ; lat. 19° 2' S., long. 17 7° 10' E.

Station 181, August 25, 1874 ; Fiji to Raine Island ; lat. 13° 50' S., long. 151° 49' E.

Station 201, October 26, 1874 ; Amboina to Samboangan ; lat. 7° 3' N., long. 121° 48' E.

Station 243, June 26, 1875 ; Yokohama to Sandwich Islands; lat. 35° 24' N., long. 166° 35' E.

Between Stations 247 and 248, July 4, 1875; Yokohama to Sandwich Islands; lat. 36° 42' N., long. 179° 50' W.

Station 337, March 19, 1876 ; Tristan da Cunha to Ascension Island; lat. 24° 38' S., long. 13° 36' W.

On April 26, 1876 ; off St. Vincent (Cape Verde) ; lat. 16° 49' N., long. 25° 14' W.

Near Station 354, May 7, 1876 ; off Azores; lat. 34° 22' N., long. 34° 23' W.

II. Deposit shells.

Station VIII., February 12, 1873; off Canary Islands; lat. 28° 3' 15" N., long. 17° 27' 0" W.; depth, 620 fathoms; bottom, volcanic mud.

Station 3, February 10, 1873; Tenerife to Sombrero Island; lat. 25° 45' N., long. 20 14' W.; depth, 1525 fathoms; bottom, hard ground.

Station 23, March 15, 1873 ; off Sombrero Island ; lat. 18° 24' N., long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

Station 24, March 25, 1873 ; off Culebra Island ; lat. 18° 38' 30" N., long. 65 5' 30" W.; depth, 390 fathoms; bottom, Pteropod ooze.

Station 32b, April 3, 1873 ; St. Thomas to Bermuda ; lat. 32° 10' N., long. 64 52' W.; depth, 950 fathoms ; bottom, coral mud.

1 Angas, Proc. Zool. Soc. Lond ., 1871, p. 99.

2 It is cited from Sicily after Allery by Tiberi, Ann. Soc. Malacol. Belg., t. xiii. p. 76.

3 Gomptes rendus, t. xciv. p. 1201. 4 Ann. and Mag. Nat. Hist ., ser. 4, vol. xix. p. 33 1 .

32

THE VOYAGE OF H.M.S. CHALLENGER.

Station 33, April 4, 1873 ; off Bermuda; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

Station 85, July 19, 1873 ; off Palma Island; lat. 28° 42' N., long. 18° 6' W r, depth, 1125 fathoms ; bottom, volcanic mud.

Station 120, September 9, 1873 ; off the coast of South America, between Pernam- buco and Bahia ; lat. 8° 37' S., long, 34° 28' W. ; depth, 675 fathoms ; bottom, red mud.

Station 122, September 10, 1873 ; off the coast of South America, between Pernam- buco and Bahia ; lat. 9° 5' S., long. 34° 50' W. ; depth, 350 fathoms ; bottom, red mud.

Station 185, August 31, 1874; off Raine Island; lat. 11° 35' 25" S., long. 144° 2' 0"E.; depth, 135 fathoms; bottom, coral sand.

Station 219, March 10, 1875 ; Admiralty Islands to Yokohama; lat. 1° 54' 0" S., long. 146° 39' 40" E.; depth, 150 fathoms ; bottom, coral mud.

Peraclis,1 Forbes {emend.).

1836. Heliconoides , d’Orbigny (pars), Voyage dans FAmerique Meridionale, t. v. p. 174.

1840. Spinalis, Eydoux et Souleyet (pars), Description sommaire de quelques Pteropodes nouveaux ou imparfaiteinent connus, Revue Zoologique, t. iii. p. 235.

1844. Peracle, Forbes, Report on tbe Mollusca and Radiata of the ZEgean Sea, and on tbeir distribution, considered as bearing on Geology, Rep. Brit. Assoc., 1843,

p. 186.

1847. Campylonaus, Gray (non Benson), A List of tbe Genera of Recent Mollusca, their synonyms and types, Proc. Zool. Soc. Lond., 1847, p. 149.

1858. Euromus, A. and H. Adams, Tbe Genera of Recent Mollusca, vol. ii. p. 613.

1876. Limacina, Jeffreys (pars), New and Peculiar Mollusca of tbe Family Eulimidse and other Families of Gastropoda, as well as of tbe Pteropoda procured in tbe “Valorous” Expedition, Ann. and Mag. Nat. Hist., ser. 4, vol. xix. p. 337.

Characters and Description. — Shell with spire short but projecting, with bulging whorls rapidly increasing towards the very large and elongated aperture, which ends anteriorly in a very sharp angle. Spiral columella, prolonged into an elongated rostrum. No umbilicus. Surface smooth or finely reticulate.

Operculum subcircular, multispiral, left-handed.

Animal previously unknown, or supposed to be identical with that of the other Limacinidse. Krohn2 and Costa3 have observed the living animal, but have not

perceived the differences between it and the true Limacina type. 'The differences are as follows : —

1. Head distinct, prolonged into a proboscis analogous to that of the Cymbullidse (for example the old larvae of Gleba).

1 Per, meaning exaggeration, and aclis, a small javelin, in allusion to the long rostrum of the shelL

2 Beitrage zur Entwickelungsgeschicbte der Pteropoden und Heteropoden, p. 43, under tbe name of .Spvrialis clathrata .

3 At Naples, under tbe name of Spirialis recurvirostra.

REPORT ON THE PTEROPODA.

33

2. Lips with, lateral angles, and united ventrally.

3. Tentacles symmetrical, of the same size and without sheath.

4. Posterior or opercular lobe of the foot broad at the base, instead of being slightly constricted as in Limacina, and less developed in proportion to the fins, which are large, long, truncated at their distal extremity, and without the small tentacle-like lobe.

5. Visceral ganglia forming three distinct masses, as in the Cymbuliidse.

Observations. — I. Boas has made a mistake in figuring the operculum as twisted in a

right-handed spiral.1 The coil is left-handed, as d’Orbigny has represented it.2 This arrangement is quite unique, for in all the operculate Mollusca the twisting of the operculum is in the opposite direction to that of the shell. Atlanta is the only right- handed Mollusc in which the operculum is coiled to the right. In all the left-handed operculate Molluscs the operculum is coiled to the right — Limacina ,3 Triforis ,4 Lseocochlis.5 Peraclis thus forms a remarkable exception.

II. The initial portion of the spire does not project, so that the apex is always obtuse.

III. Boas6 notes in “ Limacina” reticulata ( = Peraclis) a small tentacle-like lobe on the fin as in Limacina helicina; this observation was made on an insufficiently preserved specimen, and has not been figured. I have examined not only the preserved specimen of the Challenger Expedition, but living specimens from the Mediterranean, and am able to state that the fin does not bear any lobe. Costa’s figures 7 are perfectly correct in this respect. Boas must have mistaken a fold of the fin margin for the lobe.

D’Orbigny, the discoverer of the only species as yet known, considered it, as well as all the small forms of Limacina (the Spirialis of Souleyet), as Heteropods of the genus Atlanta. Forbes, who gave a second specific title to the form in question, and created for it the generic title Peracle, also regarded it as a Heteropod. Gray also regarded it as such, under the title Campylonaus.8,

Souleyet was the first to place this form, with a third specific title, among the Pteropods, but was unable to investigate the animal. Subsequently Costa figured the

paired fins of the animal, to which he gave a fourth specific title, and made its position as a Pteropod indisputable.

The structure of the genus has, however, remained quite unknown till now. I have been able to investigate it to some extent, and to show that it is of the highest interest

1 Spolia atlantica, pi. iii. fig. 39.

2 Voyage dans l’Amerique meridionale, t. v. pi. xii. fig. 39.

3 Souleyet, Voyage de la Bonite, Zoologie, Mollusques, pi. xiii. ; Sars, Mollusca regionis arctic® Norvegise, pi. 29.

4 Sars, Iiid., pi. xviii. fig. 31.

5 Sars, Ibid., pi. xviii. fig. 29.

6 Spolia atlantica, p. 50, note 2.

7 Annuario del Museo Zoologico della R. TJniv. Napoli, t. iv. pi. iv. fig. 12.

8 Proc. Zool. Soc. Lond., p. 149, 1847.

(ZOOL. CHALL. EXP. — PART LXV. 1887.)

Ttt 5

34

THE VOYAGE OF H.M.S. CHALLENGER.

and importance in connection with the phylogenetic relations of the different families of Thecosomata. This I shall show in the anatomical portion of this Report.

Key to the Species.

A. Shell with simple lip, .....

B. Shell with lip exhibiting a tooth towards the suture,

Peradis reticulata. Peradis bispinosa.

#1. Peraclis reticulata (d’Orbigny) (PI. I. figs. 7, 8).

1836. Atlanta reticulata, d’Orbigny, Voyage dans l’Amerique meridionale, t. v. p. 178,

pi. xii. figs. 32-35, 39,

1840. Spirialis clathrata, Eydoux et Souleyet, Description sommaire de quelques Pteropodes

nouveaux ou imparfaitement connus, Revue Zoologique, t. iii. p. 138.

1844. Peracle physoides, Forbes, Report on the Mollusca and Radiata of the iEgean Sea,

considered as bearing on geology, Rep. Brit. Assoc., 1843, p. 186.

1865. Spirialis recurvirostra, A. Costa, Di una nuova specie mediterranea di Molluschi

“ Pteropodi ” del gen. Spirialis, Rendiconto d. real. Acad. d. Sci. Napoli, Anno iv. p. 125 (1867); Illustrazione della Spirialis recurvirostra, Annuario del Museo Zoologico della R. Univ. Napoli, t. iv. p. 56, pi. iv. fig. 12.

1870. Spirialis physoides, Jeffreys, in Carpenter and Jeffreys, Report on Deep-Sea Researches,

Proc. Roy. Soc., vol. xix. p. 173.

1876. Limacina physoides, Jeffreys, New and Peculiar Mollusca of the Eulimidse and other

families of Gastropoda, as well as of the Pteropoda procured in the “ Valorous ” Expedition, Ann. and Mag. Nat. Hist., ser. 4, vol. xix. p. 337.

Characters and Description. — Shell elongated, formed of four bulging whorls, sepa- rated by a deep suture, and exhibiting a very slight keel on the side of the spire. The latter is somewhat short, obtuse at its apex, owing to the absence of projection of its initial portion ; the last turn is very large. The opening is very large, elongated, and angled anteriorly. The columella is spiral with a prolonged pointed rostrum, which follows in its curvature the spiral of the columella. The surface exhibits a raised hexagonal reticulation, the sides of the hexagons bearing a regular row of minute teeth.

Colour. — Brownish-yellow.

Dimensions, — Maximum length 4 mm.; diameter 2 ’3 mm.

Operculum. — Glassy, with about four whorls ; the surface of insertion small.

Animal. — Corresponding with the generic description.

Observations. — I. The reticulation of the surface becomes less marked from the apex of the spire towards the aperture. On the first whorls it projects markedly, while towards the mouth it almost disappears, and the colour of the shell becomes clearer. On the

REPORT ON THE PTEROPODA.

empty shells, obtained from deep-sea deposits, the surface is perfectly smooth, and the shell is then clear and translucent, with a brownish-grey colour. This makes me think that the reticulation of the surface is confined to the epidermis.

II. The reason for the numerous titles applied to the present species is that the specimens have been studied in very different conditions.

Hitherto only one author has studied the living Pteropod in its adult state, namely Costa, who described it as Spinalis recurvirostra.

The two oldest descriptions of this species, that of d’Orbigny (under the title Atlanta reticulata ) and that of Souleyet (under the title Spirialis clathrata), refer to young- individuals. This is clearly shown from their smaller size (2|- mm.), the fewer turns in the spiral (three), the incompletely developed columellar rostrum, and the well-developed reticulation towards the aperture.

As to this reticulation, I have noticed that in the single specimen obtained on the Challenger Expedition, which was at the same stage as that observed by d’Orbigny and Souleyet, the markings are hexagonal, and not tetragonal as one might suppose with low- power examination.

Finally, the empty shells- from deep-sea deposits, which have lost their superficial reticulation and brown colour, have been described by Forbes. Jeffreys (1871), and Fischer (1882) 1 under the specific title physoides.

Habitat. — Pacific Ocean, 20° S., 87 3 W. (d’Orbigny) ; perhaps in the Atlantic, at the Canaries (Krohn) f Mediterranean, Naples, during the day, at a depth of 100 metres or more.

The empty shells of this species have been dredged at various points in the Mediterranean ; in the deep-sea dredgings of the “ Travailleur ” (Fischer) ; on the coast of Algiers (“Porcupine” Expedition, 1870, Station 51, 36° 55' N., 1° 10' E.) ; off Crete (Jeffreys),1 2 3 in the AEgean Sea (Forbes), and finally in the North Atlantic (“Valorous” Expedition).4

Challenger Specimens. — I. Living.

Between Stations 264 and 265, August 24, 1875; on the route from the Sandwich Islands to Tahiti; lat. 13° 15' N., long. 152° 2' W.

This single specimen was stained and mounted in balsam. In order to examine the reticulation of the shell and the form of the fins, I had to extract the specimen from the balsam, and in this operation the shell was broken.

II. Deposit shells.

Station 23, March 15, 1873 ; off Sombrero Island; lat. 18° 24' N., long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

1 Comptes rendus, vol. xciv. p. 1201.

2 Beitrage zur Entwickelungsgeschiclite der Pteropoden und Heteropoden, p. 43.

3 Ann. and Mag. Nat. Hist., ser. 5, vol. xi. p. 401. 4 Ann. and Mag. N at. Hist., ser. 4, vol. xix. p. 337.

36

THE VOYAGE OF H.M.S. CHALLENGER.

Station 24, March 25, 1873 ; off Culebra Island; lat. 18° 38' 30" N., long. 65° 5' 30" W.; depth, 390 fathoms ; bottom, Pteropod ooze.

Station 33, April 4, 1873 ; off Bermuda ; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

Station 85, July 19, 1873 ; off Palma Island (Canaries); lat. 28° 42' N., long. 18° 6' W.; depth, 1125 fathoms; bottom, volcanic mud.

Station 122, September 10, 1873 ; off the coast of South America, between Pernam- buco and Bahia; lat. 9° 5' S., long. 34° 50' W.; depth, 350 fathoms; bottom, red mud.

*2. Peraclis bispinosa, n. sp. (PI. I. figs. 9, 10).

Characters and Description. — Shell elongated, smooth on the surface, with three or four bulging whorls on the spiral. The suture is milled, that is to say, the face of the whorls turned towards the spiral, which is somewhat depressed and slightly keeled, exhibits transverse ridges. In consequence of the twisting these ridges come to be disposed radially. The aperture is very large and long ; the lip is hollowed out towards the suture, and bears in front of this hollowing a tooth directed outwards and towards the apex of the shell. Between this tooth and the excavation the margin of the aperture is slightly reflected inwards. The columella is prolonged into a very long rostrum which is straight throughout its entire length.

Colour. — Milky-white.

Operculum and animal unknown.

Dimensions. — Length 7’5 mm.; maximum diameter about 6 mm.

Observations. — I. In the specimens from deep-sea deposits (the only specimens known) the surface is smooth. Perhaps in the living specimens the surface may be reticulated as in Peraclis reticulata.

II. It is possible that the Spirialis diversa of Monterosato 1 was based on young specimens of Peraclis bispinosa. The above species has not yet been described, but Seguenza2 notes in regard to fossil specimens that “ Spirialis diversa ” resembles “ Spirialis recurvirostra ” ( Peraclis reticulata), and that it exhibits a toothed suture.

Challenger Specimens. — Deposit shells.

Station VIII., February 12, 1873 ; off Canary Islands ; lat. 28° 3' 15" N., long. 17° 27' 0" W.; depth, 620 fathoms; bottom, volcanic mud.

Station 33, April 4, 1873 ; off Bermuda; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

Station 75, July 2, 1873 ; off Fayal (Azores); lat. 38° 38' 0" N., long. 28° 28' 30" W.; depth, 450 fathoms ; bottom, volcanic mud.

1 Nuova rivista delle Conchiglie mediterranee, p. 50.

2 Studii paleontologici sulla fauna malacologica dei sedimenti pliocenici depositati a grandi profondita, p. 30.

REPORT ON THE PTEROPODA.

37

Station 76, July 3, 1873; off the Azores; lat. 38° IT' N., long. 27° 9' W.; depth, 900 fathoms ; bottom, Pteropod ooze.

Station 78, July 10, 1873 ; off the Azores ; lat. 37° 26' N., long. 25° 13' W.; depth, 1000 fathoms; bottom, volcanic mud.

Station 85, July 19, 1873; off Palma Island (Canaries); lat. 28° 42' N., long. 18c 6' W.; depth, 1125 fathoms; bottom, volcanic mud.

Appendix to the Limacinida:.

I. Gould has described,1 under the name of “ Limacina (?) cvcullata,” a Mollusc which he found to be different from the forms of Limacina previously described. For this he eventually proposed to erect the new genus Agadinci.

The species and genus are, however, described and figured in a fashion so incomplete, and in addition characterised so insufficiently, that it is impossible to decide with any certainty as to their systematic position. One may, however, notice that according to Gould’s figures the shell, which measures 6 mm. in diameter, exhibits a right-handed spiral which is not the case with any member of the Limacinidse.

One must therefore entertain very grave doubts as to the position of this species. It seems to me most probable that it is a Limacina antcirctica ill-drawn (cf. Gould’s figure with fig. 4, PI. II., after Hooker).

The specimen in question was obtained from the Antarctic Ocean (60° 0' S., 106° 20' E.). I have carefully sought among the Pteropods of the Challenger collection from that region, but have not been able to find anything corresponding to Gould’s description.

A. and II. Adams have nevertheless retained2 among the Limacinidse the title Agadina; and in 1867 A. Affiants described under this generic title two new species, but without any information as to the organisms.

In these, however, in contrast to the Agadina of Gould, the shell is perfectly left- handed, and the mouth does not in any way recall the bell-like form of Limacina cucullata. And furthermore the operculum of one of the forms is described (though without any notice of the direction of the coils) as multispiral. In this there is a resemblance to Peraclis, and there seems some reason therefore to regard the above types as true Limacinidoe.

I have found among the preparations of surface animals collected on the Challenger Expedition, which have been stained and mounted in balsam, one of the species described by A. Adams (Agadina stimpsoni), and another form of the same group, which is, however, quite distinct from either of the species above noted.

Having found several specimens of Agadina stimpsoni and of Agadina, n. sp., I have

1 The Mollusca and Shells of the U.S. Exploring Expedition, p. 486, pi. li. fig. 601.

2 Proc. Zool. Soc. Lond., 1867, p. 309.

38

THE TOY AGE OF H.M.S. CHALLENGER.

sacrificed one of each in order to examine the animals. To do this the specimens had to be removed from the balsam, and the shell destroyed by acetic acid.

I was then able to recognise that the so-called Limacinidse were only Gastropod larvae.

If it be useful to communicate new truths, it is not less necessary to destroy old errors. I have for this reason devoted a few sentences to show that the types of Agadina (in the sense in which A. and H. Adams use the term) are not really Pteropods.

#1. Agadina stimpsoni, A. Adams (PI. I. figs. 11-14).

1867. Agadina stimpsoni, A. Adams, Description of New Species of Shells from Japan, Proc.

Zool. Soc. Lond., 1867, p. 309, pi. xix. fig. 23.

Shell smooth, discoidal, without spire ; three and a half whorls gradually increasing, rolled up in the same plane ; rounded oblique aperture, with slightly bell-shaped margins ; deep umbilicus, with slightly marked rays.

Colour. — Yellowish- white.

Dimensions. — 1 mm. in diameter.

Operculum. — Horny, circular, externally concave, multispiral, with four and a half whorls gradually increasing, left-handed, surface of insertion very large.

Animal bearing on its head a four-lobed velum ; dorsal pallial aperture ; thick columellar muscle ; foot large and strong, bifid in front, with a long broad creeping surface, and bearing the operculum at the posterior end ; no fins.

The small size of this species, and the manipulations which the specimen had to undergo (the action of chloroform to remove the balsam, and of acetic acid to dissolve the shell), after having been stained and mounted in balsam for twelve years, did not allow me to study its structure in any detail. But what has been elucidated is sufficient to enable one to decide the group of Molluscs to which this form belongs, and the stage of development arrived at.

Habitat. — Kino Osima (Japan), A. Adams.

Challenger Specimens. — Living.

Station 175, August 12, 1874 ; Fiji to Kaine Island ; lat. 19° 2' S., long. 177° 10' E.

Near Station 206, January 9, 1875 ; China Sea; about lat. 17° 54' N.; long. 117° 14' E.

Station 216a, February 16, 1875; North of New Guinea; lat. 2° 56' N., long. 134° 11' E.

2. Agadina gouldi, A. Adams.

1867. Agadina gouldi, A. Adams, Description of New Species of Shells from Japan, Proc.

Zool. Soc. Lond., 1867, p. 309, pi. xix. fig. 22.

Shell smooth, helicoid, formed of three and a half bulging and rapidly ascending whorls ; spire not projecting above the last turn ; oblique aperture with margins slightly expanded ; umbilicus very narrow.

REPORT ON THE PTEROPODA.

39

Dimensions. — 1’5 mm. in diameter.

Operculum and animal unknown, but almost certainly like those of the two other species here enumerated.

Habitat. — Kino Osirna (Japan), A. Adams.

#3. Agadina, n. sp. (PL I. figs. 15, 16).

Shell smooth, globular; spire short, but projecting beyond the last whorl; three bulging whorls, overlapping, and somewhat obliquely twisted ; aperture rounded, oblique, with margins slightly expanded ; umbilicus almost suppressed, covered by the last turn, which exhibits a keeled projection over this spot.

Operculum horny, circular, multispiral, with four and a half whorls, gradually increasing in a left-handed spiral ; the surface of insertion very large.

Animal. — Without fins, resembling that of Agadina stimpsoni, but with the lobes of the velum more pointed, and the foot more elongated anteriorly.

Challenger Specimens. — I. Living.

Station 175, August 12, 1874 ; Fiji to Raine Island ; lat. 19° 2' S., long. 1 77° 10' E.

Station 216a, February 16, 1875 ; north of New Guinea; lat. 2° 56' N., long. 134° 11' E.

II. Deposit shells.

Station 120, September 9, 1873; off the coast of South America, between Pernam- buco and Bahia; lat. 8° 37' S., long. 34° 28' W.; depth, 675 fathoms; bottom, red mud.

Since this form, like the two before it, is only the larval form of some Gastropod, there is no occasion to give it a specific title.

It is evident that these species cannot be ranked among the Pteropods. The absence of fins, the presence of a four-lobed velum when the shell has already three whorls on its spire, the presence of a foot with a creeping surface, are facts sufficient to demonstrate that we have here to deal with pelagic larvae of streptoneural Gastropods.

This shows very distinctly the dangers of elaborating a zoological system without due regard to comparative anatomy.

Woodwards1 statement that the true Limacinidae may be distinguished by their left-handed twisting “ from the fry of Atlanta, Carinaria and most other Gastropods ” is thus quite inexact.

What enables one always to distinguish the Limacinidae from the larvae of Gastro-

1 Manual of the Mollusca, 1856, p. 207.

40

THE TOY AGE OF H.M.S. CHALLENGER.

pods, known by the title Agadina, even when the animals themselves are not known, is the horny, perfectly circular operculum of the latter (glassy in the Limacinidse). In the operculum of Agadina, furthermore, the coils of the spire have a left-handed twist, and increase slowly, so that the nucleus of the spiral is much larger than in the Limacinidse. The external surface is also concave ; the aperture is obliquely rounded, with margins somewhat expanded, slightly thickened, and united, i.e., the lip and the columellar margin are continuous by means of a small callus on the latter, which is absent in the Limacinidse.

But to what streptoneural Gastropods do these larval “Agadina” forms belong? The marine left-handed Gastropods are not, indeed, very numerous. But it must be remembered that some Gastropods, with right-handed spirals, have their initial portion or nucleus twisted to the left. This is not improbably the case with the larval forms in question, for there the left-handed twisting of the operculum in all likelihood corre- sponds to a right-handed twisting of the shell.

I. To the group “Agadina” I also refer Atlanta rotundata, d’Orbigny,1 which Souleyet regarded as a variety of Limacina lesueuri (his Spirialis ventricosa). The shell is discoidal and flattened ; the spire in no way projects beyond the last coil ; the mouth is rounded, and broader than high, with slightly thickened margins. The operculum figured by d’Orbigny appears concentric, but as the objects are small and difficult to define, it seems to me more likely that the operculum is multispiral, as in the other forms of “Agadina.”

D’Orbigny ’s specimens were obtained in the Pacific Ocean, 36° S., 38° W. This form has only been chronicled on one other occasion, by Marrat,2 on a voyage from South America to Liverpool. His specimens are deposited in the Liverpool Museum.

II. In closing this appendix to the family Limacinidse it is necessary to note that the “ Agadina ” forms are not the only left-handed larvae of Gastropods which have been taken for Pteropods. The same is true of Limacina turritelloides, Boas,3 the empty shells of which I found in the Challenger collection (Station 216a, north of New Guinea). By every one familiar with the classification of Gastropods, this form would be at once recognised as a young left-handed Cerithium ( Triforis ), nor have I any doubt that this Limacina turritelloides is identical with the form which Craven has described under the title Sinusigera perversa} Like Triforis, this exhibited a multispiral operculum, with right-handed twisting. Craven has, in fact, subsequently acknowledged 5 that his Sinusigera perversa (from the Indian Ocean) is only a pullus of Triforis.

1 Voyage dans l’Amerique meridionale, t. v. p. 175, pi. xii. figs. 20-24.

2 On a collection of Pteropods and Heteropods, Ann. and Mag. Nat. Hist., ser. 4, vol. ii. p. 229.

3 Spolia atlantica, p. 49, pi. iii. fig. 35.

4 Monographie du genre Sinusigera, Ann. Soc. Malacol. Belg., t. xii. p. 112, pi. iii, fig. 4.

5 Note sur le genre Sinusigera, Ann. Soc. Malacol. Belg., t. xviii. p. xxvi.

REPORT ON THE PTEROPODA.

41

Family II. Cavoliniida

1841. Hyalidc e, d’Orbigny, Mollusques de Cuba, t. i. p. 70.

1842. Cavolinidse, d’Orbigny, Paleontologie frai^aise, Terrains ere faces, t. ii. p. 4.

1842. Cleodoridse, Gray, Synopsis of the Contents of the British Museum, p. 92.

1869. Cliidse, Jeffreys, British Conchology, vol. v. p. 118 (non Woodward, 1856).

1875. Orthoconques, Fol, Sur le developpement des Pteropodes, Archives d. Zool. Exper., ser. 1, t. iv. p. 177.

incl. Cuvieridx, Gray, 1842 = Tripteridx, Gray, 1850.

Characters. — Shell external, calcareous, inoperculated, bilaterally • symmetrical, not rolled up in a spiral, but at its apex often dorsally recurved. Animal with its pallial cavity ventral, and its columellar muscle dorsal ; the anus situated on the left.

Description. — The shell has a variable form, which may always be referred to a hollow cone, more or less modified, flattened dorso-ventrally or circular in section. The apex is quite straight, recurved or truncated ; the mouth broad or narrow ; with longi- tudinal or transverse ribs, &c. The initial portion of the shell is generally distinct from the rest, and represents the embryonic shell.

The animal may be entirely retracted within the shell. The form of the fins and of the posterior lobe of the foot varies considerably. The mouth, the lips, and the tentacles resemble those of the Limacinidae (except Peraclis ).

In regard to the classification, as in the Limacinidae, we find a large number of genera established by too zealous conchologists for the reception of the species be- longing to this family. Abstracting genera based on Tertiary fossils, we find seventeen different generic titles applied to living Cavoliniidae. These are enumerated in alpha- betical order : —

Archonta, Montfort, 1810.

Balantium, Benson, 1837.

Carolina, Abildgaard, 1791 ( non

Bruguiere, 1792).

Cleodora, Peron and Lesueur, 1810.

Clio, Linne, 1767 ( non Muller, 1776).

Creseis, Bang, 1828.

Cuvieria, Bang, 1827 (non Peron,

1807).

Cuvierinct, Boas, 1886.

Diacria, Gray, 1842.

Of these seventeen titles : —

1. Three alone ought to be preserved as applicable to well-established genera —

(1) Clio; (2) Cuvierina; (3) Cavolinia.

(zool. chall. EXP. PART LXV. 1887.)

Hyalsea, Lamarck, 1801.

Hyalocylis, Fol, 1875.

Orhignyia, Adams, 1859.

Pleuropus, Eschscholtz, 1825.

Rheda, Humphreys, 1797.

Styliola, Lesueur, 1825.

Triclci, Oken, 1815 ( non Betzius,

1788).

Triptera, Auctorum (non Quoy and Gaimard, 1824).

Ttt 6

42

THE VOYAGE OF H.M.S. CHALLENGER.

2. Three designate well-marked subgeneric divisions of the genus Clio —

(1) Creseis ; (2) Hyalocylix ; (3) Styliola.

3. One represents the young state of some Cavolinia : Pleuropus.

4. Finally, the ten remaining titles may be preserved as synonyms of the three genera —

Balantium,

Cleodora,

Cuvieria,

Triptera,

= Clio .

= Cuvierina .

Arehonta,

Diacria,

Hyalsea,

Orbignyia,

Rheda,

Tricla,

I

= Cavolinia.

For the distinctive characters of the three genera Clio, Cuvierina, and Cavolinia, I refer to the synoptic table of genera (p. 8).

Clio,1 Linne.

1756. Clio, Browne, The Civil and Natural History of Jamaica, p. 386.

1767. Clio, Linne, Systema naturse, ed. 12, t. 1, pt. 2, p. 1094 ( non O. F. Muller, 1776).

1810. Cleodora, Peron and Lesueur, Histoire de la famille des Mollusques Pteropodes, Ann. Mus.

Hist. Nat. Paris, t. xv. p. 66.

1825. Styliola, Lesueur, MS., in de Blainville, Manuel de Malacologie, p. 655.

1828. Creseis, Rang, Notice sur quelques Mollusques nouveaux appartenant au genre Cleodora, et 4tablissement et monographie du sous-genre Creseis, Ann. d. Sci. Nat., s4r. 1, t. xiii, p. 302.

1837. Balantium, Benson, Notice on Balantium, a Genus of the Pteropodous Mollusca, Journ. Asiat. Soc. Bengal, vol. vi. p. 151.

1875. Hyalocylis, Fol, Sur le developpement de Pteropodes, Archives d. Zool. Exper., t. iv. p. 177.

To the Thecosomata which I have united in this genus several generic titles have been applied, as may be seen from the synonyms.

Besides these generic titles, we have to note a considerable number of specific designations, of which only a very small fraction can be retained as applicable to really existing species of the genus Clio.

After abstracting all the so-called forms of Clio which are really Gymnosomata (see the first part of this Report),2 there remains the following formidable list of specific titles attributed to living species. A certain number of extant species are also

1 Mythological name.

2 Zool. Chall. Exped., part lviii. pp. 44, 45.

REPORT ON THE PTEROPODA.

43

found in the most recent Tertiary deposits, and have received other titles in that connection.

Creseis acicula, Ransr.

Creseis cicus, Eschscholtz.

Cleodorci anclrese, Boas.

Hycdsea australis , d’Orbigny.

Cleodora balantium, Rang.

Balantium bicarinatum, Benson. Cleodora brownii , de Blainville.

Creseis caligula, Eschscholtz.

Clio caudata, Linne.

Cleodora chaptalii, Souleyet.

Cleodora chierchise , Boas.

Creseis clava, Rang.

Creseis compressa, Eschscholtz. Cleodora compressa, Souleyet.

Creseis conica, Eschscholtz.

Creseis conoidea, A. Costa.

Hyalsea corniformis, d’Orbigny.

Creseis cornucopise, Eschscholtz. Cleodora curvata, Souleyet.

Hyalsea cuspidata, Bose.

Clio depressa, Gray.

Cleodora exaeuta, Gould.

Cleodora falcata, Gould.

Cleodora falcata, Pfeffer.

Cleodora jlexa, Pfeffer.

Cleodora injlata, Souleyet.

Cleodora lamartinieri, Rang.

Hyalsea lanceolata, Lesueur.

Creseis zonata,

Cleodora lessonii, Rang.

Cleodora lobata, Sowerby.

Cleodora martensii, Pfeffer.

Creseis monotis, Troschel.

Cleodora munda, Gould.

Cleodora obtusa, Quoy and Gaimard. Cleodora occidentalis, Dali.

Clio pellucidum, Gray,

Creseis phseostoma, Troschel.

Cleodora placida, Gould.

Balantium politum, Craven, MS. Cleodora pygmsea. Boas.

Clio pyramidata, Linne.

Cleodora quadrispinosa, Rang. Styliola recta, Lesueur.

Balantium recurvum, Benson.

Clio rugosum, Gray.

Creseis rugulosd, Cantraine.

Creseis spinifera, Rang.

Creseis striata. Rang.

Creseis striata, Delle Chiaje. Cleodora subula, Quoy and Gaimard. Cleodora sulcata, Pfeffer.

Hyalsea tricuspidata, Bowdich. Cleodora trifilis, Troschel.

Creseis unguis, Eschscholtz.

Creseis virgula, Rang.

Styliola vitrea, Yerrill.

,, Delle Chiaje.

These fifty-seven names may be classified as follows : —

1. One may be discarded as not referring to a Pteropod, viz., Creseis rugulosa, Cantraine,1 which is really a Gastropod of the genus Csecum.

2. One refers to the adult stage of another genus of Thecosomatous Pteropods, viz., Cleodora obtusa, Quoy and Gaimard, which is probably the same as Cuvierina columnella.

1 Malacologie Mediterraneenne et littorale, Mem. Acad. d. Sci. Bruxelles, t. xiii. p. 32.

44 THE VOYAGE OF H.M.S. CHALLENGER.

3. Seven names refer to young stages of the Thecosomata of the genus Cavolinia, viz. : —

Cleodora compressa, Souleyet = Cavolinia trispinosa.

Cleodora curvata, Souleyet = Cavolinia uncinata .

Clio depressa, Gray = Cleodora compressa, Souleyet = Cavolinia trispinosa. Clio pellucidum, Gray = Pleuropus pellucidus, Eschscholtz = Cavolinia injlexa. Balantium rugosum , Gray =Hyalaea rugosa, d’Orbigny = Cavolinia gibbosa. Cleodora pygmsea, Boas = Cavolinia quadridentata.

Cleodora trijilis, Troschel = Cavolinia > sp.

The attentive study of the forms designated by the remaining specific titles shows that thirty -three of these ought to be discarded, and considered only as synonyms of

the fourteen remaining species.

Creseis acus, Eschscholtz, Balantium bicarinatum, Benson, Cleodora brownii, de Blainville, Creseis caligula, Eschscholtz, Clio caudata, Linne, .

Creseis clava, Rang,

Creseis compressa, Eschscholtz, . Creseis conoidea, 0. Costa, Hyalsea corniformis, d’Orbigny, Creseis cornucopise, Eschscholtz, Cleodora exacuta, Gould, Cleodora falcata, Gould, Cleodora falcata, Pfeffer, Cleodora flexa, Pfeffer,

Cleodora inflata, Souleyet, Cleodora lamartinieri, Rang, . Hyalsea lanceolata, Lesueur, Cleodora lessoni, Rang,

Cleodora lobata, Sowerby, Cleodora martensii, Pfeffer, Creseis monotis, Troschel, Cleodora munda, Gould,

Creseis phseostoma, Troschel, Creseis placida, Gould,

Cleodora quadrispinosa, Rang, Styliola recta, Lesueur,

= Creseis acicula, Rang.

= Cleodora balantium, Rang.

= Clio pyramidata, Linne.

= Creseis virgula, Rang.

= f Clio pyramidata, Linne.

= Creseis acicula, Rang.

= Creseis striata, Rang.

= Creseis conica, Eschscholtz.

= Creseis virgula, Rang.

= Creseis virgula, Rang.

= Clio pyramidata, Linne.

= Creseis virgula, Rang.

= Balantium politum, Craven, MS.

= Creseis virgula, Rang.

= Cleodora balantium, Rang (young). = Clio pyramidata, Linne.

= Clio pyramidata, Linne.

= Ilyalsea cuspidata, Bose.

= Clio pyramidata, Linne.

= Clio pyramidata, Linne.

= Creseis striata, Rang.

= Creseis virgula, Rang.

= Creseis striata, Rang.

= Creseis virgula, Rang.

= Hyalsea cuspidata, Bose.

= Cleodora subula, Quoy and Gaimard.

REPORT ON THE PTEROPODA.

45

Bcdantium recurvum, Benson, . Creseis spinifera, Bang, Cleodora striata, Delle Chiaje, . Hyalsea tricuspidata, Bowdicli, Creseis unguis, Eschscholtz, Styliola vitrea, Terrill,

Creseis zonata, Delle Chiaje,

The genus Clio thus includes fourteen among the spoils of the Challenger.

Creseis virgula, Bang.

Creseis acicula, Bang.

Creseis conica , Eschscholtz.

Cleodora chierchiae, Boas.

Creseis striata, Bang.

Cleodora subula, Quoy and Gaimard. Hyalsea i australis, d’Orbigny.

= Cleodora balantium, Bang.

= Cleodora subula, Quoy and Gaimard.

= Creseis conica, Eschscholtz.

= Hyalsea cuspidata, Bose.

= Creseis virgula, Bang.

= Creseis conica, Eschscholtz.

= Creseis striata, Bang.

real species, of which eleven are included

Cleodora sulcata, Pfeffer.

Cleodora chaptalii, Souleyet.

Cleodora bcdantium, Bang. Bcdantium politum, Craven, MS. Cleodora andrese, Boas.

Clio pyramidata, Linne.1 Hyalsea cuspidata, Bose.

This genus is thus the richest of the Thecosomata, and indeed of the entire group of Pteropods. It is also that which exhibits the greatest variety of forms. It may wrell be asked whether all the species should be ranged in uniform succession in a homogeneous series, or whether further classification is not possible.

Bang, Philippi, Souleyet, Gould, Pfeffer, Boas, &e., are of opinion that all the species ought to bear the same generic title, and the anatomical researches of Souleyet have shown that the structure is nearly the same in the different forms examined.

On the other hand, the conchologists who are never afraid of a multiplied of names generally divide into three or four genera the series of forms which we comprise under the title Clio.

But the attempt towards classification most worthy of attention is certainly that of Fol,2 who bases his arrangement on the ontogenetic development of Mediterranean forms.

Fol divides the living species of Clio into the four following genera : —

Hyalocylis, Fol ; type Creseis striata, Bang.

Styliola, Lesueur ; type Cleodora subula, Quoy and Gaimard.

Cleodora, Peron and Lesueur ; type Clio pyramidata, Linne.

Creseis, Bang ; type Creseis acicula, Bang.

1 Cleodora occulentalis, Dali, appears to be nearly related to Clio pyramidata. From an unpublished figure which Mr. Dali has been good enough to send me, it possesses between each fin and the posterior lobe of the foot a conical tentacle, which is not found in Clio pyramidata ; but as I have not been able to examine specimens of “ Cleodora occi- dentalis ” I cannot give a decided opinion on this question.

2 Sur le d6veloppement des Mollusques Pteropodes, Archives d. Zool. Expdr., ser. 1, t. iv. pp. 177, 178.

46

THE VOYAGE OF H.M.S. CHALLENGER.

This classification has been adopted in Fischer’s1 Manual of Conchology, and in part also in that of Try on. 2

It is however necessary to remark that Fol distributes these four genera in a manner altogether peculiar, separating most of the species from the group at present under discussion. Thus in our family of Cavoliniidse (his Orthoconques) he distinguishes, ab- stracting the genus Cuvierina, three subgroups, — Hyaleacees, Styliolacees, and Creseidees. Hyalocylix is referred to the first, along with the Cavolinia forms. Styliola and Cleodora are included in the Styliolacees. Creseis is placed among the Creseidees.

I cannot admit that these different forms are separated in this way, or in any way equally deep and trenchant.

Fol’s distinctions, which are based exclusively on embryonic characters, form an insufficient foundation for the classification of the adults. For it must be noted that the forms in question are pelagic larvae in which, as Fritz Muller long ago remarked,3 true genetic characters are mingled with those which are merely adaptive, and provisionally acquired for the free, independent, pelagic larval life.

On the other hand, the different forms of Clio exhibit a type of structure which unites them in one and distinguishes them from the other Thecosomata, and especially from the “Hyaleacees” of Fol (among which the “ Cleodora ” forms are certainly more nearly allied than the Hyalocylix).

Nevertheless, it cannot be denied that among the species which I have united within the genus Clio there are several distinct types, separated not only by the embryonic differences on which Fobs classification is based, but also by certain structural features, which will be discussed in the anatomical portion of this Report. Yet, at the same time, I maintain that these distinctions are not of sufficient import to justify the establishment of separate genera.

I therefore propose to consider the different types above referred to as subgenera of Clio, and since these subgeneric divisions correspond approximately to the genera recognised by Fol, I shall preserve as designations of these subgeneric sections the four titles which Fol has used, viz., Creseis, Hyalocylix, Styliola, Clio ( = Cleodora). As to Balantium, I do not find that it exhibits any characters which would warrant its being- separated from the subgenus Clio ( = Cleodora), s. str.

Within these four sections, the species known to be genuine are distributed in the following fashion : —

1. Subgenus Creseis.

Creseis virgula, Rang. Creseis acicula, Rang.

Creseis conica, Eschscholtz. Cleodora chierchise, Boas.

1 Manuel de Conchyliologie, pp. 435-437. 2 Structural and Systematic Concliology, vol. ii. pp. 90, 91.

3 Facts and Arguments for Darwin, p. 114.

REPORT ON THE PTEROPODA.

47

2. Subgenus Hyalocylix. Creseis striata, Rang.

3. Subgenus Styliola. Cleodora subula, Quoy and Gaimard.

4. Subgenus Clio, s. str.

Balantium politum, Craven, MS. Cleodora andrese, Boas.

Cleodora balantium, Rang.

Hylasa australis, d’Orbigny. Cleodora sulcata, Pfeffer. Clio pyramidata, Linne.

Hyalsea cuspidata, Bose.

The four sections may be distinguished as follows : —

I. Shell without lateral keels.

1. Shell without dorsal longitudinal groove.

A. Shell with a circular section, . . . .1. Creseis.

B. Shell flattened dorso-ventrally, with transverse grooves over

its entire length, . . . . .2. Hyalocylix.

2. Shell with a dorsal longitudinal groove, . . . .3. Styliola.

II. Shell with lateral keels, . . . . . . .4. Clio, including Balantium.

Subgenus Creseis,1 Rang (s. str.).

1828. Creseis, Rang, Notice sur quelques Mollusques nouveaux appartenant au genre Cleodora, &c., Ann. d. Sci. Nat., s6r. 1, t. xiii. p. 302.

Styliola, Auctorum, non Lesueur.

Characters and Description. — Shell elongated, of conical form, with a circular transverse section, with a smooth surface on its initial portion at least, with the embryonic portion not marked off by a deep constriction, with a rounded apex.

Animal with the left tentacle very rudimentary, the fin exhibiting a small narrow projecting lobe on the proximal half of the dorsal (anterior) margin, the opening of the mantle as broad as that of the shell.

1 Mythological name.

48

THE YOYAGE OE H.M.S. CHALLENGER.

Key to the Species.

I. Shell entirely destitute of transverse grooves.

1. Shell at its initial portion of a dark brown colour.

A. Shell with a very marked and somewhat abrupt dorsal curve, and with

the transverse diameter increasing rapidly at the point of curvature, 1. Clio virgula.

B. Shell with a slight curvature, and with, the transverse diameter

increasing uniformly, . . . . . .2. Clio conica.

2. Shell straight, much elongated, with the initial extremity of a whitish

colour, . . . . . . . . .3. Clio acicula.

II. Shell with transverse grooves all over its broader portion, . . . .4. Clio chierchix.

#1. Clio ( Creseis ) virgula (Rang).

1828. Creseis virgula, Rang, Notice sur quelques Mollusques nouveaux du genre Cleodora, &c.,

Ann. d. Sci. Nat., ser. 1, t. xiii. p. 316, pi. xvii. fig. 2.

1829. Creseis unguis, Eschscholtz, Zoologischer Atlas, Heft iii. p. 17, pi. xv. fig. 4.

1829. Creseis cornucopix, Eschscholtz, Ibid., p. 17, pL xv. fig. 5.

1829. Creseis caligula, Eschscholtz, Ibid., p. 18, pi. xv. fig. 6.

1836. Hyalxa corniformis, d’Orbigny, Voyage dans l’Am4rique meridionale, t. v. p. 120, pi. viii.

figs. 20-23.

1850. Styliola virgula, Gray, Catalogue of the Mollusca in the Collection of the British

Museum, pt. ii., Pteropoda, p. 17.

1850. Styliola corniformis, Gray, Ibid., p. 18.

1852. Cleodora virgula, Souleyet, Voyage de la Bonite, Zoologie, t. ii. p. 196, pi. viii.

figs. 18-25.

1852. Cleodora munda, Gould, The Mollusca and Shells of the U.S. Exploring Expedition,

p. 489, pi. Ii. fig. 607.

1852. Cleodora placida, Gould, Ibid., p. 489, pi. Ii. fig. 606.

1852. Cleodora falcata, Gould, Ibid., p. 490, pi. Ii. fig. 608.

1879. Cleodora flexa, Pfeffer, Bericht fiber die von S. M. Schiff “Gazelle” und Dr. Jagor gesammelten Pteropoden, Monatsher. d. k. preuss. Akad. d. Wiss. Berlin, 1879, p. 241, figs. 15, 16.

For description and figures I refer to Souleyet, loc. cit. (see the synonymy above). Habitat. — Atlantic Ocean, from 41° 25' N. (Verrill) to 35° 10' S. (Boas), both towards the new and the old world.

Indian Ocean ; from the Gulf of Bengal to 29° S., especially towards the west (south- east of Arabia, Blanford) to 65° E.

Pacific Ocean: eastern portion, from 35° N., about the Bay of Yedo (“Galathea” Expedition), to 32° S., New South Wales (British Museum), China Sea (“Galathea” Expedition), Coral Sea (Pfeffer); central portion, from 24° N. (“ Vettor Pisani” Expedition) to 30° S. (Knocker); North-east Pacific (Gould as “Cleodora falcata”); South-east Pacific, Juan Fernandez Island (d’Orbigny).

i

REPORT ON THE PTEROPODA.

49

Challenger Specimens. — I. Living specimens.

Station 106, August 25, 1873; St. Vincent (Cape Verde) to St. Paul’s Rock; lat. 1" 47' N., long. 24° 26' W.

Between Stations 162 and 163, April 3, 1874 ; Melbourne to Sydney, lat. 38° 7' S., long. 149° 18' E.

Station 164a, June 13, 1874 ; off Sydney ; lat. 34° 9' S., long. 151° 55' E.

Station 181, August 25, 1874 ; Fiji to Eaine Island; lat. 13° 50' S., long. 151° 49' E.

Station 209, January 22, 1875; Manila to Samboangan ; lat. 10° 14' N., long. 123° 54' E.

On February 6, 1875 ; at Samboangan; lat. 6° 40' N., long. 122° 57' E.

Station 216a, February 16, 1875 ; north of New Guinea; lat. 2° 56' N.,

long. 134° 11' E.

Between Stations 229 and 230, April 3, 1875; Admiralty Islands to Yokohama; lat. 24" 49' N., long. 138° 34' E.

Station 230, April 5, 1875; Admiralty Islands to Yokohama; lat. 26° 29' N., long. 137° 57' E.

Between Stations 264 and 265, August 24, 1875; Sandwich Islands to Tahiti; lat. 13° 15' N., long. 152° 2' W.

Station 299, December 14, 1875; Valparaiso to Gulf of Penas; lat. 33° 31' S., long. 74° 43' W.

Station 348, April 9, 1876; Ascension Island to St. Vincent (Cape Verde); lat. 3° 10' N., long. 14° 51' W.

On April 26, 1876 ; off St. Vincent; lat. 16° 49' N., long. 25° 14' W.

On April 29, 1876 ; off St. Vincent ; lat. 18° 8' N., long. 30° 5' W.

II. Deposit shells.

Station 23, March 15, 1873 ; off Sombrero Island ; lat. 18° 24' N., long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

Station 24, March 25, 1873 ; off Culebra Island ; lat. 18° 38' 30" N., long. 65 5'30"W.; depth, 390 fathoms ; bottom, Pteropod ooze.

Station 33, April 4, 1873 ; off Bermuda; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

Station 120, September 9, 1873 ; off the coast of South America, between Pernam- buco and Bahia; lat. 8° 37' S., long. 34° 28' W.; depth, 675 fathoms; bottom, red mud.

Station 185, August 31, 1874 ; off Raine Island; lat. 11° 35' 25" S., long. 144° 2' 0" E.; depth, 135 fathoms; bottom, coral sand.

Station 219, March 10, 1875; Admiralty Islands to Yokohama; lat. 1° 54' 0" S., ong. 146° 39' 40" E.; depth, 150 fathoms; bottom, coral mud.

(ZOOL. CHALL. EXP. PART LXV. 1887.)

Ttt 7

50

THE VOYAGE OF H.M.S. CHALLENGER.

*2. Clio ( Creseis ) conica (Eschscholtz) (PL II. figs. 1, 2).

1829. Creseis conica, Eschscholtz, Zoologischer Atlas, Heft iii. p. 17, pi. xv. fig. 3.

1830. Creseis striata, Delle Chiaje, Memorie sulla storia e notomia degli animali senza vertebre,

pi. lxxxii. fig. 12.

1869. Creseis conica, A. Costa, Pteropodi del golfo di Napoli, Rendiconto d. reale Accad. d.

Sci. Napoli, 1869, p. 58.

1872. (?) Styliola vitrea, Verrill, Recent Additions to the Molluscan Fauna of New England

and the adjacent waters, &c., Amer. Journ. Sci. and Arts, vol. iii. p. 284, pi. vi. fig. 7.

1873. Creseis conoidea, A. Costa, Pteropodi della Fauna del Regno di Napoli, p. 17, pi. iv.

fig. 6.

Characters and Description. — Shell conical, moderately elongated ; smooth over its entire surface ; a very slight and regular dorsal curvature ; the transverse diameter increasing gently and uniformly ; the posterior extremity of a dark brown colour ; the embryonic portion separated by a well-marked constriction, and thinning off towards the somewhat slender apex (PI. II. fig. 2).

Animal like that of Clio ( Creseis ) virgula, but distinguished at first sight by this marked feature that the mass formed by the stomach and liver is situated much further forward than in the above species. For while in Clio virgula the broad oesophagus is very long, and the mass in question removed from the posterior extremity of the shield (pallial gland) by more than the length of the latter, in Clio conica it is situated imme- diately behind the shield. With this difference there is obviously correlated the abrupt and precocious enlargement of the shell in Clio virgula, and the gentle uniform increase in Clio conica.

Observations. — I. There can be no doubt in regard to the species figured by Eschscholtz. It is not Clio ( Creseis ) acicula, since it is much too short in proportion, and has its posterior extremity of a dark brown colour. It is not Clio ( Creseis ) virgula, since it exhibits neither the abrupt curvature nor the precocious enlargement of diameter exhibited by that form, and since the visceral mass is situated anteriorly. Neither is it Clio ( Styliola ) subula, although Gray 1 and Souleyet 2 so regard it. The absence of a dorsal groove, the colour of the posterior extremity, and the shortness of the posterior lobe of the foot are enough to show that it is not.

The “ Creseis conica ” of Eschscholtz is in fact the species which one finds at Naples, and in all probability that which Delle Chiaje noted under the name of “ Creseis striata.”

A. Costa, thinking he had discovered a new species, described this form as Creseis conica, ignoring the fact that this title had been already used by Eschscholtz. Becoming aware of this, but failing to recognise the identity of the two forms, he changed the name conica to conoidea.

1 Catalogue of the Mollusca in the Collection of the British Museum, pt. ii., Pteropoda, p. 17.

2 Histoire naturelle des Mollusques Pteropodes, p. 55.

REPORT ON THE PTEROPODA.

51

II. The figure given by Eschscholtz has been referred by Gray and by Souleyet (not without hesitation) to Clio mbula ; I have indicated above that this identification is impossible.

On the other hand Boas, who is of opinion 1 that Clio virgula and Clio acicula should be united, figures2 under the title “ Cleodom acicula” a specimen which undoubtedly belongs to the species under discussion. At the same time he designates as “ Cleodora acicula ” 3 the specimens of the “ Vettor Pisani ” Expedition, which also resemble Clio conicci. The latter is distinguished from Clio acicula not only in the characters of the shell noted above, but also in the conformation of the liver, which agrees with what is found in Clio virgula. Clio conica is beyond dispute more nearly allied to Clio virgula than to Clio acicula.

Dimensions. — Besides being distinguished by certain characters of the shell and of the animal, Clio conica is also marked by its size, which never exceeds 7 mm.

Habitat. — Atlantic Ocean : coast of Brazil (Eschscholtz) ; coasts of North America (if, as I believe, Styliola vitrea = Clio conica ).

Mediterranean : Naples.

Pacific Ocean : eastern portion, 0 N., 84° 40' W. (“Vettor Pisani” Expedition).

Challenger Specimens. — Deposit shells.

Station 219, March 10, 1875; Admiralty Islands to Yokohama; lat. 1° 54' 0" S., long. 146° 39' 40" E.; depth, 150 fathoms; bottom, coral mud.

#3. Clio ( Creseis ) acicula (Rang).

1828. Creseis acicula , Rang, Notice sur quelques Mollusques nouveaux du genre Cleodora, &c., Ann, d. Sci. Nat., ser. 1, t. xiii. p. 318, pL xvii. fig. 6.

1828. Creseis clava, Rang, I lid., p. 317, pi. xvii. fig. 5.

1829. Creseis acus, Eschscholtz, Zoologischer Atlas, Heft iii. p. 17, pi. xv. fig. 2.

1836. Hyalxa aciculata, d’Orhigny, Voyage dans l’Amerique meridionale, t. v. p. 123, pi. viii.

figs. 29-31.

1850. Styliola reda, Gray, Catalogue of the Mollusca in the Collection of the British Museum, pt. ii., Pteropoda, p. 18.

1852. Cleodora acicula , Souleyet, Voyage dela Bonite, Zoologie, t. ii. p. 194, pi. viii. figs. 10-17.

For description and figures, see Souleyet, loc. cit. (in the above list of synonyms). Habitat.— Atlantic Ocean, from 48° N. to the Cape of Good Hope (Pfeffer), and to 40° S. (Knocker). Mediterranean : Naples, &c. Indian Ocean : from the Gulf of Bengal to 29° S. (Boas) ; from Zanzibar (Pfeffer) to near Australia (95 E.).

Pacific Ocean : West, China Sea (Boas) ; Central Pacific, from 10° N. (Knocker) to 23° S. (Pfeffer), and towards 153° W.; Eastern Pacific towards the equator, 88° W. (“Vettor Pisani” Expedition).

1 Spolia atlantica, p. 202.

2 Ibid., pi. vi. fig. 94.

3 Ibid., p. 61.

THE YOYAGE OF H.M.S. CHALLENGER.

52

Challenger Specimens. — I. Living specimens.

Station VIIf., February 2, 1873 ; off Madeira ; lat. 32° 27' 0" N., loug. 16° 40' 30" W.

Station 62, June 18, 1873; Bermuda to Azores; lat. 35° 7' N., long. 52° 32' W.

Station 63, June 19, 1873 ; Bermuda to Azores ; lat. 35° 29' N., long. 50° 53' W.

Station 81, July 13, 1873 ; Azores to Madeira ; lat. 34° iff N., long. 19° 52' W.

Station 164a, June 13, 1874 ; off Sydney; lat. 34° 9' S., long. 151° 55' E.

Station 175, August 12, 1874 ; Fiji to Raine Island; lat. 19° 2' S., long. 177° 10' E.

Station 181, August 25, 1874 ; Fiji to Raine Island ; lat. 13° 50' S., long. 151° 49' E.

Near Station 190, September 13, 1874; south of the Arrou Islands; lat. 8° 18' S., long. 135° 7' E.

Station 200, October 23, 1874; Amboina to Samboangan; lat. 6° 47' N.,

long. 122° 28' E.

Station 201, October 26, 1874; Samboangan to Manila; lat. 7° 3'N., long. 121° 48' E.

Station 209, January 22, 1875; Manila to Samboangan; lat. 10° 14' N.,

long. 123° 54' E.

On February 5, 1875 ; at Samboangan.

On February 6, 1875 ; at Samboangan ; lat. 6° 40' N., long. 122° 57' E.

Station 216a, February 16, 1875 ; north of New Guinea; lat. 2° 56' N.,

long. 134° 11' E.

Station 237, June 17, 1875; Yokohama to Sandwich Islands; lat. 34° 37' N., long. 140° 32' E.

Station 256, July 21, 1875 ; Yokohama to Sandwich Islands; lat. 30° 22' N., long. 154° 56' W.

August — September, 1875; Sandwich to Tahiti.

Between Stations 292 and 293, October 31, 1875; Tahiti to Valparaiso, lat. 38° 50' S., long. 108° 6' W.

Station 323, February 28, 1876 ; Falkland Islands to Rio de la Plata ; lat. 35° 39' S., long. 50° 47' W.

Station 326, March 3, 1876; Rio de Janeiro to Tristan da Cunha; lat. 37° 3' S., long. 44° 17' W.

Station 327, March 4, 1876 ; Rio de Janeiro to Tristan da Cunha; lat. 36° 48' S., long. 42° 45' W.

Station 339, March 23, 1876 ; Tristan da Cunha to Ascension Island; lat. 17° 26' S., long. 13° 52' W.

Station 349, April 10, 1876; Ascension Island to St. Vincent (Cape Verde); lat. 5° 28' N., long. 14° 38' W.

On April 26, 1876 ; off St. Vincent; lat. 16° 49' N., long. 25° 14' W.

On April 29, 1876 ; off St. Vincent ; lat. 18° 8' N., long. 30° 5' W.

Station 353, May 3, 1876 ; St. Vincent to Azores; lat. 26° 21' N., long. 33° 37' W.

REPORT ON THE PTEROPODA.

53

II. Deposit shells.

Station 23, March 15, 1873 ; off Sombrero Island; lat. 18° 24' N., long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

Station 24, March 25, 1873 ; off Culebra Island ; lat. 18° 38' 30" N., long. 65° 5' 30" W.; depth, 390 fathoms ; bottom, Pteropod ooze.

Station 33, April 4, 1873 ; off Bermuda ; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

Station 35c, April 22, 1873 ; off Bermuda ; lat. 32° 15' N., long. 65° 8' W.; depth, 1950 fathoms; bottom, Globigerina ooze.

Station 85, July 19, 1873 ; off Palma Island (Canaries); lat. 28° 42' N., long. 18° 6' W.; depth, 1125 fathoms; bottom, volcanic mud.

Station 120, September 9, 1873 ; off the coast of South America, between Pernam- buco and Bahia; lat. 8° 37' S., long. 34° 28' W.; depth, 675 fathoms; bottom, red mud.

Station 122, September 10, 1873 ; off the coast of South America, between Pernam- buco and Bahia; lat. 9' 5' S., long. 34° 50' W.; depth, 350 fathoms; bottom, red mud.

Station 185, August 31, 1874 ; off Raine Island ; lat. 11° 35' 25" S., long. 144° 2' 0" E.; depth, 135 fathoms; bottom, coral sand.

Station 219, March 10, 1875; Admiralty Islands to Yokohama; lat. 1° 54' 0" S., long. 146’ 39' 40" E.; depth, 150 fathoms ; bottom, coral mud.

Note.

According to Boas, the three preceding species are really identical. Little desirous as I am to multiply the number of species, I cannot admit the accuracy of this identification.

Clio acicula is distinguished from the two other species, not only by some characters of the shell (posterior portion whitish, opaque, instead of being transparent and dark brown), but also by some structural features, and especially by the nature of the liver, which is represented by a much reduced mass of acini, while the pyloric caecum attains very conspicuous development.

It must be allowed that the other two species ( Clio virgula and Clio acicula) are nearer neighbours, but the diagnostic characters which have been noted above make a union of the two species impossible.

4. Clio ( Creseis ) chierchise (Boas).

1886. Cleodora cliiercliix, Boas, Spolia atlantica, p. 62, pi. iii. fig. 39ter.

Characters and Description. — This minute species (2*5 mm. in length) is very distinctly characterised and is readily distinguished from all the other members of the group by the fact that the shell, over about two-thirds of its length, is covered with

54

THE VOYAGE OF H.M.S. CHALLENGER.

transverse grooves, which are closely approximated and equidistant like those of Clio striata. This cannot be regarded as teratological, for this species has been collected in different localities and in great abundance. Nor is it a young stage, for none of the observed specimens exceeded the size indicated. Clio chierchise differs notably from Clio striata in the absence of curvature on the shell, by the form of the embryonic shell, and by the form of the fins.

Habitat. — Different localities near Panama (“ Vettor Pisani” Expedition).

Subgenus Hyalocylix / Fol.

1875. Hyaloeylis, Fol, Sur le developpement des Pteropodes, Archives d. Zool Exper., s4r. 3, t. iv. p. 177.

Creseis (pars), Rang.

Styliola (pars) auctorum (non Lesueur).

Cleodora (pars), Souleyet, Boas, &c.

Characters and Description. — Shell conical, slightly compressed dorso-ventrally (oval transverse section) ; the apex recurved dorsally ; the surface marked with trans- verse grooves from the well-marked constriction defining the embryonic shell on to the aperture.

The animal has a conspicuous left tentacle ; the fin has a marginal non-muscular area, situated towards the dorso-lateral corner ; the posterior lobe of the foot is extremely short ; the aperture of the mantle as large as that of the shell.

This “ subgenus ” includes only a single species.

#5. Clio (Hyalocylix) striata (Rang) (PI. II. fig. 3).

1828. Creseis striata, Rang, Notice sur quelques Mollusques appartenant au genre Cleodora, &c.,

Ann. d. Sci. Nat., ser. 1, t. xiii. p. 315, pi. xv. fig. 7.

1829. Creseis compressa, Eschscholtz, Zoologischer Atlas, Heft iii. p. 17, pi. xv. fig. 7.

1830. Creseis zonata, Delle Chiaje, Memorie sulla storia e notomia degli animali senza vertebre,

pi. lxxxii. fig. 9.

1850. Styliola striata, Gray, Catalogue of the Mollusca in the Collection of the British Museum, pt. ii., Pteropoda, p. 18.

1854. Creseis phxostoma, Troschel, Beitrage zur Kenntniss der Pteropoden, Archiv f. Natur-

gesch., 1854, p. 206, pi. viii. figs. 5-7.

For description and figures, I refer to Souleyet, Voyage de la Bonite, Zoologie, t. ii. p. 191, pi. viii. figs. 1-4.

Observations. — I. In the preserved specimens the embryonic shell is almost always deciduous, so that this portion is hardly known. Fol alone2 has figured it from young specimens. Having observed it on the living adults, I am able to give a more definite

1 From vctkins, glassy, x.vkt%, cup.

2 Sur le developpement des Ptdropodes, Archives d. Zool. Exper., s6r. 1, t. iv. figs. 2, 4.

REPORT ON THE PTEROPODA.

55

representation (PL II. fig. 3). This embryonic portion has a rounded apex, it is distinctly expanded, and separated by a well-marked constriction from the rest of the shell. It seems most closely to resemble that of Clio australis.

II. Troschel has figured,1 under the name of Creseis monotis, a small Thecosomatous form “without shell.” This seems to me to be only a bad representation of a Clio striata. I have often observed living specimens of this species which had lost their shell.

III. The name “ Creseis fasciata,” Delle Chiaje, which is cited by several authors, is the Italian title given to this form by Delle Chiaje. The Latin designation, which the same authority uses, is Creseis zonata (see the synonyms above).

Habitat. — Atlantic Ocean : from 36^ 30' N. to 40° S., especially towards the Old World. Mediterranean, on the coasts of Europe and Africa.

Indian Ocean : from the Gulf of Bengal to 25° S. (Boas). Red Sea (Issel).

Pacific Ocean : China Sea (Boas) ; New South Wales (British Museum) ; Equatorial Pacific, 147° 48' W. (Knocker); Chili (“ Vettor Pisani” Expedition).

Challenger Specimens. — I. Living specimens.

Station 175, August 12, 1874 ; Fiji to Raine Island ; lat. 19° 2' S., long. 177° 10' E.

Station 181, August 25, 1874; Fiji to Raine Island; lat. 13° 50' S., long. 151° 49' E.

Station 200, October 23, 1874; Amboina to Samboangan ; lat. 6° 47' N., long. 122° 28' E.

Station 201, October 26, 1874; Samboangan to Manila; lat. 7° 3' N., long. 121° 48' K

Station 230, April 5, 1875; Admiralty Islands to Yokohama; lat. 26° 29' N., long. 137° 57' E.

Between Stations 247 and 248, July 4, 1875; Yokohama to Sandwich Islands; lat. 36° 42' N., long. 179° 50' W.

Station 254, July 17, 1875; Yokohama to Sandwich Islands; lat. 35° 13' N., long. 154° 43' W.

Station 282, October 7, 1875 ; Tahiti to Valparaiso ; lat. 23° 46' S., long. 149° 59' W.

Station 337, March 19, 1876 ; Tristan da Cunha to Ascension Island; lat. 24° 38' S., long. 13° 36' W.

On May 12, 1876 ; off the Azores ; lat. 42° 52' N., long. 28° 54' W.

II. Deposit shells.

Station 24, March 25, 1873 ; off Culebra Island ; lat. 18° 38' 30" K, long. 65° 5' 30" W.; depth, 390 fathoms; bottom, Pteropod ooze.

Station 33, April 4, 1873 ; off Bermuda ; lat. 32 21' 30" N., long. 64 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

1 Beitrage zur Kenntniss der Pteropoden, Archivf. Naturgescli., 1854, Bd. i. p. 288, pi. viii. figs. 8, 9.

56

THE VOYAGE OF H.M.S. CHALLENGED.

Station 85, July 19, 1873 ; off Palma Island (Canaries); lat. 28° 42' N., long. 18° 6' W.; depth, 1125 fathoms; bottom, volcanic mud.

Station 120, September 9, 1873; off the coast of South America, between Pernam- buco and Bahia; lat. 8° 37' S., long. 34° 28' W.; depth, 675 fathoms; bottom, red mud.

Station 185, August 31, 1874 ; off Paine Island; lat. 11° 35' 25" S., long. 144° 2' 0" E.; depth, 135 fathoms; bottom, coral sand.

Station 219, March 10, 1875; Admiralty Islands to Yokohama; lat. 1° 54' 0" S., long. 146° 39' 40" E.; depth, 150 fathoms ; bottom, coral mud.

Subgenus Styliola,1 Lesueur.

1825. Styliola, Lesueur, in de Blainville, Manuel de Malacologie, p. 655.

Characters and Description. — Shell conical, straight, considerably elongated ; the surface smooth, with a dorsal groove not parallel to the axis of the shell, but slightly oblique, turning from left to right, with only the anterior extremity (which ends in a rostrum) in the median line ; the embryonic portion only vaguely separated from the rest of the shell, and ending in a pointed apex.

The animal with the two tentacles distinctly visible ; the transparent, non-muscular, marginal area of the fin situated towards the middle of the lateral margin ; the posterior lobe of the foot is long.

Observation. — The name Styliola, first used in 1825 by Lesueur in the Manuel de Malacologie of de Blainville, has been regarded by English and American conchologists as synonymous with the later title, Creseis, Rang. This opinion is based, however, on a misinterpretation of the typical species, Styliola recta, Lesueur ( sine descriptione), which has been taken by these authors for Clio acicula. But the descriptions given of the genus Styliola enable one to infer that Styliola recta is really Clio subula, and not Clio acicula.

The difference between Styliola (in the usage of Lesueur) and Creseis (s. str.) may be gathered from a comparison of the two descriptions given above. The structural features, as will be shown in the Anatomical Report, go to show that Styliola is much more nearly related to Clio (s. str.) than to Creseis, and on the contrary that the forms included under the latter designation have retained some more archaic characters of the Limacinidse.

This subgeneric section includes only a single species.

1 Diminutive of arvMs, column.

REPOET ON THE PTEROPODA.

57

#6. Clio ( Styliola ) subula (Quoy and Gaimard).

1825. Styliola recta, Lesueur, in de Blainville, Manuel de Malacologie, p. 655 {nomen tantum).

1827. Cleodora subula, Quoy et Gaimard, Observations zoologiques faites a bord de l’Astrolabe,

&c., Ann. d. Sci. Nat., ser. 1, t. x. p. 233, pi. viii. d. figs. 1-3.

1828. Creseis spinifera, Rang, Notice sur quelques Mollusques nouveaux du genre Cleodora,

&c., Ann. d. ScL Nat., ser. 1, t. xiii. p. 313, pi. xvii. fig. 1.

1828. Creseis subula. Rang, Ibid., pi. xviii. fig. 1.

1836. Hyalxa subxda, d’Orbigny, Voyage dans l’Amerique meridionale, t. v. p. 119, pi. viii. figs. 15-19.

1850. Styliola subula, Gray, Catalogue of the Mollusea in the Collection of the British Museum, pt. ii., Pteropoda, p. 17.

1852. Cleodora subulata, Souleyet, Voyage de la Bonite, Zoologie, t. ii. p. 191, pi. viii. figs. 5-9.

For description and figures, see Souleyet ( loc . cit. supra).

Habitat. — Atlantic Ocean; from 41° N. to 25° S. (Pfeffer), towards the coasts both of the Old World and of America (Antilles, &c.); Mediterranean, Naples, &c. The empty shells have been dredged at numerous localities in the Mediterranean (Tunis, &c.).

Indian Ocean; southern portion, from 17° 20' S. to 38° 28' S. (Boas); on the coasts of Africa (Zanzibar, Port Natal), and towards Australia.

Pacific Ocean ; eastern portion, Malay Archipelago (Amboina, New Guinea), east coast of Australia to 32 S. (Pfeffer, Angas); western portion, from 23° N. to 35° S.

Boas has remarked1 the absence of this species below the equator, and notes the same in regard to Cavolinia gibbosa. This has been noticed in regard to other Molluscs, as I have remarked for instance in regard to Lassea rubra.2. It is, however, less explicable in the case of Molluscs which can shift their ground so readily as the Pteropods. But as a matter of fact, Clio subaki is found in the Pacific Ocean both to the south and to the north of the equator.

Challenger Specimens. — I. Living specimens.

Near Station 160, March 15, 1874; off Melbourne ; lat. 39° 45' S., long. 140° 40' E.

Near Station 160, March 16, 1874; off Melbourne ; lat. 39° 22' S., long. 142° 27' E.

Station 164a, June 13, 1874 ; off Sydney; lat. 34° 9' S., long. 151° 55' E.

Station 175, August 12, 1874 ; Fiji to Raine Island; lat. 19° 2' S., long. 1 77° 10' E.

Station 181, August 25, 1874 ; Fiji to Raine Island; lat. 13° 50' S., long. 151° 49' E.

Near Station 230, April 3, 1875; Admiralty Islands to Yokohama; lat. 26° 29' N., long. 138° 34' E.

On April 4, 1875 ; Admiralty Island to Yokohama; lat. 25° 33' N., long. 137° 57' E.

Station 251, July 10, 1875; Yokohama to Sandwich Islands; lat. 37° 37' N., long. 163° 26' W.

Station 254, July 17, 1875 ; Yokohama to Sandwich Islands; lat. 35° 13' N., long. 154° 43' W.

1 Spolia atlantica, p. 66. 2 Sur l’aire de dispersion de Lassea rubra, Bull. Scient. Nord, 1886, p. 235.

(ZOOL. CHALL. EXP. — PART LXV. — 1887.) Ttt 8

58

THE VOYAGE OE H.M.S. CHALLENGER.

Station 256, July 21, 1875 ; Yokohama to Sandwich Islands; lat. 30° 22' N., long. 154° 56' W.

Station 294, November 3, 1875 ; Tahiti to Valparaiso ; lat. 39° 22' S., long. 98° 46' W.

Station 332, March 10, 1876; Rio de Janeiro to Tristan da Cnnha; lat. 37° 29' S., long. 27° 31' W.

On April 28, 1876 ; off St. Vincent; lat. 17° 47' N., long. 28° 28' W.

On May 12, 1876 ; off the Azores ; lat. 42° 52' N., long. 28° 54' W.

II. Deposit shells.

Station VIII., February 12, 1873; off the Canary Islands; lat. 28° 3' 15" N., long. 17° 27' 0" W.; depth, 620 fathoms; bottom, volcanic mud.

Station 3, February 18, 1873; Tenerife to Sombrero Island; lat. 25° 45' N., long. 20° 14' W.; depth, 1525 fathoms; bottom, hard ground.

Station 23, March 15, 1873; off Sombrero Island; lat. 18° 24' N., long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

Station 24, March 25, 1873 ; off Culebra Island; lat. 18° 38' 30" N., long. 65° 5' 30" W.; depth, 390 fathoms; bottom, Pteropod ooze.

Station 33, April 4, 1873; off Bermuda ; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms; bottom, coral mud.

Station 35c, April 22, 1873; off Bermuda; lat. 32° 15' N., long. 65° 8' W.; depth, 1950 fathoms; bottom, G-lobigerina ooze.

Station 75, July 2, 1873 ; off Fayal (Azores); lat. 38° 38' 0" N., long. 28° 28' 30" W.; depth, 450 fathoms ; bottom, volcanic mud.

Station 78, July 10, 1873 ; off the Azores; lat. 37° 26' N., long. 25° 13' W.; depth, 1000 fathoms ; bottom, volcanic mud.

Station 85, July 19, 1873 ; off Palma Island (Canaries); lat. 28° 42' N., long. 18° 6' W.; depth, 1125 fathoms; bottom, volcanic mud.

Station 120, September 9, 1873; off the coast of South America, between Pernam- buco and Bahia; lat. 8° 37' S., long. 34° 28' W. ; depth, 675 fathoms; bottom, red mud.

Station 122, September 10, 1873; off the coast of South America, between Pernam- buco and Bahia ; lat. 9° 5' S., long. 34° 50' W.; depth, 350 fathoms ; bottom, red mud.

Station 164, June 12, 1874; off Sydney; lat. 34° 8' S., long. 152° 0' E.; depth, 950 fathoms ; bottom, green mud.

Station 185, August 31, 1874; off Raine Island; lat. 11° 35' 25" S., long. 144° 2' 0" E.; depth, 135 fathoms; bottom, coral sand.

Station 219, March 10, 1875; Admiralty Islands to Yokohama; lat. 1° 54' 0" S., long. 146° 39' 40" E.; depth, 150 fathoms; bottom, coral mud.

Station 335, March 16, 1876 ; Tristan da Cunha to Ascension Island ; lat. 32° 24' S., long. 13° 5' W.; depth, 1425 fathoms; bottom, Pteropod ooze.

REPOET ON THE PTEROPODA.

59

Subgenus Clio, Linne.

1767. Clio, Linne, Systema Naturae, ed. 12, p. 1094 ( non Muller, 1776).

1810. Cleodora, Peron et Lesueur, Histoire de la Famille des Mollusques Pteropodes, Ann.

Mus. Hist. Nat. Paris, t. xv. p. 66.

1829. Balantium, Anonymous (Children, fide Gray), Journ. Roy. Inst., vol. xv. p. 220.

Characters and Description. — Shell, of a somewhat angular form, colourless, compressed dorso-ventrally, with lateral keels. An anterior transverse section is thus always angular laterally. There is generally a crest or rib extending longitudinally along the back, and usually projecting. The embryonic shell varies in form, but is always definitely separate from the rest.

Animal. — The aperture of the mantle is smaller than the aperture of the shell ; the margins are laterally united for a certain distance, as in Cavolinia ; the simple lateral prolongations of the mantle corresponding to the lateral keels hardly extend beyond the margin of the shell ; the fin has a non-muscular space situated towards the middle of the distal margin ; the left tentacle is always distinctly visible ; there is a triangular dorsal lobe between the two fins, and formed by the union of the two lips ; the anus is situated far in front, near the aperture of the mantle.

Key to the Species.

I. Shell with lateral keels over its entire length.

1. Shell with dorsal ribs very slightly projecting.

A. Shell with a broad posterior portion, ....

B. Shell with a narrow posterior portion, ....

2. Shell with dorsal ribs markedly projecting.

A. Shell with three dorsal ribs, ......

B. Shell with five dorsal ribs, ......

II. Shell with no lateral keels on the posterior portion.

1. Shell without lateral spines.

A. Shell with the lateral margins almost parallel, ....

B. Shell with the lateral margins very divergent.

a. Transverse grooves on the posterior portion, dorsal ribsjnultiple, .

b. No posterior transverse grooves, the dorsal ribs undivided,

2. Shell with lateral spines, .......

Clio andrese. Clio polita.

Clio balantium. Clio chaptali.

Clio australis.

Clio sulcata.

Clio pyramidata. Clio cuspidata.

7. Clio andrese (Boas).

1886. Cleodora andrese, Boas, Spolia atlautica, p. 80, pi. i. fig. 1 , pi. ii. fig. 12.

This species, which closely resembles Clio polita (see below), is distinguished by its greater breadth, especially in the posterior portion, by its two equally bulging faces, by its more marked flattening, by its curvature, especially localised on the posterior

60

THE VOYAGE OF H.M.S. CHALLENGER.

portion, and contrasting with the straight anterior region. This curvature is dorsal over the greater portion of its length, but is slightly ventral towards the apex. The embryonic portion is not separated by a projecting ring from the rest of the shell. The length is also considerable, 20 mm.

Habitat. — South Atlantic Ocean, 33° 30' S., 1° O' W.

#8. Clio polita (Craven, MS.) (PI. II. figs. 4-6).

1880. Clcodora falcata, Pfeifer, Die Pteropoden des Hamburger Museums, Abhandl. Naturwiss.

Ver. Hamburg, P>d. vii. p. 96, pi. vii. fig. 19 (not Gould, 1852).

Balantium politum, Craven, MS. (British Museum).

Characters and Description. — Shell, slender, narrow posteriorly, smooth over its entire surface, more bulging ventrally than dorsally, exhibiting on the former surface four slight longitudinal grooves, but none on the latter. The lateral keels are well- marked, sharp, projecting, parallel to the axis of the shell, more delicate than those of Clio balantium, and not hollow-edged. The dorsal curvature is uniform and continuous. Pfeffer has indeed figured two specimens of this species, one of which exhibits a regular curvature (fig. 196), while the other is much recurved posteriorly (fig. 19a), and has based his description on the latter. But all the specimens which I have seen from the collections of the “Valorous” and the Challenger also resemble fig. 196, which I am therefore warranted in regarding as the normal type. The middle of the lips does not project anteriorly. The embryonic shell has a bulging oval form, rounded on its posterior portion, and separated from the rest of the shell by a well-marked constriction, limited by a small projecting ring.

The animal I have not observed. The soft parts are “ dunkel-schwarz-violett ” according to Pfeffer.

Dimensions, 10 to 11 mm.

Habitat. — North Atlantic Ocean, Davis Strait (“Valorous” Expedition), 44° N., 31° W. (Hamburg Museum).

Challenger Specimens. — Deposit shells.

Station 78, July 10, 1873 ; off the Azores; lat. 37° 26' N., long. 25° 13' W.; depth, 1000 fathoms ; bottom, volcanic mud.

Station 85, July 19, 1873 ; off Palma Island (Canaries) ; lat. 28° 42' N., long. 18° 6' W.; depth, 1125 fathoms; bottom, volcanic mud.

Station 120, September 9, 1873 ; off the coast of South America, between Pernambuco and Bahia; lat. 8° 37' S., long. 34° 28' W.; depth, 675 fathoms; bottom, red mud.

REPORT ON THE PTEROPODA.

61

♦ *9. Clio balantium (Rang).

1829. Balantium recurvum, Anonymous (Children, fide Gray), Journ. Roy. Inst., vol. xv. p. 220,

pi. vii. fig. 107.

1834. Cleodora balantium, Rang, Magasin de Zoologie, 1834, pi. xliv.

1836. Hyalsea balantium, d’Orbigny, Voyage dans lAmerique meridionale, t. v. p. 116, pi. viii.

figs. 1-4.

1837. Balantium bicarinatum , Benson, Notice on Balantium, a Genus of the Pteropodous

Mollusca, Journ. Asiat. Soc. Bengal, vol. vi. p. 151.

1852. Cleodora infiata, Souleyet, Voyage de la Bonite, Zoologie, t. ii. p. 188, pi. vii. figs. 17-19 (young).

For description and figures, I refer to Souleyet, Voyage de la Bonite, Zoologie, t. ii. p. 186, pi. vii. figs. 11-16.

Habitat. — Atlantic Ocean; intertropical (21° 30' N. to 19° 30' S., Boas); 44° N. (Atlantic?) (Pfeffer); toward 40' X., coast of America (Verrill, fragments).1

Indian Ocean; exclusively in the southern portion, 33° S. towards Africa (Boas), towards Australia (Pfeffer), Islands of St. Paul and Amsterdam (Benson).

Challenger Specimens. — Living.

Station 216a, February 16, 1875; north of New Guinea; lat. 2° 56' N., long. 134° 11' E. (young).

#10. Clio chaptali (Souleyet) (PI. II. fig. 7).

1852. Cleodora chaptali, Souleyet, Voyage de la Bonite, Zoologie, p. 183, pi. vii. figs. 1-5.

The above form appears to be a distinct species, but very strictly localised, for it has not been reobserved since its discovery by Souleyet. I only know a single adult specimen (dry shell), which is deposited in the British Museum.

Characters and Description. — Shell somewhat bulging, with its apex recurved dorsally, with its lateral edges uniformly and markedly diverging, in contrast to Clio balantium, where they describe a sigmoid curve. The lateral keels are sharp and not hollow-edged, as they are in Clio balantium ; they run parallel to the axis of the body, and are not at all turned ventrally ; this admits of the ventral surface being as bulging as the dorsal. The latter bears five longitudinal ribs, instead of three as in Clio balantium. The middle of the lips hardly projects anteriorly. The embryonic shell is separated from the rest by a well-marked constriction, in front of which the shell broadens out again. The embryonic portion, however, in contrast to that of Clio balantium, does not enlarge behind the constriction, and is terminated posteriorly by a much -pointed apex (PI. II. fig. 7).

The animal, according to Souleyet, very closely resembles Clio balantium.

1 Catalogue of the Marine Mollusca added to the fauna of New England during the past ten years, Trans. Connect Acad., vol. v. p. 557.

62

THE VOYAGE OF H.M.S. CHALLENGER.

Habitat. — Atlantic Ocean ; near the Cape of Good Hope (Souleyet).

Challenger Specimen. — Living, young.

Station 181, August 25, 1874 ; Fiji to Raine Island ; lat. 13° 50' S., long. 151° 49' E.

*11. Clio australis (d’Orbigny) (not Bruguiere) (PL II. fig. 8).

1836. Hyalasa australis,1 d’Orbigny, Voyage dans l’Amerique meridionale, t. v. p. 117, pL viii.

figs. 9-11.

1850. Balantium australe, Gray, Catalogue of the Mollusca in the Collection of the British

Museum, pt. ii., Pteropoda, p. 15.

1852. Gleodora australis, Souleyet, Voyage de la Bonite, Zoologie, t. ii. p. 189, pi. viii.

figs. 20-25.

For figures and description, see Souleyet ( loc . cit.).

Habitat. — This species appears to have a geographical distribution like that of Spongiobranchsea australis and Ihmacina australis, that is to say, localised in the southern regions of the three great oceans around the South Pole.

Cape Horn (d’Orbigny); South-east Pacific (48° S., 86° W., Souleyet); (?) south-east of the Cape of Good Hope, 38° 50' S. (Boas).

Challenger Specimens. — Living.

Station 159, March 10, 1874; Termination Land to Melbourne; lat. 47° 25' S., long. 130° 22' E.

Observations. — Boas2 has united with the present species Clio sulcata, Pfeffer. But the latter is certainly a distinct species, also collected towards the South Pole by the Challenger Expedition, and the embryonic shell3 which Boas has figured as that of “ Cleodora australis ” is precisely similar to Clio sulcata, and very different from that of Clio australis (PI. II. fig. 8). For in the latter the embryonic shell is separated from the other portion by a much broader and deeper constriction, and is terminated posteriorly by a rounded extremity.

#12. Clio sulcata (Pfeffer) (PI. II. figs. 9-11).

1879. Gleodora sulcata, Pfeffer, Uebersicht der auf S. M. Schiff Gazelle, und von Dr. Jagor

gesammelten Pteropoden, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1879, p. 240, figs. 11, 12.

Characters and Description. — Shell slender, with a very slight curvature, with the ventral surface only slightly projecting, but not re-entrant. The surface adorned with transverse ridges ; nine longitudinal ridges occur in close proximity on the anterior portion of the dorsal surface. The margins of the aperture, as Pfeffer has noted, are very fragile,

1 The name Hyalsea australis was already used in 1816 by Peron (Voyage de d4couvertes aux terres australes, pi. xxxi. fig. 5), but it only occurs on the plate, and no description is given. As the figure refers to Cavolinia tridentata, I think the specific title australis may be fitly retained for the above species of Clio.

2 Spolia atlantica, p. 68. 3 Ibid., pi. iv. fig. 46.

REPORT OR THE PTEROPODA.

63

so that it is difficult to describe the exact form of the lips, though this is probably intermediate between that of Clio australis and that of Clio p yramidata . The embryonic shell is almost directly continuous with the other portion, from which it is separated only by a narrow groove. The posterior extremity is pointed.

The figure 1 7c of Pfeffer (pi. vii., loc. cit.) represents the curvature of the shell as if it were ventral. The specimen figured must then have been abnormal, for in all the specimens of Clio sulcata i which I have seen the curvature was dorsal, as it is indeed in all the curved Cavoliniidse.

The animal resembles that of neighbouring species ( Clio australis and Clio pyramidata). The left tentacle is readily visible ; the posterior lobe of the foot is of considerable length, and the other external characters are those of the genus Clio in the strict sense. There are no lateral prolongations of the margins of the mantle.

This form is undoubtedly a distinct species which cannot be referred either to Clio australis (as by Boas) or to Clio pyramidata. It differs from both in the fact that the ventral surface of the shell is not at all re-entrant. And further it differs from Clio australis (with which it has a closely analogous geographical distribution) in its much more divergent lateral margins and in its embryonic shell, as may be seen by comparing the figures of the two species. This form was the Clio observed on the last expedition of the “ Astrolabe,” to which I have referred in my Beport on the Gymnosomata.1

Dimensions. — The shell measures 2 cm. in length.

Habitat. — Like Clio australis, this form was found in the southern region of the Pacific Ocean, lat. 50" 34/ S., long. 83° 44' W., and lat. 45° 35' S., long. 122° l' W. (Pfeffer); also in the Southern Ocean, near Kerguelen Island; and in the Antarctic Ocean (see the following Challenger localities).

Challenger Specimens. — Living specimens.

Station 150, February 2, 1874 ; Heard Island ; lat. 52° 4' S., long. 71° 22' E.

Between Stations 154 and 155, February 21, 1874; in vicinity of Antarctic ice; lat. 63° 30' S., long. 89° 8' E.

Station 156, February 26, 1874; in vicinity of Antarctic ice; lat. 62° 26' S.; long. 95° 44' E.

*13. Clio pyramidata, Linne.

1767. Clio pr/ramidata, Linne, Systema Naturse, ed. 12, p. 1094.

1813. Hyaleea lanceolata, Lesueur, Me moire sur quelques especes d’animaux mollusques et

radiaires recueillis dans la Mdditerranee pres de Nice, Nouv. Bull. Soc. Philom. Paris, t. iii. p. 284, pi. v. fig. 3.

1825. Cleodora brovmii , De Blainville, Manuel de Malacologie, pi. xlvi. fig. 1.

1836. Hyahea pyramidata, d’Orbigny, Voyage dans l’Amerique meridionale, t. v. p. 113, pi. vii

figs. 25-29.

1841. Cleodora lamartinieri, Rang, in d’Orbigny, Mollusques de Cuba, p. 83.

1 Zool. Chall. Exped., pt. lviii. p. 62.

64

THE VOYAGE OF H.M.S. CHALLENGER.

1852. Cleodora lanceolata, Souleyet, Voyage de la Bonite, Zoologie, t. iL p. 179, pi. vi.

figs. 17-25.

1852. Cleodora exacuta, Gould, The Mollusca and Shells of the U.S. Exploring Expedition,

p. 488, pi. li. fig. 605.

1877. Cleodora Idbiata, Sowerby, in Reeve, Conchologia iconica, t. xx., Pteropoda, fig. 26.

1880. Cleodora martensii, Pfeifer, Die Pteropoden des Hamburger Museums, Abhandl. d.

Naturw. Ver. Hamburg, Bd. vii. p. 95, pi. vii. fig. 16.

For figures and description, see Souleyet ( loc . cit.).

Habitat. — This species has a cosmopolitan distribution, and exhibits noteworthy variations in form.

The most northerly locality is Spitzbergen (British Museum), then Bergen, Iceland, Davis Strait, the whole of the Atlantic towards both continents and down to 40° S., and all the Mediterranean.

Indian Ocean ; from the Gulf of Bengal to 40° S. (Boas), off the coasts of Africa, Natal, Zanzibar (Pfeffer), and as far as Australia, Swan River (British Museum).

Pacific Ocean ; western portion, Japan, Gulf of Yedo (“ Galathea” Expedition), Yellow Sea (British Museum), China Sea (Boas), Malay Archipelago, Eastern Australia to 40° S. (Pfeffer) ; North-east Pacific, 44° N., 154° W. (Gould, as “ Cleodora exacuta”) ; South-east Pacific, 27° 11' S., 88° 52' W. (“ Galathea” Expedition).

Challenger Specimens. — I. Living.

Station 62, June, 18, 1873 ; Bermuda to Azores ; lat. 35° 7' N., long. 52° 32' W.

Station 63, June 19, 1873 ; Bermuda to Azores ; lat. 35° 29' N., long. 50° 53' W.

Station 142, December 18, 1873 ; Cape of Good Hope to parallel of 46° S.; lat. 35° 4' S., long. 18° 37' E.

Near Station 160, March 15, 1874 ; off Melbourne ; lat. 39° 45' S., long. 140° 40' E.

Station 175, August 12, 1874 ; Fiji to Raine Island ; lat. 19° 2' S., long. 177° 10' E.

Station 230, April 5, 1875 ; Admiralty Islands to Yokohama; lat. 26° 29' N.,

long. 137° 57' E.

Station 251, July 10, 1875; Yokohama to Sandwich Islands; lat. 37° 37' N.,

long. 163° 26' W.

Station 254, July 17, 1875 ; Yokohama to Sandwich Islands; lat. 35° 13' N.,

long. 154° 43' W.

Station 256, July 21, 1875; Yokohama to Sandwich Islands; lat. 30° 22' N.,

long. 154° 56' W.

Station 293, November 1, 1875 ; Tahiti to Valparaiso ; lat. 39° 4' S., long. 105° 5' W.

Station 332, March 10, 1876 ; Rio de Janeiro to Tristan da Cunha; lat. 37° 29' S., long. 27° 31' W.

Between Stations 332 and 333, April 28, 1876 ; off St. Vincent (Cape Verde) ; lat. 17° 47' N., long. 28° 28' W.

On May 12, 1876 ; off the Azores ; lat. 42° 52' N., long. 28° 54' W.

REPORT ON THE PTEROPODA.

65

II. Deposit shells.

Station A III., February 12, 1873; off Canary Islands; lat. 28° 3' 15" N., long. 17° 27' 0" AY.; depth, 620 fathoms; bottom, volcanic mud.

Station 3, February 18, 1873 ; Tenerife to Sombrero Island; lat. 25° 45' N., long. 20° 14' AY.; depth, 1525 fathoms; bottom, hard ground.

Station 23, March 15, 1873 ; off Sombrero Island ; lat. 18° 24' N., long. 63° 28' AY.; depth, 450 fathoms ; bottom, Pteropod ooze.

Station 24, March 25, 1873; off Culebra Island; lat. 18° 38' 30" N., long. 65° 5' 30" AY.; depth, 390 fathoms; bottom, Pteropod ooze.

Station 33, April 4, 1873; off Bermuda ; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

Station 35c, April 22, 1873; off Bermuda; lat. 32° 15' N., long. 65° 8' W.; depth, 1950 fathoms ; bottom, Globigerina ooze.

Station 75, July 2, 1873; off Fayal (Azores); lat. 38° 38' 0" N., long. 28° 28' 30" AY.; depth, 450 fathoms; bottom, volcanic mud.

Station 76, July 3, 1873; off the Azores; lat. 38° 11' N., long. 27° 9' AV.; depth, 900 fathoms ; bottom, Pteropod ooze.

Station 78, July 10, 1873 ; off the Azores; lat. 37° 26' N., long. 25° 13' AY.; depth, 1000 fathoms; bottom, volcanic mud.

Station 85, July 19, 1873 ; off Palma Island (Canaries) ; lat. 28° 42' N., long. 18° 6' AY.; depth, 1125 fathoms; bottom, volcanic mud.

Station 120, September 9, 1873 ; off the coast of South America, between Pernam- buco and Bahia; lat. 8° 37' S., long. 34° 28' VV.; depth, 675 fathoms; bottom, red mud.

Station 122, September 10, 1873 ; off the coast of South America, between Pernam- buco and Bahia; lat. 9° 5' S., long. 34° 50' AY.; depth, 350 fathoms; bottom, red mud.

Station 164, June 12, 1874; off Sydney; lat. 34° 8' S., long. 152° 0' E.; depth, 950 fathoms ; bottom, green mud.

Station 185, August 31, 1874 ; off Raine Island; lat. 11° 35' 25" S., long. 144° 2' 0" E.; depth, 135 fathoms; bottom, coral sand.

Station 219, March 10, 1875; Admiralty Islands to Yokohama; lat. 1° 54' 0" S., long. 146° 39' 40" E.; depth, 150 fathoms; bottom, coral mud.

Station 246, July 2, 1875; Yokohama to Sandwich Islands; lat. 36° 10' N., long. 178° 0' E.; depth, 2050 fathoms; bottom, Globigerina ooze.

Station 323, February 28, 1876 ; Falkland Islands to Rio de la Plata ; lat. 35° 39' S., long. 50° 47' AY.; depth, 1900 fathoms; bottom, blue mud.

Station 335, March 16, 1876 ; Tristan da Cunha to Ascension Island ; lat. 32° 24' S long. 13° 5' AY.; depth 1425 fathoms; bottom, Pteropod ooze.

(ZOOL. CHALL. EXP. — PART LXV. 1887.)

Ttt 9

66

THE YOYAGE OF H.M.S. CHALLENGER.

*14. Clio cuspidata (Bose).

1802. Hyalxa cuspidata, Bose, Histoire naturelle des Coquilles, t. ii. p. 241, pi. ix. figs. 5-7.

1820. Hyalxa tricuspidata , Bowdich, Elements of Conehology, pi. vi. fig. 1.

1830. Cleodora lessonii, Bang, MS., in Lesson, Voyage autour du Monde de la Coquill e, t. ii. pt. i. p. 247, pi. x. fig. 1.

1833. Cleodora cuspidata, Quoy et Gaimard, Voyage de 1’ Astrolabe, Zoologie, t. ii. p. 384,

pi. xxvii. figs. 1-5.

1852. ? Cleodora quadrispinosa, Bang, Histoire naturelle des Mollusques Pteropodes, pi. v.

fig. 6.

For figures and description see Souleyet, Voyage de la Bonite, Zoologie, t. ii. p. 176, pi. vi. figs. 11-16.

Habitat. — Atlantic Ocean, from 60° N. to 37° S.; Mediterranean; Indian Ocean, from Ceylon to 42° S., from Africa to Australia.

It has not been recorded from the Pacific previously to the Challenger Expedition.

Challenger Specimens. — I. Living specimens.

Near Station 230, April 4, 1875 ; Admiralty Islands to Yokohama; lat. 25° 33' N., long. 137° 57' E.

Station 254, July 17, 1875; Yokohama to Sandwich Islands; lat. 35° 13' N., long. 154° 43' W.

II. Deposit shells.

Station 23, March 15, 1873 ; off Sombrero Island ; lat. 18° 24' N., long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

Station 78, July 10, 1873 ; off the Azores ; lat. 37° 26' N., long. 25° 13' W.; depth, 1000 fathoms; bottom, volcanic mud.

Station 85, July 19, 1873 ; off Palma Island (Canaries); lat. 28° 42' N., long. 18° 6' W.; depth, 1125 fathoms; bottom, volcanic mud.

Cuvierina? Boas.

1825. Cuvieria, Bang, Description de deux genres nouveaux appartenant a la classe des Pteropodes, Ann. d. Sci. Nat., s4r. 1, t. xii. p. 322 (not P4ron, 1807).

Triptera, auctorum, not Quoy and Gaimard.

1886. Cuvierina, Boas, Spolia atlantica, p. 131.

Characters and Description. — Shell straight, elongated, with a smooth surface, with the posterior half conical and pointed, generally caducous in the adult. The anterior half is swollen medianly, but constricted behind the aperture. A partition, concave in front, is found towards the middle of the entire length of the shell, and close beside this the truncation is formed. The transverse section is circular, except towards the aperture, where it is a little compressed, and appears somewhat reniform. Behind

1 Named after Cuvier.

REPORT ON THE PTEROPODA.

67

the aperture the shell is contracted, but bulges out again towards the partition. The embryonic portion is separated from the rest of the shell by a shallow constriction.

Animal with the aperture of the mantle as large as that of the shell, with fins as in Clio ( Styhola ) subula and other species of Clio in the strict sense. The posterior portion of the foot is slightly hollowed out in its middle region.

Adult specimens with the posterior portion intact are very rare. Benson1 and d’Orbigny2 were the first independently to describe the form of the entire shell, which was not known to Rang; when he established the genus “ Cuvieria.”

Cuvierina is nearly allied to Clio, so much so indeed that Souleyet 3 4 was inclined to unite “ Cuvieria ” with “ Cleodora ” as a single division or subgenus. Similarly, according to Lesson/ Rang proposed in his unpublished Monograph to unite the above forms in a subgenus of “ Cleodora.”

Among all the species of the genus Clio, Clio ( Styliola ) subula exhibits the closest affinity with Cuvierina. Nevertheless, the constriction of the shell behind the mouth, the median partition, and the constant truncation, definitely distinguish Cuvierina from all the forms of Clio, and warrant its position as a distinct genus.

But, on the other hand, there is no sufficient reason to establish a distinct family, as Gray 5 and the brothers Adams 6 have done.

It is an entire abuse of nomenclature to apply to this genus the title Triptera, Quoy and Gaimard. Nothing could be more uncertain than what Triptera rosea 7 really is, as the title is applied to a Pteropod without a shell.

The genus Cuvierina includes only a single living species.

* Cuvierina columnella (Rang).

1824. ? Cleodora obtusa, Quoy et Gaimard, Voyage de rtJranie, Zoologie, p 415, pi. lxvi.

fig. 5.

1827. Cuvieria columnella, Rang, Description, de deux nouveaux genres appartenant a la classe

des Pteropodes, Ann. d. Sci. Nat., ser. 1, t. xiii. p. 323, pi. xlv. figs. 1-8.

1835. Cuvieria oryza, Benson, Corrected characters of the genus Cuvieria and Notice of a second species inhabiting the tropical Indian Ocean, Journ. Asiat. Soc. Bengal, vol. iv. p. 698.

1850. Triptera columnella, Gray, Catalogue of the Mollusca in the Collection of the British

Museum, pt. ii., Pteropoda, p. 23.

1 Corrected characters of the genus Cuvieria of Rang, &c., Journ. Asiat. Soc. Bengal, vol. iv. p. 698, 1835.

2 Voyage dans l’Amerique meridionale, t. v. pp. 124, 125, pi. viii. fig. 36.

3 Voyage de la Bonite, Zoologie, t. ii. p. 203.

4 Voyage autour du Monde de la Coquill e.

5 Catalogue of the Mollusca in the Collection of the British Museum, pt. ii., Pteropoda, p. 23.

6 The Genera of Recent Mollusca, vol. i. p. 54.

7 Description de cinq genres de Mollusques, &c., Ann. d. Sci. Nat., ser. 1, t. vi. p. / 6, pi. ii. fig. 5, 1825.

68

THE VOYAGE OF H.M.S. CHALLENGER.

1850. Cuvieria urceolaris, M0rch, Catalogus conch yliorum quae reliquit C. P. Kjerulf,

p. 32.

1879. Triptera columella (sic), Pfeffer, Uebersicht der auf S.M. Schiff “ Gazelle ” und von Dr.

Jagor gesammelten Pteropoden, Monatsber. d. k. preuss.

Akad. d. Wiss. Berlin, 1879, p. 243, fig. 18.

1879. Triptera cancellata, Pfeffer, Ibid., p. 243, fig. 19.

For description and figures I refer to Souleyet, Voyage de la Bonite, Zoologie, t. ii. p. 205, pi. xii. The best figure of the complete shell is to be found in the Spolia atlantica of Boas, pi. iii. fig. 39.

Habitat. — Atlantic Ocean ; from 43° 23' N. (Boas) to 40° S., both towards the New and Old Worlds. According to Souleyet, this species has been found towards Cape Horn, but this appears to me to require confirmation. The locality Spitzbergen, noted in the British Museum, is certainly erroneous.

Indian Ocean; from the Gulf of Bengal (British Museum) to 35° 30' S., from Africa (Zanzibar, the Cape, &c.) to Australia.

Pacific Ocean ; western portion, China Sea (Boas), Malay Archipelago, east coast of Australia (Pfeffer and Angas) ; eastern portion, from 23° N. to 42° S. (Knocker).

Challenger Specimens. — I. Living specimens.

Station 53, May 26, 1873 ; Halifax to Bermuda; lat. 36° 30' N., long. 63° 40' W.

Station 62, June 18, 1873 ; Bermuda to Azores ; lat. 35° 7' N., long. 52° 32' W.

Station 63, June 19, 1873 ; Bermuda to Azores ; lat. 35° 29' N., long. 50° 53' W.

Station 175, August 12, 1874 ; Fiji to Raine Island; lat. 19° 2' S., long. 177° 10' E.

Station 181, August 25, 1874 ; Fiji to Raiue Island ; lat. 13° 50' S., long. 151° 49' E.

Station 216a, February 16, 1875; north of New Guinea; lat. 2° 56' N.,

long. 134° 11' E.

Station 230, April 5, 1875; Admiralty Islands to Yokohama; lat. 26° 29' N., long. 137° 57' E.

Station 254, July 17, 1875; Yokohama to Sandwich Islands; lat. 35° 13' N.,

long. 154° 43' W.

Station 280, October 4, 1875 ; Tahiti to Valparaiso ; lat. 18° 40' S., long. 149° 52' W.

Station 288, October 21, 1875 ; Tahiti to Valparaiso ; lat. 40° 3' S., long. 132° 58' W.

Near Station 288, October 22, 1875 ; Tahiti to Valparaiso; lat. 40° O' S.,

long. 131° 36' W.

Station 294, November 3, 1875 ; Tahiti to Valparaiso ; lat. 39° 22' S., long. 98° 46' W.

Near Station 354, May 7, 1876 ; St. Vincent towards Azores; lat. 34° 22' S.,

long. 34° 23' W.

II. Deposit shells.

Station 23, March 15, 1873 ; off Sombrero Island; lat. 18° 24' N.: long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

REPORT OjST THE PTEROPODA.

69

Station 24, March 25, 1873 ; off Culebra Island; lat. 18° 38' 30" N., long. 65° 5' 30" W.; depth, 390 fathoms; bottom, Pteropod ooze.

Station 33, April 4, 1873 ; off Bermuda; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

Station 78, July 10, 1873 ; off the Azores; lat. 37° 26' N., long. 25° 13' W.; depth, 1000 fathoms ; bottom, volcanic mud.

Station 85, July 19, 1873 ; off Palma Island (Canaries) ; lat. 28° 42' N., long. 18° 6' W.; depth, 1125 fathoms; bottom, volcanic mud.

Station 120, September 9, 1873 ; off the coast of South America, between Pernam- buco and Bahia ; lat. 8" 37' S., long. 34° 28' W.; depth, 675 fathoms ; bottom, red mud.

Station 122, September 10, 1873 ; off the coast of South America, between Pernam- buco and Bahia; lat. 9° 5' S., loug. 34° 50' W.; depth, 350 fathoms; bottom, red mud.

Station 185, August 31, 1874; off Raine Island ; lat. 11° 35' 25" S., long. 144' 2' 0" E.; depth, 135 fathoms; bottom, coral sand.

Station 335, March 16, 1876 ; Tristan da Cunha to Ascension Island ; lat. 32° 24' S., long. 13° 5' AV.; depth 1425 fathoms; bottom, Pteropod ooze.

Gavolinia / Abildgaard.

1791. Carolina, Abildgaard, Om Cavolina natans, Anomia tridentata Forskalsei, Skriv. Naturkist.

Selsk., Bd. i. Heft. ii. p. 173 ( non Bruguiere, 1792).

1797. Hheda, Humphreys, Museum Calonnianum.

1801. Hyalxa, Lamarck, System e des animaux sans vertebres, p. 139.

1810. Archonta, Montfort, Conchyliologie syt4matique, t. it p. 50.

1815. Trida, Oken, Lehrbuch der Zoologie, t. i. p. 327 (err. hyp. 273).

1825. Pleuropus, Eschscholtz, Bericht iiber die Zoologische Ausbeute wahrend der Reise von Cronstadt bis St. Peter und Paul, Oken, Isis, 1825, Bd. i. p. 735.

1842. Diacria, Gray, Synopsis of the Contents of the British Museum.

1859. Orbignyia, A. Adams, On synonyms and habitats of Cavolinia, Diacria, and Pleuropus, Ann. and Mag. Hat. Hist., ser. 3, vol. iii. p. 45.

Characters and Description. — -The shell, which is generally of a horny brown colour, is especially characterised (in the adult state, of course) by its much-contracted aperture, which is, however, very broad transversely. The lateral portions of this aperture, which are narrower than the middle part, are almost separated from it by a more or less developed tooth rising from the ventral lip and fitting into a dorsal depression. The dorsal lip, which is longer than the ventral, is always more or less ventrally recurved ; the ventral lip, much recurved dorsally, is constricted a little in front of the aperture, and then reflected ventrally. The ventral surface is always bulging. The special form of Cavolinia depends on the fact that the sides of the shell

1 Named after Cavolini or Caulini.

70

THE VOYAGE OF H.M.S. CHALLENGER.

diverge abruptly outwards so that the lips appear much prolonged anteriorly. The sides of the shell are often prolonged into a more or less projecting point. The embryonic shell is not separated by a distinct constriction, except in Cavolinia trispinosa and Cavolinia quadridentata.

The animal somewhat resembles in its external characters the species of Clio strictly so called. Its special characters chiefly consist in the breadth of the posterior lobe of the foot and in the presence of lateral prolongations of the mantle, which project from the lateral portions of the aperture (side clefts of the adult) and may cover a considerable portion of the shell.

Many authors (A. Adams, Gray, Fischer, Boas, &c.) call this genus “ Cavolinia, Gioeni,” and do so on the authority of Abildgaard, according to whom Gioeni first used this title in his work entitled “ Descrizione di una nuova Famiglia e di un nuovo Genere di Testacei trovati nel littorali di Catania.” This small memoir (8vo and not 4to as is always noted) is somewhat rare, and does not appear to have been actually seen by the authors who cite it from Abildgaard. For in the memoir itself it may be seen that while Gioeni has indeed represented Cavolinia tridentata in his figures xiv.-xvi., he does not give it its title. Caulini is referred to on p. xxvii, note a, as the first to observe the animal of this species, but there is no question of naming in his honour the “nuovo Genere di Testacei.”

The name “ Cavolina” (em. Cavolinia ) only dates from 1791, and its author was Abildgaard. It has, nevertheless, the priority over Cavolinia, Bruguiere, which was not published till 1792,1 and ought to be employed in preference to the title Hyalsea, Lamarck, 1801.

Although the shells of Cavolinia have a much constricted aperture, different individuals within the same species may exhibit very noteworthy divergences in regard to size. The difference is sometimes very striking, so that in some species the diameter of certain individuals may be four times that of others ( Cavolinia longirostris, after Boas).2

From this fact it has been inferred (Pfeffer)3 that, in order to grow, the shells of Cavolinia must first of all lose all the contracted portion by absorption, since growth can only take place by the apposition of fresh material at the margin of the aperture.

But this hypothesis of partial absorption is altogether imaginary. As Boas has already pointed out,4 there is no trace of a line of reabsorption on the shells of large size, and it is further a very strong argument against the theory that the posterior (oldest) portion of the small individuals does not correspond exactly to the homologous portion

1 Encyclopedic Methodique ; Histoire naturelle des Vers, t. i.

2 Spolia atlantica, p. 206.

3 Die Pteropoden des Hamburger Museums, Abhandl. Naturw. Ver. Hamburg, t. vii. p. 75.

4 Spolia atlantica, p. 207.

REPOET OX THE PTEROPODA.

71

of the large specimens, which, however, it is bound to do, if in the latter the contracted portion is absorbed and the posterior portion alone left. This residue ought obviously to be identical and superposable in individuals of any size whatever.

The small-sized specimens, like the large, are individuals which will not increase further, which have attained then limit of growth, as is otherwise indicated by the complete development of the reproductive system. The smaller size of the shell depends on its surface being developed along a curve with smaller radius than in the large-sized individuals.

On the other hand, there are several forms of Cavoliniidse, to which distinct specific titles are given, notably those which Boas calls “ Hyales plates,” where the union of the two lips of the shell by the so-called ‘ ' appareil de fermeture” has not been developed. All these forms, as we shall immediately show, are individuals which have not yet attained sexual maturity, and belong to species already known, as Cantraine first suspected.

But this condition of immaturity, associated as it undoubtedly is with reduced development of the reproductive organs,1 may be prolonged to a very late stage, and the shell may be very large before the formation of the “ appareil de fermeture.” This can be easily demonstrated by examining a large number of specimens, as for instance of Cavolinia tridentata at Naples. In this form, to which our attention was first directed by Dr. Paul Schiemenz, one finds, even at the same stage of development, considerable difference in size.

It is certain that there are notable differences in the size of adult specimens (with completely developed reproductive organs, and with perfected closing apparatus) ; and the theory of the partial absorption of the shell must be dismissed.

But as I have already pointed out, those young stages which we have discussed have been regarded as distinct species, and have been referred either to the genus Cavolinia ( Hyalsea ) or to the genus Clio {Cleodora), or to a special genus, Pleuropus.

And besides these entirely superfluous terms, we also find for the forms which properly belong to this genus a profuse superabundance of specific titles, just as in the cases of Clio and the Limacinidse.

As these Thecosomata are pelagic animals with a very wide geographical distribution, there is no inconsiderable exhibition of variation in the form of the shell. Thus have arisen numerous variations, distinguished by very slight divergences. But on the basis of minimal distinctions, conchologists have not hesitated to establish a large number of “new” species.

If we abstract the titles which ought to be referred to other genera altogether2

1 See Gegenbaur {Hyalsea complanata), Untersuchungen fiber Pteropoden und Heteropoden, pi. i. fig. 1 ; Souleyet {Hyalsea Isevigata), Voyage de la Bonite, Zoologie, pi. v. fig. 14; Huxley {Cleodora curvata), On the Morphology of the Cephalous Mollusca, Phil. Trans., 1853, pi. iv. figs. 4, 5.

2 Also Nudibranchs, designated Cavolina (Bruguiere).

72

THE VOYAGE OF H.M.S. CHALLENGER.

(d’Orbigny placed in the genus Hyalsea = Cavolinia all the members of the family Cavoliniidse), or even to other groups, and confine our attention to the forms really belonging to this genus, we shall find, for extant species, fifty-four specific titles, of which three are used with several connotations, which increases the mischief still further.

Hyalsea affinis, d’Orbigny.

Hyalsea angulata, Souleyet.

Hyalsea australis, Peron.

Hyalsea chemnitziana, Peron and Lesueur.

Hyalsea complanata, Gegenbaur. Cleodora compressa, Souleyet. Hyalsea cornea, Lamarck.

Hyalsea costata, Pfeffer.

Hyalsea cumingii, Sowerby.

Cleodora curvata, Souleyet.

Hyalsea cuspidata, Delle Chiaje (non Bose).

Hyalsea depressa, Bivona ( non d’Orbigny).

Hyalsea depressa, d’Orbigny. Hyalsea ecaudata, Lesueur.

Hyalsea elongata, Lesueur.

Hyalsea femorata, Gould.

Hyalsea fissirostris, Benson.

Hyalsea jlava, d’Orbigny.

Hyalsea forskahlii, Lesueur.

Hyalsea gegenbauri, Pfeffer.

Hyalsea gibbosa, Rang.

Hyalsea globulosa, Rang.

Pleuropus hargeri, Verrill.

Hyalsea imitans, Pfeffer.

Hyalsea inermis, Gould.

Hyalsea inflexa, Lesueur.

Hyalsea intermedia, Sowerby. Hyalsea labiata, d’Orbigny.

Hyalsea Isevigata ~ d’Orbigny.

Hyalsea vagin

Hyalsea limbata, d’Orbigny. Pleuropus longifilis, Troschel. Hyalsea longirostris, Lesueur. Hyalsea minuta, Sowerby.

Hyalsea mucronata, Quoy and Gaimard.

Carolina natans, Abildgaard. Hyalsea obtusa, Sowerby.

Hyalsea papilionacea, Quoy and Gaimard.

Pleuropus pellucidus, Eschscholtz. Hyalsea peroni, Lesueur.

Carolina pisum, Mprch.

Cleodora pygmsea, Boas.

Hyalsea quadridentata, Lesueur. Hyalsea quadrispinosa, d’Orbigny. Hyalsea reeriana, Dunker.

Hyalsea rotundata, Boas.

Hyalsea rugosa, d’Orbigny.

Hyalsea teniobranchea, Peron and Lesueur.

Hyalsea triacantha, Bronn.

Anomia tridentata, Forsk&l. Cleodora trifilis, Troschel.

Hyalsea trispinosa, Lesueur.

Hyalsea truncata, Krauss ( non Lesueur).

Hyalsea truncata, Lesueur.

Hyalsea uncinata, Hoeninghaus ( non Rang).

Hyalsea uncinata, Rang.

Hyalsea uncinatiformis, Pfeffer.

’, Cantraine.

REPORT ON THE PTEROPODA.

73

An attentive examination of this superfluity of titles shows that there are amongst them only eight genuine species, all obtained on the Challenger Expedition.

All the other titles are synonyms of these eight species. It is necessary, however, to distinguish : —

1. Thirteen titles referring to the young stages of several of these eight forms : —

Hyalsea complanata, Gegenbaur, Hyalsea depressa, d’Orbigny, . Hyalsea laevigata, d’Orbigny,

Hyalsea rotunda ta, Boas,

Hyalsea rugosa, d’Orbigny,

Hyalsea truncata, Lesueur,

Cleodora compressa, Souleyet, . Cleodora curvata, Souleyet,

Cleodora pygmsea , Boas,

Cleodora trijilis, Troschel,

Pleuropus hargeri, Yerrill,

Pleuropus longiJUis, Troschel, . Pleuropus pellucidus, Eschscholtz,

2. Four titles which may be applied to

Hyalsea affinis, d’Orbigny,

Hyalsea costata, Pfeffer,

Hyalsea labiata, d’Orbigny,

Hyalsea truncata, Krauss,

= Cavolinia tridentata, Forskal.

= Cavolinia injlexa, Lesueur.

= Cavolinia longirostris, Lesueur.

= Cavolinia globidosa, Rang.

= Cavolinia gibbosa, Rang.

= Cavolinia sp.

= Cavolinia trispinosa, Lesueur.

= t Cavolinia uncinata, Rang.

= Cavolinia quadridentata , Lesueur. = Cavolinia sp.

= Cavolinia gibbosa, Rang.

= Cavolinia tridentata, ForskSl.

= Cavolinia injlexa, Lesueur.

>cal varieties of some species : —

= var. of Cavolinia tridentata.

= var. of Cavolinia quadridentata.

= var. of Cavolinia injlexa.

= var. of Cavolinia tridentata.

3. All the other titles are absolutely synonymous species : —

Hyalsea angulata, Souleyet,

Hyalsea australis, Peron,

Hyalsea chemnitziana,!* eron and Lesueur, Hyalsea cornea, Lamarck,

Hyalsea cumingii, Sowerby,

Hyalsea cuspidata, Delle Chiaje,

Hyalsea depressa , Bivona,

Hyalsea ecaudata, Lesueur,

Hyalsea elongata, Lesueur,

Hyalsea femorata, Gould,

Hyalsea jissirostris, Benson,

(ZOOL. CHALL. EXF. PART LXV. 1887.)

with those of the eight genuine = Cavolinia longirostris.

>

• = Cavolinia tridentata.

| = Cavolinia trispinosa.

= Cavolinia longirostris.

= Cavolinia injlexa.

j = Cavolinia longirostris.

Ttt 10

74

THE VOYAGE OF H.M.S. CHALLENGER.

Hyalaea flara, d’Orbigny,

Hyalasa forskahlii, Lesueur,

Hyalaea gegenbauri, Pfeffer,

Hyalaea imitans, Pfeffer,

Hyalaea inermis, Gould,

Hyalaea intermedia, Sowerby, .

Hyalaea limbata, d’Orbigny,

Hyalaea minuta, Sowerby,

Hyalaea mucronata, Quoy and Gaimard, Carolina nutans, Abildgaard, .

Hyalaea obtusa, Sowerby,

Hyalaea papilionacea, Quoy and Gaimard, ] Hyalaea peroni, Lesueur, . . J

Carolina pisum, M0rch,

Hyalaea quadrispinosa, d’Orbigny, Hyalaea reeriana, Dunker,

Hyalaea teniobranchea,¥ eron andLesueur, Hyalaea triacantha, Bronn,

Hyalaea uncinata, Hoeninghaus,

Hyalaea nncinatiformis, Pfeffer,

Hyalaea raginellina, Cantraine,

= Carolinia gibbosa .

= Carolinia tridentata .

= Carolinia gibbosa.

= Carolinia injlexa.

= Carolinia quadridentata.

— Carolinia longirostris.

— Carolinia quadridentata.

— Carolinia trispinosa.

— Carolinia tridentata.

= Carolinia longirostris.

— Carolinia tridentata.

= Carolinia globulosa.

= Carolinia quadridentata.

— Carolinia trispinosa.

— Carolinia tridentata.

= Carolinia trispinosa.

= Carolinia injlexa.

— Carolinia uncinata. Carolinia injlexa.

There remain the following eight titles, which represent genuine and distinct species : —

Hyalaea trispinosa, Lesueur. Hyalaea quadridentata, Lesueur. Hyalaea longirostris, Lesueur. Hyalaea globulosa, Rang.

Hyalaea gibbosa, Rang. Anomia tridentata, Forsk&I Hyalaea uncinata, Rang. Hyalaea injlexa, Lesueur.

From the above list of synonyms of Carolinia, it appears that a number of generic titles have been applied to the preseut group of Thecosomata.

One may well ask if all these names should be rejected and none retained, or, in other words, if the genus Carolinia is indeed homogeneous and indivisible. It appears to me so to be beyond dispute.

I. Rheda, Hyalaea, Archonta, and Tricla are absolutely synonymous with Carolinia, for the simple reason that they refer to the same type, Anomia tridentata of Forsk&l.

II. Pleuropus is a designation based on young stages of typical Carolinia, which Boas names “ Hyalaea, B.”1 They refer to specimens in which the closing apparatus was not yet developed — Pleuropus pellucidus, Pleuropus longijilis, Pleuropus hargeri. Gray

1 Spolia atlantiea, p. 92.

REPORT ON THE PTEROPODA.

75

was the first 1 to note the affinities of “ Cleodora curvatci,” Souleyet, to this group, but he did not detect what these four forms really represented, and regarded “Pleuropus” as a group within the genus Clio.

The adults of most of the species of Pleuropus are known. As to the others, it is possible to predict, from some of their features, what forms they will probably turn out to be when arrived at sexual maturity. The designation Pleuropus is therefore to be abandoned.

III. Diacria is a characteristic conckological genus. Gray erected it for the reception of Cavolinia trispinosa and two young stages of typical Cavolinia forms (group B of Boas), viz., Hyalsea depressa, d’Orbigny, and Hyalsea laevigata, d’Orbigny, which it would have been more natural to place beside Pleuropus. He leaves in the genus Cavolinia, Cavolinia quadridentata, though it is in all respects the neighbour of Cavolinia trispinosa. And, further, he places the same species ( Cavolinia orbignyi, Rang, fossil) both in the genus Diacria and in the genus Cavolinia .2

On the other hand, the brothers Adams,3 and others after them, take this title Diacria as synonymous with Pleuropus, 1 and therefore add to Cavolinia trispinosa and to the two forms Hyalsea depressa and Hyalsea laevigata all the other young forms regarded as independent species. At the same time they agree with Gray in leaving Cavolinia quadridentata, separated from Cavolinia trispinosa, beside the typical Cavolinia forms.5

Now, it is certain that if Cavolinia trispinosa is to be separated from the other species of Cavolinia, Cavolinia quadridentata must go with it. The two species are in their structure most closely allied, and form a well-defined subgroup contrasting with the six other species.

And if, in their embryonic shell, in the form of their fins, and in the posterior portion of the foot, they present resemblances to Clio [Cleodora), they at the same time exhibit the characteristic features of Cavolinia in a way that makes separation impos- sible. They are certainly the most archaic living forms of the genus, but not sufficiently distinct to warrant a separate genus. One may, however, follow Boas in establishing a subsection ( Hyalsea , A), within the genus Cavolinia.

IV. Orbignyia, which was only regarded as a subgenus by A. Adams, is based on Cavolinia injlexa, which is usually considered as allied to Clio [Cleodora). There is,

1 Catalogue of the Mollusca in the Collection of the British Museum, pt. ii., Pteropoda, p. 14.

'l This Catalogue is in other respects full of inaccuracies and carelessness. It would he desirable to re-edit it, especially since the collection of Pteropods in the British Museum is many times richer to-day than it was in 1850.

3 The Genera of Recent Mollusca, vol. ii. p. 611.

4 Similarly Pfeffer, Uebersicht der auf S.M. Schiff Gazelle und von Dr. Jagor gesammelten Pteropoden, Monatsber. d. Jc. preuss. Alcad. d. Wiss. Berlin, 1879, p. 236.

5 Pfeffer (Die Pteropoden des Hamburger Museums, Abliandl. d. Naturiv. Ver. Hamburg, t. vii.) places Cavolinia trispinosa in the subfamily Cleodorinee, and Cavolinia quadridentata in the subfamily Hyaleinae.

76

THE VOYAGE OF H.M.S. CHALLENGER.

however, no warrant for this opinion. Cavolinia injlexa certainly belongs to the second Subgeneric section of Cavolinia, including the more typical or more highly specialised forms, all, in fact, except Cavolinia trispinosa and Cavolinia quadridentata. Its elongation and its flattening are not a whit more extraordinary than the expansion and shortening of Cavolinia globulosa.

From the above observations this results, that the huge list of species is reduced by analysis to eight, and that, without going to an extreme like d’Orbigny, who united all the Thecosomata of the family Cavoliniidse into a single genus Hyalaea, it may be said that at least the eight species above mentioned form a tolerably homogeneous unit within a single genus.

The eight species thus allowed to exist may be distinguished in the following fashion : —

Key to the Species.

I. Dorsal lip thickened into a pad.

1. Shell with lateral points, .....

2. Shell without lateral points, ....

II. Dorsal lip with a thin margin.

1. Posterior portion of the ventral lip markedly projecting laterally,

2. Ventral lip not more developed than the dorsal.

A. Shell without appreciable lateral points.

a. Shell narrower at the end of the lips than anteriorly.

a. Ventral surface rounded, .

/?. Ventral surface with an anterior transverse keel,

b. Shell as broad at the end of the lips as anteriorly,

B. Shell with distinct lateral points.

a. Upper lip flattened posteriorly, .

b. Upper lip directed straight forwards,

Cavolinia trispinosa. Cavolinia quadridentata.

Cavolinia longirostris.

Cavolinia globulosa. Cavolinia gibbosa. Cavolinia tridentata.

Cavolinia uncinata. Cavolinia injlexa.

The best series of figures of these eight species is undoubtedly that given by Boas.1 We shall, therefore, refer to these figures, since it is useless to figure afresh species already sufficiently well known, and hopeless to expect better figures than those of Boas.

#1. Cavolinia trispinosa (Lesueur).

1821. Hyalxa trispinosa, Lesueur, MS. in de Blainville, Hyale, Diet. d. Sci. Nat., t. xxii. p. 82. 1827. Hyalxa mucronata, Quoy et Gaimard, Observations Zoologiques faites a bord de

1’ Astrolabe, &c., Ann. d. Sci. Nat., ser. 1, t. x. p. 231, pi. viiiB, figs. 1, 2.

1832. Hyalxa depressa, Bivona, Descrizione di una nuova specie di Jale, &c., Efemeridi

scientifiche e litterarie per la Sicilia, p. 57, pi. i. figs. 4, 5.

1841. Hyalxa cuspidata, Delle Chiaje, Descrizione e notomia degli animali senza vertebre del

Regno di Napoli, pi. clxxx. figs. 1, 2 ( non d’Orbigny).

1 Spolia atlantica, pi. i. figs. 3-11 ; pi. ii. figs. 14-21.

REPORT ON THE PTEROPODA.

77

1850. Diacria trispinosa , Gray, Catalogue of the Mollusca iu the Collection of the British

Museum, pt. ii., Pteropoda, p. 10.

1850. Diacria mucronata, Gray, Ibid., p. 11.

1853. Hyalsea reeviuna, Dunker, Index Molluscorum, &c., p. 2, pi. i. figs. 17-20.

1858. Plearopus trispinosus , A. and H. Adams, The Genera of Recent Mollusca, vol. ii.

p. 611.

1858. Pleuropus mucronatus, A. and H. Adams, Ibid., vol. ii. p. 611.

For description and figures, see Boas, Spolia atlantica, p. 94, pi. i. fig. 3 ; pi. ii. fig. 14.

Habitat. — Atlantic Ocean; from 60 15' N. (“Triton” Expedition) to 40° S.

(Knocker), both towards the New World and towards the Old; Mediterranean (Delle Chiaje, Cantraine, Costa, Macdonald, &c.).

Indian Ocean; from the Gulf of Bengal (Pfeffer) to 41° S. (Boas), and from Africa (Natal, Madagascar, &c.) to Australia.

Pacific Ocean ; western portion, Yellow Sea (British Museum), China Sea (Boas), 13° N., 156° E. (“ Vettor Pisani” Expedition); South-west Pacific (Pfeffer), Port Jackson (Angas); North-east Pacific to 30° N. (Knocker).

Challenger Specimens. — I. Living specimens.

Station VIIf., February 2, 1873 ; off Madeira ; lat. 32° 27' 0" N., long. 16° 40' 30" W.

Station 62, June 18, 1873 ; Bermuda to Azores; lat. 35° 7' N., long. 52° 32' W.

Station 63, June 19, 1873 ; Bermuda to Azores; lat. 35° 29' N., long. 50° 53' W.

Station 181, August 25, 1874 ; Fiji to Paine Island ; lat. 13° 50' S., long. 151° 49' E.

Station 230, April 5, 1875; Admiralty Islands to Yokohama; lat. 26° 29' N., long. 137° 57' E.

O

II. Deposit shells.

Station 23, March 15, 1873 ; off Sombrero Island; lat. 18° 24' N., long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

Station 24, March 25, 1873 ; off Culebra Island ; lat. 18° 38' 30" N., long. 65° 5' 30" W.; depth, 390 fathoms; bottom, Pteropod ooze.

Station 33, April 4, 1873 ; off Bermuda; lat. 32° 21' 30" N., long. 64° 35' 55" W.; depth, 435 fathoms ; bottom, coral mud.

Station 35c, April 22, 1873; off Bermuda; lat. 32° 15' N., long. 65° 8' W.; depth, 1950 fathoms ; bottom, Globigerina ooze.

Station 70, June 26, 1873; Bermuda to Azores; lat. 38° 25' N., long. 35° 50' W.; depth, 1675 fathoms; bottom, Globigerina ooze.

Station 75, July 2, 1873; off Fayal (Azores); lat. 38° 38' 0" N., long. 28° 28' 30" W.; depth, 450 fathoms; bottom, volcanic mud.

Station 76, July 3, 1873; off the Azores; lat. 38° 11' N., long. 27° 9' W.; depth, 900 fathoms ; bottom, Pteropod ooze.

78

THE VOYAGE OF H.M.S. CHALLENGER.

Station 78, July 10, 1873 ; off the Azores; lat. 37° 26' N., long. 25° 13' W.; depth, 1000 fathoms; bottom, volcanic mud.

Station 85, July 19, 1873; off Palma Island (Canaries); lat. 28° 42' N., long. 18° 6' W.; depth, 1125 fathoms; bottom, volcanic mud.

Station 120, September 9, 1873; off the coast of South America, between Pernam- buco and Bahia; lat. 8° 37' S., long. 34° 28' W.; depth, 675 fathoms ; bottom, red mud.

Station 122, September 10, 1873 ; off the coast of South America, between Pernam- buco and Bahia; lat. 9° 5' S., long. 34° 50' W.; depth, 350 fathoms; bottom, red mud.

Station 164; June 12, 1874; off Sydney; lat. 34° 8' S., long. 152° O' E.; depth, 950 fathoms ; bottom, green mud.

Station 185, August 31, 1874; off Raine Island; lat. 11° 35' 25" S., long. 144° 2' 0" E.; depth, 135 fathoms; bottom, coral sand.

Station 335, March 16, 1876 ; Tristan da Cunha to Ascension Island ; lat. 32° 24' S., long. 13° 5' W.; depth, 1425 fathoms; bottom, Pteropod ooze.

*2. Ccivolinia quadridentata (Lesueur).

1821. Hyalxa quadridentata, Lesueur, MS., in Blainville, Hyale, Diet. d. Sci. Nat., t. xxii. p. 81. 1836. Hyalxa quadrispinosa, d’Orbigny, Voyage dans l’Amerique meridionale, t. v. p. 85.

1850. Carolina quadridentata, Gray, Catalogue of the Mollusca in the Collection of the British

Museum, pt. ii. , Pteropoda, p. 8.

1852. Hyalxa inermis, Gould, The Mollusca and Shells of the U.S. Exploring Expedition, pi. li. fig. 604.

1877. Hyalxa minuta, Sowerby, in Reeve, Conchologia. iconica, t. xx., Pteropoda, fig. 9.

1877. Hyalxa intermedia, Sowerby, Ibid., fig. 10.

1879. Hyalxa costata, Pfeffer, Uebersicht der auf S.M. Schiff Gazelle und von Dr. Jagor gesammelten Pteropoden, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1879, p. 234.

For description and figures, see Boas, Spolia atlantica, p. 99, pi. i. fig. 4 ; pi. ii. fig. 15. Habitat. — Atlantic Ocean; from 34° 30' N. to 17° O' S. (Knocker).

Indian Ocean ; from the Gulf of Bengal to the Cape (Pfeffer), from the coasts of Africa (Red Sea, Madagascar, Natal) to Australia. The specimens from the Indian Ocean all belong to the form costata.1

Pacific Ocean ; western portion, Yellow Sea (British Museum), China Sea (Boas), Port Jackson (Angas) ; eastern portion from 36° N. to 28° S. (Knocker).

Challenger Specimens. — I. Living specimens.

Station 175, August 12, 1874 ; Fiji to Raine Island; lat. 19° 2' S.,long. 177° 10' E: Station 181, August 25, 1874 ; Fiji to Raine Island; lat. 13° 50' S., long. 151° 49'E. Station 216a, February 16, 1875 ; north of New Guinea; lat. 2° 56' N., long. 134° 11' E.

1 Pfeffer (Die Pteropoden des Hamburger Museums, Abhandl. Naturw. Ver. Hamburg, t. vii. p. 91) also records the form costata from the Atlantic.

REPORT ON THE PTEROPODA.

79

August — September 1875, Sandwich Islands to Tahiti.

Station 337, March 19, 1876 ; Tristan da Cunha to Ascension Island ; lat. 24° 38' S., long. 13° 36' W.

On April 29, 1876 ; off St. Vincent (Cape Verde) ; lat. 18° 8' N., long. 30° 5' W.

Station 353, May 3, 1876 ; St. Vincent to Azores ; lat. 26° 21' N., long. 33° 37' W.

II. Deposit shells.

Station VIII., February 12, 1873; off Canary Islands; lat. 28° 3' 15" N., long. 17 r 27' 0" W., depth, 620 fathoms; bottom, volcanic mud.

Station 3, February 18, 1873; Tenerife to Sombrero Island; lat. 25° 45' N., long. 20° 14' W.; depth, 1525 fathoms; bottom, hard ground.

Station 23, March 15, 1873 ; off Sombrero Island; lat. 18° 24' N., long. 63° 28' W.; depth, 450 fathoms ; bottom, Pteropod ooze.

Station 24, March 25, 1873 ; off Culebra Island ; lat. 18°