FY (Ne Ne ae 4 es i $7] |\3 Division of Mollusks Sectional Library A) => y { i= “ ZaN A Au ‘te yf Bo i iF View a | vy ‘ a & i; wo PB Yet | a . pe § - ( ’ nip A \ ree ps — . Division of Mo oboe sks @ections! 17 THE tendent of the University Museum of Zoology AND Le i : i creny M.A., Fellow of Christ’s College, Cambridge e Jniversity Lecturer on the Morphology of Invertebrates - VOLUME III SMITHSON Ay MAY 03 1988 LIBRARSS a ce ¢ . < , ay MOLLUSCS © By the Rev. A. H. Cooxg, M.A., Fellow and Tutor of King’s College, Cambridge BRACHIOPODS (RECENT) By A. E. Suietey, M.A., Fellow of Christ’s College, Cambridge , BRACHIOPODS (FOSSIL By F. R. C. Reep, M.A., Trinity College, Cambridge Nes Bork MAZMIEGAN AND CO. — AND LONDON —— 1895 _ All rights reserved cub oe, ms j Map to illustrate THE GEOGRAPHICAL DISTRIBUTION of the LAND OPERCULATE MOLLUSCA The fisures tndicate the ruber of known species J — = — = 150 135 20 105 £ 4 d 16 W.Long: 0.E.Long: 1b London: Macmillan &O° } LSet Mone USCS iy the Rev. A. H. Cane M.A., Fellow and Tutor of King’s College, Cambridge BRACHIOPODS (RECENT) By A. EB. Suirtey, M.A., Fellow of Christ’s College, Cambridge BRACHIOPODS (FOSSIL) By F. R. C. Reep, M.A., Trinity College, Cambridge Nes Work MACMILLAN AND CO. a AND LONDON os 1895 _ All rights reserved “ Why, you might take to some light study: conchology, now; I always think that must be a light study.” GEORGE ELIOT, Aiddlemarch. CopyRIGHT, 1895, By MACMILLAN AND CO. Norwood [press : J. S. Cushing & Co. — Berwick & ‘Smith. Norwood, Mass,, U.S.A. PREFACE TO THE MOLLUSCA THE general plan of classification adopted in this work is not that of any single authority. It has been thought better to adopt the views of recognised leading specialists in the various groups, and thus place before the reader the combined results of recent investigation. This method may, perhaps, occasion a certain number of small discrepancies, but it is believed that the ultimate effect will be to the advantage of the student. The classification adopted for the recent Cephalopoda is that of Hoyle (‘ Challenger’ Reports, Zoology, vol. xvi.), for the fossil Cephalopoda (Nautiloidea) that of Foord (Catalogue of the Fossil Cephalopoda in the British Museum, 1888-91), and (Am- monoidea) P. Fischer (Manuel de Conchyliologie, 1887). In the Gasteropoda the outlines are those adopted by Pelseneer (Mém. Soc. Malacol. Belg. xxvii. 1894), while the details are derived, in the main, from P. Fischer. The Amphineura, how- ever, have not been regarded as a separate class. The grouping of the Nudibranchiata is that of Bergh (Semper, Rezsen im Archipel der Philippinen, ii. 8). The Pelecypoda are classified according to Pelseneer’s most recent grouping. | Acknowledgment of the principal sources of information has been made in footnotes, and a short list of leading author- ities has been appended to the chapters on anatomy, for the use of students desirous to pursue the subject further. In the case % | vi PREFACE of geographical distribution the authorities are too numerous and scattered to admit of a list being given. | A special word of thanks is due to Mr. Edwin Wilson for his patient care in preparing the illustrations, the majority of which are taken from specimens in the University Museum of Zoology. Mr. Edgar Smith, besides affording the kind help which visitors to the British Museum always experience at his hands, has permitted me to use many specimens for the pur- poses of illustration. A. H. COOKE. Kine’s CoLLEGE, CAMBRIDGE, 20th December 1894. CONTENTS ScHEME OF THE CLASSIFICATION ADOPTED IN THIS Boor. MOLLUSCA CHAPTER I INTRODUCTION — POSITION OF MOLLUSCA IN THE ANIMAL KINGDOM — CLASSIFICATION — ORIGIN OF LAND AND FRESH-WATER MOLLUSCA CHAPTER IL LAND AND FRESH-wAaTER MOLLUSCA, THEIR HABITS AND GENERAL Economy : : : ; : : Z ‘ ; ; : CHAPTER II ENEMIES OF THE Moxtuusca — MEANS OF DEFENCE — MIMICRY AND PRo- TECTIVE COLORATION — PARASITIC MoLtiusca — COMMENSALISM — VARIATION . é : ‘ t f ; : : : A CHAPTER. IV Usrs oF SHELLS FoR MoneEy, ORNAMENT, AND Foop — CULTIVATION OF THE OysteER, MussEL, AND Snai~t — Swnaits as MEDICINE — PRICES GIVEN FOR SHELLS ‘ : : : : : E : : - CHAPTER V REPRODUCTION — DEPOSITION OF Eccs — DEVELOPMENT OF THE FERTIL- ISED Ovum — DIFFERENCES OF SEX— DIoEcCIOUS AND HERMAPHRO- DITE Moxiiusca — DEVELOPMENT OF FRESH-WATER BIVALVES . F Vii 23 56 96 123 viii MOLLUSCA CHAPTER VI RESPIRATION AND CIRCULATION —THE MANTLE. Ble : . 150 CHAPTER VI Orcans or SENSE: Toucu, Sicgut, SMELL, HeEaArinc — Tur Foot — THE NERVOUS SYSTEM . A k é : ‘ , : - . ae CHAPTER VIII Tue DIGESTIVE ORGANS, JAW, AND RADULA: EXCRETORY ORGANS ~ 209 CHAPTER IX THE SHELL, ITS Form, Composition, AND GROWTH — DESIGNATION OF ITS VARIOUS PaRTs . 5 < : : é : : : . 244 CHAPTER X GEOGRAPHICAL DISTRIBUTION OF LAND AND FRESH-WATER MOoLLUSCcA — THE PALAEARCTIC, ORIENTAL, AND AUSTRALASIAN REGIONS . - ZF CHAPTER XI GEOGRAPHICAL DistRIBUTION OF Lanp Mo t.vusca (continued) — THE EruHiopiaAn, NEARCTIC, AND NEOTROPICAL REGIONS . : : - 328 CHAPTER XII DisTRIBUTION OF Marine Moxziusca — DeEp-sEA MOLLUSCA AND THEIR CHARACTERISTICS . : 5 B ; . 3 ‘ ‘ : . 3860 CHAPTER XIII Crass CEPHALOPODA . : ‘ ; : : P e ; : . 3878 CONTENTS 1x CHAPTER XIV Crass GASTEROPODA — AMPHINEURA AND PROSOBRANCHIATA . 2 . 400 CHAPTER XV Crass GASTEROPODA (continued): OPISTHOBRANCHIATA AND PuLMonaTA 427 CHAPTER XVI CLAssES SCAPHOPODA AND PELECYPODA . i : A , rs . 444 BRACHIOPODA (RECENT) CHAPTER XVII INTRODUCTION — SHELL — Bopy — DicestiveE System — Bopy Cavity — CIRCULATORY SysTEM— EXcRETORY OrGAaNs — Muscies — NERVOUS System — REPRODUCTIVE SysTEM — EmpryroLtocy — Hasits — Dis- TRIBUTION — CLASSIFICATION : : : é { : : . 463 BRACHIOPODA (FOSSIL) CHAPTER XVII IntTRODUCTION — Division I. Ecarpines — EXTERNAL CHARACTERS — In- TERNAL CHARACTERS — Division II. TEsSTICARDINES — EXTERNAL CHARACTERS — INTERNAL CHARACTERS —SYNOPSIS OF FAMILIES — ' STRATIGRAPHICAL DISTRIBUTION — PHYLOGENY AND ONTOGENY . . 491 SCHEME OF THE CLASSIFICATION ADOPTED IN THIS BOOK MOLLUSCA Class Order- Sub-order of Section s Ocroropa (p. 382). Dibranchi- Phragmophora (p. 386). ata DECeEeoe Sepiophora (p. 388). Myopsidae (p. 389). CEPHALO- Chondrophora } Ojigopsidae (p. 390). PODA Retrosiphonata (p. 393). ah NAUTILOIDEA eae (p. 395). branchiata : Retrosiphonata (p. 397). a Prosiphonata (p. 397). : POLYPLACOPHORA (p. 400). Amphineura a pracopnora (p. 404). (Docoglossa (p. 405). Zygobranchiata (p. DIOTOCARDIA +s 406). BiipiGoelaa4 Azygobranchiata (p. 407). Proso- | Saree Ptenoglossa (p. 411). . Platypoda (p. 411). Taenioglossa MonorocaRDIA 8 Heteropoda (p. 420). Gymnoglossa (p. 422). GASTERO-~° Rachiglossa (p. 422). PODA Toxoglossa (p. 426). Bulloidea (p. 429). TECTI- Aplysioidea (p. 450). BRANCHIATA | Pleurobranchoidea (p. 431). Siphonarioidea (p. 431). Opistho- — ASCOGLOSSA (p. 451). branchiata | Nupt- Cladohepatica (p. 482). BRANCHIATA | Holohepatica (p. 433). Thecosomata (p. 485). Gymnosomata (p. 437). BASOMMATOPHORA (p. 438). STYLOMMATOPHORA (p, 439). PTEROPODA { Pulmonata { SCHEME OF MOLLUSCA AND BRACHIOPODA xl Class Order Sub-order Protobranchiata (p. 447). ANOMIACEA (p. 448). Filibranchiata ARCACEA (p. 448). Myrivacea (p. 448). Pseudolamellibranchiata (p. 449). SUBMYTILACEA (p. 451). PELECYPODA TELLINACEA (p. 453). VENERACEA (p. 454). Eulamellibranchiata CARDIACEA (p. 454). Myacea (p. 456). PHOLADACEA (p. 457). ANATINACEA (p, 458). Septibranchiata (p. 459). BRACHIOPODA Order Family Lingulidae (pp. 487 and 503). Obolidae (p. 504). ECARDINES Discinidae (pp. 487 and 504). Craniidae (pp. 487 and 504). Trimerellidae (p. 504). Productidae (p. 504). ‘ Strophomenidae (p. 505). Ear opoda Koninckinidae (p. 505). Spiriferidae (p. 505). Atrypidae (p. 505). TESTICARDINES Rhynchonellidae (pp. 487 and 505). Terebratulidae (pp. 487 and 506). Argiopidae (p. 506). Stringocephalidae (p. 506). Thecidiidae (pp. 487 and 506). ‘LIST OF MAPS THE GEOGRAPHICAL DISTRIBUTION OF THE LAND OPERCULATE MOLLUSCA Frontispiece THE GEOGRAPHICAL DISTRIBUTION OF THE LAND MOoOLLuUscA OF THE East Indian ARCHIPELAGO . ; : : . Between pp. 308 and 309 THe RELATIONS OF THE LAND Mo.uuusca oF NEw GUINEA WITH THOSE oF NortH AUSTRALIA . - . : : ‘ ; . To face p. 322 THE GEOGRAPHICAL DISTRIBUTION OF THE LAND MOLLUSCA OF THE West Inpixs : ‘ : ; : ‘ . Between pp. 344 and 345 MOLLUSCS REV. A. H. COOKE, M.A. Fellow and Tutor of King’s College, Cambridge CHAPTER I INTRODUCTION — POSITION OF MOLLUSCA IN THE ANIMAL KING- DOM — CLASSIFICATION — ORIGIN OF LAND AND FRESH- WATER MOLLUSCA IT is the generally accepted opinion among men of science that all life originated in the sea. Not that all parts of the sea are equally favourable to the development of forms of life. The ocean surface, with its entire absence of shelter or resting-place, and the deep sea, whose abysses are always dark and cold and changeless, offer little encouragement to plant or animal life, as an original starting-point. True, both the surface and the depths of the sea have become colonised by myriads of forms, Mollusca amongst them, but these quarters are in the truest sense colo- nised, for the ancestors of those who inhabit them in all proba- bility migrated from elsewhere. _____ lt was no doubt the littoral region and the shallow waters _ immediately below it, a region of changeable currents, of light and shade, of variation, within definite limits, of temperature _ and tide effects, which became the scene of the original develop- _ ment of plant life, in other words, of the food-supply which - rendered possible its colonisation by higher animals. But the _ littoral region, besides the advantages of tenancy which it offers to animal life, has also its drawbacks. The violence of the surf may beat its inhabitants in pieces, the retreat of the tide exposes them, not merely to innumerable enemies in the shape of pre- datory birds and beasts, but also to a change in the atmospheric medium by which they are surrounded. Hence, in all proba- _ bility, have arisen the various forms of adaptation which are caleu.uted to bring about the ‘ survival of the fittest’; hence, to VOL. IIl La B 2 VARIETIES OF STATION CHAP. narrow our point of view to the Mouuusca, the development of hard shells, or exoskeletons, hence the sand-burrowing, rock- boring, rock-clinging instincts of various genera and species.! What was the primitive form of molluscan life is little likely to be ever positively known, although, on grounds of comparative anatomy, something approaching to the archi-mollusc is often constructed, with more or less probability, by careful observers. From one of the oldest known geological strata, the Cambrian, nearly four hundred species of Mollusca are known, which include representatives of nearly all the great Orders as they exist at the present day, and without the slightest sign of approximation to one another. With regard to the origin of the land and fresh- water Mollusca some definite conclusions can be arrived at, which will be given in their proper place. | Scarcely any portion of the coast-line of the world is desti- tute of molluscan life, except in regions where extreme cold forbids its existence. Thus along the shores of Northern Asia — there is no proper littoral fauna, the constant influence of travel- ling ice sweeping it all away; animal life begins at about three fathoms. But in every coast region not positively hostile to existence Mollusca make their home. Each description of habitat has its own peculiar species, which there flourish best, and exist precariously, if at all, elsewhere. Thus the sandy waste of estuaries, the loose and shingly beaches, the slimy mud- flats beset with mangroves, the low stretches of jagged rock, and even the precipitous cliffs, from whose base the sea never recedes, have all their own special inhabitants. The same is true of the deep sea, and of the ocean surface. And when we come to examine the land and fresh-water Mollusca, it is found not merely that some Mollusca are terrestrial and others fluvia- tile, but that certain species haunt the ‘hills and others the valleys, some the recesses of woods and others the open meadow sides, some prefer the limestone rocks, others the sandy or clayey districts, some live only in still or gently moving waters, while others are never found except where the current is rapid and powerful. | It is within the tropics that the Mollusca become most nu- merous, and assume their finest and quaintest forms. A tropical beach, especially where there is a good tide-fall and considerable 1 See especially Moseley, Nature, 1885, p. 417. I A TROPICAL eae 3 variety of station, abounds in molluscan life to an extent which must literally be seen to be believed. The beach at Panama, to select an instance familiar to the present writer, is astonishingly rich in species, which probably amount in all to several hundreds. This is due to the immense variety of habitat. On the rocks at high-water mark, and even above them, occur Truncatella, Melampus, Littorina, and Siphonaria ; where a mangrove-swamp replaces the rock, on the branches overhead are huge Littorina, while three species of Cerithidea crawl on the mud, and Cyrena and Area burrow into it. Lower down, in the rock pools at half-tide mark are Cerithium, Purpura, Omphalius, Anachis (2 sp.), Wassa, and several Crepidula. At low-water mark of ordinary tides, under stones half buried in clean sand, are Coecum and Vitrinella ; under the blocks which rest on solid rock are Cypraea (4 or 5 sp.), Cantharus, more Anachis, Columbella (8 sp. including the graceful C. harpiformis), and Nitidella. Where the blocks of rock are rather muddy, Conus lurks, and with it Turritella and Latirus. Where the rocks form a flat-topped platform 2 or 3 feet high, with here and there a deep crack, huge Chitons 3 inches long conceal themselves, with two species of Turbo, Purpura, and Clavella. At extreme low-water mark of spring tides, on the isolated rocks are Monoceros, Leucozonia, and Vermetus, in them are Pholas and a burrowing Mytilus, under them are more Conus, Doliwm, and huge frilled Murices. Patches of clean gravelly sand here produce Strombus ; on the operculum of the great Str. galea is sure to be a Crepidula, exactly fitting its breadth. On the liquid mud-flats to the north glide about Marginella, Nassa, and Trunearia, in the clean sand- stretch to the west Olivella ploughs about by hundreds with several species of Watica, and Tellina and Donaxr bury them- selves deep, while farther down are Artemis, Chione, and, where mud begins to mix with the sand, Mytilus and more Area. Each of these species has its own habitat, often circumscribed to _a few square feet at the most, and it would be utterly useless to seek for it anywhere except in its own special domain. Equally abundant are the land Mollusca of the tropics. Prof. C. B. Adams relates that within the limits of a single parish in Jamaica, named Manchester, which measures no more than four miles long and one mile broad, he obtained no fewer than. one hundred species. Mr. J. S. Gibbons, in a description of 4 LAND MOLLUSCA IN THE ZROPICS CHAP. the Mollusca he obtained near St. Ann’s, Curagao, gives a lively picture of their abundance in an exceptionally favoured locality : —1 ‘Near the outskirts of the town a waste piece of ground supplied me with occupation for all the time I had to spare. Neither grass nor water was to be seen, the only vegetation con- sisting of a few stunted cacti and still fewer acacia bushes. This, however, was so rich in shells that of several species enough specimens could have been collected in a few yards to supply, I should suppose, all the shell cabinets in the world. . . . The stones, plants, and ground were covered with Strophia uva L., Tudora megacheila, P. and M., was in equal abundance, suspended by its silk-like thread from acacia boughs, or strewed thickly on the ground underneath. A Bulimulus (B. multi- lineatus var. sisalensis) abounded on the smaller boughs, while under masses of coral Macroceramus inermis Gundl., Pupa par- raiana d’Orb, and P. pellucida Pfr., were abundant. In the loose soil Cylindrella Raveni Bland, Cistula -Raveni Bland, and a curi- ous Cionella were so numerous that a spade would have been the best instrument with which to collect them. I wasted a good deal of valuable time in separating them from the soil, when by simply taking away a few handfuls of mould, I might have obtained a larger number of specimens. A species of Stenogyra and a Succinea complete a list, all of which might have been gene from almost any square yard of aaa: on the hill- side.” Position of Mollusca in the Animal Kingdom.— Up to very recent times it was usual to regard the Mollusca as one of the four subdivisions of a great family known as Malacozoa, the subdivisions being (1) Mollusca, (2) Tunicata, (8) Brachio- poda, (4) Polyzoa or Bryozoa. This classification is still retained in the leading modern manual on the subject.2 The progress, however, of investigation leads to the belief that the Mollusca are not so closely related to these other groups as such a classi- fication would seem to imply. The Tunicata, for instance, appear, from the whole course of their development, to occupy 1 Quart. Journ. Conch. i. p. 371. 2 Manuel de Conchyliologie et de Paléontologie Conchyliologique. Dr. P. Fischer. Paris, 1887. I POSITION IN ANIMAL KINGDOM 5 a position near to the Vertebrata. The relations of the Brachio- poda and Polyzoa will be more particularly referred to in that part of this History which deals especially with those groups. The position of the Mollusca is, in many respects, one of con- siderable isolation. Any attempt, therefore, definitely to relate them to one group or another, is, in all probability, to go further than the present state of our knowledge warrants. Especially to be deprecated are systems of classification which confidently derive the Mollusca in general from this or that group. The first undisputed traces of animal lfe, which appear in the Cambrian epoch, exhibit the same phyletic distinctions as now exist. Sponges, Kehinoderms, Mollusca, and Worms, formed already, in those immeasurably remote ages, groups apparently as generally distinct from one another as they are at the present time. It would seem that any theory of development, which confidently teaches the derivation of any one of these groups from any other, is, in the present state of the evidence before us, hazardous in the extreme. Some indications of relationship, which must not be pushed too far, may be drawn from a consideration of embryonic re- semblance. An especial characteristic of the Mollusca is the possession of a particular form of larva, which occurs in one of the stages of development, known as the trochosphere (see p. 130). This form of larva is shared with two orders of Anne- lida, the Chaetopoda and the Gephyrea armata, and, in all probability, with the Polyzoaas well. It may also. be significant that the adult form in Rotifera bears a close resemblance to the trochosphere larva in those groups. | Basis of Classification. The Mollusca are divided into four great Orders— Cephalopoda, Gasteropoda, Scaphopoda, _ and Pelecypoda.! Each name, it will be noticed, bears refer- ence to the ‘foot,’ z.e. to the organ of motion which corresponds in function to the foot in the Vertebrata. In the Cephalopoda the feet, or, as they are more frequently termed, the ‘arms,’ are arranged symmetrically round the head ‘or mouth. The common forms of ‘cuttle-fish’ (Octopus, Loligo) are familiar examples of Cephalopods. The Gasteropoda crawl on the flat under-surface or ‘sole’ of lL xepady, head; yaoryp, stomach ; cxdmrev, to dig; médexus, an axe; movs, 7066s, a foot. 6 CLASSIFICATION CHAP..- the foot. Snails, slugs, sea-hares, whelks, periwinkles, and coats- of-mail or chitons are examples of this Order. The Scaphopoda possess a long tubular shell open at both ends; with their small and elongated foot they are supposed to dig into the mud in which they live. The common Dentalium or tusk-shell of our coasts is a representative of this Order. Fie. 1.— Examples of the four Orders: A, Cephalopoda; B, Gasteropoda; C, Scapho- poda, and D, Pelecypoda. A, Ommastrephes sagitta- tus Lam., Naples: a, a, arms surrounding the mouth; /, funnel; ¢, t, the two ‘ten- tacular’ arms. X2%. B, Buc- cinum undatum L., Britain: J, foot; pr, proboscis. x. C, Dentalium entalis L., Norway: /f, foot. D, Car- dium oblongum Chem., Na- ples: jf, foot; s, efferent or anal siphon; s’, efferent or branchial siphon. xX. ek i f) Pe \ SE EZZZ ih) H i SU Ne The Pelecypoda} are enclosed in a bivalve shell fastened by a muscular hinge, the adjacent part of the valves being generally more or less toothed; the foot is as a rule roughly comparable to the shape of an axe-head. To these four Orders is frequently added a fifth, the Ptero- poda, whose exact position is at present not absolutely settled. The Pteropoda? are ‘pelagic,’ z.e. they live in the open waters of the ocean, rising to the surface at night, and sinking into cooler water by day. They are provided with a pair of wing- 1 Also known as Lamellibranchiata, Conchifera, and Acephala. 2 mrepoy, wing. I CLASSIFICATION 7 like appendages or ‘feet,’ on each side of the head, by means of which they are enabled to swim. Some authorities regard the Pteropoda as a subdivision of Gasteropoda, others as form- ing a separate Order, of equivalent value to the other four. The question will be further discussed below (see chap. xv.), but for the present it will be sufficient to state that the weight of evidence appears to show that the Pteropoda are modified Gas- teropoda, with special adaptations to pelagic life, and are there- fore not entitled to rank as a separate Order. Some writers conveniently group together the first three of these Orders, the Cephalopoda, Gasteropoda, and Scaphopoda, under the title Glossophora,! or Mollusca furnished with a radula or ribbon-shaped ‘tongue,’ set with rows of teeth and situated in something of the nature of a head, as distinguished from the Aglossa (or Lipocephala),? t.e. those Mollusca which have no radula and no head. To the latter belong only the fourth Order, the Pelecypoda. ‘This view postulates, for the primitive ancestral Mollusc, a body with a more or less developed head, and possibly the rudiments of an apparatus for grinding or triturating food. This form, it is held, either developed or degenerated. In the former case, in consequence of the more active mode of life upon which it may be supposed to have entered, it gave rise to all the more highly organised forms which are grouped under the three great Orders. When, on the other hand, the ancestral form associated itself with an inactive or sedentary life, it was, we may believe, modified accordingly, and either lost by atrophy or failed to acquire those special points of organisation which characterise the highly-developed form. Hence the Pelecypoda, or bivalves, whose characteristic is the absence of any definite cephalic region or masticatory apparatus. It is a remarkable fact in support of this theory of the origin of the Aglossa that certain of their larvae are known to possess traces of higher organisation, e.g. an external mouth and eyes, the former of which becomes covered by the mantle lobes, while the latter disappear long before the adult stage is reached. 1y\Gooa, tongue; Pépey, to carry. 2 Xelmerv, to be wanting. 8 CLASSIFICATION OF GASTEROPODA CHAP. Thus we have MOLLUSCA MN ieee | | Glossophora Aglossa | Cephalopoda Gasteropoda Scaphopoda Pelecypoda Classification of Gasteropoda.— The Gasteropoda are nu- merically very largely in excess of the two other Orders of the Glossophora, far more complicated as regards classification, and contain a large proportion of those examples of the Mollusca which are most familiar to the ordinary observer. It will there- fore be convenient to postpone for the present a fuller discussion of the subdivisions of the Cephalopoda and Scaphopoda, as well as of the Aglossa, returning to them again in special chapters _ (chaps. xiii. and xvi.), and to devote a few introductory words" to the classification and relations of the Gasteropoda. The Gasteropoda are divided into four Classes, Amphineura, Prosobranchiata, Opisthobranchiata, and Pulmonata. Ste (1) The Amphineura?! are bilaterally symmetrical Mollusca, Fig. 3.—An example of the Aplacophora, Neomenia ca- rinata Tullb.: a, anus; gr, ventral groove; m, mouth. Fig. 2.— An example of the Polyplacophora: Chiton spin- osus Brug. i.e. With organs either single and central, or paired and disposed on either side of the longer axis of the animal. The shell, when 1 dupl, on both sides; vedpov, nerve, vessel. Some authorities regard the Amphineura as a distinct Order. mt _ I il CLASSIFICATION OF GASTEROPODA , 9 present, is es spiral, but consists of eight overlapping plates, kept together by an elliptical girdle. The Amphineura are divided into (a) Polyplacophora,} or Chitons, and (6) Aplacophora (Chaetoderma and Neomenia). (2) The Prosobranchiata? are so named from the fact that the breathing organ (branchia or ctenidium®) is as a rule situated in front of the heart, the auricle at the same time being in front of the ventricle. They are asymmetrical, almost always fur- nished with a shell, which is at some time spiral, and with an operculum. The sexes are separate. They are either marine animals, or can be shown to be more or less directly derived from genera which are marine. They are divided into (a) Diotocardiat (Haliotis, Fissurella, Trochus, Nerita, Patella), which have, or whose immediate ancestors are believed to have had, two auricles to the heart, two sets of breathing organs, two kidneys, but no proboscis, penis, or siphon, and (6) Monotocardia,t in which the heart has only one auricle, the true breathing organ is single, and there isasingle kidney. To this division belong the great majority of marine uni- valve Mollusca, ef Cy- Fic. 4. —Example of a Heteropod, Guraneoe praea, Buccinum, Murex, mediterranea Lam., Naples: a, anus; 67, Littorina, Ianthina, all the banchla: J, foot; 4, intestine: m, mouth land and fresh-water oper- x3. The animal swims foot uppermost. culates (Cyclostoma, Me- lania, Paludina, etc.), as well as the Heteropoda, hich are a group of Prosobranchiata which have betaken themselves to a pelagic life. (8) In the Opisthobranchiata® the breathing organs (when present) are behind the heart, and the auricle of the heart is consequently behind the ventricle. They are asymmetrical marine animals; usually, but by no means always, without a 1 rods, Many; 7ddé, plate. 2 rpocw, in front. Often alluded to in the sequel as ‘ operculate Gasteropoda.’ 3 xrevid.ov, a little comb. ‘4 dvw, two; pwdvos, single ; wra, auricles; xapdla, heart. 5 8ricGev, behind. é ro) CLASSIFICATION OF iat, | aegis: e CHAP. shell, scarcely ever with an operculum in the adult state. The sexes are united in the same individual. The Opisthobranchiata fall into two divisions: (a) Tectibranchiata, in which the breath- ing organ is more or less covered by the mantle, and a shell is usually present, which is sometimes rudimentary, e.g. Bulla, os e Fie. 5.—A, A Tectibran- ie chiate Opisthobranch, Umbrella mediterra- nea Lam., Naples: a, anus; br, branchia; /, foot; m, mouth; rh, rhinophores; sh, shell. B, A Pteropod, Hya- laea tridentata Forsk., Naples: sh, shell; J, 7, swimming lobes of foot. C, A Nudibranchi- ate Opisthobranch, Ae- y olis peregrina, Naples: c br J, foot; c, cerata. “i 6 ji f ) HN ati Via 2 hi Sat Aplysia, Umbrella, and the whole group of Pteropoda; (6) Nudibranchiata, or sea slugs, which have no shell and no true ctenidia, but breathe either by the skin, or by ‘ cerata’ or papill- form organs prominently developed on the back: e.g. Doris, Aeolis, Dendronotus. | (4) The Pulmonata! are asymmetrical air-breathing non- Fic. 6.—Examples of—A, Pulmonata Basommatophora, the common Limnaea peregra Miull.: e,e,eyes; t,t, tentacles. B, Pulmonata Stylommatophora, Helix hortensis Miull.: e, e, eyes; t, t, tentacles; p. 0, pulmonary orifice (the position of the pulmonary orifice in Limnaea will be seen by reference to Fig. 101). marine Mollusca, generally, but not always, furnished with a shell. ‘The sexes are always united in the same individual, and the operculum is always wanting, except in Amphibola. They 1 Pulmo, a lung. I ‘ORIGIN OF THE LAND AND FRESH-WATER MOLLUSCA II are conveniently divided into Stylommatophora,! in which the eyes are at the tip of the upper tentacles, which are retractile (Helix, Limaz, Bulimus, and all true land slugs and snails), and Basommatophora, in which the eyes are at the base of the ten- - tacles, which are not retractile (Limnaea, Planorbis, Physa, and all the Auriculidae). Thus we have : Polyplacophora Amphineura { ‘A piachhels ; . Diotocardia Gasteropoda { nie ee Lien eee om (incl. Heteropoda) Ones . Tectibranchiata (incl. Pteropoda) | Opisthobranchiata eee elenaviaier Stylommatophora Basommatophora The relation of the four great Orders to one another will be better discussed when we come to deal with each Order separately. The problem of the origin and mutual relationship of the various forms of molluscan life is of extreme subtlety, and its solution can only be approached after a comprehensive survey of many complicated anatomical details. But there is one branch of the Mollusca—the land and fresh-water genera — whose origin is, comparatively speaking, of recent date, and whose relationships are therefore less likely to have suffered complete obliteration. Origin of the Land and Fresh-water Mollusca. — The ultimate derivation of the whole of the land and fresh-water molluscan fauna must, as has already been remarked, be looked for in the sea. In certain cases the process of conversion, if it may be so termed, from a marine to a non-marine genus, is still in progress, and can be definitely observed; in others the conversion is complete, but the modification of form has been so slight, or the date of its occurrence so recent, that the con- nexion is unmistakable, or at least highly probable; in others again, the modification has been so great, or the date of its occurrence so remote, that the actual line of derivation is obscured or at best only conjectural. This passage from a marine to a non-marine lfe —in other 1 gridos, pillar; 3upara, eyes. 2 The Ascoglossa are dealt with below (chap. xv.). 12 ORIGIN OF THE LAND AND FRESH-WATER MOLLUSCA cuap. words, this direct derivation of non-marine from marine genera — is illustrated by the faunal phenomena of an inland brackish- water sea like the Caspian, which is known to have been origi- nally in connexion with the Mediterranean, and therefore origi- nally supported a marine fauna. The Mollusca of the Caspian, although without exception brackish- or fresh-water species, are in their general facies distinctly marine. Of the 26 univalve species which inhabit it 19 belong to 4 peculiar genera (Mhero- melania, Caspia, Clessina, Nematurella), all of which are modi- fied forms of the marine fissoidae. The character- istic bivalves belong to the genera Adacna, Didacna, and Monodacna, all of which can be shown to be derived from the common Cardium edule. We have here a case where complete isolation from the sea, com- bined no doubt with a gradual freshening of the Z water, has resulted in the Fie. 7.— A, the common cockle (Cardium development of a number of caus 1), Bs gaara pleata Bier, new genera. Thesingulanly Pall., Caspian Sea. marine facies of several of the fresh-water genera now inhabiting Lake Tanganyika, has given rise to the belief, among some authorities, that that lake was at one time an inlet of the Indian Ocean. In the upper waters of the Baltic, marine and fresh-water Mollusca flourish side by side. So complete is the intermixture, that an observer who had lived on no other shores would probably be unable to separate the one set of species from the other.1. Thus between Dragé and Papenwick? Mytilus edulis, Cardiwm edule, Tellina balthica, Mya arenaria, Littorina rudis, and Hydrobia balthica are the only true marine species ; with these live Unio, Cyclas, Neritina, Limnaea, and Bithynia. The marine species and Neritina live down to 15-20 fath., the SN SO Sol) UN wis 1 Beudant, by very gradually changing the water, accustomed marine species to live in fresh, and fresh-water species to live in salt water. 2 Braun, Arch. f. Naturk. Liv. (2), x. p. 102 f. I EMIGRATION TO LAND AND FRESH WATER 13 rest only down to 38 fath. Under stones close to the shore of the Skirgard at Stockholm! are found young Cardiwm and Tellina, and at 3 to 6 fath. Limnaea peregra, and Physa fontinalis. Near Gothland Limnaea is found in the open sea at 8-12 fath., and with it occur Cardiwm and Tellina. At the Frisches Haff? Mya arenaria is the only marine species, and lives in company with 6 sp. Limnaea, 1 Physa, 9 Planorbis, 1 Ancylus, 4 Valvata, 2 Sphaertum. Were the Sound to become closed, and the waters of the Baltic perfectly fresh, it would be inevitable that Mya arenaria, and such other marine Species as continued to live under their changed conditions, should in course of time submit to modifications similar in kind to those experienced by the quondam marine species of the Caspian. It seems probable, however, that the origin, at least in a ereat part, of the land and fresh-water Mollusca need not be accounted for by such involuntary changes of environment as the enclosure of arms of the sea, or the possible drying up of inland lakes. These cases may be taken as illustrations of the much more gradual processes of nature by which the land and fresh-water fauna must have been developed. The ancestry of that fauna must be looked for, as far as the Gasteropoda are concerned, in the littoral and estuarine species; for the Pelecy- poda, in the estuarine alone. The effect of the recess of the tide, in the one case, and the effect of the reduced percentage of salt, in the other, has tended to produce a gradual adaptation to new surroundings, an adaptation which becomes more and more perfect. It may be safely asserted that no marine species could pass into a land or fresh-water species except after a period, more or less prolonged, of littoral or estuarine existence. Thus we find no land or fresh-water species exhibiting relation- ships with such deep-sea genera as the Volutidae, Cancellariidae, Terebridae, or even with genera trenching on the lowest part of the littoral zone, such as the Haliotidae, Conidae, Olividae, Capulidae. The signs of connexion are rather with the Neritidae, Cerithiidae, and above all the Littorinidae, which are accustomed to live for hours, and in the case of Littorina for days or even weeks, without being moistened by the tide. Similarly the 1 Lindstrém, Oef. K. Vet. Forh. Stockh., 1855, p. 49. 2 Mendthal, Schr. Ges. Konigsb., xxx. p. 27. 14. ORIGIN OF FRESH-WATER BIVALVES CHAP, fresh-water Pelecypoda exhibit relationships, not with genera exclusively marine, but with genera known to inhabit estuaries, such as the Mytilidae, Corbulidae, Cardicdae. It would be natural to expect that we should find this process of conversion still going on, and that we should be able to detect particular species or groups of species in process of emigration from sea to land, or from sea to fresh water. Such species will be intermediate between a marine and a land or fresh-water species, and difficult to classify distinctly as one or the other. Cases of Mollusca occupying this interme- diate position occur all over the world. They inhabit brackish swamps, damp places at high-water mark, and rocks only at intervals visited by the tide. Such are Potamides, Assiminea, Siphonaria, Melampus, Hydrobia, Truncatella, among the uni- valves, and many species of Cyrena and Area among the bivalves. Origin of the Fresh-water Fauna (a) Pelecypoda.— Estuarine species, which have become accustomed to a certain admixture of fresh water, have gradu- ally ascended the streams or been cut off from the sea, and have at last become habituated to water which is perfectly fresh. Fic. 9.—A, Arca navicella Reeve, Philippines, a marine species. B, Fic. 8.—A, The common Mytilus edulis Arca (Scaphula) pinna Bens., R. L., a marine genus and species. B, Tenasserim, a fresh-water species Dreissensia, a fresh-water genus, closely which lives many miles above the allied to Mytilus. tide-way. Thus Dreissensia (rivers and canals throughout N. Europe and N. America) and Mytilopsis (rivers of America) are scarcely modified Mytili (Fig. 8); Scaphula is a modified Arca, I ORIGIN OF FRESH-WATER BIVALVES I5 and lives in the Ganges, the Jumna, and the Tenasserim at a distance of 1600 miles from the sea (Fig. 9). Pholas rivicola is found imbedded in floating wood on the R. Pantai many miles from its mouth. Cyrena, Corbicula, and probably Sphae- rium and Pisidium are derived, in different degrees of removal, from the exclusively marine Veneridae ; Potamomya (rivers of S. America), and Himella (R. Amazon) are forms of Corbula. The Caspian genera derived from Cardiuwm (Adacna, Didacna, Monodacna), have already been referred to. Mausitora is a form of Yeredo, which lives in fresh water in Bengal. Rangia, Fischeria, and Galatea probably share the derivation of the Cyrenidae, while in Iphigenia we have one of the Donacidae which has not yet mounted rivers, but is confined to a strictly estuarine life. The familiar Scrobicularia piperata of our own estuaries is a Yellina, which lives by preference in brackish water. The great family of the Unionidae is regarded by Neumayr! as derived from TYrigonia, the points of ‘similarity being the development of a nacreous shell, the presence of a strong epidermis, and the arrangement of the muscular scars. It is remarkable, too, that on many Uniones of Pliocene times there is found shell ornamentation of such a type as occurs elsewhere among the Pelecypoda only on Trigonia. The genera of fresh-water Pelecypoda Bare comparatively few in number, and F1¢. 10.—Trigonia pec- : Sa z ; tinata Lam., Sydney, their origin is far more clearly discernible N.S.W. than that of any other group. This is perhaps due to the fact that the essential changes of structure required to convert a marine into a fresh-water bivalve are but slight. Both animals “breathe water,” and both obtain their nutriment from matter contained in water. Similar remarks apply to fresh-water operculate Gasteropoda. But the passage from a marine to an aerial life involves much profounder changes of environment, which have to be met by correspondingly im- portant changes in the organism. This may be in part the 1 SB. K. Akad. Wiss. Wien, 1889, p. 4, but the view is not universally accepted. 16 ORIGIN OF FRESH-WATER UNIVALVES CHAP. reason why the ancestry of all Pulmonata, whether land or fresh- water, is so difficult to trace. (b) Gasteropoda.— (1) Operculate. Canidia and Clea are closely allied, with but ttle modification, to the marine Cominella! (Fig. 11), as is also Nassodonta to Nassa. ‘They occur (in fresh water) in the rivers of India, Indo-China, Java, and Borneo, associated with essentially fresh- water species. -Potamides, with its various oy : subgenera (Telescoprum, Pyrazus, Pirenella, Fic. 11.—A, Cominella, eis : : . a marine genus, Certthidea, etc.), all of which inhabit swamps which lives between and mudflats just above high-water mark in all tide marks,and from 3 : ee which is probably Warm countries, are derived from Cerithiwm derived B, Clea, a (Rig. 12); Assiminea, Hydrobia, and perhaps genusoccurring only ; 5 fi fecal water! Truncatella, from Rissoa. It is a remarkable fact that in Geomelania (with its subgenera Chittya and Blandiella) we have a form of Truncatella which Fic. 12.— A, Cerithium columna Sowb. (marine). B, Potamides microptera Kien. (brackish water). C, Jo spinosa Lea, one of the Pleuroceridae (fresh water). has entirely deserted the neighbourhood of the sea, and lives in woody mountainous localities in certain of the West Indies. Oremnoconchus, a remarkable shell occurring only on wet cliffs in the ghats of southern India, is a modified Littorina. Neritina and Nerita form a very interesting’ case in illustration of the whole process. Werita is a purely marine genus, occurring on rocks in the littoral zone: one species, however, (WV. lineata, 1 Not to Nassa, as has been generally held. The shape of the operculum, and particularly the teeth of the radula, show a much closer connexion with Cominella. I ORIGIN OF FRESH-WATER UNIVALVES 7 Chem.) ascends rivers as far as 25 miles from their mouth, and others haunt marshes of brackish water. Neritina is the fresh- water form, some species of which are found in brackish swamps or even creeping on wet mud between tide marks, while the great majority are fluviatile, one group (Werttodryas) actually occurring in the Philippines on trees of some height, at a dis- tance of a quarter of a mile from any water. Wavicella is a still further modified form of Neritina, occurring only on wet rocks, branches, etc., in non-tidal streams (Fig. 13). Fic. 13.— Illustrating the development of the fresh-water genus Navicella, through the brackish-water Veritina, from the marine Vervita, with corresponding changes in the operculum. 1. Nerita; 2,3. Neritina; 4. Neritina, intermediate form ; 5, 6. Navicella. si The great family of the Melaniidae, which occurs in the rivers of warm countries all over the world, and that of the Pleuroceridae, which is confined to North America, are, in all probability, derived from some form or forms of Cerithium. The origin of the Paludinidae, Valvatidae, and Ampullariidae is more doubtful. Their migration from the sea was probably of an early date, since the first traces of all three appear in the lower Cretaceous, while Melaniidae are not known until Tertiary times. Ampullaria, however, shows distinct signs of relation- ship to Watica, while the affinities of Paludina and Valvata can- not as yet be approximately affirmed. (2) Pulmonata.— Intermediate between the essentially fresh- water and the essentially marine species come the group some- times known as Gehydrophila, consisting of the two families Auriculidae and Otinidae. These may be regarded as Mollusca which, though definitely removed from all marine species by the development of a true lung or lung cavity in the place of a gill, VOL. III Cc 18 INTERMEDIATE FORMS CHAP. have yet never become, in respect of habitat, genuine fresh- water species. Like Potamides, they haunt salt marshes, man- grove swamps, and the region about high-water mark. In some cases ( Otina, Melampus, Pedipes) they live on rocks which are moistened, or even bathed by the spray, in others (Cassidula, Auri- cula) they are immersed in some depth of brackish water at high tide, in others again (Scarabus) they are more definitely terres- trial, and live under dead leaves in woods at some little distance Fic. 14.— Examples of the Auwriculi- from water. Indeed one genus of dae: A, Auricula Judae Lam., Bor- diminutive size (Carychium) has neo ; B, Scarabus Lessoni Blainv., completely abandoned the neigh- E. Indies ; C, Cassidula mustelina Desh., N. Zealand ; D, Melampus bourhood of the sea, and inhabits | castaneus Mihlf., S. Pacific; E, Pedipes quadridens Ptr., Jamaica. Swampy ground almost all over the world. To this same section Gehydrophila have been assigned two remarkable forms of air-breathing “limpet,” Svphonaria and Gadinia (see page 151), and the aberrant Amphibola, a unique instance of a true operculated pulmonate. Stpho- naria possesses a pulmonary cavity as well as a gill, while Gadinia and Amphibola are ex- gf clusively air-breathing. Stphonaria lives on § rocks at or above high-water mark, Gadinia between tide marks, Amphibola (Fig. 15) in brackish water at the estuaries of rivers, half ee * Pac . ° + Lo. exam- buried in the sand. There can be little doubt ple of Amphibola that all these are marine forms which are ine oe eee gradually becoming accustomed to a terrestrial monate which pos- existence. In Gadinia and Amphibola the pro- 57° ®™ SPEntik cess is so far complete that they have ex- changed gills for a pulmonary cavity, while in S’phonaria we have an intermediate stage in which both organs exist together. A curious parallel to this is found in the case of Ampullaria, which is furnished with two gills and a pulmonary chamber, and breathes indifferently air and water. It is a little 1 AFFINITIES OF THE LIMNAEIDAE I9 remarkable that Stphonaria, which lives at a higher tide level than Gadinia, should retain the gill, while Gadinia has lost it. The ultimate affinities of the essentially fresh-water groups, Limnaea, Physa, Chilina, cannot be precisely affirmed. The form of shell in Latia, Gundlachia, and perhaps Ancylus, may suggest to some a connexion with the Otinidae, and in Chilina, a similar connexion with the Auriculidae. But, in a question of derivation, similarities of shell alone are of little value. It is not a little remarkable, for instance, that we should find a simple patelliform shell in genera so completely distinct from one another in all anatomical essentials as Ancylus, Patella, Siphonaria, Propilidium, Hipponyx, Cocculina, and Umbrella. Some recent authors, on grounds of general organisation, regard the Limnaeidae and their allies as Opisthobranchs adapted to an aerial life. It is held! that the Nudibranchiate Opistho- branchs have given birth to the Pulmonata Stylommatophora or land snails, and the Tectibranchiate Opisthobranchs to the Pulmonata Basommatophora or fresh-water snails. Such a view seems at first sight open to some objection from other views than those which deal simply with anatomy. The Opis- thobranchiata are not, to any marked extent, littoral genera, nor do they specially haunt the mouths of rivers. On the contrary, they inhabit, as a rule, only the very lowest part of the littoral zone, and are seldom found, except where the water is purely salt. In other cases, when the derivation of land or fresh-water genera is fairly well established, intermediate forms persist, which indicate, with more or less clearness, the lines along which modification has proceeded. It has, however, recently been shown that Siphonaria? and Gadinia,? which have, as has been already mentioned, hitherto been classified as Pulmonata, are in reality modified forms of Opisthobranchiata, which are in process of adaptation to a life partly marine, partly on land. They may therefore be regarded as supplying the link, hitherto missing, between the land Pulmonata and the marine groups from one or other of which the latter must have been derived. The general consensus of recent opinion inclines towards accept- ing these views, some writers* being content to regard the 1 #.g. Bouvier, Le Natural, 1889, p. 242. 2 Kohler, Zool. Jahrb. vii. 1893, p.1f£; Haller, Ard. Tape Inst. Wien, x. p. 71. 3 Plate, SB. kén. Preuss. Ak. Wiss. Bert. 1893, p. 959. 4 H.g. Pelseneer, Bull. Sc. France Belg. xxiv. p. 347 f. 20 ORIGIN OF LAND OPERCULATES CHAP. Pulmonata, as a whole, as derived from the Tectibranehie | Opisthobranchs, while others! go further and regard the Stylom- . matophora as derived directly from the Basommatophora. Origin of the Land Fauna Gasteropoda.— (1) Operculate. On a priori grounds, one might predict a double origin for land operculates. Marine species might be imagined to accustom themselves to a terres- trial existence, after a period, more or less prolonged, of littoral probation. Or again, fresh-water species, themselves ultimately derived from the sea, might submit to a similar transformation, after a preliminary or intermediate stage of life on mudbanks, wet swamps, branches overhanging the water, etc. Two great families in this group, and two only, seem to have undergone these transformations, the Littorinidae and the Neritidae. The derivation of almost all existing land operculates may be referred to one or other of these groups. Fic. 16.— Two rows of the radula of Littorina littorea L., X 72. The power of the Littorinidae to live for days or even weeks without being moistened by the sea may be verified by the most casual observer. In the tropics this power seems even greater than on our own shores. I have seen, in various parts of Jamaica, Littorina muricata living at the top of low cliffs among grass and herbage. At Panama I have taken three large species of Littorina (varia, fasciata, pulechra), on trees at and above high-water mark. Cases have been recorded in which a number of L. muricata, collected and put aside, have lived for three months, and ZL. irrorata for four months.2 These facts are significant, when we know that the land operculates almost certainly originated in a tropical climate. 1 #.g. Bergh, Zool. Jahrb. v. p. 1 f. 2 Calkins, Amer. Nat. xi. p. 687. I ORIGIN OF LAND OPERCULATES 2I The Cyclophoridae, Cyclostomatidae, and Aciculidae, which, as contrasted with the other land operculates, form one group, have very close relations, particularly in the length and forma- tion of the radula, or lingual ribbon, with the Littorinidae. Fic. 17. — Two rows of the radula of Cyclophorus sp., India, x 40. Qn the other hand, the Helicinidae, Hydrocenidae, and Pro- serpinidae are equally closely related to Neritina. The Pro- serpinidae (restricted to the Greater Antilles, Central America and Venezuela) may perhaps be regarded as the ultimate term of the series. They have lost the characteristic operculum, which in their case is replaced by a number of folds or lamellae in the interior of the shell. It has already been noticed how one group of Neritina (Neritodryas) occurs normally out of the water. This group furnishes a link between the fresh-water and land forms. It is interesting to notice that here we have the most perfect sequence of derivatives; (Verita in the main a Fig. 18.—A, Neritina reticularis Sowb., Calcutta (brackish water); B, Helicina neritella Lam., Jamaica (land); C, Proserpina (Ceres) eolina Ducl., Central America (land). purely marine form, with certain species occurring also in brackish water; Veritina in the main fresh-water, but some Species occurring on the muddy shore, others on dry land; Helicina the developed land form; and finally Proserpina, an _ aberrant derivative which has lost the operculum. 1 One step even further (or perhaps it should be termed a branch derivative) is seen in the genus Smaragdia, which is probably a Neritina which has re- sumed a purely marine habit of life. 22 ORIGIN OF LAND PULMONATA | CHAP. I Gasteropoda. — (2) Pulmonata. The origin of these, the bulk of the land fauna, must at present be regarded as a problem not yet finally solved. Some authorities, as we have seen, regard them as derived from the Nudibranchiate, others, probably more correctly, from the Tectibranchiate Opisthobranchs. The first known members of the land Pulmonata (Pupa [?], — Hyalinia) are from the Carboniferous of North America. Similar but new forms appear in the Cretaceous, from which time to the present we have an unbroken series. The characteristically modern forms, according to Simroth,! are Helices with thick shells. According to the same author, Vitrina and Hyalinia are ancestral types, which give origin not only to many modern genera with shells, but to many shell-less genera also, e.g. Testa- cella is probably derived through Daudebardia from Hyalinia, while from Vitrina came Limax and Amalia. A consideration of the radulae of the genera concerned certainly tends in favour of these views. Godwin-Austen, speaking generally, considers? genera of land Pulmonata with strongly developed mantle-lobes and rudi- mentary shell as more advanced in development than genera in which the shell is large and covers all or nearly all the animal. 1 §B. Naturf. Gesell. Leipz. 1886-87, pp. 40-48. 2DT.and F. W. Moll. of India, iv. p. 167. CHAPTER II LAND AND FRESH-WATER MOLLUSCA, THEIR HABITS AND GENERAL ECONOMY THE majority of the Land Mollusca are probably more sensi- tive than is usually believed. The humidity of the air must affect the surface of their skin to a considerable extent. Every one has noticed how the snails ‘come out’ on a damp evening, especially after rain. As a rule, they wait till rain is over, probably objecting to the patter of the drops upon their delicate tentacles. Snails kept in captivity under a bell-glass are acutely sensitive of a damp atmosphere, and will bestir themselves after rain just as if they were in the open air. Certain Helices which are accustomed to live in moist places, will find their way to water, if removed from their usual haunts. A case is recorded! of a specimen of H. arbustorum, kept in a kitchen, which used to find its way directly under the cold water tap, and appeared to enjoy the luxury of a douche. How delicately the conditions of life are balanced in some of these creatures is seen in the case of Omalonyz, a genus akin to Succinea, which is found in Brazil and the northern parts of South America. It lives creeping on plants which overhang the margin of water, but perishes equally, if placed in the water itself, or removed to a distance from it for any length of time.? Endurance of Heat and Cold. — The Mollusca are capable, at least as far as some species are concerned, of enduring severe extremes both of cold and heat. The most northern pulmonate yet observed is a fresh-water species, Physa (Aplecta) hypnorum L. This hardy mollusc, whose shell is so fragile as to need most eareful handling, has been noticed on the peninsula of Taimyr, North Siberia, in 73° 30’ N. lat., a region whose mean annual 1T. Scott, Journ. of Conch. v. p. 230. 2 J. S. Gibbons, ibid. ii. p. 129. 22 a 24 HABITS OF LAND MOLLUSCA CHAP, temperature is below 10° F. with a range of from 40° F. in July to —80° F. in January. It is well known that the Limnaeidae, and probably most fresh-water Mollusca of sub-temperate regions, can continue to live not merely under, but enveloped in ice, and themselves frozen hard. Garnier relates! that, during the winter of 1829- 30, some large Limnaea auricularia, which had been placed in a small basin, were frozen into a solid mass, experiencing a cold of —2° F. He supposed they were dead, but, to his surprise, when the basin thawed, the Limnaea gradually revived. Palu- dina vivipara and Anodonta anatina have been known to resist a temperature of 23° F., and the former has produced young shortly after being thawed out of the ice. As far north as Bodé in Norway (67° 37’ N. lat., well within the Arctic circle) there are found no less than fourteen species of terrestrial Mollusca, among them being Balea perversa and Clausilia rugosa Vitrina is one of our most hardy molluscs, and may be observed crawling on bright mornings over the frost-covered leaves of a wood or copse. V. glacialis is said by Charpentier to live in the Alps at a height where the stones are covered with snow from nine to ten months of the year. Many of the Hya- liniae are very hardy. Arion, in spite of having no external shell to protect it, is apparently less affected by the cold than Helix, and does not commence hibernation till a later period in the autumn. ‘The operculate land Mollusca, in spite of the pro- tection which their operculum may be supposed to afford, are exceedingly sensitive to cold, and the whole group is without doubt a product of tropical or semi-tropical regions (see map at | frontispiece). A species of Helicina which inhabits the southern States of North America has been known to be almost extermi- nated from certain districts by the occurrence of an unusually severe winter. One of the highest altitudes at which a land shell is known to live appears to be the Liti Pass (Himalayas, 14,000 ft.). At this enormous altitude, two species of Buliminus (arcuatus Hutt. and nivicola Bens.) live on juniper bushes among patches of snow. An Anadenus is said to have been found in a similar 1 Bull. Soc. Linn. Nord, Abbeville, 1840, p. 150. 2 Joly, Comptes Rendus, 1842, p. 460 ; compare W. A. Gain, Science Gossip, xxvii. p. 118. 3 Von Martens, SB. Nat. Fr. Berl. 1881, p. 34. II ENDURANCE OF HEAT AND COLD 25 locality at 15,000 ft., while Limnaea Hookert has been taken from over 16,400 ft.in Landour. In the Andes of Peru and Bolivia, five species of Bulimulus, one of Pupa, and one of LTimaz occur at an elevation of 10,500 to 15,000 ft. Several fresh-water Mollusca inhabit Lake Titicaca, which stands at a height of 12,550 ft. in the Bolivian table-land. In certain parts of the desert of Algeria, where there is not a trace of vegetation to be seen, and the temperature at mid-day is 110° F., the ground is sometimes so covered with Helix lactea as to appear perfectly white. Dr. F. H. H. Guillemard has told me that he noticed, in somewhat similar surroundings between Fez and Tangier, H. pisana in such extraordinary abundance that they hung from the low scrub in bunches the size of a man’s two fists. It is singular that Mollusca should live, and not only live, but flourish, in localities apparently so unpromising. Shells which occur in the Algerian Sahara are actually larger and altogether finer than the ordinary European form of the same species. In order to protect themselves to some extent against the scorching heat and consequent evaporation, desert species are frequently modified in one of two ways; the shell becomes either white or a light dusky brown, as in the familiar Helix desertorum, or else it gains immensely in thickness. Speci- mens of H. pomatia, recently procured from Fez, are of extraor- dinary thickness as compared with forms from our own chalk downs of Kent and Surrey. Fresh-water Mollusca are frequently found inhabiting hot springs. Thus Neritina fluviatilis lives at Bagnéres de Bigorre in water at about 68° F. In another hot spring in the eastern Pyrenees a Bithynia lives at a temperature of over 73° F.; while Blainville mentions another case of a Bithynia living in water at 122° F. Hibernation and Aestivation. — As autumn begins to draw on, and the first frosts to nip vegetation, terrestrial species retire beneath stones, into cracks in old walls, holes in tree trunks, deep fissures in rocks, and nooks and crannies of every kind, or else bury themselves deeply in the earth or in moss and heaps of leaves. They thus commence their period of hibernation, which varies in length according to the duration of winter. Frequently masses of Helices may be found attached to one another, probably not so much for the sake of warmth, for their 26 HIBERNATION AND AESTIVATION CHAP. temperature is but low, as to share the comforts of a cosy retreat in common. Slugs generally hibernate alone, excavating a sort of nest in the earth, in which they encyst themselves, con- tracting their bodies until they are almost round, and secreting a covering of their own slime. The Helices usually close up the mouth of their shell by the formation of a membranous or chalky epiphragm, which will be further described below. Both snails and slugs take care to be in good condition at the time their winter sleep begins, and for this reason the former are said to be most esteemed by foreign epicures if captured just at this period.1 During hibernation, the action of the heart in land Pulmo- nata ceases almost entirely. ‘This appears to be directly due to the effect of cold. Mr. C. Ashford has related ? some interest- ing experiments made upon #. hortensis and Hyal. cellaria, with the view of ascertaining the effect of cold upon their pulsations. His observations may be tabulated as follows : — Number of pulsations per minute ——Ee Helix hortensis Hyal. cellaria At degrees Fahr. 22 21 52° 14 12 44° 10 11 38° 4 9 30° At low temperatures the character, as well as the number of the pulsations changed; they became imperfect and intermittent, although exceptionally at 31° F. a H. rufescens gave five or six pulsations a minute, very full and deliberate. The result of taking the Hyalinia suddenly into the heat of a greenhouse was to bring on palpitations. Further experiments resulted in evidence of a similar kind. Ayal. radiatula, placed upon a deal table in a room, showed 52 pulsations per minute at 62° F. Placed upon the palm of the hand, the action soon rose to 108. Hyal. alliaria, similarly treated, rose from 72 pulsations to 110. Floated upon water, the action of the heart of the latter sud- denly fell to 29. Fresh-water Pulmonata do not appear to hibernate. Unio and Anodonta, however, bury themselves more deeply in the mud, and Dreissensia casts off its byssus and retires under the 1 Moquin-Tandon, Moll. de France, i. p. 116. 2 Journ. of Conch. iii. p. 821 f.; iv. p. 18; Science Goss. 1866, p. 158. II EFFECTS OF COLD AND HEAT 27 mud in deeper water! Limnaea and Planorbis have often been noticed to crawl about under the lower surface of a thick coat- ing of ice. In periods of prolonged drought, when the water in the ponds dries up, the majority of genera bury themselves in the mud. I have known Limnaea peregra bury itself three inches deep, when surprised by a sudden fall of the water in the ditch on Coe Fen, behind Peterhouse, Cambridge. Physa hypnorum frequents by preference ditches which dry up in sum- mer, as does also Planorbis spirorbis, the latter often forming a sort of epiphragm against evaporation. Ancylus has been ob- served to spend the whole winter out of water, and P. spirorbis has been noticed alive after four months’ desiccation.? True aestivation, however, occurs mainly in the tropics, where there is no winter, but only a period when it is not quite so hot as the rest of the year, or on a coast like the Mediter- ranean, which is subject to sudden and severe heat. This period is usually rainless, and the heat is therefore a dry heat. At this season, which may last for three or four months, most of the land Mollusca enter upon a period of inaction, either burying themselves deeply in the ground, or else permanently attaching themselves to the stalks of grass and other herbage, or the under sides of rocks. For instance, the large and beautifully painted Orthalicus, Corona, and Porphyrobaphe, which inhabit Brazil, —— Ecuador, and eastern Peru, bury themselves deeply in the _. ground during the dry season, while in the rains they climb to the topmost branches of the great forest trees.2 Thus it may well happen that a visitor to a tropical island, Ceylon for in- stance, or one of the Greater Antilles, if he time his visit to coincide with the rainless season, may be grievously disap- pointed at what seems its unaccountable poverty in land Mol- lusca. But as soon as the weather breaks, and the moisture penetrates their retreats, every bush and every stone, in favoured localities, will be alive with interesting species. The Epiphragm. — A considerable number of the land Pul- monata (and a very few of the fresh-water) possess the power of closing the aperture of their shell by means of what is known as an epiphragm or covering of hardened mucus. This epi- phragm is habitually formed by certain species during hiberna- 1 Reichel, Zool. Anz. x. p. 488. 2 Schumann, Schr. Ges. Danz. (2) vi. p. 159. 8 Fischer and Crosse, Mexico, p. 437. 28 THE EPIPHRAGM CHAP. tion or aestivation, or even during shorter periods of inactivity and retirement, the object being, either to check evaporation of the moisture of the body, or to secure the animal against the cold by retaining a thin layer of slightly warm air immediately within the aperture of the shell. The epiphragm differs widely in character in different spe- cies, sometimes (Clausilia, Pupa, Planorbis) consisting of the merest pellicle of transparent membrane, while at others (Helix aperta, H. pomatia) it is a thick chalky substance, with a con- siderable admixture of carbonate of lime, with the consistency of a hardened layer of plaster of Paris. Within these extremes every variety of thickness, solidity, and transparency occurs. During long hibernation several epiphragms are not unfre- quently formed by the same individual snail, one within the other, at gradually lessening distances. The epiphragm thus performs, to a certain extent, the part of an operculum, but it must be remembered that it differs radically from an operculum physiologically, in being only a temporary secretion, while the operculum is actually a living part of the animal. The actual mode of formation of the epiphragm would seem to differ in different species. According to Fischer,! the mol- lusc withdraws into its shell, completely blocking all passage of air into the interior, and closing the pulmonary orifice. Then, from the middle part of the foot, which is held exactly at the same plane as the aperture, is slowly secreted a transparent pellicle, which gradually thickens, and in certain species be- comes calcareous. Dr. Binney, who kept a large number of Helix hortensis in confinement, had frequently an opportunity of noticing the manner in which the epiphragm was formed.? - The aperture of the shell being upward, and the collar of the animal having been brought to a level with it, a quantity of gelatinous matter is thrown out [? where from]. ‘The pulmo- nary orifice is then opened, and a portion of the air within suddenly ejected, with such force as to separate the viscid mat- ~ ter from the collar, and to project it, like a bubble of air, from the aperture. The animal then quickly withdraws farther into the shell, and the pressure of the external air forces back the vesicle to a level with the aperture, when it hardens and forms 1 Journ. de Conch. iv. p. 397, but the species observed is not mentioned. 2 Bull. Mus. C. Z. Harv. iv. p, 378, II SPINNING OF THREADS 29 the epiphragm. In some of the European species in which the gelatinous secretion contains more carbonate of lime, solidi- fication seems to take place at the moment when the air is expelled, and the epiphragm in these is in consequence strongly convex. Thread-spinning.— A considerable number of fresh-water Mollusca possess the power of stretching a thread, which is no more than an exceedingly elongated piece of mucus, to the sur- face of the water, and of using it as a means of locomotion. This thread bears no analogy whatever to the fibrous byssus of certain bivalves, being formed in an entirely different manner, without the need of a special gland. - The threads are ‘spun’ by several species of Limnaea, Physa, and Planorbis, by Bithynia tentaculata, and several of the Cycladidae. ‘They are anchored to the surface by a minute concavity at the upper end, which appears to act like a small boat in keeping the thread steady. The longest threads are those of the Physae, which have been noticed to attain a length, in confinement, of 14 inches. They are always spun in the ascent, and as a rule, when the animal descends, it rolls the thread up and carries it down as it goes. A single thread is never spun on the descent, but occasionally, when a thread has become more or less of a permanence, it becomes stronger by the addition of more mucus each time it is used, whether for as- cending or descending purposes. Cyelas cornea appears to be an exception to the rule that threads are only spun on the ascent. This species, which is particularly fond of crawling along the under surface of the water, has been noticed to spin a thread half an inch in length while on the surface, and to hang sus- pended from it for a considerable time. What the exact use of the thread may be, must to a certain extent be matter of conjecture. The Limnaeidae are, in the great majority of cases, compelled to make periodic visits to the surface in order to inspire oxygen. It is also a favourite habit with them to float just under the surface, or crawl about on its under side, perhaps in pursuit of tiny vegetable organisms. Whatever may be the object of an excursion to the surface, a taut thread will obviously be a nearer way up than any other which is likely to present itself; indeed, without this thread- Spinning power, which insures a tolerably rapid arrival at the 30 USE OF THREADS CHAP. surface, the animal might find itself asphyxiated, or at least seriously inconvenienced, before it could succeed in taking in the desired supply of oxygen. With the Cycladidae, which do not breathe air, such an explanation is out of place; in their case the thread seems to be a convenient means of resting in one position in the intervals of the periods of active exercise to which several of the species are so much addicted. The power of suspension by a thread is also possessed by cer- tain of the Cyclostomatidae, by some Cerithidea, several Rissoa and other marine genera, prominent among which is Litiopa bombyx, whose name expresses its power of anchoring itself to the Sargasso weed by a silken thread of mucus. Several species of slugs are known to be able to let themselves down by threads from the branches of trees. Limazx arborum is especially noted for this property, and has been observed suspended in pairs during the breeding time. According to Binney, all the Ameri- can species of Limaz, besides those of Tebennophorus, possess this singular property. imax arborum appears to be the only slug which has been noticed to ascend, as well as descend, its thread. It has also been observed! that when this species is gorged with food, its slime is thin and watery, and unable to sustain its weight, but that after the process of digestion has been performed, the mucus again becomes thick and tenacious. It appears therefore that when the animal is hungry and most in need of the power of making distant excursions in search of food, its condition enables it to do so, but that when no such neces- sity is pressing, the thread-forming mucus is not secreted, or is perhaps held in suspense while the glands assist in lubricating the food before digestion.? Food of Land and Fresh-water Mollusca. — Arion ater, the great black slug, although normally frugivorous, is unques- tionably carnivorous as well, feeding on all sorts of animal mat- ter, whether decaying, freshly killed, or even in a living state. It is frequently noticed feeding on earthworms; kept in cap- tivity, it will eat raw beef; it does not disdain the carcases of its own dead brethren. An old man near Berwick-on-Tweed, going out one morning to mow grass, found a black slug devour- ing, as he supposed, a dead mouse. Being of an inquisitive 1 'W. Harte, Proc. Dubl. N. H. Soc. iv. p. 182. 2 See on the whole subject of threads G. S. Tye, Journ. of Conch. i. p. 401. 11 FOOD OF SLUGS 31 turn, and wishing to ascertain if it were really thus engaged, he drew the mouse a little back. When he returned in the even- ing, the mouse was reduced almost to a skeleton, and the slug was still there. Indeed it would seem almost difficult to name anything which Arion ater will not eat.) Dr. Gray mentions? a case of a specimen which devoured sand recently taken from the beach, which contained just enough animal matter to render it luminous when trodden on in the dark; after a little time the faeces of the slug were composed of pure sand, united together by a little mucus. | A specimen kept two days in captivity was turned out on a newspaper, and commenced at once to devour it. The same specimen ate dead bodies of five other species of slugs, a dead Unio, pupae of Adimonia tanacett, part of the abdomen of a dragon-fly, and Pears’ soap, the latter reluctantly.® According to Simroth* and Scharff® the food of several of our British slugs, e.g. Limax maximus, L. flavus, Arion subfuscus, A. intermedius, consists of non-chlorophyllaceous substances only, while anything containing chlorophyll is as a rule refused. On the other hand L. agrestis and Amalia carinata feed almost entirely on green food, and are most destructive in gardens. The latter species lives several inches under ground during the day, and comes to the surface only at night. It is largely responsible for the disappearance of bulbs, to which it is ex- tremely partial. L. marginatus (=arborum Bouch.) feeds ex- clusively on lichens, and in captivity absolutely refuses green leaves and a flesh diet. It follows therefore, if these observa- tions are correct, that the popular notions about slugs must be revised, and that while we continue to exterminate from our gardens those species which have a taste for chlorophyll, we ought to spare, if not encourage those whose tastes lie in the opposite direction. Limaz agrestis has been seen patie the crushed remains of Arion ater. Five specimens of the same species were once noticed busily devouring a May-fly each, and this in the middle of a large meadow, where it may be presumed there was no lack 1 Zoologist, ii. p. 296; iii. p. 833; iv. p. 1216; iii. p. 1036; iv. p. 1216; iii p. 1037. 2 Ann. Nat. Hist. ii. 1838, p. 310. * H. W. Kew, Naturalist, 1889, p. 103. 4 Zeit. wiss. Zool. xlii. p. 208 f. 5 Sci. Trans. R. Dubl. Soc. (2) iv. p. 520. 32 FOOD OF SLUGS CHAP. of green food.’ The capture and eating of insects by Mollusca seems very remarkable, but this story does not stand alone. Mr. T. Vernon Wollaston once enclosed in a bottle at least three dozen specimens of Coleoptera together with 4 Helix cantiana, 5 H. hispida, and 1 H. virgata, together with an abundant sup- ply of fresh leaves and grass. About a fortnight afterwards, on the bottle being opened, it was found that every single speci- men of the Coleoptera had been devoured by the snails. Amalia marginata in captivity has been fed upon the larvae of Huchelia jacobaeae, eating three in two hours.” Limax maximus (Fig. 19) has been seen frequently to make its way into a dairy and feed on raw beef.? Individuals kept in : confinement are guilty of cannibalism. Mr. W. A. .Gain kept three specimens -~~ in a box together, and found one of them two-thirds eaten, “the tail left clean cut off, reminding one of that por- tion of a fish on a fishmon- eT ater ger’s stall.” That starvation ee did not prompt the crime Fic. 19.—Limax maximus L. PO, pulmo- was proved by the fact that naryonices Ae during the preceding night the slug had been supplied with, and had eaten, a consid- erable quantity of its favourite food. On two other occasions the same observer found one of his slugs deprived of its slime and a portion of its skin, and ina dying condition. a An adult | LL. maximus, kept for thirty-three days in captivity with a young Arion ater, attacked it frequently, denuded it of its slime, and gnawed numerous small pieces of skin off the body and mantle.° The present writer has found no better bait for this species on a warm summer night than the bodies of its brethren which were slain on the night preceding; it will also devour dead Helix aspersa. Mr. Gain considers it a very dainty feeder, preferring fungi to all other foods, and apparently doing no harm in the garden. 1 Zoologist, iv. p. 1504; iii. p. 1088; iii. p. 948. 2H. W. Kew, J. c. 8 Zoologist, xix. p. 7819. 4 Naturalist, 1889, p. 55. 5H. W. Kew, i. c. i FOOD OF SLUGS AND SNAILS) 33 Limax flavus, which is fond of inhabiting the vicinity of cellars, makes its presence most disagreeable by attacking articles of food, and especially by insinuating itself into vessels contain- ing meal and flour.! It is particularly partial to cream. Oe i 8 Slugs will sometimes bite their captor’s hands. Mr. Kew’ | relates that a Limax agrestis, on being stopped with the finger, while endeavouring to escape from the attack of a large Arion, attempted to bite fiercely, the rasping action of its radula being plainly felt. According to the same authority, probably all the slugs will rasp the skin of the finger, if it is held out to them, and continue to do so for a considerable time, without however actually drawing blood.2, While Mr. Gain was handling a large Arion ater, it at once seized one of the folds of skin between the fingers of the hand on which it was placed; after the action of the radula had been allowed to continue for about a minute, the skin was seen to be abraded.? Another specimen of Arion ater, carried in the hand fora long time enclosed in a dock leaf, began to rasp the skin. The operation was permitted until it became too painful to bear. Examination with a lens showed the skin almost rasped away, and the place remained tender and sore, like a slight burn, for several days.* Helix pisana, if freshly caught, and placed in a box with other species, will set to work and devour them within twenty- four hours. The present writer has noticed it, in this position, attack and kill large specimens of H. ericetorum, cleaning them completely out, and inserting its elongated body into the top whorls of its unfortunate victims in a most remarkable manner. Amongst a large number of species bred in captivity by Miss F. M. Hele,® was Hyalinia Draparnaldi. In the first summer the young offspring were fed on cabbage, coltsfoot, and broad- leafed docks. They would not hibernate even in the severest frosts, and, no outdoor food being available, were fed on chopped beef. This, Miss Hele thinks, must have degenerated their appetites, for in the following spring and summer they con- stantly devoured each other. Zonites algirus feeds on decayed fruit and vegetables, and on stinking flesh.© Achatina panthera has been known to eat _1W.G. Binney, Bull. Mus. C. Z. Harv. iv. p. 144. 2 Naturalist, 1. c. | ~ 8 Science Gossip, 1885, p. 154. 4*R. Standen, Journ. of Conch. vii. p. 197. ~ 5 Journ. of Conch. v. p. 43. 6 A. Paladilhe in MS. letter. VOL. III D 34 FOOD OF SLUGS AND SNAILS CHAP. meat, other snails (when dead), vegetables, and paper.1 The common Stenogyra decollata of the South of Europe has a very bad character for flesh-eating habits, when kept in captivity. Mr. Binney? kept a number for a long time as scavengers, to clean the shells of other snails. As soon asa living Heliz was placed in a box with them, one would attack it, introduce itself into the upper whorls, and completely remove the animal. One day a number of Succinea ovalis were left with them for a short time, and disappeared entirely! The Stenogyra had eaten shell as well as animal. This view of Stenogyra is quite confirmed by Miss Hele, who has bred them in thousands. “I can keep,” she writes,’ “no small Heliw or Bulimus with them, for they at once kill and eat them. ‘They will also eat raw meat.” Even the common Limnaea stagnalis, which is usually re- garded as strictly herbivorous, will sometimes betake itself, apparently by preference, to a diet of flesh. Karl Semper fre- quently observed the Limnaeae in his aquarium suddenly attack healthy living specimens of the common large water newt (Z7r- ton taeniatus), overcome them, and devour them, although there was plenty of their favourite vegetable food growing within easy reach. The same species has also been noticed to devour its own ova, and the larvae of Dytiscus. Limnaea peregra has been detected capturing and partially devouring minnows in an aqua- rium, when deprived of other food, and Dr. Jeffreys has seen the same species attack its own relatives under similar circum- stances, piercing the spire at its thinnest point near to the apex.® L. stagnalis, kept in an aquarium, has succeeded in overpower- ing and partially devouring healthy specimens of the common stickleback.® Powers of Intelligence, Homing, and finding Food. — It is not easy to discover whether land Mollusca possess any faculties which correspond to what we call intelligence, as distinct from their capacities for smell, sight, taste, and hearing. Darwin mentions’ a remarkable case, communicated to him by Mr. Lonsdale. A couple of Helix pomatia, one of which was sickly, 1J.8. Gibbons, Quart. Journ. Conch. ii. p. 148. 2 Bull. Mus. C. Z. Harv. iv. p. 198. 31. c. p. 362. 4 Animal Life, p. 59. 5 Zoologist, 1861, p. 7400; Brit. Conch. i. p. 108. 6 H. Ullyett, Science Gossip, xxii. (1886), p. 214. 7 Descent of Man, i. p. 825, ed. 1. Il HOMING AND FINDING FOOD 35 were placed in a small and ill-provided garden. The stronger of the two soon disappeared over the wall into the next garden, which was well furnished with food. It was concluded that the snail had deserted its weakly mate, but after twenty-four hours it returned, and apparently communicated the results of its ex- pedition, for after a short time both started off along the same track, and disappeared over the wall. According to Dr. W. H. Dall,! a young girl who possessed a remarkable power over ani- mals succeeded in training a snail (#. albolabris) to come out of its lurking-place at her call. If placed in a room, it would shrink into its shell at the sound of any other voice, but it would always start off in the direction of hers. Snails and slugs possess to a considerable extent the faculty of ‘homing,’ or returning to the same hiding-place day after day, after their night excursions in search of food. Mr. C. Ash- ford once marked with a dab of white paint seven Helix aspersa found lurking under a broken flagstone; at 10 p.m. the same evening three had disappeared on the forage; the next morning all were ‘at home.’ The following night at 10 P.M. five were gone out, two being discovered with some difficulty ‘in a small jungle’ six feet away; the next morning six out of the seven were safely beneath the flagstone. According to the same authority, Helix aspersa will find its way across a cinder-path (which it specially detests) to get to its favourite food, and will return by the same way to its old quarters, although it could easily have found new lodgings nearer the food-supply. A snail has been observed to occupy a hole in the brick wall of a kitchen-garden about four feet from the ground. Leaning against the wall, and immediately under the hole, was a piece of wood, the lower end of which rested in a bed of herbs. For months the snail employed this ladder between its food and its home, coming down as soon as it was dark, and retiring to rest during the day. In greenhouses a slug will forage night after night — as gar- deners know to their cost — over the same beat, and will always return to the same hiding-place. Lzmaz flavus has been noticed crawling with great regularity to a sink from a hole near the water-pipe, and keeping to a well-marked circular track. In all probability the scent, either of the desired object of food, or of 1 Amer. Nat. xv. 1881, p. 976. 36 . HOMING AND FINDING FOOD CHAP. the creature’s own trail, plays a considerable part in keeping it to the same outward and homeward track, or at least in guiding it back to its hiding-place. Yet even scent is occasionally at fault, for on one occasion a Limaz flavus was accustomed to make nightly excursions to some basins of cream, which were kept in a cool cellar. When the basins were removed to a distant shelf, the ‘creature was found the next morning ‘ wandering disconso- lately ’ about in the place where the basins had formerly stood.} A remarkable case of the power of smell, combined with great perseverance on the part of a Helix, is recorded by Furtado.” He noticed a Helix aspersa lodged between a column on a verandah and a flower-pot containing a young banana plant, and threw it away into a little court below, and six or seven yards distant. Next morning the snail was in precisely the same place on the flower-pot. Again he threw it away, to the same dis- tance, and determined to notice what happened. Next morning at nine o’clock, the snail was resting on the rail of a staircase leading up to the verandah from the court; in the evening it started again, quickening its space as it advanced, eventually attacking the banana in precisely the same place where it had been gnawed before. For further instances of the power of smell in snails, see chap. vil. Slugs have been known to make their way into bee-hives, presumably, for the sake of the honey.2 ‘Sugaring’ the trees at night for moths will often attract a surprising concourse of slugs. Sometimes a particular plant in a greenhouse will become the object of the slugs’ persistent attacks, and they will neglect every other food in order to obtain it. Farfugiwm grande is one of © these favourite foods, “the young leaves and shoots being always eaten in preference to all other plants growing in the houses; where no Farfugiwms were kept the slugs nibbled indiscrimi- nately at many kinds.”* The flowers of orchidaceous plants _ exercise a special attraction over slugs, which appear to have some means of discovering when the plants are in bloom. “I~ have often observed,” says Mr. T. Baines, “that a slug will travel over the surface of a pot in which is growing a Dendrobium 1W. A. Gain, quoted by H. W. Kew in Naturalist, 1890, p. 307, an article to which I am much indebted. 2 Ann. Mag. Nat. Hist. (6) xvi. p. 619. 3 Science Gossip, 1882, pp. 287, 262. 4H. W. Kew, Naturalist, 1893, p. 149, another most valuable article. 11 SLUGS IN GREENHOUSES 37 nobile, a Cattleya, Vanda, or similar upright plant for a score of times without ever attempting to ascend into the head of the plant unless it is in bloom, in which case they are certain to find their way straight to the flowers; after which they will descend, and return to some favourite hiding-place, often at the opposite end of the house.”! Mr. R. Warner has “actually seen many little slugs suspending themselves by slime-threads from the rafters and descending on the spikes of the beautiful Odonto- glossum alexandrae; and thus many spikes, thickly wadded round with cotton wool (which the slugs could not travel over), and growing in pots surrounded by water, had been lost.”2 Perhaps the most singular instance of a liking for a particular food is that related by Mr. E. Step.2 In a London publishing house, slugs were observed, during a period of nearly twelve months, to have fed almost nightly on the colouring matter in certain bookcovers, and though the trails were often seen over the shelves, and cabbage and lettuce leaves laid down to tempt the creatures, they continued their depredations with impunity for the time above mentioned. Limnaea peregra has been observed feeding on old fish-heads thrown into a dirty stream, and a large gathering of Limnaea stagnalis has been noticed feeding upon an old newspaper in a pond on Chislehurst Common, ‘so that for the space of about a square foot nothing else could be seen.’ # at Tenacity of Life.— Land Mollusca have been known to exhibit, under unusual conditions, remarkable tenacity of life. Some of the most noteworthy and best authenticated instances of this faculty may be here mentioned. The well-known story of the British Museum snail is thus related by Mr. Baird.® On the 25th March 1846 two specimens of Helix desertorum, collected by Charles Lamb, Esq., in Egypt some time previously, were fixed upon tablets and placed in the collection among the other Mollusca of the Museum. There they remained fast gummed to the tablet. About the 15th March 1850, having occasion to examine some shells in the same case, Mr. Baird noticed a recently formed epiphragm over the mouth of one of these snails. On removing the snails from the tablet 1 Garden, v. p. 201, quoted by Kew, wt sup. 2 Kew, wt sup. 8 Science Gossip, 1888, p. 163. 4T. D. A. Cockerell, Science Gossip, 1885, p. 211. 5 Ann. Mag. Nat. Hist. (2) vi. (1850) p. 68. 38 TENACITY OF LIFE CHAP. and placing them in tepid water, one of them came out of its shell, and the next day ate some cabbage leaf. A month or two afterwards it began repairing the lip of its shell, which was broken when it was first affixed to the tablet. While resident in Porto Santo, from 27th April to 4th May 1848, Mr. S. P. Woodward! collected a number of Helices and sorted them out into separate pill-boxes. On returning home, these boxes were placed in empty drawers in an insect cabinet, and on 19th October 1850, nearly two and a half years after- wards, many of them were found to be still alive. A whole bagful of H. turricula, collected on the Ilheo de Cima on 24th April 1849, were all alive at the above-mentioned date. In September 1858 Mr. Bryce Wright sent? to the British Museum two specimens of H. desertorum which had been dor- mant for four years. They were originally collected in Egypt by a Mr. Vernédi, who, in May 1854, while stopping at one of the stations in the desert, found a heap of thorn-bushes lying in a corner of the building, rather thickly studded with the snails. He picked off fifteen or twenty specimens, which he carried home and locked up in a drawer, where they remained undis- turbed until he gave two to Mr. Wright in September 1858. In June 1855 Dr. Woodward placed specimens of A. candi- dissima and H. aperta in a glass box, to test their tenacity of life; he writes of their being still alive in April 1859. Mr. R. E. C. Stearns records? a case of Buliminus pallidior and H. Veatchit from Cerros I. living without food from 1859 to March 1865. H. Aucapitaine mentions‘ a case of H. lactea found in cal- cinated ground in a part of the Sahara heated to 122° F., where no rain was said to have fallen for five years. The specimen re- vived after being enclosed in a bottle for three and a half years. In August 1868, Mr. W. J. Sterland® put specimens of 4. nemoralis in a box and afterwards placed the box in his cabinet ; in November 1866 one specimen was discovered to be alive. Gaskoin relates ® a case in which specimens of H. lactea were purchased from a dealer in whose drawer they had been for two 1 Ann. Mag. Nat. Hist. (2) vi. p. 489. 2 Ibid. (8) iii. p. 448. 8 Amer. Nat. xi. (1877) p. 100; Proc. Calif. Ac. iii. p. 329. 4 Gaz. Med. Alger. 1865, 5th Jan. p. 9. 5 Science Gossip, 1867, p. 40. 6 Ann. Mag. Nat. Hist. (2) ix. p. 498. u AGE OF SNAILS 39 years. This dealer had them from a merchant at Mogador, who had kept them for more than that time under similar conditions. One of these shells on being immersed in water revived, and.in April 1849 was placed quite alone under a bell jar with earth and food. In the end of the following October about thirty young #H. lactea were found crawling on the glass. Mr. R. D. Darbishire bought! some H. aperta in the market at Nice on 18th February 1885. Two specimens of these, placed with wool in a paper box, were alive in December 1888. This is a very remarkable case, H. aperta not being, like H. deserto- rum, H. lactea, H. Veatechi and Bul. pallidior, a desert snail, and therefore not accustomed to fasting at all. Age of Snails.— It would appear, from the existing evi- dence, which is not too plentiful, that five years is about the average age of the common garden snail. Mr. Gain has pub- lished 2 some interesting observations on the life of a specimen from the cradle to the grave, which may be exhibited in a tabu- lar form. Aug. 1882. Eggs hatched ; one attained diameter of 2 in. before winter; fed on coltsfoot and cabbage. oth Oct. 1883. Shell 1 in. in diameter, no lip formed. July 1884. Shell finished; diameter 1} in., including _ perfect lip. 3rd May 1885. Left winter quarters; companion introduced, with which it was seen in company on 5th August. 9th Aug. “ Laid eggs in soil, which were hatched on 10th September, and feeding on 17th Sep- tember; in May 1886 the largest of these was 44 in. diameter. 13th Oct.1887. Old snail died, aged 5 years 2 months. According to Clessin, the duration of life in Vitrina is one year, Cyclas 2 years; Hyalinia, Succinea, Limnaea, Planorbis, and Ancylus are full grown in 2 to 8 years, Helix and Paludina in 2 to 4, and Anodonta in 12 to 14. Hazay finds? that the duration of life in Hyalinia is 2 years, in Helix pomatia 6 to 8, in Helix candicans 2 to 3, in Paludina 8 to 10, in Limnaea and Planorbis 3 to 4. 1 Journ. of Conch. vi. p. 101. 2 Naturalist, 1889, p. 55. 3 Malak. Blatt. (2) iv. pp. 43 and 221. 40 GROWTH OF THE SHELL CHAP. Growth of the Shell. — Mr. E. J. Lowe, many years ago, conducted! some interesting experiments on the growth of snails. The facts arrived at were — (1) The shells of Helicidae increase but little for a consider- able period, never arriving at maturity before the animal has once become dormant. (2) Shells do not grow whilst the animal itself remains dormant. (3) The growth of shells is very rapid when it does take place. (4) Most species bury themselves in the ground to increase the dimensions of their shells. Six recently hatched H. pomatia were placed in a box and regularly fed on lettuce and cabbage leaves from August until December, when they buried themselves in the soil for winter; at this period they had gradually increased in dimensions to the size of H. hispida. On the 1st April following, the box was placed in the garden, and on the 8rd the Helices reappeared on the surface, being no larger in size than they were in December. Although regularly fed up to 20th June, they were not per- ceptibly larger, but on that day five of them disappeared, having buried themselves, with the mouth of the shell downwards, in the soil. After ten days they reappeared, having in that short time grown so rapidly as to be equal in size to H. pisana. On the 15th July they again buried themselves, and reappeared on 1st August, having again increased in size. For three months from this date they did not become perceptibly larger; on 2nd November food was withheld for the winter and they became dormant. A similar experiment, with similar results, was carried on with a number of H. aspersa, hatched on 20th June. During the summer they grew but little, buried themselves on 10th October with the head upwards, and rose to the surface again on oth April, not having grown during the winter. In May they buried themselves with the head downwards, and appeared again in a week double the size; this went on at about fort- nightly intervals until 18th July, when they were almost fully grown. Helix nemoralis, H. virgata, H. caperata, and H. hispida bury 1 Phil. Trans. 1854 (1856), p. 8. II SELF-BURIAL OF SNAILS 4I themselves to grow; H. rotundata burrows into decayed wood ; Hyalinia radiatula appears to remain on decaying blades of grass ; Pupa umbilicata, Clausilia rugosa, and Buliminus obscurus bury their heads only. | The observations of Mr. W. E. Collinge! do not at all agree with those of Mr. Lowe, with regard to the mode in which land Mollusca enlarge their shells. He bred and reared most of the commoner forms of Helix and also Clausilia rugosa, but never saw them bury any part of their shell when enlarging it. While admitting that they may increase their shells when in holes or burrows of earthworms, he thinks that the process of burying would seriously interfere with the action of the mantle during deposition, and in many cases damage the membranaceous film before the calcareous portion was deposited. Mr. Collinge has found the following species under the surface in winter: Arion ater (8-4 in.), Agriolimax agrestis (6-8 in.), Hyalinia cellaria and H. alliaria (6-8 in.), Hyalinia glabra (5 in.), Helix aspersa (5-6 in.), H. rufescens (4-6 in.), H. rotundata (4-5 in.), Hi. hispida (7 in.), Buliminus obscurus (4-6 in.), B. montanus? (24 in.), and the following in summer, Hyalinia cellaria and alliaria (6-8 in.), Helix rotundata (4-5 in.), Balea perversa (6-8 in.), Cyclostoma elegans (8-4 in.). The same author has found the following species of fresh-water Mollusca living in hard dry mud: Sphaerium corneum (8-14 in.), S. rivicola (5-6 in.), S. lacustre (10-14 in.), all the British species of Pzsidium (4-12 in.), Limnaea truncatula (18 in., a single specimen). All our species of Unio, Anodonta, Bithynia, and Paludina bury themselves habitually in fine or thick wet mud, to a depth of from 4 to 14 inches. This burying propensity on the part of Mollusca has been known to play its part in detecting fraud. When my friend Mr. E. L. Layard was administering justice in Ceylon, a native landowner on a small scale complained to him of the conduct of his neighbour, who had, during his absence from home, diverted a small watercourse, which ran between their holdings, in such a way as to filch a certain portion of the land. The offender had filled up and obliterated the ancient course of the stream, and protested that it had never run but in its present bed. 1 Naturalist, 1891, p. 75 f.; Conchologist, ii. 1892, p. 29. 2 Taylor, Journ. of Conch. 1888, p. 299. 42 DEPOSITION OF EGGS CHAP. | Mr. Layard promptly had a trench sunk across what was said to — be the old course, and the discovery of numerous living Ampul- laria, buried in the mud, confirmed the story of one of the litigants and confounded the other.! Depositing and Hatching of Eggs: Self-fertilisation. — There appears to be no doubt that Helices, when once impreg- nated, can lay successive batches of eggs, and possibly can con- tinue laying for several years, without a further act of union. A specimen of Helix aspersa was noticed in company with another on 5th August; on 9th August it laid eggs in the soil, and early in the following summer it laid a second batch of eggs, although its companion had been removed directly after its first introduction. . An Arion received from a distance laid 30 eggs on oth September, and 70 more on the 23rd of the same month, although quite isolated during the whole time.2 By far the most remarkable case of the kind is related by Gaskoin2 A specimen of Helix lactea was kept in a drawer for about two years, and then in another drawer for about two years more. It was then taken out, and placed in water, when it revived, and was placed alone under a bell jar with earth and food. Six months after, about 380 young WH. lactea were found crawling on the glass, the act of oviposition not having been observed. The observations of Mr. F. W. Wotton,* with regard to the fertilisation and egg-laying of Arion ater, are of extreme inter- est and value. A pair of this species, kept in captivity, united on 10th September 1889, the act lasting about 25 minutes. From that date until the eggs were laid, the animals looked sickly, dull of colour, with a somewhat dry skin. Eggs were deposited in batches, one, which we will call A, beginning three days before B. On 10th October A laid 80 eggs; on the 16th, 110; on the 25th, T7; on 8th November, 82; and on 17th November, 47; making a total of 396. Specimen B, which began on 13th October, three days after A, made up for the delay by laying 246 eggs in 40 hours; on 26th October it laid 9, on 10th November, 121; and on 80th November, 101; a total of 1 See Tennent’s Ceylon, i. p. 221, ed. 5. 2W. A. Gain, Natwralist, 1889, p.55; Brockmeier, Nachr. Deutsch. Malak. Gesell. xx. p. 118. 3 Ann. Mag. Nat. Hist. (2) ix. p. 498. 4 Journ. Conch. vii. 1893, p. 158 f. it HATCHING OF EGGS 43 A477. These eggs weighed 624 to the ounce, and, in excluding the batch of 246, B parted with 2 of its own weight in 40 hours, while the whole number laid were rather over $ of its own weight ! While depositing the eggs, the slug remained throughout in the same position on the surface of the ground, with the head drawn up underneath the mantle, which was lifted just above the reproductive orifice. When taken into the hand, it went on laying eggs without interruption or agitation of any kind. After it had finished laying it ate half a raw potato and then took a bath, remaining submerged for more than an hour. Bathing is a favourite pastime at all periods. Specimens, says Mr. Wotton, have survived a compulsory bath, with total submersion, of nearly three days’ duration. Mr. Wotton’s account of the hatching of the eggs is equally interesting. It is noticeable that the eggs of one batch do not hatch by any means simultaneously; several days frequently intervene. The average period is about 60 days, a damp and warm situation bringing out the young in 40 days, while cold and dryness extended the time to 74 days, extremes of any kind proving fatal. Of the batch of eggs laid by Bon 380th Novem- ber, the first 2 were hatched on the following 16th January, and 2 more on the 17th; others, from 10 to 20, followed suit on the succeeding 5 days, until 82 in all were hatched, the remaining 19 being unproductive.! By placing the egg on a looking-glass the act of exclusion ean be perfectly observed. For several days the inmate can be seen in motion, until at last a small crack appears in the surface of the shell: this gradually enlarges, until the baby slug is able - to crawl out, although it not unfrequently backs into the shell again, as if unwilling to risk itself in the world. When it once _ begins to crawl freely, it buries itself in the ground for 4 or 5 days without food, after which time it emerges, nearly double its original size. At exclusion, the average length is 9 mm., increasing to 56 mm. after the end of 5 months. Full growth is attained about the middle of the second year, and nearly all ‘ die at the end of this year or the beginning of the next. Death from exhaustion frequently occurs after parturition. Death r) 4 i 1 Tsucceeded in hatching out eggs of Helix aspersa, during the very warm _ Summer of 1893, in 17 days. A4 REPRODUCTION OF LOST PARTS CHAP. from suffocation is sometimes the result of the formation of small blisters on the margin of the respiratory aperture. The attacks of an internal parasite cause death in a singular way. The upper tentacles swell at the base in such a way as to pre- vent their extrusion; digestive troubles follow, with rigidity and loss of moisture, and death ensues in 2 or 3 days. Mr. Wotton isolated newly-hatched specimens, with the view of experimenting on their power of self-fertilisation, if the op- portunity of fertilising and being fertilised by others was denied them. One of these, after remaining in absolute solitude for 104 months, began to lay, scantily at first (11th January, 2; 25th January, 2; 11th February, 2), but more abundantly afterwards (8rd April, 60; 15th and 16th, 70; 29th, 538, etc.), the eggs be- ing hatched out in 42-48 days. The precautions taken seem to have been absolutely satisfactory, and the fact of the power of self-fertilisation appears established as far as Arion ater is con- cerned. Braun took young individuals of Limnaea auricularia on the day they were hatched out, and placed them singly in separate vessels with differing amounts of water. ‘This was on 1dth June 1887. In August 1888 specimen A had only produced a little spawn, out of which three young were hatched; specimen B had produced four pieces of spawn of different sizes, all of which were hatched; specimen C, which happened to be living with three Planorbis, produced five pieces of spawn distinctly Limnaeidan, but nothing is recorded of their hatching. Self- impregnation, therefore, with a fruitful result, appears estab- lished for this species of Limnaea.} Reproduction of Lost Parts. — When deprived of their ten- tacles, eyes, or portions of the foot, Mollusca do not seem to suffer severely, and generally reproduce the lost parts in a short time. If, however, one of the ganglia is injured, they perish. Certain of the Mollusca possess the curious property of being — able to amputate certain parts at will. When Prophysaon, a species of Californian slug, is annoyed by being handled, an in- dented line appears at a point about two-thirds of the length from the head, the line deepens, and eventually the tail is shaken completely off. Sometimes the Prophysaon only threatens this spontaneous dismemberment; this line appears (always exactly 1 Nachr. Deutsch. Malak. Gesell. xx. p. 146. II STRENGTH OF SNAILS 45 in the same place), but it thinks better of it, and the indentation proceeds no further.!. According to Gundlach,? Helix imperator and H. crenilabris, two large species from Cuba, possess the same property, which is said to be also characteristic of the sub- genus Stenopus (W. Indies). Amongst marine species, Harpa ventricosa and Solen siliqua have been observed to act in a simi- lar way, Harpa apparently cutting off the end of the foot by pressure of the shell. Karl Semper, in commenting on the same property in species of Helicarion from the Philippines (which whisk their tail up and down with almost convulsive rapidity, until it drops off), considers? it greatly to the advan- tage of the mollusc, since any predacious bird which attempted to seize it, but only secured a fragment of tail, would probably be discouraged from a second attack, especially as the Helicarion would meanwhile have had time to conceal itself among the foliage. Strength and Muscular Force.— The muscular strength of snails is surprisingly great. Sandford relates * an experiment on a Helix aspersa, weighing + oz. He found it could drag verti- eally a weight of 2} oz., or nine times its own weight. Another snail, weighing 4 oz., was able to drag in a horizontal direction along a smooth table twelve reels of cotton, a pair of scissors, a screwdriver, a key, and a knife, weighing in all no less than 17 oz., or more than fifty times its own weight. This latter ex- periment was much the same as asking a man of 12 stone to pull a load of over 32 tons. If a snail be placed on a piece of glass and made to crawl, it will be seen that a series of waves appear to pursue one another along the under surface of the foot, travelling from back to front in the direction in which the animal is moving. Simroth has shown that the sole of the foot is covered with a dense net- work of muscular fibres, those which run longitudinally being chiefly instrumental in producing the undulatory motion. By means of these muscles the sole is first elongated in front, and then shortened behind to an equal extent. Thus a snail slides, not on the ground, but on its own mucus, which it deposits mechanically, and which serves the purpose of lubricating the 1 Raymond, Nautilus, iv. p. 6. 2 Quoted by Oehlert, Rév. Sc. xxxviii. p. 701. 3 Animal Life, Intern. Scientif. Ser. ed. 1, p. 395. + Zoologist, 1886, p. 491. 46 SUDDEN APPEARANCE AND DISAPPEARANCE CHAP. ground on which it travels. It has been calculated that an averaged sized snail of moderate pace progresses at the rate of about a mile in 16 days 14 hours.! Sudden Appearance of Mollusca.—It is very remarkable to notice how suddenly Pulmonata seem to appear in certain districts where they have not been noticed before. This sudden appearance is more common in the case of fresh-water than of land Mollusca, and there can be little doubt that, wherever a new pond happens to be formed, unless there is something in its situation or nature which is absolutely hostile to molluscan life, Mollusca are certain to be found in it sooner or later. ‘Some 23 years ago,” writes Mr. W. Nelson,? “I was in the habit of collecting shells in a small pond near to the Black Hills, Leeds. At that time the only niolluscan forms found there were a dwarf form of Sphaerium lacustre, Pisidium pusillum, Planorbis nau- tileus, and Limnaea peregra. About 10 years ago I resumed my visits to the locality, and found, in addition to the species already enumerated, Planorbis corneus. ‘These were the only species found there until this spring [1883], when, during one of my frequent visits, I was surprised to find Physa fontinalis and Planorbis vortex were added to the growing list of species. Later on Pl. carinatus, Limnaea stagnalis, and Ancylus lacustris tarned up; and during June, Pl. contortus was found in this small but prolific pond.” Limnaea glutinosa is prominent for these re- markable appearances and disappearances. In 1822 this species suddenly appeared in some small gravel pits at Bottisham, Cambs., in such numbers that they might have been scooped out by handfuls. After that year they did not appear numer- ous, and after three or four seasons they gradually disappeared.? Physa (Aplecta) hypnorum is noted in a similar way. In Feb- ruary 1852, for instance, after a wet month, the water stood in small puddles about 8 feet by 2 in a particular part of Bottisham Park which was sometimes a little swampy, though usually quite dry. One of these puddles was found to contain immense num- — bers of the Aplecta, which up to that time had not been noted as occurring in Cambridgeshire at all. Ina few days the species entirely disappeared and was never again noticed in the locality.® 1 Thomas, quoted by Jeffreys, Brit. Conch.i.p.30. 2 Journ. of Conch. iv. p. 117. ° Rev. L. Jenyns, Observations in Nat. Hist. p. 318. 4 Id. ib. p. 319. 5 Further detailed examples will be found in Kew, The dispersal of Shells, pp. 5-26. n SHOWERS OF SHELLS 47 Writing to the Zoological Society of London from New Caledonia, Mr. E. L. Layard remarks:! “The West Indian species Stenogyra octona has suddenly turned up here in thou- sands; how introduced, none can tell. They are on a coffee estate at Kanala on the east coast. I have made inquiries, and cannot find that the planter ever had seed eoffee from the West Indies. All he planted came from Bombay, and it. would be interesting to find out whether the species has appeared there also.” 2 Sometimes a very small event is sufficient to disturb the natural equilibrium of a locality, and to become the cause either of the introduction or of the destruction of a species. In 1883 a colony of Helix sericea occupied a portion of a hedge bottom twenty yards long near Newark. It scarcely occurred outside this limit, but within it was very plentiful, living in company with . nemoralis, H. hortensis, H. hispida, H. rotundata, Hyalinia cellaria and Hy. nitidula, and Cochlicopa lubrica. In 1888 the hedge was well trimmed, but the bottom was not touched, and the next year a long and careful search was required to find even six specimens of the sericea? Showers of Shells. — Helix virgata, H. caperata, and Cochli- cella acuta sometimes occur on downs near our sea-coasts in such extraordinary profusion, that their sudden appearance out of their hiding-places at the roots of the herbage after a shower of rain has led to the belief, amongst credulous people, that they have actually descended with the rain. There seems, however, no reason to doubt that Mollusca may be caught up by whirl- winds into the air and subsequently deposited at some consid- erable distance from their original habitat, in the same way as frogs and fishes. A very recent instance of such a phenomenon occurred? at Paderborn, in Westphalia, where, on 9th August 1892, a yellowish cloud suddenly attracted attention from its colour and the rapidity of its motion. In a few moments it burst, with thunder and a torrential rain, and immediately after- wards the pavements were found to be covered with numbers of Anodonta anatina, all of which had the shell broken by the violence of the fall. It was clearly established that the shells 1P. Z. §. 1888, p. 358. 2W. A. Gain, Naturalist, 1889, p. 58. 8 Das Wetter, Dec. 1892. Another case is recorded in Amer. Nat. iii. p. 556. 48 SINGULAR HABITAT—UNDERGROUND SNAILS CHAP. could not have been washed into the streets from any adjacent river or pond, and their true origin was probably indicated when it was found that the funnel-shaped cloud which burst over the town had passed across the one piece of water near Paderborn, which was known to contain the Anodonta in abundance. | | Cases of Singular Habitat. — Mollusca sometimes accus- tom themselves to living in very strange localities, besides the extremes of heat and cold mentioned above (pp. 238-24). In the year 1852, when some large waterpipes in the City Road, near St. Luke’s Hospital, were being taken up for repairs, they were found to be inhabited in considerable numbers by Weritina fluviatilis and a species of Limnaea.| Dreissensia polymorpha has been found in a similar situation in Oxford Street, and also in Hamburg, and has even been known to block the pipes and cisterns of private houses. In an engine cistern at Burnley, 60 feet above the canal from which the water was pumped into the cistern, were found the following species: Sphaeriwm corneum, S. lacustre; Valvata piscinalis, Bithyna tentaculata ; Limnaea peregra, very like Suecinea in form and texture; Planorbis albus, P. corneus, P. nitidus, P. glaber, and thousands of P. dilatatus, much larger than the forms in the canal below, a fact probably due to the equable temperature of the water in the cistern all the year round.? In certain parts of southern Algeria the fresh-water genera Melania and Melanopsis inhabit abundantly waters so surcharged with salt that the marine Cardium edule has actually become extinct from excess of brine. The common Mytilus edulis is sometimes found within the branchial chamber and attached to the abdomen of crabs (Carcinus maenas), which are obliged to carry about a burden of which they are powerless to rid themselves (see p. 78). A variety of the common Limnaea peregra lives in the hot water of some of the geysers of Iceland, and has accordingly been named geisericola. Underground Snails. — Not only do many of the land Mol- lusca aestivate, or hibernate, as the case may be, beneath the surface of the soil, but a certain number of species live perma- nently underground, like the mole, and scarcely ever appear in the light of day. Our own little Caecilianella acicula lives 1 Zoologist, x. p. 8480. 2 Science Gossip, 1888, p. 281. Il UNDERGROUND AND ROCK-BORING SNAILS 49 habitually from 1 to 3 feet below ground, appearing to prefer the vicinity of graveyards. Testacella, the carnivorous slug, scarcely ever appears on the surface during the day, except when driven by excessive rain, and even then it lurks awhile under some protecting cover of leafage. There is a curious little Helix (tristis Pir.), peculiar to Corsica, which is of dis- tinctly subterranean habits. It lives in drifted sand above high- water mark, always at the roots of Genista Saltzmanni, at a depth which varies with the temperature and dryness of the air. In hot and very dry weather it buries itself nearly 2 feet below the surface, only coming up during rain, and burying itself again immediately the rain is over. Like a Solen, it often has a hole above its burrow, by which it communicates with the air above, so as to avoid being stifled in the sand. The animal, in spite of its dry habitat, is singularly soft and succulent, and exudes a very glutinous mucus. It probably descends in its burrow until it arrives at the humid stratum, the persistence of which is due to the capillarity of the sand. I am assured by Mr. E. L. Layard that precisely similar underground habits are characteristic of Coeliaxis Layardi, which lives exclusively in sand at the roots of scrub and coarse grass at East London. Rock-boring Snails. — Cases have sometimes been recorded, from which it would appear that certain species of snails possess the power of excavating holes in rocks to serve as hiding-places. At Les Bois des Roches, ten miles from Boulogne, occur a number of solid calcareous rocks scattered about in the wood. The sides of the rocks which face N.E. and E. are covered with multitudes of funnel-shaped holes, 14 inch in diameter at the opening and contracting suddenly within to 4 inch. Sometimes the holes are 6 inches deep, and terminate, after considerable windings, in a cup-shaped cavity. Helix hortensis inhabits these holes, and has been observed to excavate them at the rate of 4 inch each hibernation, choosing always the side of the rock which is sheltered from the prevailing rains. It does not form an epiphragm, but protrudes part of its body against the rock. That the snails secrete an acid which acts as a solvent seems probable from the fact that red litmus paper, on being applied to the place where the foot has been, becomes stained with violet.? 1 Lecoq, Journ. de Conch. ii. p. 146. 2 Bouchard-Chantereaux, Ann. Sci. Nat. Zool. (4) xvi. (1861) p. 197. VOL. III E - 50 PRODUCTION OF MUSICAL SOUNDS CHAP. Helix aspersa is said to excavate holes 10 to 12 cm. deep at Constantine,! and H. Mazzulli is recorded as perforating lime- stone at Palermo.? Snails as Barometers. — An American writer of more than thirty years ago? gave his experience of Helices as weather- prophets. According to him, H. alternata is never seen abroad except shortly before rain; it then climbs on the bark of trees, and stations itself on leaves. Helix clausa, H. ligera, H. penn- sylvanica, and HH. elevata climb trees two days before rain, if it is to be abundant and continuous. Swecinea does the same, and its body is yellow before rain and bluish afterit. Several of the Helices assume a sombre colour after rain, when their bodies are exceedingly humid; after the humidity has passed off they resume a clearer and lighter tint. Production of Musical and other Sounds.— Certain mol- luses are said to be capable of producing musical sounds. Sir J. E. Tennent describes his visit to a brackish-water lake at Bat- ticaloa, in Ceylon, where the fishermen give the name of the ‘crying shell’ to the animal supposed to produce the sounds. “The sounds,” he says,* ‘came up from the water like the gen- tle thrills of a musical chord, or the faint vibrations of a wine- glass when its rim is rubbed by a moistened finger. It was not one sustained note, but a multitude of tiny sounds, each clear and distinct in itself; the sweetest treble mingling with the lowest bass. On applying the ear to the woodwork of the boat, the vibration was greatly increased in volume. The sounds varied considerably at different points as we moved across the lake, and occasionally we rowed out of hearing of them alto- gether.” According to the fishermen, the shells were Pyrazus palustris and Littorina laevis. It appears uncertain whether the sounds are really due to Mollusca. Fishermen in other parts of India assert that the sounds are made by fish, and, like those in Ceylon, produce the fish which they say ‘sings.’ The same, ora similar sound, has also been noticed to issue from the water in certain parts of Chili, and on the northern shores of the Gulf of 1 Forel, Ann. Sci. Nat. Wh xx. p. 576; Bretonniére, Comptes Rendus, cvii. i ae Mus. Collection. 3 Thomas, quoted by Récluz in Journ. de Conch. vii. 1858, p. 178. + Nat. Hist. of Ceylon, p. 882. See also T. L. Taylor, Rep. Brit. Ass. for 1848, p. 82, II HABITS OF CARNIVOROUS SNAILS AND SLUGS 51 Mexico. Dendronotus arborescens, when confined in a glass jar of sea water, has been noticed! to emit a sound like the clink of a steel wire. According to Lieut.-Col. Portlock,? F.R.S., Helix aperta, a very common species in South Europe, has the property of emitting sounds when irritated. When at Corfu, he noticed that if the animal is irritated by a touch with a piece of straw or other light material, it emits a noise, as if grumbling at being disturbed. He kept a specimen in his house for a con- siderable time, which would make this noise whenever it was touched. The Rev. H. G. Barnacle describes the musical properties of Achatinella in the following terms:? ‘* When up the mountains of Oahu I heard the grandest but wildest music, as from hun- dreds of Aeolian harps, wafted to me on the breezes, and my companion (a native) told me it came from, as he called them, the singing shells. It was sublime. I could not believe it, but a tree close at hand proved it. On it were many of the Acha- tinella, the animals drawing after them their shells, which grated against the wood and so caused a sound; the multitude of sounds produced the fanciful music. On this one tree I took 70 shells of all varieties.” Habits of the Agnatha. — Not much is known of the habits and mode of life of the Agnatha, or carnivorous Land Mollusca. In this country we have only two, or at most three, of this group, belonging to the genus Testacella, and, in all probability, not indigenous to our shores. There seems little doubt, when all the circumstances of their discovery are taken into account, that both TYestacella haliotidea and T. Maugei have been im- ported, perhaps from Spain or Portugal in the first instance, along with roots imbedded in foreign earth, for their earliest appearances can almost invariably be traced back to the neigh- bourhood of large nursery grounds, or else to gardens supplied directly from such establishments. The underground life of Testacella makes observation of its habits difficult. It is believed to feed exclusively on earth- worms, which it pursues in their burrows. Continued wet weather drives it to the surface, for though loving damp soil it 1 Dr. R. E. Grant, Edinb. Phil. Journ. xiv. p. 188. _2 Rep. Brit. Ass. for 1848, p. 80. The statement is confirmed by Rossmissler. @ Journ. of Conch. iv. p. 118. 52 HABITS OF CARNIVOROUS SNAILS AND SLUGS CHAP. is decidedly averse to too much moisture, and under such cir- cumstances it has even been noticed! in considerable numbers crawling over a low wall. In the spring and autumn months, according to Lacaze-Duthiers,? it comes to the surface at night, hiding itself under stones and débris during the day. LEarth- worms are, at, these periods, nearer the surface, and the Testacella has been seen creeping down into their burrows. The author has taken 7. Mauger abundantly under clumps of the common white pink in very wet weather, lying in a sort of open nest in the moist earth. On the other hand, when the earth is baked dry by continued drought, they either bury themselves deeper, sometimes at a depth of 3 feet, in the ground, or else become encysted in a capsule of hardened mucus to prevent evaporation from the skin. When first taken from the earth and placed in a box, the Testacella invariably resents its capture by spitting up the contents of its stomach in the shape of long fragments of half-digested worms. It appears not to bite the worm up before swallowing it, but contrives, in the most remarkable manner, to take down whole Fia. 20.— Testacella haliotidea Drap., protruding its pharynx (ph) and radula (7) ; oe, oesophagus; p.o, pulmonary orifice; sh, shell; ¢, tentacles (after Lacaze- Duthiers). worms apparently much too large for its stomach. Mr. Butterell relates? that, after teasing a specimen of 7. Maugez, and making it emit a quantity of frothy mucus from the respiratory aperture, he procured a worm of about three inches long, and rubbed the worm gently across the head of the Zestacella. The tongue was rapidly extended, and the victim seized. The odontophore was then withdrawn, carrying with it the struggling worm, which made every effort to escape, but in vain; in about five minutes all had disappeared except the head, which was rejected. This protrusion of the tongue (radula) and indeed of the whole 1 Zoologist, 1887, p. 29. 2 Arch. Zool. Exp. Gén. (2) v. p. 459 f. 3 Journ. of Conch. iii. p. 277 ; compare W. M. Webb, Zoologist, 1893, p. 281. II HABITS OF CARNIVOROUS SNAILS AND SLUGS 53 pharynx, is a very remarkable feature in the habits of the ani- mal. It appears, as it were, to harpoon its prey by a rapid thrust, and when the victim is once pierced by a few of the powerful sickle-shaped teeth (compare chap. viii.) it is slowly but surely drawn into the oesophagus (Fig. 20). Most gardeners are entirely ignorant of the character of Testacella, and contuse it, if they happen to notice it at-all, with the common enemies of their tender nurslings. Cases have been known, however, when an intelligent gardener has kept specimens on purpose to kill worms in ferneries or conservatories. In some districts these slugs are very numerous; Lacaze-Duthiers once dug 182 specimens from a good well-manured piece of ground whose surface measured only ten square yards. Towards the end of September or beginning of October the period of hibernation begins. I infer this from the behaviour of specimens kept in captivity, which, for about a fortnight before this time, gorged themselves inordinately on as many worms as I chose to put into their box, and then suddenly refused food, buried themselves deeply in the earth, and appeared no more during the winter. The eggs are apparently much less numerous than is the case with Limaz or Helix, and very large, measuring about 4 inch in diameter. They are enveloped in a remarkably tough and elastic membrane, and, if dropped upon any hard sur- face, rebound several inches, just like an india-rubber ball. The animal creeps rather rapidly, and has the power of elongating its body to a remarkable extent. When placed on the surface of the ground, in the full light of day, it soon betrays uneasiness, and endeavours to creep into concealment. Its method of burying itself is very interesting to watch. It first elongates its neck and inserts its head into the soil; gradually the body begins to follow, while the tail tilts upwards into the air. No surface motion of the skin, no writhing or wriggling motion of any kind occurs; the creature simply works its way down in a stealthy and mysterious way, until at last it is lost to view. The great Glandina, which attain their maximum develop- ment in Mexico and the southern United States, are a very noticeable family in this group. According to Mr. Binney,} Glandina truncata Gmel., one of the commonest species of the genus, is somewhat aquatic in its habits. It is found in the sea 1 Bull. Mus. Comp. Zool. Harv. iv. p. 85. 54 HABITS OF CARNIVOROUS SNAILS AND SLUGS CHAP. islands of Georgia and around the keys and everglades of Florida, where it attains a maximum length of 4 inches, while in less humid situations it scarcely measures more than 1 inch. It occurs most abundantly in the centre of clumps and tussocks of coarse grass in marshes close to the sea-coast. By the action of the sharp, sickle-shaped teeth of its radula the soft parts of its prey (which consists chiefly of living Helices) are rapidly rasped away ; sometimes they are swallowed whole. It has been known to attack Limax when confined in the same box, rasping off large pieces of the integument. In one case an individual was noticed to devour one of its own species, thrusting its long neck into the interior of the shell, and removing all the viscera. Fia. 21.— Glandina sowerbyana Pfr. (Strebel). The Glandinae of southern Europe, although scarcely rival- ling those of Central America in size or beauty, possess similar carnivorous propensities. Glandina Poireti has been observed,} on Veglia Island, attacking a living Cyclostoma elegans. By its powerful teeth it filed through two or three whorls of the shell of its victim, and then proceeded to devour it, exactly in the same manner as a Watica or Buccinum perforates the shell of a Tellina or Mactra in order to get at its contents. Few observations appear to have been made on the habits or food of Streptaxis, Rhytida, Ennea, Daudebardia, Paryphanta, and other carnivorous Mollusca. A specimen of Hnnea sulcata, enclosed in the same box as a Madagascar Helix (sepulchralis Fér.) many times its own size, completely emptied the shell of its inhabitant.2. Mr. E. L. Layard informs me that certain Cape Rhytida, eg. R. capsula Bens., R. dumeticola Bens., and R. vernicosa Kr., eat Cyclostoma affine, Helix capensis, H. cotyle- donis, etc. To Mr. Layard I am also indebted for the — perhaps apocryphal — tradition that the best time to capture the great 1 Erjavec, Nachr. Deutsch. Malak. Gesell. 1885, p. 88. 2 Crosse, Journ. de Conch. (8) xiv. (1874) p. 228. II HABITS OF CARNIVOROUS SNAILS AND SLUGS 55 Aerope caffra Fér. in numbers was after an engagement between the Kaffirs and Zulus, when they might be observed streaming from all points of the compass towards the field of slaughter. The Cuban Oleacina are known to secrete a very bitter fluid which they emit; this perhaps produces a poisoning or benumb- ing effect upon their victims when seized. They devour oper- culates, e.g. Helicona regina and sagraiana.1 1C. Wright, Zoologist, 1869, p. 1700. CHAPTER III ENEMIES OF THE MOLLUSCA — MEANS OF DEFENCE — MIMICRY AND PROTECTIVE COLORATION — PARASITIC MOLLUSCA — COMMENSALISM — VARIATION Enemies of the Mollusca THE juicy flesh and defenceless condition of many of the Mollusca make them the favourite food and often the easy prey of a host of enemies besides man. Gulls are especially partial to bivalves, and may be noticed, in our large sandy bays at the recess of the tide, busily devouring Tellina, Mactra, Mya, Syn- dosmya, and Solen. On the Irish coast near Drogheda a herring gull has been observed! to take a large mussel, fly up with it in the air over some shingly ground and let it fall. On alighting and finding that the shell was unbroken it again took it up and repeated the process a number of times, flying higher and higher with it until the shell was broken. Hooded crows, after many unavailing attempts to break open mussels with their beak, have been seen to behave in a similar way.2 Crows, vultures, and aquatic birds carry thousands of mussels, etc., up to the top of the mountains above Cape Town, where their empty shells lie in enormous heaps about the cliffs.? The common limpet is the favourite food of the oyster- catcher, whose strong bill, with its flattened end, is admirably calculated to dislodge the limpet from its seat on the rock. When the limpet is young, the bird swallows shell and all, and it has been calculated that a single flock of oyster-catchers, frequenting a small Scotch loch, must consume hundreds of 1W.V. Legge, Zoologist, 1866, p. 190. 2 Blackwall, Researches, p. 139. 3 Barrow, Travels in South Africa, ii. p. 67. 56 CHAP. II BIRDS, RATS, AND LIMPETS 57 thousands of limpets in the course of a single year. Rats are exceedingly fond of limpets, whose shells are frequently found in heaps at the mouth of rat holes, especially where a cliff shelves gradually towards a rocky shore. A rat jerks the limpet off with a sudden movement of his powerful jaw, and, judging from the size of the empty shells about the holes, has no difficulty in dislodging the largest specimens. ‘I once landed,’ relates a shepherd to Mr. W. Anderson Smith,! ‘on the I. of Dunstaff- nage to cut grass, and it was so full of rats that I was afraid to go on; and the grass was so full of limpets that I could scarcely use the scythe, and had to keep sharpening it all the time.’ Sometimes, however, the limpet gets the better both of bird and beast. ‘The same writer mentions the case of a rat being caught by the lip by a limpet shell, which it was trying to dislodge. A workman once observed? a bird on Plymouth breakwater flut- tering in rather an extraordinary manner, and, on going to the spot, found that a ring dotterel had somehow got its toe under a limpet, which, in closing instantly to the rock, held it fast. Similar cases of the capture of ducks by powerful bivalves are not uncommon, and it is said that on some parts of the American coasts, where clams abound, it is impossible to keep ducks at all,? for they are sure to be caught by the molluscs and drowned by the rising tide. e The Weekly Bulletin of San Francisco, 17th May 1898, con- tains an account of the trapping of a coyote, or prairie wolf, at Punta Banda, San Diego Co., by a Haliotis. Cracherodii. The coyote had evidently been hunting for a fish breakfast, and finding the Haliotis partially clinging to the rock, had inserted his muzzle underneath to detach it, when the Haliotis instantly closed down upon him and kept him fast prisoner. Rats devour the ponderous Uniones of North America. When Unio moves, the foot projects half an inch or more beyond the valves. If, when in this condition, the valves are tightly pinched, the foot is caught, and if the pinching is con- tinued the animal becomes paralysed and unable to make use of the adductor muscles, and consequently flies open even if the pressure is relaxed. The musk-rat (fiber zibethicus) seizes the Unio in his jaws, and by the time he reaches his hole, the Unio 1 Loch Creran, p. 102. 2 Cordeaux, Zoologist, 1873, p. 3396. 3 Amer. Nat. xii. p. 695; Science Gossip, 1865, p. 79. 58 ENEMIES OF SLUGS AND SNAILS CHAP. is ready to gape! Rats also eat Vivipara, and even Limnaea, in every part of the world. Every kind of slug and snail is eaten greedily by blackbirds, thrushes, chaffinches, and in fact by many species of birds. A thrush will very often have a special sacrificial stone, on which he dashes the shells of Helix aspersa and nemoralis, holding them by the lip with his beak, until the upper whorls are broken; heaps of empty shells will be found lying about the place of slaughter. The bearded Titmouse (Parus biarmicus) consumes quantities of Succinea putris and small Pupa, which are swal- lowed whole and become triturated in the bird’s stomach by the aid of numerous angular fragments of quartz.? Frogs and toads are very partial to land Mollusca. A garden attached to the Laboratory of Agricultural Chemistry at Rouen had been abandoned for three years to weeds and slugs. The director introduced 100 toads and 90 frogs, and in less than a month all the slugs were destroyed, and all kinds of vegetables and flowers, whose cultivation had until then been impossible, were enabled to flourish.® . Certain Coleoptera are known to prey upon Helices and other land Mollusca. Récluz noticed, near Agde, a beetle (Staphylinus olens) attack Helix ericetorwum when crawling among herbage, sticking its sharp mandibles into its head. Every time the snail retreated into its shell the beetle waited patiently for its reappearance, until at last the snail succumbed to the repeated assaults. M. Lucas noticed, at Oran, the larva of a Drilus attacking a Cyclostoma. The Drilus stood sentinel at the mouth of a shell, which was closed by the operculum, until the animal began to issue forth. The Drilus then with its mandibles cut the muscle which attaches the operculum to the foot, disabling it sufficiently to prevent its being securely closed, upon which it entered and took possession of the body of its de- fenceless host, completing its metamorphosis inside the shell, after a period of six weeks. The female glow-worm (Lampyris noctiluca) attacks and kills Helix nemoralis. Among the Clavicornia, some species of Silpha carry on a determined warfare against small Helices. They seize the shell 1 Journ. Trent. N. H. Soc. 1887, p. 58. 2 Ann. Nat. Hist. iii. 1898, pp. 2388, 239. 8 Rev. Nat. Sc. Ouest, 1891, p. 261. 4 Petit de la Saussaye, Journ. de Conch. iii. p. 97 £. Ill ENEMIES OF SLUGS AND SNAILS 59 in their mandibles, and then, throwing their head backwards, break the shell by striking it against their prothorax. The common water beetle, Dytiscus marginalis, from its strength and savage disposition, is a dangerous enemy to fresh- water Mollusca. One Dytiseus, kept in an aquarium, has been noticed to kill and devour seven Limnaea stagnalis in the course of one afternoon. The beetles also eat L. peregra, but appar- ently prefer stagnalis, for when equal quantities of both species were placed within their reach, they fixed on the latter species first. In East Africa a species of Ichneumon (/erpestes fasciatus) devours snails, lifting them up in its forepaws and dashing them down upon some hard substance.2 In certain islands off the south coasts of Burmah, flat rocks covered with oysters are laid bare at low tide. A species of Monkey (Macacus cynomolgus) has been noticed to furnish himself with a stone, and knock the oysters open, always breaking the hinge-end first, and then pull- ing out the mollusc with his fingers.® The walrus is said to support himself almost entirely on two species of Mya (truncata and arenaria), digging them out of the sand, in which they live buried at a depth of about 14 feet, with his powerful tusks. Whales swallow enormous numbers of pelagic molluscs (Clio, Limacina), which are at times so abundant in the Arctic seas, as to colour the surface for miles. Many of the larger Cetacea subsist in great part on Cephalo- poda; as many as 18 lbs. of beaks of Teuthidae have been taken from the stomach of a single yperoodon. Fish are remarkably partial to Mollusca of various kinds. The cat-fish (Chimaera) devours Pectunculus and Cyprina, erushing the stout shells with its powerful jaws, while flounders and soles content themselves with the smaller Tellina and Syn- dosmya which they swallow whole. As many as from 30 to 40 Specimens of Brccinum undatum have been taken from the stomach of a single cod, and the same ‘habitat’ has been re- corded for some of the rarer whelks, e.g. Buce. humphreysianum, Fusus fenestratus, the latter also occurring as the food of the haddock and the red gurnard. No less than 35,000 Turtonia minuta have been found in the stomach of a single mullet. 1J. W. Williams, Science Gossip, 1889, p. 280. 2 Noack, Zool. JB. ii. p. 254. 8 La Nature, xv. (2) p. 46. 60 MOLLUSCA AS FOOD FOR FISH AND FOR ONE ANOTHER cu. Nudibranchs are no doubt dainty morsels for fish, and hence have developed, in many cases, special faculties for concealment, or, if distasteful, special means of remaining conspicuous (see pp. 71-74). Besides the dangers to which they are exposed from other enemies, many of the weaker forms of Mollusca fall a prey to their own brethren. Vassa and Murex on this side of the At- lantic, and Urosalpinx on the other, are the determined foes of the oyster. Purpura lapillus prefers Mytilus edulis to any other food, piercing the shell in about two days’ time by its powerful radula, which it ap- pears to employ somewhat in gimlet fashion. If Mytilus Fig. 22.— Two valves of Mytilus edulis cannot be procured, it will eat L., representing diagrammatically 5 3 ser’ the approximate position of the Inttorina or Trochus, but its holes bored by Purpura in about attempts on the hard shell of 100 specimens of Mytilus, gathered 5 at Newquay, Cormwall. Patella are generally failures. | The statement which is some- times made, that the Purpura makes its hole over the vital -parts of the Mytilus, appears, according to the evidence embodied in the annexed figure, to be without foundation. The fact is that a hole in any part of its shell is fatal to the Mytilus, since the long proboscis of the Purpura, having once made an entrance, can reach from one end of the shell to the other. The branchiae are first attacked, the adductor muscles and edges of the mantle last. Matica and Nassa pierce in a similar way the shells of Mactra, Tellina, Donax, and Venus. Murex fortispina is fur- nished with a powerful tooth at the lower part of its outer lip. At Nouméa, in New Caledonia, its favourite food is Arca pilosa, which lives half buried in coral refuse. The Murex has been seen to drag the Arca from its place of concealment, and insert the tooth between the valves, so as to prevent their closing, upon which it was enabled to devour its prey at leisure.! The carnivorous land Mollusca, with the exception of Testa- cella, appear to feed by preference upon other snails (pp. 54, 55). 1 Frangois, Arch. Zool. Hup. Gén. (2) ix. p. 240. II WORMS PARASITIC IN MOLLUSCA 61 Parasitic Worms, Mites, etc. — A considerable number of the Trematode worms pass one or more of the stages in the _eycle of their development within the bodies of Mollusca, attain- ing to the more perfect or sexual form on reaching the interior of some vertebrate. Thus Distoma endolabum Duj. finds its first intermediate host in Limnaea stagnalis and L. ovata, its second in L. stagnalis, or in one of the fresh-water shrimps (Gammarus pulex), or in the larvae of one of the Phryganeidae (Limnophilus rhombicus), attaining to the sexual form in the common frog. Distoma ascidia v. Ben. passes firstly through Limnaea stagnalis or Planorbis corneus, secondly through certain flies and gnats (Ephemera, Perla, Chironomus), and finally arrives within certain species of bats. Distoma nodulosum Zed. inhabits firstly Paludina impura, secondly certain fishes (Cyprinus Acerina), and lastly the common perch. The sporocyst of Dis- toma macrostomum inhabits Succinea putris, pushing itself up into the tentacles, which become unnaturally distended (Fig. 23). Fic. 23.—A Trematode While in this situation it is swallowed by RCs various birds, such as the thrush, wagtail, __ sitic in the tentacles of and blackbird, which are partial to Suecinea, pg as ee a and thus obtains lodgment in their bodies. Amphistoma subclavatum spends an early stage in Planorbis con- tortus, after which it becomes encysted on the skin of a frog. When the frog sheds its skin, it swallows it, and with it the Am- phistoma, which thus becomes established in the frog’s stomach.! The common liver-fluke, which in the winter of 1879-1880 cost Great Britain the lives of no less than three million sheep, is perhaps the best known of these remarkable parasitic forms of life. Its history shows us, in one important particular, how essential it is for the creature to meet, at certain stages of its existence, with the exact host to which it is accustomed. Unless the newly-hatched embryo finds a Limnaea truncatula within about eight hours it becomes exhausted, sinks, and dies. It has been tried with all the other common pond and river Mollusca, with Limnaea peregra, palustris, auricularia, stagnalis, with Planorbis marginatus, carinatus, vortex, and spirorbis, with Physa fontinalis, Bithynia tentaculata, Paludina vivipara, as 1A. Lang, Ber. Naturf. Ges. Freib. vi. 1892, p. 81. 62 WORMS PARASITIC IN MOLLUSCA CHAP. well as with Succinea putris, Limax agrestis and maximus, Arion ater and hortensis. Not one of them would it touch, except occasionally very young specimens of ZL. peregra, and in these its development was arrested at an early stage. But on touch- ing a L. truncatula the embryo seems to know at once that it has got what it wants, and sets to work immediately to bore its way into the tissues of its involuntary host, making by pref- erence for the branchial chamber; those which enter the foot or other outlying parts of the Limnaea proceed no farther.? Many similar cases occur, in which littoral Mollusca, such as Littorina and Buccinum, form the intermediate host to a worm which eventually arrives within some sea-bird. Certain Nematode worms (Rhabditis) are known to inhabit the intestine of Arion, and the salivary glands of Limaz agrestis. Diptera habitually lay their eggs within the eggs of Helix and Limax. Many species of mite (Acarina) infest land Pulmonata. No adult Limax maximus is without at least one specimen of Philodromus (?) limacum, and the same, or an allied species, appears to occur on the larger of our Helices, retiring upon occasion into the pulmonary chamber. Several of the Crustacea live associated with certain molluscs. Pinnotheres lives within the shell of Pinna, Ostrea, Astarte, Pectunculus, and others. Apparently the females alone reside within the shell of their host, while the males seize favourable opportunities to visit them there. A specimen of the great pearl-oyster (Meleagrina margaritifera) was recently observed which contained a male Pinnotheres encysted in nacre. It was suggested that he had intruded at an unfortunate time, when no female of his kind happened to be in, and that, having penetrated too far beneath the mantle in the ardour of his search, was made prisoner before he could escape.2 Ostracotheres Tridacnae lives in the branchiae of the great Tridacna. A little brachyurous crustacean inhabits the raft of Janthina, and assumes the brill- iant blue colour of the mollusc. Means of Defence As a rule, among the Mollusca, the shell forms a passive mode of resistance to the attacks of enemies. Bivalves are 1A. P. Thomas, Q. J. Micr. Sc. N. S. xxiii. (1883) p. 99. 2H. Woodward, P. Z. S. 1886, p. 176. II TEETH IN APERTURE OF SNAILS 63 enabled, by closing their valves, to baffle the assault of their smaller foes, and the operculum of univalves, both marine and land, serves a similar purpose. Many land Mollusca, especially Helix and Pupa, as well as a number of Aurieulidae, have the inside of the aperture beset with teeth, which are sometimes so numerous and so large that it is puzzling to understand how the animal can ever come out of its shell, or, having come out, can ever draw itself back again. Several striking cases of these toothed apertures are given in Fig. 24.. Whatever may be the Fig. 24. —Illustrating the elaborate arrangement of teeth in the aperture of some land Pulmonata. A. Helix (Labyrinthus) bifurcata Desh., Equador. B. 4H. (Pleurodonta) picturata Ad., Jamaica. C. H. (Dentellaria) nux denticulata Chem., Demerara. D. Anostoma carinatum Pfr., Brazil; a, tube communicating with interior of shell. E. H. (Stenotrema) stenotrema Fér., Tennessee, X 3. F. H. (Polygyra) auriculata Say, Florida, x 3%. G. H. (Plectopylis) refuga Gld., Tenasserim (a and b x 2). origin of these teeth, there can be little doubt that their extreme development must have a protective result in opposing a barrier to the entrance, predatory or simply inquisitive, of beetles and other insects. Sometimes, it will be noticed (G), the aperture itself is fairly simple, but a formidable array of obstacles is encountered a little way in. It is possible that the froth emitted by many land snails has a similar effect in involving an irritating intruder in a mass of sticky slime. The mucus of slugs and snails, on the other hand, is more probably, besides its use in facilitating locomotion, a contrivance for checking evaporation, by surrounding the exposed parts of their bodies with a viscid medium. Some species of Zima shelter themselves in a nest constructed of all kinds of marine refuse, held together by byssiferous threads. 64 MEANS OF CONCEALMENT CHAP. Modiola adriatica, M. barbata, and sometimes M. modiolus con- ceal themselves in a similar way. (Grastrochaena frequently encloses itself in a sort of half cocoon of cement-like material. The singular genus Xenophora protects itself from observation by gluing stones, shells, and various débris to the upper side of its whorls (Fig. 25). Sometimes the selection is made with remarkable care; the Challenger, for instance, obtained a speci- men which had decorated its body whorl exclusively with long and pointed shells (Fig. 26). Fic. 25.— Xenophora (Phorus) conchyliophora Born., con- Fic. 26. — Xenophora (Phorus) pallidula Reeve. cealed by the stones which A molluse which escapes detection by cover- it glues to the upper surface ing itself with dead shells of other species. of its shell. (From a British (From a Challenger specimen in the British Museum specimen.) Museum, X3.) The formidable spines with which the shells, e.g. of the Murex family, are furnished must contribute greatly to their protection against fishes, and other predatory animals. Murex tenuispina, for instance (see chap. ix.), would prove as dangerous a morsel in the mouth of a fish as a hedgehog in that of a dog. Whether the singular tooth in the outer lip of Leucozonia (see chap. xiv.), a feature which is repeated, to a less marked extent, in Monoceros and several of the West Coast muricoids, is devel- oped for defensive purposes, cannot at present be decided. The Strombidae possess the power of executing long leaps, which they doubtless employ to escape from their foes. In their case alone this power is combined with singular quickness of vision. On one occasion Mr. Cuming, the celebrated collector, lost a beautiful specimen of Terebellum, by the animal suddenly III MEANS OF DEFENCE 6 5 leaping into the water, as he was holding and admiring it in his hand. Miss Saul has informed me that the first living specimen of Trigonia that was ever obtained was lost ina similar way. It was dredged by Mr. Stutchbury in Sydney Harbour, and placed on the thwart of a small boat. He had just remarked to a companion that it must be a Zrigonia, and his companion had laughed at the idea, reminding him that all known Trigonia. were fossil, when the shell in question baffled their efforts to discover its generic position by suddenly leaping into the sea, and it was three months before Mr. Stutchbury succeeded in obtaining another. Some genera possess more than merely passive means of defence. Many Cephalopoda emit a cloud of inky fluid, which is of a somewhat viscous nature, and perhaps, besides being a means of covering retreat, serves to entangle or impede the pursuer. The formidable suckers and hooks possessed by many genera in this Order are most dangerous weapons, both for offence and defence. Aplysta, when irritated, ejects a purple fluid which used to be considered dangerously venomous. Many of the Aeolididae, including our own common Aeolis papillosa, possess stinging cells at the end of their dorsal papillae, the effect of which is apes: to render them exceedingly distasteful to fish. The common Vitrina pellucida has a curious habit which in all probability serves for a defence against birds in the winter. When crawling on the edge of a stone or twig it has the power of suddenly jerking its ‘ tail,’ so as to throw itself on the ground, where it is probably lost to sight among decaying leaves. At other times it rolls away a few inches and repeats the jump. It also possesses the power of attaching to itself bits of leaves or soil, which entirely cover and conceal both shell and animal.! The property of parting with the tail altogether, a remarkable form of self-defence, has already been noticed on p. 44. The poisonous nature of the bite of certain species of Conus ¥ is well authenticated. Surgeon Hinde, R.N., saw? a native on the I. of Matupi, New Britain, who had been bitten by a Conus geographus, and who had at once cut small incisions with a sharp stone all over his arm and shoulder. The blood flowed freely, 1W. KH. Collinge, Zoologist, 1890, p. 467. 2 Proc. Linn. Soc. N. S. Wales, ix. p. 944. VOL. Ill Rr 66 POISONOUS BITE OF CONUS CHAP. and the native explained that had he not taken these precautions he would have died. Instances have been re- corded of poisonous wounds being inflicted by the bite of Conus aulicus, C. textile, and C. tulipa. According to Mr. J. Macgillivray! C. textile at Aneitum (S. Pacific) is called intrag, and the natives say it spits the poison upon them from several inches off! Two cases of bites from C. textile occurred to this gentleman’s notice, one of which terminated fatally by gangrene. Sir Ed- ward Belcher, when in command of the Samarang, was bitten? by a Conus aulicus at a little island off Ternate in the Moluccas. As he took the creature out of the water, it suddenly exserted its proboscis and inflicted a wound, causing a sensa- tion similar to that produced by the burning of phosphorus under the skin. The wound was Fic.27.—Atooth a small, deep, triangular mark, succeeded by a sc erenaee: watery vesicle. The natives of New Guinea have rialis L., x 50, a wholesome dread of the bite of Cones. Mr. C. a caeaticee Hedley relates* that while collecting on a coral reef he once rolled over a boulder and exposed a living C. textile. Before he could pick it up, one of the natives hastily snatched it away, and explained, with vivid gesticula- tions, its hurtful qualities. On no account would he permit Mr. Hedley to touch it, but insisted on himself placing it in the bottle of spirits. Mimicry and Protective Coloration. Cases of Mimicry, or protective resemblance, when a species otherwise defenceless adopts the outward appearance of a better protected species, are rare among the Mollusca. Karl Semper* mentions an interesting case of the mimicry of Helicarion tigri- nus by Xesta Cwmingti, in the Philippines. It appears that all 1 Zoologist, xviii. (1860) p. 7136. 2A. Adams, Samarang, vol. ii. Zoology, p. 357. 3 In Thomson’s British New Guinea, p. 283. 4 Animal Life, p. 395. It should be mentioned that Von Méllendorff (Ber. Senck. Ges. 1890, p. 198) ridicules the whole theory. —" UI MIMICRY 67 species of Helicarion possess the singular property of shaking off the ‘tail’ or hinder part of the foot, when seized or irritated. Specimens captured by collectors, Hel. tigrinus amongst them, have succeeded in escaping from the hand, and concealing them- selves, by a sort of convulsive leap, among the dry leaves on the ground. This power of self-amputation must be of great value to Helicarion, not only as enabling it to escape from the clutch of its enemies, but also as tending to discourage them from attempting to capture it at all. Now the genus Xesta is, in anatomy, very far removed from Helicar‘on, and the majority of the species are also, as far as the shell is concerned, equally distinct. Xesta Cumingii, however, has, according to Semper, assumed the appearance of a Helicarion, the thin shell, the long tail, and the mantle lobes reflected over the shell; but it has not the power of parting with its tail at short notice. It lives asso- ciated with Helicarion, and so close is the resemblance between them that, until Semper pointed out its true position, it had always been classified as a member of that group. In the same passage Semper draws attention to two other cases of apparent mimicry. The first is another species of Xesta (mindanaensis) which closely resembles a species of hysota (Antoniz), a genus not indeed so far removed from Xesta as Helicarion, but, as far-as the shell is concerned, well distin- guished from it. In this case, however, there is no obvious advantage gained by the resemblance, since Rhysota as com- pared with Xesta is not known to possess any definite point of | superiority which it would be worth while to counterfeit. A second case of resemblance between certain species of the genus Chloraea and the characteristic Philippine group Cochlostyla will not hold good as affording evidence of mimicry, for Chlo- raea is now recognised as a subgenus of Cochlostyla. The Mollusca are not much mimicked by creatures of dif. ferent organisation. This appears at first sight strange, since it might have been thought that the strong defensive house of a snail was worth imitating. Still it is probably not easy for creatures bilaterally symmetrical to curl themselves up into an elevated spiral for any length of time. One or two instances, however, may be mentioned. The larva of a moth belonging to the Psychidae, and occurring in France, Germany, the Tyrol, and Syria, coils itself up into a sinistral spiral of three whorls, 68 MIMICRY . CHAP, and is aptly named Psyche helix, a kindred species from Italy being known as Ps. planorbis. An insect larva (Cochlophora valvata) from E. Africa is said to resemble a Valvata or young Cyclostoma. In this case the spiral is indifferently dextral or sinistral, the ‘shell’ being formed of masticated vegetable matter, united together by threads spun by the larva. Certain larvae of the Phryganeidae (“* Caddis-worms ’”) enclose themselves in houses which more or less resemble a spiral shell, and have in some cases actually been described as molluscan; such species, some of which belong to Helicopsyche, have been noticed in 8. Europe, Ceylon, Further India, China, Tasmania, New Zealand, Tennessee, Mexico, Cen- tral America, Venezuela, Brazil, and Argentina, and all? possess a dextral ‘shell.’ In all these cases ‘mimicry’ is probably not so much to be thought of as the practical advantages which accrue to the animal in question from the spiral form, which gives it greater strength to resist external blows, and enables it to occupy, during a very defenceless portion of its existence, a very small amount of space. The larva of some species of the Syrphidae (Diptera) fixes itself on the under side of stones in the Tyrol, and closely resembles a small slug. The naturalist Von Spix, in 1825, described to the Bavarian Academy as a new genus of land Mol- lusca a somewhat similar larval form found in decaying wood on the banks of a German lake. Simroth mentions? a curious case as occurring near Grimma. The caterpillars of certain Microlepidoptera occur on slabs of porphyry, associated with a species of Clausilia. Besides being of the same colour as the Clausiliae, the caterpillars have actually developed cross lines on the back, 7.e. on the side turned away from the rock, in imi- tation of the suture of the mollusc. It has been suggested ¢ that there is mimicry between Aeolis papillosa (a common British nudibranch) and Sagartia troglo- dytes (an Actinian), and also between another species of Sagartia and Aeolidiella Alderi. The facts observed are not sufficient to warrant a decided opinion, but it seems more proba- 1'Von Martens, SB. Nat. Fr. Berl. 1891, p. 83. 2 Von Martens, ibid. 1887, p. 183. 3 SB. Nat. Gesell. Leipz. xiii.—xiv. p. 46. 4 Garstang, Journ. Mar. Biol. Ass. N. S. i. p. 482; Giard, Bull. Sci. Fr. Belg. 1888, p. 502 f. III MIMICRY 69 ble that the Actinian mimics the nudibranch than vice versé, since Aeolis is known to be unpalatable to fishes. Certain species of Strombus (mauritianus L., luhuanus L.) show a remarkable similarity in the shape of the shell to that of Conus, so much so, that a tiro would be sure to mistake them, at first sight, for Cones. In the case of S. luh- uanus at least, this similarity is increased by the possession of a remarkably stout brown epidermis. Now Conus is a flesh-eating genus, armed with very powerful teeth which are capable of inflicting even Fig. 28.— A, Strombus mauritianus on man a poisonous and sometimes =Lam., which mimics Conus in fatal wound (see p. 66). Strombus, eo CRE es on the other hand, is probably fru- givorous, and is furnished with weak and inoffensive teeth. It is possible that this resemblance is a case of ‘mimicry.’ It is quite conceivable that powerful fishes which would swallow a Strombus whole and not suffer for it, might acquire a distaste for a Cone, which was capable of lacerating their insides after being swallowed. And therefore the more like a Cone the Strombus became, the better chance it would have of being passed over as an ineligible article of food. Protective coloration is not uncommon among ae Mollusca. Tittorina obtusata is habitually found, on our own coasts, on Fucus vesiculosus, the air-bladders of which it closely resembles in colour and shape. Littorina pagodus, a large and showy species, resembles so closely the spongy crumbling rocks of Timor, on which it lives, that it can hardly be discerned a pace off. Helcion pellucidum, the common British ‘blue limpet,’ lives, when young, almost exclusively on the iridescent leaves of the great Laminariae, with the hues of which its own conspicuous blue lines harmonise exactly. In mature life, when the Helcion invariably transfers its place of abode to the lower parts of the stalk and finally to the root of the Laminaria, which are quite destitute of iridescence, these blue lines disappear or become much less marked. The specimens of Purpura lapillus which occur at Newquay 70 PROTECTIVE COLORATION CHAP. in Cornwall are banded with rings of colour, especially with black and white, in a more varied and striking way than any other specimens that have ever occurred to my notice. I am inclined to refer this peculiarity to a tendency towards protec- tive coloration, since the rocks on which the Purpura occurs are. often banded with veins of white and colour, and variegated to a very marked extent. Ovula varies the colour of its shell from yellow to red, to match the colour of the Gorgonia on which it lives. The same is the case with Pedicularia, which occurs on red and yellow coral. Helix desertorum, by its gray-brown colour, harmonises well with the prevailing tint of the desert sands, among which it finds a home. Benson observes that the gaudy H. haemastoma, which lives on the trunks of palm-trees in Ceylon, daubs its shell with its excrement. Our own Buliminus obscurus, which lives principally on the trunks of smooth-barked trees, daubs its shell with mud, and must often escape the observation of its enemies by its striking resemblance to the little knots on the bark, especially of beech trees, its favourite haunt. Some species of Microphysa, from the West Indies, habitually encrust their shells with dirt, and the same peculiarity in Vetrina has already been mentioned. Ariophanta Dohertyi Aldr., a recent discovery from Sumatra, is of a green colour, with a singularly delicate epidermis; it is arboreal in its habits, and is almost invisible amongst the foliage.’ Many of our own slugs, according to Scharff, are coloured protectively according to their surroundings. Gould, Moll. of U. 8. expl. exped. 1852, p. 207 (St. acicula, from Fiji). 6 Stimpson, Proc. Bost. Soc. N. H. vi. 1858, p. 308. 7 Pidgeon, Nature, xxxix. p. 127. 78 MOLLUSCA PARASITIC ON MOLLUSCA CHAP. under the carapace of the common shore-crab (Carcinus mae- nas), and one case has been noticed’ where two mussels, one of several months’ growth, the other smaller, well secured by their. byssi, were found under the abdomen of the same species, in such a position as to force the appendages apart and askew. These, however, are not so much cases of para- sitism as of involuntary habitat, the mussel no doubt having become involved in the branchiae and the abdomen of the crab in the larval form. On Mollusca. — A species of Odostomia (pal- lida Mont.) is found on our own coasts on the ‘ears’ of Pecten maximus, and also? on the oper- culum of Turritella communis. Another species Wy} Fic. 30. — Crepidu- : : : ae in ue Sey (O. rissoides) frequently occurs in hiding under bonnie on py beds of mussels, but it is not clear whether the operculum oO ° . site 3 eo hie gale. habitat is due to parasitism, or simply to the atus Swains., fact that the mass of mussels, knitted together Panama. and to the rock by the byssi, affords the Odosto- mia a safe lurking-place. At Panama the present writer found Crepidula (2 sp.) plentiful on the opercula of the great Strom- bus galea and of Cerithiwm irroratum. In each case the parasite exactly fitted the size of the operculum, and had assumed its colour, dark brown or chestnut. Amalthea is very commonly found on Conus, Turbo, and other large shells from the South Pacific, but this is probably not a case of parasitism, but simply of convenience of habitat, just as young oysters are frequently seen on the carapace and even on the legs of large crabs. On Tunicata.— Lamellaria deposits its eggs and lives on an Ascidian (Leptoclinum), and the common Modiolaria marmorata lives in colonies imbedded in the test of Ascrdia mentula and other simple Ascidians. Special points of interest with regard to parasitic Mollusca relate to (1) Colour. This is in most cases absent, the shell being of a uniform hyaline or milky white. This may be due, in the case of the endo-parasitic forms, to absence of light, and possibly, in those living outside their host, to some deficiency in the nutritive material. A colourless shell is not necessarily pro- 1W. Anderson Smith, Loch Creran, p. 46. 2 Smart, Journal of Conch. v. p. 152. Ill COLOUR OF PARASITIC MOLLUSCA 79 tective, for though a transparent shell might evade detection, a milk-white hue would probably be conspicuous. (2) Modifica- tions of structure. These are in many cases considerable. Ento- concha and Entocolax have no respiratory or circulatory organs, and no known nervous system ; Thyea and certain Stilifer possess a curious suctorial apparatus; the foot in many cases has aborted, since the necessity for locomotion is reduced to a minimum, and its place is supphed by an enormous development of the proboscis, which en- ables the creature to provide itself with nutriment without shifting its position. | K. Semper notices a case where a Hu- lima, whose habitat is the stomach of a F!. 31.—Two species of Zu- : ; ‘ lima: Aissessile on the skin Holothurian, retains the foot unmodified, of a Holothurian, through while a species occurring on the outer Which it plunges its sucking : 3 ; : proboscis (Pr); B creeps skin, but provided with along proboscis, freely in the stomach of has lost its foot altogether Special Saas (After, K. aa per.) provision for holding on is noticed in certain cases, reminding us of similar provision in human para- sites. Eyes are frequently, but not always wanting, even in endo-parasitic forms. A specially interesting modification of structure occurs in (8) the Radula or ribbon-shaped arrange- ment of the teeth. In most cases of parasitism (Hulima, Stilifer, Odostomia, Entoconcha, Entocolax, Magilus, Coralliophila, Lepto- concha) it is absent altogether. In Ovula and Pedieularia, genera which are in all other respects closely allied to Cypraea, the radula exhibits marked differences from the typical radula of the Cypraeidae. The formula (3-1:3) remains the same, but the laterals are greatly produced and become fimbriated, some- times at the extremity only, sometimes along the whole length. A very similar modification occurs in the radula of Sistrum spectrum Reeve, a species which is known to live parasitically on one of the branching corals. Here the laterals differ from those of the typical Purpuridae in being very long and curved at the extremity. The general effect of these modifications ap- pears to be the production of a radula rather of the type of the vegetable-feeding Trochidae, which may perhaps be regarded as 1 Animal Life, p. 351. A 8o CASES OF COMMENSALISM CHAP. a link in the chain of gradually-degraded forms which event- ually terminate in the absence of the organ altogether. The softer the food, the less necessity there is for strong teeth to tear it; the teeth either become smaller and more numerous, or else longer and more slender, and eventually pass away alto- gether. It is curious, however, that the same modified form of radula should appear in species of Ovula (e.g. ovwm) and that the same absence of radula should occur in species of Hulima (e.g. polita) known to be not parasitic. This fact perhaps points back to a time when the ancestral forms of each group are parasitic and whose radulae were modified or wanting, the modification or absence of that organ being continued in some of their non-parasitical descendants. Commensalism Mollusca are concerned in several interesting cases of com- mensalism, or the habitual association of two organisms, as dis- » tinguished from parasitism, where one form preys more or less upon the other. Mr. J. T. Marshall has given?! an interesting account of the association of Montacuta ferruginosa with Hehinocardium cor- datum. 'The Echinoderm lives in muddy sand in Torbay, at a depth of about 6 inches, and the Montacuta lives in a burrow leading from its ventral end and running irregularly in a sloping direction for 8 or 4 inches, the burrow, which is made by a ° current from the Echinoderm, being almost exactly the width of the Montacuta. The Montacuta were always arranged in the burrows in order of size, the largest being close to the Echino- derm, and the smallest of a string of about six at the other end of the burrow. In another part of S. Devon, where the sand was soft and sloppy, the Echinocardia rise to the surface and travel along the sand; in this case the Montacuta were attached to their host by means of a byssus, and were dragged along as it travelled. The Rev. Dr. Norman has noted? a somewhat similar habitat for Lepton squamosum. This rare little British species was found at Salcombe, living in the burrows of Gebia stellata, in all probability feeding upon the secretions from the body of the 1 Journ. of Conch. vi. 1891, p. 899. 2 Ann. Mag. N. H. (6) vii. p. 276. Ul CASES OF COMMENSALISM 81 crustacean. Dr. Norman suggests that the extreme flatness of the shell of the Lepton is of great advantage in enabling it not to get in the way of the Gebdza as he scuttles up and down his burrow. Another species of Lepton is found on the coast of Florida in a precisely similar locality! while a third species, occurring on the Oregon and California coasts, actually attaches itself to the inner surface of the abdomen of a Gebza.? A very singular case of commensalism has been recently dis- covered with regard to a genus of Australian bivalve shells, Ephippodonta. This genus is never found except in the burrow of a species of prawn (Avzius plectorhynchus Str.). For some reason at present unexplained, the burrow of this particular prawn appears to be exceedingly popular as a habitat for certain bivalves, for, besides two species of Ephippodonta, a Kellia and Fic. 32.— Ephippodonta Mac- dougalli Tate, S. Australia. A, Burrow of prawn, the Xx indicating the position of the mollusc; sp, sponge. B, Ventral view of Ephippo- donta ; by, byssus; f, foot; m, mantle; mm, fused man- tle borders. C, View of in- terior of shells; h, hinge; m'm', adductor muscles. (A X 3; Band C x 2.) three Mylitta are found there, and there alone. Sometimes the prawn, when the rock is hard, builds a tunnel of mud upon it, at other times it excavates the soft calciferous sandstone. “ This burrow is lined with a tenacious brown mud, composed of excre- mentitious matter; and, in addition to the mud lining, there is _always more or less present an orange-coloured sponge which I have never found elsewhere. Upon the mud or sponge, and adhering very closely, are found the Hphippodonta. They quickly form a pit-like depression by means of their foot, and appear almost covered by the mud.” During the winter months 1 Stimpson, quoted by Jeffrey’s Brit. Conch. ii. 194. 2 Stimpson, Journ. Bost. Soc. N. H. vi. 1857, p. 48. VOL. Ill : PEG 82 VARIATION CHAP. (March—July) the prawn appears to fill his burrow, possibly as a provision against stormy weather, with large quantities of minced seaweed, underneath which immense numbers of very young Hphippodonta are found living.t The extreme flatness of the Hphippodonta must be due to the same cause as the flat- ness of the Lepton noticed above, namely, the necessity of not impeding or interfering with the lively motions of the prawn. In the case of Lepton the two valves close completely and the shell is still very flat; in Ephippodonta, on the other hand, the same result is produced by the valves being opened to their widest possible extent. As in Hntovalva, a continuation of the mantle covers the outer surface of the shell. Variation It is a familiar experience to the student, not only of the Mollusca, but of every branch of animal or vegetable life, to come across examples which exhibit certain slight deviations from the type form as usually understood. These deviations may be more or less pronounced, but, as a rule, a series of forms can be discovered, gradually leading up to or down from the type. The definition of what constitutes a species, — and, still more, the rigid application of such definition— will always remain a difficult task, so long as the personal element persists in him who defines.2~ What seems to one authority ample ground for distinction of species, another may regard as of comparatively trivial importance. The practical outcome of these divergent views is sufficiently illustrated by the attitude of Mr. F. P. Marrat on the one hand, and of what may be called the modern French school of conchologists on the other. Mr. Marrat holds, or held, that the great genus Nassa, of which more than 150 species are generally recognised, is one shell (species) in an endless variety of forms. The modern French school go to the other extreme, and apparently proceed upon the view that almost any difference in form, however slight, is sufficient to constitute a separate species. It will be generally admitted, however, that some structural 1K. H. Matthews, Conchologist, ii. p. 144. 2 Thus Limnaea involuta, which is almost universally regarded as a good and distinct species, has been held to be no more than a variety of Z. peregra pro- duced by locality ; see Zoologist, 1889, p. 154. III EFFECTS OF CHANGES IN THE ENVIRONMENT 83 difference in the organisation of the animal (as distinct from that of the shell alone) is necessary for the permanent constitution of specific rank.1 What amount of structural difference is required, what particular organ or organs must exhibit this difference, will depend largely upon the idiosyncrasy of the observer. But if this, or something like this definition of a species be accepted, it will follow that a so-called ‘variety’ will be a form which exhibits differences from the type which do not amount to per- manent structural differences in the organisation of the animal. The final court of appeal as to what affords sufficient evidence for ‘permanent structural differences’ will have to be, as with Aristotle of old, the judgment of the educated man. It is, however, more to our present purpose to discuss the causes of variation than to lay down definitions of what variation is. One of the most obvious causes of variation lies in a change -or changes in the environment. If we may assume, for the moment, that the type form of a species is the form which is the mean of all the extremes, and that this form is the resultant of all the varied forces brought to bear upon it, whether of food, climate, temperature, competition of numbers, soil, light, amount of water, etc., it will follow that any change in one or more of these forces, if continuous and considerable, any change, in other words, of the environment, will produce its effect upon the organism in question. And this effect will be for the better or for the worse, according to the particular nature of the change itself as tending towards, or away from, the optimum of environ- ment for the species concerned. Hence may be produced vari- eties, more or less marked according to the gravity of the change, although it must be noted that at times a change apparently unimportant from our point of view, will produce very marked results upon the species. It is indeed scarcely possible to predict with any certainty, inthe present state of our knowledge (beyond certain broad results) what will be the particular effect upon a Species of any given change in its surroundings. Effects of Change in the Environment as tending to produce Variation. (a) Changes in Climate, Temperature, Elevation, ete. — In the eastern basin of the Baltic the marine Mollusca are much more 1J. W. Taylor, Journ. of Conch. v. p. 289, an interesting article, with many useful references. 84 EFFECTS OF CHANGES IN THE ENVIRONMENT CHAP. stunted than in the western.! For instance, Mytilus edulis near Kiel is 8-9 cm. long, while near Gothland it only attains a length of 3-4 em. Mollusca living at only a shallow depth (e.g. Tellina balthica, Mya arenaria, Cardium edule) do not differ much in size in different parts of the Baltic, but in the far eastern basin the calcareous layers of the shells of Mya arenaria and Tellina balthica are extraordinarily thin, and disappear very rapidly after death, leaving only the cuticular membrane, still united by the ligament, in a perfect state of preservation. These remarkable variations are no doubt to a large extent due to the violent changes of temperature which are experienced in the Baltic, and by which the steady development of the animals in question is interrupted and thrown out of gear. The same spe- cies occur on the coasts of Greenland and Iceland, where they attain a considerably larger size than in the Baltic, in spite of the lower mean temperature, probably because their development is not interrupted by any sudden change from cold to heat or vice versa. Karl Semper has shown that Limnaea stagnalis is developed, lives and feeds best in a mean temperature of about 20° C. (=68° F.). This mean, however, must not be the mean of two distant extremes, for the Limnaea cannot digest its food and grow in a temperature which is less than 14° or 15° C. (=57° or 59° F.), or more than 80° to 32° C. (=86° to 90° F.). In certain localities, therefore, the interruption to the growth of this species must be serious and prolonged, and may tend towards the pro- duction of more or less dwarfed varieties. Thus specimens from Malham Tarn, a lake in Yorkshire 1250 feet above the sea, are permanently dwarfed, and have a very thin and fragile shell. Limnaea peregra in the Pyrenees, Alps, and Himalayas is gen- erally of a very delicate form and dwarfed habit, while the small variety known as lacustris occurs, according to Jeffreys, only in mountain lakes in Zetland, Scotland, Ireland, and N. England. Specimens brought by Mr. Bateson from lakes near the Sea of Aral, which are salt for some months and comparatively fresh for others, exhibit clearly the effect of changes in the environment (Figs. 83 and 84). Excess of heat produces similar results to excess of cold. L. peregra var. thermalis, found in the warm springs of the Pyrenees and the Vosges, and the var. gezsericola, 1 Mobius, Report on ‘ Pommerania’ Haped. pp. 138-141. III VARIATION DUE TO HEAT AND COLD 85 from the hot water of the Iceland geysers, are alike thin and dwarfed forms. Many instances may be given of ‘varieties due to locality.’ In some of these, the cause which predisposes towards variation can be inferred with some approach to certainty, in others we must be content to note the fact, without at present being able to perceive its explanation. Desert specimens of widely distributed species, e.g. Helix pomatia, H. niciensis, H. pisana, Leucochroa candidissima are much thicker than the type, and tend to lose all trace of coloured bands. These modifications are clearly the means of preventing evaporation of moisture, the dull white or grayish brown colour Fic. 33. — Four examples of Lim- naea peregra Mull., from salt marshes near the Sea of Aral, showing different effects pro- duced by abnormal] conditions of life. Fig. 34. — Four examples of Lim- naea stagnalis L., from marshes in the Aral district which are salt for several months in the year, illustrating variation pro- duced by changes in the envi- ronment. X 4. being calculated to absorb the smallest possible amount of heat. Desert shells in all parts of the world (e.g. N. Africa, Arabia, Central Asia, S. Africa, W. America) have been noticed to exhibit these peculiarities. A very singular case of the reverse process, 7.e. the produc- tion of darkened forms of shell through cold, has been noticed by Fischer as characteristic of the marine shells of the west coast of South America.t This melanism is especially noticeable in Trochus, Turbo, Chiton, Mitra, and Pleurotoma, and is attested by the specific names, not merely expressive of actual blackness (e.g. nigerrimus, ater, atramentarius, maurus), but also of a gen- erally lugubrious tone (e.g. moestus, funebralis, tristis, lugubris, luctuosus). It is highly probable that this concurrence of Specific melanism (which stands quite alone in the world) is 1 Journ. de Conchyl. xxiii. 1875, p. 105, 86 VARIATION IN SLUGS CHAP. due to the cold polar current which impinges on the Chilian coasts, for the same genera occur on the opposite shores of the continent without exhibiting any trace whatever of this mournful characteristic. It is a well-known fact, attested by many observers, that our common Limax agrestis as well as the young of Arion ater become decidedly darker in summer than in winter. If these slugs were accustomed to disport themselves in the sun, it might have been suggested that this increased darkness of colour tended to absorb more of the heat rays. But since this is not the case, the result is probably due to some unexplained effect of higher temperature. According to Lessona and Pollonera, the length of the keel in Limaz arborum varies greatly in different parts of Italy, being shorter in specimens from low ground, but much longer in those inhabiting more elevated regions. The longer the keel, the more obscure the colouring becomes, so that in the Upper Alps of Piedmont individuals are practically black. Roebuck has observed that Scottish specimens of this same slug are much darker and less translucent than English forms. According to Simroth, our common black slug, Arion ater, is a northern type, which in more southern latitudes assumes the form known as A. rufus. Similarly Zimax mazimus “in its northern form cinereo-niger is almost wholly black, but in the more genial climate of Italy develops a series of brilliantly coloured and strikingly marked variations which have received numerous distinctive names from Italian limacologists.”1 Ac- cording to Scharff, however? (who regards the colours of slugs as in the main protective), these dark forms are by no means exclusively northern, being found equally on the parched plains of Spain and Portugal, and in the bleak climate of Norway. The same authority observes that similar forms occur both in the dry regions of E. Germany, and in the very humid district of western Treland. It appears unquestionable that marine genera from high northern latitudes are provided with shells of uniform colour, or whitish with a pale brown epidermis; spots, bands, or stripes seldom occur. The arctic forms of Buccinwm, Trophon, Chryso- domus, Margarita, Crenella, Leda, Yoldia, Astarte illustrate this fact. In the more temperate seas of Europe, colours tend on the 1J, W. Taylor ut sup. p. 800. 2 Sci. Trans. KR. Dubl. Soc. (2) iv. p. 555. Ill VARIATION IN SNAILS 87 whole to increase, although there are certain genera (e.g. Pecten) which are not more brightly coloured in Mediterranean than in Icelandic waters. Land Mollusca inhabiting the mainland of a continent not unfrequently become smaller when they have spread to adjacent islands where perhaps the rainfall is less abundant or the soil and food-supply less nicely adjusted to their wants. Orthalicus undatus is decidedly larger on the mainland of 8. America than on the adjacent islands of Trinidad and Grenada. Specimens of Bulimulus exilis from Barbados are invariably broader and more obese than those from 8. Thomas, while those from the volcanic island of S. Lucia, where lime is deficient, are small and very slender. Streptaxis deformis, as occurring at Trinidad, is only half the size of specimens from Georgetown, Demerara.1 Certain localities appear, for some unexplained reason, to be particularly favourable to the production of albino varieties. The neighbourhood of Lewes, in Sussex, has produced no fewer than fourteen of these forms of land Mollusca and five of fresh-water.? Our common Helix aspersa, as found near Bristol, is said to be ‘dark coloured’; about Western-super-mare ‘ brown, with black markings’; near Bath ‘very pale and much mottled’; at Cheddar ‘very solid and large.’® Sometimes the same kind of variation is exhibited by different species in the same locality. Thus specimens of H. aspersa, H. nemoralis, and H. hortensis, taken from the same bank at Torquay, presented a straw-coloured tinge of ground colour, with red-brown bands or markings. Trochi- form H. nemoralis and H. arbustorum, sinistral. H. hortensis and HI. aspersa, sinistral H. aspersa and H. virgata, and similarly banded forms of H. caperata and H. virgata, have been taken together.* The immediate neighbourhood of the sea appears frequently to have the effect of dwarfing land Mollusca. Thus the var. conoidea of Helix aspersa, which is small, conical, with a com- pressed mouth, occurs ‘on sandhills and cliffs at the seaside.’ The varieties conica and nana of Helix hispida are found ‘near the sea.’ Helix virgata is exceedingly small in similar localities, and tends to become unicoloured. JH. caperata var. Gigazti, a 1J.S. Gibbons, Journ. of Conch. ii. p. 129. 4C. H. Morris, ibid. vii. p. 191. 3 F. M. Hele, ibid. iv. p. 93. 4T. D. A. Cockerell, Science Gossip, 1887, p. 67. 88 VARIATION IN SNAILS CHAP. small depressed form, occurs at ‘Sandwich and Falmouth.’ ! Sometimes, however, the exact opposite is the case, for H. nemoralis var. major, which is ‘much larger’ than the type, occurs on ‘ sandhills and downs’ and is ‘ remarkably large in the I. of Arran, Co. Galway.’ The dwarf form of Limnaea peregra known as maritima appears to be confined to the neighbourhood of the sea. Dwarfing of the shell seems frequently to be the result of an elevated locality, not perhaps so much as the direct consequence of purer air and less barometric pressure, as of changes in the character of the food supply and in the humidity of the air. Several species of Helix have a variety minor which is charac- teristic of an Alpine habitat. Helix arbustorum var. alpestris, which is scarcely two-thirds the size of the type, occurs on the Swiss Alps in the region of perpetual snow. Sometimes a very slight elevation is sufficient to produce the dwarfed form. At Tenby the type form of Helix pisana is scattered in countless numbers over the sandhills just above high-water mark. At the extreme western end of these sandhills rises abruptly to a height of over 100 feet the promontory known as Giltar Head, the vegetation of which is entirely distinct from that of the burrows below. There is a colony of H. pisana at the end of Giltar, all of which are devoid of the characteristic markings of the typical form, and most are dwarfed and stunted in growth. Occasionally the same variety will be found to be produced by surroundings of very different nature. Thus the var. alpes- tris, of H. arbustorum mentioned above, besides being character- istic of high Alpine localities, also occurs abundantly in low marshes at Hoddesdon on the River Lea. Helix pulchella var. costata, according to Jeffreys, is found in dry and sandy places, often under loose stones and bricks on walls, while other author- ities have noticed it in wet and dry localities quite indifferently. Sometimes the production of a variety may be traced to the intrusion of some other organism. According to Brot, nine- tenths of the Limaaea peregra inhabiting a certain pond near Geneva, were, during one season, afflicted with a malformation of the base of the columella. This deformity, coincided with the appearance, in the same waters, of extraordinary numbers of Hydra viridis. ‘The next season, when the Hydra disappeared, 1J. G. Jeffreys, British Conchology, vol. i. p. 214. ur VARIATION IN SNAILS _ | 89 the next generation of Limnaea was found to have resumed its normal form. It has been noticed that a form of Helix caperata with a flattened spire and wide umbilicus is restricted to tilled fields, especially the borders of clover fields, while a form with a more elevated spire and more compact whorls occurs exclusively in open downs and uncultivated places. The Rev. 8. 8. Pearce accounts ! for this divergence by the explanation that the flatter spire enables the shell of the fields to creep about more easily under the leaves or matted weeds, seldom requiring to crawl up a stalk or stem, while on the short turf of the downs and pas- tures the smaller and more rounded shell enables the animal to manoeuvre in and out of the blades of grass, and even to crawl up them with considerable activity. The same writer endeay- ours to explain the causes which regulate the distribution of H. caperata var. ornata. He found that this variety (dark bands on a white ground) occurred almost exclusively on downs which were fed upon by sheep, associated with the common or mottled form, while the latter form alone occurred in localities where sheep were not accustomed to feed. Assuming then, as is prob- ably the case, that sheep, in the course of their close pasturing, devour many small snails, he believes that individuals of the more conspicuous form ornata were more likely to be noticed, and therefore avoided, by the sheep, than the mottled form, which would more easily escape their observation. Hence the var. ornata is due to the advantage which strikingly coloured individuals obtained owing to their conspicuous habit, as com- pared with the typical form, which would be less readily de- tected. (6) Changes in Soil, Station, Character of Water, ete.—A deficiency of lime in the composition of the soil of any particular locality produces very marked effects upon the shells of the Mollusca which inhabit it; they become small and very thin, occasionally almost transparent. The well-known var. tenuis of Helix aspersa occurs on downs in the Channel Islands where calcareous material is scarce. For similar reasons, H. arbusto- rum develops a var. fusca, which is depressed, very thin, and transparent, at Scilly, and also at Lunna I., E. Zetland. The common dog-whelk (Purpura lapillus) of our own coasts 1 Journ. of Conch. vi. p. 123. Fic. 35.— 19 specimens of Purpura lapillus L., Great Britain, illustrating variation. (1) Felixstowe, sheltered coast; (2), (8) Newquay, on veined and coloured rock; (4) Herm, rather exposed; (5) Solent, very sheltered; (6) Land’s End, exposed rocks, small food supply ; (7) Scilly, exposed rocks, fair food supply ; (8) St. Leonards, flat mussel beds at extreme low water ; (9) Robin Hood’s Bay, sheltered under boulders, good food supply ; (10) Rhoscollyn, on oyster bed, 4-7 fath. (Macandrew); (11) Guernsey, rather exposed rocks ; (12) Estuary of Conway, very shel- tered, abundant food supply ; (18), (14) Robin Hood’s Bay, very exposed rocks, poor food supply; (14) slightly monstrous ; (15), (16), (17) Morthoe, rather exposed rocks, but abundant food supply ; (18) St. Bride’s Bay ; (19) L. Swilly, sheltered, but small food supply. All from the author’s collee- tion, except (10). CHAP. III VARIATION OF PURPURA LAPILLUS gI is an exceedingly variable species, and in many cases the varia- tions may be shown to bear a direct relation to the manner of life (Fig. 85). Forms occurring in very exposed situations, e.g. Land’s End, outer rocks of the Scilly Is., coasts of N. Devon and Yorkshire, are stunted, with a short spire and relatively large mouth, the latter being developed in order to increase the power of adherence to the rock and consequently of resistance to wave force. On the other hand, shells occurring in sheltered situations, estuaries, narrow straits, or even on open coasts where there is plenty of shelter from the waves, are comparatively of great size, with a well-developed, sometimes produced spire, and a mouth small in proportion to the area of shell surface. In the accompanying figure, the specimens from the Conway estuary and the Solent (12, 5) well illustrate this latter form of shell, while that from exposed rocks is illustrated by the specimens from Robin Hood’s Bay (18, 14). Had these specimens occurred alone, or had they been brought from some distant and unexplored region, they must inevitably have been described as two distinct species. Mr. W. Bateson has made! some observations on the shells of Cardiwm edule taken from a series of terraces on the border Fic. 36.— Valves of Curdium edule from the four upper terraces of Shumish Kul, a dry salt lake adjacent to the Aral Sea. (After Bateson.) of certain salt lakes which once formed a portion of the Sea of Aral. As these lakes gradually became dry, the water they contained became salter, and thus the successive layers of dead shells deposited on their borders form an interesting record of the progressive variation of this species under conditions which, in one respect at least, can be clearly appreciated. At the same time the diminishing volume of water, and the increasing average temperature, would not be without their effect. It was 1 Phil. Trans. 1889, vol. 180 B, p. 297. A somewhat similar case (the cele- brated Steinheim series of Planorbis) is dealt with by Hilgendorf, WB. Akad. Berl. 1866, p. 474; and Hyatt, Proc. Amer. Ass. Sc. xxix. p. 527. Q2 VARIATION IN UNIO AND ANODONTA CHAP. found that the principal changes were as follows: the thickness, and consequently the weight, of the shells became diminished, the size of the beaks was reduced, the shell became highly coloured, and diminished considerably in size, and the breadth of the shells increased in proportion to their length (Fig. 36). Shells of the same species of Cardium, occurring in Lake Mare- otis, were found to exhibit very similar variations as regards colour, size, shape, and thickness. Unio pictorum var. compressa occurs near Norwich at two similar localities six or seven miles distant from one another, under circumstances which tend to show that similar conditions have produced similar results. The form occurs where the river, by bending sharply in horse-shoe shape, causes the current to rush across to the opposite side and form an eddy near the bank on the outside of the bend. Just at the edge of the sharp cur- rent next the eddy the shells are found, the peculiar form being probably due to the current continually washing away the soit particles of mud and compelling the shell to clongem itself in order to keep partly buried at the bottom. The rivers Ouse and Foss, which unite just below York, are rivers of strikingly different character, the Ouse being deep, rapid, with a bare, stony bottom, and little vegetable growth, and receiving a good deal of drainage, while the Foss is shallow, slow, muddy, full of weeds and with very little drainage. In the Foss, fine specimens of Anodonta anatina occur, lustrous, with beautifully rayed shells. A few yards off, in the Ouse, the same species of Anodonta is dull brown in colour, its interior clouded, the beaks and epidermis often deeply eroded. Precisely the same contrast is shown in specimens of Unio twmidus, taken from the same rivers, Ouse specimens being also shghtly curved inform. Just above Yearsley Lock in the Foss, Unio tumidus occurs, but always dwarfed and malformed, a result probably due to the effect of rapidly running water upon a species accus- tomed to live in still water.2. Simroth records the occurrence of remarkably distorted varieties in two species of Aetheria which lived in swift falls of the River Congo.’ A variety of Limnaea peregra with a short spire and rather strong, stoutly built shell occurs in Lakes Windermere, Derwent- 1 J. B. Bridgman, Quart. Journ. Coneh. i. p. 70. 2 W.C. Hey, Journ. of Conch. iii. p. 268. 3 Zool. Anz. xiii. p. 662. III VARIATION IN LITTORINA 93 water, and Llyn-y-van-fach. It lives adhering to stones in places where there are very few weeds, its shape enabling it to withstand the surf of these large lakes, to which the ordinary form would probably succumb.! Scalariform specimens of Planorbis are said to occur most commonly in waters which are choked by vegetation, and it has been shown that this form of shell is able to make its way through masses of dense weed much more readily than speci- mens of normal shape. Continental authorities have long considered Limnaea peregra and L. ovata as two distinct species. Hazay, however, has suc- , ceeded in rearing specimens of so-called peregra from the ova of ovata, and so-called ovata from the ova of peregra, simply by placing one species in running water, and the other in still water. According to Mr. J. S. Gibbons? certain species of Littorina, in tropical and subtropical regions, are confined to water more or less brackish, being incapable of living in pure salt water. “T have met,” says Mr. Gibbons, “with three of these species, and in each case they have been distinguished from the truly marine species by the extreme (comparative) thinness of their shells, and by their colouring being richer and more varied; they are also usually more elaborately marked. They are to be met with under three different conditions — (1) in harbours and bays where the water is salt with but a slight admixture of fresh water; (2) in mangrove swamps where salt and fresh water mix in pretty equal volume; (8) on dry land, but near a marsh or the dry bed of one. “TL. intermedia Reeve, a widely diffused E. African shell, attaches itself by a thin pellicle of dried mucus to grass growing by the margin of slightly brackish marshes near the coast, re- sembling in its mode of suspension the Old World Cyelostoma. I have found it in vast numbers in situations where, during the greater part of the year, it is exposed to the full glare of an almost vertical sun, its only source of moisture being a slight dew at night-time. The W. Indian L. angulifera Lam., and a beautifully coloured E. African species (? L. carinifera), are found in mangrove swamps; they are, however, less independent of salt water than the last.” 1 J. Madison, Journ. of Conch. v. p. 260. 2 Quart. Journ. Conch. i. 3389. O04. EFFECT OF VOLUME OF WATER CHAP. Mr. Gibbons goes on to note that brackish water species (although not so solid as truly marine species) tend to become more solid as the water they inhabit becomes less salt. This is a curious fact, and the reverse of what one would expect. Specimens of L. intermedia on stakes at the mouth of the Lorengo Marques River, Delagoa Bay, are much smaller, darker, and more fragile, than those living on grass a few hundred yards away. L. angulifera is unusually solid and heavy at Puerto Plata (S. Domingo) among mangroves, where the water is in a great measure fresh; at Havana and at Colon, where it lives on stakes in water but slightly brackish, it is thinner and smaller and also darker coloured. (c) Changes in the Volume of Water.—It has long been known that the largest specimens, e.g. of Limnaea stagnalis and Anodonta anatina, only occurred in pieces of water of consider- able size. Recent observation, however, has shown conclusively that the volume of water in which certain species live has a very close relation to the actual size of their shells, besides producing other effects. Limnaea megasoma, when kept in an aquarium of limited size, deposited eggs which hatched out; this process was continued in the same aquarium for four generations in all, the form of the shell of the last generation having become such that an experienced conchologist gave it as his opinion that the first and last terms of the series could have no possible specific relation to one another. ‘The size of the shell became greatly diminished, and in particular the spire became very slender. The same species being again kept in an aquarium under similar conditions, it was found that the third generation had a shell only four-sevenths the length of their great grandparents. It was noticed also that the sexual capacities of the animals changed as well. The liver was greatly reduced, and the male organs were entirely lost.? K. Semper conducted some well-known experiments bearing on this point. He separated ® specimens of Limnaea stagnalis from the same mass of eggs as soon as they were hatched, and placed them simultaneously in bodies of water varying in vol- ume from 100 to 2000 cubic centimetres. All the other condi- tions of life, and especially the food supply, were kept at the 1 Whitfield, Bull. Amer. Mus. N. H. i. p. 29. 2 Amer. Nat. xiv. p. 51. 3 Animal Life, Ed. 1, p. 160 f. Ill EFFECT OF VOLUME OF WATER 95 known optimum. He found, in the result, that the size of the shell varied directly in proportion to the volume of the water in which it lived, and that this was the case, whether an individual specimen was kept alone in a given quantity of water, or shared it with several others. At the close of 65 days the specimens raised in 100 cubic cm. of water were only 6 mm. long, those in 250 cubic cm. were 9 mm. long, those in 600 cubic cm. were 12 mm. long, while those kept in 2000 cubic cm. attained a length of 18 mm. (F ig 5 37). Fig. 37.— Four equally old An interesting effect of a sudden fall shells of Limnaea stag- of temperature was noticed by Semper in een its ores an same mass of ova, but connection with the above experiments. reared in different vol- Vessels of unequal size, containing speci- Feo hs ean eat mens of the Zimnaea, happened to stand in 2000 cubic centime- before a window at a time when the tem- ‘"* “*te* Semper) perature suddenly fell to about 55° F. The sun, which shone through the window, warmed the water in the smaller vessels, but had no effect upon the temperature of the larger. The result was, that the Limnaea in 2000 cubic cm., which ought to have been 10 mm. long when 25 days old, were scarcely longer, at the end of that period, than those which had lived in the smaller vessels, but whose water had been sufficiently warm. CHAPTER IV USES OF SHELLS FOR MONEY, ORNAMENT, AND FOOD — CULTI- VATION OF THE OYSTER, MUSSEL, AND SNAIL—SNAILS AS MEDICINE — PRICES GIVEN FOR SHELLS THE employment of shells as a medium of exchange was exceedingly common amongst uncivilised tribes in all parts of the world, and has by no means yet become obsolete. One of the commonest species thus employed is the ‘money cowry’ (Cypraea moneta, L.), which stands almost alone in being used entire, while nearly all the other forms of shell money are made_ out of portions of shells, thus requiring a certain amount of labour in the process of formation. One of the earliest mentions of the cowry as money occurs in an ancient Hindoo treatise on mathematics, written in the seventh century A.D. A question is propounded thus: ‘the + of _ qi of 4 of 2 of 3 of 3a dramma was given to a beggar by one from whom he asked an alms; tell me how many cowry shells the miser gave.’ In British India about 4000 are said to have passed for a shilling, but the value appears to differ according to their condition, poor specimens being comparatively worth- less. According to Reeve! a gentleman residing at Cuttack is said to have paid for the erection of his bungalow entirely in cowries. The building cost him 4000 Rs. sicca (about £400), and as 64 cowries=1 pice, and 64 pice=1 rupee sicea, he paid over 16,000,000 cowries in all. Cowries are imported to England from India and other places for the purposes of exportation to West Africa, to be exchanged for native products. ‘The trade, however, appears to be greatly on the decrease. At the port of Lagos, in 1870, 50,000 ewts. of cowries were imported.” 1 Conch. Syst. ii. p. 262 n. 2p. L. Simmonds, Commercial Products of the Sea, p. 278. 96 CHAP. IV SHELLS AS MONEY — WAMPUM 97 A banded form of Nerita polita was used as money in certain parts of the South Pacific. The sandal-wood imported into the China market is largely obtained from the New Hebrides, being purchased of the natives in exchange for Ovulum angulosum, which they especially esteem as an ornament. Sometimes, as in the Duke of York group, the use of shell money is specially restricted to certain kinds of purchase, being employed there only in the buying of swine. Among the tribes of the North-West coasts of America the common Dentalium indianorum used to form the standard of value, until it was superseded, under the auspices of the Hud- son’s Bay Company, by blankets. A slave was valued at a fathom of from 25 to 40 of these shells, strung lengthwise. Inferior or broken specimens were strung together in a similar way, but were less highly esteemed; they corresponded more to our silver and copper coins, while the strings of the best shells represented gold. The wampum of the eastern coast of North America differed | from all these forms of shell money, in that it required a labori- ous process for its manufacture. Wampum consisted of strings. of cylindrical beads, each about a quarter of an inch in length and half that breadth. The beads were of two colours, white and purple, the latter being the more valuable. Both were | formed from the common clam, Venus mercenaria, the valves of which are often stained with purple at the lower margins, while the rest of the shell is white. Cut small, ground down, and pierced, these shells were converted into money, which appears to have been current along the whole seaboard of North America from Maine to Florida, and on the Gulf Coast as far as Central America, as well as among the iniand tribes east of the Missis-_ sippi. Another kind of wampum was made from the shells of Busycon carica and B. perversum. By staining the wampum with various colours, and disposing these colours in belts in various forms of arrangement, the Indians were able to preserve records, send messages, and keep account of any kind of event, treaty, or transaction. Another common form of money in California was Olivella » biplicata, strung together by rubbing down the apex. , Button- shaped disks cut from‘ Sazidomus arata and Pachydesma crassa- tellordes, as well as oblong pieces of Haliotis, were employed for VOL. III H i 98 SHELLS AS ORNAMENTS CHAP. the same purpose, when strung together in lengths of several yards. : ‘“ There is a curious old custom,” writes Mr. W. Anderson Smith,! “that used formerly to be in use in this locality [the western coast of Scotland], and no doubt was generally em- ployed along the seaboard, as the most simple and ready means of arrangement of bargains by a non-writing population. That was, when a bargain was made, each party to the transaction got one half of a bivalve shell — such as mussel, cockle, or oyster — and when the bargain was implemented, the half that fitted exactly was delivered up as a receipt! Thus a man who had a box full of unfitted shells might be either a creditor or a debtor ; but the box filled with fitted shells represented receipted ac- counts. Those who know the difficulty of fitting the valves of some classes of bivalves will readily acknowledge the value of this arrangement.” Shells are employed for use and for ornament by savage — and even by civilised — tribes in all parts of the world. J The. natives of Fiji thread the large Turbo argyrostoma and crenulatus .as weights at the edge of their nets, and also employ them as’ sinkers. A Cypraea tigris cut into two halves and placed round a stone, with two or three showy Oliva at the sides, is used as a bait for cuttles. Avicula margaritifera is cut into scrapers and knives by this and several other tribes. Breast ornaments of ‘ Chama, grouped with Solarium perspectivum and Terebra dupli- cata are common among the Fijians, who also mount the Avicula / on a backing of whales’ teeth sawn in two, for the same purpose. “ The great Orange Cowry (Cypraea aurantiaca) is used as a badge of high rank among the chieftains. One of the most remarkable Fijian industries is the working of whales’ teeth to represent this cowry, as well as the commoner C’. talpa, which is more easily imitated. Among the Solomon islanders, cowries are used to ornament their shields on great field days, and split cowries are worn as a necklace, to represent human teeth. Small bunches of Fere- bellum subulatwm are worn as earrings, and a large valve of Avicula is employed as a head ornament in the centre of a fillet. The same islanders ornament the raised prows of their canoes, as well as the inside of the stern-post, with a long row of single Natica. 1 Benderloch, p. 118. Vv SHELLS AS ORNAMENTS 99 The native Papuans employ shells for an immense variety’ of purposes. Circlets for the head are formed of rows of Nassa » gibbosula, rubbed down till little but the mouth remains. Neck- laces are worn which consist of strings of Oliva, young Avicula, Natica melanostoma, opercula of Turbo, and valves of a rich brown species of Cardium, pendent at the end of strings of the seeds known as Job’s tears. Struthiolaria is rubbed down until nothing but the mouth is left, and worn in strings round the neck. This is remarkable, since Struthiolaria is not a native Papuan shell, and indeed occurs no nearer than New Zealand. Sections of Melo are also worn as a breast ornament, dependent from a necklace of cornelian stones. Cypraea erosa is used to ornament drinking bowls, and Ovulum ovum is attached to the native drums, at the base of a bunch of cas- sowary feathers, as well as being fastened to the handle of a sago-beater. In the same island, the great Furbo and Conus millepunctatus are ground down to form bracelets, which are worn on the biceps. The crimson lip of Strombus luhuanus is cut into beads “ and perforated for necklaces. Village elders are distinguished _ by a single Ovulum verrucosum, worn in the centre of the fore- — head. The thick lip of Cassis cornuta is ground down to form * nose pieces, 44 inches long. Fragments of a shell called Kaima (probably valves of a large Spondylus) are worn suspended from the ears, with little wisps of hair twisted up and thrust through a hole in the centre. For trumpets, Cassis cornuta, Triton tritonis, and Ranella lampas are used, with a hole drilled as a mouthpiece in one of the upper whorls. Valves of Batissa, ’ Unio, and Mytilus are used as knives for peeling yams. Spoons for scooping the white from the cocoa-nut are made from Avicula margaritifera. Melo diadema is used as a baler in the * canoes.} In the Sandwich Islands Melampus luteus is worn as a necklace, as well as in the Navigator Islands. A very striking necklace, in the latter group, is formed of the apices of a Nautilus, rubbed down to show the nacre. The New Zealanders use the green opercula of a Turbo, a small species of Venus,and | Cypraea asellus to form the eyes of their idols. Fish-hooks + are made throughout the Pacific of the shells of Avicula and , 1C, Hedley in J. P. Thomson, Brit. New Guinea, p. 283. 100 SHELLS AS ORNAMENTS—AS SYMBOLS OF WORSHIP cnap. | Haliotis, and are sometimes strengthened by a backing made of the columella of Cypraea arabica. Small axe-heads are made from Terebra crenulata ground down (Woodlark I.), and larger « forms are fashioned from the giant 7ridacna (Fiji). Shells are used to ornament the elaborate cloaks worn by the women of rank in the Indian tribes of South America. Speci- mens of Ampullaria, Orthalicus, Labyrinthus, and Bulimulus depend from the bottom and back of these garments, while great Bulimi, 6 inches long, are worn as a breast ornament, and at the end of a string of beads and teeth.! The chank-shell (Zurbinella rapa) is of especial interest from its connexion with the religion of the Hindoos.- The god Vishnu is represented as holding this shell in his hand, and the sinistral form of it, which is excessively rare, is regarded with extraordinary veneration. ‘The chank appears as a symbol on the coins of some of the ancient Indian Empires, and is still retained on the coinage of the Rajah of Travancore. The chief fishery of the chank-shell is at Tuticorin, on the Gulf of Manaar, and is conducted during the N. E. monsoon, October-May. In 1885-86 as many as 332,000 specimens were obtained, the net amount realised being nearly Rs.24,000. In former days the trade was much more lucrative, 4 or 5 millions of specimens being frequently shipped. The government of Ceylon used to receive £4000 a year for licenses to fish, but now the trade is free. The shells are brought up by divers from 2 or 8 fathoms of water. In 1887 a sinistral specimen was found at Jaffna, which sold for Rs.700.2 Nearly all the shells are sent to Dacca, where they are sliced into bangles and anklets to be worn by the Hindoo women. Perhaps the most important industry which deals only with the shells of Mollusca is that connected with the ‘ pearl-oyster.’ The history of the trade forms a small literature in itself. It must be sufficient here to note that the species in question is not an ‘ oyster,’ properly so called, but an Avicula (margaritifera Lam.). The ‘mother-of-pearl,’ which is extensively employed for the manufacture of buttons, studs, knife-handles, fans, card- cases, brooches, boxes, and every kind of inlaid work, is the 1 Most of the above facts are derived from a study of a collection of native implements, weapons, ornaments, etc., inthe Antiquarian Museum at Cambridge. 2 Thurston, Notes on the Pearl and Chank Fisheries, Madras, 1890. »y IV PEARL FISHERIES IOI internal nacreous laminae of the shell of this species. The most important fisheries are those of the Aru Islands, the Soo-loo Archipelago, the Persian Gulf, the Red Sea, Queensland, and the Pearl Islands in the Bay of Panama. The shell also occurs in several of the groups of the South Pacific —the Paumotu, Gambier and Navigator Islands, Tahiti being the centre of the trade — and also on the coasts of Lower California.! Pearls are the result of a disease in the animal of this species of Avicula and probably in all other species within which they occur. When the Avicula is large, well formed, and with ample space for individual development, pearls scarcely occur at all, but when the shells are crowded together, and become humped and distorted, as well as affording cover for all kinds of marine worms and parasitic creatures, then pearls are sure to be found. Pearls of inferior value and size are also produced by Placuna placenta, many species of Pinna, the great Tridacna, the common Ostrea edulis, and several other marine bivalves. They are not uncommon in Unio and Anodonta, and the common Margaritana margaritifera of our rapid streams is still said to be collected, in some parts of Wales, for the purpose of ex- tracting its small ‘ seed-pearls.’ Pink pearls are obtained from the giant conch-shell of the West Indies (Strombus gigas), as well as from certain Turbinella. In Canton, many houses are illuminated almost entirely by skylights and windows made of shells, probably the semi- transparent valves of Placuna placenta. .In China lime is commonly made of ground cockle-shells, and, when mixed with oil, forms an excellent putty, used for cementing coffins, and in forming a surface for the frescoes with which the gables of temples and private houses are adorned. Those who suffer from cutaneous diseases, and convalescents from small-pox, are washed in Canton with the water in which cockles have been boiled.? A recent issue of the Peking Gazette contains a report from the outgoing Viceroy of Fukhien, stating that he had handed over the insignia of office to his successor, including enter alia the conch-shell bestowed by the Throne. A conch-shell with a whorl turning to the right, 7.e. a sinistral specimen, is supposed when blown to have the effect of stilling the waves, and hence is 1 See in particular, P. L. Simmonds, The Commercial Products of the Sea. 2H. Friend, Field Club, iv. 1893, p. 100. 102 VARIOUS USES OF SHELLS CHAP. bestowed by the Emperor upon high officers whose duties oblige them to take voyages by sea. The Viceroy of Fukhien probably possesses one of these shells in virtue of his jurisdiction over Formosa, to which island periodical visits are supposed to be made.1 Shells appear to be used occasionally by other species besides man. Oyster-catchers at breeding time prepare a number of imitation nests in the gravel on the spit of land where they build, putting bits of white shell in them to represent eggs.* This looks like a trick in order to conceal the position of the true nest. According to Nordenskjold, when the eider duck of Spitzbergen has only one or two eggs in its nest, it places a shell of Buecinum glaciale beside them. ‘The appropriation of old shells by hermit-crabs is a familiar sight all over the world. Perhaps it is most striking in the tropics, where it is really startling, at first experience, to meet —as I have done —a large Cassis or Turbo, walking about in a wood or on a hill side at considerable distances from the sea. A Gephyrean (Phascolion strombi) habitually establishes itself in the discarded shells of marine Mollusca. Certain Hymenoptera make use of dead shells of Helix hortensis in which they build their cells.2 Magnus believes that in times when heavy rains prevail, and the usual insects do not venture out, certain flowers are fertilised by snails and slugs crawling over them, e.g. Leucanthemum vulgare by Limasx laevis.* Mollusca as Food for Man. — Probably there are few coun- tries in the world in which less use is made of the Mollusca as a form of food than in our own. There are scarcely ten native species which can be said to be at all commonly employed for this purpose. Neighbouring countries show us an example in this respect. The French, Italians, and Spanish eat Watica, Turbo, Triton, and Murex, and, among bivalves, Donax, Venus, Litho- domus, Pholas, Tapes, and Cardita, as well as the smaller Cephalopoda. Under the general designation of clam the Ameri- cans eat Venus mercenaria, Mya arenaria, and Mactra solidissima. In the Suez markets are exposed for sale Strombus and Melon- gena, Avicula and Cytherea. At Panama Donaz and Solen are 1 Nature, xxxi. 1885, p. 492. 2 W. Anderson Smith, Benderloch, p. 173. 3 Dominique, Fewill. Nat. xviii. p. 22. 4 SB. Nat. Fr. Berl. 1889, p. 197. IV MOLLUSCA AS FOOD FOR MAN 103 delicacies, while the natives also eat the great Murex and Pyrula, and even the huge Arca grandis, which lives embedded in the liquid river mud. The common littoral bivalves seem to be eaten in nearly all countries except our own, and it is therefore needless to enu- merate them. The Gasteropoda, whose habits are scarcely so cleanly, seem to require a bolder spirit and less delicate palate to venture on their consumption. The Malays of the East Indian islands eat Telescopium Juscum and Pyrazus palustris, which abound in the mangrove swamps. They throw them on their wood fires, and when they are sufficiently cooked, break off the top of the spire and suck the animal out through the opening. Haliotis they take out of the shell, string together, and dry in the sun. The lower classes in the Philippines eat Arca inaequivalvis, boiling them as we do mussels.!_ In the Corean islands a species of Monodonta and another of Mytilus are quite peppery, and bite the tongue; our own Helix revelata, as I can vouch from personal experience, has a similar flavour. Fusus colosseus, Rapana bezoar, and Purpura luteostoma are eaten on the southern coasts of China; Strombus luhuanus, Turbo chrysostomus, Trochus niloticus, and Patella testudinaria, by the natives of New Caledonia; Strombus gigas and Livona pica in the West Indies; Turbo niger and Concholepas ‘peruvianus on the Chilian coasts; four species of Strombus and Nerita, one each of Purpura and Turbo, besides two Tridacna and one Hippopus, by the natives of British New Guinea. West Indian negroes eat the large Chitons which are abundant on their rocky coasts, cutting off and swallowing raw the fleshy foot, which they call ‘beef,’ and rejecting the viscera. Dried cephalopods are a favourite Chinese dish, and are regularly ex- ported to San Francisco, where the Chinamen make them into soup. The ‘Challenger’ obtained two species of Sepia and two of Loligo from the market at Yokohama. The insipidity of fresh-water Moliusca renders them much less desirable as a form of food. Some species of Unionidae, however, are said to be eaten in France. Anodonta edulis is specially cultivated for food in certain districts of China, and the African Aetheriae are eaten by negroes.. Navicella and Neritina are eaten in Mauritius, Ampullaria and Neritina in Guadeloupe, and Paludina in Cambodia. 1A, Adams, Voyage of the ‘ Samarang,’ ii. p. 308. 104 OYSTERS UNDER THE ROMANS CHAP. The vast heaps of empty shells known as ‘ kitchen-middens,’ occur in almost every part of the world. They are found in Scotland, Denmark, the east and west coasts of North America, Brazil, Tierra del Fuego, Australia and New Zealand, and are sometimes several hundred yards in length. They are invariably composed of the edible shells of the adjacent coast, mixed with bones of Mammals, birds, and fish. From their great size, it is believed that many of them must have taken centuries to form. Pre-eminent among existing shell-fish industries stands the cultivation of the oyster and the mussel, a more detailed account of which may prove interesting. The cultivation of the oyster! as a luxury of food dates at least from the gastronomic age of Rome. Every one has heard of the epicure whose taste was so educated that “he could tell At the first mouthful, if his oysters fed On the Rutupian or the Lucrine bed Or at Circeii.” 2 The first artificial oyster-cultivator on a large scale appears to have been a certain Roman named Sergius Orata, who lived about a century B.c. His object, according to Pliny the elder,? was not to please his own appetite so much as to make money by ministering to the appetites of others. His vevaria were situ- ated on the Lucrine Lake, near Baiae, and the Lucrine oysters obtained under his cultivation a notoriety which they never entirely lost, although British oysters eventually came to be more highly esteemed. He must have been a great enthusiast in his trade, for on one occasion when he became involved in a law-suit with one of the riparian proprietors, his counsel declared that Orata’s opponent made a great mistake if he expected to damp his ardour by expelling him from the lake, for, sooner than not grow oysters at all, he would grow them upon the roof of his house. Orata’s successors in the business seem to have understood the secret of planting young oysters in new beds, for 1 Much information has been derived, on this subject, from Bertram’s Har- vest of the Sea, Simmonds’ Commercial Products of the Sea, the publications of the Fisheries Exhibition, especially vol. xi. (Anson and Willett) ; see also Phil- pots, Oysters and all about them. 2 Juvenal, Sat. iv. 140-142. 8 Hist. Nat. ix. 79. 4 Val. Max. ix. 1. IV OYSTERS UNDER THE ROMANS 105 we are told that specimens brought from Brundisium and even from Britain were placed for a while in the Lucrine Lake, to fatten after their long journey, and also to acquire the esteemed * Lucrine flavour.” Oysters are ‘in season’ whenever there is an ‘r’ in the month, in other words, from September to April. ‘Mensibus erratis,’ as the poet has it, ‘vos ostrea manducatis!’ It has been com- puted that the quantity annually produced in Great Britain amounts to no less than sixteen hundred million, while in America the number is estimated at five thousand five hundred million, the value being over thirteen million dollars, and the number of persons employed fifty thousand. Arcachon, one of the principal French oyster-parks, has nearly 10,000 acres of oyster beds, the annual value being from eight to ten million franes; in 1884-85, 178,359,000 oysters were exported from this place alone. In the season 1889-90, 50,000 tons of oysters were consumed in London. Few will now be found to echo the poet Gay’s opinion : “That man had sure a palate covered o’er With brass or steel, that on the rocky shore First broke the oozy oyster’s pearly coat, And risq’d the living morsel down his throat.” There were halcyon days in England once, when oysters . were to be procured at 8d. the bushel. Now it costs exactly that amount before a bushel, brought up the Thames, can even be exposed for sale at Billingsgate (4d. porterage, 4d. market toll), and prime Whitstable natives average from 34d. to 4d. each. The principal causes of this rise in prices, apart from the increased demand, are (1) over-dredging, (2) ignorant cultiva- tion, and to these may be added (3) the effect of bad seasons in destroying young oysters, or preventing the spat from maturing. Our own principal beds are those at Whitstable, Rochester, Colchester, Milton (famous for its ‘melting’ natives), Faver- sham, Queenborough, Burnham, Poole, and Carlingford in Co. Down, and Newhaven, near Edinburgh. The oyster-farms at Whitstable, public and private, extend over an area of more than 27 square miles. The principal of these is a kind of joint-stock company, with no other privilege of entrance except birth as a free dredgeman of the town. When a holder dies, his interest dies with him. Twelve directors, 106 CULTIVATION OF THE OYSIER IN BRITISH ISLANDS cuap. known as “the Jury,” manage the affairs of the company, which finds employment for several thousand people, and sometimes turns over as much as £200,000 a year. The term ‘ Natives,’ as applied to these Whitstable or to other English oysters, requires a word of explanation. A ‘Native’ oyster is simply an oyster which has been bred on or near the Thames estuary, but very probably it may be developed from a brood which came from Scotland or some other place at a distance. For some unex- plained reason, oysters bred on the London clay acquire a greater delicacy of flavour than elsewhere. The company pay large sums for brood to stock their own grounds, since there can be ~ no certainty that the spat from their own oysters will fall favour- ably, or even within their own domains at all. Besides pur- chases from other beds, the parks are largely stocked with small oysters picked up along the coast or dredged from grounds public to all, sometimes as much as 50s. a bushel being paid for the best brood. It is probably this system of transplanting, combined with systematic working of the beds, which has made the Whitstable oyster so excellent both as to quality and quantity of flesh. The whole surface of the ‘layings’ is explored every year by the dredge, successive portions of the ground being gone over in regular rotation, and every provision being made for the well-being of the crop, and the destruction of their enemies. For three days of every week the men dredge for ‘ planting,’ z.e. for the transference of suitable specimens from one place to another, the separation of adhering shells, the removal of odd valves and of every kind of refuse, and the killing off of dangerous foes. On the other three days they dredge for the market, taking care only to hft such a number as will match the demand. The Colne beds are natural beds, as opposed to the majority of the great working beds, which are artificial. They are the property of the town of Colchester, which appoints a water- bailiff to manage the concern. Under his direction is a jury of twelve, who regulate the times of dredging, the price at which sales are to be made, and are generally responsible for the practical working of the trade. Here, and at Faversham, Queenborough, Rochester, and other places, ‘natives’ are grown which rival those of Whitstable. There can be no question, however, that the cultivation of oysters by the French is far more complete and efficient than IV CULTIVATION OF THE OYSTER IN FRANCE 107 our own, and has reached a higher degree of scientific perfection combined with economy and solid profits. And yet, between 40 and 50 years ago, the French beds were utterly exhausted and unproductive, and showed every sign of failure and decay. It was in 1858 that the celebrated beds on the Ile de Ré, near Rochelle, were first started. Their originator was a certain shrewd stone-mason, by name Boeuf. He determined to try, entirely on his own account, whether oysters could not be made to grow on the long muddy fore-shore which is left by the ebb of the tide. Accordingly, he constructed with his own hands a small basin enclosed by a low wall, and placed at the bottom a number of stones picked out of the surrounding mud, stocking his ‘pare’ with a few bushels of healthy young brood. The experiment was entirely successful, in spite of the jeers of his neighbours, and Boeuf’s profits, which soon began to mount up at an astonishing rate, induced others to start similar or more extensive farms for themselves. The movement spread rapidly, and in a few years a stretch of miles of unproductive mud banks was converted into the seat of a most prosperous industry. The general interests of the trade appear to be regulated in a similar manner to that at Whitstable; delegates are appointed by the various communities to watch over the business as a whole, while questions affecting the well-being of oyster-culture are discussed in a sort of representative assembly. At the same time as Boeuf was planting his first oysters on the shores of the Ile de Ré, M. Coste had been reporting to the French government in favour of such a system of ostreiculture as was then practised by the Italians in the old classic Lakes Avernus and Lucrinus. The principle there adopted was to prevent, as far as possible, the escape of the spat from the ground at the time when it is first emitted by the breeding oyster. Stakes and fascines of wood were placed in such a position as to catch the spat and give it a chance of obtaining a hold before it perished or was carried away into the open sea. The old oyster beds in the Bay of St. Brieuc were renewed on this principle, banks being constructed and overlaid with bundles of wood to prevent the escape of the new spat. The attempt was entirely successful, and led to the establishment or re- establishment of those numerous parcs, with which the French coast is studded from Brest to the Gironde. The principal 108 GREEN OYSTERS CHAP. centres of the industry are Arcachon, Auray, Cancale, and la Teste. | It is at Marennes, in Normandy, that the production of the celebrated ‘green oyster’ is carried out, that especial luxury of the French epicure. Green oysters are a peculiarly French taste, and, though they sometimes occur on the Essex marshes, there is no market for them in England. The preference for them, on the continent, may be traced back as early as 1718, when we find a record of their having been served up at a supper given by an ambassador at the Hague. Green oysters are not always green, it is only after they are placed in the ‘claires,’ or fattening ponds, that they acquire the hue; they never occur in the opensea. The green colour does not extend over the whole animal, but is found only in the branchiae and labial tentacles, which are of a deep blue-green. Various theories have been started to explain the ‘ greening’ of the mollusc; the presence of copper in the tanks, the chlorophyll of marine algae, an overgrowth of some parasite, a disease akin to liver complaint, have all found their advocates. Prof. Lankester seems to have established ! the fact, — which indeed had been observed 70 years before by a M. Gaillon, — that the greening is due to the growth of a certain diatom (Navicula ostrearia) in the water of the tanks. This diatom, which is of a deep blue-green colour, appears from April to June,and in September. The oyster swallows quantities of the Mavicula ; the pigment enters the blood in a condition of chemical modification, which makes it colourless in all the other parts of the body, but when the blood reaches the gills the action of the secretion cells causes the blue tint to be restored. The fact that the colour is rather green than blue in the gills, which are yellowish brown, is due to certain optical conditions. Not till the young white oyster has been steeped for several years in the muddy waters of the ‘claires’ does it acquire the proper tint to qualify it for the Parisian restaurant. The ‘claires’ are each about 100 feet square, surrounded by low broad banks of earth, about 3 feet high and 6 feet thick at the base. Before the oysters are laid down, the gates which admit the tide are carefully opened and shut a great many times, in order to collect a sufficient amount of the Wavicula. When this is done, the beds are formed, and are not again overflowed by 1 Quart. Journ. Micr. Sc. xxvi. p. 71. IV OYSTERS IN AMERICA I0Q the sea, except at very high tides. The oysters are shifted from one ‘claire’ to another, in order to perfect the ‘ greening’ process. About fifty million of these ‘ huitres de Marennes ’ are produced annually, yielding a revenue of 2,500,000 francs. It appears, from the experience of one of the most enthusi- astic of French oyster-growers (Dr. Kemmerer), that oysters grow best in muddy water, and breed best in clear water.. Thus the open sea is the place where the spat should fall and be secured, and, as soon as it is of a suitable size, it should be transferred to the closed tank or reservoir, where it will find the quiet and the food (confervae, infusoria, minute algae) which are so requisite for its proper growth. In muddy ground the animal and phosphorous matter increases, and the flesh becomes fatter and more oily. A sudden change from the clear sea- water to the muddy tank is inadvisable, and thus a series of shiftings through tanks with water of graduated degrees of nourishment is the secret of proper oyster cultivation. The American oyster trade is larger even than the French. The Baltimore oyster beds in the Chesapeake River and its tributaries cover 3000 acres, and produce an annual crop of 25 million bushels, as many as 100,900 bushels being sometimes taken from Chesapeake Bay in a single day. Baltimore is the centre of the tinned oyster trade, while that in raw oysters centres in New York. Most of the beds whose produce is carried to New York are situated in New Jersey, Connecticut, Delaware, or Virginia. The laws of these states do not allow the beds to be owned by any but resident owners, and the New York dealers have consequently to form fictitious partnerships with residents near the various oyster beds, supply them with money to buy the beds and plant the oysters, and then give them a share in the profits. It has been estimated that from the Virginia beds 4,000,000 bushels of oysters are carried every year to Fair Haven in New England, 4,000,000 to New York, 3,000,000 to Providence, and 2,000,000 each to Boston, Phila- delphia, and Baltimore. The American ‘ native’ (0. virginica) is a distinct species from our own, being much larger and longer in proportion to its breadth; it is said to be also much more prolific. According to Milne-Edwards,! in the great oyster parks on 1 See G. H. Lewes, Sea-side Studies, p. 339. 110 OYSTERS IN AMERICA CHAP. the coasts of Calvados, the oysters are educated to keep their shells closed when out of water, and so retain water enough inside to keep their gills moist, and arrive at their destination in good condition. As soon as an oyster is taken out of the sea, it closes its shells, and keeps them closed until the shock of removal has passed away, or perhaps until the desirability of a fresh supply of water suggests itself. The men take advantage of this to exercise the oysters, removing them from the sea for longer and longer periods. In time this has the desired effect; the well-educated molluse learns that it is hopeless to ‘ open’ when out of the water, and so keeps his shell closed and his gills moist, and his general economy in good condition. Oysters have been known to live entirely out of water for a considerable time. Prof. Verrill once noticed! a large cluster of oysters attached to an old boot, hanging outside a fish-shop in Washington. They had been taken out of the water on about 10th December, and on 25th February following some of the largest were still alive. It was noticed that all those which sur- vived had the hinge upward and the ventral edge downward, this being the most favourable position possible for the retention of water within the gill-cavity, since the edge of the mantle would pack against the margins of the shell, and prevent the water from leaking away. Such a succulent creature as the oyster has naturally many enemies. One of the worst of these is the ravenous Starfish, or Five-finger. His omnivorous capacities are well described by a clever writer and shrewd observer of nature: ‘“ Here is one doubled up like a sea-urchin, brilliant of hue, and when spread out quite 16 inches in diameter; where, and oh where, can you obtain a prey? The hoe we carry is thrust out and the mass dragged shorewards, when the rascal disgorges two large dog- whelks he has been in the process of devouring. We feel a comfortable glow of satisfaction to think that this enemy of our oyster-beds is also the enemy of our other enemy, this carnivor- ous borer. Here, quite close alongside, is another, only inferior in size, and we drag him ashore lkewise, to find that the fellow has actually had the courage and audacity to suck the contents out of a large horse-mussel (Modiola), the strong muscle alone remaining undevoured. We proceed along but a short way 1 Bull. U. S. Fish. Comm. v. p. 161. - ENEMIES OF THE OYSTER III when we meet with still another in the curled-up condition in which they gorge themselves, and as we drag it shorewards the shell of a Tapes pullastra drops from the relaxing grasp of the ogre. Slowly the extended stomach returns to its place, and the monster settles back to an uncomfortable after-dinner siesta on an exposed boulder; for the starfish wraps its turned-out stomach around the prey it has secured, in place of attempting to devour the limey covering in which most of its game is protected. Once the mouth of the shell is enclosed in the stomach of the starfish, the creature soon sickens, the hinge- spring relaxes its hold, and the shell opening permits the star- fish to suck out the gelatinous contents, and cast free the calcareous skeleton.” ! According to other observers the starfish seizes the oyster with two of his fingers, while with the other three he files away the edge of the flat or upper valve until the points of contact with the round valve are reduced almost to nothing ; then he can introduce an arm, and the rest is easy work. Others suggest that the starfish suffocates the oyster by applying two of its fingers so closely to the edge of the valves that the oyster is unable to open them; after a while the vital powers relax and the shell gapes. The Rev. J. G. Wood holds? that the starfish pours a secretion from its mouth which “ paralyses the hinge muscle and causes the shell to open.” Sometimes in a single night a whole bed of oysters will be totally destroyed by an invasion of starfish. Another dreaded enemy is the ‘ whelk,’ a term which includes Purpura lapillus, Murex erinaceus, Buc- cinum undatum, and probably also Nassa reticulata. All these species perforate the shell with the end of their redula, and then suck out the contents through the neatly drilled hole. Skate fish are the cause of terrible destruction in the open beds, and a scarcely less dangerous visitant is the octopus. Crabs crush the young shells with their claws, and are said to gather in bands and scratch sand or mud over the larger specimens, which makes them open their shells. Yet another, and perhaps unconscious, foe is found in the common mussel, which takes up room meant for the young oysters, grows over the larger individuals, and harbours all sorts of refuse between and under its closely packed 1 W. Anderson Smith, Loch Creran, p. 228. 2 Longmans’ Magazine, June 1889. 112 BREEDING OF THE OYSTER CHAP. ranks. Cliona, a parasitic sponge, bores in between the layers of the oyster’s shell, pitting them with tiny holes (corresponding to its osewla), and disturbing the inmate, who has constantly to construct new layers of shell from the inside. Weed, annelids, ‘blubber,’ shifting sand or mud, sewage or any poisoning of the water, are seriously harmful to the oyster’s best interests. A very severe winter is often the cause of wholesale destruction in the beds. According to the Daily News of 26th March 1891, the Whitstable oyster companies lost property to the value of £30,000 in the exceptionally cold winter of 1890-91, when, on the coast of Kent, the surface temperature of the sea sank below 32°, and the advancing tide pushed a small ice-floe before it. Two million oysters were laid down in one week of the follow- ing spring, to make up for the loss. During the severe winter of 1892-93 extraordinary efforts were made at Hayling I. to protect the oysters from the frost. Twenty million oysters were placed in ponds for the winter, and a steam-engine was for days employed to keep the ponds thawed and supplied with water, while large coal and coke fires were kept burning at the edge of the ponds.!. On the other hand, the unusually warm and sunny summer of 1893 is said to have resulted in the finest fall of spat known in Whitstable for fifty years.” The reproductive activity of the oyster is supposed to com- mence about the third year. Careful research has shown ® that the sexes in the English oyster are not separate, but that each individual is male as well as female, producing spermatozoa as well as ova in the same gland. Here, however, two divergent views appear. Some authorities hold that the oyster does not fecundate its own eggs, but that this operation is performed by spermatozoa emitted by other specimens. It is believed that, in each individual, the spermatozoa arrive at maturity first, and that the ova are not produced until after the spermatozoa have been emitted; thus the oyster is first male and then female, morphologically hermaphrodite, but physiologically unisexual. Others are of opinion that the oyster does fecundate its own egos, ova being first produced, and. passed into the infrabranchial chamber — the ‘ white-sick ’’ stage — and then, after an interval, 1 St. James’s Gazette, 6th January 18938. 2 Also at Arcachon (W. A. Herdman, Natwre, 1893, p. 269). 8 See especially Hoek, Tijdschr. Ned. Dierk. Vereen, Suppl. Deel, i. 1883. ey FALL OF THE SPAT 113 spermatozoa being formed and fecundating these ova — the ‘black-sick’ stage. In this latter view the oyster is first female and then male, and is, both morphologically and physio- logically, hermaphrodite. The old view, that ‘black-sick’ oysters are the male, and ‘white-sick’ the female, is therefore quite incorrect. The ova, in their earliest stage, consist of minute oval clusters of globules floating in a transparent mucus. They pass from the ovary into the gills and folds of the mantle, and are probably fecundated within the excretory ducts of the ovary, before arriving in the mantle chamber. In this stage the oyster is termed ‘white-sick.’ In about a fortnight, as the course of development proceeds, the fertilised ova become ciliated at one end (the so-called veliger stage, p. 131), and soon pigment appears in various parts of the embryos, giving them a darker colour, which varies from grayish to blue, and thus the white- sick oyster becomes ‘black-sick.. When the black spat emerge, they are still furnished with cilia for their free-swimming life. This is of very short duration, for unless the embryo finds some suitable ground on which to affix itself within forty-eight hours, it perishes. As the spat escapes from the parent oyster, which slightly opens its valves and blows the spat out in jets, it resembles a thick cloud in the water, and is carried about at the mercy of wind and tide. April to August are the usual spawning months, warm weather being apparently an absolute necessity to secure the adhering of the spat. A temperature of 65° to 72° F. seems requisite for their proper deposit. Thus on a fine, warm day, with little wind or tide running, the spat will fall near the parents and be safely secured, while in cold, blustering weather it will certainly be carried off to a distance, and prob- ably be altogether lost. The number of young produced by each individual has been variously estimated at from 300,000 to 60,000,000. Either extreme seems enormous, but it must be remembered that besides climatal dangers, hosts of enemies — other Mollusca, fish, and Crustacea — beset the opening career of the young oyster. As soon as the spat has safely ‘fallen,’ it adheres to some solid object, and loses the cilia which were necessary for its Swimming life. It begins to grow rapidly, increasing from about 4, inch in diameter to about the size of a threepenny VOL. III I TIA FALL OF THE SPAT— POISONOUS OYSTERS CHAP. piece in five or six months, and in a year to one inch in diameter. Roughly speaking, the best guide to an oyster’s age is its size; it is as many years old as it measures inches across. The oyster is at its prime at the age of five; its natural life is supposed to be about ten years. The rings, or ‘shoots’ ona shell are not —as is frequently supposed — marks of annual growth; cases have been noticed where as many as three ‘shoots’ were made during the year. An oyster is furnished, on the protruding edges of the mantle, with pigmented spots which may be termed ‘visual organs,’ though they hardly rise to the capacities and organisation of real ‘eyes. But there is no doubt that they are sufficiently sensi- tive to the action of light to enable the oyster to apprehend the approach of danger, and close his doors accordingly. ‘* How sen- sitive, notes Mr. W. Anderson Smith,! ‘the creatures are to the light above them; the shadow of the iron as it passes overhead is instantaneously noted, and snap! the lips are firmly closed.’ The geographical distribution of Ostrea edulis extends from Tranen, in Norway, close to the Arctic circle, to Gibraltar and certain parts of the Mediterranean, Holland, and N. Germany to Heligoland, and the western shores of Sleswick and Jutland. It occurs in Iceland, but does not enter the Baltic, where attempts to.colonise it have always failed. Some authorities regard the Mediterranean form as a distinct species. The literature of oyster-cookery may be passed over in silence. The curious may care to refer to M.S. Lovell’s Hdible British Mollusks, where no less than thirty-nine different ways of dressing oysters are enumerated. It may, however, be worth while to add a word on the subject of povsonous oysters. Cases have been known where a particular batch of oysters has, for some reason, been fatal to those who have partaken of them. It is possible that this may have been due, in certain instances, to the presence of a superabundance of copper in the oysters, and there is no doubt that the symptoms detailed have often closely resembled those of copper poisoning. Cases of poisoning have occurred at Rochefort through the importation of ‘ green oysters’ from Falmouth. It would no doubt be dangerous ever to eat oysters which had grown on the copper bottom of a ship. But copper is present, in more or less minute quantities, in very 1 Benderloch, p. 136. - IV CULTIVATION OF THE MUSSEL IN FRANCE II5 many Mollusca, and it is more probable that a certain form of slow decomposition in some shell-fish develops an alkaloid poison which is more harmful to some people than to others, just as some people can never digest any kind of shell-fish.1 These alkaloid developments from putrescence are called ptomaines. In confirmation of this view, reference may be made to a case, taken from an Indian Scientific Journal, in which an officer, his wife, and household ate safely of a basket of oysters for three days at almost every meal. The basket then passed out of their hands, not yet exhausted of its contents, and a man who had already eaten of these oysters at the officer’s table was after- wards poisoned by some from the same basketful. The cultivation of the common mussel (Mytilus edulis L.) is not practised in this country, although it is used as food in the natural state of growth all round our coasts. The French appear to be the only nation who go in for extensive mussel farming. ‘The principal of these establishments is at a little town called Esnaudes, not far from La Rochelle, and within sight of the Ile de Ré and its celebrated oyster parks. The secret of the cultivation consists in the employment of ‘bou. chots,’ or tall hurdles, which are planted in the mud of the fore-shore, and upon which the mussel (la moule, as the French eall it) grows. The method is said? to have been invented as long ago as 1235 by a shipwrecked Irishman named Walton. He used to hang a purse net to stakes, in the hope of capturing sea birds. He found, however, that the mussels which attached themselves to his stakes were a much more easily attainable source of food, and he accordingly multiplied his stakes, out of which the present ‘ bowchot’ system has developed. The shore is simply a stretch of liquid mud, and the bouchots are arranged in shape like a single or double V, with the opening looking towards the sea. The fishermen, in visiting the bouchots, glide about over the mud in piroques or light, flat-bottomed boats, propelling them by shoving the mud with their feet. Each bouchot is now about 450 yards long, standing 6 feet out of the mud, making a strong wall of solid basket-work, and as there are altogether at least 500 bouchots, the total mussel-bearing length of wall is nearly 130 miles. 1 This is the view of E, Ray Lankester, Quart. Journ. Micr. Sc. xxvi. 80. 2 De Quatrefages, Rambles of a Naturalist. > 116 ECONOMY OF THE MUSSEL CHAP. The mussel-spat affixes itself naturally to the bouchots nearest the sea, in January and February. Towards May the planting begins. The young mussels are scraped off these outermost bouchots, and placed in small bags made of old canvas or netting, each bag holding a good handful of the mussels. The bags are then fastened to some of the inner bouchots, and the mussels soon attach themselves by their byssus, the bag rotting and falling away. They hang in clus- ters, increasing rapidly in size, and at the proper time are trans- planted to bouchots farther and farther up the tide level, the object being to bring the matured animal as near as possible to the land when it is time for it to be gathered. ‘This process, which aims at keeping the mussel out of the mud, while at the same time giving it all the nutrition that comes from such a habitat, extends over about a year in the case of each individual. Quality, rather than quantity, is the aim of the HEsnaudes boucholiers. The element of quantity, however, seems to come in when we are told that each yard of the bouchots is calculated to yield a cartload of mussels, value 6 francs, and that the whole _ annual revenue is at least £52,000. In this country, and especially in Scotland, mussels are largely used as bait for long-line fishing. Of late years other substances have rather tended to take the place of mussels, but within the last twenty years, at Newhaven on the Firth of Forth, three and a half million mussels were required annually to supply bait for four deep-sea craft and sixteen smaller vessels. According to Ad. Meyer,! boughs of trees are laid down in Kiel Bay, and taken up again, after three, four, or five years, between December and March, when they are found covered with fine mussels. ‘The boughs are then sold, just as they are, by weight, and the shell-fish sent into the interior of Germany. Mussels are very sensitive to cold weather. In 1874, during an easterly gale, 195 acres of mussels at Boston, in Lincoln- shire, were killed in a single night. They soon affix themselves to the bottom of vessels that have lain for any length of time in harbour or near the coast. The bottom of the Great Hastern steamship was at one time so thickly coated with mussels that it was estimated that a vessel of 200 tons could have been laden from her. 1 Quoted by Jeffreys, Brit. Conch. ii. p. 109. on IV ECONOMY OF THE MUSSEL 117 In some of our low-lying coast districts mussels are a valuable protection against inundation. “An action for trespass was brought some time ago for the purpose of establishing the right of the lord of the manor to prevent the inhabitants of Heacham from taking mussels from the seashore. The locality is the fore-shore of the sea, running from Lynn in a north-westerly direction towards Hunstanton in Norfolk; and the nature of the shore is such that it requires constant attention, and no little expenditure of money, to maintain its integrity, and guard against the serious danger of inundations of the sea. Beds of mussels extend for miles along the shore, attaching themselves to artificial jetties running into the sea, thereby rendering them firm, and thus acting as barriers against the sea [and as traps to eatch the silt, and thus constantly raise the level of the shore]. Therefore, while it is important for the inhabitants, who claim a right by custom, to take mussels and other shell-fish from the shore, it is equally important for the lord of the manor to do his utmost to prevent these natural friends of his embankments and jetties from being removed in large quantities.” ! The fable that Bideford Bridge is held together by the byssi of Mytilus, which prevent the fabric from being carried away by the tide, has so often been repeated that it is perhaps worth while to give the exact state of the case, as ascertained irom a Town Councillor. The mussels are supposed to be of some advantage to the bridge, consequently there is a by-law for- bidding their removal, but the corporation have not, and never had, any boat or men employed in any way with regard to them. , Poisoning by mussels is much more frequent than by oysters. At Wilhelmshaven,? in Germany, in 1885, large numbers of persons were poisoned, and some died, from eating mussels taken from the harbour. It was found that when transferred to open water these mussels became innocuous, while, on the other hand, mussels from outside, placed in the harbour, became poisonous. The cause obviously lay in the stagnant and cor- rupted waters of the harbour, which were rarely freshened by tides. It was proved to demonstration that the poison was not due to decomposition; the liver of the mussels was the poisonous part. In the persons affected, the symptoms were of three 1M. S. Lovell, Edible Mollusks, p. 49. 2 Science, vii. p. 175. J 18 CULTIVATION OF THE SNAIL FOR FOOD CHAP. kinds, exanthematous (skin eruptions), choleraic, and paralytic. Cases of similar poisoning are not unfrequent in our own country, and the circumstances tend to show that, besides the danger from mussels bred in stagnant water, there is also risk in eating them when ‘out of season’ in the spawning time. Whelks are very largely employed for bait, especially in the cod fishery. The whelk fishery in Whitstable Bay, both for bait and for human food, yields £12,000 a year. Dr. Johnston, of Berwick, estimated that about 12 million limpets were annually consumed for bait in that district alone. The cockle fishery in Carmarthen Bay employs from 500 to 600 families, and is worth £15,000 a year; that in Morecambe Bay is worth £20,000. Cultivation of Snails for Food; Use as Medicine. — It was a certain Fulvius Hirpinus who, according to Pliny the elder,} first instituted snail preserves at Tarquinium, about 50 B.c. He appears to have bred several species in his ‘ cochlearia,’ keeping them separate from one another. In one division were the albulae, which came from Reate ; in another the ‘ very big snails’ (probably H. lucorum), from Illyria; in a third the African snails, whose characteristic was their fecundity; in a fourth those from Soletum, noted for their ‘nobility.’ To increase the size of his snails, Hirpinus fed them on a fattening mixture of meai and new wine, and, says the author in a burst of enthusiasm, ‘the glory of this art was carried to such an extent that a single snail-shell was capable of holding eighty sixpenny pieces.’ — Varro? recommends that the snaileries be surrounded by a ditch, to save the expense of a special slave to catch the run- aways. Snails were not regarded by the Romans as a particular luxury. Pliny the younger reproaches® his friend Septicius Clarus for breaking a dinner engagement with him, at which the menu was to have been a lettuce, three snails and two eggs apiece, barley water, mead and snow, olives, beetroot, gourds and truffles, and going off somewhere else where he got oysters, scallops, and sea-urchins. In Horace’s time they were used as a gentle stimulant to the appetite, for “Tis best with roasted shrimps and Afric snails To rouse your drinker when his vigour fails.” 4 1 Hist. Nat. ix. 82. 2 De re rustica, iii. 14. 8 Epistles, i. 15. 4 Hor. Sat. IL, iv. 58, tr. Conington. ¢ IV CULTIVATION OF THE SNAIL FOR FOOD 119 Escargotiéres, or snail-gardens, still exist in many parts of Europe, e.g. at Dijon, at Troyes and many other places in central and southern France, at Brunswick, Copenhagen, and Ulm. The markets at Paris, Marseilles, Bordeaux, Toulouse, Nantes, etc., are chiefly supplied by snails gathered from the open country, and particularly from the vineyards, in some of which Helix pomatia abounds. In the Morning Post of 8th May 1868 there is an account of the operation of clearing the celebrated Clos de Vougeot vineyard of these creatures. No less than 240 gallons were captured, at a cost in labour of over 100 francs, it being estimated that these snails would have dam- aged the vines to an extent represented by the value of 15 to 20 pipes of wine, against which may be set the price fetched by the snails when sold in the market. It is generally considered dangerous to eat snails at once which have been gathered in the open country. Cases have occurred in which death by poisoning has resulted from a neglect of this precaution, since snails feed on all manner of noxious herbs. Before being sent to table at the restaurants in the great towns, they are fattened by being fed with bran in the same way as oysters. The Roman Catholic Church permits the consumption of snails during Lent. Very large numbers are eaten in France and Austria at this time. At the village of Cauderon, near Bordeaux, it is the proper thing to end Carnival with especial gaiety, but to temper the gaiety with a dish of snails, as a fore- taste of Lenten mortification. The following species appear to be eaten in France at the present day: H. pomatia, aspersa, nemoralis, hortensis, aperta,’ pisana, vermiculata, lactea. According to Dr. Gray, the glassmen at Newcastle used to indulge in a snail feast once a year, and a recent writer informs us that H. aspersa is still eaten by working people in the vicinity of Pontefract and Knottingley.1 But in this country snails appear to be seldom consciously used as an article of food; the limitation is necessary, for Lovell tells us that they are much employed in the manufacture of cream, and that a retired (!) milkman pronounced it the most successful imitation known. Preparations made from snails used to be highly esteemed as 1 Roberts, Zoologist, 1885, p. 425. 120 SNAILS AS MEDICINE CHAP. a cure for various kinds of diseases and injuries. Pliny the elder recommends them for a cough and for a stomach-ache, but it is necessary “to take an uneven number of them.”’! Five African slugs, roasted and beaten to a powder, with half a drachm of acacia, and taken with myrtle wine, is an excellent remedy for dysentery. ‘Treated in various ways, snails have been considered, in modern times, a cure for ague, corns, web in the eye, scorbutic affections, hectic fevers, pleurisy, asthma, obstruc- tions, dropsy, swelling of the joints, headache, an impostume (whitlow), and burns. One of Pliny’s remedies for headache, which competes with the bones of a vulture’s head or the brain of a crow or an owl, is a plaister made of slugs with their heads cut off, which is to be applied to the forehead. He regards slugs as immature snails, whose growth is not yet complete (nondum perfectae). Lovell states that “a large trade in snails is carried on for Covent Garden market in the Lincolnshire fens, and that they are sold at 6d. per quart, being much used for consumptive patients and weakly children.” The custom still seems to linger on in some parts of the country. Mr. E. Rundle, of the Royal Cornwall Infirmary, gives his experience in the following terms: “ I well remember, some twelve years since, an individual living in an adjoining parish [near Truro] being pointed out to me as ‘a snail or slug eater. He was a delicate looking man, and said to be suffering from consumption. Last summer I saw this man, and asked him whether the statement that he was a ‘snail eater’ was true: he answered, ‘Yes, that he was ordered small white slugs — not snails — and that up till recently he had consumed a dozen or more every morning, and he believed they had done him good.’ There is also another use to which the country people here put snails, and that is as an eye application. I met with an instance a few weeks since, and much good seemed to have followed the lise. ( A reverend Canon of the Church of England, whose name I am not permitted to disclose, informs me that there was a belief among the youth of his native town (Pontypool, in Mon- mouthshire) that young slugs were ‘ good for consumption,’ and that they were so recommended by a doctor who practised in the town. The slugs selected were about ? inch long, “ such as 1 Hist. Nat. xxx. 15, 19. 2 Science Gossip, 1891, p. 166. IV PRICES PAID FOR SHELLS; E21 may be seen crawling on the turf of a hedge-bank after a shower of rain.” They were “ placed upon the tongue without any pre- vious preparation, and swallowed alive.” My informant himself indulged in this practice for some time, “ not on account of any gustatory pleasure it afforded, but from some vague notion that it might do him good.” A colleague of mine at King’s College tells me that the country people at Ponteland, near Morpeth, habitually collect Limazx agrestis and boil it in milk as a prophylactic against con- sumption. He has himself frequently devoured them alive, but they must be swallowed, not scrunched with the teeth, or they taste somewhat bitter. Snails have occasionally fallen, with other noxious creatures, under the ban of the Church. In a prayer of the holy martyr Trypho of Lampsacus (about 10th cent. A.D.) there is a form of exorcism given which may be used as occasion requires. It runs as follows: “ O ye Caterpillars, Worms, Beetles, Locusts, Grass- hoppers, Woolly-Bears, Wireworms, Longlegs, Ants, Lice, Bugs, Skippers, Cankerworms, Palmerworms, Snails, Earwigs, and all other creatures that cling to and wither the fruit of the grape and all other herbs, I charge you by the many-eyed Cherubim, and by the six-winged Seraphim, which fly round the throne, and by the holy Angels and all the Powers, etc. etc., hurt not the vines nor the land nor the fruit of the trees nor the vegetables of the servant of the Lord, but depart into the wild moun- tains, into the unfruitful woods, in which God hath given you your daily food.” Prices given for Shells. — Very high prices have occasionally been given for individual specimens, particularly about thirty or > forty years ago, when the mania for collecting was at its height. In those days certain families, such as the Volutidae, Conidae, and Cypraeidae, were the especial objects of a collector’s ardour, and he spared no expense to make his set of the favourite genus as complete as possible. Thus at Stevens’ auction-rooms in Covent Garden, on 21st July 1854, one specimen of Conus cedo nulli fetched £9: 10s., and another £16, a C. omaicus 16 guineas, C’. victor £10, and C. gloria maris, the greatest prize of all, £48: ls. At the Vernéde sale, on 14th Dec. 1859 two Conus omaicus fetched £15 and £22, anda C. gloria maris £34. At the great Dennison sale, in April 1865, the Conzdae fetched 122 PRICES PAID FOR SHELLS CHAP. IV extravagant prices, six specimens averaging over £20 apiece. Conus cedo nulli went for £18 and £22, C. omaicus for £12, C. malaccanus for 10 guineas (this and one of the cedo nulli being the actual specimens figured in Reeve’s Conchologia Iconica), C. cervus for £19 and C. gloria maris for £42. On 9th May 1866 a Cypraea Broderipi was sold at Stevens’ auction- rooms for £13, and at the Dennison sale a Cypraea princeps fetched £40, and C. guttata £42. The Volutidae, although not quite touching these prices, have yet done fairly well. Mr. Dennison’s Voluta fusiformis sold for £6: 1ds., V. papillaris for £5, V. cymbiola for £5: 15s., V. reticulata for eight guineas, and two specimens of the rarest of all Volutas, V. festeva, for £14 and £16, both being figured in the Conchologia. At the same sale, two unique specimens of Oniscra Dennisoni fetched £17 and £18 respectively, and, at the Vernéde sale, Ancillaria Vernédet was bought for £6: 10s., and Voluta piperata for oes WS: A unique specimen of a recent Plewrotomaria (quoyana F. and B.) was purchased by Miss de Burgh in 1873 for 25 guineas, and another species of the same genus (adansoniana Cr. and F.), of extraordinary size and beauty, is now offered for sale for about £100. ~~ Bivalves have never fetched quite such high prices as uni- valves, but some of the favourite and showy genera have gone near to rival them. On 22nd June 1869, at Stevens’, Pecten solaris fetched £4:5s., P. Reevii £4:8s., and Cardita varia 5 guineas. Mr. Dennison’s specimens of Pecten subnodosus sold for £7, of Corbula Sowerbyi for £10, of Pholadomya candida for £8 and £13, while at the Vernéde sale a Chama damicornis fetched £7. CHAPTER sV REPRODUCTION — DEPOSITION OF EGGS — DEVELOPMENT OF THE FERTILISED OVUM — DIFFERENCES OF SEX — DIOE- CIOUS AND HERMAPHRODITE MOLLUSCA — DEVELOPMENT OF FRESH-WATER BIVALVES REPRODUCTION in the Mollusca invariably takes place by means of eggs, which, after being developed in the ovary of the female, are fertilised by the spermatozoa of the male. Asarule, the eggs are ‘laid,’ and undergo their subsequent development apart from the parent. This rule, however, has its exceptions, both among univalve and bivalve Mollusca, a certain number of which hatch their young from the egg before expelling them. Such ovoviviparous genera are Melania, Paludina, Balea, and Coeliaxis among land and fresh-water Mollusca, and Cymba and many Littorina amongst marine. The young of Melania tuber- ewlata, in Algeria, have been noticed to return, as if for shelter, to the branchial cavity of the mother, some days after first quitting it. Isolated species among Pulmonata are known to be ovoviviparous, e.g. Patula Coopert, P. Hemphilli, and P. rupestris, Acanthinula harpa, Microphysa vortex, Pupa cylin- dracea and muscorum, Clausilia ventricosa, Opeas dominicensis, Rhytida inaequalis, etc. All fresh-water Pelecypoda yet exam- ined, except Dreissensia, are ovoviviparous. The number of eggs varies greatly, being highest in the Pelecypoda. In Ostrea edulis it has been estimated at from 300,000 to 60,000,000; in Anodonta from 14,000 to 20,000: in Unio pictorwm 200,000. The eggs of Doris are reckoned at from 80,000 to 600,000, of Loligo and Sepia at about 30,000 to 40,000. Pulmonata lay comparatively few eggs. Arion ater has been observed to lay 477 in forty-eight days (p. 42). Nests 123 124 EGGS OF LAND PULMONATA CHAP. of Helix aspersa have been noticed, in which the number of eggs varied from about 40 to 100. They are laid in little cup-shaped hollows at the roots of grass, with a little loose earth spread over them. The eggs of Testacella are rather large, and very elastic; if dropped on a stone floor they will rebound sharply several inches. The Cochlostyla of the Philippines lay their eggs at the tops of the great forest trees, folding a leaf together to serve as a protection. The eggs of the great tropical Bulimus and Achatina, together with those of the Macroén eroup of Helix (Helicophanta, Acavus, Panda) are exceedingly large, and the number laid must be decidedly less than in the smaller Pulmonata. Buli- mus oblongus, for instance, from Bar- bados, lays an egg about the size of a sparrows (Fig. 388), of the pharynx. ‘The visceral loop is in some cases long, and the two or three visceral ganglia are then situated at its posterior extremity. The nervous system of the Pulmonata is of a similar type, the visceral loop being often much shorter, and tending to draw in towards the central group of ganglia. The tentacular and optic nerves are, as usual, derived from the cerebral gang- lion, with which also the octocysts are probably connected by rather long nerves. A pair of buccal ganglia innervate the buccal mass, and are united by commissures with the right and loerperrés, twisted ; edAvs, straight. 2 With the exception of Actaeon, which is streptoneurous (Bouvier, Comptes Rendus, cxvi. p. 68). 204 STREPTONEURA AND EUTHYNEURA CHAP. left cerebral ganglia. The osphradial nerve springs from one of the ganglia on the visceral loop, the osphradium itself being situ- ated (in Limnaea) immediately above the pulmonary orifice and adjacent to the anus (Fig. 102). This massing of the ganglia is still better illustrated by the accompanying figure of Physa (Fig. 103), in which the animal is represented as if transparent, so that the ganglia and nerves are seen through the tissues. Of the streptoneurous Gasteropoda, the nervous system of Fic. 102. —I. Nervous system of Limnaea stagnalis L. The oesophagus has been cut and pulled forwards through the nerve-collar, so as to expose the lower surface of the buccal mass(dissected by F.B. Stead). B.M,‘buccal mass. B.G, buccal, C.G, cerebral, Os.G, osphradial, Pe.G, pedal ganglia. P1.G, pleural ganglia. Op.N, optic, Os.N, osphradial, Te.N, tentacular nerve. Ot, otocyst ; V.L, visceral loop. R, rectum, dotted in to show its position relative to the osphradium. II. Right side of the head of Lim- naea stagnalis. The over- hanging flap of the mantle has been cut in the middle line, and the right half twisted back, so as to expose the pul- ““®5__.0s.¢ monaryorifice,etc. The points N A A on the mantle edge were continuous before the mantle S was cut; the line BA is part of the free edge of the mantle. eh a An, anus; F, female genera- wooo" tive orifice ; J, portion of jaw; M, male generative orifice un- der right tentacle ; Os, osphra- dium ; P.O, pulmonary orifice. Fissurella aud Haliotis shows distinct points of similarity to that of the Amphineura. The pedal nerves are united by transverse commissures throughout their entire length, while a double com- missure unites the cerebral ganglia to the mass from which the pedal nerves proceed. In the great majority of the Streptoneura the ganglia (except the visceral) are more concentrated and the commissures are consequently much shorter. The accompanying figure of Cyclostoma, in which the animal is represented as in VII STREPTONEURA AND EUTHYNEURA 205 that of Physa just described, illustrates this grouping of the ganglia, the twist of the visceral loop, and the position of the visceral ganglia at its posterior end. Scaphopoda. — In the Scaphopoda the nervous system resem- bles that of the Pelecypoda. The cerebral and pleural ganglia lie close together, while the pedal ganglia are placed in the anterior part of the foot, connected with the cerebral ganglia by Fic. 103.— Nervous systemof Physa Fic. 104.—Example of a streptoneurous acuta Drap., showing the massing Gasteropod (Cyclostoma elegans Drap.): of the ganglia at the hinder end of c.g, c.g, cerebral ganglia; e, e, eyes; os, the pharynx: €,e, eyes; m, mouth; osphradium; of, ot, otocysts; p.g, p.y, m.l, m.l, mantle lappets; o,f, fe- pedal ganglia; pl.g, pl.g, pleural ganglia ; male generative orifice ; 0.m, male sp.g, supraintestinal ganglion; sb.g, sub- generative orifice ; os, osphradium. intestinal ganglion; ¢t.n, tentacle nerve; (After Lacaze-Duthiers.) v.g, visceral ganglion. (After Lacaze- Duihiers.) long commissures ; the visceral loop is rather long, and the two visceral ganglia are adjacent to the anus. Pelecypoda. — The nervous system in the Pelecypoda is ste simplest type in which well-marked ganglionic centres occur. The ganglia are few, symmetrically placed, and are usually at a considerable distance apart. There are, as a rule, three distinct pairs of ganglia, the cerebral (cerebro-pleural), pedal, and visce- ral. The cerebral are formed by the fusion of the cerebral and pleural ganglia, which, however, in some cases (Protobranchiata ) continue distinct.1_ They lie above or on each side of the mouth, 1 This fusion of the cerebral and pleural ganglia and the consequent union of 206 VALUE IN CLASSIFICATION CHAP. | united by a commissure of varying length. Another pair of” commissures unites them with the pedal ganglia, which are placed at the base of the foot, and are usually very close to- gether, sometimes (as in Anodonta) becoming partially fused. | The length of these commissures depends upon the distance between mouth and foot; thus they are very long in Mya and Modiola, and very short in Pecten. In cases where the foot is rudimen- tary. or becomes aborted through ° disuse (e.g: Ostrea), the pedal ganglia may dwindle or disappear altogether. The visceral ganglia are on the ventral side of the posterior adductor muscle, beneath the rectum, and innervate the branchiae, osphradia, and _ the whole of the visceral sac. NOs Yoga D>, es ae WW astz, Lier ILE LP 255 7, LD o sa Fic. 108. —Jaws of A, Triton australis Lam., Sydney; B, Ampullaria fasciata Reeve, Demerara; C, Calliostoma punctulatum Mart., New Zealand; D, Cyclophorus atramentarius Sowb., Sanghir; all x 15. » Rw) Siw tore 3 Fic. 109. — Jaws of A, Chromodoris gracilis Iher., x 15; B, Scyllwea pelagica L., x T; C, Pleurobranchus plumula Mont., x 10; D, Pleurobranchaea Meckelii Lam., x 3. Nudibranchiata the jaws are of great size and beauty of orna- mentation (Fig. 109). VIII THE RADULA 213 The carnivorous genera, whether marine (e.g. Conus, Murez, Buccinum, Nassa) or land (e.g. Testacella, Glandina, Streptazis, Ennea), are entirely destitute of jaws, the reason probably being that in all these cases the teeth of the radula are sufficiently powerful to do the work of tearing up the food without the aid of a masticatory organ as well. Jaws are also wanting in the Heteropoda, and in many of the Nudibranchiata and Tecti- branchiata. In the Cephalopoda the jaws, or ‘ beaks,’ as they are called, are most formidable weapons of attack. In shape they closely resemble the beaks of a parrot, but the hook on the dorsal side of the mouth does not, as in birds, close over the lower hook, but fits under it. Powerful muscles govern these mandibles, which must operate with immense effect upon their prey cHie. 110). The Radula.1— When the food has passed beyond the opera- 1 The whole of the radulae and jaws figured in this work are taken from the original specimens in the collection of the Rev. Prof. H. M. Gwatkin, who has always been ready to give me the run of his cabinets, which probably contain the finest series of radulae in the world. To his kindness I owe the following description of the process of mounting: ‘‘ The first step is to obtain the radula. ’ Dissection is easy in species of a reasonable size. On opening the head from above; so as to lay open the floor of the mouth, the radula itself is seen in most of the marine species, though in others it is contained in a sort of proboscis ; and in the Pulmonata and others the student will find the buccal mass, with commonly a brown mandible at its front end, and the lingual ribbon in its hinder part. The teeth may be recognised by their silvery whiteness, except in a few cases like Patella and Chiton, where they are of a deep brown colour. When obtained, the radula may be cleaned by boiling in a solution of caustic potash. There is no risk of injury if the solution is not too strong. ‘Smaller species may be treated more summarily. The proboscis, the buccal mass, or even the whole animal may be thrown into the potash solution and boiled till scarcely anything is left but the cleaned radula. Remains of animals dried inside the shell may be similarly dealt with, after soaking in clean water. With a little care, this process will answer for shells down to the size of Ancylus or Rissoa. The very smallest (Carychium, Tornatellina, Skenea, etc.) must be crushed on the slide and boiled on it, after removing as much as possible of the broken shell. The radula can then be searched for under the microscope, and washed and mounted on the slide. ‘The student must be warned that though the general process is simple, there are difficulties in particular cases. In the Pulmonata, for example, mem- branes on both sides of the radula need careful removal. Murex, Purpura, and most of the Taenioglossa have the side teeth folded down over the central, so that the arrangement is not well seen till they have been brushed back. The ‘Cones, again, have no basal membrane at all, so that if the potash is not used with great care, the single teeth will fall asunder and be lost. Perhaps the worst case is where a large animal has a radula as small as that of a Rissoa, 214 FUNCTIONS AND POSITION OF RADULA CHAP. tion of the jaw, it comes within the province of the radula, the front part of which perhaps co-operates to a certain extent with Fic. 111.— Patella vulgata L., show- ing the normal position of the radula, which is doubled back in a bow; the shell has been re- moved, and the whole visceral mass is turned forward, exposing the dorsal surface of the muscular foot: gr, longitudinal groove on this surface; 7, i, intestine; J, liver; m, m, mantle edge; mu, Fic. 110. — Jaws of Sepia: A, in situ within the buccal mass, several of the arms having been cut away ; B, removed from the mouth and slightly enlarged. muscles (cut through) fastening the visceral mass to the upper sides of the foot ; ov, ovary; 7, radula; uf, upper or dorsal surface of the foot. the jaw in performing the biting process. The function of the like Turritella, Harpa, or Struthiolaria, or where the radula is almost filmy in its transparency, like those of Actaeon and the small Scalaria. ‘‘When once the radula is laid out, the mounting ‘is commonly easy. Canada balsam makes it too transparent. Fluids may be used, and are almost necessary for thick radulae like those of large Chitons; but the best general medium is glycerine jelly. It runs under the cover glass by capillary attraction, and may be boiled (though only for a moment) to get rid of air bubbles. It should then be left unfinished for several weeks. If cracks appear, the reason is either that the jelly is a bad sample, or that it has been boiled too long, or (commonly) that the object is too thick; and there is not often any difficulty in remounting. I have no serious complaint of want of permanence against the medium, if I may speak from a pretty wide experience during the last twenty years.”’ Vil TEETH OF THE RADULA 215 radula as a whole is to tear or scratch, not to bite; the food passes over it and is carded small, the effect being very much the same as if, instead of dragging a harrow over the surface of a field, we were to turn the harrow points upwards, and then _ drag the field over the harrow. The radula itself is a band or ribbon of varying length and breadth, formed of chitin, generally almost transparent, some- times beautifully coloured, especially at the front end, with red or yellow.! It les enveloped in a kind of membrane, in the floor of the mouth and throat, being quite flat in the forward part, but usually curving up so as to line the sides of the throat farther back, and in some cases eventually forming almost a tube. The upper surface, z.e. the surface over which the food passes, is covered with teeth of the most varied shape, size, number, and disposition, which are almost invariably arranged in symmetrical rows. ‘These teeth are attached to the cartilage on which they work by muscles which serve to erect or depress them ; probably also the radula as a whole can be given a for- ward or backward motion, so as to rasp or card the substances which pass over it. The teeth on the front part of the radula are often much worn (Fig. 112), and probably fall away by degrees, their place being taken by others successively pushed up from behind. At the extreme hinder end of the radula the teeth are in a nascent condition, and there are often as many as a dozen or more scarcely developed rows. Here, too, lie the cells from which the teeth are originally formed. The length and breadth of the radula vary eae in differ- ent genera. In Littorina it is very narrow, and several times the length of the whole animal. It is kept coiled away like a watch-spring at the back of the throat, only a small proportion of the whole being in use. I have counted as many as 480 rows in the common Littorina littorea. In Patella it is often longer than the shell itself, and if the radula of a large specimen be freshly extracted and drawn across the hand, the action of the hooks can be plainly felt. In Aerope, the Turbinidae generally, and Haliotis it is very large. In Turritella, Aporrhais, Cylichna, 1 The substance both of the jaw and radula is neither crystalline nor cel- lular, but laminated. Chitin is the substance which forms the ligament in bivalves, the ‘pen’ in certain Cephalopoda, and the operculum in many uni- valves. Neither silica nor keratine enter into the composition of the radula. 216 SIZE OF RADULA— PRESENCE OR ABSENCE \ GEEEE: Struthiolaria, and the Cephalopoda it is small in proportion to the size of the animal. -In the Pul- monata generally it is very broad, the length not exceeding, as a rule, thrice the breadth; in most other groups the breadth is inconsider- able, as compared to the length. The Radula is wanting in two families of Prosobranchiata, the Eulimidae and Pyramidellidae, which are consequently grouped together as the section Gymno- glossa. It is probable that in _ these cases the radula has aborted PE as ate ee ee through disuse, the animals hav- Reeve, Panama), much worn by ing taken to a food which does not aaa require trituration. Thus several genera contained in both these families are known to live para- sitically upon various animals — Holothurians, Echinoderms, etc. —nourishing themselves on the juices of their host. In some cases, the development of a special suctorial p~oboscis compen- sates for the loss of radula (see pp: 16-77). In Harpa there is no radula in the adult, though it is present in the young form. No explanation of this fact has yet been given. It is also absent in the Coralliophilidae, a family closely akin to Purpura, but invariably parasitic on corals, and probably nourished by their exudations. There is no radula in Entoconcha, an obscure form parasitic on the blood-vessels of Synapta, or in Meomenia, a genus of very low organisation, or in the Tethyidae, or sea- hares, or in one or two other genera of Nudibranchiata. The number of teeth in the radula varies greatly. When the teeth are very large, they are usually few in number, when small, they are very numerous. In the carnivorous forms, as a rule, the teeth are comparatively few and powerful, while in the phytophagous genera they are many and small. Large hooked and sickle-shaped teeth, sometimes furnished with barbs like an arrow-head, and poison-glands, are characteristic of genera which feed on flesh; vegetable feeders, on the contrary, have the teeth rounded, and blunter at the apex, or, if long and narrow, so slender as to be of comparatively little effect. : t 4 VIII NUMBER AND ARRANGEMENT OF TEETH 217 Genera which ar normally vegetarian, but which will, upon occasion, eat fle 1, e.g. Limax and Hyalinia, exhibit a form of teeth intermediate between these two extremes (see Fig. 140, A). In Chaetoderma there is but one tooth. In Aeolis coronata there are about 17, in A. papillosa and Elysia viridis about 19, in Glaucus atlanticus about 21,in Fiona nobilis about 28. In the common whelk (Bucecinum undatum) there are from 220 to 250, in the common periwinkle about 3500. As many as 8348 have been counted in Limnaea stagnalis, about 15,000 in Helix aspersa (that is, about £00,000 to the squsre inch), about 30,000 in Limax maximus, and as many as 40,000 in Helix Gthies- breghti, a large species from Mexico; they are very numerous also in Nanina, Vitrina, Gadinia, and. Actaeon. But Umbrella stands far and away the first, as far as number of teeth is con- erned. In both U. mediterranea and U. indica they entirely baffle calculation, possibly 750,000 may be somewhere near the truth. The teeth on the radula are almost ney disposed in a kind of pattern, exactly like the longitudinal rows. of colour in a piece of ribbon, down the centre of which runs a narrow stripe, and every band of colour on one side is repeated in the same relative position on the other side... The middle tooth of each row — the rows being counted across the radula, not longi- tudinally —is called the central or rachidian tooth; the teeth next adjacent on each side are known as the laterals, while the outermost are styled uneint or marginals. As a rule, the dis- tinction between the laterals and marginals is fairly well indi- cated, but in the Helicidae and some of the Nudibranchiata it is not easy to perceive, and in these cases there is a very gradual passage from one set to the other. | The central tooth is nearly always present. It is wanting in certain groups of Opisthobranchiata, some of the carnivorous Pulmonata, and in the Conidae and Terebridae, which have lost the laterals as well. Voluta has lost both laterals and marginals in most of the species, and the same is the case with Harpa. In Aeolis, Elysia, and some other Nudibranchiata the radula ~ consists of a single central row. Other peculiarities will be described below in their proper order. The extreme importance of a study of the radula depends upon the fact, that in each species, and a fortiori in each genus VALUE IN CLASSIFICA? and family, the radula is characteristic. In¢ the differences exhibited are naturally but slight, but in well- marked species the differences are considerable. The radula, ~ therefore, serves as a test for the distinction : cae and species. — For instance, in the four known recent genera of the family ‘ Strombidae, viz. Strombus, Pteroceras, Rostellaria, and | lum, the radula is of the same general type throughout, but wi distinct modifications for each genus; and the same is true, though to a lesser extent, for all the species hitherto examined — in each of the genera. ‘These facts are true for all known genera, differences of the radula corresponding to and emphasising those other differences which have caused genera to be constituted. The radula therefore forms a basis of classification, and it is © found especially useful in this respect in dealing with the largest class of all, the Gasteropoda, and particularly with the chief section of this order, the Prosobranchiata. Thus we have— ly allied species | (a) Toxoglossa a (b) Rachiglossa | £ Monotocardia + (c) Taenioglossa ” | (d) Ptenoglossa ‘Sas | (e) Gymnoglossa (f) Rhipidoglossa Prosobranchiata | (g) Docoglossa1 Diotocardia { (a) Toxoglossa. — Only three families, Terebridae, Conidae, and Cancellariidae, belong to this section. There is no central tooth, and no laterals, the radula consisting simply of large mar- ginals on each side. In Conus these are of great size, with a blunt base which contains a poison-gland (see p. 66), the con- tents of which are carried to the point by a duct. The point is always singly and sometimes doubly barbed (Fig. 116). When extracted, the teeth resemble a small sheaf of arrows (Figs. 118, 115). A remarkable form of radula, belonging to Spirotropis (a subgenus of Drillia, one of the Conidae), enables us to explain the true history of the radula in the Toxoglossa. Here there are five teeth in a row, a central tooth, and one lateral and one marginal on each side, the marginals being very similar in shape to the characteristic shafts of the Conidae (Fig. 114). It is evident, then, that the great mass of the Toxoglossa have lost 1 réfov, arrow; pdaxis, ridge, sharp edge; raivla, ribbon; mrnvés, winged ; yupvds, bare; pirls, fan; doxds, beam. VIII FORMULAE OF TEETH 219 both their central and lateral teeth, and that those which remain are true uncini or marginals. Spirotropis appears to be the soli- tary survival of a group retaining the primitive form of radula. The arrangement of teeth in all these sections is expressed by a formula applicable to each transverse row of the series. The central tooth, if present, is represented by 1, and the laterals and marginals, according to their number, on each side of the i Fig. 114.— Portion of radula of Spiro- tropis carinata Phil., Norway. x70. Fic. 113. — Radula of Bela turricula Mont. Fie. 115.— Eight teeth from the radula x 70. of Terebra caerulescens Lam. x 60. central figure. Thus the typical formula of the Toxoglossa is 1.0.0.0.1, the middle 0 standing for the central tooth which is absent, and the 0 on each side of it for the absent laterals; the 1 on each extreme represents the one uncinus in each row. Thus the formula for Spirotropis, which has also one lateral on each side and a rachidian or central tooth, is 1.1.1.1.1. Often _ the formula is given thus: ae oe where 80 and 42 stand for the average number of rows of teeth in Conus and Spirotropis respectively ; the same is sometimes expressed thus: oabe.0.1 x 30; 1.1.1.1.1 x 42. 220 RADULA OF THE RACHIGLOSSA CHAP. (6) The Rachiglossa comprise the 12 families Olividae, Harpi- dae, Marginellidae, Volutidae, Mitridae, Fasciolariidae, Turbi- nellidae, Buccinidae, Nassidae, Columbellidae, Muricidae, and Fic. 117. — Portion of the radula of Melongen vespertilio Lam., Ceylon. x 30. Fie. 116.—A tooth - from the radula of Conus imperi- alis L.,S. Pacific, x 50, showing barb and poison duct. Fic. 118. — Portion of the radula of Eburna japonica Sowb., China. x 30. Fic. 119.— Portion of the radula of Murex regius Lam., Panama. x 60. Coralliophilidae. Certainly most and probably all of these fam- ilies are or have been carnivorous, the Coralliophilidae being a degraded group which have become parasitic on corals, and have lost their teeth in consequence. The characteristics of the VIII RADULA OF THE RACHIGLOSSA 221 group are the possession of a central tooth with from one cusp (Boreofusus) to about fourteen (Bullia), and a peer lateral more or less cuspidate, the outer cusp of all being generally much the larg- est. Thus in Melongena respertilio (Fig. 117) the central tooth is tri- cuspid, the central cusp being the smallest, while 5... 199 _ portion of the radula of Imbricaria the laterals are bicuspid 3 marmorata Swains. x 80. in Hburnajaponica (Fig. 118) the central tooth is 5-cusped, the two outer cusps being much the smallest. The teeth, on the whole, are sharp and hooked, Fic. 121.— Three rows of teeth from the radula of F'asciola- ria trapezium Lam. x 40. with a broad base and formidable cutting edge. In the Olividae, Turricula, Buccinopsis, and the Muricidae the laterals are unicus- pid and somewhat degraded (Fig. 119). In Mitra and the Fasciolariidae they are very broad and finely equally toothed like a comb (Figs. 120, 121). The whole group is desti- tute of marginals. Several remarkable peculiarities occur. Harpa loses the radula altogether in the adult. In the young it has lost only the laterals, and consists of nothing but the central tooth. 2A Pe a feet Marginella has no laterals; the central tooth Cymbium diadema 18 Small and comb-shaped, with blunt cusps. lie Strait. In Voluta the laterals are generally lost, but X 40. . ° ° in Volutomitra and one species of Voluta! they are retained. ‘The central tooth usually has three strong cusps, 1V. concinna, according to Schacko (Conch. Mitth. i. p. 126, Pl. xxiv. f. 5); the lateral is large, strong, unicuspid on a broad base. gop’ DEGRADED AND ABNORMAL RADULA CHAP. and is very thick and coloured a deep red or orange (Fig. 122); in the subgenus Amoria it is unicuspid, in shape rather like a spear-head with broadened wings ; in Volutolyria it is of a different type, with numerous unequal den- ticulations, something like the laterals of Mitra or Fasciolaria. Of the Mitridae, Cylindromitra has lost the laterals. Among the Buccinidae, Buccinopsis possesses a curiously degraded radula, the central tooth having no cusps, but being reduced to a thin basal plate, while the laterals are also weakened. This degradation from the type is a remarkable feature among radulae, and appears to 5 be characteristic, sometimes of a Fic. 123. — Examples of degraded forms whole family 2 oe the Columbelli- of radula: A, Cantharus pagodus dae (Fig. 123 B), sometimes of Reeve, Panane (naseentend), 40; genus, sometimes again of a portion ; B, Columbella varia Sowb., Single species. Thus in Cantha- Panama, x00. rus (a subgenus of Buccinum) the radula is typical in the great majority of species, but in C. .pagodus Reeve, a large and well-grown species, it is most remarkably degraded, both in the central and lateral teeth (Fig. 123, A). This circumstance is the more singular since “es (NE Fia. 124. — Three rows of the radula of Sistrum spectrum Reeve, Tonga. x8 The laterals to the right are not drawn in. Cee Maras C. pagodus lives at Panama side by side with C. ringeus and C’. insignis, both of which have perfectly typical radulae. It is probable that the nature of the food has something to do with the phenomenon. Thus Sistrwm spectrum Reeve was found to possess a very aberrant radula, not of the common muricoid VIII RADULA OF THE TAENIOGLOSSA 223 type, but with very long reed-like laterals.” This singularity was a standing puzzle to the present writer, until he was fortu- nate enough to discover that S. spectrum, unlike all other spe- cies of Sistrum, lives exclusively on a branching coral. The dental formula for the Rachiglossa is thus 1.1.1, except in those cases where the laterals are absent, when it is 0.1.0. (¢) The Taenioglossa comprise 46 families in all, of which the most important are Tritonidae, Cassididae, Cypraeidae, Strombidae, Cerithiidae, Turritellidae, Melaniidae, Littorinidae, Rissoidae, Paludinidae, Ampullariidae, Cyclophoridae, Cyclo- Fig. 125. — Portion of the radula of Cassis sulcosa Born., x40. The marginals to the right are not fully drawn. stomatidae, and Naticidae. The radula is characterised by a central tooth of very variable form, the prevailing type being multicuspid, the central cusp the largest, on a rather broad base ; a single lateral, which is often a broad plate, more or less cusped, and two uncini, rather narrow, with single hooks, or slightly Fie. 126.—Four rows of teeth SW YY TewWA from the radula of Vermetus (¥ eae Gam grandis Gray, Andamans. (A oN \ S x 40. Lao, Vig: tl A o\\ Av— pl cusped. The accompanying figures of Cassis, Vermetus, and Cypraea, and those of Lnttorina and Cyclophorus given on pp. 20, 21, are good examples of typical taenioglossate radulae. In Homalogyra the radula is much degraded, the central tooth is large and trianglar on a broad base, the lateral is represented only by a thin oblong plate, and the uncini are absent. In some species of Jeffreysia the uncini are said to be absent, while present in others. Lamellaria has lost both its uncini, but the radula of the allied Velutina is quite typical. A peculiar feature in this group is the tendency of the marginals to increase in number. A stage in this direction is perhaps 224 RADULA OF THE TAENIOGLOSSA CHAP. seen in Ovula, Pedicularia, and the Cyclostomatidae. Here the outermost of the two marginals is by far the larger and broader, and is strongly pectinated on its upper edge; in the C'yclostoma- Fig. 127.—Two rows of the radula of Cypraea tigris L. Xx 30. tidae the pectinations are rather superficial; in Ovula (where both marginals are pectinated) they are decidedly deeper; in Pedicularia they are deeper still, and make long slits in the tooth, tending to subdivide it altogether. In. Turritella the number of marginals is said to vary from none (in 7’. acicula) to three (7. triplicata), but the fact wants confirmation. Solarium is an aberrant form, possessing simply a number of long uncini, which recall those of Conus or Pleurotoma, and is therefore hard to classify ; the allied Yorinia has a radula which appears allied to Ovula or Pedicularia. In Triforis the teeth are identical throughout, very small, about 27 in a row, tricuspid on a square base, cusps short. The normal formula of the Taenioglossa is 2.1.1.1.2; in Lamellaria, 1.1.1; in Triforis, 13.1.13, or thereabouts. (d) Ptenoglossa.— This section consists of two families only, which cer- tainly appear remarkably dissimilar in general habits and appearance, viz., the Ianthinidae and Scealarii- a Lu —_ ee dae. In all probability ———- as ~ their approximation is only provisional. The Fia. 128. — Portion of the radula of Janthina radula, which in Janthina comniunis Lam. x 40. , ; is very large, and in Sca- laria very small, possesses an indefinite number of long hooked tie , RES 4 vil ' _ RADULA OF THE PTENOGLOSSA, ETC. 225 teeth, of which the outermost are the largest. The central tooth, if present (it does not occur in Lanthina), is the smallest in the series, and thus recalls the arrangement in some of the carnivorous Pulmonata (p. 232). In Janthina the radula is formed of two large divisions, with a gap between them down the middle. The formula is o.1.00 or o.0.00 according as the central tooth in Scalaria is or is not reckoned to exist. (e) Gymnoglossa. — In the absence of both jaw and radula it is not easy to classify the two families (Eulimidae and Pyra- midellidae) which are grouped under this section. Fischer regards them as modified Ptenoglossa; one would think it more natural to approximate them to the Taenioglossa. ERK at: Ve tARAY | Fic. 129. Ber aehion of the radula of Margarita umbilicalis Brod., Labrador. x 75 and 300. (f) Rhipidoglossa.— This section consists of seventeen families, the most important being the Helicinidae, Neritidae, Turbinidae, Trochidae, Haliotidae, Pleurotomariidae, and Fissu- rellidae. The radula is characterised by — (1) The extraordinary development of the uncini, of which there are so many that they are always reckoned as indefinitely numerous. They are long, narrow, hooked, and often cusped at the top, and crowded together like the ribs of a fan, those at the extreme edge not being set straight in the row, but curving away backwards as they become smaller; in Solariella alone, where there are from five to ten, can they be counted. (2) The varying number of the laterals. The average num- VOL. IJ Q 226 RADULA OF THE RHIPIDOGLOSSA CHAP, ber of these is five on each side; in some cases (Livona) there are as many as nine, in some (Neritopsis) only three. The lateral next to the uncini (which is specially large in the Neritidae, and is then known as the capituliform tooth) is regarded by some authorities as the first uncinus, by others as the sole representative of the laterals, the teeth on the inner side of it being reckoned as multiplied central teeth. Accord- ing to this latter view, Lzvona will have as many as seventeen central teeth. Taking five as the average number of ‘ laterals,’ we shall have the following different ways of constituting the © rhipidoglossate formula, the first being that to which preference is given, Viz.: — (1) ™.5.1.5.00, 7.2. one central, five laterals, including the ‘last lateral’ tooth. (2) (o.1).4.1.4.(1.00 ), regarding the ‘last lateral’ as first uncinus, but specialising it by a number. (8) o.1.(4.1.4).1.0 , regarding the ‘last lateral’ as the only lateral. In the Neritidae and the derived fresh-water genera (Weritina, Navicella) the first lateral, as well as the capituliform tooth, is Fic. 130. — Portion of the radula of Nerita albicilla L., Andaman Is., with central tooth highly magnified : c, c, the capituliform tooth. x 40. very large, and in shape rather like the blade bone of a shoulder of mutton; the intervening laterals are very small. In Wer- topsis (a degraded form) the central tooth and first lateral are entirely wanting. In the neritiform land-shells (Helicina, Proserpina) the first lateral is no larger than the others, while the capituliform tooth is enormous. Hydrocena is a very aber- rant and apparently degraded form; the laterals between the first and the capituliform tooth are all wanting. In Haliotis, Scissurella, and Pleurotomaria the five laterals are of fairly vin RADULA OF THE DOCOGLOSSA 227 equal size; in Fissurella we again meet with a large capituliform tooth, with very small laterals. (g) The Docoglossa are in direct contrast with the Rhipido- glossa in possessing few and strong teeth, instead of many and weak. ‘There are only three families, Acmaeidae, Patellidae, and Lepetidae. In some of the Acmae- idae there are not more than two teeth in a row, while in no species are there more than twelve. The radula is, however, very long; there are as many as 180 rows in Patella vulgata. The teeth are thick, generally of a very deep red horn colour, rather opaque. The cartilage in which they are set is remarkably thick, and in some species whose teeth are very few Fic. 131.— Portion of the radula ‘ : 5 Z of Patella cretacea Reeve, a considerable portion of this cartilage geen in half profile. x 40. is left quite bare. Although the teeth are so few, the arrangement is by no means simple. The special feature of the group is the multipli- cation of identical centrals. Of these there are two in Acmaea, and four, as arule, in Patella. Thus in these two genera there is seldom an absolutely central tooth. Either laterals or marginals are liable to be lost, but there are never more than two of either in Aemaea, and never more than two laterals and three marginals in Patella. Thus the formula varies from 0.0.(1 + 0 +1).0.0 in Fic. 132. — Two rows of the radula of Ptero- trachea mutica Les., Naples. x 60. Pectinodonta, 2.2..1+0+1).2.2 in Oollisellina (both Acmaei- dae), to 3.2.1 +0+41).2.3 in Patinella, and 3.1.2+0+4 2).1.3 in Patella proper. In the Lepetidae there is an absolutely central tooth, which appears to be made up of the coalescence of several teeth, no laterals, and about two marginals; formula, 2-0.1.0.2, 228 RADULA OF HETEROPODA AND AMPHINEURA CHAP. ~The radula of the Heteropoda is quite characteristic, and shows no sign of affinity with any other Prosobranchiate. The central tooth is large, broad, tricuspid, and denticulated on a broad base; the single lateral is strong, often bicuspid; the two marginals simple, long, falciform; formula, 2.1.1.1.2 (Fig. 132). Amphineura.—(a) Polyplacophora.— The radula of the Chitonidae is quite unique. It resembles that of the Docoglossa in being very long, and composed of thick and dark horn-col- oured teeth. The number of teeth, however, is considerably Fig. 1B eaeae Portion of the radula of Chiton (Acanthopleura) spiniger Sowb., An- damans, x 30; B, portion of the radula of Dentalium entalis L., Clyde, x 50. greater, amounting almost invariably to seventeen in each row. There are three rather small central teeth, the two outer of these being similar; next comes a very large lateral (the major lateral), usually tricuspid, which is followed by two much smaller laterals, which are scarcely more than accessory plates; then a very large and arched marginal (the major uncinus), at the outer side of which are three accessory plates. Some con- sider there is only one central tooth, and count the two small teeth on each side of it as laterals. | Thus the formula is either (8+1).(2+1) .8.(14+2).€1+3) or (84+1).(24141) .1.14+14+2).(14+8). (6) Aplacophora.— Of this rather obscure order, Chaetoderma has a single strong central tooth, Weomenia has no radula. VIII RADULA OF OPISTHOBRANCHIATA 229 Proneomenia and Lepidomenia have about twenty falciform teeth, much larger at one end of the radula than the other; formula, 0.1.0. Opisthobranchiata. — The radula of the Opisthobranchiata is exceedingly variable in shape, size, and number and character of teeth. Not only do allied families differ greatly from one another, but allied genera often possess radulae widely distinct Fic. 134. — Two teeth from the radula of ‘, Aeolis papillosa L. x 55. ‘ in plan. Thus, among the Polyceridae, Goniodoris has no cen- tral tooth, one large lateral and one marginal (form. 1.1.0.1.1); Doridunculus the same, with five marginals (form. 5.1.0.1.5); Lamellidoris one each of median, laterals, and marginals (1.1.1.1.1); Zdalia, Ancula, and Thecacera the same as Gonio- doris ; Crimora several each of laterals and marginals. Even species of the same genus may differ; thus the formula for Aeolis papillosa is 0.1.0, but for Ae. Landsbergi 1.1.1; for Philine aperta 1.0.1, but for Philine pruinosa 6.0.6. : It must not be forgotten, however, that a simple repetition of the same tooth, whether lateral or marginal, does not nec- essarily constitute an important characteristic, nor does the presence or absence of a central tooth. In most of the cases mentioned above, the difference in the number of laterals and marginals is due to the multiplication of identical forms, while the central tooth, when present, is often a mere plate or narrow block without cusps, whose presence or absence makes little difference to the character of the radula as a whole. There appear to be three well-marked types of radula among the Opisthobranchiata. (a) Radula with a single strong central tooth, rows few. 230 RADULA OF OPISTHOBRANCHIATA CHAP. This form is characteristic of the Aeolididae, Fionidae, Glaucidae, Dotoidae, Hermaeidae, Elysiidae (Fig. 185), and Limapontiidae. In the Aeolididae it is sometimes accompanied by a single lateral. The same type occurs in Oxynoe, and in Lobiger (= Lophocercus). (6) Radula with the first lateral very strongly developed. This type may take the form of (1) a single lateral, no central or marginals, e.g. Onchidoris, Scaphander (Fig. 187, A), Philine (certain species), Rengicula, or (2) first lateral strongly devel- oped, and repeated in succeeding laterals (2-6) on a smaller scale, e.g. Philine (certain species). A few marginals are some- SS SSS Te Ki $Y y «, . s \ ee ig =S NY YN), (hac SN =y HENNE ZZ LSP IOS Fic. 135.— Radula of Elysia Fic. 136. — Portion of the radula viridis Mont. x40. Type of Gadinia peruviana Sowb., (a). Chili. x 250. Type (c). times added, e.g. in Polycera, Lamellidoris (where there is a degraded central tooth, Fig. 137, B), Zdalia, and Anecula. (e) Radula with an indefinite number of marginals, laterals Gf present) merging into marginals, central tooth present or absent, inconspicuous, teeth all very small. This type of radula, among the Nudibranchiata, is characteristic of certain subgenera of Doris (e.g. Chromodoris, Aphelodoris, Casella, Centrodoris), of Hypobranchiaea and Pleurophyllidia; among the Tectibranchiata, of Actaeon, many of the Bullidae, Aplustrum, the Aplysiidae, Pleurobranchus, Umbrella and Gadinia (Figs. 136 and 187, C). In the Pteropoda there are two types of radula. The Gym- nosomata, which are in the main carnivorous, possess a radula with a varying number (4-12) of sickle-shaped marginals, cen- tral tooth present or absent. In the Thecosomata, which feed on a vegetable diet, there are never more than three teeth, a central and a marginal on each side; teeth more or less cusped on a square base. VIII RADULA OF PULMONATA 231 — Pulmonata. — The radula of the Testacellidae, or carnivo- rous land Mollusca, is large, and consists of strong sickle- shaped teeth with very sharp points, arranged in rows with or without a central tooth, in such a way that the largest teeth are often on the outside, and the smallest on the inside of the row (as in Phytida, Fig. 189). The number and size of the teeth vary. In Testacella and Glandina, they are numerous, consist- ing of from 30 to 70 in a row, with about 50 rows, the size throughout being fairly uniform. In Aerope they are exceed- Fie. 137.— Portions of the radula of Opisthobranchi- ata, illustrating types (b) and (c); A, Scaphander lig- narius L.; A’, one of the teeth seen from the other side, x 40; B, Lamellidoris bilamellata L., Torbay, x 60; C, Hydatina physis L., E. Indies, x 75. ingly large, and only eight in a row, the outermost marginal being probably the largest single tooth in the whole of the Mollusca. The central tooth is always obscure, being, when present, simply a weaker form of the weakest lateral; in genera with only a few teeth in a row it is generally absent altogether. The first family: of jaw-bearing snails, the Selenitidae, is distinctly intermediate. The possession of a jaw relates it to the main body of Helicidae, but the jaw is not strong, while the teeth are still, with the exception of the central, thoroughly -Testacellidan. The central tooth is quite rudimentary, but it is 232 RADULA OF PULMONATA CHAP. something more than a mere weak reproduction of the marginals. There are no true laterals. The Limacidae show a further stage in the transition. Here the central tooth has a definite shape of its own, tricuspid on a broad base, which is more or less repeated in the first laterals; these, as they approach the marginals, Fie. 138. — Portion of the radula of Glandina trun- cata Gmel. x 40. eradually change in form, until the outer marginals are again thoroughly Testacellidan This is the general form of radula, varied more or less in different genera, which occurs in NVanina, Helicarion, Limax, Parmacella, and all the subgenera of Zonites. It is certain that some, and probable that all of these genera will, Fie. 139. — Portion of the radula of Rhytida Kraussit Pfr., S. Afmiea, x 25. on occasion, eat flesh, although their usual food appears to be vegetable. The jaw is more powerful than in the Selenitidae, but never so large or so strongly ribbed as in Helix proper. When we reach the Helicidae, we arrive at a type of radula 1 In some cases (e.g. Hyalinia inornata) the laterals are very few, while in Zonites laevigatus the first side tooth is more of a marginal than a lateral. vil RADULA OF PULMONATA 233 in which the aculeate form of tooth—so characteristic of the Agnatha — disappears even in the marginals, and is replaced by teeth with a more or less quadrate base; the laterals, which are always present, are intermediate in form between the central and the marginals, and insensibly pass into the latter. In size and number ot cusps the first few laterals resemble the central tooth ; in the extreme marginals the cusps often become irregular or evanescent. As a rule, the teeth are set squarely in the rows, with the exception of the extreme marginals, which tend to slope away on either side. In some Helicidae there is a slight approxi- mation to the Zonitidae i in the elongation of the first marginals. The above is the type of radula occurring in the great family Helicidae, which includes not only Helix proper, with several thousand species, but also Arion, Bulimus, Ariolimax, and other genera. The jaw is almost always strongly transversely ribbed. In the Orthalicidae (Fig. 140, C) the teeth of the radula, instead of being in straight rows, slope back at an angle of about 45 degrees from the central tooth. The central and laterals are very similar, with an obtuse cusp on rather a long stem; the marginals become bicuspid. In the Bulimulidae, which include the important genera Placostylus, Amphidromus, Partula, Amphibulimus, and all the groups of South American Bulimulus, the jaw is very charac- teristic, being thin, arched, and denticulated at the edges, as if _ formed of numerous narrow folds overlapping one another. The radula is like that of the Helicidae, but the inner cusp of the laterals is usually lengthened and incurved. In Partula the sep- aration between laterals and marginals is very strongly marked. The remaining families of Pulmonata must be more briefly described. In the Cylindrellidae there are three distinct types of radula: (a) Central tooth a narrow plate, laterals all very curiously incurved with a blunt cusp, no marginals (Fig. 140, D); (6) radula long and narrow, central tooth as in (a), two laterals, and about eight small marginals; (¢) much more heli- cidan in type, central and laterals obtusely unicuspid, marginals quite helicidan. Type (c) is restricted to Central America, types (a) and (0) are West Indian. Pupidae: Radula long and narrow; teeth of the helicidan type, centrals and laterals tricuspid on a quadrate base, mar- ginals very small, cusps irregular and evanescent. This type 234 RADULA OF PULMONATA CHAP, includes Anostoma, Odontostomus, Buliminus, Vertigo, Strophia, Holospira, Clausilia, and Balea. Stenogyridae, including Achatina, Stenogyra, and all its sub- genera: Central tooth small and narrow, laterals much larger, tricuspid, central cusp long, marginals similar, but smaller. Achatinellidae: Two types occur; (a) teeth in very oblique rows, central, laterals, and marginals all of the same type, base narrow, head rather broad, with numerous small denticles (Achatinella proper, with Auriculella and Tornatellina, Fig. Fia. 140.— Portions of the radula of A, Hyalinia nitidula Drap., Yorkshire, with central tooth, first lateral, and a marginal very highly magnified; B, Helix pomatia L., Kent, showing central tooth, laterals, and one extreme marginal, the two former also highly magnified; C, Orthalicus undatus Brug., Trinidad, with three laterals highly magnified; D, Cylindrella rosea Pfr., Jamaica, central tooth and laterals, the same very highly magnified; E, Achatinella vulpina Feér., Oahu, central tooth (c) and laterals, the same highly magnified. 140, E); (2) central tooth small and narrow, laterals bicuspid, marginals as in Helix (Amastra and Carelia). Succinetdae: Central and laterals helicidan, bi- or tricuspid on a quadrate plate, marginals denticulate on a narrow base; jaw with an accessory oblong plate. Janellidae : Central tooth very small, laterals and marginals like Achatinellidae (a). Vaginulidae: Central, laterals, and marginals unicuspid throughout, on same plan. Onchidiidae: Rows oblique at the centre, straight near the VIII RADULA OF PULMONATA 235 edges; central strong, tricuspid; laterals and marginals very long, falciform, arched, unicuspid. Auriculidae: Teeth very small; central narrow, tricuspid on rather a broad base; laterals and marginals obscurely tricuspid on a base like Succinea. Limnaeidae: Jaw composed of one upper and two lateral pieces; central and lateral teeth resembling those of Helicidae ; marginals much pectinated and serriform (Fig. 141, A). In Fic. 141. — Portions of the radula of A, Limnaea stagnalis L., with the central tooth and two first laterals, and two of the marginals, very highly magnified; B, Ancylus fluviatilis Mill., with two of the marginals very highly magnified ; C, Physa fontinalis L., with cen- tra] tooth and two of the marginals very highiy magnified. Ancylus proper the teeth are of a very different type, base narrow, head rather blunt, with no sharp cusps, teeth similar throughout, except that the marginals become somewhat pec- tinated (Fig. 141, B); another type more resembles Limnaea. Physidae: Jaw simple, but with a fibrous growth at its upper edge, which may represent an accessory plate; radula with very oblique rows, central tooth denticulate, laterals and 236 RADULA OF SCAPHOPODA AND CEPHALOPODA CHAP. marginals serriform, comb-like, with a wing-like appendage at the superior outer edge (Fig. 141, C). Chilinidae: Central tooth small, cusped on an excavated triangular base, marginals five-cusped, with a projection as in Physa, laterals comb-like, serrations not deep. Amphibolidae: Central tooth five-cusped on a broad base, central cusp very large; two laterals only, the first very small, thorn-like, the second like the central tooth, but three-cusped ; laterals simple, sabre-shaped. Scaphopoda. — In the single family (Dentaliidae) the radula is large, and quite unlike that of any other group. The central tooth is a simple broad plate; the single lateral is strong, arched, and slightly cusped; the marginal a very large quadrangular plate, quite simple; formula, 1.1.1.1.1 (Fig. 133, B). Cephalopoda. — The radula of the Cephalopoda presents no special feature of interest. Perhaps the most remarkable fact about it is its singular uniformity of structure throughout a large number of genera. It is always very small, as compared with the size of the animal, most of the work being done by the powerful jaws, while the digestive powers of the stomach are very considerable. The general type of structure is a central tooth, a very few laterals, and an occasional marginal or two ; teeth of very uniform size and shape throughout. In the Dibranchiata, marginals are entirely absent, their place being always taken, in the Octopoda, by an accessory plate of varying shape and size. This plate is generally absent in the Decapoda. The central tooth is, in the Octopoda, very strong and characteristic; in Hledone and Octopus it is five-cusped, central cusp strong; in Argonauta unicuspid, in Z'remoctopus tricuspid. The laterals are always three in number, the in- nermost lateral having a tendency to assume the form of the central. In Sepia the two inner laterals are exact reproductions of Fra. 142. — Portion of the radula of Octopus tetra- the central tooth: in Ele- cirrhus D.Ch., Naples. x 20. ; done, Sepiola, Loligo, and Sepia, the third lateral is falciform and much the largest. In Nautilus, the only living representative of the Tetra- VIII SALIVARY GLANDS 237 branchiata, there are two sickle-shaped marginals on each side, each of which has a small accessory plate at the base. The two laterals and the central tooth are small, very similar to one another, unicuspid on a square base. Salivary glands are found in most Glossophora. They occur in one or two pairs on each side of the pharynx and oesophagus, the duct usually leading forwards and opening into the anterior part of the pharynx (see Figs. 148, 144). They are exception- ally large in the carnivorous Gasteropoda. In certain genera, e.g. Murex, Dolium, Cassis, Pleurobranchus, the secretions of these glands are found to contain a considerable proportion (sometimes as much as 4:25 per cent of free sulphuric acid. This fact was Fia. 143. — Alimentary canal of Helix aspersa L.: a, anus; 0.d, b.d’, right and left biliary ducts; 6.m, buccal mass; c, crop; h.g, hermaphrodite gland; 7, intestine; 4.0, opening of same from stomach (pyloric orifice) ; /, /', right and left lobes of liver; m, mouth; oe, oesophagus; 7, rectum; s.d, salivary duct; s.g, salivary gland; st, stomach; ¢, left tentacle. (After Howes and Marshall, slightly modified.) first noticed by Troschel, who, while handling a Doliwm galea at Messina, saw the creature spit a jet of saliva upon a marble slab, which immediately produced a brisk effervescence. A number of the genera thus provided bore through the shells of other Mollusca and of Echinoderms, to prey upon their soft tissues, and it is possible that the acid assists in the piercing of the shell by converting the hard carbonate of lime into sulphate of lime, which can easily be removed by the action of the radula.t In the majority of the Cephalopoda there are two pairs of salivary glands, one lying on each side of the mouth, the other on the middle of the oesophagus. 3. The Oesophagus.— That part of the alimentary canal which 1 Semon, Biol. Centralbl. ix. p. 80. 238 THE OESOPHAGUS CHAP, lies between the pharynx and the stomach Cn Pelecypoda between the mouth and stomach) is known as the oesophagus. Its exact limits are not easy to define, since in many cases the tube widens so gradually, while the muscular structure of its walls changes so slowly that it is difficult to say where oesopha- gus ends and stomach begins. As a rule, the oesophagus is fairly p.ae See a =e Fig. 145.— Gizzard of Scaphander lignarius L.: A, showing posi- tion with regard to oesophagus (oe) and intestine (), the latter being full of comminuted frag- ments of food; p, left plate; p', right plate; p.ac, accessory plate; B, the plates as seen from the front, with the envel- oping membranes removed, let- tering asin A. Natural size. Fia. 144. — Alimentary canal, etc., of Sepia officinalis L.: a, anus; b.d, one of the biliary ducts; b.m, buccal mass; c, coecum; 2, ink-sac; 7.d, duct of same; 7, jaws; J.l/, lobes Fic. 146.—-Section of the stomach of of the liver; oe, oesophagus ; Melongena, showing the gastric plates p, pancreatic coeca; 7, rec- (g-p, g-p,) for the trituration of food; tum; s.g, salivary glands; st, b.d,. biliary duct; g.g, genital gland; stomach. (From a specimen i, intestine; 7, liver; oe, oesophagus ; in the British Museum.) st, stomach. (After Vanstone.) simple in structure, and consists of a straight and narrow tube. In the Pulmonata and Opisthobranchiata it often widens out into a ‘crop,’ which appears to serve the purpose of retaining a quantity of masticated food before it passes on to the stomach. In Octopus and Patella the crop takes the form of a lobular coecum. In the carnivorous Mollusca the oesophagus becomes complicated by the existence of a varying number of glands, by a a i i tl VIII THE STOMACH AND ITS APPENDAGES 239 the action of which digestion appears to begin in some cases - before the food reaches the stomach proper. 4. The Stomach. — At the posterior end of the oesophagus lies the muscular pouch known as the stomach, in which the digestion of the food is principally performed. This organ may be, as in Inmax, no more than a dilatation of the alimentary canal, or it may, as is usually the case, take the form of a well-marked bag or pocket. The two orifices of the stomach are not always situated at opposite ends; when the stomach itself is a simple enlargement of the wall of one side of the alimentary canal, the cardiac or entering orifice often becomes approximated to the orifice of exit (pyloric orifice). The walls of the stomach itself are usually thickened and strengthened by constrictor muscles. In some Nudibranchs (Sceyllaea, Bornella) they are lined on the inside with chitinous teeth. In Cyclostoma, and some Bithynia, Strombus, and Trochus there is a free chitinous stylet within the stomach.!. In Melon- gena (Hig. 146) the posterior end of the oesophagus is provided with a number of hard plate-like ridges, while the stomach is lined with a double row of cuticular knobs, which are movable on their bases of attachment, and serve the purpose of triturating food.2 Aplysia has several hard plates, set with knobs and spines, and similar organs occur in the Pteropoda. But the most formid- able organ for the crushing of food is possessed by the Bullidae, and particularly by Scaphander (Fig. 145). Here there is a strong gizzard, consisting of several plates connected by powerful cartilages, which crush the shells, which are swallowed whole. Into the stomach, or into the adjacent portions of the diges- tive tract, open the ducts which connect with the so-called liver. The functions of this important organ have not yet been thoroughly worked out. The liver is a lobe-shaped gland of a brown-gray or light red colour, which in the spirally-shelled families usually occupies the greater part of the spire. In the Cephalopoda, the two ducts of the liver are covered by append- ages which are usually known as the pancreatic coeca; the bil- lary duct, instead of leading directly into the stomach, passes 1 According to Moquin-Tandon (Moll. de France, i. p. 44) this process in Bithynia is attached by one end to the wall of the stomach. Vivipara, with two jaw pieces, does not possess this stylet ; Bithynia, which does possess it, has no jaw. 2 J. H. Vanstone, Journ. Linn. Soc. xxiv. p. 369. 240 THE LIVER AND HYALINE STYLET CHAP. into a very large coecum (see Fig. 144) or expansion of the same, which serves as a reservoir for the biliary secretions. At the point of connexion between the coecum and stomach is found a valve, which opens for the issue of the biliary products into the stomach, but closes against the entry of food into the coecum. In most Gasteropoda the liver consists of two distinct lobes, between which are embedded the stomach and part of the intestine. In many Nudibranchiata the liver becomes ‘ diffused ’ or broken up into a number of small diverticula or glands con- necting with the stomach and intestine. The so-called cerata or dorsal lobes in the Aeolididae are in effect an external liver, the removal of which to the outside of the body gives the creature additional stomach-room. The Hyaline Stylet. —In the great majority of bivalves the intestine is provided with a blind sac, or coecum of varying length. Within this is usually lodged a long cylindrical body known as the hyaline or crystalline stylet. In a well-developed Mytilus edulis it is over an inch in length, and in Mya arenaria between two and three inches. The bladder-like skin of the stylet, as well as its gelatinoid substance, are perfectly trans- parent. In the Unionidae there is no blind sac, and the stylet, when present, is in the intestine itself. It is said to be present or absent indifferently in certain species. The actual function performed by the hyaline stylet is at present a matter of conjecture. MHaseloff’s experiments on Mytilus edulis tend to confirm the suggestion of Mobius, that the structure represents a reserve of food material, not specially secreted, but a chemical modification of surplus food. He found that under natural conditions it was constantly present, but that specimens which were starved lost it in a few days, the more complete the starvation the more thorough being the loss; it reappeared when they were fed again. Schulze, on the other hand, believes that it serves, in combination with mucus secreted by the stomach, to protect the intestine against laceration by sharp particles introduced with the food. W. Clark found that in Pholas the stylet is connected with a light yellow corneous plate, and imagined therefore that it acts as a sort of spring to work the plate in order to comminute the food, the two together performing somewhat the function of a gizzard. 1 Biol. Centralbl. vii. p. 683; SB. Ges. Nat. Fr. 1890, p. 42; Mag. Nat. Hist. (2) v. 1850, p. 14. VIII THE INTESTINE 241 5. and 6. The Intestine, Rectum, and Anus. — The intestine, the wider anal end of which is called the rectum, almost invari- ably makes a bend forward on leaving the stomach. is the case in the Cephalopoda, Scaphopoda, and the great majority of Gasteropoda. The exceptions are the bilaterally symmetrical Amphineura, in which the anus is terminal, and many Opisthobranchiata, in which it is sometimes lateral (Fig. 68, p. 159), some- times dorsal (Fig. 67). The intestine is usually short in carnivorous genera, but long and more or less convoluted in those which are phytophagous. In all cases where a branchial or pulmonary cavity exists, the anus is situated within it, and thus varies its position according to the position of the breathing organ. Thus in Helix it is far forward on the right side, in Testacella, Vagi- nula, and Onchidium almost terminal, in Patella at the back of the neck, slightly to the right side (Fig. 64, p. 157). In the rhipidoglossate section of the Dio- tocardia (Trochus, Haliotis, etc.) the rectum passes through the ventricle of the heart, a fact which, taken in conjunction with others, is evidence of their relationship to the , Pelecypoda. In nearly all Pelecypoda the intestine is very long and convoluted, being sometimes doubled forward over the mouth. Towards its terminal part it traverses the ventricle of the heart, except in Ostrea, Anomia, Teredo, and afew more. The anus is always at the posterior end of the animal, adjacent to and slightly above the adductor muscle. Anal glands, which open into the rectum close to the anus, are present in some Proso- branchiata, e.g. Murex, Purpura. In the This BiG.) 147, — Ink =Sac-. of Sepia, showing its re- lation to the rectum: a, anus; d, duct of sac; 7.g, ink-gland; i.r, portion of the sac which serves as a re- servoir for the ink; 0, orifice of ink-gland ; 7, rectum ; sp, double set of sphincter muscles controlling upper end of duct. (Modified from Girod.) Cephalopoda the anal gland becomes of considerable size and importance, and is generally a as the ink-sac (Fig. 147); 5 R VOL. Ill 1 242 THE KIDNEYS ; CHAP. it occurs in all known living genera, except Nautilus. The ink- sac consists of a large bag generally divided into two portions, in one of which the colouring matter is secreted, while the other acts as a reservoir for its storage. A long tube connects the bag with the end of the rectum, the mouth of the tube being controlled, in Sepia, by a double set of sphincter muscles. The Kidneys The kidneys, nephridia,! renal or excretory organs, consist typically of two symmetrical glands, placed on the dorsal side of the body in close connexion with the pericardium. Each kidney opens on the one hand into the mantle cavity, close to the anus (see Fig. 64, p. 157), and on the other, into the peri- cardium. The venous blood returning from the body passes through the vascular walls of the kidneys, which are largely formed of cells containing uric acid. The blood thus parts with its impurities before it reaches the breathing organs. The kidneys are paired in all cases where the branchiae are paired, and where the heart has two auricles, z.e. in the Amphi- neura, the Diotocardia (with the exception of the Neritidae), the Pelecypoda, and all Cephalopoda except Nautilus, which has four branchiae, four auricles, and four kidneys. In other Gasteropoda only one kidney survives, corresponding to the left kidney of Zygobranchiate Gasteropods. Besides their use as excretory organs the kidneys, in certain groups of the Mollusca, stand in very close relation to the geni- tal glands. In some of the Amphineura the generative products, instead of possessing a separate external orifice of their own, pass from the genital gland into the pericardium and so out through the kidneys (see Fig. 61 C, D, p. 154). In the Dioto- cardia it is the right kidney alone which serves, besides its excretory functions, as a duct for the emission of the generative products, the left kidney being at the same time greatly reduced in size. Thus in Patella the left nephridium is small, the right being much larger; both function as excretory organs, but the right serves as a mode of conveyance for the seminal products as well. In certain Pelecypoda (e.g. Yoldia, Avicula, Modiola, Pecten, Spondylus) the genital glands communicate directly, 1 pede 's, kidney. H | . VIII AUTHORITIES | 243 ss 2 ee ee ee and with a similar object, with the renal pouch on the same side of the body, but in the majority of cases the orifices are distinct. _ The following memoirs will be found useful for further study of this portion of the subject : — D. Barfurth, Ueber den Bau und die Thiatigkeit der Gasteropodenleber : Arch. Mikr. Anat. xxii. (1883), pp. 473-524. Th. Behme, Beitrige zur Anatomie und Entwickelung gsgeschichte des Hone apparates der Lungenschnecken: Arch. Naturges. iv. (1889), pp. 1-28. R. Bergh, Semper’s Reisen im Archipelago der PP elpsetnes Nudibran- chiata: Theil 11. Band ii. (1870-78), Band iii. (1880-1892). W. G. Binney, Terrestrial Air-breathing Mollusks of the United States: Bull. Mus. C. Z. Harv. iv. (1878), 450 pp. 3 On the Jaw and Lingual Membrane of North American Terrestrial Pulmonata: Proc. Ac. Nat. Sc. Philad. (1875), pp. 140-243. i 2. Cunningham, The renal or gans (Nephridia) of Patella: Quart. Journ. Mier. Sc. xxiii. (1883), pp. 369-375. - ” Note on the structure and relations of the kidney in Aplysia: Mitth. Zool. Stat. Neap. iv. (1883), pp. 420-428. R. von Erlanger, On the paired Nephridia of Prosobranchs, etc.: Quart. Journ. Micr. Se. xxxili. (1892), pp. 587-623. H. Fischer, Recherches sur ]a Morphologie du Foie des Gastéropodes: Bull. Scient. France Belg. xxiv. (1892), pp. 260-346. C. Grobben, Morphologische Studien tiber den Harn- und Geschlechtsapparat, sowie die Leibeshohle, der Cephalopoden: Arb. Zool. Inst. Wien, v. (1884), pp. 179-252. 5 Die Pericardialdriise der Gasteropoden: ibid. ix. (1890), pp. 35-56. B. Haller, Beitrige zur Kenntniss der Niere der Prosobranchier: Morph. Jahrb. xi. (1885), pp. 1-53. A. Hancock, On the structure and homologies of the renal organ in the Nudibranchiate Mollusca: Trans. Linn. Soc. xxiv. (1864), pp. 511-530, A. Kohler, Microchemische Untersuchung der Schneckenzungen: Zeits. Gesamm. Naturw. viii. (1856), pp. 106-112. Ad. Oswald, Der Riisselapparat der Prosobranchier: Jena. Zeits. ‘Naturw. N.F. xxi. (1893), pp. 114-162. _R. Perrier, Recherches sur l’anatomie et Vhistologie du rein des Gastéro- podes prosobranches: Ann. Sc. Nat. Zool. (7), vill. (1889), pp. 61-315. C. Semper, Reisen im Archipelago der Philippinen; Land Pulmonata: , Theit ii. Band iii. (1870-77). C. Troschel, Das Gebiss der Schnecken: Berlin, 1856-1892. W. G. Vigelius, Ueber das Excretionssystem der Cephalopoden: Niederl. Arch. Zool. v. (1880), pp. 115-184. CHAPTER IX & THE SHELL, ITS FORM, COMPOSITION AND GROWTH — DESIG- NATION OF ITS VARIOUS PARTS THE popular names of ‘shells,’ ‘shell-fish,’ and the like, as commonly applied to the Mollusca, the intrinsic beauty and grace of the shells themselves, resulting in the passion for their collection, their durability and ease of preservation, as compared with the non-testaceous portion, —all these considerations tend to unduly exalt the value of the shell as part of the organism as a whole, and to obscure the truth that the shell is by no means the most important of the organs. At the same time it must not be forgotten that the old systems of classification, which were based almost entirely on indications drawn from the shell alone, have been strangely little disturbed by the new principles of arrangement, which depend mainly on structural points in the animal. This fact only tends to emphasise the truth that the shell and animal are in the closest possible connexion, and that the shell is a liy- ing part of the organism, and is equally sensitive to external influences. A striking instance of the comparative valuelessness of the shell alone as a primary basis of classification is furnished by the large number of cases in which a limpet-shaped shell is assumed by genera widely removed from one another in cardinal points of organisation. This form of shell occurs in the com- mon limpet (Patellidae), in Ancylus (Limnaeidae), Hemitoma (Fissurellidae), Coceulina (close to Trochidae), Umbrella and Siphonaria (Opisthobranchiata), while in many other cases the limpet form is nearly approached. Roughly speaking, about three-quarters of the known Mol- lusca, recent and fossil, possess a univalve, and about one-fifth 244 CHAP. IX POSITION OF THE SHELL 245 a bivalve shell. In Pholas, and in some species of Thracia, there is a small accessory hinge plate; in the Polyplacophora, or Chitons, the shell consists of eight plates (see Fig. 2, p. 8), usually overlapping. A certain proportion of the Mollusca have no shell at all. In many of these cases the shell has been present in the larva, but is lost in the adult. The shell may be (1) eternal, as in the great majority of both univalves and bivalves. (2) Partly external, partly internal; e.g. Homalonyx, Hem- Fic. 148. — Aplustrum aplustre Fic. 149. — Sigaretus laeviga- L. Mauritius, showing the * tus Lam., showing shell partly internal shell (S) ; F, partially immersed in the foot; LL, cephalic lappets; foot ; F, anterior prolonga- TT, double set of tentacles. tion of the foot. (After (After Quoy and Gaimard.) Souleyet.) phillia, some of the Naticidae, Scutum, Acera, Aplustrum (Figs. 148 and 149). (8) Internal; e.g. Philine, Gastropteron, Pleurobranchus, Aplysia, Iimaz, Arion, Hyalimaz, Parmacella, Lamellaria, Cryptochiton, and, among bivalves, Chlamydoconcha. (4) Absent ; e.g. all Nudibranchiata and Aplacophora, many Cephalopoda, a few land Mollusca, e.g. all Onchidtidae, Philomycus, and Vaginula. The Univalve Shell. — In univalve Mollusca the normal form of the shell is an elongated cone twisted into a spiral form round an axis, the spiral ascending to the left. Probably the original form of the shell was a simple cone, which covered the vital parts like a tent. As these parts tended to increase in size, their 246 VARIOUS FORMS OF THE SPIRAL |S eae position on the dorsal side of the animal caused them gradually to fall over, drawing the shell with them. The result of these two forces combined, the increasing size of the visceral hump, and its tendency to pull the shell over with it, probably resulted in the conversion of the conical into the spiral shell, which gradually came to envelop the whole animal. Where the visceral hump, instead of increasing in size, became flattened, the conical shape of the shell may have been modified into a simple elliptical plate (e.e. Lemar), the nucleus representing the apex of the cone. In extreme cases even this plate dwindles to a few calcareous granules, or disappears altogether (Arion, ~ Vaginula). Varieties of the Spiral. — Almost every conceivable modifi- Fig. 150. — Examples of shells with A, a flattened spire (Polygyratia) ; B, a globose spire (Naé- ica) ; C, a greatly produced spire (Terebra). cation of the spiral occurs, from the type represented by Gena, Haliotis, Sigaretus, and Lamellaria, in which the spire is practi- cally confined to the few apical whorls, with the body-whorl inordinately large in proportion, to a multispiral form like Terebra, with about twenty whorls, very gradually increasing in size. As a rule, the spire is more or less obliquely coiled round the axis, each whorl being partially covered, and therefore hidden by, its immediate Successor, while the size of the whorls, and therefore the diameter of the spire as a whole, increases somewhat rapidly. The effect of this is to produce the elevated spire, the shell of six to ten whorls, and the wide aperture, of the normal type of mollusc, the whelk, snail, peri- winkle, ete. IX VARIOUS FORMS OF THE SPIRAL 247 Sometimes, however, the coil of the whorls, instead of being oblique, tends to become horizontal to the axis, and thus we have another series of gradations of form, from the excessively produced spire of Terebra to the flattened disc of Planorbis, | Polygyratia, Huomphalus, and Ammonites. The shell of many species of Conus practically belongs to the latter type, each whorl folding so closely over its predecessor that the spiral nature of the shell is not perceived until it is looked at at right angles to the spire. In some cases the regularly spiral form is kept, but the i —_— whorls are completely disconnected ; e.g. some Scalaria, Spirula; / ; 1 : 4 | — jv ¥ ' a J } LAlAt. Fic. 151.— Examples of shells Fic. 152.—Example of a shell _ , jf , f a ga with disconnected whorls; whose apical whorls alone are ‘ A, Cyathopoma cornu Mf., coiled, and the remainder pro- P im Ar mA Philippines; B, Cylindrella duced in a regular curve. acl. i hystrix Wright, Cuba. (Both (Cyclosurus Mariet Morel., s A x 4.) Mayotte.) f ‘ Py - ; ry . . " Os among fossil Cephalopoda, Gyroceras, Crioceras, and Ancyloceras; tt and, among recent land Mollusca, Cylindrella hystrix and Cyatho-;, \- ) , | poma cornu (Fig.151). Sometimes only the last whorl becomes || | . : . . j \ disconnected from the others, as in Rhiostoma (see Fig. 180, p. 266), Vx yet} Teinostoma, and in the fossil Ophidioceras and Macroscaphites. , ey Sometimes, again, not more than one or two whorls at the apex — are spirally coiled, and the rest of the shell is simply produced or/ coiledin anexceedingly irregular manner, e.g. Cyclosurus, Lituites, Orygoceras, Siliquaria (Fig. 153), Vermetus. In Coecum (Fig. 170, p. 260) the spiral part is entirely lost, and the shell becomes simply a cylinder. Ina few cases the last whorl is coiled irregu- larly backwards, and is brought up to the apex, so that the animal in crawling must carry the shell with the spire downwards, as in 248 FORMS OF THE SPIRAL CHAP. Anostoma (Fig. 154), Opisthostoma (Fig. 208, p. 309), Stropho- stoma, and Hypselostoma (Fig. 202 A, p. 302). Some genera of the Capulidae, in which the shell is of a broadly conical form or with scarcely any spire, develop an internal plate or process which serves the purpose of keeping the Fia. 153.— SiliquariaanguinaLam.,show- FieG.154.— Anostoma globulosum Lam., ing scalariform coil of upper whorls and Brazil. (After P. Fischer.) irregular extension of the lower. animal within the shell, and does the work of astrong attachment muscle. In Mitrularia this process takes the form of a raised horseshoe; in Crucibulum it is cup-shaped, with the edge free all round; in Galerus, Hrgaea, Crepipatella, and Trochita we get a Fia. 155.— Various forms of the internal plate in Capulidae: A, Calyptraea (Mitru- laria) equestris Lam., E. Indies; B, Crucibulum scutellatum Gray, Panama; C, Ergaea plana Ad., and Reeve, Japan; D, Galerus chinensis L., Britain; E, Crepi- patella dilatata Lam., Callao; F, Trochita maculata Quoy, N. Zealand; G, Crepi- dula fornicata Lam., N. America. series of changes, in which the edge of the cup adheres to the interior of the shell, and then gradually flattens into a plate. In Crepidula proper this plate becomes a regular partition, covering a considerable portion of the interior (Fig. 155 G). Hipponyx secretes a thin calcareous plate on the ventral surface of the foot, Ix SINISTRAL SHELLS 249 which intervenes like an operculum between the animal and the substance to which it adheres. Sinistral, or Left-handed Shells. — The vast majority of uni- valve spiral shells are normally deztral, i.e. when held spire uppermost, with the aperture towards the observer, the aperture is to the right of the axis of the spire. If we imagine such a shell to be a spiral staircase, as we ascended it we should always have the axis of the spire to our left. Sinistral or ‘ reversed ’ forms are not alto- gether uncommon, and may be grouped under four classes : — (1) Cases in which the genus is normally sinistral; (2) cases in which the genus is normally deztral, but certain species are d normally sinistral; (3) cases in which the gy, 156.— Fulgur per- shell is indifferently dextral or sinistral; verswm L., Florida. x7. (4) cases in which both genus and species are normally dextral, and a sinistral form is an abnormal monstrosity. In all cases of sinistral monstrosity, and all in which a sinistral and dextral form are interchangeable (sections 3 and 4 above), the position of the apertures of the internal organs appears to be relatively affected, z.e. the body is sinistral, as well as the shell. This has been proved to be the case in all specimens hitherto examined, and may therefore be assumed for the rest. The same uniformity, however, does not hold good in all cases for genera and species normally sinistral (sections 1 and 2). Asarule, the QOUE Fic. 157.— Illustration of the gradation of forms in Ampullaria between a dextral (A) and an ultra-dextral species (F). anal and genital apertures are, in these instances also, to the left, but notalways. In Spirialis, Limacina, Meladomus, and Lanistes the shell is sinistral, but the animal is dextral. This apparent anomaly has been most ingeniously explained by Simroth, Von 250 ULTRA-DEXTRAL AND ULTRA-SINISTRAL SHELLS CHAP, Ihering, and Pelseneer. The shell, in all these cases, is not really sinistral, but wltra-deztral. Imagine the whorls of a dextral species capable of being flattened, as in a Planorbis, and continue the process, still pushing, as it were, the spire down- wards until it occupies the place of the original umbilicus, becoming turned completely ‘inside out,’ and we have the whole explanation of these puzzling forms. The animal remains dextral, the shell has become sinistral. A convincing proof of the truth of this is furnished by the operculum. It is well known that the twist of the operculum varies with that of the shell; when the shell is dextral, the operculum is sinistral, with its nucleus near the columella, and vice versd. In these ultra- dextral shells, however, where it is simply the method of the enrolment of the spire that comes in question, and not the formation of the whorls themselves, the operculum remains sinistral on the apparently sinistral shell. The reverse case to this, when the shell is dextral but the orifices sinistral, is instanced by the two fresh-water genera Pompholyx (from N. America), and Choanomphalus (. Baikal). A similar transition in the enrolment of the whorls may be confidently assumed to have taken place, and the shells are styled wltra-sinistral. Yet another variation remains, in which the embryonic form is sinistral, but the adult shell dextral, the former remaining across the nucleus of the spire. This is the case with Qdos- tomia, Hulimella, Turbonilla, and Mathilda, all belonging to the Prosobranchiata, with Actaeon, Tornatina, and Actaeonina among the Opisthobranchs, and Melampus alone among Pulmonates. Monstrosities of the Shell.— Abnormal growths of the shell constantly occur, some of them being scarcely noticeable, except by a practised eye, others of a more serious nature, involving an entire change in the normal aspect of the creature. Scalariform monstrosities are occasionally met with, especially in Helix and Planorbis, when the whorls become unnaturally elevated, and sometimes quite disjoined from one another; carinated monstrosities develop a keel on a whorl usually smooth ; acuminated monstrosities have the spire produced to an extreme length (Fig. 158); s¢nzstral monstrosities (see above) have the spire reversed: dwarfs and giants, as in our own race, are occa- sionally noticed among a crowd of individuals. 1x MONSTROSITIES OF THE SHELL 251 More serious forms of monstrosity are those which occur in individual cases. Mr. 8. P. Woodward once observed! a speci- men of an adult Helix aspersa with a second, half-grown indi- vidual fixed to its spire, and partly embedded in the suture of the body whorl. The younger snail had died during its first hibernation, as was shown by the epiphragm remaining in the aperture, and its neighbour, not being able to get free of the incubus, partially enveloped it in the course of its growth. In the British Museum two Littorina littorea have become entan- eled in a somewhat similar way (Fig. 160 B), possibly as a Fic. 158. — Monstrosities of Neptunea an- Fig. 159. —Monstrosities of Littorina tiqua L., and Buccinum undatum L., rudis Mat, The Fleet, Weymouth. with a greatly produced spire (from (After Sykes.) specimens in the Brit. Mus.). result of embryonic fusion. Double apertures are not uncom- mon?in the more produced land-shells, such as Cylindrella and Clausilia (Fig. 160 A). In the Pickering collection was a FHlelix hortensis which had crawled into a nutshell when young, and, growing too large to escape, had to carry about this de- cidedly extra shell to the end of its days. A monstrosity of the cornucopia form, in which the whorls are uncoiled almost throughout, is of exceedingly rare occurrence (Fig. 161). Some decades ago ingenious Frenchmen amused themselves by creating artificial monstrosities. H. aspersa was taken from its shell, by carefully breaking it away, and then introduced into another shell of similar size (4. nemoralis, vermiculata, or 1 Ann. Mag. Nat. Hist. (2) xvi. p. 298. 2 See, for instance, Quart. Journ. Conch. i. p. 340 (Cyl. Raveni): Jahrb. Deut. Malak. Gesell. 1879, p. 98 (Clausilia dubia). 252 \ CHEMICAL COMPOSITION OF THE SHELL CHAP. pisana). At the end of several days attachment to the colu- mella took place, and then growth began, the new shell becom- ing soldered to the old, and the spiral part of the animal being protected by a thin calcareous envelope. A growth of from one to two whorls took place under these conditions. The indi- viduals so treated were always sordid and lethargic, but they bred, and naturally produced a normal aspersa offspring! In Fic. 160.— Monstrosities with two Fic. 161.— Cornucopia- apertures: A, Cylindrella ag- shaped monstrosity nesiana C. B. Ad., Jamaica; B, of Helix aspersa, Littorina littorea (from specimens from Ilfracombe. in the British Museum). (British Museum.) the British Museum there is a specimen of one of these artificial unions of a Helix with the shell of a Zamnaea stagnalis. Composition of the Shell. — The shell is mainly composed of pure carbonate of lime, with a very slight proportion of phos- phate of lime, and an organic base allied to chitin, known as conchiolin. ‘The proportion of carbonate of lime is known to vary from about 99 p.c. in Strombus to about 89 p.c. in Turri- tella. Nearly 1 p.c. of phosphate of lime has been obtained from the shell of Helix nemoralis, and nearly 2 p.c. from that of Ostrea virginica. ‘The conchiolin forms a sort of membranous framework for the shell; it soon disappears in dead specimens, leaving the shell much more brittle than it was when alive. Carbonate of magnesia has also been detected, to the extent of 12 p.c. in Telescopium and :48 p.c. in Neptunea antiqua. A trace of silica has also occasionally been found. 1 Cailliaud, Journ. de Conchyl. vii. p. 2831; Gassies, tbid. p. 44. 1x CHEMICAL COMPOSITION OF THE SHELL 253 When the shell exhibits a crystalline formation, the carbonate of lime may take the form either of calezte or aragonite. The calcite crystals are rhombohedral, optically uniaxal, and cleave easily, while the aragonite cleave badly, belong to the rhombic system, and are harder and denser, and optically biaxal. Both classes of crystal may occur in the same shell. Two main views have been held with regard to the formation and structure of the shell— (1) that of Bowerbank and Car- penter, that the shell is an organic formation, growing by inter- stitial deposit, in the same manner as the teeth and bones of the higher animals; (2) that of Réaumur, Eisig, and most modern writers, that the shell is of the nature of an excretion, deposited like a cuticle on the outside of the skin, being formed simply of a number of calcareous particles held together by a kind of ‘animal glue.’ Leydig’s view is that the shell of the Mono- tocardia is a secretion of the epithelium, but. that in the -Pulmonata it originates within the skin itself, and afterwards becomes free.? According to Carpenter, when a fragment of any recent shell is decalcified by being placed in dilute acid, a definite ani- mal basis remains, often so fine as to be no more than a mem- branous film, but sometimes consisting of an aggregation of ‘cells’ with perfectly definite forms. He accordingly divides all shell structure into cellular and membranous, according to the characteristics of the animal basis. Cellular structure is comparatively rare; it occurs most notably in Pznna, where the shell is composed of a vast multitude of tolerably regular hex- agonal prisms (Fig. 162 B). Membranous structure comprises all forms of shell which do not present a cellular tissue. Car- penter held that the membrane itself was at one time a con- stituent part of the mantle of the mollusc, the carbonate of lime being secreted in minute ‘cells’ on its surface, and after- wards spreading over the subjacent membrane through the bursting of the cells. The iridescence of nacreous shells is due to a peculiar line- ation of their surface, which can be readily detected by a lens. According to Brewster, the iridescence is due to the alterna- tion of layers of granular carbonate of lime and of a very thin organic membrane, the layers very slightly undulating. Car- 1 Arch. Naturgesch. xlii. p. 209. 254 STRUCTURE OF THE SHELL CHAP. penter, on the other hand, holds that it depends upon the dis- position of a single membranous layer in folds or plaits, which he more or less obliquely to the general surface, so that their edges show as lines. The nacreous type of shell occurs largely among those Mollusca which, from other details in their organ- isation, are known to represent very ancient forms (e.g. Wueula, Avicula, Trigonia, Nautilus). It is also the least permanent, and thus in some strata we find that only casts of the nacreous shells remain, while those of different constitution are preserved entire. Porcellanous shells (of which the great majority of Gastero- poda are instances) usually consist of three layers, each of which is composed of a number of adjacent plates, like cards on edge. The inclination of the plates in the different layers varies, but that of the plates in the inner and outer layer is frequently the ——S—— — yg af Teg ag Fic. 162. — A, Section of shell of Unio: a, periostracal layer; 0, prismatic layer; c,~ nacreous layer. B, Horizontal section of shell of Pinna, showing the hexagonal prisms. same, thus if the plates are transverse in the middle stratum, they are longitudinal in the inner and outer strata, and, if longitudinal in the middle, they are transverse in the other two. Not uncommonly (Fig. 163 B) other layers occur. In bivalves the disposition and nature of the layers is much more varied. In Unio the periostracal or uppermost layer is very thin; beneath this is a prismatic layer of no great depth, while the whole remainder of the shell is nacreous (Fig. 162 A). Many bivalves show traces of tubular structure, while in the Veneridae the formation and character of the layers approaches closely to that of the Gasteropoda. Further details may be gathered from Carpenter’s researches.! 1 Dr, W. B. Carpenter, Rep. Brit. Ass. xiii. p. 71; xiv. p. 1; xvii. p. 98; J.S. Bowerbank, Trans. Micr. Soc. i. p. 123; Ehrenbaum, Zeit. wiss. Zool. xli. p. 1. 1X DEPOSITION AND FORMATION OF SHELL 255 Formation of Shell.!— The mantle margin is the principal agent in the deposition of shell. It is true that if the shell be fractured at any point, the hole will be repaired, thus showing that every part of the mantle is furnished with shell-depositing cells, but such new deposits are devoid of colour and of periostra- cum, and no observation seems to have been made with regard to the layers of which they are composed. As arule the mantle, except at its margin, only serves to thicken the innermost layer of shell. It is probable that the carbonate of lime, of which the shell is mainly composed, is separated from the blood by the epithelial cells of the mantle margin, and takes the crystalline or granular form as it hardens on exposure after deposition. The three layers of a porcellanous shell are deposited successively, and Fie. 163.— Sections of shells. A, Conus: a, outer layer; 6, middle prismatic layer, with obliquely intersecting laminae above and below; c¢, inner layer. B, Oliva: a, outer layer; 0b, layer of crossed and curved laminae; c, prismatic layer, suc- ceeded by layer of laminae at right angles to one another; d, inner layer. C, Cypraea: a, outer layer; b, middle layer; c, inner layer. the extreme.edge of the mouth, when shell is forming, will contain only one layer, the outermost; a little further in, two layers appear, and further still, three. The pigment cells which colour the surface are situated at the front edge of the mantle margin. Shelly matter is deposited, and probably secreted, not only by the mantle, but also in some genera by the foot. This is cer- tainly the case in Cymbium, Oliva, Ancillaria, Cassis, Distortio, and others, in several of which the foot is so large that the shell appears to be quite immersed in it.? 1 See also p. 258, 2 J, E. Gray, Phil. Trans. 1833, p. 774 f. , ‘ 256 SCULPTURE AND ORNAMENTATION CHAP. The deposition of shell is not continuous. Rest periods occur, during which the function is dormant; these periods are marked off on the edge of the shell, and are known as lines of growth. In some cases (Murex, Triton, Ranella), the rest period is marked by a decisive thickening of the lip, which persists on the surface of the shell as what is called a variz (see p. 263). The various details of sculpture on the exterior surface of the shell, the striae, ribs, nodules, imbrications, spines, and other forms of ornamentation are all the product of similar and corre- Fia. 165. — Neritina longi- spina Récl., Mauritius. (Operculum removed.) Fic. 164. — Murex tenuispina L., Ceylon. x 2. sponding irregularities in the mantle margin, and have all been originally situated at the edge of the lip. Spines, e.g. those of Murex and Pteroceras, are first formed as a hollow thorn, cleft down its lower side, and are afterwards filled in with solid matter as the mantle edge withdraws. What purpose is served by the extreme elaboration of these spiny processes in some cases, can hardly be considered as satisfactorily ascertained. Possibly they are a form of sculptural development which is, in Ix GROWTH OF THE SHELL 257 the main, protective, and secures to its owners immunity from the attacks of predatory fishes. ‘Attached’ genera (e.g. Chama, Spondylus) when living on smooth surfaces have a flat shell, but when affixed to coral and other uneven surfaces they become very irregular in shape. The sculpture of the base on which they rest is often reproduced in these ‘attached’ shells, not only on the lower, but also on the upper valve, the growing edge of which rests on the uneven surface of the base. Oysters attached to the branches of the mangrove frequently display a central convex rib, modelled on the shape of the branch, from which the plaits of sculpture radi- ate, while specimens fixed to the smooth trunk have no such rib. Crepidula, a genus which is in the habit of attaching itself to other shells, varies in sculpture according to that of its host. Sometimes the fact may be detected that a specimen has lived on a ribbed shell when young, and on a smooth one when old, or vice versd. A new genus was actually founded by Brown for a Capulus which had acquired ribs through adhesion to a Pecten. A specimen of Minnites giganteus in the British Museum must at one period of its growth have adhered toa surface on Fic. 166.— A specimen of Anomia which was aSerpula, the impression ¢Phippium L., Weymouth, taken : : : upon Pecten maximus, the sculp- merhieh is plainly reproduced on + ‘are of whichis reproduced. on the upper valve of the Hinnites.1 — ae upper valve of the ers, Growth of the Shell. — Noth- attached to the larger specimen. ing very definite is known with regard to the rate of growth of the shell in marine Mollusca. Under favourable conditions, however, certain species are known to increase very rapidly, especially if the food supply be abun- dant, and if there is no inconvenient crowding of individuals. Petit de la Saussaye mentions? the case of a ship which sailed from Marseilles for the west coast of Africa, after being fitted with an entirely new bottom. On arriving at its destination, the vessel spent 68 days in the Gambia River, and took 86 days on its homeward voyage. On being cleaned immediately on its 1J.E. Gray, Phil. Trans. 1833, p. 774 f. 2 Journ. de Conchyl. iv. p. 424. VOL. III S 258 GROWTH OF THE SHELL CHAP. return to Marseilles, an Avicula T8 mm. and an Ostrea 95 mm. long (both being species peculiar to W. Africa) were taken from its keel. ‘These specimens had therefore attained this growth in at most 154 days, for at the period of their first attachment they are known to be exceedingly minute. PP. Fischer relates} that in 1862 a buoy, newly cleaned and painted, was placed in the basin at Arcachon. In less than a year after, it was found to be covered with thousands of very large Mytilus edulis, 100 mm. x 48 mm., the ordinary size on the adjoining banks being only about 50 to 60 x 30 mm. Some observations have already been recorded (p. 40) on the growth of Helix aspersa. In the summer of 1858, which was very dry, especially in the south of France, the young Helices born that year were still very small in August. About the end of that month abundant rain came on, and in four or five days young H. variabilis, H. pisana, and H. aspersa, eating with- out cessation, as if to make up for lost time, grew more than a centimetre of shell. The lip of a young #. arbustorum has been observed to have grown, at the end of the first week in the season’s growth, 3 mm., at the end of the second week, 6:25 mm., the third, 11-5 mm., and the fourth 12-5 mm., with a finished lip.? Careful observation has shown that in the growth of the shell of Helix aspersa the periostracum is first produced ; it is covered with hyaline globules, 10-12 mm. in diameter, which persist even in the oldest shells. Calcareous matter is deposited on the internal face of the new periostracum, at some distance from the margin. It is secreted by a white zone or band of cells bound- ing the entire breadth of the mantle as applied to the peristome. Immediately behind the white zone are a series of pigment cells which not only give the shell its colour but complete the calcifi- cation of the shelly matter laid down by the white zone. When the animal has attained its full growth and the lip is finished off, the white band and the periostracum cells completely dis- appear, and only such cells persist as contribute to the internal thickening of the shell. Shell growth, in this species, is very rapid. Ifa portion of the pulmonary sac is laid bare, by remoy- ing a fragment of shell, at the end of 13 or 2 hours there may be detected a delicate organic membrane covering the hole, and strewn with crystals of carbonate of hme. This thickens with 1 Journ. de Conchyl. xii. p. 3. 2 T. Scott, Journ. of Conch., 1887, p. 280. Ix GROWLED OF THE SHELL 259 great rapidity, and soon fills up the hole with solid matter. For two consecutive months an animal, deprived of food, has been known to reproduce this membrane daily after its removal every morning.! Prof. Schiedt has found that oysters, if deprived of the right valve and exposed to the light, not only develop brown pigment over the whole exposed surface of mantle and branchiae, but actually succeed in part in reproducing the valve and hinge? Deposit of Additional Layers of Shell. — Mollusca possess the power of thickening the interior of the shell, by the deposit of successive layers. This is frequently done in self-defence against the attacks of boring Mollusca, sponges, and worms. Cases may often be noticed of Ostrea, Spondylus, and other sedentary molluscs, which, unable to escape the gradual assaults of their foes, have provided against them by the deposit of fresh shelly matter. A somewhat similar plan is adopted to provide against intrusion by way of the aperture. Pearls are, in many cases, the result of shell deposition upon the eggs or even the body of some intrusive parasite (Distoma, Filaria, etc.), and are, in some countries, artificially produced by the introduction of fragments of sand, metal, etc., into living : Unio and Anodonta. Little joss images Fic. 167.—A specimen of are made in India and China, the nacre Coen Pee nis on which is produced by thrusting them whieh a piece of grass inside living Unionidae. BO Geena A specimen of Helix rosacea, in the animal has protected British Museum, into whose shell a piece aan ea of grass somehow became introduced, has _—(Froma specimen in the partitioned it off by the formation of a P™tsh Museum.) sort of shelly tunnel extending throughout its entire length (Fig. 167). Absorption of Internal Portions.— Certain genera have the remarkable property of absorbing, when they become adult, the internal portions of the whorls and the greater part of the columellar axis. The effect of this is to make the shell, when the process is complete, no longer a spiral but a more or less produced cone, and it is found that in such cases the viscera of 1M. de Villepoix, Comptes Rendus, cxiii. p. 317. 2 Proc. Ac. Nat. Sc. Phil., 1892, p. 350. 260 ABSORPTION OF INTERNAL PARTS—DECOLLATION cnap. the spire lose their spiral form, and take the shape of the cavity in which they lie. Amongst the genera in which this singular proc- ess takes place are Nerita,! Olivella, and Cypraea amongst marine forms, and nearly the whole of the Auriculidae? (Fig. 168). Conus reduces the internal subdivisions of the spire to extreme thin- ness. It is noticeable that these genera are all of considerable thickness of shell, and it is per- haps the result of the whole energy of the animal being directed to the formation of its external protection that the internal walls of the spire become atrophied and eventually disappear. Decollation. —In certain genera, when the shell becomes adult, the animal ceases to occupy the upper whorls, which accordingly die and drop Fic. 168. — Auri- cula Judae Lam., showing the disappear- ance of the par- titions of the whorls, which are represented off, the orifice at the top having meanwhile been closed by a shelly deposit. Such shells are termed decollated. In some land genera decollation is the rule, e.g. in Cylindrella (Fig. 169), Hucalo- by dotted lines. y ; : - dium, and Rumina, as well as in many species of (After Fischer.) Fic. 169. — A, Decollated (adult) form, and B, perfect (young) form of Cylindrella nobilior Ad., Jamaica; the dotted line shows where decollation takes place. Fic. 170.— Development of Coecum: A, showing the gradual formation of septa; a, apex; ap, aperture; Ss, first septum; s's', second septum. (After de Folin.) B, Adult form of C. eburneum Ad., Panama. x 8. the brackish water genera, Truncatella, Cerithidea, and Quoyia. Stenogyra (Rumina) decollata, a common shell in the south of ! Mr. B. B. Woodward has recently pointed out (P. Z. S. 1892, p. 528) a very remarkable method of shell absorption and growth in Velates and certain other Neritidae. 2 The only exception appears to be Pedipes, while in Cassidula and Scarabus the absorption is partial (Crosse and Fischer, Journ. de Conch. xxx. p. 177 f.). IX DEVELOPMENT OF FISSURELLA, CYPRAEA, ETC. 261 Europe, has been noticed to bang its upper whorls violently against some hard substance, as if to get rid of them. Fie. 171. — Four stages in the growth of Fissurella, showing how the spire gradually disappears and the marginal slit becomes an apical hole, A, B, C, highly magni- fied, D, natural size. (After Boutan.) Special Points in the Growth of Certain Genera. —In the young of Coecum the apex is at first spiral, but as growth proceeds and the long tube begins to form, a septum is produced at the base of the apex, which soon drops off. Soon afterwards, a second septum forms.a little farther down, and a second piece drops off, leaving the shell in the normal cylindrical form of the adult (Fig. 170). The development of Fissurella is of extreme interest. In an early stage it possesses.a spiral shell, with a slit on the margin of the outer lip of the last whorl. As erowth advances, shelly matter is deposited on both margins, which results in the slit becoming a hole and the spire a mere cal- losity, until at last they appear to coalesce in the apex of the adult shell (F ig. iene The singular Fic. 172.— Three stages in the growth of Cypraea formations of Ma gilus and eee L. (From specimens taken at fthizochilus have already been described (pp. 75, 76). Cypraea, in the young stage, is a thin spiral shell with a conspicuous apex. As growth proceeds, 262 DEVELOPMENT .OF CYPRAEA, ANOMIA, ETC. CHAP. the surface of the whorls, which are nearly enveloped by two large lobes of the mantle, becomes overlaid with new layers of shelly matter, until eventually the spire becomes embedded, and ultimately disappears from view (Fig. 172). Patella, when young, has a nautiloid shell (see Fig. 45, p. 134), but it is a remarkable fact that we are entirely ignorant, in this commonest of molluscs, of the transition stages which convert the nautiloid into the familiar conical shell. The young shell of Pteroceras is deceptively unlike the adult, and is entirely devoid of the finger-like processes which are so characteristic of the genus (chap. xiv.). Among the bivalve Mollusca, Anomia in a young stage is not to be distinguished from Ostrea. Soon a small sinus appears on the ventral margin, which Cc gradually deepens and, as the shell grows round it, forms a hole for the byssus, eventually becoming fixed beneath the um- bones (see Fig. 173). In TZeredo the two valves of the shell proper, which is very small, become Fic. 173.— Development of the byssus- lodged oo long calcareous tube or the plug-hole in Anomia. (After Or cylinder, which is generally fae open at both ends (see chap. xvi.). In Aspergillum a somewhat similar cylinder is developed, but the valves are soldered to the tube, and form a part of it, the tube itself being furnished, at the anterior end, with a disc, which is perforated with holes like the rose of a watering-pot. In Clavagella the left valve alone becomes soldered to the tube, while the right valve is free within it (see chap. xvi.). stulana encloses the whole of its shell in a long tapering tube, which is not at any point adherent to the shell. Terms employed to denote various Parts of the Univalve Shell. — The apex is the extreme top of the spire, and generally consists of the embryonic shell, which may often be recognised by its entire want of sculpture. When the embryonic shell happens to be large, the apex is often mammillated, e.g. in Fusus, Neptunea, and some Turbinella; in the Pyramidellidae it is sinistral. The sutwre is the line of junction between any two successive Ix PARTS OF THE UNIVALVE SHELL 263 whorls. It may be deep, and even channelled, or very shallow, as in Fig. 150 B (p. 246). The spire is the whole series of whorls except the last or body whorl. A whorl is a single revolution of the spiral cone round the axis. The spire may be suwbulate (as in Terebra, Fig. 150 C), turret ed (Scalaria), depressed (Polygyratia, Fig. 150 A), -- spire - posterior canal (if present) outer lip columella ----- é “s mouth or aperture anterior canal Fic. 174. — Illustrating the technical terms applied to the various parts of a univalve shell. conical (Trochus), globose (Ampullaria, Natica, Fig. 150 B), with almost all conceivable gradations between these types. The number of whorls is best counted by placing the shell mouth downwards, and reckoning one for every suture that occurs between the extreme anterior point of the shell and the apex. The mouth or aperture may be (a) entire, as in feliz, Natica, Ampullaria, when its peristome or margin is not interrupted by any notch or canal, or (6) prolonged at its anterior and sometimes also at its posterior end into a canal. The anterior canal serves as a protection to the siphon,! the posterior canal is mainly anal in function, and corresponds, in part, to the hole of Mssurella, the slit in Plewrotoma and Emarginula, and the py... i275 — Anal row of holes in Haliotis. The mouth presents _ slitin Pleuro- every variety of shape, from the perfect circle in Cyclostoma and Trochus, to the narrow and prolonged slit in Conus and Oliva. The right margin of the mouth (the left, in sinistral shells) 1 Strombus and Pteroceras (see Fig. 99, p. 200) exceptionally develop a siphonal notch which is distinct from the anterior canal. 264. PARTS OF THE UNIVALVE SHELL CHAP. is termed the outer lip or labrum, the left margin the inner lip, labium, or columella lip... In young shells the outer lip is usually thin and unfinished, while in the adult it is generally thickened into a rib, or furnished with more or less prominent teeth, or given an inward or outward curve. In some genera, especially the Strombidae, the outer lip of the adult develops long finger-like processes, which sometimes attain an extraor- dinary size (chap. xiv.). As growth proceeds, these marginal teeth and ribs are either dissolved and disappear, or are perma- nently incorporated, in the shape of varices, with the framework of the shell. Some shells, e.g. Watica, Turritella, Actaeon, have Fic. 176. — Solarium perspectivum Fic. 177. —Section of Turbinella Lam., from the under side. pyrum L., showing the plicae on the columella and the growth of successive whorls. a permanently unfinished outer lip, even in the adult stage. The columella lip varies in shape with the mouth as a whole ; thus it may be straight, as in Conus, or excavated, as in Sigaretus, Struthiolaria, and Bulla. Frequently it is continued by part of the body whorl, as in Ficula, Doliwm, and Fasciolaria. The folds or plaits on the columella, which are often charac- teristic of the genus or even family (e.g. Fasciolariidae, Mitridae, Turbinellidae) are not merely external, but continue down the 1 The columella, as distinct from the columella lip, is the solid pillar of shell round which the whorls are coiled (Fig. 177), the lower, or anterior portion of which alone is usually visible. Ix THE SLIT 265 whole spire (see Fig. 177, which also shows how successive fresh growths have thickened the columella). The whorls may be wound in a spiral, which is either hollow, as in Solarium, or quite compact, as in Oliva, Terebra, Cypraea, with every possible intermediate grade. This concavity, which varies in depth and width, is known as the wmbzlicus, and shells are accordingly spoken of as deeply (e.g. most Trochidae and Naticidae), narrowly (e.g. Lacuna, LInttorina), or widely (e.g. Solarium) umbilicated. When the spiral is quite flat, as in Planorbis and some Helix, the umbilicus vanishes entirely. Shells in which the whorls are so compactly coiled on an ascending spiral that there is no umbilicus, are termed ¢mper- Fforate. The Slit. — Many shells are furnished with a slit in the last whorl, which opens, in most cases, on the outer lip, and is some- Fic. 178. — The slit in A, Hemitoma, B, Emarginula, C, Macroschisma, D, Craniopsis, E, Puncturella, F, Fissurella. times of considerable depth, at others a mere notch. In the patelliform shells it is always in front of the apex. The function of the slit appears to be mainly anal, the excretory products being thus allowed to escape by a passage of their own, without soiling the clean water taken in by the branchiae. The posterior canal of some Gasteropoda probably performs a similar function. In the adult Fissurella the slit becomes an apical hole (see Fig. 178 F), in the allied genera it is either immediately in front of the spire (Puncturella), or half-way between the spire and the anterior margin (#zmula), or on the margin and well marked (ELmarginula), or a mere indentation of the margin (Hemitoma). In Pleurotomaria it is exceptionally long, and is well marked in Bellerophon, Schismope, Scissurella, Murchisonia, and Pleurotoma (where itis sutural). In Haliotis and Polytremaria it is replaced by a series of holes, which are closed up as the animal grows past them. Some of these holes (at least in Haliotis) certainly 266 THE SLIT —THE TUBED OPERCULATES CHAP. serve the purpose of admitting water to the branchiae, while others are anal. In Trochotoma there are only two holes, united by a narrow fissure. The Tubed Land Operculates. — A group of the Cyclophoridae, which is restricted to Further India and the great Malay Islands, has devel- oped a remarkable sutural tube on the exterior of the last whorl, near the aperture, A similar tube, but more obscure, exists in Alycaeus. == Several stages in the development Fie. bln slit in ise of this tube may be noticed, begin- B, Pleurotomaria, C, Schismope, Ning with the elevation of part of az Polytremaria, B, Haliotis (not the peristome into a simple irregu- awn to scale). ‘ 5 é lar shelly plate, which is continued, first into a short, and then into a long tube, which becomes soldered to the shell; finally, the tube becomes free, and the anterior part of the last whorl is disconnected from the spire (Fig. 180 A-D). It is singular that the tube does not appear to be of any use to the animal, since its internal extremity, in the complete form, Fic. 180. — Development of the tube in the tube operculates: A, Pterocycus rupestris Bens.; B, Opisthoporus birostris Pfr.; C, Spiraculum travancoricum Bedd.; D, Rhiostoma Housei Pfr. is closed, and does not communicate with the interior of the whorl. It may be presumed, however, that in origin the tube served as a means of conveying air to the animal when the operculum was closed. The holes in the peristome of Pupina, Cataulus, and Anostoma (Fig. 154) may be compared. 1X THE OPERCULUM 267 The Operculum. — The operculum is a cuticular development of a group of cells situated on the dorsal side of the foot, exactly over the terminal point of the fibres of the columellar muscle. It is so situated that in crawling it is generally carried free of the shell, some- times at the extreme upper end of the foot, more usually somewhat nearer to the shell (Fig. 181). In Pterocyclus itis pushed back into the umbilicus when the animal is in motion. F/= Ky The operculum is present in nearly all 2 S) Ee, : COM th gh land, fresh-water, and marine Prosobran- 5 pa San ; : ; ; : "OR: chiata, absent in all Opisthobranchiata in yg. 181 zournaspirata the adult state, except Actaeon, and in all Lam., E. Indies. F, Pulmonata, except Amphibola. It has been oe ee lost in the following marine Prosobran- __ T, tentacles, with eyes é a . at their base. (After chiata: many Cancellariidae and Conidae, Souleyet.) Oliva (though present in Olivella and Ancilla), Harpidae, Marginellidae, Voluta proper (though pres- ent in V. musica), nearly all Mitridae, Cypraeidae, Doliidae, Ianthinidae; and, of land genera, in Proserpinidae. It is evi- dent, therefore, that its presence or absence is of limited value in classification. In some species of Ampullaria and Natica it is horny, in others shelly. Dall found that in a number of specimens of Volutharpa ampullacea, 15 p.c. had opercula, 10 p.c. traces of the operculigenous area, but no operculum, the rest no trace of either. Monstrosities of Buccinum undatum some- times occur, which have two, or in rare case three opercula. As a rule, the operculum exactly fits the mouth of the shell. But in cases where the mouth is very large (e.g. Conus, Strombus, Concholepas, some Bullia), it only covers a very small portion and is quite inadequate as a protection (Fig. 62, p. 155). Again, when the shell has assumed a more or less limpet-shaped form, and habitually adheres to flat surfaces without much occasion for locomotion, the operculum becomes degraded and is probably on the way to being lost altogether. This is the case with MVavw- cella (a modified Nerita, see Fig. 18, p. 17), Concholepas (a modi- fied Purpura), Sigaretus (a modified Natica). Probably the more completely patelliform shells of Crepidula, Haliotis, Fissurella, ’ 268 THE OPERCULUM CHAP. and Patella have reached the stage at which the operculum has been lost entirely. In Navicella, besides becoming degraded, the operculum has actually become partly internal, and apparently serves the purpose of separating the viscera from the upper part of the foot, something like the shelly plate in Crepidula. This explains why the operculum in this genus is polished on both sides. Some authors have imagined that the operculum is homo- logous (a) to the second valve in Pelecypoda, (6) to the byssus. It differs, however, morphologically from the former in the essential point of not being produced by the mantle, and from the latter in not being produced by a special gland. As regards shape and formation, the operculum has usually a more or less well-marked nucleus which may be central (e.g. Invona), subcentral (Ampullaria), lateral (Purpura), or terminal Turbo Turbo Livona Ampullaria Natica (Sarmaticus) (Callopoma) ; Fig. 182. Various forms of opercula. (Pyrula). Asa rule,-both the inner and outer surfaces are fairly flat, but in Torinia, Cyathopoma, and Pterocyclus the outer sur- face is elevated and conically spiral, in some Turbo (e.g. Sarmati- cus) it is covered with raised tubercles resembling coral, while in others (e.g. Callopoma) it is scored with a deep trench. Avlo- poma, a land genus peculiar to Ceylon, has a paucispiral oper- culum with hollow whorls, deceptively like a Planorbis ; it fits over the aperture instead of into it. In JZivona and most Trochidae the operculum is cartilaginous and multispiral. In Strombus it is narrow, curved, and often serrated like a leaf on one of the edges; in Conus it is narrowly oblong and rather featureless ; in Littorina, paucispiral and always cartilaginous. 1J. E. Gray, Phil. Trans. 1888, p. 812. IX PARTS OF THE SHELL IN BIVALVES 269 In many cases (e.g. Paludina) there is no true spiral form, but the striae are concentric to a nearly central nucleus, and thus give the appearance of a spiral. The evolution of the oper- culum in Navicella from Nerita has already been illustrated (p. 49). Neritopsis has a very remarkable operculum, the striated Purpura Littorina Aulopoma Torinia Neritopsis Conus ee x3 Strombus x 2 Fic. 183. — Various forms of opercula. appendage of which locks behind the columella of the shell, like the tooth in the opercula of the Neritidae. Terms employed to denote various parts of the Bivalve Shell. — The wmbo, or beak, is the apex of the hollow cone, of which each valve may be regarded as consisting. This apex is usually more or less twisted: it is markedly spiral in Lsocardia, Diceras, some Chama, and especially Requienia, while in Pecten, Lepton, and others the spiral is altogether absent. As a rule the umbones point forward, t.e. towards the anterior end of the Shell. In Donax, Nucula, and Trigona, however, they point backward. The umbones are generally more or less approxi- mated, but in Arca they are widely separated. An equilateral shell is one in which the umbones are more or less central with regard to its anterior.and posterior portion, while in an ineguilateral shell the umbones are much nearer one end than the other. On the other hand, eqguivalve and inequi- valve are terms used to express the relation of the two valves to one another as a whole. Thus nearly all bivalve shells are more or less inequilateral, but a comparatively small proportion are inequivalve. The dorsal margin is adjacent to, the ventral margin opposite to, the umbones. The anterior and posterior margins are respec- tively the front and hinder edges of the shell. The muscles which serve to close the valves leave impressions on the inner surface of each valve. These, when both muscles are present, are known as the anterior and posterior adductor 270. PARTS OF THE SHELL IN BIVALVES CHAP. impressions. The impression produced by the muscular edge of the mantle, which curves downwards and backwards from the anterior adductor impression, is known as the pallial line. In shells with only one muscle it is represented by an irregular row of small marks, or disappears altogether (Ostrea). ‘The pallial sinus is produced by the muscles which retract the siphons, and is most marked in those genera in which the muscles are powerful and the siphons large (e.g. Tellina, Mya). It is entirely absent in genera possessing no retractile siphons. Fic. 184. — Left valve of Venus gnidiaL.: Fia.185.— Right valve of Lucina tigerina A, anterior, B, posterior, C, dorsal, L.: A, anterior, B, posterior, C, dorsal, D, ventral margin, AB, length, CD, D, ventral margin; AB, length, CD, breadth of shell. breadth of shell. a.m, anterior; p.m, posterior adduc- a.m, anterior; p.m, posterior ad- tor muscle; p, pallial line; p.s, pallial ductor muscles; p, pallial line; /, liga- sinus; /, ligament; /u, lunule; w, umbo; ment; u, umbo; c¢, cardinal teeth; a.l, c, cardinal teeth; a./, anterior lateral p.l, anterior and posterior lateral tooth; p.l, posterior lateral tooth. tooth. Right and Left Valve. — The simplest way of distinguishing the valves as right and left is to hold the shell in such a way that the siphons point towards the observer, and the mouth away from him; in this position the valve to the right is called the right valve, and the valve to the left the left valve. If, however, the animal is not present, it may be remembered that the liga- ment is nearly always behind the beaks, and that the beaks, as a rule, point forward, thus the right and left valves can generally be named by observation of the beaks and ligament. When the ligament is median to the valves (e.g. Ostrea, Pecten), and the beaks are not curved, the valves may be recognised by noting the fact that the impression of the adductor muscle (in these be : THE LIGAMENT AND HINGE 271 cases always single) is nearer to the posterior than to the anterior side. In a similar way the pallial impression, which only forms a sinus on the posterior side, furnishes a guide to the valves of Donazx, in which the beaks point backward, and of Tellina, in which the beaks are frequently central. In the fixed inequivalves (e.g. Chama) it is sometimes the right, sometimes the left valve which is undermost, but the fixed valve, whether right or left, is always deep, and the free valve flat. Ostrea and Anomia are always fixed by the left valve. The dunule is a well-marked area in front of and close to the umbones, usually more or less heart-shaped, and limited by a ridge. Generally it is shallow, but sometimes, as in Dosinia, Opis, and some Car- dium, deeply impressed. A corresponding area behind the umbones, enclosing the ligament, is called the escutcheon (Fig. 186), but it seldom occurs. The ligament is a more or less elastic band, which unites the two valves along a line adjacent to the umbones. As a rule, the greater part of Fic. 186.— Venus the ligament is external to the shell, but it may ie a en : be entirely internal. It is placed, normally, oe i behind the umbones, but in a few cases, when ympbones. _ the hinge line is very long (Area, Pectunculus), it extends in front of them as well. The edges of the valves, when the ligament is mainly external, are more or less excavated for its reception. When internal it is generally contained in a groove or spoon-shaped pit, known as the fossette (compare Fig. 187). The ligament consists of two distinct parts, which may occur together or separately, the external, or ligament proper, and the internal, or cartilage. Only the external portion can be seen when the valves are closed. As a rule, the two portions are intimately connected with one another, the ligament folding over the cartilage, but in some cases, e.g. Mya, Mactra, where the cartilage is lodged within the hinge, they are completely disconnected (Fig. 187). In Pecten the external ligament is very thin, and runs along the dorsal margin, while the internal ligament is large, solid, and situated in a shallow pit. In Perna, where the hinge is 272 . THE LIGAMENT AND HINGE : CHAP. toothless, the ligament is folded into a number of transverse ridges, which fit into corresponding grooves in the shell. The ligament proper is zmelastic and insoluble in caustic potash. The cartilage is very elastic, composed of parallel fibres, slightly iridescent, and soluble in caustic potash. The operation of the ligament —using the word as including the whole ligamental process —is in opposition to that of the adductor muscles. When the latter close the valves, they compress the hgament, an action which its elas- ticity resists: thus its operation tends in part towards keeping the valves open. But when ligament and cartilage are both fully de- veloped, they work in opposition to one another, the ligament, by its resistance to compression, prevent- ing any straining of the adductor bie muscles when the valves are open, ee Hinge oF iene ve; and the cartilage, for the same edulis King; ca, cardinals; l.a, reason, preventing the ventral mar- anterior laterals; /.p, posterior _- f . laterals; f, fossette; c, cartilage; S108 of the shell from closing too 1, ligament. rapidly upon one another when the valves are being shut. The Hinge. — The valves of Pelecypoda are generally articu- lated, below the umbones, by a Ainge which is furnished, in the majority of cases, with interlocking teeth, small pits or depres- sions in each valve corresponding to the teeth in the other. The teeth are distinguished as cardinal, or those immediately below the umbo, and lateral, or those to either side of the car- dinals, the latter being also distinguished as anterior and pos- terior laterals, according as they are before or behind the umbo (Fig. 184). In shells which are tolerably equilateral there is no difficulty in distinguishing between cardinal and lateral teeth. But when they are very inequilateral, the whole hinge may share in the inequality of growth, and an anterior lateral may be thrown backward and simulate a cardinal, or a cardinal may be thrown backward and simulate a posterior lateral (e.g. Cardita, Unio, Fig. 188). In many Chama the cardinals are pushed up into the umbo and become a mere ridge, while the IX THE LIGAMENT AND HINGE 2732 strong anterior lateral becomes nearly central and simulates a cardinal. Some bivalves, e.g. Anodonta, Ostrea, Pedum, many Mytilus, have no hinge teeth at all, in others the laterals are wanting Fic. 188. — Hinges of A, Cardita semiorbiculata Brug., and B, Unio rectus Lam., showing how, in inequilateral shells, the lateral teeth tend to shift their position. a.m, anterior adductor, p.m, posterior adductor muscle; c, c, cardinal teeth; p.l, posterior lateral teeth; 7, ligament. (Psammobia, Diplodonta). In the Arcadae the hinge consists of a number of very similar denticles, which are often serrated like the teeth of a comb (Fig. 189). Hinge-teeth are probably, in origin, derived from the crenula- Fic. 189. — The hinge in Arcadae: Fig. 190.— A, Tridacna scapha Lam.; B, A, Nucula Loringi Ang. x 4; Cardium enode Sowb., showing the inter- B, Arca granosa L.; u.a, um- locking of the ventral margins. bonal area. tions or ribbings of the surface of the shell, the upper ends of which impinge upon the dorsal margin and mark it in a way which is quite recognisable when the shell is thin. Similar erenulations, resulting in interlocking of the valves, are not VOL. II T 274 HINGE-TEETH AND OTHER PROCESSES CHAP. uncommon upon the ventral margin in certain genera (Fig. 190). The mechanical effect of these continued riblets, when fitted together on the opposing valves, would be to prevent the valves sliding upon one another while closing, or after being closed. Thus there would be a probability of their surviving, even after the ribbing had disappeared from the surface of the shell, the increased strength given by the hinge compensating for, and making it possible to do without, the extra strength supplied by the ribs. It is therefore possible that the teeth of the Nuculidae and Arcadae, which have no distinction between cardinals and laterals, represent a very ancient type, from which have been evolved the various forms of hinge in which cardinals and laterals are distinguished. Even in some forms of Arcadae (comp. Pec- tunculus) we get a hint how the transverse teeth of the typical Arca may have become transformed into the longitudinal tooth of the normal lateral.} The developed hinge-teeth, then, ensure the opening of the valves in one direction; they also secure their accurate closure upon one another in exactly the same plane. Exposed shells and gaping siphons matter little to animals which are protected by their burrowing propensities, but to those which live in material which can be easily penetrated by their foes, it must be of advantage to be able to buckle their armour absolutely tight. The edentulous hinge of Anodonta is a degeneration from a dentate type, which retains its teeth (in Unio, etc.) when subject to the jar of rapid streams, but tends to lose them in the stiller waters of canals, lakes, and ponds. Other processes in the bivalve shell. —In Anatina each umbo is fissured and strengthened on the inside by a kind of umbonal plate which carries the ligament. Some forms of Liligna de- velop a strong internal umbonal rib, which serves as a buttress to strengthen the shell. In Pholas, the so-called falciform pro- cess serves as a point of attachment for the muscles of the foot and viscera. There is no ligament or hinge-teeth, the place of the latter being taken by the anterior adductor muscle, which is attached to the hinge-plate, the latter being reflected back into the shell. In Septifer the anterior adductor muscle is carried on a sort of shelf or myophore, and in Cucullaea the posterior 1W. H. Dall, Amer. Journ. Sc. xxxviii. p. 445 f. IX MEASUREMENT—THE PERIOSTRACUM 275 adductor is partly raised on a similar and very prominent formation. Length and breadth of bivalve shells is variously measured. Most authorities measure length, or ‘ antero-posterior diameter,’ by a straight line drawn from the extreme anterior to the extreme posterior margin, and breadth by a similar line, drawn from the umbones to a point, not very clearly marked, on the opposite ventral margin (see Figs. 184 and 185). Others, less correctly, reverse these terms. Thickness is measured by the extreme distance of the opposite faces of the closed valves. As a rule, the length exceeds, and often greatly exceeds, the thickness, but in a few cases—e.g. the Cardissa section of Cardium — this is reversed. The periostracum. — Nearly all shells are covered, at some period of their growth, by a pertostracum,! or surface skin, which serves the purpose of protecting the shell against the destructive effects of the chemical action set up by water or air. It also, in some cases (see p. 258), acts as a kind of base upon which the shell is de- posited. In old shells it is commonly worn away, especially at those parts which are likely to become abraded. The form and composition of the periostracum varies greatly. Some- times (e.g. Oliva) it is a mere trans- parent film, at others (Zonztes) it is transparent, but stout and solid. It is corneous in WNSolenomya, covered with fine hairs in many Helicidae, in Conus, Velutina, and Cantharus it is thick, fibrous, and persistent ; in Tri- Fig. 191. — Triton olearium L.., chotropis and some Triton it is fur- Mediterranean, an example of nished with long bristles on a thick nea poet Peet ground (Fig. 191). In fresh-water shells it is usually rather thick, in order to protect the shell from the erosive powers of certain kinds of water. In some cases (Mya, Anatina) the periostracum is continued over the siphons, so as to form a protection throughout their whole length. 1 The term epidermis, as distinct from periostracum, is properly restricted to the outer layer of the skin of the mantle and body generally. 276 EROSION OF THE SHELL CHAP. IX Erosion. — The fresh-water Mollusca generally, and marine mollusca in a few rare cases (Purpura, Littorina) are subject to erosion, or decay in the shell substance. In univalves erosion usually sets in near the apex (Fig. 192), where the life of the shell may be regarded as weakest, and in bivalves near the umbones. It is commonest in old shells, and rarely occurs in the very young. So long as the periostracum is present to protect the shell, erosion cannot set in, but when once it has been removed the shell is liable to the chemical changes set up in its substance by water. ‘There is abun- dant evidence to show that erosion is caused by pollution of water. Out of many instances one must suffice. Ina certain stream near Boston, U.S., numbers of Mollusca-occurred, the shells of which Fie. 192. — Ex- ample of an Were very perfect and free from disease. Some ee pct little way down stream an alkaline manufactory (Melaniacon- Grained its refuse into the water. At and below fusa Dobrn, this point for some distance every shell was more Ceylon). 3 or less eroded, most of them seriously. Farther down, when the alkali refuse became diluted away, the shells retained their normal condition. A small percentage of lime in the water appears to produce erosion. The result of some experiments by G. W. Shrubsole, in the investigation of this point, may be tabulated as follows :?— : Water from ete Result River Dee, near Chester . 98°00 grs. acted strongly on shells Wrexham 200 % ; . 4-00 grs. a es fr River Dee, near Llanderyel . 0°53 grs. _ of PH Trent Canal . : : . 833 ers. no action 5 “Cp Lewis, Proc. Bost. Soc. vi. p. 149. 2 Journ. of Conch. v. p. 66. CHAPTER X GEOGRAPHICAL DISTRIBUTION OF LAND AND FRESH-WATER MOLLUSCA — THE PALAEARCTIC, ORIENTAL, AND AUSTRAL- ASIAN REGIONS Tae Mollusca afford specially valuable evidence on prob- lems of geographical distribution. This fact is largely due to their extreme susceptibility to any change in the conditions of life. Genera which are accustomed to live in a certain temper- ature and on certain food, cannot sustain life if the temperature falls or rises beyond certain limits, or if the required food be not forthcoming. There is therefore a marked contrast between the Mollusca of the tropics and of the temperate zones, while different regions in the same latitude, whether within or with- out the tropics, often show great diversity in their fauna. Every region is thus characterised by its Mollusca. The Mol- lusea, for instance, of Australia or of South Africa characterise those countries quite as much as do the kangaroo and the emu, the hartebeest and the ostrich; there is nothing lke them any- where else in the world. In the Greater Antilles the Mollusca stand out beyond all other forms of life as characteristic of the islands as a whole, and of each separate island in particular. The geographical distribution of the land and fresh-water Mollusca must be considered quite apart from that of the marine Mollusca. The sea offers no such serious barriers to the spread of the latter as the land does to the spread of the former. If we were to journey to the Azores, and turn our attention to the land-snails, we should find them almost wholly peculiar, while amongst the sea-shells we should recognise many as occurring also on our southern coasts, and few that were different from those of the Mediterranean. The marine Mollusca of the Sand- 277 278 LOCALISATION OF GENERA AND SPECIES CHAP. wich Islands, in spite of the enormous intervening distance, are not very different from those of Natal, but the land Mollusea of the two countries are as widely different as is possible to imagine. Land Mollusca are, as has been remarked, fettered to the soil. Quadrupeds, birds, fishes, and reptiles are provided with organs of motion which enable them to overpass barriers of various kinds. Even plants, although themselves incapable of motion, may be conveyed in every direction by means of seeds, which are either wafted by the wind or adhere to the skin of animals. But the Mollusca have no such regular means of transport, and are, in a large number of instances, limited to districts of a certain char- acter of soil, or producing certain kinds of vegetation. The localisation, both of genera and species, occurs all over the world. The genus Achatinella, which is peculiar to the Sandwich Islands, is found there in a profusion of species. It lives in the mountain valleys which radiate from the central ridge of each island, and each valley is characterised by its own peculiar set of species. The great carnivorous Glandina is restricted to Central America and the adjacent parts of the two continents, with one or two species in Southern Europe. Bulimus proper is restricted to South America; Achatina to Africa south of the Sahara; Yornatellina to the Pacific Islands; Cochlostyla to the Philippines; Cylindrella and Bulimulus are peculiar to the New World; Buliminus, Nanina, Scarabus, and Cassidula to the Old. Extreme cases of this restriction of habitat sometimes occur. Thus Limnaea involuta is found only in a single small mountain tarn in Ireland; Clausilia scalaris along a narrow strip of lime- stone in Malta; Strophia nana is confined to a few square rods on an island that is itself a mere dot in the Caribbean Sea; the genus Camptonyx occurs only in the neighbourhood of Mt. Girnar, in Gujerat; and Lantzia in moss on the top of a mountain in Bourbon. Attempts to colonise snails in strange localities have usually resulted in failure, especially when the attempt has involved serious changes of environment. The common Cochlicella acuta of our coasts resists all endeavours to establish it beyond a cer- tain distance from the sea. Snails brought from the Riviera and placed under almost similar conditions of climate on our own southern coasts have lived for a while, but have very rarely taken x ARTIFICIAL TRANSPORT OF SPECIES 279 permanent root. Mr. H. W. Kew! has collected a good many of these attempts to acclimatise species, the general success of which seems to depend almost entirely on a restoration of the old conditions of life. At the same time there are certain species which exhibit a curiously opposite tendency, and which seem capable of flour- ishing in almost any part of the world, and under the most varied surroundings. Our own common garden snail (Helix aspersa) is a striking instance of this adaptability to new condi- tions. It has been established, by art or by accident, in Nova Scotia, Maine, South Carolina, New Orleans, California, Mexico city, Cuba, Hayti, Cayenne, Brazil, Valparaiso, Cape Town, the Azores, St. Helena, Mauritius, Loyalty Islands, and Australia. - The great Achatina fulica of East Africa has been established first in Mauritius, and from thence has been carried to the Seychelles and Calcutta. Helix lactea,a common Mediterranean species, has been carried to Teneriffe and Montevideo; Helix similaris, whose fatherland is Eastern Asia, has been transported to Mauritius, Bourbon, West Africa, West Indies, Brazil, and Australia; Hnnea bicolor (Kastern Asia) to India, Bourbon, Mauritius, West Indies; Stenogyra decollata (Mediterranean basin) to South Carolina; S. Goodall (West Indies) to British pineries ; Helix Hortensis to New Jersey. Seven common Eng- lish species (Limazx gagates, Hyalinia cellaria, H. alliaria, Helix aspersa, H. pulchella, Pupa umbilicata) have become naturalised in St. Helena,? and as many as nineteen in Australia.? Cases of artificial transport of this kind are readily detected ; they follow the lines of trade. The snails themselves or their ova have been accidentally enclosed with plants or mould, or have adhered to packing-cases, or to hay and grass used in pack- ing. Thus they constitute no disturbance to the general rule of the persistent localisation of species and genera, and there is little fear that the evidence which the geographical distribution of the Mollusca brings to bear upon the general problems of distribution will be confused by any intermixture of fauna naturally distinct. Land Mollusca: Barriers to Dispersal.— The chief natural barriers to dispersal are extremes of temperature, the sea, mountain ranges, and deserts. Rivers, however large, seem of _1The Dispersal of Shells, pp. 182-195. 2H. A. Smith, P.Z. 8. 1892, p. 259. 3C. T. Musson, Proc. Linn. Soc. N. S. Wales (2), v. p. 883. 280 BARRIERS TO DISPERSAL CHAP. little effect in checking dispersal. There is no appreciable difference between the land Mollusca north and south of the Ganges, or north and south of the Amazon. Living snails, or their ova, are no doubt transported from one bank to another on floating débris of various kinds. The barrier offered by the sea is obvious, and at first sight appears insurmountable; but the facts with regard to oceanic groups of islands like the Azores and Canaries (see p. 297) show that even a stretch of salt water many hundred miles in breadth may be ineffectual in preventing the dispersal of Mollusca. Mountain ranges, provided they are too high to be scaled, and too long to be turned in flank, offer a far more effective barrier than the sea. Every thousand feet upward means a fall of so many degrees in the mean temperature, and a change, more or less marked, in the character of the vegetation. ‘There is generally, too, a considerable difference in the nature of the climate on the two sides of a great mountain range, one side being often arid and cold, the other rainy and warm. The combined effect of these influences is, as a rule, decisive against the dispersal of Mollusca. Thus the Helices of Cali- fornia are almost entirely peculiar; one or two intruders from states farther east have succeeded in threading their way through the deep valleys into the Pacific provinces, but not a single genuine Californian species has been able to scale the heights of the Cascade Mountains. The land Mollusca of India are numbered by hundreds; not one penetrates north of the Himalayas. According to, Mr. Nevill! the change from the Indo-Malayan to the so-called European molluscan fauna at the northern watershed of the Kashmir valley is most abrupt and distinct; in two days’ march northward, every species is different. Ranges of inferior altitude, such as the Pyrenees, the Carpathians, or the Alleghanies, may be turned in flank as well as scaled, and we find no such marked contrast between the Mollusca on their opposite sides. The most effective barrier of all, however, is a desert. Its scorching heat, combined with the absence of water and of vegetable life, check dispersal as nothing else can. The distri- bution of the Mollusca of the Palaearctic Region is an excellent instance of this. Their southern limit is the great desert which 1 Scient. Results Sec. Yarkand Exped. “ Mollusca,’’ pp. 1-16. x BARRIERS TO DISPERSAL 281 stretches, with scarcely a break, from the west coast of Africa to the extreme east coast of Asia. The Mediterranean offers no effectual barrier; shells of southern Europe are found in pro- fusion in Morocco, Tunis, and Egypt, while all through Siberia to the extreme of Kamschatka the same types, and even the same species, of Mollusca occur. A detailed examination of the means, other than voluntary, by which Mollusca are transported from one place to another hardly comes within the scope of this work. Ocean currents, rivers, floods, cyclonic storms of wind, birds, and even beetles and frogs, play a part, more or less considerable, in carrying living Mollusca or their ova, either separately or in connexion with floating débris of every kind, to a distance from their native home. Accidental locomotion, of one or other of these kinds, combined with the well-known tenacity of life in many species (p. 387), may have contributed to enlarge the area of dis- tribution in many cases, especially in the tropics, where the forces of nature are more vigorous than in our latitudes. The ease with which species are accidentally spread by man increases the probability of such cases occurring without the intervention of human agency, and numbers of instances may be collected of their actual occurrence.? A point, however, which more concerns us here is to remark on the exceedingly wide distribution of the prevailing forms of fresh-water Mollusca. It might have been expected that the area of distribution in the fresh-water forms would be greatly restricted, since they cannot migrate across the land from one piece of water to another, and since the barriers between pond and pond, lake and lake, and one river system and another are, as far as they are concerned, all but insuperable. We might have expected, therefore, as Darwin and Wallace have remarked, to find a great multiplicity of species confined to very restricted areas, since the possibility of communication with the parent stock appears, in any given case, to be so exceedingly remote. As is well known, the exact reverse occurs. The range, not merely of genera, but even of individual species, is astonishingly wide. ‘This is especially the case with regard to the Pulmonata and Pelecypoda. The genera Limnaea, Planorbis, Physa, An- eylus, Unio, and Cyclas are world-wide. Out of about ten genera 1 Mr. H. W. Kew, The Dispersal of Shells, has brought together a very large series. 282 WIDE DISTRIBUTION OF FRESH-WATER MOLLUSCA cHap. of fresh-water Mollusca in New Zealand, one of the most isolated districts known, only one is peculiar. In South Africa and the Antilles no genus is peculiar. In the latter case, this fact is remarkable, when we consider that the same sub-region has at least ten peculiar genera of operculate land Mollusca alone. To give a few instances of the distribution of particular species : — LTimnaea stagnalis L. occurs in the whole of Europe, and northern Asia to Amoorland, Turkestan, Afghanistan, North Persia, and Kashmir; Greenland, North America from the Atlantic to the Pacific, and from North Canada and British © Columbia as far south as Texas. The distribution of LZ. peregra Mull., ZL. truncatula Mull, and L. palustris Mull. is almost equally wide. Planorbis albus occurs in the whole of Europe, and northern Asia to Amoorland, Kamschatka, and Japan; Turkestan, the Altai-Baikal district, Alaska and Greenland, North Canada, and the whole of eastern North America. The distribution of Anodonta anatina L., Cyclas cornea L., and Pisidiwm pusillum Gmel. is almost equally wide. It is evident that the accidental means of transport mentioned above are insufficient to account for the facts as we find them ; we are therefore compelled to seek for further explanation. Anything in the nature of a current furnishes a ready means of transport for Mollusca which have obtained a footing in the upper waters of a river, and there is no difficulty in imagining the gradual spread of species, through the agency of floods or otherwise, over a whole river system, when once established at any point upon it. The feeble clinging power of newly-hatched Limnaea has often been noticed as contributing to the chances of their range of distribution becoming extended. Fresh-water Mollusca, too, or their ova, are exceedingly likely, from their extreme abundance, to be transported by water-birds, which fly without alighting from one piece of water to another. Again, the isolation of one river system from another is, in many instances, by no means well marked or permanent, and a very slight alteration of level will frequently have the effect of diverting the supplies of one watershed into another. When we know what enormous oscillations in level have taken place over practically the whole surface of the globe, we can recognise the x ATTEMPTS AT EXPLANATION 283 probability that the whole river system of the earth has been mixed up and reconstructed again and again, with a very thorough blending of adjacent fauna. ; It is possible that the very uniform conditions under which fresh-water Mollusca live may have something to do with the uniformity of their distribution and the comparative sameness in their development. ‘There can scarcely be any question that the environments of fresh-water species are in themselves less varied and less lable to fluctuation than those of species whose home is the land. Water is very like water, all the world over; it may be running or motionless, warm or cold, clear or muddy, but the general tendency is for it to be free from extremes of any kind. Even if the surface water of a lake or river freezes, or becomes unusually hot, there is generally plenty of water ata lower stratum which maintains a less extreme temperature, and to which creatures can retire on the first symptoms of a change. From this two results will follow. Not only will the inhabitants of a piece of water not be inclined to vary much from the type, since their whole surroundings, food, etc., continue very much the same, but, if transported by any accident or cataclysm else- where, they will be exceedingly likely to arrive at a place which closely resembles their former home in all essentials. Thus the tendency for new types to be formed would be constantly checked, or rather would very seldom arise. Mr. Belt, while recognising the importance of changes of level as affecting the distribution of fresh-water species, appears to regard the operations of such changes from a rather different point of view to that described above. “I think it probable,” he writes,! “that the variation of fresh-water species of animals and plants has been constantly checked by the want of continuity of lakes and rivers in time and space. In the great oscillation of the surface of the earth, of which geologists find so many proofs, every fresh-water area has again and again been de- stroyed. .. . Thus species of restricted range were always exposed to destruction, because their habitat was temporary and their retreat impossible, and only families of wide distribution could be preserved.” The terrestrial surface of the globe has been divided, as indi- cating the facts of geographical distribution, into six regions — 1 The Naturalist in Nicaragua, p. 334 f. ) 284 REGIONS OF DISTRIBUTION CHAP. the Palaearctic, Oriental, Australasian, Ethiopian, Nearctic, and. Neotropical. To these is sometimes added a seventh, the Neant- arctic, consisting of Chili and Patagonia (and certain islands of the south Atlantic); but since the Mollusca of Chili unmis- takably form a part of the Neotropical fauna, it seems hardly worth while to recognise a separate region for those of the extreme south of South America, which have no peculiar char- acteristics. In certain points the exact limits of these regions, as indi- cated by the Mollusca, will probably not correspond to those which are marked out by other zoological classes. Wallace’s line, for instance, does not exist, as far as the Mollusca are concerned. These regions may be further subdivided into sub-regions, thus : — Regions Sub-regions Regions Sub-regions ( Septentrional ( Central African Palaearctic { Mediterranean Ethiopian 4 South African | Central Asiatic | Malagasy : Indo-Mala : American ee cay { Chinese : eee { Californian f Antillean ( Papuan | Central American Australasian { Australian Neotropical { Colombian | Polynesian Brazilian | Chilian A. The Palaearctic Region The southern boundary of this region is the northern limit of the African Sahara, the Mediterranean forming no break what- ever in its continuity. In Asia this boundary is less well marked, but roughly corresponds to the southernmost of the vast ranges of mountains which border the great tablelands of central Asia. Across Africa the line of desert is well defined; but in the north-east, as the desert approaches more nearly to the sea, the African extent of the region is correspondingly narrowed until it becomes little more than a strip of coast land, scarcely widening even in Lower Egypt. On the Morocco coast, Palae- arctic land forms penetrate as far south as Cape Nun. At its eastern extremity the line becomes less well defined, but 1 Morelet, Journal de Conch. 1875, p. 194. x THE PALAEARCTIC REGION 285 probably proceeds along the snowy mountains west of Setchouan, the Pe-ling and Tan-sia-shan ranges, so as to include all the high ground of Thibet and of the upper waters of the Hoang-ho, and ultimately reaches its eastern limit at some point on the shores of the Sea of Japan. The region thus includes all Europe, Africa north of the Sahara, with the Atlantic islands (the Azores, Canaries, etc.), North Arabia, Asiatic Turkey, the greater part of Persia, Afghanistan, Thibet, all Asiatic Russia, and a very large portion of the Chinese empire. _ The principal characteristics of the region as a whole are: — (1) The rich development of Helix, Arion, Limax, Buliminus, and Clausilia. (2) The comparative absence of land operculates (see map, Frontispiece). | (3) The uniform character of the fresh-water fauna. It is in the southern portion of the region that Helix Gn the sub-genera Macularia, Iberus, Pomatia, and Xerophila) and Buliminus (Zebrina, Chondrula, Ena) attain their maximum. In the north, Fruticicola is the characteristic group; in the mountainous districts of the south-east, Campylaea, with Clausilia. The Arionidae have their head-quarters in the damp and warm regions of western Europe, but are rare in the south. They only approach the Mediterranean coast in Algeria, near Gibraltar, and in the region between the base of the Pyrenees and the Maritime Alps, and are very poor in species throughout Italy and Sardinia. They are absent from almost the whole of northern Africa, the Mediterranean islands (except Sardinia), the whole Balkan district, the Crimea, Caucasus, and western Asia.1 The uniformity of the fresh-water fauna is disturbed only in the extreme south. 4, 40 Sesara . 3 Geostilbia. . 8 Vivipara 4 Solenaia 1 Trochomorpha 5 Succinea . .11 # Valvata 1 Cyrena: 7. 13 Trochomorphoides 1 Lithotis 2 Ampullaria 4 Sphaerium . 1 Parmacella (?) . 1 Vaginula . 1 Assiminea 9 Pisidium . . 5 Tebennophorus. 1 Camptonyx 1 Acmella 2 WMelonita™. .. 2 Anadenus . 4 Coelostele 1 Pomatias . 4 Tanysiphon . 1 Plectopylis . .11 Carychium 3 Diplommatina 63 Novaculina . 1 Plectotropis . 3 Ancylus i ePipina . ~. -.. 1 = Nausttora 1 The Cingalese district, which almost approaches the character of a distinct province, presents several remarkable points of dissimilarity from the rest of India. It consists of the island of Ceylon, and of a portion of S. India whose exact limits have yet to be defined. It appears, however, that the Western or Malabar coast, with the hills parallel to it, is more akin to Ceylon than the Eastern or Coromandel coast. The Travancore, Malabar, and S. Canara districts, with the Palnai, Anamalai, and Nilghiri Hills, are markedly Cingalese, while there seems to be no distinct evidence of similar relationship on the part of the Madras or even the Cuddalore district. Among the principal features of the Cingalese district is the occurrence of three peculiar genera of Helix, one (Acavus) large and finely coloured, another (Corilla) smaller, with a singularly toothed aperture. While the Corilla group shows relations with Plectopylis and other Burmese and Siamese sub-genera Acavus (Fig. 204) is totally distinct from any other Indian form, and shows signs of close relationship, in the great size of the embryonic shell, to the Helices of Madagascar (p. 335). In Ceylon the group is entirely isolated, and its occurrence, besides 304 CEYLON AND SOUTHERN INDIA CHAP. decisively separating that island from India, Burmah, and Siam, forms a most interesting problem in the history of dis- ‘tribution. Hurystoma, with a single species (H. vittata Miull.), is also peculiar. As usual when Helix gains ascendancy, the Naninidae retro- gress. Durgella, Austenia, and Girasia are absent altogether, while Macrochlamys, Sitala, Kaliella, etc., are present in greatly diminished numbers. The sub-genus Beddomea is peculiar, a form directly related to Amphidromus (Siam and Malacca). The fresh-water operculate Philopotamis is peculiar, but for one Fic. 204.— Helix (Aca- vus) Waltoni Reeve, Ceylon, showing em- bryonic shell (emb). 2 X F. species found in Sumatra; while Zanalia is quite peculiar. But the forms which, next to the Helices, most emphasise the separa- tion of the Cingalese district are the land operculates. There are eleven genera or subgenera of land operculates which do not occur in the rest of India proper. Two (Aulopoma and Cataulus) are quite peculiar, while the other nine are represented in Burmah, Siam, and the Malay islands, but not in India. On the other hand, Diplommatina and Alycaeus, so profusely abun- dant in India, have not yet been discovered in Ceylon. Among the slugs, Tennentia is a peculiar genus, whose nearest relation occurs in the Seychelles. Genera and Subgenera occurring in the Cingalese District, but not in N. and Central India Streptaxis Beddomea Craspedotropis Mychopoma Tennentia Philopotamis Pterocyclus Cataulus Acavus Tanalia Aulopoma Nicida Eurystoma Theobaldius Ditropis Opisthostoma Corilla Leptopomoides Cyathopoma The district consisting of Upper Burmah, Pegu, Tenasserim, x UPPER BURMAH AND PEGU 305 and Aracan, while essentially a part of the Indian province, contains several Siamese genera which are not found in India proper, as well as several which are at present peculiar. Amongst the former category are, of Helicidae, a single repre- sentative each of the genera Camaena (Siamese and Chinese) and Aegista (Chinese). Influence of the same kind is seen in the increased numbers of Plectopylis (14 sp.) and Plectotropis (5 sp.), of Clausilia (10 sp.) and Amphidromus (5 sp.), and of the large tubed operculates (11 sp. in all). Sesara and Sophina among the Naninidae are strange to India, while Hyalimaz is common only to the Andamans, Nicobars, and Mascarene Is. Hypselostoma (Fig. 202, A) is a most remarkable - genus of the Pupidae, reminding one of Anostoma of the New World. It is peculiar to the peninsula, but for one species in the Philippines. Among the Pupinidae, we have the peculiar Raphaulus and Hybocystis (Fig. 205), a very remarkable form, ae of which another species occurs at Perak. Two eee Helicina mark the most westward extension of | Bens. Young the genus on the mainland. In the extreme ed: north of Upper Burmah, Indian and Chinese forms intermingle. The Burmese district, together with the Indian and Siamese provinces, is pre-eminently the home of a group of Mollusca, originally of marine origin, which have permanently habituated themselves to a brackish or fresh-water existence. They belong to widely different families, and even Orders. Besides Cremno- conchus mentioned above, we have, among the bivalves, Vovacu- lina, a Solen living in fresh water in the Ganges, Irawadi, and Tenasserim estuaries; Scaphula, an Arca, one species of which occurs in the Ganges hundreds of miles above the tideway (see Fig. 9, p. 14); and Martesia, a Pholas from the Irawadi Delta. Clea (which also occurs in Java and Sumatra) is probably an estuarine Cominella; a Tectura has earned the name fluminalis from its exclusive residence in the Irawadi R.; Jravadia is probably a Rissoina of similar habits, occurring from Ceylon round to Hong-Kong; Brotia is a Cerithium from an affluent of the River Salwin, and Canidia is a Nassa, occurring in the embouchures of rivers from India to Borneo. Nowhere else in the world is there such a collection — not exhausted by this list VOL, III x 300 THE ANDAMANS AND NICOBARS CHAP. —of marine forms caught in process of habituation to a fresh- water or even a land existence. The Andaman and Nicobar Islands possess no peculiar features in their land Mollusca. They are closely related to the adjacent coasts of Lower Burmah. Amphidromus (2 sp.) occurs in the Andamans alone, and Clausilia (2 sp.) in the Nicobars alone, while Hyalimax occurs in both groups. A remarkable Helix (codonodes Fér.) from the Nicobars appears to find its nearest relations in the isolated group from Busuanga and Min- doro (p. 815). Land operculates are abundant, in the Nicobars actually outnumbering the pulmonates (28 to 22). Helicina and Omphalotropis, genera characteristic of small islands, are found on both groups. (6) The Siamese Province includes the area occupied by the districts known as Siam, Laos, Cambodia, Cochin China, Annam, and Tonquin. Along the whole of its northern frontier, the zoological is no more than a political boundary, while on the east the mountain ranges which part Siam from Pegu and Tenasserim are not of sufficient height to offer any effective barrier to distribution. The province is accordingly qualified to a considerable extent by Indian and Chinese elements. Streptaxis is, but for three Hnnea, the sole representative of the carnivorous genera, and attains its maximum in the Old World. Partly owing to Chinese influence, the Helicidae, with 11 genera and 46 species, begin to regain their position as com- pared with the Naninidae (12 genera, 54 species). Of the Helicidae, Acusta and Hadra appear now for the first time, and, with Plectotropis, Stegodera, and Clausilia, form a marked Chinese element. Amphidromus, with 33 species, is the most char- acteristic land pulmonate. Several genera, whose nucleus of distribu- tion lies among the islands farther east, appear to have penetrated as far as these coasts. Such are Chlo- ritis, Camaena, and Obbina among pee the Helicidae, Zrochomorpha, and, Fic. 206.— Cyclophorus siamensis of the operculates, Helicina. Bork) Siaey Land operculates are very richly developed, In all, there are 17 genera and 104 species x SIAM AND CAMBODIA 307 known. The tubed operculates attain their maximum, and Cyclophorus is even more abundant than in India. Fresh-water bivalves abound. Dipsas and Pseudodon are common to China, and Unio and Anodonta are profusely represented. A curious resemblance to S. America appears in this group, a single Mycetopus occurring, the only species not Brazilian, while Arconaia appears very closely to approach the Hyria of the same locality. Several genera of the Hydrobia type (Pachy- drobia, Jullienia, Chlorostracia) are peculiar. Land and Fresh-water Mollusca of the Siamese Province Streptaxis . . 20 Chloritis 8 Faunus 1 Leptopoma . 10 Pamears . . . 3 Doreasia . 1 Bithynia 9 Lagochilus 6 Helicarion 7 Camaena . 5 Wattebledia . 1 Pupina Tris) Microcystis ® Hadra . 5 Stenothyra 4 Hybocystis . 3 Sesara (?) . 1 Obbina 1 MHydrobia . 1 Alycaeus. 6 Medyla 1 Amphidromus 33 Pachydrobia. 9 Cataulus(?). 1 Xesta . 4 Bocourtia. . 2 Jullienia 6 Diplommatina 2 Macrochlamys . 6 Buliminus. . 4 Lacunopsis 6 Helicina . 4 Kaliella 5 Hypselostoma 2 Chlorostracia. 4 Georissa. . 2 Hyalinia (?) . 1. ‘Yonkinia . . 1 Vivipara .. 39 Modiola (f. w.) 2 Hemiplecta 14 Clausilia . 15 Valvata 1 Dreissensia . 3 Rhysota 2 Opeas . 7 Ampullaria . 15 Anodonta. . 17 Trochomorpha 6 Spiraxis(?) . 2 Assiminea. 7 Mycetopus . 1 Trochomorphoides 3 Subulina . 1 Procyclotus 6 Pseudodon . 18 Plectopylis 5. Succinea.. 4 jDasytherium. 2 Dipsas .. 4 Stegodera . 2 WVaginula . . 7 Opisthoporus. 5 Unio . 64 Plectotropis . 12 Limnaea . . 7 Rhiostoma 7 Arconaia . t Trachia 3 Planorbis . 6 Myxostoma 1 Cyrena 6 Fruticicola 2 Canidia 138 Pterocyclus 7 Batissa et: Acusta . 2 Melania 39 Cyclophorus . 28 Corbicula . 35 (c) The Malay Province includes the peninsula of Malacca south of Tenasserim, and the series of islands beginning with Sumatra and stretching eastward up to the Ké Is., besides Borneo and Celebes. The Philippines form a separate province. The Malay province is singularly poor in representative forms, whether we regard it as a whole or consider the islands separately. Nota single genus, with the exception of Rhodina (Malacca), appears to be peculiar. The contrast with the West Indies is in this respect very striking. Java, for instance, which is well explored, and almost exactly eleven times the size of Jamaica, has about 100 species of land Mollusca, while Jamaica has about 460. 308 MALACCA — SUMATRA CHAP. This want of individuality in the land Mollusca of the Malay islands is accounted for by a consideration of the sea depths which separate them from the Asiatic mainland. The accom- panying map, the red line on which is intended to show what would be the result of an elevation of the sea bottom for no greater amount than 100 fathoms, exhibits clearly the fact that these islands are practically a part of Asia, a large stretch of very shallow sea extending between Siam and the greater part of the north-west coast of Borneo. In all probability the three great islands of Sumatra, Java, and Borneo were united with the mainland of Asia, and with one another, at a period, geologically speaking, com- paratively recent. This follows from the general uniformity of their land Mollusca, both as regards one another and as regards the mainland. Nor do the smaller mem- bers of the island series — Bali, Lombok, Sumbawa, Flores, Timor, and Timor Laut — show any marked individuality in the possession of peculiar genera. Wallace’s line is absolutely non-existent, so far as Z the land Mollusca are concerned. ‘The Fre. 207.— Ariophanta Rum- really noticeable break in distribution BRS Na ERS TANS comes with the Aru Is., for while the Tenimber group (Timor Laut, etc.) are decidedly Malay, and. the Ké Is., in the poverty of our information, uncertain, the Aru Is. are aS Papuan as New Guinea itself. The profound depths of the Banda Sea to the north, and the Timor Sea to the south, appear to have kept the islands from Flores to Timor Laut free from the intrusion of any Moluccan or any considerable Australian element. The Moluccas, as has been already remarked, besides possessing considerable peculiarities of their own, unite a mixture of the Malay and Papuan elements, and serve as a sort of debatable ground for the meeting of the two. The Malay peninsula is practically another island of some- what the same shape and general trend as Sumatra, and about one-half the size. Its general relations —and the remark applies to the great Sunda Islands as well—appear to be rather more with Burmah, Tenasserim, and even the Cingalese district, than with Siam. Points of connexion between Ceylon and Sumatra, and Ceylon and Borneo, have already (p. 804) been brought out. Yff he Ujpjyypfyyyyy Yi JiuAJj jy , TAVA AND RORNEO 309 ind ave yer- Lps, 180 135 a | ong | ara- | Map to illustrate the lo 1 to GEOGRAPHICAL DISTRIBUTION ava of the Land Mollusca of the am >] EAST INDIAN ARCHIPELAGO pre- The red line marks the 100 fathom line English Miles {@_9 80 190 150 290 250 390 250 490 450 | = ————— = 22 t stoma smith, istho- L0sum Both has c1eS Ss as rion, »pre- idant ir on prac- se of is far | case ~ trom China, on the mainland of Asia, Australia, or AITICa, Map B. Between pages B08 and G09. 95 100 105 no 15 120 Saal = —— = = a —— TS Freie i 7000, to 2000 fathoms | | f | * Patan I? 4 : i Map to illustrate the ae e B. ESO GEOGRAPHICAL DISTRIBUTION | e > of the Land Mollusca of the A _ EAST INDIAN ARCHIPELAGO je gS | The red line marks the 100 fathom, line a | English Miles eo a @_9 59 190 igo 290 250 890 250 490 450 + ta ai : Ss al ae Luban \ AYA Ki 2000 2) 3% i fol SO00-LOO VA v 0 2000 |to 2000 : wo \ eet) fathoms YDAWNAO z . Pelew I? ) a 500 Balambangan op SBA J 2 : ) s|L ow “ SZiasilan AY o t lace Soolo0 y) : 00 Tah Taw = Ci 5 ae 2000 , homs $ ue Of t8 Sanghir gol ; aa oma 2000 . : Talnutse I!) ¢ fathoms |" ty fo ae “ 2000 Sy Lp S582 ee. =e A Terma GIO) fathoms i s as By aoe (SS . Waifs ine? q ‘ se my BaWWsEOY, ae ashen CELEB HE ON Kier a oN NGS BS p P 4 Below 700 fathoms 8000 fathoms rey fen ri @ | Timor (Le B) 0. 32 34 ioe 100! s RY London: Mucunllan & Co, ni x JAVA AND BORNEO 309 It seems not impossible, from the point of view of the land Mollusca only, that the Sunda Islands may at one time have stretched much farther into the Bay of Bengal, prolonged, per- haps, into what are now the Andaman and Nicobar groups, while Ceylon and the western side of the Deccan, united into one continuous piece of land, and possibly separated from N. India by a wide stretch of sea, extended farther eastward in a long island, or series of islands. Java, from its Mollusca, does not appear to hold the compara- tively isolated position which its mammals and birds seem to indicate. Borneo, on the other hand, is more Siamese than Java or Sumatra in respect of a group whose metropolis is Siam, namely, the tubed operculates; for while that section is repre- sented by 3 species in Sumatra and only 2 in Java, in Borneo it has as many as 19, FKhiostoma not occurring in the two former islands atall. Alycaeus, Lagochilus, Pupina, and Cyclophorus are found throughout, but Hybocystis (Malacca, 1 sp.) does not quit the mainland. Borneo is remarkably rich in land operculates, especially noticeable being the occurrence (11 sp.) of Opisthostoma (Fig. 208), a most extraordinary form of land shell (Ceylon, Siam), of Diplommatina (17 sp.), and Raphaulus. The occurrence Fic. 208.—A, Opisthostoma of a single Papuina (Moluccas eastward) Cookei E. A. Smith, is very remarkable. Borneo; B, Opistho- A : ants? stoma grandispinosum Amphidromus is a genus characteristic G.-A., Borneo. Both of the great Sunda Islands, attaining its *® maximum in Java (12 sp.). The Indian Glessula still has one species each in Sumatra, Java, and Borneo. One species of Streptaxis! occurs in Malacca, but Hnnea (8 sp.) reaches as far east as Borneo and the Philippines. Parmarion, Helicarion, Ariophanta, and other groups of the Naninidae are well repre- 1 Streptaxisisaremarkable instance of amainlandgenus. Althoughabundant in the Oriental, Ethiopian, and Neotropical regions, it never seems to occur on any of the adjacent islands, except in the case of Trinidad (1 sp.), which is prac- tically mainland. Omphalotropis, on the other hand, is the exact reverse of Streptaxis in this respect, occurring all over Polynesia and the Malay Is., as far west as Borneo, as well as on the Mascarenes, but never, save in a doubtful case from China, on the mainland of Asia, Australia, or Africa, 310 CELEBES Crane sented. Hemiplecta and Xesta are abundant and large, while the Rhysota of Borneo contain some huge sinis- — tral forms. hodina is a remarkable form from Malacca, whose exact generic position is not yet settled. Clauszlia has afew species on all the islands, the last occurring on Ternate, and a single Papuina (Moluccas and N. Guinea) occurs in Borneo. The Island of Celebes marks the be- ginning of a distinct decrease in the Indo- Malay element. The Naninidae lose an eround, in proportion to the Helicidae, Frc. 209.— Amphidromus Macrochlamys, for instance, being repre- perversus L., Java. | sented by only one species, and Hemiplecta by four. Other characteristic genera of the Indian region dwindle, such as Amphidromus, Clausilia, the tubed operculates, and Cyclophorus, while Sitala, Kaliella, Glessula, and Plectotropis disappear altogether. Comparing the total numbers of Naninidae and Helicidae from Sumatra to New Guinea, we obtain this interesting result : — Sumatra Java Borneo Celebes Moluccas N. Guinea Nanina (all genera) 26 32 51 22 36 40 Helix (all genera) 7 11 13 14 55 91 It will be noticed that the proportion of Naninidae to Helicidae, which has been nearly 4 to 1 in Sumatra, falls to 3 to 1 in Java, and rises again to 4 to 1 in Borneo (showing the essentially con- tinental character of the island) ; in Celebes it further falls to 3 to 2, while in the Moluccas the scale turns and Helix has the advantage by about 8 to 5, and in N. Guinea by more than 2 to I. There is the same absence of marked features of individuality in Celebes as in the islands dealt with above. Not a single genus is peculiar. The nature of the sea bottom between Borneo and Celebes, with its indications of a somewhat broad bridge over an otherwise deep channel of separation, would seem to account for and suggest the true explanation of the facts as they stand. At the same time, there are indications of a certain amount of contrast between N.and 8. Celebes. The Indian element, which constitutes the preponderating majority of the fauna, is common to north and south alike. But the north part of the island, in x CELEBES — THE MOLUCCAS 311 which Obda and Obdina occur, shows decided relationship with the Philippines, while the occurrence of three Chloritis and one Planispira tend to approximate S. Celebes rather with the Moluccas. The islands eastward of Java, from Bali to Timor Laut and the Tenimber Is., present no trace of individual peculiarities ; they simply carry on the Indo-Malay fauna as though along a great peninsula. Even Timor, surrounded as it is onall sides by sea of profound depth, shows no sign of possessing even one peculiar genus. Amphidromus, perhaps the most characteristic of all Indo-Malay genera, occurs throughout, diminishing in numbers as we go eastward (Bali, Lombok, and Sumbawa 4 sp., Timor 2 sp., Timor Laut 1 sp.), while Plectotropis reaches no farther than Flores and Timor. The tubed operculates are alto- gether wanting. In Timor Laut we have Moluccan influence appearing in 3 Chloritis, and there is one (supposed) Corasza. Two Helices of a marked Australian type (Rhagada) occur, one in Flores, the other on Dama I., south-west of Timor. The con- ficuration of the sea bottom (see map) would lead us to believe that the north-west coast of Australia once stretched a good deal nearer to these islands. The Moluccas, taken as a whole, constitute a transition region between the Indo-Malay and the Papuan faunas, uniting, to a very considerable extent, the features of both. They fall into two well-defined groups. The northern, or Ternate group, consists of Gilolo (Halmahera), Batchian, and the outlying islands as far south as and including Obi major. The southern, or Amboyna group, consists of Buru, Ceram, Amboyna, and the chain of islands to the south-east of Ceram, as far as, and including the Ké Is. The Ternate group shows decidedly closer relations with New Guinea than the Amboyna group. Thus, among the Helices, the markedly Papuan genus Papuina is represented by 7 species in the Ternate group, but by 1 in the Amboyna group. Again, the Cristigibba section of Planispira, which is a Papuan form, has 4 representatives in the northern group, but only 1 in the southern. Certain points of connexion with Celebes come out in the southern group which are wanting in the northern; thus of Chloritis there are 8 species in Amboyna, 0 in Ternate, 3 in Celebes. In the Moluccas the Helicidae, for the first time as we move “312 THE MOLUCCAS CHAP. eastward from India, gain the ascendancy over the Naninidae, the numbers being, Helix 55, Nanina 36. If we take the groups separately, we find that in the Amboyna group the proportion is 22 to 23, while in the Ternate group it is 33 to 18, an addi- tional proof that the Amboyna group is far less Papuan than the Ternate. Of Planispira, the most characteristic sub-genus of Helix, there are 12 species in the Ternate group, and 5 in the Amboyna. The section Phania, which contains 4 species of the finest Helices known, is quite peculiar to the Ternate group. One species of Obbina, a sub-genus markedly Philippine, occurs in each group. Several of the Indo-Malay land operculates (e.g. Ditropis) reach their limit here, and here too we have the last Clausilia (strangely absent from the Amboyna group). Amphidromus is not reported on sufficient authority to warrant its insertion in the list. Land Mollusca of the Moluccas. (T =Ternate, A = Amboyna! group) Helicarion . 1A _ Cristigibba . 1A,42° “Paunus eee pA Kuplecta. . LA Obbina .«. LA; 12)? Mivipara eee 1A Mesta: go. 24, (OA Pama iia 4T.. Acmella, 2 See 1A Macrochlamys ij Ae) cAllbersia: +. 3T Diplommatina. 4A,2T Lamprocystis 4A,2T Camaena . 1T Registoma . . i Macrocycloides 4A . Papuina . . 1A,72° Pupmellageae 1A Sitala .°0.,7). TA: pero aene ie SA. -Callia see 2A Kaliella, 2 ti 23a 1 Vertigo g nee 2A lLeptopoma. . 4A,5T Trochomorpha 3A,37T Clausilia. . 1T. Lagochilus 2-2 ft Agee Endodonta . LA _Opeas . . 44,47 Ditropseee 3A Pabula ene. 1A Subulina. . 1A . Cyclotus ~)) 2) Agme Plectotropis . 1T Tornatellina 1A Omphalotropis 3A Eulota .. 1A Vaginula =. LA, , Georissa: 2 a iT Chloritis. . 8A Melania . . I8A,4T. Helicna. > 252. Planhispira . oA, 120 tate (d) The Philippine Province. —In the extraordinarily rich development of their Mollusca, the Philippines form a remark- able contrast with the poverty of the adjacent Malay islands. No less than 727 species of land Mollusca alone are known from the group, amongst which are included some of the finest and handsomest forms yet discovered. ‘The main features of the fauna are Indo-Malay, with the addition of a certain Australa- 1The Amboyna group has been much the better explored. Common to both groups are‘one sp. each of Kaliella, Trochomorpha, Opeas, Leptopoma, Cyclotus, Helicina. x THE. PHILIPPINES 313 sian element, and a remarkable development of individual char- acteristics. The principal indigenous feature is the profuse abundance of the genus Cochlostyla, a group of large and elegant land shells, partly helicoid, partly bulimoid in shape, many of the species of which are covered with a curious hydrophanous epidermis. They are in the main of arboreal habits, living in the tops of the enormous forests which cover the greater part of the islands. As many as 247 species, belonging to 15 sub-genera, have been described. | The distribution of the sub-genera of Cochlostyla on the Fic. 210. — Cochlostyla (Chry- Fic. 211.— Cochlostyla (Ortho- salis) mindoroensis Brod., stylus) Portei Reeve, Luzon. Mindoro, Philippines. Xx 3. different islands of the Philippine group affords important evidence on the geological relation of the islands to one another. Thus we find Orthostylus and Hypselostyla occurring in the central islands and 8S. Luzon, but not in Mindanao or Mindoro; we find Chrysalis peculiar to Mindoro, Prochilus to Mindoro and the Cuyos, Ptychostyla to Luban, all these being sub-genera of very marked characteristics. Six out of the fifteen sub-genera are entirely absent from Mindanao, although occurring on the islands in the immediate vicinity. The little group Tablas- Romblon-Sibuyan are entirely deficient in certain sub-genera which occur on the islands surrounding them on all sides. 1 A. H. Cooke, P. Z. §. 1892, pp. 447-469. 314 THE PHILIPPINES CHAP. Other forms peculiar to the Philippines are Diaphora, a section of Hnnea with a curi- ously produced mouth, and several sub-genera of the Naninidae ( Vitriniconus, Vit- rinoidea, Hemitrichia). ‘The great Ehysota here find their metropolis. Another very marked group of Helix is Fic. 212. — Helix (Obbina) rota Brod., Obbina, 19 of the 25 known Philippines. : d : species being peculiar. The Helicidae proper of the Philippines are still held in check, as in the greater part of the Indian region, by the Naninidae. The single Trachia and Plectotropis, and the 2 species each of Plectopylis and Satsuma, indicate affinities with Indo-China. Further important Indian relationships are seen in the great Nanina and Cyclophorus, which here attain almost Indian dimensions; in Kaltella (8 sp.), Si ‘tala’ (2), Clausilia (1). Among the operculates we still have 1 Alycaeus and 1 Coptochilus. Singularly enough, several Indian genera which occur here are not found in the intervening islands of Bor- neo, Sumatra, or Java, e.g. Streptaxis, Hypselostoma, Ditropis, Aecmella, and Cyathopoma. ‘The curiously tubed Malay opercu- lates, Opisthoporus, etc., fail to reach the Philippines proper, although occurring in Borneo and N. Celebes; one of them reaches Palawan. The strikingly Malay genus Amphidromus reaches Palawan, but no farther (1 sp.), while 2 species reach Mindanao, and one of these penetrates as far as Bohol and S. Leyte. Amongst the slugs, Mariaella occurs again only in the Seychelles, and Tennentia only in Ceylon. Land and Fresh-water Mollusca of the Philippines Streptaxis . . 1 Hemiplecta .11 Trochomorpha 21 Papuina 1 Ennea . . .10 Hemitrichia .15 Endodonta 1 Phoenicobius . 7 Mariaella . . 38 Xesta .. . 2 Plectopylis 3 Cochlostyla. 247 Tennentia . . 1 Macrochlamys 5 _ Plectotropis 1 Amphidromus. 2 Helicarion . . 21 Microcystis 3 Aulacospira 3 Hapalus (?) 4 Vitrinopsis . 5 Lamprocystis . 17 Pupisoma 1 Hypselostoma. 1 Vitrinoidea . 1 Bensonia 4 Satsuma 2 Pupa 4 Rhysota . .17 Vitriniconus . 16 Torcasia 2 Clausilia 1 Trochonanina 2 Sitala 2 Chloritis . 7 Subulina 3 Euplecta . . 28 Kaliella 8 Obbina . . 19 Prosopeas 2 7.4 ISLANDS ADJACENT TO THE PHILIPPINES 315 Opeas 4 Melania 50 Hargreavesia . 1 Cyathopoma . 5 Geostilbia . /° Pirena, . 2 Callia 2 Cyclotus .,'. 19 Tornalellina 1 Bithynia 1 Pupinella . .. 3 Omphalotropis 3 Succinea 38 Vivipara 7 Helicomorpha 4 Helicina . . 18 Vaginula 2 Ampullaria 5 Coptochilus £ Geortssa Ayt 38 Ancylus 1 Acmella 2 Alycaeus 1 Limnaea 3 Diplommatina 41 Leptopoma . 42 Anodonta . . 1 Planorbis . oe, Arinia . 6 Lagochilus-. 7. If “Cyrena's 2. 3 Physa 2 Pupina . 5 Cyclophorus . 381 Corbicula . . 7 Registoma . CeiKOpIse | 6. 0er Islands adjacent to the Philippines.— The Philippines are connected with Borneo by two distinct ridges or banks of eleva- tion, which enclose between them the Soo-loo or Mindoro Sea. There can be little doubt that these ridges represent the ancient highway of transit, by which Indo-Malay species passed into the Philippines. The depth of the sea on either side is profound, ranging from an average of about 1000 fathoms west of Palawan to 2550 off the south-west coast of Mindanao. It appears that the fauna of the Soo-loo ridge is definitely Philippine up to and including Bongao, Sibutu, and Bilatan, the last islands at the Bornean end of the ridge. On these are found two species of Cochlostyla and an Obbina. The Palawan ridge may also be described as more or less Philippine throughout. One species of Cochlostyla occurs on Balabac, just. north of Borneo, and two on Palawan, but these are perhaps counterbalanced by the definitely Indo-Malay Amphi- dromus and Opisthoporus (1 sp. each). At the northern end of the ridge, on Busuanga and Calamian, the Philippine element predominates. Representatives of two remarkable groups of Helix ( Camaena and Phoenicobius) occur along the Palawan ridge and in Mindoro. The Phoenicobius find their nearest allies in the curious small group known as Obda, from N. Celebes, the Camaena possibly in a type of Helix (Hadra) occurring in New Guinea and N.E. Australia. The only other Helix from the whole of the E. Indies which bears any resemblance to the Phoenicobius group is H. codonodes Pfr., which is peculiar to the Nicobars. A few forms assigned to Camaena also occur in Further India and Siam. It would appear possible, therefore, that these two isolated groups are a sort of survival of a fauna which perhaps had once a much more extended range. 316 CHINA CHAP, (2) The Chinese Sub-region. — The Chinese Sub-region in- cludes the whole of China from its southern frontier up to and including the basin of the Blue or Yang-tse River, together with the coast district, including Corea, perhaps as far north as Vladi- vostok, and the outlying islands of Hainan, Formosa, the Loo- Choo and Bonin groups, and Japan to the north of Niphon. It may be divided into two provinces, the Chinese and the Japanese. (a) The fauna of the Chinese province proper bears, in many respects, strong marks of relationship to that of India and Siam. Thus Streptaxis, Helicarion, Macrochlamys, Kaliella, Sitala, Ario- phanta, Rhysota, Hemiplecta, Diplommatina, Opisthoporus, Ptero- cyclus, Lagochilus, and Alycaeus all occur, especially in Southern China. The two points in which the sub-region bears special marks of individuality are Helix and Clausilia. The sub-genera of Helix which have their metropolis in China are Satswma, Cathaica, Aegista, Acusta, Huhadra, Plectotropis, and Plectopylis. Sinistral forms (compare Fig. 218) are rather prevalent. In several cases —e.g. Trichia Gonostoma Fruticicola—there is a reappearance of forms which appear to belong to well-known European sub-genera. Clausilia here attains a kind of second centre of distribution, and is represented by its finest forms, which belong to several peculiar sub-genera. The carnivorous Mol- lusca are not abundant, and are rep- resented by Rathowisia (a peculiar genus of naked slug), Hnnea, and Streptaxis. In the western provinces Buliminus is abundant in several Fig. 213. — Helix (Camaena) cica- Sub-genera, one of which appears to EOSOSEN NM og CHEE be the European Mapaeus. There is little which is striking in the operculates, which are most abundant in the south, and appear to be mainly derived from Indian and Siamese sources. The occurrence of Helicina (3 sp.), Omphalotropis (1), Leptopoma (2), and Realia (2), is evidence of some influence from the far East. Heudeza is a very remarkable and quite peculiar form of Helicina with internal plicae, perhaps akin to the Central American Ceres. Fresh-water genera are exceedingly abundant, especially Melania, Unio, and Anodonta. The occurrence of Mycetopus (a South-American genus) is remarkable. There are several x - CHINA, HAINAN, FORMOSA, AND COREA 317 peculiar forms of fresh-water operculates, whose exact position is hardly yet assured. Land and Fresh-water Mollusca of the Chinese Province Rathouisia. . 1 Trichia. . .10 Succinea 8 Leptopoma. 2 Streptaxis . . 7 Cathaica . . 22 Vaginula . 7. Lagochilus-..... 10 Bnnea . . .12 Aegista. . . 10 Limnaea 2 Cyclophorus . 18 Parmarion. . 2 Armandia . . 3 Planorbis 6 Coelopoma . 1 Helicarion. . 15 Acusta . . .15 Melania. 44 Pterocyclus 3 Puplecta . . S Obbina . . . 1 Paludomus 3 Opisthoporus . 4 Macrochlamys 19 Camaena . . 5 Bithynia 12 Cyclotus . . 10 Microcystina . 2 Euhadra . .14 Lithoglyphus. 3 Scabrina .. 4 Microcystis 7 Plectopylis. .19 Melantho(?) . 1 Ptychopoma . 12 Kaliella. . .16 Stegodera . . 6 Pachydrobia 1 Omphalotropis 1 Sitala 8 Chloritis . . 1 Prososthenia . 2 Realia 2 Ariophanta 1 Hel. Inc. sed. . 39 Stenothyra. . 2 Pseudopomatias 1 Rhysota. 5 Buliminus. . 21 MHydrobia . 2 Helicina. 3 Hemiplecta 1 Buliminopsis . 3 Mecongia 1 Georissa. 4 Trochomorpha 2 Buliminidius . 3 Oncomelania . 9 MHeudeia. 1 Limax 1 Napaeus . . 14 Margaracya 1 Cyclas a el Philomycus 1 Rachis(?). . 4 Rivularia 4 Corbicula . . 50 Patula 2 Pupa .. .10 Delavaya jean 0) 18 ie ea Baul 5S: Gonostoma. 4 Clausilia . 102 Fenouillia . 1 Monocondylaea 1 Metodontia 2 Opeas . . .12 Vivipara 34 Anodonta . . 55 Vallonia 1 Euspiraxis. . 1 Diplommatina 20 Mycetopus. . 12 ilecctotropis . 9 Subulina . . 5 Pupina . . . 6 Pseudodon. . 1 Fruticicola .11 Stenogyra(?). 12 Alycaeus . . 23 Dipsas . . . 4 Satsuma . 14 The island of Hainan, in the extreme south of the sub- region, has 40 species of Mollusca, 22 of which are peculiar, but there is no peculiar genus. The Mollusca of Formosa, although in many cases specifically distinct, show close generic relationship with those of China. The characteristic Chinese groups of Helix and Clausilia occur, and there is still a considerable Indian element in several species of Streptazis, Macrochlamys, Kaliella, and Alycaeus. The oc- currence of two Amphidromus, a genus which, though Siamese, is not found in China or Hainan, is remarkable. The peninsula of Corea must undoubtedly be included in the Chinese sub-region. It is true that the land operculates scarcely occur, but there are still a number of Clauwsilia, and several of the characteristic Chinese groups of Helix are reproduced. In some points Corea appears to show more affinity to Japan than 318 JAPAN AND NEW GUINEA CHAP. to China, four of the Helices being specifically identical with those of Japan, but the peninsula is at present too little explored for any generalisations to be made as to its fauna in this respect. (6) Japanese Province. — Kobelt distinguishes four groups of Mollusca inhabiting Japan (a) circumpolar species, actually occurring in Europe, Siberia, or N. America, or represented by nearly allied species (these of course do not belong to the Japanese province as such); (6) Indo-tropical species; (¢) species which are Chinese or akin to Chinese; (d@) peculiar species, a mixture of two forms, southern and northern, the latter being chiefly Hyalinia, Patula, and Fruticicola. Out of a total of 193 Japanese species, at least 164 are peculiar. The Japanese Helices belong to sub-genera common to China (Plectotropis 8, Huhadra 21, Acusta 23?); but the Naninidae scarcely occur at all. The principal feature of the fauna is the development of Clausilia, which presents some extraordinarily fine forms. One slug (Philomycus) is identical _ with an Indian species. The operculates, which consist mainly of a few species each of Diplommatina, Cyclophorus, Pupinella, Pupina, Helicina, and Georissa, belong almost exclusively to the southern islands Kiu-siu, Sikoku, and southern Niphon. The three species usually reckoned as Japonia are probably forms of Lagochilus. C. The Australasian Region This region includes all the islands of the Pacific east of the Moluccas, and falls into three sub-regions —the Papuan, the Australian, and the Polynesian. 1. The Papuan Sub-region may be divided into — (a) the Papuan Province proper, which includes New Guinea, with the Aru Is. and Waigiou, the Admiralty Is.. New Ireland, New Britain, and the d’Entrecasteaux and Louisiade Groups; (0) the Queensland Province, or the strip of N.E. Australia from C. York to the Clarence R. (about 29° S. lat.); (e) the Melanesian Province, which includes the New Hebrides, New Caledonia, with the Loyalty Is. and the Viti Is. The Solomons form a transition district between the Papuan and Melanesian provinces, abounding on the one hand in characteristic Papuan Helices, while on the other they form the north-western limit of x NEW GUINEA 319 Placostylus, the group especially characteristic of the Melanesian province. (a) The Papuan Province.—The molluscan fauna of New Guinea is the richest and by far the most original of all the Australasian region. We find ourselves, almost in a moment, in a district full of new and peculiar forms. New Guinea may be regarded as the metropolis of the rich Helicidan fauna, which is also characteristic of the Moluccas to the west, of N. and N.E. Australiato the south and south-east,and of the Solomonsand other groups to the north-east. Here abound species of Papuina and Insularia (the latter being quite peculiar), among which are found, if not the largest, certainly the most finished forms of all existing Helices. Chloritis (18 sp.), Planispira (5), and Cristi- gibba (9) are common with the Moluccas, while a tropical Australian element is shown in Pedinogyra (1) and Hadra (4). Very remarkable, too, is the occurrence of one species of Obbina and Rhysota, genera which culminate in the Philippines and here find their most eastward extension; while asingle Corasza serves to form a link between the Corasza of the Philippines and those of the Solomon Is., if the latter are true Corasia. We naturally find considerable traces of a Polynesian element, which appears to be principally characteristic of the eastern part of the island. Most noteworthy in this respect is the occur- rence of Partula (8), Tornatellina (1), Charopa (1), Thalassia (3). As compared with the true Pulmonata, the operculates are feebly represented, and the great majority are of a markedly Polynesian type. Nota single Cyclophorus occurs; Lagochilus, Alycaeus, and all the tubed operculates, so marked a feature of the Indo-Malay fauna, are conspicuous by their absence, and the prevailing genera are Cyclotus, Helicina, and a number of sections of Pupina. Leptopoma, as in the Philippines, is strongly repre- sented. Not that an Indo-Malay element is altogether absent. We still have Xesta (5), Hemiplecta (8), and even Sttala (2), but the great predominance of Helix seems to have barred the progress, for the greater part, of the Indian Naninidae. The slugs appear to be represented by a solitary Vaginula. A single Perrieria is a very marked feature of union with Queensland, where the only other existing species (P. australis) occurs. The solitary Rhytida, so far the only representative of the carnivorous group of snails, emphasises this union still 320 NEW GUINEA AND ARU ISLANDS CHAP. further. Little is known of the fresh-water fauna. Melania (28 sp.) is predominant, but on the whole the relations are Australian rather than Indo-Malay. Ampullaria is wanting, while a decisive point of similarity is the occurrence of Lszdora (8 sp.), a genus entirely strange to the Oriental region, but markedly characteristic of the Australasian. Land and Fresh-water Mollusca of New Guinea Rhytida 1 Thalassia 2.) 3) (Calycia 4 Diplommatina 1 Helicarion 2 Ochthephila(?) 1 Partula 8 Pupimac eee Rhysota Ll) Chioritis’ 6.2)" 159) 2upa 1 Pupinellay] 33 Hemiplecta .11 Planispira. . 5 Stenogyra. 1 Omphalotropis 2 Xesta . 2 Cristigibba . 9 Tornatellina. 1 Bellardiella . 2 Microcystis . 38 Imnsularia. = iy | iBerneriay- 1 Leptopoma . 16 Microcystina. 2 Obbina. 1 Succinea . 1 Cyclotus” 3 32e75 Sitala . 2 Albersia 3 Vaginula . 1 Cyclotropis - 6 Oxytes (?) 2 Hadra. .. 4 + £zZ1imnaea . 2 Helicina, 295 Conulus 1 Pedinogyra 1: Asidora. 3 Unio 4 Trochomorpha 8 Papuina . . 85 Melania 28 Cyrena. 3 Nanina (?) 3 Corasia (?) 1 Faunus 1 Corbicula . I Charopa 1 Bulimus(?). 1 Vivipara . 4 Batissa. 8 Waigiow is practically a part of New Guinea. Twelve genera and twenty species of Mollusca are known, eight of the latter being peculiar. The occurrence of Papuina, Insularia, and Calycia sufficiently attest its Papuan relationship. Two species each of Albersia, Chloritis, and Planispira occur.} The Aru Js. are, as we should expect from their position, and particularly from the configuration of the adjacent sea bottom (see map), markedly Papuan. At the same time they show un- mistakable signs of long-continued separation from the parent island, for of their 36 land Mollusca 15, and of their 20 fresh- water Mollusca 9 are peculiar. The Papuan element consists in the presence of Papuina, Albersia, and Cristigibba. Moluccan influence is not absent, for the three Helicina, the Albersia, and one Cyclotus are all Moluccan species. The fresh-water fauna appears to be a mixture of varied elements. The single Segmentina is common to India, the Glaucomya to Malacca and the Philippines, while the single Batissa is also found in New Zealand. ' Mysol, with 2 Chloritis, 1 Insularia, 1 Cristigibba, is decidedly Papuan. x LOUISIADES AND SOLOMON ISLANDS 321 Land and Fresh-water Mollusca of the Aru Islands Xesta 4 Chloritis 5 Planorbis . 1 Cyclotus 3 Microcystis 1 Cristigibba 2 Segmentina 1 Helicina 3 Hyalinia (2?) . 1 Albersia 1 Melania . - 14 Cyrena . 2 Trochomorpha 1 Papuina 4 Leptopoma . 8 Glaucomya. 1 Patula i Pupa , 2 Moussonia . 1 Batissa . 1 Eulota . 1 Stenogyra . 2 Realia 1 The Louisiades, the d’Hntrecasteaux, and Trobriand Js., and Woodlark I., are closely related to New Guinea, containing no peculiar genera. Each group, however, contains a considerable proportion of peculiar species, an indication that their separation from New Guinea dates from a very distant period. From the Louisiades are known 34 species in all, 22 of which are peculiar. The fauna of the Admiralty Is., of New Hanover, and New Ireland is markedly Papuan, without any especial feature of distinction. The Admiralty Is. contain 15 sp. Papuina, 7 Chloritis, 1 Planispira, and 1 Corasia. A single Janella shows relationship with the New Hebrides and with New Zealand. In New Ireland Planispira (which is specially characteristic of W. New Guinea and the Moluccas) has disappeared, but there are 7 Papuina and 6 Chloritis. The essentially Polynesian Partula is present in both groups. The prominent feature of the Mollusca of the Solomon Js. is the extraordinary development of Papuina, which here cul- minates in a profusion of species and singularity of form. The genus is arboreal, crawling on the branches and attaching itself to the leaves of trees and underwood. Of the 140 land Pulmo- nata known from the group, no less than 50, or 36 per cent, are Papuina. Ten species of Corasia occur, but whether the shells so identified are generically identical with those of the Philip- pines, is not satisfactorily determined. Trochomorpha, with 22 species, here attains its maximum. Chloritis begins to fail, but still has 3 species. Indo-Malay influence still appears, though feebly, in Hemiplecta (3), Xesta (1), and possibly even Mae- rochlamys (1). The Rhytida, the 3 Hadra, and possibly the Paryphanta represent the Australian element. The growing numbers of Partula (13), the small and inconspicuous land operculates (only 22 in all, with Helicina very prominent), and the almost complete absence of fresh-water bivalves, show signs of strong Polynesian affinities. An especial link with the New VOL. III WY x 322 SOLOMON IS. AND QUEENSLAND | CHAP. Hebrides, New Caledonia, and the Viti Is. is the occurrence of Placostylus (16 sp.). It is very remarkable that this genus should occur in the Solomon Is. and not in New Ireland. The occurrence of Streptaxis, if authentic, is very noteworthy, the nearest species being from the Philippines. Land and Fresh-water Mollusca of the Solomon Islands Streptaxis (?). 1 Trochomorpha 22 Merope. . . 1 Pupina . 4 Rhytida 1 Nanina(?) . 2 Corasia(?) .10 Leptopoma. 4 Paryphanta (?) 1 Patula . . . 1 Placostylus . 16 Omphalotropis 2 Helicarion . 2 Thalassia . . 2 Partala;. . . 13 Cyeletus I Xesta 1 Chloritis . .-3 Succinea . . 1 Cyelotromice 2 Macrochlamys 1 Philina . . . 2 Melania. . . 18 MHeltemar 7 Hemiplecta 8 Hadra. . . 8 Diplommatina 2) Vnioe o Microcystis 2 Papua). .°50 (6) The Queensland Province. — The strip of coast-line from Cape York to the Clarence R. stands apart from the rest of Australia, and is closely connected with New Guinea. There can be little doubt that it has been colonised from the latter country, since an elevation of even 10 fathoms would create (see map) a wide bridge between the two. Many of the genera are quite strange to the rest of Australia. Land opercuiates are abundant, and of a Papuan type. Several of the characteristic Papuan genera of Helix (Papuina, Chloritis, Planispira) occur, Fic. 214.— Characteristic Aus- tralian Helices: A, F (Hadra) pomum Pfr.; B, a\ \ H. (Thersites) richmon- SG diana Pir. x 3. while Hadra attains its maximum. Panda, Pedinogyra, and Thersites are three remarkable groups in a rich Helix fauna. Parmacochlea is a peculiar form akin to Helicarion. The carniy- orous Mollusca are represented by Rhytida, Diplomphalus (New Caledonia), and Hlaea. One species of Janella, a slug peculiar to this region, occurs. The predominant fresh-water genus is Bulinus (Isidora). Ampullaria and Anodonta are entirely absent from Australia and New Zealand. x. QUEENSLAND AND NEW CALEDONIA 323 Land Mollusca of the Queensland Province Zealauu, is avuuualiv. The New Hebrides link New Caledonia and the Solomons by Map D.. Jb face page B22. N EW GUINEA AUSTRALIA CARPENTA aw PACIFIC OCEAN OF MAP to illustrate the relations THE LAND MOLLUSCA OF NEW GUINEA WITH THOSE OF NORTH AUSTRALIA. The red line marks the 100 fathom line ae ‘oy London: Macmillan & Co. Tendlon Stanford (aqg Fatale x QUEENSLAND AND NEW CALEDONIA 323 Land Mollusca of the Queensland Province Diplomphalus. 1 Macrocyclis (?) 1 Helix (inc.sed.) 6 Janella . dh mhyuda . .10 MHelicella . .10 SBulimus (?) 1 Georissa 1 Elaea 1 Planispira . . 8 Stenogyra . 1 Pupina . 16 Parmacochlea 1 Hadra .. . 51 Tornatellina 4 Hedleya. 1 Helicarion . @ /Chiorttis— <3, 5 “Pupa 3 Callia 1 Nanina . . 3 Pedinogyra 1 Vertigo . 4 Diplommatina 3 Hyalinia . .10 Thersites 1 Perrieria 1 Ditropis. 2 Thalassia 4 Papuina . . 6 Succinea 3 Dermatocera il Charopa 5 Panda 2 Vaginula 1 Helicina 8 Patula (?) . 4 (ec) The Melanesian Province includes those islands on which the remarkable group Placostylus occurs, the metropolis of whose distribution is New Caledonia. These islands are very possibly the remains of what was once a much wider extent of land. A single species of Placostylus occurs both on Lord Howe’s I. and in the North I. of New Zealand, but this fact, while highly interesting as indicating a possible former extension of land in a south-easterly direction, is hardly sufficient to bring these islands within the province as now limited. The Solomon Is., although containing Placostylus as far to the west as Faro L., form, as has been already stated, a transitional district to the Papuan province. New Caledonia. — The chief features of the Mollusca are the remarkable development of the helicoid carnivorous genera Rhytida (80 sp.) and Diplomphalus (18 sp.), 3 and of Placostylus (45 sp.). There is a stray Papuina, and a peculiar form Pseudopartula, but Helix has almost entirely disappeared. Polynesian influence is represented by Miecro- cystis (3 sp.), the so-called Patula (18 sp., many of which are probably Charopa), Torna- tellina (2 sp.), and Helicina (20 sp.). Partula does not reach So far south, but there are two species of Janella. ‘The recurrence of Mel- anopsis (19 sp.), absent from the whole Oriental region, is curious, and forms another link with New Zealand. The curious sinistral Limnaea Dc eee Csidora), common with Australia and New Pet., New Cale- Zealand, is abundant. eee The New Hebrides link New Caledonia and the Solomons by 324 THE FIJI 1S. AND SOUTH AND WEST AUSTRALIA CHAP. their possession of the typical heavy Placostylus (5 sp.) of the former, and the lighter and more elegant Charis (2 sp.) of the latter. There are 4 Papuina, and Partula is abundant (18 sp.), but there is no evidence at present that the carnivorous genera or the Melanopsis and Lsidora of New Caledonia occur. The Fiji Is., by the possession of 14 Placostylus of the Charis section, which is entirely absent from the adjacent Tonga group, form the eastern limit of the province. There appears to be only a single Partula, but the Polynesian element, especially as seen in Navicella (8 sp.), Neritina (20 sp.), Helicina (11 sp.), and Omphalotropis (11 sp.), is very strong. The Microcystis (9 sp.) and Trochomorpha (14 sp.) are also of a Polynesian type. (2) The Australian Sub-region includes the whole of Australia (with the exception of the Queensland province) and Tasmania, with New Zealand and the off-lying islands. The fauna, from the prevalence of desert, is scanty, especially in genera. Land operculates are almost entirely wanting. Limax is not indigenous, though several species have become natural- ised. The bulk of the fresh-water species belong to Lszdora, and it is doubtful whether Physa occurs at all. Unio has a few species, and also Vivipara, but neither Anodonta nor Ampullaria occur., There are a few Melania and Neritina. Tropical. South Australia. —'The Mollusca are scanty, and occur chiefly in the neighbourhood of the rivers, the soil being arid, with no shelter either of trees or rocks. Fresh-water species predominate, and the rich land fauna of Queensland is totally wanting. There are no land operculates, 6 Hadra, 1 Bulimus (?), 1 Stenogyra. West Australia. — Owing to the deserts which bound it, the Mollusca are very isolated, only one species being common with N.,5., and E. Australia. The chief characteristics are Liparus, a form intermediate between Helix and Bulimus, and, among the Hlelices, the group Rhagada. There are no slugs, no carnivorous snails, and only three land operculates. Land Mollusca of West Australia Lamprocystis. 1 Gonostoma 2 Hadra . . . 5 Cyclophomsia Hyalinia 1 Trachia. . . S Liparus. . .10 Hehcne eee Patula . 7 Xerophila . Li PUD « ieee ee Chloritis 2 Rhagada 8 /Suctings )) 79.03 x EAST AUSTRALIA, TASMANIA, AND NEW ZEALAND 325 In astern and Southern Australia (New South Wales, Victoria, and South Australia) the tropical element, so abundant in Queensland, almost entirely disappears, the last operculate (a ,Helicina) only reaching Port Macquarie, though several species of Helicarion occur in the extreme south. Hadra.is still abun- dant in New South Wales (18 sp.) and S. Australia (10 sp.), but becomes scarce in Victoria (2 sp.); New South Wales has also one Panda and two Thersites. Cystopelta is common with Tasmania, and one of the Janellidae (Aneitea) with Queensland. The carnivorous snails are represented by Rhytida. Caryodes, a bulimoid group perhaps akin to Ziparus, is common with Tasmania only. Tasmania. —. About 80 species of land Mollusca are known, not more than 10 being common with Australia. No land _ operculates occur; Hndodonta and Charopa are rare, and Hadra has entirely disappeared, but Pupa and Swuecinea occur. Car- hivorous genera are represented by Paryphanta, Rhytida, and _ Rhenea. Anoglyptais a peculiarsection of Helix, while Caryodes, _ Cystopelta, and Helicarion are common with Australia. Among the fresh-water Mollusca are a Gundlachia (see p. 845), and some forms of Amnicola or Hydrobia, one of which (Potamopyrgus) is common only with New Zealand.! i The Neozealanian Province.— The Mollusca of New Zealand, with the Kermadec, Chatham, and Auckland Is., are remarkably isolated. Such genera as Nanina, Partula, Pupa, Stenogyra, Succinea, Vaginula, Truncatella, Helicina, and Navicella, which might have been expected to occur, are entirely absent. The bulk of the land Mollusca are small and obscure forms, perhaps remains of a very early type, and appear to belong to the Zoni- tidae, neither Patula nor Helix occurring at all. The carnivorous forms are represented by Schizoglossa, a peculiar genus akin to Daudebardia, by Paryphanta, an extraordinary group of large shells with a thick leathery epidermis, and by Rhytida and Rhenea. In spite of its extreme isolation, the general relations of the fauna are partly with New Caledonia, partly with E. Australia. The occurrence of Placostylus has already been mentioned (p. 823), and three species of Janella, a genus which also occurs in Queensland and New Caledonia, indicate the same 1 See especially C. Hedley, Note on the Relation of the Land Mollusca of Tasmania and New Zealand, Ann. Mag. Nat. Hist. (6) xiii. p. 442. ; 3 26 POLYNESIA CHAP. affinity. Otoconcha is peculiar. The fresh-water Mollusca, besides the Jsidora characteristic of the sub-region, are partly related to New Caledonia through the occurrence of Melanopsis, partly to Tasmania through Potamopyrgus, while the peculiar Latia is possibly akin to Gundlachia (Tasmania). The land © operculates number only 5 genera and 14 species in all, excluding a doubtful Diplommatina.' Land and Fresh-water Mollusca of the Neozealanian Province Schizoglossa 1 Gerontia. . . 2 Placostylus. 1 Melanopsis . 2 Paryphanta 5 Allodiscus . .10 Carthaea 1 Potamopyrgus 4 Rhytida . 6 Pyrrha . . . 1 Tornatellina 1 Paxillus . k Rhenea . 2 Therasia. . . 7 Janella 3 Lagochilus . 7 Helicarion . 1 Phenacohelix . 3 Latia. 2 Omphalotropis 1 Otoconcha . I Suteria 2-2 2 ip Ameylus:. 2 Realia 4 Microcystis . 1 Flammulina .13 Limnaea. 5 Hydrocena . 1 Trochonanina. 1 Laoma .. .238 Amphipeplea . 2 Unio . 9 Phacussa 3 Endodonta. .10 Planorbis 1 Sphaerium . 1 Thalassohelix . 5 Charopa. . . 28 Isidora 7 Pisidium 2 Lord Howe’s 1. is remarkable as containing a Placostylus, which thus links the island with this province. ‘The remainder of the fauna is Polynesian, with the exception of a species (common to the Fijis) of Parmella, a slug akin to Helicarion, Parmacochlea, and Cystopelta. (3) The Polynesian Sub-region includes all the island groups of the central and southern Pacific (except those classified in the Papuan and Australian sub-regions ), from the Pelews and Carolines in the west to the Marquesas and Paumotus in the east, and from the Tonga group in the south to the Sandwich Is.in the north. It may be subdivided into (a) the Polynesian pro- vince proper, and (6) the Hawaiian pro- Fic. 216. —Characteristie vince, which includes the Sandwich Is. Polynesian Mollusca: A, Achatinella vulpina Feér., only. Sandwich Is.; B, Par- (a) The general features of the Poly- Aca cH pa Bk Pease, nesian province are very similar through- out, although the Mollusca of each island group are in the main peculiar. The species are mostly small 1 Hedley and Suter, Proc. Linn. Soc. N. S. Wales (2), vii. p. 613. Twenty- one species are ‘‘ introduced.”’ * x SANDWICH ISLANDS 327 and obscure. Helix scarcely occurs, its place being taken by small Zonitidae (Microcystis, Charopa, Trochomorpha, etc.), and by groups of so-called Patula (Endodonta, Pitys, etc.), the exact position of which is not yet settled. Libera, remarkable for its method of ovipositing (p. 128), is peculiar to the Society and Hervey Is.; Partula is almost universal, attaining its maximum (40 sp.) in the Society Is.; Zornatellina, Pupa, and Vertigo occur throughout. The land operculates consist chiefly of Omphalotropis, Pupina, Reaha, and Helicina. Diplommatina and Palaina are abundant on the Pelews, and a Moussonia occurs in the Samoa Is. Ostodes, a small form of Cyclophorus, is found in some of the southern groups. The fresh-water operculates are Melania, Neritina Gneluding Clithon, a sub-genus furnished with spines), and Navicella ; there are no Unionidae, while fresh-water Pulmonata are very scarce. (6) The land Mollusca of the Hawaiian province are distin- guished by the possession of four entirely peculiar genera — Achatinella, Leptachatina, Carelia, and Auriculella. More than 300 of the two former genera have been described, every moun- tain valley of some of the islands having its own peculiar species. The destruction of the indigenous herbage by goats is rapidly extinguishing many forms. Partula, and the small land oper- culates, so characteristic of the other groups, are, with the excep- tion of Helicina, entirely wanting. The occurrence of one of the Merope group of Helix (Solomon Is.) is remarkable, and there is a rich development of Succinea. “ Patula,’ Microcystis, Tornatellina, and the other small Polynesian land Pulmonata are well represented. ‘The presence of Jszdora, absent from the central Pacific groups, is remarkable, and Hrinna is a peculiar genus belonging to the Limnaeidae. ait Sacitiggl CHAPTER XI GEOGRAPHICAL DISTRIBUTION OF LAND MOLLUSCA (continued) — THE ETHIOPIAN, NEARCTIC, AND NEOTROPICAL REGIONS D. The Ethiopian Region Tue Ethiopian region includes the whole of Africa south of the Great Desert, and Southern Arabia, together with the outly- ing islands, excepting those of the Atlantidean province (p. 297). Regarded as a whole, the Ethiopian is poorest in land Mollusea of all the tropical regions. And yet its characteristics are very remarkable. The entire Achatina group is peculiar, and takes, especially in W. Africa, some curious forms ( Colwmna, Perideris, Pseudachatina). Carnivorous Mollusca (Hnnea, Gibbus, ete.) are highly developed, especially in the south and east, the largest known helicoid form (Aerope) being from Natal. In the posses- sion of these types of the Agnatha, Africa is more closely related to the Australasian than to the Oriental region. The true Cyelo- stoma are entirely peculiar to the region, but are absent from West Africa. Fresh-water Mollusca are abundant and characteristic, espe- cially in and near the Great Lakes. Lanistes, Cleopatra, and Meladomus, among the operculates, together with Mutela and Aetheria (Unionidae), Galatea and Fischeria (Cyrenidae), are peculiar. In its negative, as well as its positive features, the Ethiopian region is markedly isolated. Helicidae and Naninidae are equally deficient, the former, indeed, attaining some numerical predomi- nance in the extreme south, but the species are nearly all insig- nificant in size and colouring. It is only in Madagascar that Helix asserts itself. Arion, Limax, Hyalinia, Clausilia, and a 328 7 ' & CHAP. XI CENTRAL AFRICAN SUB-REGION 329 number of other genera abundant along the Mediterranean, are either altogether absent, or are very scantily represented. Land operculates, so characteristic of other tropical countries, are almost entirely wanting. If we disregard the Malagasy sub-region, there are scarcely forty species of land operculates on the whole African continent. The Ethiopian region may be divided into three sub-regions: (1) the Central African; (2) the South African; (8) the Malagasy. (1) The Central African Sub-region is bounded on the north by the Great Desert, on the east and west by the ocean, and on the south by a line roughly drawn between the mouth of the Orange River and Delagoa Bay; it also includes 8. Arabia. No natural features exist which tend to break up this vast district into areas of independent zoological development. The absence of long and lofty mountain ranges, the enormous size of the great river basins, and the general uniformity of climate, equalise the conditions of life throughout. It will be convenient to break the sub-region up into provinces, but in most cases no precise line of demarcation can be laid down. (a) The Senegambian Province may be regarded as extending from the mouth of the Senegal River to Cape Palmas. Only 8 genera of land Mollusca are known, including 4 Limicolaria and 3 Thapsia, with 1 small Cyeclophorus. Fresh-water genera are abundant, and include most of the characteristic Ethiopian forms. (6) The West African Province extends from Cape Palmas to the mouth of the Congo, and is rich in Mollusca. The great Achatina, largest of land snails, whose shell sometimes attains a length of 64 in., Limicolaria, Perideris, and Pseudachatina are the characteristic forms. The Agnatha are represented by Ennea, Streptazis, and Streptostele. Rachis and Pachnodus, sub-genera of Buliminus, occur also on the east coast. A special feature is the development of several peculiar slug-like genera, e.g. Oopelta, perhaps a form of Arion; Hstria, a slug with an external shell, akin to Parmacella ; and Aspidelus, a form intermediate between Helicarion and Limazx. Claviger, a handsome group akin to Cerithium, is peculiar to the estuaries of West African rivers. About sixteen species are known from the Cameroons District, but no peculiar genera occur. The French Congo District has - 330 CENTRAL AFRICAN SUB-REGION CHAP. not yet been well explored. Tomostele, a genus allied to Strep- tostele, is peculiar, and Pseudachatina attains its maximum. St. Thomas and Princes Is., in the Gulf of Guinea, are well known. Princes I. has 22 species, 14 peculiar, and 2 common to St. Thomas only, one of the latter being the great sinistral Achatina bicarinata Chem. The remarkable genus Columna (Fig. 217) is peculiar, and Streptostele (4 sp.) attains its maximum. Pecul- iar to St. Thomas are Pyrgina, a turreted form of Stenogyra; Thyrophorella, a sinistral form of Zonites; and ; On, Ory es feelin ist ore ites ns ori oro ooo: : 13 ee) Ra ° Onmo- Bw. Wrw. (oof — Wi — Uae a 34 moos : —s bo orn §. Domingo + mo: CObD: an: 14 SCO Reds sun a 6 14 2 35 1 (2) : co Porto Rico. a No He a oat GO): ae UPA pei SS (ise an mC: Cec: iin = GREATER ANTILLES Opeas Subulima . Glandinella Spiraxis Melaniella . Geostilbia . Cionella Leptinaria. Obeliscus . Pupa. Vertigo Strophia Clausilia Succinea Vaginula Megalomastoma Neocyclotus Licina Jamaicia Crocidopoma Rolleia Choanopoma Ctenopoma Cistula Chondropoma Tudora Adamsiella Blaesospira Xenopoma Cistula Colobostylus Diplopoma Geomelania Chittya Blandiella . Stoastoma . Entrochatella Lucidella . Alcadia Helicina ... | Proserpina. > DOH -1n9 o> oo Cuba. > IR“ Jamaica. CP NEON o een Ww Li alll lg wa ° bd ~I-o Cobo Wb. kr bo 13 21 1 80 6 4 14 1 to: bo §. Domingo. Se eave . KO s . : . . © CNC CH ORM OD. COs mos CO+e COrF. 4 _ Seg mGCO)e us 6 2 = : bo op Porto Rico. s CM Coe hos bohocot ¢ : 351 ar The Virgin Is., with St. Croix, Anguilla, and the St. Bar- tholomew group (all of which are non-volcanic islands), are related to Porto Rico, while Gaudeloupe and all the islands to the south, up to Grenada (all of which are volcanic), show marked traces of S. American influence. St. Kitt’s, Antigua, and Montserrat may be regarded as intermediate between the two groups. St. Thomas, St. John, and Tortola have each one 352 LESSER ANTILLES CHAP. Plagioptycha and one Thelidomus, while St. Croix has two sub- fossil Caracolus which are now living in Porto Rico, together with one Plagioptycha and one Thelidomus (sub-fossil). The gradual disappearance of some of the characteristic greater Antillean forms, and the appearance of S. American forms in the Lesser Antilles, is shown by the following table: — tho OOH: FOO | Guadeloupe. | Porto Rico. OF SS | St. Croix. St. Vincent. Grenada. to | St. Kitt’s. wo | Antigua. Bulimulus Cylindrella . Macroceramus : Cyclostomatidae, etc. . Dentellaria . : Cyclophorus . Amphibulimus Homalonyx . > 6 | Dominica. et Or | Martinique. eo | St. Lucia. > eto | Barbados. Mem | Trinidad, a : S f=) al nD 4 2 1 4 Bebe ee | Tortola. ww > Re: bo | Anguilla. gibOs (d) In Guadeloupe we find Cyclophorus, Amphibulimus, Homalonyzx, and Pellicula, which are characteristic of S. America, and nearly all recur in Dominica and Martinique. These islands are the metropolis of Dentellaria, a group of Helix, evidently related to some of the forms developed in the Greater Antilles. Stragelers occur as far north as St. Kitt’s and Antigua, and there are several on the mainland as far south as Cayenne. ‘Traces of the great Bulimus, so characteristic of South America, occur as far north as 8. Lucia, where also is found a Parthena. (San Domingo and Porto Rico). Trinidad is markedly 8S. American ; 55 species in all are known, of which 22 are peculhar, 28 are common to S. America (8 of these reach no farther north along the islands), and only 5 are common to the Antilles, but not to S. America. The occurrence of Gundlachia in Trinidad has already been mentioned. The Bermudas show no very marked relationship either to the N. American or to the West Indian fauna. In common with the former they possess a Polygyra, with the latter (antro- duced species being excluded) one species each of Hyalosagda, Subulina, Vaginula, and Helicina, so that, on the whole, they may be called West Indian. The only peculiar group is Poecilo-— zonites, a rather large and depressed shell of the Hyalinia type. (2) The Central American Sub-region may be regarded as XI CENTRAL AMERICA 353 extending from the political boundary of Mexico in the north to the isthinus of Panama in the south. It thus impinges on three important districts—the N. American, West Indian, and S. American; and it appears, as we should perhaps expect, that the two latter of these regions have considerably more influence upon its fauna than the former. Of the N. American Helicidae, Polygyra is abundant in Mexico only, and two species of Strobila reach N. Guatemala, while the Californian Arionta.occurs in Mexico. S. American Helicidae, in the sub-genera Solaropsis and Labyrinthus, occur no farther north than Costa Rica. Not a single representative of any of the characteristic West Indian Helicidae occurs. Bulimulus and Otostomus, which form so large a proportion of the Mollusca of Venezuela, Colombia, Ecuador, and Peru, together with Orthalicus, are abundant all over the region. Again, Cylindrella, Macroceramus, and some of the characteristic Antillean operculates, are represented, their occurrence being in most cases limited to the eastern coast-line and eastern slope of the central range. Besides these external elements, the region is rich in indigenous genera. Central America is remarkable for an immense number of large carni- vorous Mollusca possessing shells. There are 49 species of Glandina, the bulk of which occur in eastern and southern Mexico; 86 of Streptostyla (S.E. Mexico and Guatemala, only 1 species reaching Venezuela and another Peru); 5 of Sala- stella, 2 of Petenia, and 1:of Strebelia; the last three genera being peculiar. WStrept- axis, fairly common in 8. America, does not occur. Velifera and Cryptostracon, two remarkable slug-like forms, each with a single species, are peculiar to Costa Rica. Among the especial peculiarities of the ,, fio) 2 saan pieg Net region are the giant forms belonging tothe characteristic Mexican Cylindrellidae, which are known as Holo- _ jollusca: A, ee spira, Hucalodium, and Coelocentrum (Fig. Streptostyla Delattrei 232). They are almost entirely peculiar to Mexico, only 7 out of a total of 83 reaching south of that district, and only 1 not occurring in it at all. VOL, Il ZA abe CENTRAL AMERICA CHAP. The land operculates are butscanty. TZomocyclus and Amphi- cyclotus are peculiar, and Schasicheila, a form of Helicina, occurs elsewhere only in the Bahamas. Ceres (see Fig. 18, C, p. 21) and Proserpinella, two remarkable forms of non-operculate Helicinidae (compare the Chinese Heudeia), are quite peculiar. Pachychilus, one of the characteristic fresh-water genera, belongs to the 8. American (Melaniidae) type, not to the N. American (Pleuro- ceridae). Among the fresh-water Pulmonata, the Aplecta are remarkable for their great size and beauty. In the accompany- ing table “ Mexico” is to be taken as including the region from the United States border up to and including the isthmus of Tehuantepec, and “Central America” as the whole region south of that point. Land Mollusca of Central America Be g oe g Sad Guess or: mo Bee bee Bp eee ee Be S646 soe = 48 2 Strebelia it ae ...| Berendtia . 1 ne Glandina 33 13 3 | Orthalicus 6 3 3 Salasiella 4 a 1 | Pupa 1 AL 1 Streptostyla . 18 12 6| Vertigo ul cee aa Petenia Ma 1 1 | Holospira 12 acct oan Limax ; MN, he ... | Coelocentrum 6 1 1 Velifera 2 eer aiuen 1 ... | Kucalodium . 15 ont 9) Omphalina 10 1 1| Cylindrella . 6 4 eh Hyalinia 2 5) 3 | Macroceramus 2 1 case Guppya é ae 8 3 | Simpulopsis . 2 1 Be: Pseudohyalina 2 2 | Caecilianella 1 She are Tebennophorus . il mas ...|Opeas . iL 2 3 Ciyptostracon. a) ain 1 ... | Spiraxis 8 2 £ Xanthonyx . 4 site Leptinaria oo 2 Re. Patula . 3 Ade 4 | Subulina 2 3 + Acanthinula. 1 2 2 | Succinea 11 3 1 Vallonia ane 1 . | Vaginula Mf — ons Trichodiscus 2 2 3| Aperostoma . =e 4 1 Praticolella . 1 Sid 1 | Amphicyclotus 2 1 2 Arionta ; 3 .. | Cystopoma 2 ee on Lysinoe E : 1 i 1|Tomocyclus . sa 1 2 Oxychona 2 5 Choanopoma 2 2 ne Solaropsis oe eee 2 ... | Chondropoma 2 11 oa Polygyra . sae if 2 | Helicina ‘ 13 10 6 Strobila é if 1 ... | Schasicheila. 2 ite 1 Labyrinthus. aA f 5 ... | Ceres : 2 oes Otostomus . rege 20 7 | Proserpinella 1 “ae Bulimulus . : 6 5 2 (8) The Colombian Sub-region includes Colombia, New Grenada, Venezuela, Guiana, Ecuador, Peru, and Bolivia. It has we XI COLOMBIA AND VENEZUELA 355 been usual to separate off the two latter countries as forming a dis- tinct “ Peruvian” sub-region ; but there is, as will be seen, abso- lutely no line to be drawn between the Mollusca of Peru and those of Ecuador; nor would one, on geographical considerations, expect to be able to draw sucha line. A better method of subdivision, so far as the species of the whole eastern portion of the region are concerned, would be to group the Mollusca according to the altitude at which they occur, were it not that the evidence on this point is at present but fragmentary. We know, however, that all along the line of the Andes certain species, more parti- cularly of Bulimulus, occupy their own zones of elevation, some ascending as high as 10,000 feet above the sea, and never occur- ring on the plains. In the northern portions of this sub-region, Central American and West Indian influence is felt toa certain extent. Thus there Fic. 233. — A, Orthalicus Deburghiae Reeve, Ecuador; B, Bulimus (Pachyotus) egregius Jay, Brazil. are eight Glandina and one Streptostyla in Venezuela and Colom- bia together with one or two species of Cistula, Chondropoma, Proserpina, and Cylindrella, while a single Strophia (decidedly a straggler) occurs at Curagao. In Demerara and Cayenne there are three or four species of Dentellaria. In Ecuador, however, Glandina diminishes to three species, and in Peru disappears altogether, although one Streptostyla occurs. Similarly the West Indian operculates are reduced to one Chondropoma (Ecuador) and disappear entirely in Peru. 356 ECUADOR, PERU, AND BOLIVIA CHAP, The Helicidae are most abundant in the north and west, and are represented by several very striking sub-genera, some of which possess remarkably toothed apertures, and perhaps betray an ancestry common to some of the West Indian genera. Of these, Labyrinthus has 12 species in Venezuela and Colombia, 5 in Ecuador, and 3 in Peru and Bolivia; Zsomeria 12 in Venezuela and Colombia, 20 in Ecuador, and 2 in Peru and Bolivia; ~ Salaropsis is represented in these countries by 6, 3, and 7 species, and Systrophia by 4, 5, and 8 species respectively. Clausilia —in the group MNenza — appears in some numbers along the Andes chain, the only other representative in the New World being the solitary species occurring at Porto Rico. There have been described, from Venezuela and Colombia 10 species, from Ecuador 5, and from Peru and Bolivia 12. Another marked feature of the region is the occurrence of the Orthalicidae, in the two genera Orthalicus and Porphy- robaphe. The latter of these magnificent forms is peculiar, while the former reaches Mexico, the. West Indies, and Brazil. Ecuador, which contains 23 species, seems the metropolis of the group. Bulimus and Bulimulus, the former genus being peculiar to S. America and the adjacent islands, are largely represented, the former in the three groups Borus, Dryptus, and Orphnus. These attain their maximum in Peru, with 25 species, but Venezuela and Colombia have as many as 17. Bulimulus has been subdivided into a number of groups, e.g. Drymaeus, Mesembrinus, Thau- mastus, Mormus, Scutalus, with many others, —the exact scientific limits of which are not easily discernible. It must suffice here to state that Peru seems to be the head-quarters of the group with about 190 species (which probably may well be reduced), Ecuador having about 70, and Venezuela and Colombia between | 80 and 90. Fie. 234. — Rhodea Two very remarkable forms belonging to the ene o> Eieiiae, Anostoma (Fig. 154, p. 248) and Tomi- gerus, occur in Venezuela, the metropolis. Fho- dea, another very peculiar shell (Fig. 284), whose exact family XI THE GALAPAGOS — BRAZIL 357 position is uncertain, is peculiar to New Grenada. The land operculates are few in number, and in Bolivia almost disappear. They belong principally to Neocyclotus (of which 11 species occur in Venezuela and Colombia) and Helzcina (10 species in the same district), besides the stragglers already mentioned from West Indian sources, and a few Cyclophorus. Bourcierta is a form of Helicina peculiar to Ecuador. Ampullaria, with Cera- todes, a peculiar planorbiform sub-genus, and Hemisinus, form the bulk of the fresh-water operculates. The Galapagos. — Thirty-four species of land Mollusca, all peculiar, are known from these islands; 25 of these are forms of Bulimulus. There are no Helicidae, one each of Hyalinia, Leptinaria, and Helicina, and two Pupa. The Bulimulus are mostly of the group Westotis, and in their brown colour bear some outward resemblance to the dark Achatinella of the Sand- wich Is., living as they do mostly under scoriae on the ground, and not on trees. In type, however, they appear to be derived from Chili and Peru, rather than from the parts of S. America immediately contiguous. Another section (Pleuropyrgus 2 sp.) closely resembles a marine Chemnitzia. The islands are all volcanic, and are probably not the result of subsidence; thus the existing species are not to be regarded as the relics of a more widespread fauna, but as a new set of inhabitants. (4) The Brazilian Sub-region.— This immense district is very little known, except in the south, and it is consequently impossible to give any satisfactory account of its Mollusca. It is possible that eventually it will be found that it falls into provinces which correspond more or less to (a) the Amazon basin; (6) the mountainous district in the east, drained by the Tocantins and the San Francisco; (¢) the Parana basin in the south central district; and (d) the Argentine or Pampas district in the extreme south. But at present the data are insufficient to establish any such subdivisions, whose existence, if proved, would have an important bearing on the problem of the coales- cence of S. America into its present form. The Agnatha are represented by Streptazis alone (17 sp.). Helix is rare, but includes the peculiar Polygyratia (Fig. 150 A, p- 246), while Labyrinthus (2 sp.), Solaropsis (5 sp.), and Systro- 1 Compare von Martens, Malak. Blatt. 1868, p. 169; von Ihering, Nachr. Deutsch. Malak. Gesell. 1891, p. 938. 358 ARGENTINA — CHILI CHAP. phia are common with the Colombian Sub-region, and Oxychona (4 sp.) with the Central American. Bulimus has in all 36 species, the sub-genera Pachyo- tus (Fig. 283) and Strophochilus being pecul- iar. Bulimulus, though not so abundant as : in Peru and Ecuador, has about 60 species, of Fic. 235. — Bulimulus which Wavicula (Fig. 235) is the most remark- Cee able group. Megaspira is peculiar. Orthali- cus has only 4 species, while Tomigerus (4 sp.) and Anostoma (3 sp.) are common with Venezuela. Land opercu- lates are scarce, and appear to include only Neocyclotus, Cyclo- phorus, and Helicina. In Argentina, which may probably rank as a ae pro- vince, the tropical forms greatly decrease, Streptaxis being reduced to 2 species, and Bulimus and Bulimulus together to 40, while Orthalicus, the great Helices, and the land operculates disappear altogether. Odonto- stomus (Fig. 236), a genus of the Pupidae, is abundant in the northern part of the province. Two or three species of Chilina occur. (5) The Chilian Sub-region. —The greater Fic. 236. — Odonto- part of Chili, from its arid and rainless climate, stomus pantagru- is unfavourable to the existence of land Mol- oe cae S. lusca. Bulimus (Borus) still has 3 or 4 species, and Bulimulus (Plectostylus 11, Scutalus 9, Peronaeae 1) 3 fairly abundant, but the profusion of the tropics is wanting. There are no carnivorous genera, and only two land operculates. A remarkable form of Helix (Macrocyelis, Fig. 237) is quite peculiar, but the majority of the species belong to two rather obscure groups, Stepsanoda and Amphidoxa. Chilina, a singu- larly solid form of Limnaea (of which 8 sp., with a sub-genus Pseudochilina, occur in Chili), is peculiar to Chili, 8. Brazil, and Patagonia. From the two islands of Juan Fernandez and Masafuera, are known several Helix, of Chilian affinity, several curious Succinea, a Homalonyx, Leptinaria, and Nothus, and three species of Tornatellina, with the almost universal Limazx gagates. The question of the existence at some remote period of a Neantarctic continent, which formed a communication between the three great southern peninsulas of the world, is one on XI QUESTION OF A NEANTARCTIC CONTINENT 359 which the Mollusca may offerevidence. Von Ihering holds that an essential difference can be observed between certain of the Unionidae which inhabit S$. America, Africa, and Australia with New Zealand, and those which inhabit Europe, Asia, and N. America, but the point can hardly be regarded as definitely established at present. Something perhaps may be made of the distribution of Bulimus and Bulimulus. It seems difficult to explain the occurrence of sub-fossil Bulimus on St. Helena except on some such lines as have been recently adduced to account for the presence of struthious birds in the Mascarenes, and possibly the form Livinhacea may be a trace of the same element in S. Africa. Again, the Liparus of 8. and W. Australia, with the Caryodes of Tasmania, and the Leucotaenia and Clavator of Mada- gascar (which all may be related to Bulimus), together with the Placostylus of New Caledonia and the adjacent islands, reaching SX Fic. 237. — Macrocyclis laxata Fér., Chili. - even to New Zealand, and perhaps even the Amphidromus of Malaysia (which are more akin to Bulimulus), may be thought to exhibit, in some remote degree, traces of a common ancestry. The land operculates give no help, and, of the carnivorous genera, Rhytida is a marked link between Africa and Australia, while Streptaxis is equally so between 8S. America and Africa. As regards fresh-water Gasteropoda, Ampullaria is common to 8. America and Africa, while /stdorais common to Africa, Australia, and New Zealand, but is altogether absent from 8. America. Gundlachia occurs in Florida, Trinidad, and Tasmania, but has not been detected in Africa. It must be concluded, therefore, that the present state of the evidence which the Mollusca can afford, while exhibiting certain curious points of relationship between the three regions in question, is insufficient to warrant any decided conclusion. CHAPTER XII DISTRIBUTION OF MARINE MOLLUSCA — DEEP-SEA MOLLUSCA AND THEIR CHARACTERISTICS MARINE Mollusca may be divided roughly into Pelagic and non-Pelagic genera. To the former division belong all Ptero- poda and Heteropoda, and a large number of Cephalopoda, together with a very few specialised forms of Gasteropoda (lanthina, Litiopa, Phyllirrhoe, etc.). Pelagic Mollusca appear, as a rule, to live at varying depths below the surface during the day, and to rise to the top only at night. ‘The majority inhabit warm or tropical seas, though some are exceedingly abundant in the Arctic regions; Clione and Limacina have been noticed as far north as 72°.4 The vertical range of Pelagic Mollusca has received attention from Dr. Murray of the Challenger, Professor Agassiz of the Blake and Albatross, and others. Agassiz appears to have estab- lished the fact that the surface fauna of the sea is limited to a comparatively narrow belt of depth, and that there is no inter- mediate belt of animal life between creatures which live on or near the bottom and the surface fauna. Pelagic forms sink to avoid disturbances of various kinds, to depths not much exceed- ing 150 to 200 fathoms, except in closed seas like the Gulf of California and the Mediterranean, where the bathymetrical range appears to be much greater.? Non-Pelagic Mollusca are, from one point of view, con- veniently classified according to the different zones of depth at 1 The distribution of some Pteropoda has been worked out by Munthe, Bih. Svensk. Ak. Handl. XII. iv. 2, by Pelseneer ‘Challenger’ Rep., Zool. xxiii., and by Boas, Spolia Atlantica. 2 Bull. Mus. C. Z. Harv. xiv. p. 202; xxiii. p. 34 f. 360 CHAP. XII PHENOMENA OF DISTRIBUTION 361 which they occur. Thus we are enabled to distinguish Mollusca of (a) the littoral, (6) the laminarian, (¢) the nullipore, or coralline, and (d) the abyssal zones. It must be borne in mind, however, that these zones cannot be exactly defined, and that while the littoral zone may be understood to imply the area between tide-marks, and the abyssal zone a depth of 500 fathoms and upwards, the limits between the laminarian and the coralline, and between the coralline and abyssal zones can only be fixed approximately. The difficulty of assigning special genera or species to special ‘zones of depth’ is increased by two important facts in the _ phenomena of distribution. In the first place, it is found that species which occur in shallow water in northern seas often extend to very deep water in much lower latitudes. This in- teresting fact, which shows the importance of temperature in determining distribution, was first established by the dredgings of the Lightning and Porcupine off the western coasts of Europe. In the second place, a certain number of species seem equally at home in shallow and in abyssal waters, in cases where a great difference of latitude does not occur to equalise the temperature. Thus the Challenger found Venus mesodesma living on the beach (New Zealand) and at 1000 fath. (Tristan da Cunha); Lima multicostata in ‘shallow water’ (Tonga and Port Jackson) and at 1075 fath. (Bermuda); Scalaria acus from 49 to 1254 fath. (N. Atlantic); and S. hellenica from 40 to 1260 fath. (Canaries). — The Lightning and Porcupine found, or record as found,! Anomia ephippium at 0 to 1450 fath., Pecten groenlandicus at 5 to 1785 fath., Lima subauriculata at 10 to 1785 fath., Modiolaria discors at 0 to 1785 fath., Crenella decussata at 0 to 1750 fath., Dacrydium vitreum at 30 to 2750 fath., Arca glacialis at 25 to 1620 fath., Astarte compressa at 3 to 2000 fath., and Scro- bicularia longicallus at 20 to 2435 fath. Puncturella noachina has been found at 20 to 1095 fath., WMatica groenlandica at 2 to 1290 fath., Rissoa tenuiseulpta at 25 to 1095 fath. In many of these cases we are assured that no appreciable difference can be detected between specimens from the two extremes of depth. In spite, however, of these remarkable vagaries on the part of certain species, we are enabled roughly to distinguish a large 1 See papersin P. Z. S. 1878-85. 362 RECENT EXPLORING EXPEDITIONS CHAP. number of genera as ‘shallow-water’ and ‘ deep-water’ respec- tively, while a still larger number occupy an intermediate position. Among shallow-water genera may be named Patella, Iittorina, Nassa, Purpura, Strombus, Haliotis, Mytilus, Cardium, Solen; while among deep-water genera are Pleurotoma, Scissu- rella, Seguenzia, Dentalium, Cadulus, Limopsis, Nucula, Leda, Lima, and Azinus. Theories on the geographical distribution of marine Mollusca have been revolutionised by the discoveries of recent exploring expeditions. The principal have been those of Torell (Swedish) (1859-61) on the coasts of Greenland and Spitzbergen ; of the Lightning and Porcupine (British) in 1868-70, in the N.E. Atlantic, off the Scotch, Irish, French, and Portuguese coasts, and in the Mediterranean ; of the Challenger (British), under Sir C. Wyville Thomson, in 1873-76, in which all the great ocean basins were dredged or sounded ; of the Blake (American), under Alexander Agassiz, in 1877-80, in the West Atlantic, Gulf of Mexico, and Caribbean Seas; of the Travailleur (French) in 1880-88, off the west coasts of France, Portugal, and Morocco, Madeira, the Canaries, and the Golfe du Lion; of the Talisman (French) in 1882, off the west coast of Africa from Tangier to Senegal, the Atlantic Islands, and the Sargasso Sea; of the Albatross (American) in 1891, off the west coast of tropical America; of several other vessels belonging to the U.S. Fish Commission and Coast Survey, off east American shores; and of the Prince of Monaco in the Htrondelle and Princesse Alice at the present time, in the N. Atlantic and Medi- terranean. The general result of these explorations has been to show that the marine fauna of very deep water is much the same all the world over, and that identical species occur at points as far removed as possible from one another. The ocean floor, in fact, with its uniform similarity of temperature, food, station, and general conditions of life, contains no effectual barrier to the almost indefinite spread of species! To give a few instances. The Challenger dredged Stlenia Sarsii in 1950 fath., 1100 1 A break in this uniformity may be found underneath the course of a great oceanic current like the Gulf Stream, which rains upon the bottom a large amount of food, A. Agassiz (Bull. Mus. C. Z. Harv. xxi. p. 185 f.) explains in this way the richness of the fauna of the Gulf of Mexico as compared with that of the west coast of tropical America. XII WIDE DISTRIBUTION OF DEEP-WATER FORMS 363 miles south-west of Australia, and also in 2650 fath. off the mouth of the Rio de la Plata; Semele profundorum in 1125 fath. near the Canaries, and in 2900 fath. mid N. Pacific; Verticordia deshayesiana in 155 fath. near Cape York, and in 350 fath. off Pernambuco; Arca pteroessa in 2050 fath. mid N. Pacific, in 1000-1675 fath. west of the Azores, and in 390 fath. off the West Indies; Arca corpulenta in 1400 fath. off N.E. Australia, in 2425 fath. mid-Pacific, and in 1875 fath. near Juan Fer- nandez; Lima goliath in T75 fath. off S. Japan, and in 245 fath. off S. Patagonia; Pleurotoma engonia in 700 fath. north- east of New Zealand, and in 345 fath. off Inoshima. A surpris- ing range was occasionally found even in shallow-water species; thus Petricola lapicida was discovered by the same expedition in the West Indies and N. Australia, Cardita calyculata off Teneriffe and in Bass Strait, Arca imbricata off Cape York and in the West Indies, Modiolaria cuneata at Port Jackson and Cape of Good Hope, Lima squamosa at Teneriffe and the Philippines. In these latter cases it is not improbable that the species lives in deep water as well, from which it has not yet been dredged. | It follows from these considerations that any attempt to classify marine Mollusca under Regions and Provinces can only apply to Mollusca which occur at moderate depths. The most important factor in the environment, as determining distribu- tion, is the temperature of the water, which is probably to be regarded as affecting not so much the adult Mollusca as their ova; for the adult might possibly support life under conditions in which the ova would perish. It appears that a sudden change of temperature is the most effective barrier to distribution, and may bring the range of a species to an almost instantaneous stop, while a very gradual change will allow it to extend its range very widely. 1 On the western coasts of Europe and America, where the change in surface temperature is very gradual, Purpura lapillus (the west American ‘species’ are at best only derivatives) is able to creep as far south as lat. 82° (Mogador) in the former case, and lat. 24° (Margarita Bay) in the latter, the mean annual tem- perature of the surface water being 66° off Mogador, with an extreme range of only 8°, and that of Margarita Bay 73°, with an extreme range of only 5°. On the eastern coasts, where the Pacific and Atlantic gulf-streams cause a sudden change of temperature, the Purpura is barred back at points many degrees farther north, viz. at lat. 41° (Hakodadi), surface temperature 52°, extreme range 25°; and at lat. 42° (Newhaven), surface temperature 52°, extreme range 30°. 304 ATLANTIC REGION CHAP. It has been usual to classify marine Mollusca from moderate depths under the following regions and sub-regions : — Regions Sub-regions Regions Sub-regions (1. Arctic. : Australian. 2. Boreal. c Australian | 5 Neozealanian. A. Atlantic and | 3. Celtic. (1. Aleutian. Circumpolar ; 4. Lusitanian. | 2. Californian. | 5. West African. | 3. Panamid¢. | 6. South African. ne Se 4, Peruvian. “fi 1. Indo-Pacific. 15. Magellanic. By Pidoeeae ie: Japanese. | 6. Argentinian. . | 7. Caribbean. 8. Transatlantic. A. The Atlantic Region includes the whole to the eastern shores of the Atlantic, from the extreme north of the Cape of Good Hope, together with the eircumpolar seas, which may be regarded as roughly bounded by the Aleutian Islands and the coast of Newfoundland. (1) The Arctic Sub-region includes the circumpolar seas, and is bounded in the N. Pacific by a line drawn between Cape Avinoff in Alaska, and Cape Lopatka in Kamschatka, so as to exclude the Aleutian Islands. On the western shores of the Atlantic the cold Labrador current brings it as far south as the coast of Newfoundland, but on the eastern shores the influence of the Gulf Stream has the contrary effect, so that the North - Cape may be taken as its southern limit. The principal genera (many species of which are common to the whole sub-region) are Volutomitra, Buccinum, Buccinopsis, Neptunea, Trophon, Bela, Admete, Velutina, Trichotropis, Lacuna, Margarita, Philine, Pecten, Leda, Yoldia, Astarte, and Mya. The shells are generally unicoloured, and of a dead white or rather sombre tint. (2) The Boreal Sub-region may be subdivided into two pro- vinces, the European and the American. The former includes the entire coast-line of Norway, the Faroe Islands, and Iceland (except perhaps the northern coast), and possibly the Shetland Islands; the latter the American coasts from the Gulf of St. Lawrence to Cape Cod (lat. 42°). Thus the Boreal American province does not extend nearly so far south as the Boreal XII BOREAL AND CELTIC SUB-REGIONS 365 European, the reason being that on the American coasts the cold Labrador current, which hugs the land, bars back the advance of southern genera, but allows Boreal genera to spread southwards, while on the European side the warmer conditions produced by the Gulf Stream keep the Boreal species back, and allow more southern forms to spread northwards. Many of the Boreal species occur on both sides of the Atlantic, and thus support the theory of a more continuous fringe of con- tinental land once existing along the north of the Atlantic. Among the prominent genera, besides several of those mentioned under the Arctic Sub-region, are Purpura, Chenopus, Littorina, Gibbula, Natica, Patella, Tectura, Chiton, Doris, Aeolis, Tellina, Thracia. (8) The Celtic Sub-region includes the British Islands (except- ing perhaps the Shetland Islands), the coasts of the North Sea and the Baltic, with N. France to Cape Ushant. The absence of any cold or warm current exerting direct influence upon the coast-line of this sub-region causes a very gfadual change in the conditions of life as we move either southward or northward. The fauna of the British seas contains a decided mixture of northern and southern forms. ‘The following are among the common Boreal species which attain their southward range on our coasts: Tectura testudinalis Mull. (to Dublin Bay and Scarborough), Trichotropis borealis Brod. (to the Dogger Bank), Margarita helicna Fabr. (to Yorkshire and Dublin Bay), I. groenlandica Chem. (western Scotland), Matzca montacute Forb. (to Cornwall), Trophon truncatus Str. (to Tenby), Chiton mar- moreus Fabr. (to Dublin Bay and Scarborough). Buccinum undatum and Lnttorina littorea become very scarce on our extreme south-western coasts. Among Lusitanian species which reach our coasts are Gibbula magus L. (to Orkney and Shetland Islands), Phasianella pullus L. (to Caithness), Galerus chinensis L. (to Milford Haven), Galeomma Turton ‘Turt. (to Weymouth), Car- dium aculeatum L. (to Isle of Man), Solen vagina L. (to north Ireland). It appears from the Mollusca of our Crag formations that at the time of their deposition the temperature of our seas must have been considerably warmer than it is now. ‘Thus in the Crag we find many species and even genera (e.g. Mitra, Fossarus, Triton, Vermetus, Ringicula, Chama) which now occur no farther 3260 - LUSITAINAN SUB-REGION CHAP. north than the southern coasts of the Channel, the west of France, and the Mediterranean. The Baltic, a sea specially liable to violent changes of tem- perature, with a large admixture of fresh water at its eastern end, appears to possess only about 65 species in all. More than 50 genera occurring on the western coasts of Denmark do not enter the Sound. In the eastern portion of the Baltic marine and fresh-water species live together (p. 12). (4) The Lusitanian Sub-region extends from Cape Ushatig in the north to Cape Juby (lat. 28°) in the south, and includes the whole of the Mediterranean, as well as the Azores, Canaries, and Madeira groups. The English Channel acts as an effectual barrier to the northward extension of many species; as many as 81 species which occur in western France do not reach British coasts (P. Fischer). At the same time, the western coasts of France are rather intermediate between the two sub-regions than distinctly Lusitanian, for between 50 and 60 Mediterranean genera do not occur on those coasts. The Mediterranean itself is exceedingly rich in species, about 1200 in all (including deep-water species) being known. A certain number of these belong to tropical genera which here find their northern limit, e.g. Fasciolaria, Cancellaria, Sigaretus, Siliquaria, Chama, Spondylus. Here too occur Carinaria, Lobiger, Oxynoe, Pedicularia, Cypraea, Marginella, Mitra, Dolium, Cassis, Cassidaria, Pisania, Euthria, Vermetus, Argonauta, and many others. A few Celtic and even Boreal species, which occur on the western coasts of Morocco, do not enter the Mediterranean. Among these are Purpura lapillus, Helcion pellucidum, and Tellina balthica. Halia, a rare West African genus akin to Pleurotoma, is found in Cadiz Bay, and the West African Cym- bium occurs on the Spanish coasts as far as Malaga. The Black Sea, whose northern and western coasts are exceedingly cold, is comparatively poor in species. The Sea of Azof is chiefly characterised by forms of Cardiwm. (5) The West African Sub-region extends from Cape Juby to a point probably not very far south of lat. 30° S., the cold cur rent which sweeps up from the Pole probably limiting the south- ward extension of tropical species on this side of Africa, while the warm Mozambique current on the eastern side permits the XII WEST AND SOUTH AFRICAN SUB-REGIONS 367 spread of many Indo-Pacific species almost as far south as the Cape. Owing to its extreme unhealthiness, and the absence of harbours, the sub-region is very little known. The principal genera are Cymbium, Pleurotoma, Marginella, Terebra, Mitra, Agaronia, Murex, Cancellaria, Purpura, Pseud- oliva, Natica, Tellina, Lucina, Tugonia, Schizodesma, and Arca. Studer has enumerated as many as 55 species common to West Africa and the opposite American shores. The north and south equatorial currents, which circulate in this part of the Atlantic, _ probably transport the larvae from one coast to the other. Pur- pura coronata Lam., a characteristic West African species, is represented by a well-marked variety in Demerara. The Mollusca of St. Helena (178 known species) most resemble those of the West Indies, 50 per cent being common, while 30 per cent are common to the Mediterranean. From Ascension Island only 83 species are known, which in their general relations resemble those of St. Helena. (6) The South African Sub-region extends along the coast from about lat. 80° on the west, to about East London on the east. Mr. G. B. Sowerby enumerates 740 species from ‘South Africa,’ but includes in this list Natal species, which more prop- erly belong to the Indo-Pacific fauna. Of these 740, 323 are peculiar, while 67 also occur in European seas, some being familiar on our own shores. It is remarkable to find in a sub- region separated from ourselves by the whole width of the tropics, such well-known forms as Mangilia costata Don., M. septangularis Mont., Cylichna cylindracea Penn., Pholas dactylus L., Solen marginatus Pult., Cultellus pellucidus Penn., Ceratisolen legumen L., Lutraria oblonga Chem., Tellina fabula Gmel., T. tenuis Da C., Modiolaria discors L., and many others. The leading genera are Huthria, Triton, Cominella, Bullia, Nassa, Cypraeovula, Oxystele, Fissurella, Fissurellidaea, Patella, and Chiton. The Mollusca of Kerguelen Island and the Marion and Crozets groups show relationship partly with South America, partly with the Cape, and partly with South Australia and New Zealand, thus showing some trace of a circumpolar antarctic fauna corresponding to, but not nearly so well marked as that of the circumpolar arctic sub-region. Among the remarkable forms 1H. A. Smith, P. Z. 8. 1890, pp. 247, 317. 368 INDO-PACIFIC REGION CHAP. discovered off Kerguelen are Neobuccinum and a sub-genus of Struthiolaria (Perissodonta). B. The Indo-Pacific Region includes the whole of the coast-line of the Indian and western Pacific oceans, from about East London in South Africa to the north of Niphon (lat. 42°) in Japan, with the Red Sea and Persian Gulf, the whole of the Indo-Malay Archipelago, Polynesia to the Sandwich Islands in the north-east, and Easter Island in the south-east, and Australia to Swan River in the west, and to Sandy Cape and Lord Howe’s Island in the east. It is especially the region of coral reefs, which furnish so favourite a home of the Mollusca, and which are entirely absent from the Atlantic Region. (1) The Indo-Pacific Sub-region proper (which includes the whole of this region except that part defined below as the Jap- anese Sub-region) is by far the richest in the world. The marine Mollusca of the Philippines alone (in some respects the nucleus of the whole region) have been estimated at between 5000 and 6000 species, and Jousseaume estimates Red Sea species at about 1000. Some prominent genera are very rich in species. Garrett enumerates from Polynesia 81 species of Conus, 60 of which occur on the Viti Is. .. 21 on the Sandwich Is., and only 14 on the Marquesas, where coral reefs are almost absent; 82 species of Cypraea, Viti Is. 44, Sandwich Is. 31, Marquesas only 13; 167 species of Mitra (besides 29 recorded by others), Viti Is. 120, Sandwich Is. 86, Marquesas 7. Of 50 existing species of Strombus, 39 occur in this region, and 10 out of 11 Hburna. The following important genera are quite peculiar to the region: JVautilus, several forms of Purpuridae, e.g. Rapana, Magilus, Rapa, Melapium, and Ricinula ; Tudicla, several forms of Strombidae, e.g. Rostellaria, Terebellum, Pteroceras, and Rimella ; Cithara, Melo, Neritopsis, Stomatia, Malleus, Vulsella, Cucullaea, Tridacna, Hippopus, Libitina, Glaucomya, Anatina, Aspergillum, and many others. The number of species common to the Red Sea and Mediterranean is exceedingly small, some authorities even deny- ing the existence of a single common species. The present 4 ® XII JAPANESE SUB-REGION — AUSTRALIAN REGION 369 author, from an examination of the shells dredged by Mac- Andrew at Suez, regarded 17 species as common, and Mr. E. A. Smith has confirmed this view with regard to 8 of the species in question.1. The Mollusca occurring in Post-pliocene beds at Suez show that Mediterranean species lived there in comparatively recent geological times. The opening of the Suez Canal appears to have already induced several species to start on their travels from the Medi- terranean to the Red Sea and vice versé. Two Red Sea species (Mactra olorina Phil., Mytilus variabilis Kr.) had in 1882 estab- lished themselves at Port Said, while two Mediterranean species (Pholas dactylus L., Solen vagina L.) had reached Ismailia.” (2) The Japanese Sub-region consists of the Japanese Islands to Niphon, together with Corea and a stretch of adjacent main- land coast of unknown extent. The warm Kuro Siwo current, - sweeping up between Luzon and Formosa, permits tropical species to extend much farther north than on the opposite shores of America, where a cold polar current keeps them back. A certain number of species, however, are common to the two shores of the Pacific, and a few circumpolar species occurring on our own coasts reach Japan, e.g. Trophon clathratus, Puncturella noachina, Mya arenaria, Modiola modiolus, Lasaea rubra, and Nucula tenuis. Among the characteristic generaare Fusus, Siphonalia, Colum- _ barium, Hemifusus, Rapana, Chlorostoma, Pleurotomaria, Hali- otis, and Cyclina. C. The Australian Region includes the Australian coast-line from about Swan R.? (lat. 32° S.) to Sandy Cape (lat. 25° S.), Tasmania, New Zealand, and the adjacent islands (except Lord Howe’s I.). (1) The Australian Sub-region proper (which consists of the 1 A. H. Cook, Ann. May. Nat. Hist. (5) xviii. (1886) p. 380 f; E. A. Smith, EZ. S. 1895p. 291 f. 2C. Keller, Neue denksch. Schw. Gesell. xxviii. 1885, pt. 3. 3 According to Tate (Trans. Roy. Soc. S. Austr. 1887-88, p. 70), ‘ Australian’ species predominate at Freemantle (32°), but Tenison-Woods (J. Roy. Soc. N. S. Wales, xxii. p. 106) holds that the tropical fauna extends as far south as Cape Leeuwin (34°), and that the Australian forms are not predominant until the extreme south. Tenison-Woods regards Cape Byron (31°) as the limit of the tropical fauna on the east coast, while some characteristic tropical genera reach Port Jackson, and a few (e.g. Cypraea annulus) Tasmania. VOL. III ~ 2B 370 AUSTRALIAN REGION CHAP. - whole of the region excepting New Zealand and the adjacent islands) is determined by the influence of the Antarctic Drift, which washes the whole of the southern coasts of Australia, and runs strongly northward between Australia and New Zealand. The E. Australian warm current from the north is. checked at Sandy Cape by this cold current, and flows off to New Zealand, the western shores of which island are consequently much warmer than the eastern. On the western coast of Australia the An- tarctic Drift has less force, and tropical genera accordingly range some 7 degrees farther south on the western than on the eastern coasts. The characteristic genera are Voluta (of which half the known species occur on Australian coasts!), Cominella, Siphonalia, Struthiolaria, Risella, Phasianella, a number of genera belonging to the Trochidae, e.g. Liotia, Claneulus, Huchelus, Thalotia, Hlenchus, Trochocochlea, Zizyphinus, Bankivia; Trigonia, Myo- dora, Myochama, Solenomya, Ephippodonta, Anapa, Mylitta, Meso- desma, and Chamostrea. Trigonia, originally discovered as a recent form in Sydney Harbour (p. 65), is not peculiar to that locality, occurring also off Cape York, West Australia, and Tasmania. (2) The Neozealanian Sub-region includes New Zealand, with the outlying islands (Chatham, Auckland, and Campbell Is.). As many as 455 species (Cephalopoda, 8; Gasteropoda, 311; Scaphopoda, 2; Pelecypoda, 134) have been enumerated by Pro- fessor F. W. Hutton as occurring within the sub-region, of which only 64 are found elsewhere, the proportion of peculiar species being thus nearly 86 per cent. New Zealand therefore is, in its marine, no less than its land Mollusca, greatly isolated. The characteristic genera are Anthora, Cryptoconchus, and Vanganella, which appear to be quite peculiar, Z’rophon, Comi- nella, Huthria, most of the Trochidae also characteristic of S. Australia, Haliotis, Patella; Taria, Mesodesma, Mylitta, Zenatia, Standella, and Myodora. D. The American Region includes the entire coasts of North and South America with the adjacent islands, south of Cape Avinoff on the western, and south 1 A full account of the distribution of Voluta is given by Crosse, Journ. de Conchyl. (3) xix. p. 263, E Xil ALEUTIAN, CALIFORNIAN, PANAMIC SUB-REGION 371 of Cape Cod on the eastern coast, the portions north of these points belonging to the Arctic Sub-region (1) The Aleutian Sub-region consists of the islands of Yesso and Saghalien, with the adjacent shores of the Sea of Okhotsk to Cape Lopatka, the Aleutian Is., and the west American coast from about Cape Avinoff (lat. 60° N.) to St. Jean de Fuca Straits. A certain number of species, probably of arctic origin, are common with British and also with East American shores, the former being the more numerous. Species as familiar to us as Lacuna divaricata Fabr., Trichotropis borealis Brod., Pholas crispata L., Mya truncata L., M. arenaria L., Mytilus edulis L., and Modiolaria nigra Gray, occur. The more characteristic genera are Chrysodomus, Volutharpa, Buccinum, Tectura, Scurria, _ Chiton, Cryptochiton (Cr. Stelleri Midd. is by far the largest known of the Chitonidae, 6 inches long), Tellina and Pecten. (2) The Californian Sub-region extends from St. Jean de Fuca Straits (lat. 48° N.) to Cape St. Lucas, the Gulf of California belonging to the Panamic sub-region. The northern polar current, which washes the shores of this sub-region throughout their whole extent, prolongs the southward range of the more northern genera, and keeps back those more markedly tropical, the latter, however, creeping northward in the warmer waters of the Gulf of California. Some authorities subdivide this immense stretch of coast-line, as characterised by sub-temperate, temperate, and _ sub-tropical genera, into the Oregonian, Californian, and Lower Californian provinces. The characteristic genera are —in the north, Argobuccinum, Lizyphinus, Chlorostoma, Tectura, Scurria, Chiton (Katharina, Mopalia, Tonicia), Cryptochiton, Placunanomia, and M, ytilimeria : _ inthe centre, Purpura, Monoceros, Amphissa, Norrisia, Platyodon, Tapes, and Macoma; and, towards the south, Olivella, Chorus, Macron, Pseudoliva, Trivia, and Haliotis. (3) The Panamic Sub-region extends from the head of the Galf of California to Payta in Peru (lat. 5° 8.). It is exceed- nely rich in species, about 1500 having been described. The _ Mollusca are entirely distinct from those of the Indo-Pacific Region, which, although extending from Natal to the Sandwich Islands, are unable to pass the enormous extent of sea which 372 PANAMIC, PERUVIAN, AND MAGELLANIC SUB-REGIONS cuap. pairs of species, which, while specifically distant, are evidently closely related to one another. Amongst these are, on the Panamic side, Purpura speciosa, Cypraea cervinetta, Cassis ab- breviata, Natica Chemnitzit, and Strombus gracilior, correspond- ing to Purpura deltoidea, Cypraea exanthema, Cassis inflata, Natica maroccana, and Strombus pugilis, on the Caribbean. It is reasonable to conclude that these “analogous species” are de- scendants of a stock which was common to both seas when the isthmus was open (probably not4tater than Miocene times), and which have, since the closing of the isthmus, become modified, some species considerably more than others. Among the characteristic genera (compare p. 8) are Conus, Pleurotoma, Terebra, Murex, Purpura, Oliva, Northia, Cantharus, Columbella, Anachis, Cypraea, Strombus, Cerithium, Coecum, Crepiduia, Crucibulum, Vitrinella; Tellina, Semele, Tellidora ; and Arca. (4) The Peruvian Sub-region extends from Payta in Eee to about the latitude of Conception in S. Chili (87° 8.), being checked from further extension southward by the cold Humboldt current, whose force is distinctly felt as far north as Callao. This cold current thus produces the same results as the similar current which impinges on 8. Africa, but has even more effect in decisively separating the fauna on the two sides of the great peninsula, scarcely a single species being common to the western and eastern _ coasts of S. America. The characteristics of the coast-lines them- selves contribute to this result. The Chilian coast is rocky, and descends abruptly to a great depth, while that of Patagonia and Argentina is sandy and very shallow toa great distance from land. : The characteristic genera are Cancellaria, Columbella, Monoceros, Concholepas, Trochita, Fissurella, Chiton ; Ceronia, Malletia, and Cumingia. Some of the Californian genera, absent or poorly represented in the Panamic Sub-region, reappear in Chili, e.g. Seurria, Tectura, and Chlorostoma. (5) The Magellanic Sub-region includes the coast-line and adjacent islands (with the Falklands) from Conception in S. Chili to about Port Melo in Eastern Patagonia (lat. 45° S.). The principal genera (many of which find a habitat on the gigantic Macrocystis which grows on-every rock at low water) are Euthria, Voluta (6 species, one, V. magellanica, the largest known) xi RGENTINIAN AND CARIBBEAN SUB-REGIONS 373 Monoceros, Photinula, Patella, Chiton ; Modiolarca, Malletia, and Mulinia. Several genera characteristic of the Boreal and Arctic sub-regions recur, e.g. Trophon, Admete, Margarita, Puncturella, Cyamium, and Astarte. (6) The Argentinian! Sub-region extends from about Cape Melo in Patagonia to the neighbourhood of S. Caterina I. in South Brazil (lat. 28° 5.). The sub-region stands in the same relation to the Magellanic, on the east coast, as the Peruvian sub-region on the west, but, owing to the influence of the warm Brazil current, which overpowers the colder water of the Falkland branch of the Cape Horn current, it reaches a point much farther south. , ‘The Mollusca are not well known. The prevailing genera appear to -be Oliva, Olivaneillaria, Voluta, Bullia, Crepidula; Periploma, and Lyonsia. (1) The Caribbean Sub-region.extends from S. Caterina I.in -the south to Florida in the north, and includes the shores of the Gulf of Mexico and the whole of the West Indies. The influence of the warm Brazil current (a branch of the South Equatorial) carries the range of the purely tropical species to a point much farther south than is reached by the tropical species on the west coast. ‘The sub-region is very rich in species, especially on the coral reefs of the Bahamas and N. Cuba, but the exceedingly small tide-fall makes shore collecting somewhat difficult beyond a certain point. The leading generas ate Murex, Purpura, Melongena, Latirus, Marginella, Strombus, Triton, Cerithium, Littorina, Nerita, Scalaria; Tellina, Strigilla, Lucina, and Venus. Pleurotomaria, a genus long regarded as extinct, has been dredged alive off Tobago. As compared“with the tropical fauna of the Old World, that of the New World is poor in peculiar genera (compare p. 368). ° The relations of this sub-region to the West African and the Panamic have been already dealt with (pp. 867 and 872). (8) The Transatlantic Sub-region extends from Florida to Cape Cod (see p. 364). In the north the limits of the sub-region are distinctly marked, in the south Caribbean species intermingle. 1 Usually known as * Patagonian,’ but since the Magellanic Sub-region in- cludes a considerable part of Patagonia, amd since the greater part of sub-region _ (6) lies out of Patagonia, it has been thought advisable to change the name. 374. TRANSATLANTIC SUB-REGION —ABYSSAL MOLLUSCA cuap. Gould and Binney, in their Invertebrata of Massachusetts, enumerate 275 species (Cephalopoda, 6; Gasteropoda, 159; Scaphopoda, 2; Pelecypoda, 108), of which 59 (Gasteropoda, 37; Pelecypoda, 22) are British. Among the characteristic genera are Urosalpinx, EHupleura, Fulgur, Ptychatractus, Nassa, Crepidula; Solenomya, Mactra, Cypricia, Raéta, Astarte, and Yoldia. Our common Littorina littorea appears to have been introduced into Nova Scotian waters in about 1857, no previous trace of it occurring either in literature or shell-heaps. Since then it has spread rapidly into the Gulf of St. Lawrence, and also as far south as Newhaven, and is said to be driving out the indigenous L. palliata from New England shores.1. The debt has been repaid by the introduction into British waters of the American clam (Venus mercenaria L.), which, according to the Manchester City News of 23rd March 1889, was first observed in the Humber in 1864, and has steadily increased up to the present time, when it bids fair to compete, in those waters, with the familiar Cardium edule. Characteristics of Abyssal Mollusca. — Large shells appear to be rare in the great ocean depths, and are usually very fragile ; even moderately-sized specimens are far from common. The only group in which species occur larger than the usual size is the Nudibranchs, which are represented by at least one form larger than an orange. It would seem that abyssal molluscs are much less active and energetic than their brethren on the shores. This view is favoured by the looseness of their tissues, which seem ill adapted for prompt and vigorous action. The tenacious character of the mud on the ocean floor must make rapid motion very difficult. The shell itself is usually fragile and delicate, the upper layers of arragonite being thin as compared with shallow-water species, which makes the nacreous layer, when present, appear unusually conspicuous; in many cases the surface is characterised by a peculiar iridescence or sheen. The colour in the shell of deep-sea Mollusca is never very pronounced, and is often absent altogether. Light pink and salmon, pale yellow and brown, are not uncommon. If the colour is in pattern, it is usually in the form of necklaces of spots, which sometimes coalesce into bands. With regard to sculpture, stout knobs and powerfully buttressed varices, such as 1 Amer. Nat. xx. p. 981. XII . CHARACTERISTICS OF ABYSSAL MOLLUSCA 375 occur in the tropical Murex and Purpura, are not found in deep- sea species. But the ornamentation is frequently elaborate, and the sculpture rich and varied. There is an especial tendency towards strings of bead-like knobs, revolving striae, and delicate transverse waves, the sculpture being in many cases of a character which tends to strengthen the structure of the shell, like the ridges in corrugated iron. A remarkable feature in some deep-sea Mollusca is their singular resemblance, in shape, and particularly in the possession of a strong green periostracum, to some of our common fresh- water species. According to Dr. Dall, the cause of this phe- nomenon is the same in both cases. The fresh-water Mollusca secrete a strong periostracum, in order to protect the shell against the corrosive influence of the carbonic acid gas with which the water is surcharged. The shells of deep-sea Mollusca, living, as they do, in water probably undisturbed by currents of any kind, have to protect themselves against the same eroding influence, and do so in the same way.! Mollusca which live exclusively on algae and other forms of plant life are almost entirely wanting in the great depths, where vegetation is probably unknown. The struggle for existence must be much less keen than in the thickly populated shallows, where vicissitudes of every kind occur. The absence of rapid motion of water must obliterate many of those mechanical effects which tend to produce modifying influences upon the animals affected. In the absence of circumstances tending to cause variation, in the unbroken monotony of their surroundings, species must, one would think, preserve a marked uniformity over an exceedingly wide area of range. Vegetable food being wanting, those genera which in shal- lower waters never taste flesh, are compelled to become carnivo- rous. Characteristic of the great depths are very remarkable forms of Trochidae, in whose stomachs have been found the remains of Corallines and Foraminifera. According to Dr. Dall, the results of this diet show themselves in the greatly increased space occupied by the intestine, in the diminution, as regards size, of the masticatory organs, the teeth and jaws, and also in the pro- longation of the anal end of the intestine into a free tube, which _ carries away the excreta in such a way that they do not foul the 1W.H, Dall, Proc. Biol. Soc. Washington, v. p. 1f. . : 376 CHARACTERISTICS OF ABYSSAL MOLLUSCA __scuar. water taken into the gills. The amount of nutriment contained in the bodies of dead Foraminifera is so small that a compara- tively large quantity must be swallowed to keep the vital energies active, and therefore the amount evacuated must be pro- portionately larger also. The abyssal Trochidae, then, and many other genera, sustain themselves by feeding on the ‘rain’ of dead animal matter which falls upon the ocean floor, not so much hunting their prey as opening their mouths and eating whatever happens to fall into them. Genera which are normally carni- vorous would appear to do the same. The Pleurotomidae, for instance, are a family markedly characteristic of very deep water. Representatives of the genus which occur in shallower water are known to secure their prey while in the living state. But, according to Dr. Dall, a singularly small proportion of deep- sea Mollusca, as compared with those from the littoral region, show signs of having been drilled or attacked by other Mollusca. This could hardly be the case if the Pleurotomidae retained their predatory habits, since they are more numerous in the great depths than any six other families taken together. It has already been mentioned (p. 186) that a large proportion of deep-sea Mollusca are perfectly blind. Amongst other remarkable forms from the great depths may be mentioned Pleurotomaria, with its singular anal slit (Fig. 269, p. 407) extending in some cases half way round the last whorl. Three or four species of this genus, so characteristic of almost all fossiliferous strata down to the Cambrian, have been obtained in very limited numbers off the West Indies and Japan. Dentaliidae, especially the sub-genus Cadulus, find a congenial home in the slimy oceanmud. One ofthe greatest molluscan treasures procured by the Challenger was Gruivillea alabastrina Wats., a magnificent Volute as white as alabaster, 64 inches long, which was dredged from 1600 fath. in the South Atlantic, between Marion Island and the Crozets. Another very curious form, belonging to the same family, is Provocator pulcher Wats., a shell about half the size of Guivillea, of stouter proportions, and with an angulated and patulous mouth. This shell was dredged by the Challenger in comparatively shallow water (105-150 fath.) off Kerguelen Island. Among the Trochidae are the fine new genera Basilissa, Bembiz, and Gaza. The exploring voyages of the American sur- veying steamer Blake, in the Gulf of Mexico and the Caribbean XII REMARKABLE ABYSSAL MOLLUSCA a77 Sea, have given us the remarkable new forms Benthobia (possibly akin to Admete), Mesorhytis (a sub-genus of Fasciolaria hitherto only known from the Cretaceous of North America), and Bentho- dolium (possibly = Oocorys), a genus akin to Cassis. In his report on the Pelecypoda obtained by the Challenger, Mr. E. A. Smith remarks that as a rule “very deep-water ‘benthal’ species certainly have a tendency to be without colour and of thin structure, facts no doubt resulting from the absence of light, the difficulty of secreting lime, the scarcity of food, and other unfavourable conditions of existence.”’ At the same time, he notices that most of the species obtained belong to genera which, even when occurring in shallow water, are thin and colourless, e.g. Neaera, Lima, Cryptodon, Abra, Verticordia, etc. Deep-water species of such genera as have a decided periostracum (Malletia, Limopsis, Leda, Nucula, Arca) retain it with little if any modification. The deep-water Pelecypoda of the Atlantic and Pacific Oceans present no special features of interest. The species are few in number, and the genera are not remarkable either for novelty or peculiarity of form. The greatest depth at which Pelecypoda have been obtained is 2900 fath. mid North Pacific (Callocardia pacifica Sm., Abra profundorum Sm. ); the greatest depth at which Gasteropoda have been obtained is 2650 fath. South Atlantic CStylifer brychius Wats.), both by the Challenger. ‘The deepest Challenger Nudi- branch came from 2425 fath., and the deepest Chiton from 2300 fath. The greatest depth ever dredged is 4575 fath. off the east coast of Japan. CHAPTER XIII CLASS CEPHALOPODA THE Cephalopoda present a complete contrast to the majority of the Mollusca in habits and in many points of organisation. In their power of rapid movement and their means of progres- sion, their extreme ferocity and carnivorous habits, their loss, in so many cases, of a shell, and in its constitution when present, in the general symmetry of their parts, in their reproductive and nervous system, they stand in a position of extreme isolation with nothing to connect them with the rest of the phylum. Professor A. E. Verrill has collected many interesting details with regard to gigantic Cephalopoda occurring on the north- eastern coasts of America. From these it appears that the ten- tacular arms of some species of Architeuthis measure as much as 82, 88, 35, and 42 feet in length, while the total length, including the body, sometimes exceeds 50 feet. Even off the Irish coast a specimen was once captured whose tentacular arms were 80 feet long, the mandibles 4 inches across, and the eyes about 15 inches in diameter! The strength of these giant Cephalopods, aided as they are by formidable rows of suckers and other means of securing a grip, is almost incredible. Cases are not uncommon, in which persons diving or bathing have been attacked, and have with difficulty made their escape. Great damage is frequently inflicted by Cephalopoda upon shoals of fish on British coasts. Off Lybster (Caithness) Lolzgo and Ommastrephes devour the herring, large numbers of which are cut up and bitten on the back of the neck by these creatures. On the American coasts the mackerel fisheries are sometimes entirely spoiled by the immense schools of squid which infest the 1 Trans. Connect. Acad. v. p. 177; Zoologist, 1875, p. 4502. 378 : > CHAP. XIII CEPHALOPODA 379 Bay of St. Lawrence When excited in the pursuit of fish Cephalopoda leap high out of the sea. Dr. W. H. Rush? relates that when about 3800 miles off the coast of Brazil, a swarm of hundreds of decapods flew from the water and landed on the __ deck of the ship, which was 12 feet above the surface level, and they had to go over the hammock nettings to reach it. The common Octopus vulgaris Lam., of British and south European coasts, inhabits some rocky hole, the approaches to which, like the den of a fabled giant, are strewn with the bones of his victims. Homer himself knew how hard it is to drag the polypus out of his hole, and how the stones cling fast to his Fie. 238. — Octopus vulgaris Lam.., Naples: A, At rest; B, in mo- _ tion; f, funnel, the arrow show- ing the direc- tion of the pro- ‘pelling current of water. (After. Merculiano.) suckers. The colour-changes, which flit across the skin of the Octopus, appear, to some extent, expressive of the different emo- tions of the animal. They are also undoubtedly protective, enabling it to assimilate itselfin colour to its environment. Mr. J. Hornell has noticed an Octopus, while crawling over the rock- work in his tank, suddenly change the colour of the whole right _ or left side of its body, and of the four arms on the same side, to a snowy whiteness. They have also been seen to change colour, as if involuntarily, according to the material on which they crawl. 1 Rep. Scotch Fish. iii. 1885, App. F, p. 67. 2 Nautilus, vi. 1892, p. 82. 3 Journ. Mar. Zool. i. pp. 3, 9. 380 CEPHALOPODA — DIBRANCHIATA CHAP. The nerve-centres which control the chromatophores or pigment cells, causing them to expand or contract, are found to connect with the optic ganglia; hence the changes of colour may be regarded as a reflex result of the creature’s visual perception of its surroundings. . Order Dibranchiata. Cephalopoda with two symmetrical branchiae, funnel com- pletely tubular, mouth surrounded by 8 or 10 arms furnished with suckers or hooks, ink-sac and fins usually present, eyes with a lens; shell internal or absent. The Dibranchiata are not known from Palaeozoic strata, and first appear (Belemnites, Belemnoteuthis) in the Trias. Whether they are to be regarded as derived from some form of Tetra- branchiata, e.g. Orthoceras, or as possessing an independent origin from some common stock, cannot at present be decided. They attain their highest development at the present time. The earliest representatives of the Order (the Phragmophora) pos- sessed a shell chambered like that of the Tetrabranchiata. These chambered Dibranchiates rapidly reached their maximum in the upper Lias and as rapidly declined, until at the close of the Cretaceous epoch they were comparatively scarce, only a few genera (Beloptera, Spirulirostra) surviving into Tertiary times. The ordinary Dibranchiate Cephalopod may be regarded as consisting of two parts — (a) the head, in which are situated the organs of sense, and to which are appended the prehensile organs and the principal organs of locomotion; (6) a trunk or visceral ao2, enclosed in a muscular mantle and containing the respiratory, generauve, and digestive organs. The visceral sac is often strengthened, and the viscera protected, by an internal non-spiral shell. The ‘arms’ which surround the mouth are modifications of the molluscan foot (p. 200), and are either eight or ten in number. In the former case (Octopoda) the arms, which are termed ‘sessile,’ are all of similar formation, in the latter (Decapoda), besides the eight sessile arms there are two much longer ‘ tentacular’ arms, which widen at their tips into ‘clubs’ covered with suckers. Remarks have already been made on the generative organs of Cephalopoda (p. 186 f.), the branchiae (p. 170), the nervous xT CEPHALOPODA — DIBRANCHIATA 381 system (p. 206), the eye (p. 182), the radula (p. 236), and the ink-sac (p. 241). One of the most characteristic features of the Dibranchiata are the acetabula, or suckers, with which the arms are furnished. They are usually disposed on the sessile arms in rows (of which there are four in most Sepia, two in Octopus, and one in Hledone),and become more numerous and smaller at the tip of the arm. They are massed together in large numbers of unequal size on the ‘clubs’ in the Decapoda, particularly in Loligo. In most Octopoda their base is flush with the surface of the arm, but in Decapoda the acetabula are ped- unculate, or raised on short stalks. In Octopoda again, the acetabula are fleshy throughout, but in the Decapoda they are strengthened. by a corneous rim with a smooth or denticulate edge (Ommastrephes, Architeuthis). Many of the acetabula on the tentacular and sometimes on. Fic. 239.— ‘Club’ of Loligo vul- the sessile arms of the Onychoteuthidae enclose a powerful hook, which is retractile like the claws of a cat. garis L., show- ing the crowded pedunculate ace- tabula, x 4. In mechanical structure the acetabula consist of a disc with a slightly swollen margin, from which a series of 2 muscular folds converge towards the centre of the disc, where a round aperture leads to a gradually widening cavity. Within this cavity is a sort of button, the caruncle, which can be elevated or depressed like the piston of a syringe; thus wh _.. the sucker 1s applied the piston is withdrawn and a vacuum created (Owen). Fic. 240. — One of the suckers of Architeuthis dux Stp., show- ing the denti- culate margin and corneous ring; p, ped- uncle. In many Octopoda the arms are connected by a web (the umbrella), which sometimes extends up the greater part of the arms (Cirrhoteuthis, some Eledone), at others occurs only at the base. The use of the umbrella is perhaps to assist in loco- motion, by alternate contraction and expansion. A cartilaginous skeleton is well developed, especially in the Decapoda. In Sepia a cephalic cartilage forms a complete ring round the oesophagus, the eyes being situated in lateral prolonga- 3 82 OCTOPODA CHAP. tions of the same. In front of the cephalic cartilage occurs a piece like an inverted T, which supports the base of the anterior arms. The Decapoda have also a ‘nuchal’ cartilage, connecting the head with the anterior dorsal portion of the mantle, while cartilaginous knobs on the ventral mantle button into correspond- ing sockets on the funnel. Sub-order I. — Octopoda.— Body round or bag-like, generally Fic. 241.— Cirrhoteuthis magna Hoyle, S. Atlantic. Two of the left arms and their web have been removed: /, funnel; ji, fi, fins; m, mouth. (After Hoyle, x .) without fins, arms eight, suckers fleshy, usually sessile, oviducts paired, no nidamental glands, shell absent. Fam. 1. Cirrhoteuthidae.— Body with two prominent fins; arms in great part united by a web; one row of small suckers, with cirrhi on each side.— Atlantic and Pacific Oceans, deep water (Fig. 241). ; Fam. 2. Amphitretidae.— Body gelatinous, mantle fused with EXIT OCTOPODA . 383 the funnel in the median line, forming two openings into the branchial cavity; arms with one row of suckers; umbrella extending more than two-thirds up the arms. —South Pacific (Fig. 242). The two pocket-like openings into the branchial cavity are unique among Cephalopoda (Hoyle). Fam. 3. Argonautidae. — Female furnished with a symmetrical, unilocu- lar shell, spiral in one plane, secreted by thin terminal expansions (the vela) of the two dorsal arms, no attachment muscle; suckers in two rows, pedun- culate; male very small, without veligerous arms or shell. — All warm seas (Hig. 243). Pliocene —. The shell consists of three layers, the two external being prismatic, the * os eee middle fibrous. Its secretion by the Is.: e, eyes; f, funnel; p, arms and not by the mantle edge He die te a aad is unique, and shows that it is not homologous with the ordinary molluscan shell. The great controversy on the Argonauta, which once raged with so much fierceness, is now matter of ancient history. It Fie. 243.— Argonauta argo L., the position assumed by a specimen kept in captivity, the arrow show- ing the direction of move- ment: f, funnel; m, mouth, with jaws projecting; sh, shell, with arms as seen through it; wa, webbed arm clasping shell. (After Lacaze-Duthiers.) seems scarcely credible that between fifty and sixty years ago, two of the leading zoologists of the day, Mr. Gray and M. de 3 8 4 OCTOPODA CHAP. Blainville maintained that the animal which inhabits the Argonaut shell is a parasite, without any means of depositing — or forming a shell of its own, but which possesses itself of the Argonaut shell, either by expelling or succeeding the original inhabitant, a supposed nucleo-branchiate (Heteropod) molluse akin to Carinaria. ‘The final blow to this strange hypothesis — which was urged by the most ingenious series of arguments — was given by Professor Owen, who in 1839 brought before the Zoo- logical Society of London the admirable observations of Madame Jeannette Power, who made a continuous study of a number of specimens of Argonauta in her vivarium at Messina. The result of these observations tended to show that the young Argonauta when first excluded from the egg is naked, but that in ten or twelve days the shell begins to form, that the principal agents in the deposition of shell are the two velated or web-like arms; and that portions of the shell, if broken away, are repaired by a deposition of calcareous matter. Fam. 4. Philonexidae.— Mantle supported by two ridges placed on the funnel; large ‘aquiferous’ pores (supposed to introduce water into the tissues) near the head or funnel; suckers in two rows, pedunculate. — Atlantic and Mediterranean. Genera: Ocythoe, arms of unequal size, no intervening mem- brane, third arm on the right hectocotylised (see Fig. 51, p. 138), two aquiferous pores at the base of the siphon; male very small; Tremoctopus, two aquiferous pores between the eyes, two on the ventral side of the head. Fam. 5. Alloposidae.— Mantle edge united to the head by three commissures; arms extensively webbed, acetabula sessile. Hectocotylised arm developed in a cavity in front of the right eye. —N. Atlantic. Fam. 6. Octopodidae.— Head very large, arms elongated, similar, more or less webbed, acetabula usually in two rows, sessile; mantle supported by fleshy bands, no cephalic aquiferous pores. In Octopus proper the web is usually confined to the lower part of the arms; Fischer separates off as Pteroctopus a form in which it reaches almost to their extremity. The third right arm (Fig. 52, p. 140) is hectocotylised, the modified extremity being, according to Hoyle, sometimes minute, sometimes spoon- shaped, with a tendency to transverse ridges, rarely slender and 1 Rep. Brit. Assoc. 1844, Transactions, p. 74; P. Z. 8. 1839, p. 36. SVE XIII DECAPODA 385 very long. The relative length of the pairs of arms varies in different species. Two cartilaginous stylets, imbedded in the dorsal mantle, are said by Owen to represent the shell. Other genera; Pinnoctopus, body furnished with broad lateral wings which meet at the posterior end; Cistopus, a large web prolonged along the sides of the arms, fitted with oval aquiferous pouches, with pores at their base, between each pair of arms; Hledone (Fig. 244), one row of acetabula; Tritaxeopus, Iapetella. Sub-order IT. — Decapoda. — Body oblong, mouth sur- rounded by four pairs of sessile and one pair of tentaculararms, the latter terminated by a ‘club’; acetabula pedunculate and furnished with a corneous Fie. 244. — Eledone Aldrovandi Delle Chiaje, margin; mantle margin locked RADE One Nee ert tc the base of the funnel by a cartilaginous apparatus; head and anterior part of body furnished with aquiferous pores; fins present; mandibles corneous; oviduct single, large nidamental glands in the female; shell internal. The tentacular arms, which are the principal external feature of the Decapoda, are not derived from the same muscular ring as the sessile arms, but arise from the cephalic cartilage, and emerge between the third and fourth arm on each side. In Sepia they can be entirely retracted into a kind of pocket behind the eyes, while in ZLoligo they are simply folded over one another. In _Chiroteuthis the arms are six times as long as the body, and the clubs have four rows of denticulate suckers. The anterior ventral! portion of the mantle is furnished with a singular contrivance for locking it to the funnel, and so render- ing the whole animal more capable of resisting the impact of any force. ‘This contrivance generally consists of a series of ridges or buttons which fit into grooves or button-holes, the ridges being on the interior face of the mantle and the corresponding grooves 1 It is convenient, but not morphologically correct, to apply the terms ‘ ventral’ and ‘dorsal’ in this sense. VOL. III 2C 386 DECAPODA CHAP. on the funnel, or vice versd. The ‘resisting apparatus’ is most elaborate in the pelagic genera, and least so in the more sluggish littoral forms. A similar, but not so complex, arrangement occurs also in the Octopoda. The different forms of the shell appear to indicate successive stages in a regular course of development. We have in Spzrula (Fig. 247) a chambered shell of the Tetrabranchiate type, but of considerably diminished size, which has ceased to contain the animal in its last chamber, and has become almost entirely enveloped in reflected folds of the mantle. These folds gradually concresce to form a definite shell-sac, by the walls of which are secreted additional laminae of calcareous shell- substance. These laminae invest the original shell, which gradually (Spirulirostra, Belosepia) loses the spiral form and becomes straight, even- tually disappearing, while the calcareous laminae alone remain (Sepia). These in their turn dis- appear, leaving only the plate or ‘pen’ upon which they were deposited (Loligo), which itself also, with the shell-sac, finally disappears, surviving only in the early stages of Octopus (Lankester). | The Decapoda are divided, according to the character of the shell, into Phragmophora, Sepio- phora, and Chondrophora.} A. PHRAGMOPHORA.— Arms furnished with , hooks or acetabula; shell consisting of a phrag- Fre. 245. — ‘Club ; of Onychoteu. mocone or chambered sac enclosed in a thin wall this sp., show- (the conotheca), septa pierced by a siphuncle near ing the hooks : : : : and clusters of the ventral margin (in Spzrula alone this cham- fixing cushions hered sac forms the whole of the shell). The and acetabula : : below them, apex of the cone les towards the posterior end of Nee the body, and is usually enveloped in a calcareous guard or rostrum. Beyond the anterior end of the rostrum the conotheca is extended forward dorsally by a pro-ostracum or anterior shell, which may be shelly or horny, and corresponds to the gladius of the Chondrophora. The rostrum consists of calcareous fibres arranged perpendicularly to the planes of the laminae of growth, and radiating from an axis, the so-called 1 ppayuds, partition ; ohrioy, cuttle-bone ; xédvdpos, long cartilage. XIII | DECAPODA 387 apical line, which extends from the extremity of the phragmocone to that of the rostrum. Dz¢stribution, see p. 380. Fam. 1. Spirulidae.— Arms with acetabula, shell a loose spiral, without rostrum or pro-ostracum, partially external, enclosed in two lobes of the mantle (Figs. 247 and 248). The single species of the single genus CS. Peronit Lam. =laevis Gray) has not yet been thoroughly investigated, although the shell occurs in thousands on many tropical beaches, and is some- times drifted on our own shores. The animal appears to have the power of adhesion to the rocks by means of a terminal sucker or pore. The protoconch is present, and contains a prosiphon, which does not connect with the siphuncle. The _ septal necks are continuous, not broken as in Nautilus. The siphuncle is on the ventral margin of the shell, the last whorl of which projects slightly on the dorsal and ventral sides, but is even there covered by a thin fold of the mantle. The retractor muscles of the funnel and of the head find their point dappui on the shell, the last chamber of which contains the pos- terior part of the liver, with which the membranous siphuncle is connected. Fam. 2. Belemnitidae. — Arms hooked as in Onychoteuthis, fins large; phragmocone straight, initial chamber globular, larger than the second, ros- trum often very long, investing the phragmocone, pro-ostracum sword- or Fre. 246.— Sepia officinalis L., leaf-shaped, rounded in front, seldom Deere. AP show position of internal preserved, ink-sac present. — Lower shell. x4. (The ends of the Mie to Cretaceous. tentacular arms are cut off.) The Belemnitidae are believed to have been gregarious, and to have lived in shallow water on a muddy bottom. Specimens are sometimes found in which even the ink-sac can be recognised in situ. The relative proportions of rostrum and phragmocone vary greatly in different groups, the rostrum being in some cases two feet long, in others only just enclosing the phragmocone, 388 DECAPODA ' ipticum different angles from the head, is the most M‘Coy, Silurian: B, striking feature in the living Nautilus, and —Perture ee act ; S,S, Septa; Sz, accounts for its being described, when seen position of siphuncle. on the surface, as ‘a shell withsomething like ‘After Blake.) a cauliflower sticking out of it.’ The funnel is nota complete tube, but is formed by the overlapping of the margins of two thin fleshy lobes (which are probably morphologically epipodia), so that when the two lobes are parted, a broad canal appears, leading to the bran- chial cavity. The head isconical,and the mouth and its appendages can be retracted into a sort of sheath, over which fits the ‘ hood.’ Other genera are Trocholites, Gyroceras, Hercoceras, Discites, Aturia. — Ordovician to present time. Fam. 11. Bactritidae. — Shell straight, conical, siphuncle small, marginal, septal necks long, funnel-shaped, sutures undu- lating, with a sinus corresponding tothe siphuncle. This family, from the form of its sutures, appears to constitute a passage to the Ammonoidea. Single genus, Bactrites. — Silurian and Devonian. (6) Prosiphonata. — Septal necks directed forwards. The two genera are Bathmoceras (Ordovician), shell straight, 1 Saville Kent, Proc. Roy. Soc. Queensland, vi. p. 229. 306 ; AMMONOIDEA CHAP. conical always truncated, siphon marginal; and Wothoceras (Silurian), shell nautiloid with simple sutures. Sub-order 2. Ammonoidea.— Shell multiform, straight, curved, flat spiral, or turreted, sutural line more or less complex, siphuncle simple. Some authorities hold that the members of this great sub- order, now totally extinct, belong to the Dibranchiata, on the ground that the protoconch resembles that of Spirula rather than that of the Nautiloidea. Others again regard the Am- monoidea as a third, and distinct Order of Cephalopoda. Their distribution extends from the Silurian to (possibly) the early Tertiary. No trace has ever been found of an ink-sac, mandible, or hooks on the arms; the shell was undoubtedly external. The sutural line, which indicates the septa, and is generally concealed beneath the outer layer of shell, consists of a number of lobes or depressions, the concave part of which is directed towards the aperture. Between these lobes lie corresponding elevations, or saddles, the convex part of which is directed S@° (Sa 5ST s.L SV S.S Fic. 256.— Diagram of the sutures of Ammonites: A, an elaborate suture (Phylloceras); B, a simple suture (Ceratites) ; s.s, siphonal, s.v, ven- tral, s.l, first lateral, s.l’, second lateral saddles; s.a, s.a, auxiliary saddles; /.v, ventral, /, first lateral, l', second lateral lobe; /.a, l.a, aux- iliary lobes. The arrow points to- wards the aperture. (From Wood- B ward.) Compare Fig. 258. 1 i 1 i i] i) i) A Late, L L.v towards the aperture. There are six principal lobes (Fig. 256) the siphonal or ventral, which is traversed by the siphuncle, the dorsal, and a superior and inferior lateral on each side; smaller auxiliary lobes may succeed these latter. The adjacent saddles have received corresponding names. Asa rule the sutural line is very complex, but in some cases (oniatites, Lobites) it is simple (Fig. 258, A). The first saddle of a large number of genera serves as a means of classification, according as it is broad or narrow. Some authorities reverse the terms ventral and dorsal, as applied above. It is probable, however, that the position of XIII AMMONOIDEA 307 the animal of Ammonites in its shell resembled that of Nautilus. The siphuncle is dorsal (internal) in Clymenia only, ventral (external) in all other genera. The aptychus of Ammonoidea is a corneous or calcareous valve-like body, generally formed of two symmetrical parts (Fig.257). It has been regarded by some as the covering of the nida- SW mental gland, and hence as occurring Fie. 257.—Aptychus of Ammonite only in the female, by others, with more ee ee ees He ied probability, as an operculum, covering or imbedded in a hood formed, as in Nautilus, of modified arms. Sometimes the Aptychus is in a single piece (Anaptychus), some- times the two pieces are united on the median line (Synaptychus). The Ammonoidea are thus classified by Dr. P. Fischer : — (a) Retrosiphonata Goniatitidae. ( First saddle, { Arcestidae, Tropitidae, No Aptychus or wide Ceratitidae, Clydonitidae. Anaptychus , Pinacoceratidae, Amal- (6) Prosiphonata corneous, First eal theidae, Ammonitidae, single {| narrow Lytoceratidae. double or united ceratidae. (a) Retrosiphonata. Fam. 1. Goniatetedae.—Shell nautiloid, whorls sometimes disjoined, siphuncle ventral or dorsal, sutures simple. Principal genera: Clymenia, Groniatites (Fig. 258, A). — Devonian to Carboniferous. (6) Prosiphonata. Fam. 2. Arcestedae. — Shell globular, smooth or striated and rayed, body-chamber very long, aperture often with a projecting hood, umbilicus closed by a callosity, lobes numerous, foliaceous, aptychus present. Principal gen- era: Arcestes, Lobites.— Principally Trias. Fam. 8. Tropitidae.— Differs from Arcestidae mainly in the more highly ornamented surface, which is decorated with ribs which become granular at the periphery. Principal genus, Tropites. — Trias and Lias. Fam. 4. Ceratitidae.— Shell ribbed and tuberculated, body- chamber short, lobes denticulated, saddles simple. Principal genera: Ceratites (Fig. 258, B), Trachyceras.— Principally Trias. Fam. 5. Clydonitidae.—Shell variable in form, body-chamber ae calcareous, valves f Harpoceratidae, Stephano- L 398 AMMONOIDEA CHAP. short, sutural line undulated, simple. Principal genera: Cly- donites, Choristoceras, Rhabdoceras, Cochloceras.— Trias. Fam. 6. Pinacoceratidae.— Shell discoidal, usually smooth, body-chamber short, sutural line very complex, lobes numerous. Principal genera: Pinacoceras, Sageceras. — Carboniferous to Trias. Fam. T. Amaltheidae.—Shell broad, keeled, last whorl con- cealing most of the spire, sutures with auxiliary lobes, incised. —Principal genera: Amaltheus, Schloenbacia, Sphenodiscus.— Trias, Cretaceous. . Fam. 8. Ammonitidae.— Body-chamber long, whorls narrow, Fic. 258. — Various forms of Ammonoidea: A, Goniatites crenistria J. Phil., Carb. Limestone; B, Ceratites nodosus de Hann., Muschelkalk ; C, Ammonites (Parkin- sonia) Parkinsoni Sowb., Inf. Oolite; D, Phylloceras helerophyllum Sowb., Upper Lias; s, s, sutural lines. uncovered, more or less ribbed, aperture simple, sutural line normal, aptychus single,corneous. Principal genera: Ammonites, Aegoceras.— Principally Lias. Fam. 9. Lytoceratidae.—Shell discoidal, body-chamber short, aperture simple, no aptychus. Principal genera: Lytoceras, Phylloceras (Fig. 258, D).— Trias to Cretaceous. Fam. 10. Harpoceratidae.—Shell discoidal, compressed, margin keeled, surface with straight or arched ribs, aperture XIII AMMONOIDEA 399 with lateral projections, suture with accessory lobes, aptychus in two pieces. Principal genera: Harpoceras, Oppelia, Lissoceras. — Jurassic to Cretaceous. Fam. 11. Stephanoceratidae.— Shell discoidal, helicoid or straight, whorls sometimes disunited, surface often with bifur- cating ribs, which are tubercled, : ae es aperture often with lateral pro- \\ Wy iy,’ jections, sutural line isa WN Xi UD? aptychus in two pieces, some- =? : times united. In the discoidal group, Ste- phanoceras is strongly ribbed, tubercled at the point of bifur- cation, Cosmoceras has long lateral projections of the aper- ture when young, Perisphinctes has a large body-chamber and numerous smooth ribs. Other genera are Acanthoceras, Pelto- ag Bes Asp idoceras, and Hop lites. Fic. 259.— A, Turrilites catenulatus d’Orb, Among the loosely whorled Gault; B, Macroscaphites Iranii d’Orb, genera, Scaphites (Fig. 260, A) Upper Neocomian. (From Zittel.) has the last whorl produced and bent back again in horse-shoe form, while the early whorls are concealed ; Hamites, Hamulina, and Ptychoceras have a shell shaped like a single or double hook, the sides of which may or may not be united ; Crioceras (Fig. 260, B) in form of whorls resembles % a WSpirula, Ancylo- E> cerasa Scaphites with raat fs the first whorls dis- 1) 4S united. Macrosca- HUTT phites (Fig. 259, B) is similar, but with Fic. 260.—A, Scaphites aequalis Sowb., Cretaceous; B, the first whorls Crioceras bifurcatum Quenst., Cretaceous. (From Zittel.) wicca and ee cane cealed. Turrilites (Fig. 259, A) is turreted and sinistral, while Baculites is quite straight, with a long body-chamber. CHAPTER XIV CLASS GASTEROPODA — AMPHINEURA AND PROSOBRANCHIATA Order I. Amphineura BILATERALLY symmetrical Mollusca, anus at the terminal end of the body, dorsal tegument more or less furnished with spicules. Sub-order 1. Polyplacophora (Chitons ).— Foot co-extensive with ventral surface of the body, dorsum with eight transverse plates, articulated (except in Chitonellus), a row of ctenidia on each side between the mantle and the foot. Silurian The Chitons are found in all parts of the world, ranging in size from a length of about half an inch to six inches or more in the giant Cryptochiton. Although in the main sub-littoral, they occur at very great depths; the Challenger dredged Leptochiton benthus Hadd. at 2300 fathoms. Chiton Poli exceptionally occurs at Malta—teste MacAndrew —above sea margin, but within reach of the ripple. As a rule, the Chitons live in con- cealment, on the under surface of stones or in deep and narrow fissures in the rocks. When the stone to which they are attached is turned over, they crawl slowly to the side which is not exposed, as if disliking the hght. An undescribed species, however, which I took at Panama, crawled quite as fast as an ordinary snail. Chiton fulvus Wood, apparently is accustomed to crawl with some rapidity. MacAndrew took it in abundance on his anchor chain in Vigo Bay every time his yacht was got under weigh. He also found it crawling in sand on the shore, to which habit is no doubt due its extreme cleanness and freedom from the foreign growths which are so characteristic of many of the species. When detached a Chiton contracts the muscles of the whole body, and rolls up into a ball like a wood-louse. 400 ae eg CHAP. XIV POLY PLACOPHORA 40! The Polyplacophora are characterised, externally, by their usually articulated shell of eight plates or valves, which is surrounded and partly kept in position by a muscular girdle. These plates over- lap like tiles on a roof in such a way that the posterior edge of the first, cephalic, or anterior valve projects over the an- terior edge of the succeeding valve, which in its turn overlaps the next, and so on Fie. 262.— Valves of Chitonellus separated out (anterior valve uppermost): a, a, ar- ticulamentum; ¢, ¢, tegmentum. x2. throughout. Seven- valved monstrosities very rarely occur. A certain portion of each valve is cov- ered either by the girdle or by the valve next anterior to it. This portion, which is whitish in colour and non-porous in struct- ure, forms part of an Fy¢.261.—Valves of a Chiton inner layer which separated to show the : various parts (anterior underlies the rest of yalve uppermost): a, a, the substance of the articulamentum; d, beak; : Jj, jugum ; pl, pl, pleura; valve, and 1s called t, ¢, tegmentum. the articulamentum. The external portion of the valves, or teg- mentum, is generally more or less sculptured, and is largely composed of chitin, impregnated with salts of hme, thus answering more to a cuticle than to a shell proper. It is very porous, being pierced by a quantity of minute holes of two sizes, known as megalopores and micropores, which are connected together by minute canals containing what is probably fibrous or nerve tissue, the mouths of the pores being occupied by sense organs connected with these nerves. The tegmentum of the six intermediate valves is generally divided into three triangular areas by two more or less prominent ribs, VOL. III 2D 402 POLYPLACOPHORA CHAP. which diverge from the neighbourhood of the median beak or umbo. The space enclosed between these ribs is known as the median area or jugum, the other two spaces as the lateral areas or pleura. The ribs terminate with the edge of the tegmentum, and ~ are not found on the articula- mentum. In certain genera these areas are either non-existent, or are not distinctly marked. The sculpture of the lateral areas (which is, as a rule, much stronger than that of the median area) will generally be found to resemble that of the anterior valve, which has no proper median area. In duis the posterior valve the median Fie. 263.—First, fourth, and eighth area is very small, while the an eas Chiton, showing 2, seulpture of the rest of the valve aminae of insertion; n, n, notches; s.l, s.l, sutural laminae. x 2. corresponds to that of the lateral areas generally (see Fig. 261). The articulamentum of the intermediate valves is divided into two equal parts in the middle of the anterior edge, opposite to the beak, by a senws. Each of the portions thus formed is again divided by a notch or suture into two unequal parts, the anterior of which is known as the sutural lamina, and is more or less concealed by the valve in front of it, while the lateral part, or lamina of insertion, is entirely concealed by the girdle. The articulamenta of the anterior and posterior valves are either simple or pierced by a series of notches (Fig. 263). The girdle of the Chitonidae varies considerably in character. Sometimes its upper surface is simply corneous or cartilaginoid, with no other sculpture than fine striae, at others it is densely beset with spines or bristles, or tufted at intervals with bunches of deciduous hairs; again it is marbled like shagreen or mossy down, or covered with serpent-like scales. The width of the girdle varies greatly, being sometimes very narrow, sometimes entirely covering all the valves (Cryptochiton). As a rule, its outer edge is continuous, but in Schizochiton it is sharply notched over the anus. XIV POLYPLACOPHORA 403 A description has already been given of the dorsal eyes in Chiton (p. 187), the nervous system (p. 202), the branchiae (p. 154), the radula (p. 228), and the generative system (p. 126). The recent Chitons are thus classified by Dr. W. H. Dall : — SECTION I. CHITONES REGULARES.— Anterior and posterior valves of similar character. A. Leptoidea. — Insertion plates obsolete, or, if present, unslit; Leptochiton, Hanleyia, Hemiarthrum, Microplaz. B. Ischnoidea.— Insertion plates sharp, smooth, fissured ; with eaves ; Trachydermon, Callochiton, Tonicella, Schizo- plax, Leptoplax, Chaetopleura, Spongiochiton, Ischnochi- ton, Callistochiton. C. Lophyroidea.— Insertion plates broad, pectinated, project- Fig. 264.—Girdles of various Chitonidae. A, Radsia sulcata Wood, 9 x 22 8B, Maugeria granu- lata Gmel 3x73) 5 C,Enoplochiton niger Barnes, x 3; D, Acanthochiton jyascicularis Mi, x 4; E, Tonicia fas- tigiata Sowb., x 4. ing backward; Chiton, Tonicia, Hudoxochiton, Craspedo- chiton. j D. Acanthoidea. — Insertion plates thrown forward; Sclero- chiton, Acanthopleura, Dinoplax, Middendorffia, Nuttal- lina, Arthuria, Phacellopleura. SECTION IJ. CHITONES IRREGULARES. — Posterior. valve abnormal, or with a sinus behind. EK. Schizoidea.— Posterior valve fissured; Lorica, Schizochiton. F. Placiphoroidea.— Posterior valve unslit, internally ridged, umbo nearly terminal; Hnoplochiton, Ornithochiton, Plaxiphora. G. Mopaloidea. — Posterior valve with posterior sinus and one slit on each side; Mopalia, Katherina, Acanthochi- ton, Notoplaz. 404 APLACOPHORA CHAP. H. Cryptoidea.— With double sutural laminae; Crypto- conchus, Amicula, Cryptochiton. 4 anv .— Fic. 265.— Chitonellus fasciatus Quoy ; ant, anterior end. I. Chitonelloidea. — Posterior valve funnel shaped; laminae thrown forward; Chitonellus, Choneplaz. f Sub-order 2. Aplacophora. — Animal vermiform, foot absent, or a mere groove, cuticle more or less covered with spicules. Fie. 266. — Neomenia : ’ } carinata Tullb.: a, worm-like exterior being anus; gr, ventral que to adaptation to sur- groove; m, mouth. fj roundings. They have hitherto been found chiefly in the N. Atlantic and Mediterranean, generally at considerable depths, and often associated with certain polyps in a way which suggests a kind of commensalism. | Fam. 1. Meomeniidae.— Foot a narrow eroove, intestinal tube without differentiated liver, kidneys with common exterior orifice, sexes united, ctenidia present or absent. Genera: Meomenia (Fig. 266), Paramenia, Proneomenia, Ismenia, Lepidomenia, Don- dersia. According to Marion, one of the principal authorities on the group, the Aplacophora are perhaps Amphineura whose development has been arrested at an early stage, their SSS SS Fia. 267.—Chaetoderma nitidulum Lov.: 4a, anus; m, mouth. x 3. Fam. 2. Chaetodermatidae.— Body cylindrical, no ventral groove, liver a single sac, kidneys with separate orifices into the branchial cloaca, two bipectinate ctenidia. Chaetoderma (Fig. 267). Single genus, Order II. Prosobranchiata Visceral loop twisted into a figure of 8 (streptoneurous ), right XIV DIOTOCARDIA — RHIPIDOGLOSSA 405 half supra-intestinal, left half infra-intestinal; heart usually in front of the branchia (ctenidium), which is generally single; head with a single pair of tentacles; animal dioecious, usually marine, more or less contained within a shell, operculum generally present. Cambrian to present time. . Sub-order 1. Diotocardia. — Heart with two auricles (except in the Docoglossa and Helicinidae), branchiae bipectinate, front end free; two kidneys, the genital gland opening into the right (except in Neritidae); nervous system not cencentrated; no proboscis or siphon, penis usually absent. (a) DococLossa (p. 227).— Heart with a single auricle, ventricle not traversed by the rectum, visceral sac not spiral, shell widely conical, non-spiral, no operculum; radula very long, with few hooked teeth in each row. Fam. 1. Acmaeidae.— Left ctenidium alone occurring, free on a long stalk. Cretaceous Principal genera: Pectino- donta, front part of head much produced, radula 0 (1. 0.1.) 0; Acmaea (= Tectura), with sub-genera Collisella and Collisellina, no accessory branchial ring, shell closely resembling that of Patella, but generally with a distinct internal border; Seurria, _ accessory branchial ring on the mantle. Fam. 2. Lepetidae.—No ctenidia or. accessory branchiae, animal generally blind. Pliocene Principal genera: Lepeta; Propilidium, apex with internal septum; Lepetella. Fam. 38. Patellidae.— No ctenidia, the osphradial patch at the base of each alone surviving, a circlet of secondary branchiae between the mantle and sides of the foot. Ordovician G.) Patellinae. —Three lateral teeth on each side, two of them anterior. Principal genera: Patella, branchial circlet complete; chief sections Patella proper, Scutellastra, Ancistromesus (A. mexicana Brod., measures 8-14 in. long); Helcion, branchial circlet interrupted in front; Tryblidiwm (Ordovician). — (ii.) Nacellinae. —'Two developed laterals on each side, one anterior. Genera: Nacella, branchial circlet complete; Helcioniscus, bran- chial circlet interrupted in front. (6) RuatPmoGeLossa (p. 225). — Ventricle of the heart tray- ersed by the rectum (except in Helicinidae), one of two ctenidia; jaw in two pieces, radula long, marginals multiplied, rows curved. Of all the Gasteropoda, this section of the Diotocardia approach nearest to the Pelecypoda, particularly in the least 406 DIOTOCARDIA — RHIPIDOGLOSSA CHAP. specialised forms. The auricle, the branchiae, and the kidneys are in many cases paired, and more or less symmetrical. The ventricle is generally traversed by the rectum, there is a long labial commissure between the cerebral ganglia, special copula- tive organs are usually absent, while the shell is often nacreous, like those of Pelecypoda of a primitive type. SECTION I. ZYGOBRANCHIATA. — Two ctenidia, shell with apical or marginal slit or holes, corresponding to an anal tube in the mantle (p. 265). Fam. 1. Mssurellidae.— Two symmetrical ctenidia and kid- neys, visceral mass conical, shell conical, elevated or depressed, with a single anterior or apical st or impression; no operculum. Jurassic Ci.) Fissurellinae. Shell wholly external, apex entirely removed by perforation, apical callus not truncated posteriorly; cen- tral tooth narrow. Genera: Fissurella (Figs. 171, p. 261; 178, p22) yam suridea, Clypidella. (ii.) Kissurelli- dinae. Shell partly internal, otherwise as in (i.); central tooth broad, mantle more or less reflected over the shell, apical hole very wide. Genera: s- — surellidaea, Pupillaea, Lucapina,Mega- tebennus, Macroschisma, Lucapinella. Cu.) Hmarginulinae. Shell usually Fic. 268. — Scutus australis Lam., wholly external, apex usually not re- Australia: m, m, mantle; sh, 4 ‘ 2 shell. x 3. moved by perforation, sometimes with internal septum, anal tube in a narrow slit or sinus. Genera: Glyphis, externals of Fissurella, but hole- callus truncated behind; Pwcturella (sub-genera Cranopsis and Fissurisepta), slit just anterior to the apex, a small internal septum ; Zezdora, large internal septum as in Crepidula: Hmar- ginula, shell elevated, sht very narrow, on the anterior margin Cin subg. Rimula, it is between the apex and the margin), radula bilaterally asymmetrical; Subemarginula, margin indented by a shallow groove; Scutus (= Parmophorus) shell oblong, depressed, nicked in front, largely covered by the mantle. Fam. 2. Haliotidae.— Right ctenidium the smaller, epipodial line broad, profusely lobed; shell rather flattened, spire short, last whorl very large, with a row of perforations on the left side, XIV DIOTOCARDIA — RHIPIDOGLOSSA 407 which become successively obliterated; through these holes, the posterior of which is anal, pass tentacular appendages of the mantle; nooperculum. Cretaceous . Single genus, Halvotis ; principal sub-genera Padollus, Teinotis. Fam. 8. Pleurotomartidae.— Central tooth single, narrow, about 26 laterals, 60 to 70 uncini. Shell generally variously trochiform, nacreous, operculate, with a rather broad marginal sinus in the last whorl; as this sinus closes up it forms an “anal fasciole”’ or “sinus band.” Cambrian Principal genera: Scissurella, epipodial line with several long ciliated appendages at each side, shell very small, slit open, sinus band extending nearly to apex; Schismope, anal slit closed in the adult into an oblong perforation; Murchisonia (Palaeozoic only), shell long, turreted, whorls angulate or keeled with a sinus band; Odontomaria (Palaeozoic only), shell tubular, curved; Polytre- maria (Carboniferous), shell turbinate, slit a series of small holes connected by a passage; Zrochotoma, shell trochiform, perfora- tion consisting of two nar- row holes united by a sht; Pleurotomaria, branchiae almost symmetrical, radula as above, shell variously spiral. In Pleurctomaria we have the case of a genus : Fic. 269. — Pleurotomaria adansoniana Cr. and long supposed to be extinct. F., Tobago. x 4. More than 1100 fossil species have been described, and within the last 88 years about 20 specimens, belonging to 5 species, have been discovered in a living state. Fam. 4. Bellerophontidae.— Shell nautiloid, spire generally concealed, aperture large, sinus or perforations central (Fig. 179, p-. 266). Ordovician— Trias. Genera: Bellerophon, Trema- tonotus, Cyrtolites. SECTION II. AZYGOBRANCHIATA.— One ctenidium, (the left) present. 408 DIOTOCARDIA — RHIPIDOGLOSSA CHAP. Fam. 1. Coceulinidae.— A single cervical ctenidium, foot broad, no eyes, shell patelliform, with caducous spire. Single genus, Cocculina. Deep water. Fam. 2. Stomatellidae.— A single (left) ctenidium, front third free, shell nacreous, spiral or patelliform, depressed, last whorl large. Jurassic . Genera: Stomatella (subg. Synaptocochlea, Niphonia), shell depressed, spirally ribbed, spire short, operculum present; Phaneta, fluviatile only, shell trochiform, imperforate, last whorl keeled, sinuate in front; Stomatia, spire short, surface tubercled or keeled, no operculum: Gena, shell haliotis-shaped, surface smooth, aperture very large: Broderipia, shell patelli- form, spiral apex often lost. Fam. 38. Cyclostrematidae. — Tentacles ciliated, thread-like, snout bilobed, foot truncated in front, angles produced into a filament, shell depressed, umbilicated, not nacreous. Eocene Principal genera: Cyclostrema, Teinostoma, Vitrinella.. Fam. 4. Liotiidae.— Epipodial line with a lobe behind each eye-peduncle, shell solid, trochiform, longitudinally ribbed or trellised, aperture round, operculum multispiral, hispid, corneous, with a calcareous layer. Silurian Principal genera: Inotia, Craspedostoma (Silurian), Crossostoma (Jurassic). Fam. 5. Trochidae. —Snout short, broad, frontal lobes often present, epipodial line furnished with cirrhi; shell nacreous, variously spiral, operculum corneous, multispiral, nucleus central (Fig. 182, p. 268). Silurian G.) Trochinae.— Frontal lobes present, lateral teeth (= side centrals) 5 only, no jaws, peristome incomplete. Prin- cipal genera: Trochus (subg. Cardi- nalia, Tectus, Infundibulum, Clan- culus), Monodonta (subg. Diloma), Fic. 270. — Monodonta canali- Cantharidus (subg. Bankivia, Tha- Jera Lam., New Ireland. Jotig), Gaza (subg. Microgaza), Cal Uli ee foie OMorosteatel (ii.) Gibbulinae. — Frontal lobes and jaws present, laterals often more than 5, peristome incomplete. Principal genera: Gid- bula (subg. Monilia, Aphanotrochus, Enida), Minolia, Circulus, Trochiscus, Livona, Photinula, Margarita, Solariella, Calli- ostoma, Turcica, Basilissa, Euchelus (subg. Olivia, Perrinia). (iii.) Delphinulinae.— No frontal lobes, jaws present; shell solid, XIV DIOTOCARDIA — RHIPIDOGLOSSA 409 surface spirally lirate, scaly, spinose, umbilicate, peristome con- tinuous. Single genus, Delphinula. (iv.) Umboniinae.— Eyes pedunculate, left tentacle attached to a frontal appendage, mantle reflected over edge of aperture, lateral teeth 6 on each side; shell polished, peristome incomplete, umbilicus generally closed by a callosity. Principal genera: Umboniuwm, Ethalia, Isanda, Camitia, Umbonella, Chrysostoma. Fam. 6. Turbinidae.— Epipodial line with slender cirrhi, snout broad, short, eyes pedunculate at outer base of tentacles, a frontal veil between tentacles; shell turbinate, solid, aperture continuous, operculum solid, calcareous, usually paucispiral, convex exteriorly (Fig. 182, p. 268). Silurian G.) Phasianellinae.— Shell bulimoid, polished, not nacreous, coloured in patterns, aperture oval. Single genus, Phaszanella (Fig. 271). Gi.) Turbininae. — Shell very solid, nacreous within, aperture circular or long oval. Principal genera, Turbo, whorls rounded above and below, spines, if present, becoming more prominent with age, operculum smooth or granulose, nucleus sub-central; subg. Callopoma, Ninella, Mar- morostoma, Sarmaticus, Prisogaster ; Astraliwm, whorls flattened above and below, spines, if present, becoming less prominent with age, operculum oblong, often excavated at centre, last whorl large, nucleus marginal or sub-marginal; subg. Lithopoma, Imperator, Guildfordia, Bolma, Cyclocantha, Uvanilla, Cookia, Pomaulax, Pachypoma. (ii.) Cyelo- nematinae.—Shell nacreous, umbilicate, operculum conical outside, whorls scalari- form. Principal genera: Cyclonema, Hori- ostoma (?), Amberleya (Silurian to Lias). Civ.) Leptothyrinae.— Shell small, solid, de- pressed, operculum nearly flat, nucleus sub- central. Genera: Leptothyra, Collonia (?). Fam..7. Neritopsidae.— Tentacles wide apart, long, eyes on short peduncles at the outer base; shell solid, neritiform or naticoid, aperture semi-lunar or oval; operculum (Fig. 183, p- 269) thick, calcareous, NOD 4 | ie pee at spiral, exterior face smooth, interior face tralis Gmel., Australia. divided into two unequal parts, with a broad median appendage. Devonian Principal genera: Neri- topsis (one recent species), Waticopsis (Devonian to Miocene). 410 DIOTOCARDIA — RHIPIDOGLOSSA CHAP. Fam. 8. Macluritidae.—Shell discoidal, whorls few, longi- tudinally grooved behind, right side convex, deeply umbilicated, left side flat; operculum very thick, nucleus excentrical, internal face with two apophyses, one very large. ‘The general appearance is more that of an inequivalve bivalve, such as Requiema, than of a spiral gasteropod. Palaeozoic Single genus, Maclurea. Fam. 9. Neritidae.—Snout short, tentacles long, eyes pedun- culate at their outer base, branchia triangular, free at the front end, epipodium without cirrhi, penis near the right tentacle; shell solid, imperforate, turbinate to almost patelliform, spire short, internal partitions absorbed (p. 168), columellar region broad, edge simple or dentate, operculum calcareous, spiral or non-spiral, with prominent apophyses on the interior face, one of which locks behind the columellar ip. Jurassic Prin- cipal genera: Merita (Fig. 18, p. 17); Neritena (chiefly brackish water and fluviatile), sub-genus Clithon, usually coronated with spines; Velates (Tertiary), Meritoma (Jurassic), Deianira (Cre- taceous), Septaria (=Navicella), shell more or less narrowly patelliform, with terminal apex, aperture very large, with a broad columellar septum, operculum too small for the aperture,. more or less covered by the integument of the foot; fluviatile only; Pileolus (Jurassic to Cretaceous). Fam. 10. Hydrocenidae. — Branchia replaced by a pulmonary chamber, eyes at the outer base of the tentacles, marginals of the radula very oblique, centrals often wanting; shell small, conical, whorls convex, operculum calcareous, with a prominent apophysis. Recent. Principal genera: Hydrocena, Georissa. Fam. 11. Heliconidae.—Branchia replaced by a pulmonary chamber, heart with one auricle; shell globular, with a short spire, internal partitions absorbed; operculum without apophysis. Carboniferous . Principal genera: Helicina (Fig. 188, p. 21; subg. Alcadia, Schasicheila, Heudeia, Calybium), Eutrocha- tella (subg. Lucidella), Stoastoma, Bourcieria, Dawsonella (Car- boniferous). | Fam. 12. Proserpinidae.— Branchia replaced by a pulmonary chamber, mantle partly reflected over the shell, eyes sessile; shell depressed, discoidal, columella folded or truncated at the base, whorls with one or more internal plicae, internal partitions absorbed, no operculum. Eocene Single genus; Proser- pina, subg. Proserpinella, Cyane, Dimorphoptychia (Eocene), and Ceres (Fig. 180, p. 21). XIV MONOTOCARDIA — TAENIOGLOSSA 4IiI Sub-order II. Monotocardia. — Heart with one auricle, one ctenidium (the left), monopectinate, fused with the mantle (except in Valvata), one kidney, not receiving the genital products, nervous system somewhat concentrated, proboscis and penis usually present. (a) PrENOGLOsSA.— Radula with formula o.o.0, teeth similar throughout, outermost largest (p. 224). Fam. 1. lanthinidae. — Snout prominent, blunt, no eyes, shell helicoid, fragile, bluish, no operculum; eggs carried on a raft of vesicles attached to the foot (Fig. 42, p. 126). Pelagic only. Pliocene Genera: lanthina, Recluzia. Fam. 2. Scalartidae. — Shell long, turriculate, whorls often partly uncoiled, with longitudinal ribs and prominent lamellae, aperture circular, operculum spiral, corneous, animal carnivorous. Ordovician Principal genera: NScealaria, Hglisia, Hlas- moneura (Silurian), Holopella (Silurian to Trias), Aclis. (6) TAENIOGLOSSA. — Radula with normal formula 2.1.1.1.2, marginals sometimes multiplied (p. 223). SECTION I. PLATyPoDA.— Foot more or less flattened ven- trally. Fam. 1. Waticidae.— Foot very large, produced before and behind, propodium reflected upon the head, eyes absent or buried in the integument, central and lateral tooth of the radula tri- cuspid, middle cusp strong; shell globular or auriform, outer lip simple, operculum corneous or calcareous, nucleus excentrical. Carboniferous Principal genera: Natica, with many sub-genera; Ampullina (Tertiary); Amaura; Deshayesia (Ter- tiary); Sigaretus (Fig. 91, p. 186), shell auriform, last whorl very large, operculum much too small for the aperture. : Fam. 2. Lamellariidae. — Mantle reflected over more or less of the shell, shell delicate, no operculum. Eocene Prin- cipal genera: Lamellaria, shell completely internal, transparent, auriform; some species deposit their eggs on compound Ascidians (p. 74); Velutina, shell almost entirely external, paucispiral, with a thick periostracum; Marsenina, shell auriform, partly internal; Onchidiopsis, shell a membranous plate, internal. Fam. 8. Trichotropidae.— Branchial siphon short, eyes on the outer side of the tentacles; radula closely allied to that of Velutina; shell conical, last whorl rather large, periostracum thick and hairy, operculum blunt claw-shaped, nucleus terminal. Cretaceous Genera: Trichotropis, Torellia. 412 MONOTOCARDIA — TAENIOGLOSSA CHAP. Fam. 4. Naricidae.— Tentacles broad in the middle, with sessile eyes at the exterior base, propodium narrow, quadrangular, a large epipodial veil on each side of the foot; shell naticoid, cancellated, with velvety periostracum. Jurassic Single genus: Narica. Fam. 5. Xenophoridae. — Foot divided by a groove, anterior portion the larger; central tooth heart-shaped, with blunt cusps, lateral large, roughly triangular, marginals long, falciform; shell trochiform, somewhat flattened, attaching various fragments externally. Devonian Single genus, Xenophora (Figs. 25, 26, p. 64). Fam. 6. Capulidae. — Ctenidium deeply and finely pectinate, visceral sac scarcely spiral, penis long, behind the right tentacle; shell roughly patelliform, with scarcely any spire, interior polished, usually with a septum or internal plate of variable form, no operculum. Devonian Principal genera (Fig. 155, | p. 248) ; Capulus, shell cap-shaped, no internal plate ; Platyceras (Palaeozoic, see p. 76), Diaphorostoma (Palaeozoic), Addisonia (?); Crucibulum, internal appendage funnel-shaped; Crepidula (including Crepipatella and Hrgaea), shell slipper-shaped, with a large septum; Calyptraea (including Galerus and Tro- chita), internal lamina semi-spiral. Fam. 7. Hipponycidae.— Foot aborted, animal sedentary, adductor-muscle shaped like a horse’s hoof, fastened on the ven- tral side to the region of attachment, or Fra. 272. —Two specimens of t0 @ thin calcareous plate which closes Crepidula (marked a and the aperture like a valve; ventral side of Tien rim © the body surrounded by a mantle with papillose border, which corresponds mor- phologically to the epipodia, head emerging between the dorsal and ventral mantles. Shell thick, bluntly conical, surface rugose. Eocene ——. Genera: Hipponyx; Mitrularia, a narrow half funnel-shaped appendage within the shell. Fam. 8. Solartidae. — Foot large, eyes sessile, near the outer base of the tentacles, radula abnormal (p. 224); shell more or less depressed, lip simple, umbilicus wide, margins often crenulated, operculum variable. The proper position of the family is quite uncertain. Ordovician Gi.) Solartinae. Genera: Sola- XIV MONOTOCARDIA — TAENIOGLOSSA 413 rium, shell depressed, highly finished, angular at periphery, operculum corneous, central tooth absent, laterals and marginals num- erous, long, and narrow; Platy- schisma (Silurian). (i.) Toriniinae. Genera: Torinia, whorls usually rounded, operculum (Fig. 183) conically elevated, spiral externally, central tooth present, marginals few, edge pectinated; Omalazis. (iii.) Huomphalinae, shell planorbiform, whorls rounded. Genera: Huomp ha- Fia. 273. — Solarium perspectivum lus, Ophileta, Schizostoma, Eccyliom- Lam., Eastern Seas. phalus (all Palaeozoic). Fam. 9. Homalogyridae. —- Tentacles absent, eyes sessile, central tooth unicuspid on a quadrangular base, laterals and marginals replaced by an oblong plate; shell very small, planor- biform. Recent. Single genus: Homalogyra, whose true posi- tion is uncertain. Fam. 10. Jnttorinidae.— Proboscis short, broad, tentacles long, eyes at their outer bases, penis behind the right tentacle; reproduction oviparous or ovoviviparous, radula very long; shell turbinate, solid, columella thickened, lip simple, operculum cor- neous, nucleus excentrical. Jurassic Principal genera: Lrttorina (radula, Fig. 16, p.20), Cremnoconchus (p. 16), Fossa- rina; Tectarius, shell tubercled or spinose; fzsella, base slightly concave ; Lacuna, shell thin, grooved behind the columellar lip. Fam. 11. Fossaridae. — Shell turbinate, solid, small, white, spirally ribbed, outer lip simple. Miocene Principal genus, Fossarus. _ Fam. 12. Cyclophoridae.—Ctenidium replaced by a pulmo- nary sac, tentacles long, thread-like (radula, Fig. 17, p. 21); shell variously spiral, peristome round, often reflected, operculum circular. Terrestrialonly. Cretaceous G.) Pomatiasinae, shell high, conical, longitudinally striated, operculum consisting of two laminae united together. Single genus, Pomatias. (ii.) Diplommatininae, shell more or less pupiform, peristome thick- ened or reflected, often double. Genera: Diplommatina (subg., Miecida, Palaina, Paxillus, Arinia), shell dextral or sinistral, small, columella often denticulated; Opisthostoma (Fig. 208, p. 414 MONOTOCARDIA — TAENIOGLOSSA CHAP. 309), last whorl disconnected, often reflected back upon the spire. (iii.) Pupininae, shell more or less lustrous, bluntly conical, lip with a channel above or below. Genera: Pupina (subg., Registoma, Callia, Streptaulus, Pupinella, Anaulus), Hybo- eystis (Fig. 205, p. 805), Cataulus, Coptochilus, Megalomastoma. Civ.) Cyclophorinae, shell turbinate or depressed, operculum corne- ous orcalcareous. Genera: Alycaeus, Craspedopoma, Leptopoma, Lagochilus, Cyclophorus (Fig. 206, p. 306; including Diadema, Aulopoma, Ditropis, and others), Aperostoma Cncluding Cyrto- toma and others), Cyathopoma, Pterocyclus (subg., Myzxostoma, Spiraculum, Opisthoporus, and Khiostoma (Fig. 180, p. 266), Cyclotus, Cyclosurus, and Strophostoma. Fam. 18. Cyclostomatidae. — Ctenidium replaced by a pul- monary sac, tentacles obtuse, foot with a deep longitudinal me- dian groove ; central tooth, lateral, and first marginal more or less bluntly cusped, second marginal large, edge pectinate; shell variously spiral, spire usually elevated, aperture not quite circular; operculum generally with an external calcare- ous and an internal cartilaginoid lam- ina, rarely corneous. ‘Terrestrial only. _ Cretaceous Genera: Cyclostoma - Gubg., Leonia, Tropidophora, Rochebrunia, Fie. 274.—Cyclostoma cam- Georgia, Otopoma, Lithidion, Revoilia), peli es Fir, Mada Oyelotopsis, Choanopoma (subg., Licina, Jamaicia, Ctenopoma, Diplopoma, Adam- stella), Cistula (sube., Chondropoma, Tudora), Omphalotropis (subg., Realia, Cyclomorpha), Hainesia, Acroptychia. | Fam. 14. Aciculidae.— Ctenidium replaced by a pulmonary sac, tentacles cylindrical, pointed at the end, eyes behind their base, foot long and narrow; central tooth and lateral very similar, pinched in at the sides, external marginal broad, edge finely pec- tinate ; shell small, acuminate, with a blunt spire, operculum corneous. ‘Terrestrial only. Tertiary Genus, Acicula (=Acme). Fam. 15. Truncatellidae.—Ctenidium replaced by a _ pul- monary sac, proboscis very long, eyes sessile, behind the base of the tentacles, shell small, evenly cylindrical, apex truncated in the adult. Eocene Genera: Zruncatella (subg., Taheitia, Blanfordia, and Tomichia), Geomelania (subg., Chittya and Blandiella), Cecina (?). XIV MONOTOCARDIA — TAENIOGLOSSA 415 Fam. 16. Rissoidae.— Eyes at the external base of the tentacles, epipodium with filaments, operculigerous lobe with appendages; central tooth pleated at the basal angles, lateral large, bluntly multicuspid, marginals long, narrow, denticulate at the edge; shell small, acuminate, often elaborately sculptured, ‘mouth entire or with a shallow canal, operculum corneous. Marine or brackish water. Jurassic Principal genera: fiissoa (subg., Folinia, Onoba, Alvania, Cingula, Nodulus, Anaba- thron, Fenella, Iravadia, and others), Scaliola (shell agglutinating fragments of sand, etc.), Rissoina (lip thickened, operculum with an apophysis as in Werita), Barleeia, Paryphostoma (Eocene). Fam. 17. Hydrobiidae.— Eyes at the outer base of the tentacles, penis behind the right tentacle, prominent, operculiger- — ous lobe without filaments; radula rissoidan, central tooth often with basal denticulations; shell more or less acuminate, small, aperture entire, operculum corneous or calcareous. Brackish or fresh water. Jurassic Principal genera: Baicalia, with its various sub-genera (p. 290); Pomatiopsis, Hydrobia, Bithy- nella, Micropyrgus (Tertiary), Pyrgula, Emmericia, Benedictia, Lithoglyphus, Tanganyicia, Limnotrochus (?), Jullienia, Pachy- drobia, Potamopyrgus, Littorinida, Amnicola, Fluminicola (subg., Gillia, Somatogyrus), Bithynia, Fossarulus (Tertiary), Stenothyra. Fam. 18. Assiminecdae.—Ctenidium replaced by a pulmonary sac, no true tentacles, eye-peduncles long, retractile ; radula that of Hydrobia; shell small, conoidal, operculum corneous, nucleus sub-lateral. Eocene Genera: Assiminea, Acmella. Fam. 19. Skeneidae.— Radula resembling that of Hydrobia ; shell very small, depressed, widely umbilicated, operculum corneous. Pleistocene Single genus, Skenea. Fam. 20. Jeffreysiidae.— Mantle with two pointed ciliated appendages in front, tentacles ciliated, eyes sessile, far behind the base of the tentacles; marginal teeth sometimes absent; shell small, thin, pellucid, whorls rather swollen, operculum with marginal nucleus, divided by a rib on the inner face. Recent. Genera: Jeffreysia, Dardania. Marine, living on algae. Fam. 21. Litiopidae.— Epipodium with cirrhi on each side, operculigerous lobe with appendages; radula rissoidan; shell . small, conical, columella truncated, operculum corneous. Eocene Genera: Litiopa, living on the Sargasso weed, suspended by a long filament; Alaba, Diala. — 416 MONOTOCARDIA — TAENIOGLOSSA CHAP. Fam. 22. Adeorbidae.— Radula essentially rissoidan; shell depressed, circular or auriform, widely umbilicated, opercu- lum corneous, paucispiral, nucleus excentrical. Pliocene Principal genera: Adeorbis, Stenotis, Megalomphalus. Fam. 23. Viviparidae.—Snout blunt, tentacles long, right tentacle in the male deformed, pierced with a hole corresponding to the aperture of the penis, two cervical lobes, the right being siphonal, foot with an anterior transverse groove; teeth broad, shallowly pectinate at the ends; shell turbinate, whorls more or less rounded, aperture continuous, operculum corneous, nucleus sub-lateral, with a false sub-central nucleus on the external face. Animal ovoviviparous. Fresh water. Cretaceous Genera: Vivipara (= Paludina), subg., Cleopatra, Melantho, Tulotoma; Tylopoma (Tertiary), and Lroplaz. Fam. 24. Valvatidae. — Branchia exserted, bipectinate, carried on the back of the neck, a filiform appendage (Fig. 66, p. 159) on the right of the neck, penis under the right tentacle, prominent, eyes sessile, behind the tentacles; radula like that of Vivipara; shell small, turbinate or flattened, operculum corneous, nucleus central. Fresh water. Jurassic———. Single genus, Valvata. Fam. 20. Ampullariidae.—Snout with two tentacles, ten- tacles proper very long, tapering, eyes prominently pedunculate, two cervical lobes, the left siphonal, respiratory cavity divided by a partition, a large branchia in the right chamber, the left functioning as a pulmonary sac (Fig. 65, p. 158); radula large, central tooth multicuspid, base broad, lateral and marginals falei- form, simple or bicuspid; shell large, turbinate or flattened, spire small, whorls rounded; operculum generally corneous, nucleus sub-lateral, false nucleus asin Vewpara. Fresh water. Cretaceous Single genus, Ampullaria (subg., Ceratodes, Pachylabra, Asolene, Lanistes, and Meladomus). Fam. 26. Cerithiidae.—Branchial siphon present, short, eyes variable in position; central tooth small, evenly cusped, lateral hollowed at base, multicuspid, marginals narrow; shell long, turriculate, whorls many, generally tuberculate, varicose or spiny, aperture sometimes strongly channelled; operculum corneous, sub-circular, nucleus nearly central. Marine or brackish water. ‘Trias Principal genera: Z'riforis, shell small, generally sinistral; Fastigiella, Cerithium (Fig. 12, p. 16), Bittium, Potamides (subg., Tympanotomus, Pyrazus, Pirenella, Telescopium, Cerithidea, Lampania, all brackish water), Diastoma XIV MONOTOCARDIA — TAENIOGLOSSA 417 (Eocene), Cerithiopsis; Ceritella (Jurassic), Brachytrema (Jurassic), and Planazis (subg., Quoyia and Holcostoma). Fam. 27. Modulidae.—No siphon, radula of Cerithium; shell with short spire, columella strongly toothed at the base, aperture nearly circular. Recent. Single genus, Modulus. Fam. 28. Nerineidae.—Shell solid, long, sub-cylindrical, aperture channelled, columella and interior of whorls with continuous ridges, extending up the spire. Genera: Nerinea (Trias to Cretaceous), Aptyxiella (Jurassic). Fam. 29. Melaniidae.— Border of mantle festooned, foot broad, with an anterior groove, penis present; radula closely re- sembling that of Cerithiwm; shell long, spiral, with a thick peri- ostracum, surface with tubercles, ribs, or striae, suture shallow; operculum corneous, paucispiral, nucleus excentrical. Animal ovoviviparous. Fresh water. Cretaceous Principal genera: Melania (with many sec- tions or sub-genera), Pachychilus, Claviger (= Vibex), Hemisinus, Pirena, Melanopsis, Tiphobia, Paludomus (sube., Philopotamis, Tanalia, Stomatodon), Hant- kenia (Kocene), Larina (?). Fam. 80. Pleuroceridae.— Mantle edge not fes- tooned, no copulatory organ, otherwise like Melanii- dae; operculum with nucleus sub-marginal. Animal oviparous. Freshwater. Cretaceous Sy Getendi vere oon sl ge Pleurocera (including Jo, Fig. 12, p. 16, Angi- lania con- trema, Lithasia, Strephobasis), Goniobasis, Anculotus, eee Gyrotoma. Fam. 31. Pseudomelanidae.—Shell resembling that of Melaniidae, but marine. Genera: Pseudomelania, Loxonema, Bourguetia, Macrochilus. Palaeozoic to Tertiary strata. Fam. 82. Turritellidae.— Mantle with a siphonal fold on the right side; radula variable (p. 224); shell long, whorls many, slowly increasing in size, transversely ribbed or striated, aper- ture small; operculum corneous, nucleus central. Jurassic : Principal genera: Turritella, Mesalia, Protoma, Mathilda (?). Fam. 33. Coecidae.—Tentacles long, eyes sessile at their base; shell small, spiral in the young form, spire generally lost in the adult, the shell becoming simply a straight or curved cylinder; operculum corneous, multispiral. Eocene Single genus, Coecum. VOL. III 2E 418 MONOTOCARDIA — TAENIOGLOSSA CHAP. Fam. 34. Vermetidae.— Visceral sac greatly produced, irregularly spiral, no copulatory organs (radula, Fig. 126, p. 223), shell tubular, irregularly coiled, last whorls often free, aperture circular; operculum corneous, circular, nucleus central. Carbo- niferous Principal genera: Vermetus ; Siliquaria (Fig 1538, p. 248), a long fissure, @ or series of holes, runs along a considerable part of the shell, operculum with outer face Fie. 276. — Develop- spiral, elevated. TLE Fam. 85. Strombidae.—Foot narrow, arched, formation of septa; metapodium greatly produced, snout long, eye a, apex; ap, aper- | : 5 ture; ss, first sep- peduncles long, thick, eyes elaborate, siphon tum; 8's’, second short, penis prominent, bifurcate; central tooth septum. (After de . ; c =e Folin.) B, adult With strong median cusp, marginals falciform, jorm orc. eburneum slender, edge more or less denticulate; shell ., Panama. x10. : : : : : solid, spire conical, outer lip generally dilated into wings or digitations, channelled before and behind, a labial sinus at the base, distinct from the anterior canal; operculum small for the aperture, corneous, claw-shaped, edge notched. Lias Genera: Strombus (Fig. 99, p. 200); Peretraea (Miocene), Pteroceras (Fig. 277; digitations of the outer lip very strong), ostellaria (spire produced, anterior canal very long), Rimella, Pterodonta, Terebellum (base of shell truncate, spire short). Fam. 36. Chenopodidae (= Aporrhaidae).— Foot flat; lateral and marginal teeth not denticulate; shell resembling that of Strombus, outer lip dilated, wing-like, no labial sinus. Jurassic Genera: Chenopus (= Aporrhais, Diastema, Malaptera, Harpagodes, Alaria (last four from Secondary strata). Fam. 87. Struthiolariidae.—Radula allied to that of Strombus, marginals occasionally multiplied; shell buccinoid, very solid, outer lip thickened, canal short, operculum claw-shaped, notched, nucleus terminal. Tertiary Single genus, Struthiolaria (subg., Perissodonta, marginal teeth multiplied). Fam. 88. Cypraeidae.— Mantle with two large lateral lobes reflected and meeting over the shell, siphon small; central and lateral teeth bluntly tricuspid or multicuspid, laterals fairly broad, edges cusped or finely pectinate; shell polished, solid, spire generally concealed in the adult or overlaid with enamel, aperture straight, narrow, nearly as long as the shell, toothed at — <<", XIV MONOTOCARDIA — TAENIOGLOSSA AIQ the sides, channelled at each end, labium inflected ; no opercu- lum. Jurassic Genera: Ovula (including Amphiperas, Transovula, Cyphoma, Radius, Simnia), Pedicularia, Cypraea (with sube., Cypraeovula, Cypraedia, and Trivia), and Hrato. Fam. 39. Dolzidae. — Foot expanded, wider and longer than the shell, truncated and thickened in front, siphon very long and narrow ; central tooth with very strong median and small lateral Fic. 277. — Three stages in the growth of Pteroceras rugosum Sowb., E. Indies, showing the development of the ‘ fingers.’ and basal cusps, lateral and marginals bluntly falciform ; shell ventricose, without varices, spire short, outer lip generally simple, anterior canal rather wide, no operculum. Cretaceous : Genera: Dolium (subg., Malea, outer lip thickened, denticulate, reflected) ; Pirula, mantle with two lateral lobes reflected over part of the shell, shell fig-shaped (Fig. 278). Fam. 40. Cassididae. — Foot broad, siphon long (radula, Fig. 125, p. 223); shell ventricose, with varices, spire short, outer lip reflected or thickened, anterior canal short, recurved narrow; operculum semilunar, with ribs radiating from a marginal 420 MONOTOCARDIA — TAENIOGLOSSA CHAP. nucleus. Cretaceous Genera: Cassis (subg., Semicassis and Cypraecassis), Morio (= Cassidaria), Oniscia. Fam. 41. Columbellinidae.— Shell solid, ribbed, usually can-_ cellated, with an oblique posterior canal, columella callous, more or less reflected. Genera: Columbellina, Columbellaria, Zittelia, Petersia, Alariopsis (?). Secondary strata only. Fam. 42. Tritonidae. — Foot short, narrow; siphon short, not prominent; radula allied to that of Cassididae; shell thick, varicose; outer lip inflected and thickened, canal long, perios- tracum often thick and hairy, operculum corneous, nucleus terminal or sub-marginal. Cretaceous Genera: Triton (Fig. 191, p- 275; subg., Hpidromus, Plesiotriton, Sim- pulum, Ranularia, Argobuccinum) ; Persona, aperture toothed, narrow; columella reflected upon the last whorl; Ranella, shell dorso- ventrally compressed, generally with two con- tinuous lateral varices, posterior canal present. The position of the following four families is doubtful: — Fam. 48. Oocorythidae.— Siphon short, foot broad, eyes absent, radula taenioglossate ; eee SE arate shell buccinoid or cassidiform, operculum cor- +» Philip pines. x. neous, spiral. Recent. Single genus, Oocorys. Fam. 44. Subulitidae.— Shell elongate, fusiform, smooth; suture shallow, base truncate or rounded, aperture channelled or notched. Ordovician to Trias. Genera: Subulites, Fusispira, Huchrysallis. Fam. 45. Seguenzvidae.— Radula taenioglossate, shell trochi- form, aperture channelled, columella twisted, operculum multi- spiral, nucleus central. Pliocene Single genus, Seguenzza. Fam. 46. Choristidae.— Anterior tentacles united bya frontal veil, posterior simple ; eyes absent, foot with tentaculae before and behind; three central teeth, outer marginal with a basal plate; shell helicoid, suture deep, peristome continuous, operculum corneous, paucispiral. Pliocene Single genus, Choristes. Section II. HetrrropopA. — Foot fin-shaped, not flat. The Heteropoda are free-swimming Mollusca, being, like the Pteropoda, Gasteropoda modified to suit their pelagic environ- ment. Their nervous system is streptoneurous, and they are XIV HETEROPODA 421 therefore probably derived from the Prosobranchiata, but they are highly specialised forms. Pelseneer considers them far more widely removed from the Streptoneura than the Pteropoda are from the Euthyneura. They swim on the surface “upside down,” 2.e. with the ventral side uppermost. The tissues and shell are transparent, permitting observation of the internal organs. In the Pterotrachaeidae the foot takes the form of a fan-shaped disc, usually furnished with a sucker. The body is compressed at the posterior end, often with a ventral “fin.” In Atlanta the foot consists of three very distinct parts: a propodium, a mesopodium, on which is a small sucker, and a metapodium, which carries the operculum. The branchiae are carried on the visceral sac, and are free in Pterotrachaea, slightly protected by the shell in Carinaria, and entirely covered in Atlanta ; absent altogether in Mroloida. The head carries two tentacles (except in Pterotrachaea), with large, highly organised eyes on short lobes at their outer base. The alimentary tract consists of a long protrusible pro- boscis, with a taenioglossate radula (Fig. 132, p. 227), a long oesophagus, and a slightly flexured intestine. In Atlanta the visceral sac is spiral and protected by a spiral planorbiform shell; in Carinaria the visceral sac is small, conical, protected by a very thin capuliform shell. There is no shell in Ptero- trachaea or Firoloida. The Heteropoda are dioecious. In the male there is a flagellum behind the penis, which is near the middle of the right side. Pterotrachaea lays long chains of granular eggs, and has been noticed to produce a metre’s length in a day. The eggs of Atlanta are isolated. The embryo has a deeply bilobed velum. | Fam. 1. Pterotrachaeidae.— Body long, with a caudal “fin ;”’ branchiae dorsal, free or partly protected by a shell; foot consist- ing of a muscular disc, with or without a sucker. Pterotrachaea proper has no mantle, shell, or tentacles. The branchiae are disposed round the visceral sac, at the upper part of which is the anus. In Firoloida the body is abruptly trun- cated behind, with a long filiform segmented caudal appendage ; visceral sac at the posterior end: fin-sucker present or absent in both male and female. Cardiapoda resembles Carinaria, but the visceral sac is more posterior and is only slightly protected by AZ2 MONOTOCARDIA — GYMNOGLOSSA — RACHIGLOSSA CHAP. a very small spiral shell. Carimaria (Fig. 279) has a rugose translucent skin, visceral sac sub-median, apparently peduncu- lated, covered by a capuliform shell. The larval shell, which persists in the adult, is helicoid. Fam. 2. Atlantidae.— Shell spiral, operculate, covering the animal. Branchiae in a dorsal cavity of the man- tle; foot trilobed, with a small sucker on the meso- podium. The shell of Atlanta is discoidal and_ sharply keeled, while that of Ozy- gyrus is nautiloid, with the Fic. 279.—Carinaria mediterranea Lam., spire concealed, ne keel, Naples: a, anus; br, branchiae; /, foot; i, aperture dilated. tecine: mi moutls Bpamlss & sock (4) Gy OER Radula and jaws absent; proboscis prominent, sexes probably separate, penis present. The section is probably artificial and unnecessary, the families composing it being, in all probability, Taenioglossa which have lost their radula in consequence of changed conditions of life (pp. 79, 225). Fam. 1. Hulimidae. — Proboscis very long, retractile, mantle forming a siphonal fold; shell small, long, subulate, polished; suture shallow, aperture continuous, operculum present or absent. Animal often parasitic, sucking the juices of its host by its long proboscis. ‘Trias Genera: Hulima (subg., Subularia Ar- cuella, Apicalia, Mucronalia, Stiliferina, and others), Stilifer, Scalenostoma, Niso, and Hoplopteron. Fam. 2. Pyramidellidae. — Tentacles auriform, proboscis as in Eulimidae, a prominent mentum or flap under the buccal orifice ; shell usually small, conical; suture shallow, apical whorls (the embryonic shell) sinistral (p. 250), operculum corneous, pauci- spiral; nucleus excentrical. ‘Trias Genera: Pyramidella (sube., Syrnola, Otopleura, Chrysallida, Mumiola), Odostomia, Eulimella, Murchisoniella, Turbonilla (subg., Dunkeria and Cingulina. (d) RAcHIGLOSSA (p. 220).— Proboscis long, retractile ; siphon distinct, radula without uncini, sometimes without laterals ; teeth strongly cusped; shell generally wholly external. XIV MONOTOCARDIA — RACHIGLOSSA A23 Fam. 1. Muricidae.— Eyes sessile at the outer base of the tentacles, penis large, behind the right tentacle, radula within the retractile proboscis, central tooth (Fig. 119, p. 220) with at least three strong cusps, laterals plain; shell solid, more or less tuberculate, spiny and varicose, anterior canal varying from a mere notch to a long channel. Cretaceous Principal genera: G.) Muricinae, nucleus of operculum sub-terminal ;. 7'ro- phon, Typhis, Murex (with many subdivisions), Ocinebra (includ- ing Cerastoma, Vitularia, and Hadriania), Urosalpinx, Eupleura, Pseudomurea. (il.) Purpurinae, nucleus of operculum lateral ; Rapana Gnecluding Latiaxis), Purpura (with sube., Cuma, Lopas, Vexilla, and Pinaxia), Monoceros Gncluding Chorus), Purpu- roidea (Secondary strata), Pentadactylus, Sistrum, Concholepas. Fam. 2. Coralliophilidae. — Animal living in Madrepores, resembling Purpura, radula absent; shell variously shaped, often deformed or tubular, operculum that of Purpura, if present. Miocene Principal genera: Lhizochilus, Co- ralliophila, Leptoconchus, Magilus (Fig. 29, p. 15), Rapa. Fam. 8. Columbellidae. — (Radula, Fig. 128, p. 222.) Shell small, solid, fusiform, aperture narrow, canal short, outer lip thickened. Miocene Single genus, Colwmbella (subg., Nitidella, Anachis, Meta, Strombina, Atilia, Conidea, Amphissa, Mitrella, and others). | Fam. 4. Nassidae.— Foot long and broad, often with terminal appendages; siphon long, eyes on outer base of tenta- cles, central tooth of radula arched, multicuspid, lateral strongly bicuspid, with small denticles between the cusps; shell rather small, buccinoid, columella more or less callous, outer lip thick- ened, often toothed; operculum corneous, edges often toothed. - Miocene Principal genera: Nassa (with many sections), Amycla, Desmoulea, Cyclonassa, Canidia (subg., Clea and Nasso- donta), Dorsanum, Bullia (=Buceinanops, Fig. 62, p. 185), Truncaria. Fam. 5. Auccinidae. — Siphon rather long, eyes at outer base of tentacles; central tooth of radula with 5 to 7 cusps, laterals bicuspid or tricuspid (Fig. 118, p. 220); shell more or less fusi- form, thick, covered with a periostracum, canal of varying length, outer lip simple or thickened; operculum corneous, nucleus variable in position. Cretaceous Principal genera: Group 1. Chrysodomus (with sections Veptunea, Volutopsis, Pyrolofusus, 424 MONOTOCARDIA — RACHIGLOSSA CHAP. Jumala), subg., Sipho; Stphonalia (subg., Kelletia). Group ii. Tiomesus (= Buecinopsis). Group iii. Buccinum (Fig. 1B, p. 6; subg., Volutharpa, Neobuccinum). Group iv. Cominella, Triton- idea, Pisania, Huthria ; Anwra (Miocene), Genea (Pliocene), Metula, Hngina. Group v. Phos, Hindsia. Group vi. Dipsaceus (= Hburna), Macron. Group vii. Pseudoliva. Fam. 6. Turbinellidae. — Central tooth of radula tricuspid, median cusp strong, lateral bicuspid, cusps unequal (Fig. 117, p. 220) ; shell fusiform or pear-shaped, heavy, canal often long, operculum corneous, claw- shaped, nucleus terminal. Miocene Principal genera: Turbinella, Cynodonta, Tudicla (subg., Streptosiphon) ; Piropsis (Cretaceous), Perissolax (Cretaceous), Fre. 280.— Turbinella pyr- Strepsidura (HKocene, subg., Whitneya), wn Tam., Ceylon. *3- Melapium, Fulgur (=Busycon, Fig. 150, p. 249, including Syecotypus), Melongena (subg., Pugilina, Myristica); Lniostoma (Eocene), Hemifusus (subg., Megala- tractus), Ptychatractus, Meyeria. Fam. 7. Fasciolaruidae. — Eyes at the outer base of the tenta- cles (radula, Fig. 121, p. 221); shell fusiform, spire long, canal often very long, columella often with a fold at the base; operculum corneous, nucleus terminal. Cretaceous . Principal genera: Fusus Gncluding Sinistralia, Aptyxis, Troschelia), with sube., Serri- fusus (Cretaceous), Clavella (subg. Thersites), Fasciolaria, Latirus (subg. Polygona, Peristernia, Leucozonia, La- gena; Mazzalina (Eocene), Chascaz). Fam. 8. Mitridae.— Siphon rather long, with anterior appendages, eyes on the side of the tentacles, proboscis . very long; radula variable, laterals F a pate (Leucommaa sometimes lost (Fig. 120, p. 221); shell fusiform, solid, spire more or less pointed, columella with several prominent folds, the posterior the largest, aperture rather XIV MONOTOCARDIA — RACHIGLOSSA 425 narrow, no operculum. Cretaceous Principal genera: Mitra (with many sections), subg., Strigatella, Mitreola, Mutyca, Dibaphus ; Plochelaea (Ter- tiary), Thala; Turricula (with several sec- tions), Cylindromitra, and Imbricaria. Fam. 9. Volutidae.— Foot broad in front, head laterally dilated into lobes, on which are placed the sessile eyes ; siphon prominent, with appendages at the base (radula, Fig. 122, p- 221); shell thick, often shining, fusiform, globular or cylindrical, columella projecting anteriorly, with several folds, the anterior of which is the largest, aperture notched, canal not produced, operculum generally absent. Fic. 282.— Voluta ni- Cretaceous vineipal) genera: \Crypto- ose. Lams West ‘ aaa ustralia. x 2. chorda (Eocene), Zidona, Provocator, Guivil- lea, Yetus (= Cymbium), Voluta (with many sections), Voluto- lithes (chiefly Eocene), Volutolyria, Lyria, Enaeta, Volutomitra. Fam. 10. Marginellidae.— Foot broad, siphon without ap- pendages, mantle largely reflected over the shell; radula with- out laterals, central tooth comb-like, cusps rather blunt; shell oval or conoidal, polished, aperture narrow, outer lip thickened, columella with many folds; no operculum. Eocene Prin- cipal genera: Marginella, with many sections and so-called sub-genera; Persicula, Pachy- bathron (2), Cystiscus, Microvoluta. Fam. 11. Harpidae.—Foot large, with a transverse groove, separating off a semi-lunar propodium; mantle partly reflected over the shell; shell ventricose, polished; spire short, strongly longitudinally ribbed, ribs prolonged over the suture, columella callous; no oper- : culum. Eocene Single genus, Harpa Fic. 283. — Oliva por- (subg., Stlia). s oe | Paw 12s Onmaa: —Propodium semi- lunar, with a longitudinal groove above, mesopodium reflected laterally over the shell; central tooth of radula tricuspid on a very broad base, lateral simple, hooked; shell sub-cylindrical or fusiform, polished; aperture narrow, 426 MONOTOCARDIA — TOXOGLOSSA operculum present or absent. Cretaceous CHAP. XIV Principal genera: Oliva (Figs. 283, and 98, p. 199), Olivancillaria (including lina). with a large poison gland ; rous, exclusively marine. the tentacles, shell subulate, many whorled, operculum with terminal nucleus. Eocene Single genus, Terebra, with several sec- tions. Fam. 2. Conidae.— Eyes on outer side of tentacles, E RO sion siphon prominent; shell conical or fusiform, aperture narrow. Cretaceous Principal genera: Conus, shell solid, spire short, aperture narrow, straight, internal par- titions partly absorbed; Conorbis, Genotia (with several sections, chiefly Tertiary), Pusionella, Columbarium, Clavatula, Surcula, Pleurotoma; Borsonia (HKocene), Drillia (sube., Spirotropis), Bela, Mangilia (including Daphnella, Clathurella, and others), Halia. LTintricula and Agaronia), Olivella, Ancilla (subg., Aneil- (e) ToxoGLossa (p. 218).— Radula with normal formula 1-0-1, teeth large ; oesophagus animal carnivo- Fam. 1. Terebridae.— Eyes at the end of Fic. 285. — Pleuro- toma tigrina Lam., E. Indies. Fam. 8. Cancellariidae.— Proboscis short, usually no radula, shell oval, columella strongly plicate; no operculum. Cretaceous Single genus, Cancellaria Trigonostoma, Admete). . (subg., Meriea, CHAPTER XV CLASS GASTEROPODA (continued): OPISTHOBRANCHIATA AND PULMONATA Order III. Opisthobranchiata VISCERAL loop not twisted (except in Actaeon) in a figure of 8 (Euthyneurous type, p. 203), auricle usually behind the ven- tricle, ctenidium often replaced by secondary branchiae, pallial cavity, if existing, more or less open, shell present or absent, operculum absent (except in Actaeon), animal hermaphrodite, with separate sexual openings, marine only. — Carboniferous to present time. : The character of their nervous system decisively removes the Opisthobranchiata from the Prosobranchiata, and approximates them to the Pulmonata. Actaeon, however, which is strepto- neurous, as well as possessing an operculate shell with prominent spire, forms an interesting link with the Prosobranchiata. At the opposite extreme to Actaeon stand forms like Siphonaria and Gadinia, which are probably close links with the Pulmonata (p. 19). The generative system of the whole group, which is, as in the Basommatophora, of the hermaphrodite type, without mutual fecundation, is another link of connexion with the Pulmonata. The respiratory organs present the most varied forms, sometimes consisting of one ctenidium (never two), some- times of secondary branchiae, variously placed, while sometimes no special organ exists. The prolongation of the foot into lateral epipodia or parapodia (possibly to aid in swimming), and the effect of the epipodia upon the shell, according as they involve it completely or par- tially, are among the most instructive features of the Opistho- branchiata. If the epipodia are developed on the anterior 427 428 OPISTHOBRANCHIATA CHAP. portion of the body, and do not become reflected, they may, as in most Pteropoda Thecosomata, not directly affect the shell. But when, as in the Tectibranchiata, the epipodia are medio- lateral, and tend to envelope the shell, their effect may be traced by a series of forms varying in proportion to the amount of shell-surface covered by the epipodia. The two principal lines along which modification takes place are the gradual reduction of the spiral nature of the shell, and the gradual lessening of its solidity. Both these changes are the direct Fia. 286. — Illustrating the transition Fic. 287.— Illustrating the gradual covering of form in the shell of Tecti- of the shell in the Tectibranchiata by the branchiata from the pointed spiral epipodia and mantle: A, Haminea; B, to the almost flattened plate: A, Scaphander ; C, Aplustrum; D, Aplysia; Actaeon; B, Aplustrum; C, Cyli- E, Philine; c.d, cephalic disc; ep, ep, chna; D, Atys; E, Philine; F, epipodia; sh, shell. (Not drawn to scale.) Dolabella; G, Aplysia; H, Pleu- robranchus. (Not drawn to scale.) result of the additional protection afforded to the visceral mass by the reflected epipodia, which renders the existence of a shell less and less necessary. A precisely similar line of change is seen 1n the Pulmonata, culminating in forms like Arion (p. 174). The habits of life of the Opisthobranchiata are very varied. Some, especially the heavier types, burrow in sand, and are then usually furnished with a broad cephalic disc, as a digging appa- ratus; some (certain Bulla) flit about in shallow pools on mud flats; others (Phyllirrhoe and the Pteropoda) swim freely in the open sea; others (most Nudibranchiata) crawl slug-like on sea-weeds or corallines, and in colour singularly harmonise with XV OPISTHOBRANCHIATA: HABITS, CLASSIFICATION 429 their environment (p. 71 f.) ; others again (Stphonaria, Gadinia), stick limpet-like to rocks between tide marks. As a rule, they occur only in clean salt water, but Hmbletonia has been found in the Victoria Docks at Rotherhithe, as well as in parts of the Baltic, where the water has only 7 parts of salt in 1000, while TInmapontia occurs in nearly fresh water at Bornholm and Gothland. Their food varies greatly. As a rule, they are frugivorous, but many cases of carnivorous habit occur. Scaphander has been seen to swallow Dentalium six at a time, and in six hours the shells of all were reduced to tiny fragments. Glaucus devours the soft portions of the pelagic Porpita and Velella; Idalia elegans eats its way into the test of Ascidians, and completely buries itself in the body of its prey.? The Opisthobranchiata may be classified as follows : — ( Bulloidea | A plysioidea | Pleurobranchoidea \ Siphonarioidea 1. TECTIBRANCHIATA y : 3. Nuprmrancmtata . | Cladohepatica | Holohepatica f Thecosomata | Gymnosomata | ome) 2. ASCOGLOSSA | 4, PTEROPODA L Sub-order I. Tectibranchiata. — Right ctenidium usually present, more or less concealed by the mantle fold, visceral ganglia united by a very long commissure, shell variable in form, more or less enveloped in folds of the mantle and foot, often becoming rudimentary. SECTION I. BULLOIDEA. — Shell more or less spiral, internal or external, epipodia more or less developed, a broad cephalic disc, distinct from the dorsal region, usually no tentacles, eyes sessile. Fam. 1. Actaeonidae.—Shell spiral, solid, entirely covering the animal; spire generally prominent, operculum corneous, visceral loop streptoneurous, no epipodia, radula multiseriate, teeth numerous, very small. Carboniferous Genera: Actaeon (Fig. 286 A); Volvaria (Tertiary), Fortisia (Eocene) 1J, Power, Ann. Mag. N. H. (2) xx. p. 384; P.Z S. 1836, p. 118; Arch. Zool. Exp. Gén. (8) i. 1893, p. 105. 430 | TECTIBRANCHIATA CHAP. Actaeonina (Carboniferous), Cylindrites (econdayy strata), Actaeonella (Cretaceous). Fam. 2. TYornatinidae.— Shell spiral, cylindrical, entirely covering the animal; spire concealed, cephalic disc with two large tentaculiform appendages behind, no radula. Genera: Tornatina (= Utriculus), Volvula. Fam. 8. Scaphandridae.—Shell more or less external, cover- ing all or nearly all the animal, spire concealed, cephalic disc simple or notched behind, epipodia well developed, radula with first lateral very large, stomach sometimes with powerful gizzard. Genera: Scaphander (Fig. 287 B); Sabatea (Pliocene), Smaragdt- nella, Atys (Fig. 286 D), Cylichna (Fig. 286 C), Amphisphyra. Fam. 4. Bullidae.—Shell external or partly internal, spire quite or nearly hidden, cephalic disc broad, without appendages, epipodia often large ; radula usually multiseriate. Genera: Bulla (subg. Haminea), Acera, mantle with long filiform appendage, epipodia touching over the shell; Cylindrobulla, Volvatella. Fam. 5. Aplustridae. — Shell partly internal, overlaid by the posterior part of the cephalic disc, spire not prominent, epipodia reflected, tentacles auriform. Single genus, Aplustrum (Fig. 286 B; subg. Hydatina). Fam. 6. Ringiculidae. — Shell small, solid, covering all the animal; spire.somewhat prominent, aperture narrow, plicated ; peristome thick, sometimes channelled, cephalic disc with a kind of posterior siphon. Genera: Ringicula ; Avellana (Cretaceous). Fam. 7. Gastropteridae.— Shell completely internal, nauti- loid, small; epipodia very large, rounded, united behind; cephalic disc simple. Single genus, Gastropteron. Fam. 8. Philintdae.— Shell completely internal, thin, slightly spiral ; epipodia thick, cephalic disc large, thick, simple; stomach _ usually with powerful gizzard. Genera: Philine (Fig. 287 E), Colpodaspis, Colobocephalus, Chelinodura, Phanerophthalmus, Cryptophthalmus. Fam. 9. Doridiidae.—Shell completely internal, a mere pellicle with a small spiral nucleus, mantle with two posterior lobes and a caudal filament, epipodia reflected. Single genus, Doridium. Section II. ApLystompBaA. — Shell small, usually not spiral, sometimes absent, no cephalic disc, head prominent, with two pairs of tentacles, epipodia large, more or less reflected. XV TECTIBRANCHIATA — ASCOGLOSSA | 431 Fam. Aplystidae.—Characters those of the section. Genera: Aplysia (Fig. 287 D), shell arched, flattened, animal large (the “sea hare”); Dolabella, shell sub-triangular (Fig. 286 F) ; Dola- brifer, shell sub-quadrangular, not spiral ; Wotarchus, shell micro- scopic, spiral; Phyllaplysia, body very depressed, oval, no shell. _ Section III. PLevUROBRANCHOIDEA.— Dorsal region pro- tected by a wide notaewm or dorsal covering, or by a shell; no epipodia, ctenidium large, external, between the right under surface of the notaeum or shell and the foot; head short, shell present or absent. Fam. 1. Pleurobranchidae.— Shell internal or absent, notaeum with spicules, radula multiseriate. Genera: Pleurobranchus (Fig. 286 H), (?) Haliotinella, Pleurobranchaea, (?) Neda. Fam. 2. Runecinidae.—Branchial lamellae few, under the posterior right notaeum, no shell. Single genus, Auneina. Fam. 3. Umbrellidae.—Shell external, depressed patelliform, not covering all the animal; foot very thick, ctenidium large, head depressed, small; radula multiseriate, teeth innumerable, very small. Genera: Umbrella (Fig. 5A, p. 10), Zylodina. SECTION IV. SIPHONARIOIDEA.— Shell patelliform, bran- chia replaced wholly or in part by a pulmonary sac, pulmonary orifice closed by a small lobe, radula multiseriate, teeth very small. : Fam. Siphonariidae. — Characters those of the section. Genera: Stphonaria (branchia as well as pulmonary sac), Gad- iia (no branchia). These genera, hitherto placed among the Pulmonata, have been recently shown (see p. 19) to be modified Opisthobranchiata. Sub-order II. Ascoglossa.!— Branchia, mantle cavity, and shell generally wanting, liver ramified, rami enclosed in external papillae (cerata) or beneath the dorsal surface, kidney not com- pact, branched ; radula with one series of strong teeth (Fig. 288), worn out teeth at the front end not dropping off, but preserved in a special sac (aoxcs). According to Bergh, the Ascoglossa form a link between the Tectibranchiata, — especially the Aplysiidae and Bullidae —and 1 In deference to Bergh’s high authority, the position of a sub-order is here given to the Ascoglossa. It may be doubted whether that position will stand the test of further investigation, and whether the families concerned will not be added to the Cladohepatic Nudibranchs. 432 ASCOGLOSSA — NUDIBRANCHIATA CHAP. ‘the Cladohepatic Nudibranchs, while the Pleurobranchidae form a somewhat similar ink between the Holohepatic Nudibranchs and the other Tectibranchiata. Fam. 1. Oxynoeidae1— Animal long, tentacles auriform, epipodia large, simple, or wing-like, a ctenidium and branchial chamber on right side, shell small, thin, slightly spiral, not covering much of the body. Genera: Ozxynoe (=Lopho- — cercus), Lobiger. Fam. 2. Hermaeidae.— Body de- pressed, cerata in several rows, no branchiae, no shell. Genera: Hermaea, Phyllobranchus, Stiliger, Alderia. Fic. 288.— Radula of one of Fam. 38. EHlysiidae. — Body depressed, ie ae viridis head rather elevated, tentacles auriform, sides of body dilated into two large wings, which enclose branches of the liver and sometimes fold over the dorsal surface, no branchiae, no shell. Genera: Hlysia, Thridachia, Placobranchus. Fam. 4. Limapontiidae. — Body slug-like, liver scarcely ramified, no branchiae, shell, or appendages. Genera: JLima- pontia, Actaeonia, Cenia. Sub-order III. Nudibranchiata. — Shell absent in the adult, no ctenidium proper, or osphradium, cerata dorsal or dorso-lateral, nervous system concentrated, kidney not compact, ramified, penis retractile, jaws and radula usually present. SECTION I. CLADOHEPATICA. — Cerata usually latero- dorsal, elongated, or arborescent, buccal mass strong, jaws present, liver generally ramified, rami generally entering the cerata. Fam. 1. Aeolidtidae. — Body slug-like, head with tentacles and rhinophores, dorsal area with rows of cerata, which usually contain sting-cells, radula variable. Genera: Aeolis, Cratena, Tergipes, Coryphella, Favorinus, Facelina, Flabellina, Fiona, Glaucus, Janus, Hero, with many sub-genera. Fam. 2. Tethymelibidae.— Body slug-like, large, cerata very large, no sting-cells, head large, cowl-shaped, no tentacles, rhino- phores much foliated, no radula. Genera: Tethys, Melibe. The° cerata of Tethys, which are capable of independent movement 1'This family has also been classified with the Bulloidea and with the Aplysioidea, XV NUDIBRANCHIATA 433 when severed, have been described as parasitic worms. Tethys feeds on molluscs and Crustacea. Fam. 3. Lomanotidae. — Body slug-like, dorsum prominent, undulating or lobed, with one row of small cerata, no tentacles, rhinophores much foliated, radula with uncinated dentate laterals. Single genus, Lomanotus. Fam. 4. Dotonidae. — Body slug-like, small, two rows of cerata, each ceras surrounded by a ring of tubercles, rhinophores simple, radula uniseriate. Single genus, Doto. Fam. 5. Dendronotidae.— Body slug-like, somewhat com- pressed, two rows of arborescent cerata, no tentacles, frontal margin with arborescent papillae, rhinophores arborescent, radula multiseriate. Genera: Campaspe, Dendronotus. Fam. 6. Bornellidae.— Two rows of dorsal papillae, with branchiform appendages at the base, rhinophores foliate, radula multiseriate. Single genus, Bornella. | Fam. 7. Scyllaeidae.— Body oblong, compressed, two large foliated cerata with branchial appendages on the inner side, no tentacles, rhinophores large, radula multiseriate. Single genus, Scyllaea. Fam. 8. Phyllirrhoidae.— Body much compressed, with bovine head and neck, tail tapering, no tentacles, rhinophores simple, teeth few, no marginals. Single genus, Phyllirrhoe. Fam. 9. Pleurophyllidiidae.— Body elongate-oval, snout broad, covered by an arched shield with lateral angles prolonged, branchiae consisting of two rows of lamellae placed between the notaeum and the foot, no tentacles, rhinophores short, hidden, radula multiseriate. Single genus, Plewrophyllidia. Fam. 10. Plewroleuridae. — Animal resembling Pleurophyl- lidia, but without the branchial lamellae. Single genus, Pleu- roleura. Fam. 11. Tritoniidae.— Body long, two rows of unequal arborescent cerata, rhinophores with ramose appendages, liver not prolonged into the cerata. Genera: Tritonza, Marionia. SECTION 2. HOLOHEPATICA. — Cerata medio-dorsal, retractile or not, usually paucifoliate, liver never ramified, usually no jaws. Fam. 1. Dorididae. — Branchia consisting of a circle or semi- circle of pinnate leaves united at the base, surrounding the anus, almost always retractile into a cavity, rhinophores foliate, no - suctorial proboscis, radula multiseriate. Genera: Bathydoris, VOL. III 2F 434. NUDIBRANCHIATA CHAP. Hexabranchus, Archidoris (Fig. 289), Discodoris, Diaulula, Cadlina, Centrodoris, Platydoris, Chro- Th. (ie Bi aN , 7 modoris, Miamira, with many sub- genera. Fam. 2. Doriopsidae.— Branchia and rhinophores as in Dorididae, oral aper- ture pore-shaped, suctorial, no radula. Single genus, Doriopsis. ag) Fam. 38. Phyllidiidae. — Body oval, depressed, leathery, a ring of branchial CAO lamellae, only interrupted by the head Cet ~ér and genital papilla, under the pallial ye edge, oral aperture pore-shaped, suc- Fie. 289.— Doris (Archidoris) torial, no radula. Genera: Phyllidia, tuberculata L., Britain: a, . : . anus: br, branchiag su. “7Yerta. Bergh unites this and the rounding the anus; m, male preceding family in the group Porosto- eee rh,rh, thinophores. j»q¢q which, with Fam. 1, form the group Dorididae eryptobranchiatae. Fam. 4. Polyceridae. — Body slug-like, branchiae not retrac- tile, usually surrounding the anus, rhinophores foliate, tentacles simple, radula variable, central tooth generally wanting. Genera: Notodoris, Triopella, Aegires, Triopa, Issa, Triopha, Crimora, Theca- cera, Polycerella, Palio, Polycera, Ohola, Trevelyana, Nembrotha, Huplocamus, Plocamopherus, Kalinga. Fam. 5. Goniodoridae. — Body oval, depressed, branchia mul- tifolate, usually disposed in shape of a horse-shoe, rhinophores foliate, retractile or not, mouth with a large suctorial proboscis, radula variable. Genera: Akiodoris, Doridunculus, Acanthodoris, Adalaria, Lamellidoris, Calycidoris, Goniodoris, Idalia, Ancula, Drepania. Fam. 6. Corambidae. — Body otherwise Doris-like, but with two posterior branchiae under the mantle edge, jaws present, no central tooth, about five laterals. Single genus, Corambe (= Hypobranchiaea). Bergh unites this and the two preceding families in the group Dorididae phanerobranchiatae. Sub-order IV. Pteropoda.— The Pteropoda are pelagic animals in which the lateral portions of the foot are modified into fins, which are innervated by the pedal ganglia. Their systematic position has undergone recent revision. It has been the custom to regard them as an Order of equivalent value to the xv . PTEROPODA 435 other four, while some have held them to be a subdivision of Cephalopoda. Modern authorities, chief among whom is Pel- seneer, regard the Pteropoda not as a primitive, but as a derived and recent group. They are “ Gasteropoda in which the adapta- tion to pelagic life has so modified their external characters as to give them an apparent symmetry.” The principal point which relates the Pteropoda to the Gasteropoda is the asymmetry of the visceral organs, intestine, heart, kidney, and genital gland, which results from their development on one side only of the body. ‘Their hermaphro- ditism and the structure of their nervous system relate them to the Euthyneura rather than to the Streptoneura. Resemblances in the organs of circulation and generation approximate them to the Opisthobranchiata rather than to the Pulmonata, while of the two groups of the former, they tend to closer relationship with the Tectibranchiata than with the Nudibranchiata. The two sections of Pteropoda have been considered of distinct origin, the Thecosomata being derived from the Bulloidea, the Gymnosomata from the Aplysioidea.1 Thus the Pteropoda are a group whose true relations are masked by the special conditions of their existence, which have tended towards the development of certain organs, the so-called “ wings” and the shell, which give them an apparent symmetry ; this symmetry disappears on a closer investigation of the internal organs. They are hermaphrodite; the genital gland has a single efferent duct (except in some Cavolinia), a seminal groove lead- ing to the copulatory organ, which in the Thecosomata is on the right side of the head, in the Gymnosomata on the right side of the foot. The genital system resembles that of the Opistho- branchiata and of the “digonoporous”’ Pulmonata. SECTION 1. THEcosomaATA. — Shell or cartilaginoid test al- ways present, fins united by an intermediate lobe, ctenidia as a rule absent, replaced by secondary branchiae, no very distinct head or eyes, one pair of tentacles; cerebral ganglia on the sides of and under the oesophagus; radula with three rather large teeth in a row, generally unicuspid, jaw in two pieces, stomach with horny plates, anus generally on the left side. The Thecosomata feed on Protozoa and the lower Algae ; 1 Tt appears more convenient to treat the whole group together, rather than deal with the two sections separately. 436 PTEROPODA — THECOSOMATA CHAP. they have no proboscis, and the intestine is flexured. The fins are always closely connected with the head, or what answers to it. About 42 species are known, belonging to 8 genera. Fam. 1. Limacinidae. — Fins very large, branchial chamber dorsal, anus on right side; shell spiral, sinistral (ultra-dextral, see p. 249), operculate. Genera: Jimacina, shell helicoid, deeply umbilicated (ZL. helicina swarms in Arctic seas and furnishes food for many Cetacea); -Peraclis, spire turreted, aperture large, elongated, produced anteriorly, no umbilicus ; operculum sinistral, in spite of the shell being ultra-dextral. Fam. 2. Cavoliniidae.— Fins large, branchial chamber ventral, Fic. 290.— Illustrations of Pteropoda Thecosomata: A, Limacina australis Eyd.; B, Cleodora cwspidata Bosc. (shell only); C, Cuvierina columnella Rang; D, Creseis virqguia Rang ; E, Clio balantium Rang ; /, f, fins ; J, liver ; 0, ovary ; sh, shell. (After Souleyet.) shell a non-spiral cone, angular or round, very thin, embryonic portion distinct, or formed of two separate plates. In Cavolinia (= Hyalaea, Fig. 5B, p. 10) the shell consists of two plates, the ventral being convex, with one to three sharp spines at the posterior end, the dorsal flatter, without spines. The aperture is broad, contracted dorso-ventrally. Two long pointed prolongations of the mantle project from the lateral slits of the shell, and probably serve to balance the bulky body when swimming. Fins trilobed at the margin. Cleodora has only rudimentary lateral prolongations, fins bilobed, shell triangular, angles greatly produced, aperture very wide, dorsal side keeled. In Cuvierina the shell is straight, sub-cylindrical, with a median partition, slightly expanding towards the apex, which is truncated in the adult. The principal sub-genera of Clio are Creseis, which has an elongated sub-cylindrical shell, sometimes slightly curved, Xv | PTEROPODA — GYMNOSOMATA 437 smooth or grooved; and Clio proper, in which the shell is long, angular, with a dorsal rib, apex (=embryonic shell) rounded, constricted. Styliola and Hyalocylix also belong to this group. Fam. 3. Cymbuliidae. — Test (which is not homologous with the shell of other Thecosomata) slipper-shaped, cartilaginoid, simply a thickening of the mantle; embryo with a calcareous, spiral, operculate shell. Genera: Cymbulia, Cymbuliopsis, Gleba. Three other families, Hyalithidae, Pterothecidae, and Conu- lariidae, from Palaeozoic strata, are generally added to the The- cosomata. All are fossil only, and it is doubtful whether they are really Molluscan. Pelseneer holds that no true fossil Ptero- poda occur until the lower Tertiaries. SECTION 2. GYMNOSOMATA.— Mantle and shell absent in the adult, fins not connected by a lobe, no branchial chamber, head well developed, with two pairs of tentacles, eyes on the posterior pair; cerebral ganglia above the oesophagus; buccal cavity provided with a pair of protrusible “ hook-sacs,” radula generally with 4 to 12 hooked laterals, central tooth triangular, jaw in one piece, composed of horny plates, no horny plates in stomach, anus on the right side. The Gymnosomata are carnivorous, feeding on Thecosomata and other pelagic animals, being provided for this purpose with a tormidable buccal armature of hook-sacs and suckers. The intestine, as usual in carnivorous groups, passes straight from the stomach to the anus; the fins are not attached to the head, but to the anterior part of the body. The larva has a straight shell, which disappears in the adult. About 21 species are known, belonging to 7 genera. ! Fam. 1. Pneumodermatidae.— Animal fusiform, fins rather small, head prominent, anterior part of buccal cavity protrusible, with suckers on the ventral side, hook-sacs well marked; branchia on right side, skin soft, pigmented. Genera: Dezio- branchaea, no posterior gill, hook-sacs short; Spongiobranchaea, posterior gill circular; Pnewmoderma, gill tetraradiate, hook- sacs long. Fam. 2. Clionopsidae. — Body barrel-shaped, proboscis three times the length of the body, no buccal appendages ; hook-sacs short, no lateral gill, posterior gill tetraradiate, skin not pig- mented. Clionopsis is the single genus. Fam. 3. Notobranchaeidae.— Body ovate, buccal appendages 438 PTEROPODA — GYMNOSOMATA CHAP. conical, no lateral gill, posterior gill with three radiating crests, skin pigmented. Notobranchaea is the single genus. Fam. 4. Clionidae. — Body long, angulated behind, proboscis short, mouth with two or three pairs of appendages, no jaw, no ills. i Clione limacina is so abundant in Arctic seas as at times to colour the surface for miles. Each of the cephalic appendages has about 60,000 minute pedicellated suckers. Fie. 291.—A, An- terior portion of Pneumoderma; B, Clione lima- cina Phipps; C, Halopsyche Gaudichaudi Soul.; 7, /, fins; h.s, h.s, hook- ‘sacs; /.f, lobe of the foot; s, s, suckers; 0, pos- terior genital orifice: £,° ie tentacles. (After Souleyet.) Fam. 5. Halopsychidae.— Body ovate, thick, rounded behind, no gill or proboscis, fins long, narrow, broadened at the ends, epidermis sub-cartilaginoid. Halopsyche (= Eurybia) has the power of withdrawing its head completely into a sort of pocket, which is closed by an anterior fold of the mantle. There are two long non-retractile buccal appendages. Order IV. Pulmonata Gasteropoda with two pairs of tentacles, visceral loop euthy- neurous, ganglia concentrated round the oesophagus ; breathing air by a pallial cavity formed by the union of the front edge of the mantle with the cervical region, sexes united, shell present or absent, no operculum?! (except in Amphibola). Sub-order I. Basommatophora.— Eyes generally at the base of the tentacles, which are not retractile, male and female genital orifices separate, radula (p. 235) multiseriate, shell always present, external. Fresh water or quasi-marine. 1 An operculum is said to exist in the young forms of Auricula and Parmacella. xv PULMONATA — BASOMMATOPHORA 439 Fam. 1. Auriculidae. —Breathing organ a pulmonary sac or true lung; shell spiral, conoidal, internal partitions usually absorbed, aperture more or less strongly toothed. Jurassic ; Genera: Auricula, Carychium, Scarabus, Alexia, Tralia, Pleco- trema, Cassidula, Melampus, Leuconia, Pedipes (Fig. 292). Fam. 2. Otinidae.— Shell auriform, spire very short. Genera: Otina, Camptonyx. — Recent only. Fam. 3. Amphibolidae.—A E eay payee night side of Fic. 292. Examples of the Auriculidae : neck, eyes almost pedunculate, a, Auricula Judae Lam., Borneo; B, shell turbinate, rudely soulpt- grgjtbus Zeton! Bln. Ties ured, operculate.—Recent. land; D, Melampus castaneus Miiblf., Genus, Amphibola (Fig. 293) : s Pacific ; E, Pedipes quadridens Pfr., A amaica. subg. Ampullarina. | Fam. 4. Limnaetdae.— Pulmonary sac protected by an exter- nal lobe; shell variable, fragile. Jurassic G.) Ancylinae, shell more or less limpet-shaped. Genera: Ancylus, Gundlachia, Latia. i.) Limnaeinae, shell spiral. Genera: Limnaea, Amphi- peplea, Hrinna, Lantzia, Pompholyx, Choanomphalus (with Carinifex). (iil.) Planorbinae, shell sinistral, spire flattened or elevated. Genera: Planorbis, Isidora (= Bulinus). Fam. 5. Physidae.— Mantle more or less reflected over the shell (radula, Fig. 141c, p. 235); shell sinis- tral, lustrous. Jurassic Genera: Physa, Aplecta. Fam. 6. Chilinidae.— Lobe of pulmonary 7/ sac large, tentacles broad; shell ventricose, I rather solid; columella plicate. Miocene Fic. 293.—Amphibola Single genus, Chilina. i ee Sub-order II. Stylommatophora. — Two pairs of retractile tentacles (except in Janella), eyes at the tip of the upper pair, male and female orifices united (except in Vaginulidae and Onchidiidae), no distinct osphradium. Fam. 1. Testacellidae.— Animal carnivorous, slug-like or spirally coiled, no jaw (whence the name Agnatha, often given 440 PULMONATA — STYLOMMATOPHORA CHAP. to this group), radula with usually few, large, sickle-shaped teeth (p. 232), shell variable, rarely absent, usually external. Cretaceous . Principal genera: Chlamydephorus (shell a | fm simple plate, internal), Apera, Testacella (slug-like, shell ter- minal), WStrebelia, Streptostyla, Glandina, WSalasiella, Petenia, Pseudosubulina, Streptostele, To- mostele, Streptaxis (Fig. 208), Gibbus, Ennea, Daudebardia (Fig. 193), Schizoglossa, Grueste- ria, Aerope, Paryphanta, Rhytida Fic. 294.— A, Ennea (Gibbulina) pa. (Subg. Diplomphalus, Hlaea and langa Fér; A’, young of same; B, Sthenea). eae magnate Fam. 2. sSelenitidae. — Shell internal, external, or absent; jaw present, radula Testacellidan, central tooth present. Tertiary Genera: Selenites, Plu- tonta, Trigonochlamys, Pseudomilax (?), Rathouisia (?). - Fam. 3. Lwmactdae.—Shell present or absent, internal or external, spiral or not, tail often with a mucus pore, jaw (Fig. 107A, p. 211) with projecting rostrum on cutting edge, radula with central tooth tricuspid, laterals bi- or uni-cuspid, marginals aculeate. Eocene Genera: Otoconcha, Urocyclus, Maria- ella (subg. Tennentia), Parmarion, Helicarion, Cystopelta, Aspi- delus, Estria, Vitrinopsis (subg. Vitrinoidea, Parmella), Damay- antia, Nanina (= Ariophanta, including Pachystyla, Rhysota, Hemiplecta, Trochonanina, Euplecta, Orpiella, Xesta, Macro- chlamys, Microcystis, Sitala, Kaliella, Durgella, Austenia, Girasia, Parmacochlea, Africarion, Sesara, Macroceras, and others), Vi- triniconus, Parmacella, Limax (subg. Amalia and many sections), . Vitrina (subg. Vitrinozonites, Velifera), Zonites (subg. Stenopus, Moreletia, Mesomphiz, Hyalinia, Gastrodonta, Pristiloma, Poe- cilozomites, Thyrophorella). Fam. 4. Philomycidae.—Shell absent, jaw limacidan, radula helicidan, shield covering all the body. Single genus, Philo- mycus (= Tebennophorus), with subg. Pallifera. Fam. 5. Helicidae.—Shell present or absent, internal or ex- ternal; jaw of various types, radula with central tooth tricuspid, equal in size to the first laterals, laterals bi- or tri-cuspid, margi- nals smaller, cusped. Eocene Principal genera: Oopelta (no shell), Avion (shell absent or formed of calcareous granules), XV PULMONATA — STYLOMMATOPHORA AAI Ariolimax, Geomalacus, Anadenus (subg. Prophysaon), Hem- phillia, Cryptostracon, Binneya, Helix (see below), Cochlostyla, Bulimus (subg. Borus, Orphnus, Dryptus, Strophochilus, Pachy- otus, and possibly Caryodes, Leucotaenia, Liparus, Livinhacea, Pachnodus, Rachis, Atopocochlis, Cerastus, Clavator belong here, or with Buliminus), Berendtia, Rhodea. Pilsbry proposes! to group Helix as follows: A. Eggs or young very large at birth: (1) Macroén, incl. Acavus, Pyrochilus (=Phania), Stylo- donta, Helicophanta. B. Eggs or young smaller or minute at birth : (2) Belogona.— Female genital system with dart sac and~ mucus gland. Helix [restricted] (with sections Arionta, Campylaea, Chilotrema, Pomatia, Macularia, Tachea, Iberus, Lep- taxis, Eulota, Fruticicola, Xerophila; Dorcasia, Acusta, Plectotropis, Aegista, Cathaica, Satsuma, Euhadra ; Lysinoe), Gonostoma, Leucochroa, Allognathus, Cochlostyla, Polymita, Hemitrochus (with sections Plagieptycha, Dialeuca, Coryda, Jeanerettia), Ee Acan- thinula, Vallonia. (3) Teleophalla.— Female system without accessories, male with flagellum 7 and appendix on penis; no epiphallus. ric. 295.—Example of the Sagida, Clysticnpsis Baas Bie (4) Epiphallophora. — Female Sys- Fisch., Madagascar, show- tem without acessories, male with ing large embryonic shell. epiphallus on penis; no appendix. = Caracolus (with sections Lucerna, Dentellaria, Isomeria, Laby- rinthus, Eurycratera, Parthena, Polydontes, Theliodomus, Cepo- lis), Camaena (incl. Phoenicobius), Obba, Chloritis Gncl. Hadra), Papuina, Planispira (subg. Cristigibba). (5) Haplogona. — Allaccessory organs absent, jaw soldered into one piece. Polygyra (incl. Daedalochila, Triodopsis, Meso- don, Stenotrema), Endodonta (incl. Libera, Charopa, Gerontia, Therasia, and others), Patula, Trochomorpha, Anoglypta. (6) Polyplacognatha. — All accessory organs absent, jaw composed of 16-24 separate plates. Punctum, Laoma. 1 Proc. Ac. Philad. 1892, p. 390. 442 PULMONATA — STYLOMMATOPHORA CHAP, Genera of doubtful position: Strobilops, Ampelita, Pedino- gyra, Polygyratia, Macrocyclis, Solaropsis. . Fam. 6. Orthalicidae.— Radula, p. 283. Shell external, large, bulimoid. Single genus, Orthalicus ; subg. Liguus, Por- phyrobaphe, Corona. Fam. 7. Bulimulidae. — Radula, p. 238; jaw, p. 211; shell usually external. Genera: Bulimulus Gnel. Plecochilus, Goni- ostomus, Drymaeus, Lnostracus, Otostomus, Navicula, Scutalus, Peronaeus, Eurytus, Hudioptus, Plectostylus, Me- sembrinus, Mormus, etc.; Thawmastus, Nesiotis), Placostylus Gnel. Charis), Amphidromus, Partula, Calycia (?), Peltella (animal limaciform, shell inter- nal), Pellicula, Amphibulimus (incl. Stmpulopsis). Fam. 8. Cylindrellidae. — Radula, p. 288; shell many whorled, long turriculate, last whorl — often detached, apex often truncated (Fig. 169, Fie. 296.—Odon- p. 260). Eocene Genera: Cylindrella oe te as (with sections Callonia, Thaumasia), Leia, tagruelinus Moric, 8. Macroceramus, Pineria. ier Fam. 9. Pupidae.—Radula, p. 233; shell external, spire usually long, aperture often narrowed, more or less toothed, often with internal lamellae. Carboniferous , Genera: Anostoma (Fig. 154, p. 248), Hypselostoma (Fig. 2024, p. 302); Anastomopsis (Cretaceous), Lychnus (Cretaceous ), Boysia, Odontostomus Gnel. Tomigerus), Buliminus (incl. Petraeus, Napaeus, Zebrina, Mastus, Chondrula, ina, and perhaps Rachis, Pachnodus, Hapalus, and others), Pupa (nel. Torquilla, Pupilla, Sphyradium, Leucochila, etc.), Zospeum, Vertigo, Megaspira, Strophia, Holospira, Hucalodium Cinel. Coelocentrum), Coeliaxis, Perrieria, Balea; fiillya (Kocene), Clausilia (with many sub- A genera), Rhodina (?). Fra. 297. — A, Clau- Fam. 10. Stenogyridae.— Radula, p. 284; _ silia crassicosta Ben., Sicily; B, shell long, spiral, shining, more or less trans- — Gasitia inaca- lucid, apex blunt, sometimes decollated. Eo- — rana Zieg., Dal- cen é ‘a: Ste tod subs. R ca, matia; B’, clau- vene enera: Stenogyra (subg. Rumina, sium of same. Oheliscus, Opeas, Melaniella, Spiraxis, Leptinaria, Nothus, Subulina, Glessula), Ferussacia (subg. Cionclla, Azeca), Caecilianella (subg. Greostilbia). Achatina (shell large, ventri- XV PULMONATA — STYLOMMATOPHORA 443 cose, columella strongly truncate), with the sub-genera Perideris, Limicolaria, Columna, Pseudachatina, Homorus, probably belongs to a distinct family. Fam. 11. Achatinellidae.— Radula, p. 234; shell small, buli- moid, indifferently dextral or sinistral. Genera: Achatinella (subg. Aurtculella, Amastra, Carelia), Tornatellina. Fam. 12. Succineidae. — Radula, p. 234; lower pair of ten- tacles wanting or small; shell internal or external, thin, spiral or not, last whorl large. Eocene Genera: Succinea, Homalonyx, Hyalimaz, (2) Lnthotis, ?) Catinella. Fam. 18. Janellidae.— Radula, p. 234; animal slug-like, no lower tentacles, shell an internal plate. Single genus, Janella (=Athoracophorus), with subg. Aneitea. Fam. 14. Vaginulidae. — Radula, p. \j 234; animal slug-like, covered with a WW coriaceous mantle, lower tentacles bifid, | genital orifices widely separated, male behind the lower right tentacle, female on inferior median part of right side, anus and pulmonary orifice nearly terminal; shell absent. Single genus, Vaginula pe (= Veronieella). Fam. 15. Onchidiidae. — Body oval, mantle thick, often warty, sometimes set with “eyes” (p. 187), two tentacles, genital orifices widely separate, anus and pulmonary orifice as in Vaginula; no shell. Genera: Peronia, Onchidiwm, Onchi- diella. The family appears to be an instance of Pulmonata reverting to marine habits of life. CHAPTER XVI CLASSES SCAPHOPODA AND PELECYPODA CLASS SCAPHOPODA HEAD rudimentary, mantle edges ventrally concrescent, Fic. 299. — Anatomy of Dentalium: a, anterior aperture of mantle; /, foot; g, genital gland; k, kidney; J, liver. (After Lacaze - Du- thiers.) forming a tube opening before and behind, and covered with a shell of the same shape; sexes separate. The Scaphopoda form a small but very distinct class, whose organisation is decidedly of a low type. The body is usually slightly curved, the concave side being the dorsal ; muscles near the posterior end attach the body to the shell. The foot, which can be protruded from the anterior or wider aper- ture, is rather long, pointed, and has some- times two lateral lobes (Dentalium), some- times a terminal retractile disc (Siphonoden- taliwm), sometimes a retractile disc with a central tentacle (Pulsellum). The cephalic region, as in Pelecypoda, is covered by the mantle. The mouth is situated on a kind of projection of the pharynx; the buccal mass, containing the radula (p. 286), is at the base of the foot, and the intestine branches forward from the front part of the stomach. The liver (Fig. 299) is paired, and consists of a number of symmetrical, radiating coeca. There are no eyes, but on each side of the mouth are small bunches of exsertile filaments (captacula), which appear to act as 444 CHAP. XVI _ . SCAPHOPODA 445 tactile organs for the seizing of food. There is no special respir- ing apparatus, heart or arterial system, breathing being conducted by the walls of the mantle. The nervous system has already been described (p. 205). Two kidneys open on either side of the anus. The genital gland is large, occupying nearly all the posterior part of the body, the sexual products being emitted through the right kidney. The veliger has already been figured (p. 181, Fig. 44). The embryonic shell is formed of two calcareous laminae, which sub- sequently unite to form the tube. With regard to their general relationships, the Scaphopoda resemble the Gasteropoda in their univalve shell, and in the possession of a radula; while the pointed foot, the non-lobed velum in the veliger, the generative system, the bilateral sym- metry of the organs generally, and the absence of any definite head, eyes, or tentacles, are points which approximate them to the Pelecypoda. The Scaphopoda are known from Devonian strata to the present time. They are found at a depth of a few fathoms to very deep water. The only three genera are Dentalium, Siphono- dentalium (subg. Cadulus), and Pulsellum, which differ in the structure of the foot, as described above. CLASS PELECYPODA Cephalic region rudimentary,. mantle consisting of two sym- metrical right and left lobes, covering the body and secreting a bivalve shell hinged at the dorsal margin; no radula, sexes usually separate. Reference has already been made to the reproductive system (p. 145), breathing organs (p. 164 f.), mantle (p. 172), nervous system (p. 205), digestive system (p. 287 f.), and nomen- clature of the various parts of the shell (p. 269 f.). - The shape of the shell, in many Pelecypoda, involving as it does the position, size, and number of the adductor muscles, is probably due to mechanical causes, depending on the habits and manner of life of the individual genus. Thus in a typical dimyarian or two-muscled bivalve, e.g. Mya (Fig. 800, A), the adductor muscles lie well towards each end of the long axis of the shell, with the hinge about midway between them. In this position they are best placed for effectually closing the valves, 4 46 PELECYPODA CHAP, and since they are nearly equidistant from the axis of motion, 7.e. from the hinge, they do an equal amount of work, and are about equal in size. But in a form like Modiola, where the growth of the shell is irregular in relation to the hinge-line, the anterior muscle is brought nearer and nearer to the umbones, where its power to do work, and therefore its size, becomes less and less. But the work to be done remains the same, and the posterior muscle has to do it nearly all; hence it moves farther and farther away from the hinge-line, and at the same time gains in size. In shells like Ostrea, Pecten, and Vulsella, the anterior muscle, having drawn into line with the hinge and the posterior muscle, becomes atrophied, while the posterior muscle, having double work to do, has doubled its size.1 The development of the foot, again, largely depends upon Fic. 300. — Illustrating changes in the position and size of the adductor muscles accord- ing to the shape of the shell: A, Mya; B, Modiola; C, Vulsella. The upper dotted line shows the hinge-line, the lower connects the two muscles. habits of life. It is well developed in burrowing forms, while in sessile genera (Ostrea, Chama, Spondylus) it becomes unnecessary and aborts. Even in Pecten, which does not become sessile, but has ceased to use the foot as an organ of progression, a similar result follows. Forms which burrow deeply often “gape” widely, sometimes at one end only, sometimes at both. Venus, Donaz, Tellina, Mactra, which are shallow burrowers, do not gape; Solen, Lutraria,and to a less degree Mya, burrow deeply and gape widely. In order to burrow deeply the foot must be highly developed, and the larger it becomes, the more will it tend to keep the valves apart at the place where it is habitually protruded. Burrowing species always remain in communication with the surface by means of their siphons, the constant extension of which tends to keep the valves apart at the end opposite to the foot. Burrowing * Compare Jackson, Amer. Nat. xxv. p. 11 f. XVI PELECYPODA — PROTOBRANCHIATA 447 species, again, tend to burrow in such a way as to descend most easily, and not be impeded by their own shells; in other words, they act as a wedge, and descend with their narrowest part fore- most. But the burrowing organ, the foot, has to follow suit, and gradually draws round to the narrowest part of the shell, so that the habitual deep burrower, such as Lutraria, lies with its long axis exactly at right angles to the surface, its siphons protruding from, and keeping open, the uppermost or posterior margin of the shell, and the foot producing the same effect upon the lower or anterior margin. The deeper the burrower, the more elon- gated does the shell become, until, through forms like Pholas and Saxicava, we arrive at Solen, the most highly specialised burrower of all, in which the breadth of the shell is equal throughout, and no obstructive curve exists to impede its rapid ascent or descent. The Pelecypoda have been classified in various ways; by the completeness or sinuation of the pallial line, depending on the absence or presence of siphons, by the number of adductor mus- cles, by the character of the hinge-teeth, and by the number of the branchiae. For various reasons, none of these methods have proved entirely satisfactory. That adopted here was suggested by Pelseneer, and depends upon the character of the branchiae them- selves, as suggesting successive stages of development (p. 166f.). Order I. Protobranchiata Branchial filaments not reflected, the two rows inclined at a right angle (more or less), ventral surface of foot more or less — flattened, byssogenous apparatus little developed, a single anterior aorta, kidneys distinct, sexes separate, each genital gland open- ing into the corresponding kidney. Fam. 1. Nuculidae.— Labial palps very large, rows of bran- chial filaments at right angles to one another, mantle edges open, siphons contracted, foot disc-shaped, elongated; shell equivalve, oval, or produced, interior generally nacreous, hinge with numer- ous saw-like teeth. Silurian Principal genera: Wucula (heart dorsal to the rectum); Palaeoneilo (Devonian), (?) Sa- repta, Leda, Yoldia, Malletia ; Tyndaria (Upper Tertiary), Lyro- desma (Silurian), Actinodonta (Silurian), Babinka (Silurian). Fam. 2. Solenomyidae.— Labial palps united, one row of a J + 448 FILIBRANCHIATA CHAP. branchial filaments pointing dorsally, the other ventrally; mantle edges in great part united postero-ventrally, a single siphonal orifice with two very long tentacles, foot proboscidiform, with a round denticulate disc at the end; shell equivalve, resembling a Solen, with a strong corneous periostracum; no hinge-teeth, liga- ee ment internal. Single genus, Solenomya. (?) Cretaceous ef Order II. Filibranchiata Rows of branchial filaments parallel, pointing ventrally, reflected, and provided with interfilamentary ciliated junctions, foot usually with a well-developed byssogenous apparatus. Sub-order I. Anomiacea. — Heart dorsal to the rectum, a single aorta, foot small, anterior adductor very small; shell ostreiform, no hinge-teeth, fixed by a calcified byssus traversing the right valve (Fig. 173, p. 262). Fam. Anomiidae. — Jurassic Genera: Anomia, Pla- cunanomia; Carolia (Eocene), Placuna ; Hypotrema (Jurassic), Placunopsis (Oolite). Sub-order II. Arcacea. — Mantle edge open, both adductors well developed, heart with two aortae, branchiae free, without interlamellar junctions, no siphons; renal and generative aper- tures distinct. Fam. 1. Arcadae.— Mantle edge with composite eyes; shell round or trapezoidal, solid, often with stout bushy periostracum ; ligament often external, on a special area; hinge with numer- ous lamelliform teeth. Ordovician Principal genera: Arca (incl. Barbatia, Scaphula, and Cucullaea), heart dorsal to rectum; Pectunculus, Glomus, Limopsis ; Trinacria and Nuculina (Tertiary). Fam. 2. Trigoniidae.— Foot large, % hatchet-shaped, with ventral disc; no y byssus, mantle edge with ocelli; shell Sex, sub-trigonal, hinge-teeth few, strong; in- Fra. 301. — Trigonia pecti- terior violet-nacreous. Devonian ae ce Sydney, Genera: Trigonia; Myophoria and Schiez- : odus (Trias), Cyrtonotus (Devonian). Sub-order III. Mytilacea. — Mantle edges fused at one point, anal orifice distinct, anterior terminal adductor small, one aorta, XVI PSEUDOLAMELLIBRANCHIATA 449 branchiae with interfoliary junctions, genital glands penetrating the side of the mantle and opening by the side of the kidneys. Fam. Mytilidae.— Byssus well developed, shell more or less equivalve, oval, broad; hinge-teeth evanescent. Devonian Principal genera: Mytilus, ? Myalina, Septifer, Modiola, Lithodo- mus, Crenella, Dacrydium, Myrina, Idas, Modiolaria, Modiolarea. Order III. Pseudolamellibranchiata Mantle edges entirely open, foot little developed, anterior adductor usually aborted, branchial filaments reflected, with inter- lamellar junctions, which are sometimes vascular; genital glands opening into the kidneys or close to the apertures of the kidneys. Fam. 1. Aviculidae.— Foot long, tongue-shaped, byssogenous apparatus well developed, branchiae concrescent with the mantle, adductor muscle sub-central, at times a small anterior adductor, siphons absent; shell usually inequivalve, dorsal margin straight, often very long, winged, lateral teeth much prolonged; structure of shell cellular, inside prismatic, out- side nacreous. Palaeozoic Principal genera: Fic. 302. — Avicula heteroptera Lam., Aus- Aicul a, includin 9 Melea- ae Nes inequivalve shell and grina, Malleus; Vulsella (no wings or hinge-teeth) ; Perna, including Crenatula, Inoceramus (ligaments in a number of fossettes); Auwcella and Monotis (Palaeozoic and Secondary); Pterinaea and Ambonychia (Palaeo- zoic); Pinna; Aviculopinna (Carboniferous). Fam. 2. Prasinidae.— Shell very small, umbones anterior, incuryed, anterior side depressed, hinge-teeth replaced by denti- form projections of the lunule fitting into corresponding grooves. Recent. Single genus, Prasina. Fam. 3. Ostreidae. — Heart generally ventral to the rectum, branchiae concrescent with the mantle, no byssus; shell inequi- valve, fixed by the left valve, form irregular. Jurassic Genera: Ostrea; Heligmus (QOolite), NMaiadina Comecou, Pernostrea (Jurassic). Fam. 4. Pectinidae.—Byssus usually absent, mantle edge VOL, III 2G 450 PSEUDOLAMELLIBRANCHIATA CHAP. open, duplicated, folded back, with pallial ocelli; branchiae not concrescent with the mantle; shell with unequal “ears” at the umbo, hinge-teeth lamelliform, often ob- scure. Silurian——. Principal genera:.Pedum, Chlamys, Hinnites, Hemipecten, Amussium, Pecten; Aviculopecten (Palaeozoic), Crent- pecten. Fam. 5. Limidae.— Mantle edge as in Pecten, tentaculate; shell sub- equivalve, eared, fixed by a byssus or free. Carboniferous . Gen- era: Lima (Fig. 85, p. 179), Limea. Fam. 6. Spondylidae. — Foot with a peduncular appendage, no byssus, numerous pallial ocelli; shell fixed by right valve, surface often very spinose, two cardinal teeth in each valve. Jurassic Genera: Plicatula, Spondylus; Terquemia (Lias). Fie. 303.— Pecten pallium L., East Indies. 4 Fic. 304. — Spondylus petroselinum Sowb., Mauritius; on a coral. WA LE Fam. 7. Dimyidae.— Shell ostreiform, fixed, hinge with or without symmetrical teeth, two muscular impressions. Single genus, Dimya (Tertiary). — a on XVI EULAMELLIBRANCHIATA — SUBMYTILACEA 451 Order IV. Eulamellibranchiata Mantle edges united at one or more points, branchiae with in- terfilamentary junctions which are always vascular, genital glands not opening into the kidneys, usually two adductor muscles. Sub-order I. Submytilacea.— Mantle edges more or less open, anal orifice distinct, usually no siphons, palhal line usually simple, cardinal and lateral teeth well marked. Fam. 1. Carditidae.— Foot with a byssus or groove, branchiae large, unequal; shell equivalve, solid, radiately grooved, one or two oblique cardinal teeth, one or two laterals. Silurian Principal genera: Venericardia, Cardita, Carditella, Carditopsis, Milneria ; Pleurophorus (Palaeozoic), Anodontopsis (Silurian). Fam. 2. Astartidae.— A short anal siphon, labial palps large ; shell triangular, thick, ligament external, hinge with two or three cardinals in each valve, laterals obscure. ? Devonian Principal genera: Astarte; Pachytypus (Jurassic), Plesiastarte (Eocene), Parastarte, Woodia, Opis (Secondary strata), Proso- coelus (Devonian). Fam. 8. Crassatellidae.— Mantle with anal orifice or open; shell equivalve, thick, subtriangular, ligament in an internal fossette, hinge with two cardinals, laterals produced. Creta- ceous Principal genus, Crassatella. Fam. 4. Cardiniidae.— Shell equivalve, oval or triangular, ligament external, cardinal teeth small, laterals fairly strong. Devonian Oolite. Principal genera: Cardinia, Anthracosia, Carbonicola, Anoplophora. Fam. 5. Cyprinidae. — Anal and branchial orifices complete, papillose, foot thick ; shell variable, equivalve, thick, umbones often spiral, hinge-teeth very variable, ligament external. Jurassic Principal genera: Cyprina; Pygocardia WG (Crag), Veniella (Cretaceous), Venilicardia (Secondary strata), Anisocardia (Jurassic), Isocardia, Libitina, Coralliophaga; Basterotia (Eocene). The families Pachydomidae (Pa- iy laeozoic) and Megalodontidae (Palaeozoic — py. 395.—Zsocardiavulk- - Secondary) are probably related to the Cyp- —_garis Reeve, China. rinidae. Fam. 6. Aetheriidae.— Anal orifice complete, foot absent, 452 EULAMELLIBRANCHIATA — SUBMYTILACEA CHAP. labial palps large ; shell irregular, free or fixed, no hinge-teeth. Fluviatile, recent only. Genera: Aetheria, Miilleria, Bartlettia. Fam. 7. Unionidae. — Foot large and thick, no byssus, anal siphon short, branchial orifice complete or not, siphon present or absent, embryo of certain groups passing through a glochidiwm stage (p. 146); shell equivalve, sometimes very thick, nacreous within, hinge variable. Fluviatile. Jurassic Principal genera: Unio (subg. Arconaia), Monocondylaea, Pseudodon, Ano- donta, Solenaia, Mycetopus, Mutela, Spatha, Hyria, Castalia, Leila. Fam. 8. Dreissensiidae.—Both siphons prominent, foot tongue- shaped, byssiferous ; shell mytiliform, with small internal septum. Genera: Dreissensia; Dreissensiomya (Tertiary). The common Dreissensia polymorpha Pall. was distributed over large parts of Europe in later Tertiary times. From unknown causes it died out, and has during the past two hundred years been regaining its position, migrating N. and W. from its original habitat, the Caspian, by the Volga and its Oka confluent. Fam. 9. Modiolopsidae.—Shell mytiliform, ligament exterior, hinge-teeth small, rather numerous. Palaeozoic Principal genera: Modiolopsis, Cyrtodonta, Mytilops, Ptychodesma. Fam. 10. Lucinedae. — Anal orifice sometimes with a siphon, branchial orifice complete or not, sometimes a single branchia; foot very long, vermiform, no byssus, anterior adductor long; shell rounded, equivalve, blanched, hinge with two cardinals and two laterals in each valve, sometimes toothless, ligament more or less internal. Silurian Principal genera: Lwueina, Corbis, Avinus, Diplodonta, Montacuta. Fam. 11. Ungulinidae.— Anal orifice complete, foot vermi- form, no byssus, two branchiae ; shell equivalve, subcircular, hinge- teeth variable, no laterals, adductor impressions long, continuing the pallial line. Tertiary Single genus, Ungulina. Fam. 12. Unicardiidae.— Shell equivalve, round or oval, cardinal shelf large, a single cardinal in each valve, ligament external. Carboniferous — Cretaceous. Genera: Unicardium, Scaldia, Pseudedmondia. Fam. 13. Kellyellidae.— Anal siphon prolonged, no marked branchial orifice ; shell very small, oval or round, anterior lateral very strong, under the cardinal. Eocene Genera: Kelly- ella; Allopagus and Lutetia (Tertiary), Turtonia. Fam. 14. Hrycinidae.— Mantle edges with three apertures, XVI EULAMELLIBRANCHIATA — TELLINACEA 453 branchial orifice on the buccal margin, foot long, broadened, with a byssus, animal usually viviparous. Tertiary Genera: Hrycina, Kellia, Pythina, Lasaea, Lepton. Fam. 15. Galeommidae.— Mantle edges more or less re- flected over the shell, apertures and foot as in Erycinidae; shell thin, equilateral, hinge with few teeth or none. Tertiary Genera: Galeomma, Scintilla, Sportella, Chlamydoconcha, Hinds- tella, Ephippodonta (Fig. 32, p. 81). Fam. 16. Cyrenidae.—Siphons short, foot large, no bys- sus; shell equivalve, subtriangular, with periostracum, hinge with two or three cardinals, laterals present; animal hermaphro- dite, viviparous. Fresh or brackish water. Jurassic Gen- era: Cyrena, Corbicula (subg. Batissa, Velorita), Sphaerium (= Cyclas), Pisidium, Galatea, Fischeria. The families Cyrenellidae (single genus, Compras and Rangitidae (single genus, Rangia) are probably to be placed here. Sub-order II. Tellinacea. — Siphons long, separate, foot and labial palps very large, pallial sinus deep, two adductor muscles. Fam. 1. Tellinidae.— External branchial fold directed dorsally, foot with byssogenous slit, but no byssus, branchiae small; shell compressed, equivalve, ligament external, at least two cardinals in each valve, laterals variable. Cretaceous Principal genera: Yellina (with many sections), Gastrana. Fam. 2. Scrobiculartidae. — Animal asin Tellina; shell orbic- ulate or long oval, equi- valve, hinge-teeth weak, ligament in an internal cavity. Tertiary Principal genera: Serobi- cularia, Syndosmya, The- ora, Cumingia, Semele. F'am.3. Donacidae.— External branchial fold directed ventrally ; shell equivalve, subtriangular, solid, smooth, two or three cardinals in each valve, laterals variable, ligament external. Jurassic Genera: Donax, Iphigenia, [sodonta. Fam. 4. Tancrediidae.— Shell donaciform, ligament external, cardinals usually two in each valve, posterior laterals strong. Trias . Genera: Tancredia (Secondary strata), Hemidonaz. Fic. 306. — Tellina rastellum Hanl., East Indies. 454 EULAMELLIBRANCHIATA — VENERACEA - CHAP. Fam. 5. Cardiliidae.—Shell heart-shaped, hinge as in Mactridae, posterior adductor resting on a myophore or shelf. Single genus, Cardilia. Tertiary ; Fam. 6. Mesodesmatidae.— Mantle edges largely united, with three orifices, foot byssiferous or not; shell regular or irregular, usually one cardinal and strong lateral teeth. Tertiary Genera: Mesodesma, Hrvilia. Fam. 7. Mactridae.— External branchial fold directed ven- trally, siphons fused, foot tongue-shaped; shell equivalve, triangular-oval, hinge with ligament in an internal fossette, another portion external, a bifurcated cardinal tooth in the left valve, fitting into a branching tooth in the right valve, laterals present. Jurassic Genera: Nactra, Harvella, Raéta, EHastonia, Heterocardia, Vanganella. Sub-order III. Veneracea. — Branchiae slightly folded, foot compressed, siphons generally short, pallial line variable, two adductor muscles. Fam. 1. Veneridae.—Siphons free or partly united, foot sel- dom byssiferous; shell solid, equivalve, hinge usually with three cardinal teeth, laterals variable. “SS Jurassic . Principal genera: Yi) SS Cytherea, Circe; Grateloupia (Ter- =z, ) tiary), Meroe, Dosinia (= Artemis), —, y} | Cyprimeria, Cyclina, Venus, Clem- : Zz ty entia, Lucinopsis; Thetis (Creta- N SZ cous), Tapes, Venerupis. Fie. 307. — Oythored dione Lam., Peru. faa 2. Retreclid ae aaa perforating rocks; shell oval, slightly gaping behind, two or three cardinals, no laterals, pallial sinus well marked. Recent Genera: Petricola, Naranio. Fam. 3. Glaucomyidae. — Siphons long, united, foot small; shell produced, thin, hinge with three cardinals, no laterals, pallial sinus well marked. Recent Genus, Glaucomya Cnel. Tanysiphon). Sub-order IV. Cardiacea. — Branchiae much folded back, mantle edges with three apertures, foot cylindroidal, more or less produced, siphons present or absent, one or two adductor muscles, pallial line variable. Fam. 1. Cardiidae. —Siphons rather long, foot long, no byssus ; shell equivalve, more or less radiately ribbed, hinge with ee 2 i EULAMELLIBRANCHIATA — CARDIACEA 455 one or two cardinals in each valve, laterals variable, ligament external, two adductors. Brackish water or marine. Devo- nian . Genera: Byssocardium and Inthocardium (Tertiary), Conocardium (Palaeozoic), Cardium (with many sections, including Hemi- cardium), Limnocardium (subg. Di- dacna, Monodacna, Adacna). Fam. 2. Lunulicardiidae. — Shell equivalve, very inequilateral subtri- angular, anterior margin short or trun- cated, with a deep lunule. Single genus, Lunulicardium (Palaeozoic). Fam. 8. Tridacnidae.— Mantle ori- fices widely separated, foot short, bys- Be Sa aeeaa nenee es siferous, no anterior adductor; shell gum) cardissa L., East Indies. equivalve, large, thick, usually gaping in front, one cardinal tooth and one or two posterior laterals in each valve, no pallial sinus. Miocene . Genera: Tridaena, Hippopus. The muscular power of the great 7ridacna is immense. Once caught between their gaping valves, a man’s hand or foot can scarcely be withdrawn. Two valves of TZ. gigas in the British Museum weigh respectively 154 and 156 lbs. Fam. 4. Chamidae.— Mantle orifices widely separated, foot short, no byssus, both adductors present, ovary invading the mantle lobes; shell fixed, irregu- larly inequivalve, umbones spiral, ligament external, cardinal teeth often a mere ridge, anterior lateral strong, nearly central, no pallial sinus. Jurassic . Genera: Chama; Diceras (Jurassic), at- tached by one umbo, umbones oes very prominent, teeth strong; Fic. 309.— A, Requienia ammonea Heterodiceras (Jurassic ), Re- Goldf., Neocomian, x 3; B, Hippu- quienia (Cretaceous), left valve ee et oat Aad widely spiral, attached by the of fixture. (From Zittel.) umbo, right valve small, fitting on the other as an operculum, teeth obsolete; Toucasia, Apricardia, Matheronia (all Secondary strata). 456 EULAMELLIBRANCHIATA — MYACEA CHAP. The four succeeding families require special study in a work on Palaeontology. Fam. 5. Monopleuridae. — Shell very inequivalve, left valve operculiform, right conical or spiral, fixed at the apex, ligament prolonged in external grooves. Cretaceous Genera: Monopleura, Valletia. Fam. 6. Caprinidae. — Shell very inequivalve, thick, free or fixed by apex of right valve, which is spiral or conical, left valve spiral or not, often perforated by radial canals from the umbo to the free margin. Neocomian and Cretaceous Principal genera: Plagioptychus, Caprina, Ichthyosarcolites, Caprotina, Polyconites. Fam. 7. Hippuritidae (= Rudistae).—Shell very inequivalve, externally as in Caprinidae, umbo central in left valve, no liga- ment proper, left valve with strong hinge-teeth and grooves, two adductor impressions on prominent myophores, shell structure of the two valves differing: Cretaceous only. Single genus, Mippurites (Fig. 809, B). Fam. 8. Radiolitidae.—Shell inversely conical, biconical, or cylindrical, general aspect of Hippurites, umbo of left valve central or lateral, right valve with a thick outer layer, often foliaceous, umbonal cavity partitioned off by laminae: Creta- ceous only. Genera: Radiolites, Biradiolites. Sub-order V. Myacea.— Branchiae much folded back, man- tle edges usually with three openings, foot compressed, siphons large, united or not, two adductor muscles, pallial line variable. Fam. 1. Psammobiidae.— Siphons long, not united, foot large, not byssiferous; shell equivalve, long, oval, slightly gaping at the ends, ligament external, prominent, two cardinal teeth in each valve, no laterals, a deep pallial sinus. Jurassic ; Genera: Psammobia, WSolenotellina, Sanguinolaria, Asaphis, Hlizia, Quenstedtia (Jurassic). Fam. 2. Myidae.— Pedal orifice small, siphons long, united in great part; shell inequivalve, gaping at one or both ends, periostracum more or less extensive, ligament internal, resting on a prominent shelf; hinge-teeth variable. Cretaceous Genera: Mya, Tugonia, Sphenia, Corbula, Lutraria (for which latter some propose a separate family). FAm. 8. Solenidae.— Foot long, powerful, more or less cylin- drical, no byssus, siphons usually short, united or not, branchiae XVI - EULAMELLIBRANCHIATA — PHOLADACEA 457 narrow ; shell equivalve, long and narrow, gaping at both ends, with periostracum, umbones flattened, ligament external, hinge- teeth variable. ? Devonian Genera: Solecurtus, Pharella, Pharus, Cultellus, Siliqua, Ensis, Solen, Orthonota (?), Palaeosolen (?). Fam. 4. Glycimeridae.— Pedal orifice very narrow, siphons long, united in great part, often covered with periostracum ; ‘shell more or less equivalve, gaping at both ends, hinge toothless or with two weak cardinals, ligament external; animal free or perforating. Cretaceous Genera: Glycimeris, Saxicava, Cyrtodaria. Fam. 5. Gastrochaenidae. — Foot small, cylindrical, no byssus, branchiae narrow, siphons long; shell perforating or cemented to a shelly tube, gaping widely on the anterior and ventral sides, no hinge-teeth, a deep pallial sinus. Cre- taceous . Genera: Gastrochaena, Fis- tulana (tube with a median diaphragm, perforated by the siphons). Sub-order VI. Pholadacea. — Man- tle edges largely closed, siphons long, united, foot short, truncated, disc-shaped, ligament absent, two adductor muscles; animal perforating. Fam. 1. Pholadidae. — Organs con- tained within the valves, ctenidia pro- longed into the branchial siphon, shell more or less gaping, thin, dorsal margin in part reflected over the umbones, one or more dorsal accessory pieces, no hinge- p,, 319. Teredo navalis teeth, an interior apophysis proceeding L.: V, valves of shell; from the umbonal cavity. Jurassic Genera: Pholas, Talona, Pholadidea (posterior extremity of the valves prolonged by a corneous appendage, a passage to the long tube of Teredo), Jowannetia, Xylophaga, Martesia; Teredina (Eocene). Fam. 2. Teredinidae. — Animal vermiform, ctenidia mainly siphons. (After Mobius.) T, tube; P, pallets; SS, >» 458 EULAMELLIBRANCHIATA — ANATINACEA CHAP. within the branchial siphon, siphons very long, with two calca- reous appendages (“ pallets’) near the anterior end, shell very small, continued into a long calcareous tube, valves deeply notched, internal apophysis as in Pholadidae. Lias : Single genus, Zeredo (Fig. 310). Sub-order VII. Anatinacea. — External branchial fold directed dorsally, not reflected, sexes united, ovaries and testes with separate orifices, mantle edges largely united, byssus usually absent, two adductor muscles, pallial line variable, shell usually nacreous within. Fam. 1. Pandoridae.—Siphons short, largely united, foot tongue-shaped; shell free or fixed, inequivalve, semilunar, or subtriangular, ligament often with calcareous ossicle, pallial line complete or with slight sinus. Cretaceous . Genera: Pan- dora, Myodora, Myochama. Fam. 2. Chamostreidae.—Shell fixed, Chama-like, thick, umbones jg Spiral, ligament with ossicle. Hii Single genus, Chamostrea. Wy Fam. 8. Verticordiidae. — Siphons not prolonged; shell heart- shaped, umbones prominent, spiral, ligament with an ossicle, pallial Fic. 311.—Myochama Stutchburyt line complete. Miocene . Gen- A. Ad., attached to Circe unda- tina Lam., Moreton Bay. onsiella. Fam. 4. Lyonsiidae. — Foot short, byssiferous, siphons short, separate, shell inequivalve, hinge-teeth usually absent, ligament and ossicle in an internal groove. Hocene Single genus, Lyonsia. Fam. 5. Ceromyidae.—Shell inequivalve, large, heart or wedge shaped, hinge toothless, ligament internal in one valve, external in the other. Secondary strata . Genera: Ceromya, Gresslya. Fam. 6. Arcomyidae.—Shell equivalve, thin, surface finely granulated, hinge toothless, cardinal edge dentiform, ligament external. Secondary and Tertiary strata Genera: Arco- mya, Goniomya, Pleuromya, Machomya. Fam. 7. S SK ie RX ry J Ur a S Ss . = % 1The results of the investigations of King (Ann. Mag. Nat. Hist., 4th ser., vol. xii., 1873) and of Brooks (Chesapeake Zool. Laboratory, Scientijic Results, p. 35, 1879), and the simple nomenclature of these authors are here followed in preference to those of others, owing to the difference of opinion amongst anato- mists of the functions and homologies of the muscles. ‘The lateral muscles enable the valves to move backwards and forwards on each other; the centrals close the shell; the umbonals open it; and the transmedians allow a sliding sideways movement of one valve across the other (see also p. 477). * Davidson and. King, Quart. Jour. Geol. Soc., xxx. (1874), p. 124. XVIII. ECARDINES: INTERNAL CHARACTERS 495 of the Trimerellidae. A pair of ‘transverse’”’ scars (t) occurs in each valve between the “terminals” and the antero-lateral edge of the “platform” (7). ‘ Cardinal” (v), “sub-cardinal ” (w), and ‘“‘umbo-lateral” (x) scars also occur. The median impression which covers the “platform” (7) consists of a central, lateral, and usually an anterior pair of scars; and the impressions of the genital organs, according to Davidson and King, lie medianly posterior to the “platform.” The “platform” Fic. 323. — Trimerella. (After Davidson and King.) A, Inner surface of pedicle-valve or ventral valve: a, pseudo-deltidium; 6, deltidial slope; c, deltidial ridges; d, areal borders; e, cardinal callosities; f, cardinal facet; g, lozenge; 7, umbonal chambers separated by cardinal buttress; 7, platform; &, platform vaults; /, median plate; m, median scars; n, anterior scars; 0, lateral scars; p, post-median scars; qg, crown crescent; 7, side or lateral crescent; s, end or terminal crescent; ¢, trans- verse scars; u, archlet (vascular sinuses); w, sub-cardinal scars; x, umbo-lateral scars. B, Brachial or dorsal valve: e, cardinal sockets; j, platform; k, platform vaults; 7, median plate; m, median scars; », anterior scars; qg, crown crescent ; 7, side or lateral crescent; s, end or terminal crescent; ¢, transverse scars; u, archlet (vascular sinuses); v, cardinal scars; w, sub-cardinal scars. itself is a more or less conspicuous central calcareous elevated area occurring in each valve, but most developed in the dorsal ; in some cases it is double-chambered with tubular cavities (‘platform vaults,” Fig. 823, A, B,#), in others it is more or less solid. It appears to have originated through a posterior shifting of the central muscular bands, that they might be inserted behind the liver; at the same time a deposition of shelly material, to form fulcra to work the heavy valves, took place at these points. The tunnelling-out of the platform was probably due 496 FOSSIL BRACHIOPODA CHAP. to the continual pressure of the lobes of the ver. The division of ‘the umbonal cavity into definite chambers in Monomerella, and to a less extent in other members of this family, appears, according to Davidson and King, to have been caused by pressure of the ovarian lobes. In connexion with the foregoing remarks on the development of the “ platform,” it may be mentioned that the paths along which the muscle-bands move, as the shell of Brachiopods in- creases in size, are marked by elongated scars, and often by shelly deposits; and when the members of a muscle-pair come into juxtaposition these shelly deposits (which act as fulcra for the muscles) combine, and by the growth of the shell form a septum, as in the case of the median septum of Lingulepis. The Obvolidae show some important features in the internal impressions. Obolella crassa (Hall) may be taken as a well- known type of the family. In this species a pair of small scars, one on each side of the pedicle-groove, lies close under the hinge line in the ventral valve. There is also a well-marked scar for the insertion of the pedicle-muscle at the end of the pedicle-groove. A pair of much elongated lateral impressions extending forward from the “cardinals” may be homologous with the “laterals” of Lingula; and the two small central scars between them may be compared with the “centrals” of Lingula which are in a somewhat similar position. In the dorsal valve of O. crassa a pair of “cardinals” is found, and on each side of a low median rounded ridge are two small “central” scars. Indistinct “lateral” scars arise close to or in the central area, and diverge anteriorly. Sometimes a great concentration of muscle-scars occurs round the foramen in the ventral valve, as in Stphonotreta. As regards the minute structure and composition of the shell in the Ecardines, we find that the Zingulidae and Discinidae have their shell composed of alternating layers of phosphate of lime and a corneous substance; the former layers are pierced by microscopic canals. The Craniidae have calcareous shells traversed by tubules, which divide into many fine branches near the external surface; a thin periostracum covers the exterior. The Trimerellidae have heavy thick calcareous shells, for which they required the previously-described elaborate arrangement of muscles to open and shut them, XVIII TESTICARDINES: EXTERNAL CHARACTERS 497 Il. TESTICARDINES External Characters ‘It is to this division that the great majority of the Brachio- poda belong; and the diversity of form, of ornamentation, and of internal characters is correspondingly greater than in the Kcardines. A transversely or longitudinally oval shape of shell is the commonest; but sometimes it is triangular, as in Rhynchonella (Fig. 327), or bilobed, as in Pygope (= Terebratula diphya). The ventral valve is usually more convex than the dorsal, and the former may be prolonged into a tube by the accelerated growth and infolding of the anterior and lateral margins, producing a very abnormal form (Proboseidella). The external surface of the valves is frequently ornamented with more or less prominent radiating ribs; and fine concentric growth-lines are commonly shown, and may be developed into coarse ridges or wrinkles, particularly in old individuals. The members of the family Productidae are usually furnished with tubular spines, which are sometimes of great length, and served to anchor the free shells in the mud, or were twisted round Crinoid stems and similar objects. In the ventral valve of many genera there is a median sinus, with a corresponding fold in the dorsal valve, and rarely vice versd ; sometimes the fold and sinus are double. The hinge line is either curved or straight, and the valves are articulated by means of a pair of “hinge-teeth” (Fig. 329, ¢) in the ventral valve, which fit into corresponding sockets in the opposite valve. Some genera have the teeth very rudimentary, or have lost them altogether. The teeth are frequently sup- ported by “dental plates,” and the sockets by “socket plates ” (e.g. Conchidium, Figs. 324, 325). A few genera with a long hinge line have the whole of it denticulated (Stropheodonta). In the dorsal valve medianly close under the hinge line is a shelly protuberance —the ‘cardinal process””—to which the diductor muscles are attached. It is sometimes of great length and forked (Stringocephalus, Fig. 326), or tripartite, or even quadripartite ; but in Rhynchonella and some other genera it is rudimentary. VOL, III 2K 498 FOSSIL BRACHIOPODA | CHAP. ‘ A “hinge area” (Fig. 334, ea) is often present on one or both valves, and may be of great size, as in Clitambonites, but in Productus it is wholly absent. In those genera that possess it a triangular fissure —the “‘deltidial fissure” — frequently traverses len : as Fig. 325.—Conchidium galea- tum. Transverse section. d, Dorsal valve; d.s, dorsal septum; s, socket plate; uv, Fig. 324. — Conchidium galea- ventral valve; v.s, ventral tum. Wenlock Limestone. septum; d.p, dental plate. it on both valves; in the dorsal valve the fissure is merely the space between the dental sockets, and may be occupied by the car dinal process (Fig. 334, C) or covered by a shelly plate — the ‘‘chilidium.” In the ventral valve it gives passage to the pedicle, Fic. 326.— Stringocephalus Burtini. (Modified from Woodward.) Devonian. A, Interior of dorsal valve. B, Side view of interior of shell; «, adductor (= occlusor) scars; c, crura; c.p, cardinal process; d.s, dorsal septum; h.p, hinge plate; l, brachial loop; s.p, shelly processes; t.s, dental sockets; v.s, ventral septum. and may be partly or entirely closed by a similar plate (Fig. 334, d) known as the “ pseudo-deltidium,” especially large in Clitambonites, or remain open (Orthis). This pseudo-deltidium is a primitive character, and arises in an early stage of the XVIII TESTICARDINES: INTERNAL CHARACTERS 499 development as a shell-growth on the dorsal side of the animal, becoming attached to the ventral valve subsequently. The pedicle in many genera passes out through a special foramen in the beak of the ventral valve; and its proximal portion is often embraced by a pair of small plates — the deltidial plates or “ del- tidium” — which are formed on lateral extensions of the ven- tral mantle lobe, according to Beecher. These plates lie on each side of the pedicle, or grow round and unite in front of it (Rhynchonella, Fig. 327), or constitute merely its anterior border (Terebratula, Fig. 328). In some cases this foramen becomes closed in old age. The dorsal valve in a few cases has its beak perforated by a Fig. 327.— Rhynchonella : Boueti. (Cornbrash.) Fig. 328. — Terebratula sella. d, Deltidium; f, fora- (Lower Greensand.) d, Del- men. tidium ; 7, foramen. foramen — the “visceral foramen.” This foramen is in no way connected with the pedicle foramen, but points perhaps to the existence in the early Testicardinate genera of an anal aperture. In Athyris concentrica (Devonian) this foramen is connected internally with a cylindrical tube, which extends longitudinally to about one-third the length of the valve. In Centronella the aperture in the cardinal plate is rounded and complete; and in Strophomena and its allies the opening lies between the cardinal processes. If this feature is correctly interpreted, it suggests a retrogression of the group since Palaeozoic times not only in numbers, but in structure; and other evidence points the same way. . Internal Characters The interior of the shell is sometimes more or less divided up by septa. A median septum occurs in one or both valves of many genera as a low ridge or strongly developed partition ( Wald- 500 FOSSIL BRACHIOPODA CHAP. heimia, Fig. 829, ss; and Stringocephalus, Fig. 326, B, v.s). Con- chidium (Fig. 825) has its dental plates of great size, and unit- ing to form a V-shaped chamber or “spondylium,” supported by a median double septum; and by means of these with a pair of septa and the large socket-plates in the dorsal valve the interior of the shell of this genus is divided up into several chambers. The interiors of several other genera are somewhat similarly divided up. In the Carboniferous genus Syringothyris two special plates, situated between the dental plates, are rolled into an incomplete tube, so as to enclose probably the anal extremity of the ali- mentary canal; and in several genera a sub-umbonal “ cardinal Fic. 329. — Waldheimia (Magellania) flavescens. A, Interior of ventral valve: a, adductor scars; v.a, ventral adjustors; d, divaricators; a.d, accessory divaricators ; p, peduncular muscle; dm, deltidium; /, foramen; ¢t, teeth. B, Interior of dorsal valve: d.a, anterior adductor (occlusor) scars; a.p, posterior adductor (occlusor) scars; c.p, cardinal process; cr, crura; d.s, dental sockets; hp, hinge-plate; J, ' brachial loop; ss, septum. (After Davidson.) plate” is present, which is perforated (Athyris) or slit in some cases for the passage of the anal tube. For the support of the fleshy “spiral arms” the calcareous structures forming the “ brachial apparatus” are of two main types —(1) the loop type; (2) the spiral-cone type. In the Strophomenidae no special calcareous support seems to have been usually present (Fig. 884), though in some species of Leptaena spirally-grooved elevated areas supported the fleshy arms; in the Productidae it is probable that the ridges enclosing the “ reni- form impressions ” (Fig. 838, 7) served for a similar purpose. The Terebratulidae show the “loop type” of brachial appa- ratus. In Waldheimia (Fig. 829), which may be taken as an XVIII TESTICARDINES: INTERNAL CHARACTERS 501 example, we notice first in the dorsal valve the “crura” (cr), from which arise the two “descending branches” which run forwards and then are bent back to form the “ascending branches” which are united by the “ transverse band.” In some genera the ‘ascending branches” may be reduced to mere points, and the “transverse band” become a median vertical plate; the “crura,” too, may be fused so as to form a “crural band”; and the “descending branches” may be connected by a cross band — the “jugal band.” In Stringocephalus (Fig. 326, 1, s.p) the loop is furnished on its inner edge with radiating pro- cesses; and in Argiope the loop is simple, not reflected, and fused with marginal septa; while in the Thecididae it is more or less fused with the shell itself, and with the mass of calca- reous spicules secreted by the mantle. The “spiral-cone type” of brachial apparatus is found in the Spiriferidae, Atrypidae, and Koninckinidae, and consists of two spirally-enrolled calcified lamellae, forming two cones with their apices directed laterally GSprrifera, Fig. 330), or towards the interior of the dorsal valve (Atrypa, Fig. 332), or towards each other (Glassia); or forming two flat spirals in the same plane (Koninckinidae). A “jugal band” is generally present, but varies much in posi- tion, and in some genera has complicated posterior gm processes. | The Rhynchonellidae have no loop or spiral cones, but merely a pair of short “ crura.” The principal modifica- tions in the attachments of the muscles in the Zes- ticardines are illustrated by Productus giganteus (Fig. 3383), Leptaena rhomboidalis (Fig. 334), and Waldheimia jflavescens (Fig. 329). In Productus (Fig. 333) we see in the ventral valve a pair of dendritic occlusor, often called adductor, impressions and a pair of large flabellate divaricator impressions. In the dorsal valve the large “cardinal process” served for the attachment of the divaricator, and a low median septum separated the den- Limestone.) Showing brachial spires. 502 FOSSIL BRACHIOPODA CHAP, dritic occlusor scars, which are rarely divisible into anterior and posterior pairs. | . In Leptaena (Fig. 334) the occlusor scars (a) in the ventral Fic. 331.— Atrypa reticu- Fic. 332. — Interior of the same, seen laris. (Wenlock Lime- from the dorsal side, showing stone.) brachial spires. (After Hall.) valve are narrow and median, and are enclosed by a pair of flabelliform divaricator impressions (d.v); in the dorsal valve two pairs of occlusor scars (a.a, p.a) are well marked, and ac- cessory posterior occlusor scars are traceable in some specimens. a A P. SS SY f an l aS \\ AN \ cass 2 INN y | Wp VZaeN | \ IS KS SS oy \ Ue. / \ mel > Fic. 333. — Productus giganteus. (After Woodward.) Carboniferous Limestone. A, Interior of dorsal valve. B, Interior of ventral valve. C, Transverse section of valves. D, Hinge line of A: a, occlusor scars; d, divaricator scars; 7, ‘‘ reni- form impressions’’; ca, cardinal process; h, hinge line; p, brachial prominence; s, cavity for spiral arms; do, dorsal valve; ve, ventral valve. The vascular sinuses (v.s) and genital areas are conspicuous in many species of this and other genera. In Waldheimia (Fig.329) a sub-umbonal “ peduncular muscle ” XVIII TESTICARDINES: INTERNAL CHARACTERS ~ 503 scar (p) in the ventral valve has before it a pair of “accessory divaricator”’ scars (a.d) flanked by a pair of “ ventral adjustor ” (v.a) and a pair of “ divaricator ” impressions (d), between which lie the two occlusor scars (a). In the dorsal valve anterior and posterior pairs of occlusor scars (a.a, a.p) are visible. The minute structure of the calcareous shell of the Testi- cardines is of flattened fibrous prisms inclined at a very acute Fig. 334. — Leptaena rhomboidalis. (Silurian.) A, External view of ventral valve. B, In- terior of ventral valve: a, occlusor scars; d, pseudo-deltidium ; d.v, divaricator scars; c.a, hinge area; ¢, teeth. C, Interior of dorsal valve: a.a, anterior occlusor scars; p.a, posterior oc- clusor scars; ¢.d, hinge area; c.p, car- dinal process; d, chilidium ; s, dental sockets ; v.s, vascu- lar sinuses. angle to the surfaces. In many forms minute tubes more or less closely arranged pierce through the fibrous shell-substance ; but in some genera (Productus) they do not reach the outer surface (see p. 468). Allied genera, however, differ much in the punctate or impunctate character of the shell. SYNOPSIS OF FAMILIES I. EcCARDINES Family. Lingulidae Shell elongated, composed of alternating chitinous and calcareous layers, the latter of which are perforated. Attached by a pedicle passing between apices of valves. Arms have no calcified supports. (For muscles see Fig. 322.) RANGE. — Lower Cambrian to Recent. PRINCIPAL GENERA. — Lingula, Lingulella, Lingulepis. 504. FOSSIL BRACHIOPODA ; CHAP. Family. Obolidae Shell varies in shape. Ventral valve provided with pedicular groove or foramen. Cardinal border thickened. No brachial supports. Shell composed of alternating chitinous and calcareous layers. (For muscles see p. 496.) RANGE. — Lower Cambrian to Devonian. PRINCIPAL GENERA. — Obolus, Obolella, Kutorgina, Linnarssonia, Siphono- treta, Acrotreta, Neobolus. Family. Discinidae Shell rounded, valves more or less conical, fixed by pedicle passing through slit or tubular foramen in ventral valve. No calcified brachial supports. Shell structure chitino-calcareous. RANGE. — Ordovician to Recent. x PRINCIPAL GENERA.— Discina, Orbiculoidea, Trematis. Family. Craniudae Shell calcareous, subcircular; fixed by surface of ventral valve; dorsal] valve the larger, depressed-conical. Shell structure punctate. Four principal muscular scars in each valve, with central triangular pro tuberance in ventral valve (see p. 476). RANGE. — Ordovician to Recent. PRINCIPAL GENUS. — Crania. Family. Trimerellidae Shell thick, calcareous, inequivalve; beak of ventral valve usually prominent; rudimentary teeth may be present; hinge area well developed, with pseudo-deltidium. In interior of valves muscular platform, “crescent,” and sometimes sub-umbonal chambers (see p. 494, Fig. 323). Rance. — Ordovician and Silurian; maximum in Wenlock. PRINCIPAL GENERA. — Trimerella, Monomerella, Dinobolus, Rhinobolus. II. TESTICARDINES Family. Productidae Shell entirely free, or fixed by ventral valve or spines. Concavo-convex, more or less covered with tubular spines. Hinge line straight. Hinge- teeth absent or rudimentary. Cardinal process prominent. Reniform impressions in dorsal valve. (For muscular impressions see p. 501, Fig. 333.) RANGE. — Silurian to Permian. Genus Productus very characteristic of the Carboniferous. PRINCIPAL GENERA. — Productus, Chonetes, Strophalosia, Proboscidella, Aulosteges. XVIII SYNOPSIS OF FAMILIES 505 Family. Strophomenidae Shell very variable in shape ; concavo-convex, plano-convex, or biconvex; hinge line usually straight; frequently with an areaon each valve; foramen may or may not be present. Shell structure near always punctate. Ventral valve usually furnished with hinge-teeth; and dorsal valve with cardinal process. Brachial supports completely absent or very rudimentary. (For muscular impressions see p. 502, Fig. 334.) RANGE. — Wholly Palaeozoic. PRINCIPAL GENERA.— Orthis, with many sub-genera, Clitambonites, Skenidium, Strophomena, Orthothetes, Leptaena, Stropheodonta, Plectambonites. Family. Koninckinidae Shell plano-convex or concavo-convex. Brachial apparatus composed of two lamellae spirally enrolled in the same plane, or in the form of depressed cones, with the apices directed into the ventral valve. RANGE. — Silurian to Lias. PRINCIPAL GENERA. — Koninckina, Koninckella, Coelospira, Davidsonia. Family. Spiriferidae Shell biconvex. Brachial apparatus consisting essentially of two descending calcareous lamellae which by spiral enrolment form a pair of laterally-directed cones (Fig. 330). RanGE. — Chiefly Palaeozoic, but a few forms pass up into the Lias. PRINCIPAL GENERA. — Spirifera, Cyrtia, Uncites, Athyris, Merista. Family. Atrypidae Brachial apparatus consists of two descending calcareous lamellae which bend outwards at the extremity of the crura and are coiled into two spiral cones, the apices of which either converge towards each other (Glassia) or towards the dorsal valve (Atrypa, Fig. 332), or diverge towards the dorsal valve (Dayia); shell structure impunctate. RANGE. — Ordovician to Trias. PRINCIPAL GENERA. — Atrypa, Dayia, Glassia. Family. Rhynchonellidae Shell biconvex, hinge line usually curved. Beak of ventral valve incurved, with foramen. Calcareous brachial supports reduced to a pair of short curved crura. The septa, dental and socket plates may be highly developed and divide up the cavity of the shell into chambers (Stenochisma, Conchidium). Shell structure fibrous, rarely punctate; muscular impressions as in Terebratulidae. Rance. — Ordovician to Recent: majority of the genera are Palaeozoic. PrIncIPAL GENERA. — Rhynchonella (Fig. 327), Stenochisma, Stricklan- diu, Conchidium. 506 FOSSIL BRACHIOPODA CHAP. Family. Terebratulidae Shell structure punctate. Arms supported by a calcareous loop, usually bent back on itself. (For muscular impressions see p. 502, Figs. 328, 329.) Beak of ventral valve perforated by foramen, furnished with deltidium. Rance. — Devonian to Recent; maximum development in Mesozoic times. PRINCIPAL GENERA. — Terebratula, Terebratulina, Waldheimia, Terebra- tella, Kingena, Magas, Centronella. Family. Argiopidae Large foramen for passage of pedicle. Marginal septa present in both valves. Calcareous brachial loop follows margin of shell and is more or less fused with the septa. Shell structure punctate. RanGE. — Jurassic to Recent. PRINCIPAL GENERA. — Argiope, Cistella. Family. Stringocephalidae Shell subcircular, punctate. Cardinal process highly developed, bifid. Brachial apparatus composed of two calcareous free lamellae, prolonged at first downwards, then bent back, upwards and outwards to run parallel to margin of shell and to unite in front, thus constituting a wide loop. RANGE. — Silurian and Devonian. SOLE GENUS. — Stringocephalus. Family. Thecidiidae Shell usually fixed by beak of ventral valve, plano-convex. Sub-cardinal apophysis in ventral valve for attachment of occlusors. Marginal septa in dorsal valve. Calcareous brachial loop more or less fused with shell, and with calcareous spicules of mantle. Shell structure: inner layer fibrous, outer layer tubulated. RanGE. — Carboniferous to Recent. PRINCIPAL GENERA. — Thecidium, Oldhamina. STRATIGRAPHICAL DISTRIBUTION OF BRACHIOPODA It is remarkable that some of the earliest types of Brachio- poda exist generically unchanged at the present day. Such are Lingula, ranging from the Cambrian; Discina and Crania, ranging from the Ordovician; and amongst the hinged forms Terebratula from the Devonian, and Rhynchonella from the Ordovician. In the lowest Cambrian (Olenellus beds) the most important genera are Linnarssonia and Kutorgina. The hinged forms appear in the Cambrian, being represented by Orthis; but the majority in this formation belong to the Ecardines. Lingula, Lingulella, and Obolella are characteristic. ar th XVHI | STRATIGRAPHICAL DISTRIBUTION 507 In the Ordovician many new genera of the Testicardines make their appearance, such as Strophomena, Leptaena, Atrypa, Rhynchonella, Clitambonites, etc., but the extraordinary abun- dance and variety of Orthis is most remarkable. The Ecardines are reinforced by such forms as Trematis and Siphonotreta. It is, however, in the Silurian that the Testicardinate Brachiopoda attain their maximum, for in addition to a great development of species amongst the older forms, a host of new genera for the first time occur here (Spirifera, Athyris, Conchidium, Stricklan- dia, Chonetes, Cyrtia, etc.); and the Trimerellidae are especially characteristic of the Wenlock. 7 With the commencement of Devonian times many species and genera become extinct, but new forms come in (Zerebratula, Orthothetes, Productus, etc.), and some genera are wholly con- fined to this formation ( Uneites, Stringocephalus). The Carbonife- rous is marked by the maximum development of Productus and Spirifera; Orthothetes, Stenochisma, and Athyris are also abun- dant, but there is a considerable extinction of the older genera and species, and a great diminution in the number of oe and species of those that persist. A further reduction occurs in the Permian, where the most important genera are Productus, Strophalosia, and Stenochisma; but Aulosteges is a new form peculiar to this period. In the Trias a new era commences; the principal families and genera of the older rocks disappear entirely; a few spire-bearing genera persist (Spiriferina, Athyris), and the genus Koninckina is restricted to this formation. The enormous development of species of the Terebratulidae and Rhynchonellidae is the most noticeable feature in Jurassic times; and a few ancient types linger on into the Lias (Sperv- ferina, Suessia, asub-genus of Spirifera); Koninckella here occurs. The Cretaceous Brachiopoda are closely allied to the Juras- sic; Magas and Lyra are peculiar to the period, and the Tere- bratulidae and Rhynchonellidae are very abundant, together with the Ecardinate genus Crania. With the commencement of Tertiary times the Brachiopoda have lost their geological importance, and have dwindled down into an insignificant proportion of the whole Invertebrate fauna. _ The distribution of the Brachiopoda in past time is shown in the following table: — 508 _ FOSSIL BRACHIOPODA CHAP. Palaeozoic Mesozoic Cambrian Deyonian Carboniferous Permian Jurassic Cretaceous Tertiary hy ECARDINES Lingulidae Iimgula eee eee ee aimeclellarey ye. aes Obolidae Obolus . Obolella Kutorgina . Linnarssonia . Trematis ; Siphonotreta . Acrotreta . Discinidae Discina . Craniidae Crania .« Trimerellidae Trimerella. Dinobolus . | TEE fee | | | Silurian TESTICARDINES Productidae Productus. . ad oy Aaa aoe Chonetes . . eens |e Lee Strophalosia eet! Strophomenidae.. -Orthis gy ye) use) eases eee ee oe Skenidium. Clitambonites Strophomena . Stropheodonta a Leptaena hess Orthothetes . poe Pe He |e Davidsonia ts Koninckinidae Koninckina . Los Koninckella. . mre. Spiriferidae Spirifera . . SEAN, Spiriferina . Oyirtian. .) Laas Syringothyris . Wncites. 63). Athyris. Merista . Retzia . Atrypidae Atrypa . Dayia Coelospira . Rhynchonellidae Rhynchonella Stenochisma . Stricklandia Conchidium Terebratulidae Terebratula Terebratulina Waldheimia Terebratella Kingena Magas : Centronella Argiopidae Argiope . Cistella . Stringocephalidae Stringocephalus Thecidiidae Thecidium. Oldhamina XVII PHYLOGENY AND ONTOGENY 509 PHYLOGENY AND ONTOGENY Wherever successive stages in the life history of an individual resemble in important anatomical features the adult individuals of other species occurring in successive members of a strati- graphical series, the development of the individual may be regarded as an epitome of the development of the species; it also generally throws light on the origin and relationships of allied genera and families. In the case of the fossil Brachiopoda comparatively little work has yet been done in tracing their ontogeny or phylogeny, though the abundance, variety, and excellent state of preserva- tion of the extinct species offer a promising field for investi- gation. It is to Dr. C. E. Beecher and other recent American palaeontologists that we owe our advance in this branch of the subject. In the first place, in about forty genera, representing nearly all the leading families of the group, the important fact has been established of the presence of a common form of embryonic shell, termed the “ protegulum,” which is “semicircular or semi- elliptical in shape with a straight or arcuate hinge line and no hinge area” (Beecher).! Its minute size and delicate texture cause its preservation to be rare, but its impression is not uncommonly left on the beak of the adult shell. The main features of this embryonic shell are exhibited in the adult Lower Cambrian Brachiopod Obolus ( Kutorgina) labra- doricus (Billings); the sub-equal semielliptical valves have lines of growth running concentrically and parallel to the margin of the shell, and ending abruptly against the straight hinge line; and this indicates that there has been no change in the outline and proportions of the shell during its stages of growth, but only a general increase in size. It is very significant that we have here a mature type possessing the common embryonic characters of a host of widely separated genera, and we may therefore regard it as the most primitive form known. Many genera pass through this so-called “ Paterina”’ stage either in the case of both their valves, or more generally in the case of the dorsal valve only; but modifications in the form of the protegulum arise, which are due to the influence of 1 Amer. Jour. Science, 1890-1893. 510 FOSSIL BRACHIOPODA CHAP. accelerated growth, by which features belonging to later stages’ become impressed on the early embryonic shell. The most variable and specialised valve — the ventral or pedicle valve — naturally exhibits the effect of this influence first and to the greatest extent. The Palaeozoic adult forms of many species represent various pre-adult stages of the Mesozoic, Tertiary, and Recent species, as is especially well shown in the genera Orbi- culoidea and Discinisca. In the Strophomenoid shells the protegulum in the dorsal valve is usually normal, but in the ventral valve abbreviation of the hinge and curvature of the hinge line are produced by acceleration of the “ Discinoid stage” in which a pedicle notch is present. No marked variation has yet been noticed in the spire-bearing, or Terebratuloid, or Rhynchonelloid genera. The form of the shell and the amount of difference in shape and size of the valves seem to be largely due to the length of the pedicle and its inclination to the axis of the body, as evi- denced by the development of Terebratulina. A series showing progressive dissimilarity of the two valves arising from these causes can be traced from Lingula to Crania. The greater alteration that takes place in the ventral valve appears to be due to its position as lower and attached valve. If the pedicle is short a transversely-expanded shell with long hinge line results when the plane of the valves is vertical or ascending, but when the latter is horizontal a Discinoid form is found. This mode of attachment is often accompanied by a more or less plainly developed radial symmetry. Shells with long pedicles, on the other hand, are usually longer than wide. The character of the pedicle-opening is of great significance » from an evolutional and classificatory point of view, for the successive stages through which it passes in embryonic growth are chronologically paralleled by different genera, and are like- wise accompanied by the successive acquisition of other important anatomical characters, as has been shown by Beecher and others. The first and simplest type of pedicle opening is in shells with a posterior gaping of the valves, where the pedicle protrudes freely between them in a line with the axis, and the opening is shared by both valves, though generally to a greater extent by the ven- tral valve. Paterina (= Obolus labradoricus) and Lingula furnish XVII PHYLOGENY AND ONTOGENY 511 examples of this type. In the second type the pedicle opening is restricted to the ventral valve, and the direction of the pedicle makes a right angle with the plane of the valves; in the lower forms the pedicle les in a slit or sinus (7rematidae), but by fur- ther specialisation it becomes enclosed by shell growth so as to lie within the periphery, and finally becomes subcentral in some genera (Discinidae). The third type shows the pedicle opening confined to the ventral valve and submarginal. A pseudo-delti- dium may preserve the original opening ( Clitambonites) ; or this shelly plate may become worn away or reabsorbed in the adult so that the deltidial fissure through which the pedicle passes remains quite open (Orthidae). In the fourth type the incipient stage marks a return to the simple conditions of the first type; but ultimately a pair of deltidial plates develop, and may com- pletely limit the pedicle opening below. Examples of this type are Spirifera and Rhynchonella. By means of these four types the Brachiopods have been divided into four Orders: the Aére- mata (type 1.); the WNeotremata (type i.); the Protmemata (type i.); and the Telotremata (type iv.). The Telotremata were the last to appear, but the four types of pedicle-opening with the various forms of calcareous brachial apparatus were in existence in the Bala period of the Ordovician. As Paterina isthe most primitive form of all, we may place it at the root of the phylogenetic tree. From itsprang the Atremata, which gave off the Neotremata and Protremata; the most primi- tive Neotremata seem to be the Trematidae, while the connecting link between the Protremata and Atremata is furnished by the Kutorginidae. From the genus Conchidiwm and its allies we may see how the Rhynchonellidae ushered in the Telotremata as an offshoot from the Protremata. The Telotremata subsequently gave off two main branches, which became specialised with the loop-bearing and spire-bearing forms respectively. The evolution and mutual relationships of genera have been indicated with much probability by Hall, Clarke, and others. The Obolelloid type may be connected with the Linguloid by means of Lingulella and Lingulepis, while in Lingula itself we find the point of divergence for the ancestors of Zrimerella, and for a line of variation culminating in Dignomia. The Palaeo- zoic Rhynchonelloids branched off at an early period from the same stock as Orthis, and are connecting links between this ~~ 512 FOSSIL BRACHIOPODA CHAP. XVITI genus and Mesozoic Rhynchonellae ; and a whole series of genera exhibit intermediate stages of structure between the Rhyncho- nelloid and Pentameroid groups. The Terebratuloids can be traced back to the primitive type Renssoellaria; and amongst spir e-bearing forms, the protean genus Spirifera can be split up into groups of species which diverge along lines tending to forms no longer congeneric. When we come to deal with specific differences we find frequently such a host of intermediate varie- ties that the separation of many species, as in the case of Mesozoic Terebratulae, is to a large extent arbitrary and artificial. INDEX References to figures are printed in thick type (248, 197); to systematic position, in italics (391, 430) ABRALIA, 391 | Aeolis, 10, 152, 432; radula, 217, Absorption of internal portions of 229; stinging cells, 65; mimicked shell, 259 by Sagartia, 68; warning colora- Abyssal Mollusca, 374 tion, 72 Acanthinula, 441 Aerope, 328, 338, 440; radula, 215; Acanthoceras, 399 habits, 54 Acanthochiton, 408, 403 Aestivation, 25 Acanthodoris, 434 Aetheria, 328-336, 452 ; variation, 92 Acanthopleura, 403 ; eyes, 188 Africarion, 333, 440 Acavus, 303, 304, 335, 441 Acera, 245, 430 Achatina, 278, 328-337, 383, 442, 448; jaw, 211; food, 33; size of egg, 124; A. fulica, 279 Achatinella, 278, 326, 327, 443; radula, 234 ; musical sounds, 51 Achatinelloides, 332 Acicula, 287, 296, 414 Acmaea, 405 ; radula, 227 Acme, 414 Acmella, 314, 415 Acroptychia, 336, 414 Acrotreta, 504, 508 Actaeon, 250, 427, 428, 429; radula, 217, 280; streptoneurous, 203 n. Actaeonella, 430 Actaeonia, 432 Actaeonina, 250, 429 Actinoceras, 394 Actinodonta, 447 Acusta, 306, 316, 318, 441 Adacna, 12, 297, 455 Adalaria, 434 Adamsiella, 414 Addisonia, 412 Adelphoceras, 395 Adeorbis, 416 Agaronia, 426 Age of snails, 39 Aglossa, 7 Agnatha, habits, 51 Akiodoris, 434 Alaba, 415 Alaria, 418 Alariopsis, 420 Albersia, 320 Albino varieties, 87 Alcadia, 348-851, 410 Alderia, 432 Alexia, 439 Alicia, 459 Allognathus, 441 Allopagus, 452 Alloposidae, 384 Alvania, 415 Alycaeus, 266, 302 f., 309, 319, 414 Amalia, £440 Amalthea, 78 Amaltheus, 398 Amastra, 443 Amaura, 411 Amberleya, 409 Ambonychia, 449 Amicula, 404 Ammonites, 247, 393, 398, 398; sutures, Admete, 426 396 ; aptychus, 397 Aegires, 434 Ammonoidea, 396 f. Aegista, 305, 316, 441 Amnicola, 325, 415 Aegoceras, 398 | Amoria, radula, 222 VOL. II 513 . 25 514 Ampelita, 335, 442 Amphibola, 10, 18, 439; breathing, 151; radula, 236 Amphibulimus, 352, 442; radula, 233 Amphidoxa, 358 Amphidromus, 301, 305, 317, 310, 359, 442; radula, 2383 Aimphineura, 8, 400; breathing organs, 154, 168 ; nervous system, 208 ; geni- talia, 145 Amphipeplea, 439 Amphiperas, 419 Amphisphyra, 430 Amphissa, 423 Amphitretus, 383 Anmpullaria, 17, 416; self-burial, 42 ; spawn, 125; breathing organs, 151, 158 ; jaws, 212; shell, 249, 265; oper- culum, 268; distribution, 294, 320, 322, 343, 359 Ampullarina, 802, 439 Ampullina, 411 Amussium, 450 Amycla, 423 Anabathron, £415 Anachis, 423 Anadenus, 24, 441 Anal glands, 241 Anal siphon, 164, 173 Anastomopsis, £442 Anatina, 274, 275, 459 Anatinacea, 458; gills, 167 Anaulus, 414 Anchistoma, 298, 296 Ancilla, 267, 426 Ancillina, 426 Ancistrochirus, 391 Ancistromesus, 405 Ancistroteuthis, 391 Ancula, 434; radula, 229, 230; warn- ing coloration, 72 Anculotus, 417 Ancyloceras, 247, 399 Ancylus, 19, 439; breathing, 162; hibernating, 27; radula, 235 Aneitea, 325, 443 Angitrema, 340, 417 Anisocardia, 451 Anodonta, 259, 341, 452; shower of, 47; variation, 92 ; Glochidium, 147; gill, 167 ; otocyst, 197; nervous system, 206 ; hinge, 274; A. anatina, 24; dis- tribution, 282 Anodontopsis, 451 Anoglypta, 325, 441 Anomia, 257, 448, 464; intestine, 241; byssus hole, 262; hearing, 196 Anomiacea, 448 Anoplophora, 451 Anostoma, 248, 266, 356, 358, 442; aperture, 63 Anthracosia, 451 MOLLUSCA — BRACHIOPODA Anura, 424 Anus, 209, 241 Apera, 334, 440 Aperostoma, 344, 414 Aphanotrochus, 408 Aphelodoris, radula, 230 Apicalia, 422 Aplacophora, 9, 404; radula, 228 Aplecta, 354, 439 Aplustrum, 245, 428, 430; radula, 230 Aplysia, 245, 428, 431; stomach, 239; purple fluid, 65 Aplysioidea, 430 Aporrhais, 418 ; radula, 215 Apricardia, 455 Aptychus, 397 Aptyxiella, 417 Aptyxis, 424 Aral Sea, Limnaea from near, 84; Cardium from, 91 Arca, 14, 171, 273, 448; eyes, 191 Arcacea, 448 Arcachon, oyster-parks at, 105 Arcestes, 397 Archidoris, 434, 434; protective colora- tion, 73 Architeuthis, 378, 390, 390 ; sucker, 381 Arcomya, 458 Arconaia, 307, 452 Arctic shells, colour of, 86 Arcuella, 422 Argiope, 470, 472, 479, 487; parasite of, 485; distribution, 486; fossil, 501, 506, 508 Argiopidae, 506, 508 Argobuccinum, 420 Argonauta, 383, 383; egg-laying, 127; hectocotylised arm, 137; radula, 236 Arinia, 413 Ariolimax, 441, 341, radula, 233 Arion, £40 ; shell, 175, 245, 246 ; hardier than Helix, 24; voracity, 30 f.; egg- laying, 42 f.; protective coloration, 70; pulmonary orifice, 160; food, 179; smell, 193 f.; radula, 233; dis- tribution, 285 | Arionta, 841, 353, £41 Ariophanta, 301, 308, 309, 316, 440; protective coloration, 70 Aristotle, on modified arm of polypus, 138 Artemis, 454 Arthuria, 403 Asaphis, 456 Ascoceras, 394 Ascoglossa, 11 n., 437 Ashford, C., on pulsations of heart in Helix, 26; on homing of Helix, 35; on dart-sac, 148 Asolene, 416 Aspergillum, 262, 459 Aspidelus, 329, 440 INDEX 515 Aspidoceras, 399 Assiminea, 415 Astarte, 451 Asthenothaerus, 459 Astralium, 409 Athoracophorus, 445 — see Janella Athyris, 499, 500, 505 ; stratigraphical distribution, 507, 508 Atilia, 423 Atlanta, 421, 422; foot, 200 Atopocochlis, 3380, 441 Atremata, 511 Atretia, distribution, 486, 487 Atrypa, 501, 502, 505; stratigraphical distribution, 507, 508 Atrypidae, 501, 505, 508 Aturia, 893, 395 Atys, 428, 430 Aucapitaine, H., on tenacity of life, 38 | Aucella, 449 Aulopoma, 157, 304, 414; operculum, 269 Aulosteges, 504; stratigraphical distri- bution, 507 Auricula, 489, 439 Auriculella, 327, 443 Auriculidae, 17, 18, 260, 489, 439; lung, 160; eyes, 186; radula, 235 Austenia, 301, 304, 440 Avellana, 430 Avicula, 254, 258, 449, 449; eyes, 190; genital orifice, 242 ; A. margaritifera, 100 Aviculopecten, 450 Aviculopinna, 449 Axinus, 452 Azeca, 442 Azygobranchiata, 155, 407 BABINKA, 447 Bactrites, 395 Baculites, 399 Baikalia, 290, 415 Baird, Mr., on the British Museum snail, 37 Balea, 442; B. perversa, 24, 41 Baltic, fauna of the, 12, 83, 366 Bankivia, 408 Barbatia, 448 Barleeia, 415 Barnacle, Rev. H. G., on musical sounds, produced by Mollusca, 51 Barometers, snails as, 50 Bartlettia, 452 Basilissa, 376, 408 Basommatophora, 11, 19, 181, 438 Basterotia, 451 , Bateson, W., on variation in Cardium, 91; on hearing in Anomia, 196 Bathmoceras, 395 Bathydoris, 433 Bathyteuthis, 390 | ; Batissa, 320, 453 Beddomea, 304 Beecher on phylogeny, 509 Beetles, prey on Mollusca, 58 Bela, 426 ; radula, 219 Belemnites, 380 | Belemnitidae, 387 Belemnosepia, 390 Bellerophon, 266, 407 | Belopetra, 380 Belopteridae, 388 Belosepia, 386, 388 Beloteuthis, 390 Bembix, 376, 408 Benedictia, 290, 415 Benthobia, 877 Benthodolium, 377 Berendtia, 441 Beudant, experiments on Mollusca, 12 Bideford Bridge and mussels, 117 Binney, Dr., on epiphragm, 28 Binneya, 341, 441 Biradiolites, 456 Birds, devour Mollusca, 56 f. Bithynella, 289, 293, 415 Bithynia, 336, 342, 415 ; stomach, 239 ; habitat, 25 Bittium, 416 Blaesospira, 346, 351 Blandiella, 16, 414 Blanfordia, 414 Blind Mollusca, 185 Blood, 171 Bodo, land Mollusca, 24 Boeuf and French oysters, 107 Bolma, 409 Boltenia, 346 Boreofusus, radula, 221 Bornella, 433 ; stomach, 239 Borsonia, 426 Borus, 356-358, 441 Bourcieria, 357, 410 Bourguetia, 417 Bourguignatia, 3382 Bouvier — see Fischer Boysia, 302, 442 Brachial apparatus, types of, 500 Brachiopoda, fossil, limestone formed of, 492; shell, 493, 497 ; muscle scars on, 494, 501; platform, 495; synopsis of families, 503 ; stratigraphical dis- tribution, 506; phylogeny and onto- geny, 509; Orders, 511 Brachiopoda, recent, 463; historical account of, 464; shell, 465; body, 469; digestive system, 471; body cavity, 472; heart, 473; excretory organs, 474; muscles, 475; nervous system, 478; reproductive system, 478; embryology, 479; habits, 482 ; distribution, 484; classification, 487 ; affinities, 487 516 Brachytrema, 417 Brackish-water species, 14 Branchiae, 151, 153, 164 Branchial siphon, 155, 164, 173 Braun, on self-impregnation, 44 Breathing organs—see Respiration, Branchiae Brechites, 459 Breeding, periodicity in, 129 Broderipia, 408 Brotia, 305 Brownia, 188 Buccinanops, 423 Buccinopsis, 424; radula, 221, 222; egg-laying, 128 Buccinum, 6, 424; radula, 217; mon- strosity, 251 ; breeding, 129 ; osphra- dium, 195; spawn, 126 Buliminus, 24, 278, 285, 295 f., 316, 331, 339, 442; protective habits, 70 ; B. pallidior, 38 Bulimulus, 278, 384, 339-359, 442; jaw, 211, 233; radula, 2383; varia- tion, 87 Bulimus, 278, 342-359, 355, 441; radula, 238; egg, 124 Bulinus — see Isidora Bulla, 428, 430 Bullia, 155, 423; habits, 192; foot, 198; radula, 221 Bulloidea, 429 Burrowing Mollusca, 446 Burying propensities of Mollusca, 27, 41 Busycon, 424; money made from, 97 ; egg-capsules, 125—see Fulgur Butterell, Mr., on habits of Testacella, 52 Byssocardium, 455 Byssus gland, 201 CADLINA, 484 Cadoceras, 393 Cadulus, 376, 445 Caecilianella, 442; habitat, 48 ; eyes, 186 Calcarella, 138 California, land Mollusca, 280 Calliostoma, 408 ; jaws, 212 Callistochiton, 403 Callochiton, 408 Callogaza, 408 Callonia, 442 Callopoma, 409 Calma, protective coloration, 74 Calybium, 410 Calycia, 820, 442 Calycidoris, 434 Calyptraea, 248, 412 Camaena, 305, 306, 315, 316, 447 Cambrian, Mollusca of the, 2 Camitia, 409 MOLLUSCA — BRACHIOPODA Campaspe, 433 Camptoceras, 302 Camptonyx, 278, 302, 439 Campylaea, 285, 289 f., 298, 447 Canal, 155 Cancellaria, 426 Canidia, 16, 305, 423 Cannibalism in snails and slugs, 32, 33 Cantharidus, 408 Cantharus, 275; radula, 222 Caprina, 456 Caprotina, 456 Capulus, 412 Caracolus, 347-851, 441 Carbonicola, 451 Cardiacea, 454 Cardiapoda, 421 Cardilia, 454 Cardinal plate, 500 Cardinal process, 497, 501 Cardinalia, 408 Cardinia, 451 | Cardita, 278, 451 Carditella, 451 Carditopsis, 451 Cardium, 6, 273, 455, 455; C. edule, 12, 164; modifications, 12; variation, 84, 91; nervous system, 207; distri- bution, 292, 297 Carelia, 327, 443 Carinaria, 9, 422, 422; foot, 200 Carinifex, 439 Carolia, 448 Cartusiana, 296 Carychium, 18, 439 Caryodes, 325, 359, 441 Casella, radula, 230 Caspta, 12, 297 Caspian Sea, fauna, 12, 297 Cassidaria, 420 Cassidula, 18, 278, 489, 439 Cassis, 255, 420; radula, 223 Castalia, 344, 452 Cataulus, 157, 266, 304, 474 Caterpillars mimicking Clausilia, 68 Cathaica, 316, 441 Catinella, 443 Cavolinia, 158, 486; eyes, 186 Cecina, 414 Cenia, 432; breathing, 152 Centrodoris, 434; radula, 280 Centronella, 499, 506, 508 Cephalopoda, 378 f.; defined, 5; ink, 65; egg-laying, 127; embryo, 138; branchiae, 168; osphradium, 195; foot, 200; nervous system, 206; jaws, 218; radula, 236 Cepolis, 349-851, 441 Cerastoma, 423 Cerastus, 331, 441 Cerata of Nudibranchs, 71, 159 INDEX Ceratites, 397, 398; suture, 396 Ceratodes, 357, 416 Ceres, 21, 354, 410 Ceritella, 417 Cerithidea, 260, 417 ; C. obtusa, breath- ing, 152 Cerithiopsis, 417 Cerithium, 16, 416 Ceromya, 458 Chaetoderma, 404, 404; breathing organs, 154; nervous system, 208; radula, 217, 228 Chaetopleura, 403 Chama, 257, 272, 446, 455 Chamostrea, 458 Changes in environment, effect of, 83 f. Chank-shell, fishery of, 100 Charis, 324, 442 Charopa, 319, 823-827, 441 Chascax, 424 Chelinodura, 430 Chelotropis, 133 Chenopus, 418 Chilidium, 498 Chilina, 19, 343, 358 Chilinidae, 439; radula, 236 Chilotrema, 441 China, use of shells in, 101 Chiropteron, 133 Chiroteuthis, 385, 391 Chiton, 8, 153, 403; egg-laying, 126; | breathing organs, 153 f.; eyes, 188; osphradium, 195; radula, 228; ner- vous system, 203; valves, 401, 402 ; girdle, 403 = Chitonellus, 404, 404; valves, 401 Chittya, 16, 348, 351, 414 Chlamydephorus, 333, 440 Chlamydoconcha, 175, 245, 453 Chlamys, 450 Chloritis, 306, 311, 319-824, 441 Chlorostoma, 408 Chlorostracia, 307 Choanomphalus, 250, 290, 439 Chondrophora, 389 Chondropoma, 346-355, 348, 414 Chondrula, 285, 295, 296, 442 Choneplax, 404 Chonetes, 504; stratigraphical distribu- | tion, 507, 508 Choristes, 420 Choristoceras, 398 Chorus, 423 Chromodoris, 434; jaws, 212; radula, 230 Chrysallida, 422 Chrysodomus, 423 Chrysostoma, 409 Cingula, 415 Cingulina, 422 Cionella, 442 Circe, 454, 458 517 Circulatory system, 169 Circulus, 408 Circumpolar species, 287 Cirrhoteuthis, 381, 382 Cistella, 467, 470, 472, 475, 476, 479, 480, 487 ; larvae, 481, 483; parasite of, 485 ; listribution, 486 ; fossil, 506, 508 Cistopus, 385 Cistula, 349, 351, 355, 414 Cladohepatica, 432 Clanculus, 408 Classification, 5, 8 ; of Gasteropoda, 8, 11 Clathurella, 426 Clausilia, 442, 442; mimicked by cater- pillars, 68; monstrosity, 251; dis- tribution, 285 f., 294, 305-318, 332, 339-356 ; C. rugosa, 24 ; scalaris, 278 Clavagella, 262, 459 Clavator, 385, 359, 441 Clavatula, 426 Clavella, 424 Claviger, 329, 417 Clea, 16, 305, 423 Clementia, 454 Cleodora, 436, 436 Cleopatra, 294, 328, 331, 336, 416 Clessin, on duration of life, 39 Clessinia, 12, 297 Clio, 436, 436 Cliona, enemy of oysters, 112 Clione, 158, 438 Clionopsis, 437 Clitambonites, 498, 505; stratigraph- ical distribution, 507, 508, 511 Clithon, 327, 410 Clydonites, 398 Clymenia, 397 Clypidella, 406 Cocculina, 408 Cochlicella acuta, 278 Cochliolepas, 77 Cochloceras, 398 Cochlodésma, 459 Cochlostyla, 124, 278, 318, 315, 441 Cockles, use of, 101, 118 Coecum, 247, 260, 417, 418 Coeliaxis, 334, 442; habitat, 49 Coelocentrum, 353, 442 Coelospira, 505, 508 Cold winter, effect on oysters, 112 ; on mussels, 116 Collinge, W. E., on growth and burial of shells, 41 Collisella, 405 Collisellina, 405; radula, 227 Collonia, 409 Colobocephalus, 430 Colour of arctic shells, 86 Colpodaspis, 430 Columbarium, 426 518 MOLLUSCA — BRACHIOPODA Columbella, 423; radula, 222 Columbellaria, 420 Columbellina, 420 Columna, 828, 330, 443 Cominella, 16, 424 Composition of shell, 252 Concha, 463 Conchidium, 497, 498, 500, 505 ; strati- graphical distribution, 507, 508, 511 Concholepas, 267, 423 Conidea, 423 Conocardium, 455 Conorbis, 426 Conus, 247, 275, 426; poisonous bite, 65; tooth, 66; shell, 69, 255, 260; mimicked by Strombus, 69; prices | given for rare, 121; spawn, 125; | radula, 218, 220; operculum, 269 Cookia, 409 Coptochilus, 814, 414 | Coralliophaga, 451 | Coralliophila, 75, 423 Coralliophilidae, radula, 216 Corambe, 434 Corasia, 311, 319-821 Corbicula, 15, 288, 292 f., 453 Corbis, 452 Corbula, 456 Corilla, 303 Corona, 27, 442 Coronaria, 297 Coryda, 346-851, 441 Coryphella, 432 Cosmoceras, 399 Cowry used as money, 96 Coyote trapped by Haliotis, 57 Cranchia, 391 Crania, 464, 467, 468, 469, 471, 472, 473, 475, 476, 477, 487; distribu- tion, 485 ; fossil, 493, 494, 504; strati- graphical distribution, 506, 507, 508, 510 Craniidae, 487, 496, 504, 508 Cranopsis, 265, 406 Craspedochiton, 403 Craspedopoma, 298, 414 Craspedostoma, 408 Crassatella, 451 Cratena, 432 Crawling of Helix, 45 Cremnoconchus, 16, 302, 413 Crenatula, 75, 449 Crenella, 449 Orenipecten, 450 Crepidula, 248, 257, 412, 412; para- sitic, 78 Crepipatella, 248, 412 Oreseis, 486, 436; eyes, 186 Crimora, 434; radula, 229 Crioceras, 247, 399, 399 Cristigibba, 311, 319, 820, 441 Crossostoma, 408 Crucibulum, 248, 412 Cryptochiton, 245, 871, 402, 404 Cryptochorda, 425 Cryptoconchus, 404 Cryptophthalmus, 430 Cryptostracon, 353, 441 Ctenidia, 151 — see Branchiae Ctenopoma, 346-851, 414 Cucullaea, 274, £48 Cultellus, 457 Cuma, 423 Cumingia, 453 Cuspidaria, 459; branchiae, 168 Cuvierina, 486, 436 Cyane, 410 Cyathopoma, 247, 268, 314, 338, 414 Cyclas, 453; veliger, 182; ova, 146; otocyst, 197 ; C. cornea, thread-spin- ning, 29; distribution, 282 Cyclina, 454 Cyclobranchiata, 156 Cyclocantha, 409 Cyclomorpha, 414 Cyclonassa, 423 Cyclonema, 409 Cyclophoridae, origin, 21 Cyclophorus, 302, 806-819, 329-334, 344, 352-358, 414 ; jaws, 212; radula, 21 Cyclostoma, 328, 381-338, 414, 414; stomach, 239; vision, 184; osphra- dium, 195 ; nervous system, 205; C. elegans, 287, 288 Cyclostomatidae, origin, 21; radula, 224; gait, 199 Cyclostrema, 408 Cyclosurus, 247, 337, 414 Cyclotopsis, 388, 414 . Cyclotus, 296, 319, 320, 414 Cylichna, 428, 430; radula, 215 Cylindrella, 247, 260, 278, 343-355, 348, 442; monstrosity, 251, 252 Cylindrellidae, radula, 233, 234 Cylindrites, 430 Cylindrobulla, 430 Cylindromitra, 425; radula, 222 Cymbium, 255, 367, 425; radula, 221 Cymbulia, 437 Cymbuliopsis, 437 Cynodonta, 424 Cyphoma, 419 Cypraea, 178, 419; prices given for rare, 122; mantle-lobes, 177, 178; radula, 224; shell, 255, 260, 261; C. moneta, 96 Cypraecassis, 420 Cypraedia, 419 Cypraeovula, 419 Cyprimeria, 454 Cyprina, 451 Cyrena, 15, 458 ; Cyrenella, 458 distribution, 285, 294 INDEX Cyrtia, 505; stratigraphical distribu- tion, 507, 508 Cyrtoceras, 394 Cyrtodaria, 457 Cyrtodonta, 452 Cyrtolites, 407 ~ Cyrtonotus, 448 Cyrtotoma, 414 Cysticopsis, 346-351, 441 Cystiscus, 425 Cystopelta, 325, 326, 440 Cytherea, 454, 454 DACRYDIUM, 449 Daedalochila, 441 Dall, W. H., quoted, 35; on branchiae, 164 Damayantia, 440 Daphnella, 426 Darbyshire, R. D., on tenacity of life, 39 Dardania, 415 Dart-sac, 142 Daudebardia, 289, 292 f., 440 Davidsonia, 505, 508 Dawsonella, 410 Dayia, 505, 508 Decapoda, 386 f. Decollation, 260 Deep-sea Mollusca, 374 De Folin, experiment on Cyclostoma, 157 Deianira, 410 Delage, experiments on otoeysts, 197 Delphinula, 409 Deltidium, 499 Dendronotus, 433; protective colora- tion, 72; habits, 51 Dentalium, 6, 444, 445; used as money, 97 ; veliger, 181; radula, 228 Dentellaria, 350-355, 441 ; aperture, 63 Desert species, 25, 85 Deshayesia, 411 Desmoulea, 423 Development of fertilised ovum. 130 f. Dexiobranchaea, 437 Diadema, 414 Diala, 4165 Dialeuca, 441 Diaphora, 314 Diaphorostoma, 412 Diastema, 418 Diastoma, 417 Diaulula, 434 Dibaphus, 425 Dibranchiata, 380; eye, 183; nervous system, 207 Diceras, 269, 455 Didacna, 12, 297, 455 : Differences of sex, 133 Dignomia, 511 Digonopora, 134, 144 519 Diloma, 408 Dimorphoptychia, 410 Dimya, 450 Dinobolus, 504, 508 Dinoplax, 403 Ditocardia, 9, 170, 405 f. Diplodonta, 452 Diplommatina, 302-3827, 413 Diplomphalus, 322, 328, £440 Diplopoma, 346, 351, 414 Dipsaccus, 424 Dipsas, 307 Discina, 464, 468, 471, 475, 487 ; distri- bution, 485 ; fossil, 493, 504; strati- graphical distribution, 506, 508 Discinidae, 487, 496, 504, 508, 511 Discinisca, 487, 510 ; distribution, 485, 486 Discites, 395 | Discodoris, 434 Discosorus, 394 Distortio, 255 —see Persona Ditropis, 312, 314, 414 Docoglossa, 227, 405 Dolabella, 428, 431 Dolabrifer, 431 Dolium, 419; acid secretion, 237 Donax, 269, 446, 453 Dondersia, 404 Dorcasia, 3385, 441 Doridium, 430 Doridunculus, 434; radula, 229 Doriopsis, 434 Doris, breathing organs, 159; radula, 230 Dorsanum, 423 Dosidicus, 390 Dosinia, 454 Doto, 433 ; protective coloration, 71 Dreissensia, 14, 123, 452 ; hibernation, 26; singular habitat, 48; veliger, 132, 146; eyes, 192 Dreissensiomya, 452 Drepania, 434 Drillia, 426 Drymaeus, 356, 442 Dryptus, 356, 441 Durgella, 301, 304, 440 Dwarf varieties, 88 Dybowskia, 290 EASTONIA, 454 Eburna, 267, 424; radula, 220 Ecardines, 466; muscles, 476; fossil, 493 ; families, 487, 503, 508 Eccyliomphalus, 413 Echinospira, 133 Edentulina, 338 Egg-laying of Arion, 42 f.; of Mollusca generally, 123 Eglisia, 411 Hider-duck, shells used by, 102 520 Elaea, 322, 440 Elasmoneura, 411 Eledone, 385, 385; radula, 286 © Elizia, 456 Elysia, 432; protective coloration, 73 ; breathing, 152 ; radula, 217, 280, 482 Emarginula, 265, 406 Embletonia, 429 Emmericia, 415 Ena, 296, 442 Enaeta, 425 Endoceras, 394 Endodonta, 325, 334, 441 Engina, 424 Enida, 408 Ennea, 298, 302, 306, 309, 314, 316, 328-337, 440, 440; habits, 54; £. bicolor, 279 Enoplochiton, 403, 403 Enoploteuthis, 391 Ensis, 457 Entocolax, 77, 79, 152 Entoconcha, 77, 79, 152, 216 Entovalva, 77, 82 Ephippodonta, 453; commensal, 81 Epidromus, 420 Epiphragm, 26, 27 f. Epipodia, 427 Erato, 419 Eremophila, 294 EHrgaea, 248, 412 Erinna, 327, 439 Erosion, 276 : Ervilia, 454 Erycina, 453 Escargotiéres, 119 Estria, 329, 440 Estuarine species, 14 Ethalia, 409 Eucalodium, 260, 353, 442 Euchelus, 408 Euchrysallis, 420 Eudioptus, 442 Eudoxochiton, 403 Euhadra, 316, 318, 441 Eulamellibranchiata, 451; gill, 166, 167 Eulima, 422; parasitic, 77, 79 Eulimella, 250, 422 Eulota, 296, 441 EHuomphalus, 247, 413 Euplecta, 440 Eupleura, 423 Euplocamus, 434 Eurybia, 438 Eurycampta, 346-351 Eurycratera, 349, 351, 441 Eurystoma, 304 Eurytus, 442 Euthria, 424 Euthyneura, 203 Eutrochatella, 8347-351, 348, 410 MOLLUSCA — BRACHIOPODA Exploring expeditions, 362 Eye in Mollusca, 181 f. FACELINA, 432 Fasciolaria, 424; radula, 221 Fastigiella, 416 Favorinus, 432 Fenella, 415 Fertilised ovum, development, 130 f. Ferussacia, 291, 298, 297 f., 442 | Fiji islanders, use of shells, 98 Filibranchiata, 448 ; gill, 166 Fiona, 432; radula, 217 | Firoloida, 421 ' Fischer and Bouvier, on breathing of Ampullaria, 158 Fischeria, 15, 328, 453 Fish devour Mollusca, 59 Fissurella, 265, 406 ; breathing organs, 153; apical hole, 156; nervous sys- tem, 204; radula, 227 ; growth, 261 Fissurellidaea, 406 Fissuridea, 406 Fissurisepta, 406 ‘Fistulana, 262, 457 Flabellina, 432 Fluminicola, 415 Folinia, 415 Food of Mollusca, 30 f. ; Mollusca as food, 102 f. Foot, 198; in classification, 5 Forel, on deep-water Limnaea, 162 Formation of shell, 255 Fortisia, 429 Fossarina, 413 Fossarulus, 802, 415 Fossarus, 4138 Fourth orifice in mantle, 174 Fresh-water species living in sea, 12; frozen hard, 24 Frogs and toads devour Mollusca, 58 Fruticicola, 285, 290, 316, 318, 441 Fruticocampylaea, 296 Fryeria, 434 Fulgur, 249, 424 Fusispira, 420 Fusus, 262, 424 GADINIA, 152, 431; breathing, 18, 151; classification, 19; radula, 217, 230 Gain, W. A., quoted, 32, 33, 39; on taste of Mollusca, 179 Galatea, 15, 328, 336, 453 Galeomma, 175, 453 Galerus, 248, 412; egg-capsules, 125 | Garstang, W., on protective and warn- ing coloration, 73 Gaskoin, on tenacity of life, 38; on egg-laying, 42 Gassies, on hybrid union in snails, 150 Gasteropoda, on classification, 8, 11, 400 f. INDEX Gastrana, 453 Gastrochaena, 457 ; habits, 64 Gastrodonta, 440 Gastropteron, 245, 430 Gaza, 376, 408 Gena, 246, 408 _ Genea, 424 Genotia, 426 Geomalacus, 160, 288, 291, 441; pro- tective coloration, 70 Geomelania, 16, 348, 351, 474 Georgia, 331, 414 Georissa, 318, 410 Geostilbia, 338, 442 Gerontia, 441 Gerstfeldtia, 290 Gibbula, 208 Gibbus, 328-338, 440, 440 Gillia, 415 Gills — see Branchiae Girasia, 301, 304, 440 Glandina, 54, 178, 278, 292 f., 339- 355, 440 ; radula, 231, 232 ; habits, 53 Glands, germ, 134, 140; nidamental, 136 Glassia, 501, 505 Glaucomya, 320, 454 Glaucus, 429, 432 Gleba, 437 Glessula, 301, 309, 310, 333, 442 Glochidium, 147 Glomus, 448 Glossoceras, 394 Glossophora, 7 Glottidia, distribution, 485, 487 Glycimeris, 457 Glyphis, 406 Glyptostoma, 341, 441 Gomphoceras, 394, 395 Gonatus, 391 Goniatites, 397, 398 Goniobasis, 341, 417 Goniodoris, 434; protective colora- tion, 73; radula, 229 Goniomya, 458 Gonostoma, 291, 316, 441 Goniostomus, 442 Grammysia, 459 Grateloupia, 454 Great Eastern and mussels, 116 Greenhouses, slugs in, 35 Green oysters, 108 Gresslya, 458 Growth of shell, 40, 257 Guesteria, 440 Guildfordia, 409 Guivillea, 186, 376, 425 Gulls and Mollusca, 56 Gundlachia, 19, 325, 345, 352, 359, 439 Gymnoglossa, 216, 225, 422 Gymnosomata, 437 ea UE EEE SESE Eee Bot Gyroceras, 247, 395 Gyrotoma, 417 HADRA, 306, 315, 319-325, 322, 447 Hadriania, 423 Haemoglobin, 171 Hainesia, 336, 414 Halia, 366, 426 Haliotinella, 431 Haliotis, 266, 407; and coyote, 57; holes of, 156; osphradium, 195; epipodium, 199; nervous system, 204; radula, 215, 226 Halopsyche, 159, 4388, 438 Haminea, 428, 430; protective colora- tion, 78 Hamites, 399 Hamulina, 399 Hanleyia, 403 Hapalus, 331, 442 Harpa, radula, 425, 216, 221; mutilation, 45 Harpagodes, 418 Harpoceras, 399 Harvella, 454 Hatching of eggs, 45 Hazay, on duration of life, 39; variation in Limnaea, 93 Hearing powers of Mollusca, 196 Heart, in classification, 9 ; action during hibernation, 26 ; and branchiae, 169 Hectocotylus arm, 137 f. Heicion, 405 ; protective coloration, 69 Helcioniscus, 405 Hele, F. M., on Ayalinia, 38; Stenogyra, 34 Helicarion, 309, 316, 325, 3382, ‘440 ; radula, 232 ; habits, 45, 67 Helicidae, radula, 232, 234 Helicina, 305, 306, 316-3827, 338-358, 410; origin, 21; exterminated by cold, 24 Helicophanta, 335, 336, 441, 441 Heligmus, 449 Helix, 441; toothed aperture, 63 ; pro- tective coloration, 70 ; variation, 87 ; carbonic acid, 163; eye, 181, 183; food, 179; smell, 194; jaw, 211; dis- tribution, 285; tenacity of life, 37; breeding, 129 Helix alternata, 340; angulata, 350; aperta, 38, 39, 51, 293; arbustorum, bathing, 23 ; caperata, variation, 89 ; cereolus, 340 ; cicatricosa, 316 ; creni- labris, 45 ; delphinuloides, 297 ; deser- torum, 37, 38, 70, 294; jfidelis, 341; haemastoma, habits, 70; harpa, 287 ; hortensis, 10, 279; pulsations, 26; epiphragm, 28 ; rock-boring, 49; dart, 143; imperator, 347; habits, 45; laciniosa, 297; lactea, 25, 38, 42, 279; lima, 350 ; muscarum, 347; nemoralis, self- on on. 522 38, 180; niciensis, 292; nux denticu- lata, 350; palliata, 340; pisana, 25; habits, 38 ; pomatia, 25, 34, 40; eye, 181; pomum, 3822; pulchella, 279; richmondiana, 322; rosacea, 259; rostrata, 347 ; rota, 314; rufescens, pulsations, 26 ; similaris, 279; sou- verbiana, 3386, 441; strigata, 298; tristis, habits, 49; turricula, 297; Veatchii, 38; Waltont, 304; Wollas- ' tont, 297 ; zonata, 293 ene aspersa, homing, 85; smell, 36 ; duration of life, 39; growth, 40; strength, 46 ; boring rock, 50; varia- tion, 87, 89; eaten, 119; hybrid union, 1380 ; generative organs, 140f., 141; dart-sac, 143 ; pulmonary cham- ber, 160; radula, 217; alimentary canal, 237; monstrosities, 251, 252; growth, 258 ; distribution, 279, 289 Hemiarthrum, 403 Hemicardium, 455 Hemidonax, 453 Hemifusus, 424 Hemipecten, 450 Hemiplecta, 310, 316, 319, 321, 440 Hemisepius, 389 Hemisinus, 357, 417 Hemitoma, 265 Hemitrichia, 314 Hemitrochus, 346-851, 441 Hemphiilia, 245, 341, 441 Hercoceras, 395 Herdman, Prof. W. A., on cerata of Nudibranchs, 71 f.; experiments on taste of Nudibranchs, 72; on Lit- torina rudis, 151 n. Hermaea, 482; protective coloration, 73 Hermaphrodite Mollusca, 134, 140, 145 Hermit-crabs, shells used by, 102 Hero, 432 Heterocardia, 454 Heterodiceras, 455 Heteropoda, 9, 420 f.; foot, 200 Heudeia, 316, 410 Hexabranchus, 434 ° Hibernation, 25, 163 High altitudes, Mollusca living at, 24 Himella, 15 Hindsia, 424 Hindsiella, 453 Hinge area, 493, 498 Hinge, in bivalves, 272 HHinnites, 257, 450 Hipponyx, 248, 412 HHippopus, 456 ITippurites, 455, 456 FHistiopsis, 391 ITistioteuthis, 391 Holcostoma, 417 radula, 228; MOLLUSCA — BRACHIOPODA Holohepatica, 433 Holopella, 411 Holospira, 339, 353, 442 Holostomata, 156 Homalogyra, 413; radula, 223 Homalonyx, 245, 3438-858, 443 Homing powers of Mollusca, 34 Homorus, 330-887, 443 Hoplites, 399 Hoplopteron, 422 Horea, 332 Horiostoma, 409 Hot springs, Mollusca living in, 25 Huronia, 394 Hyalaea, 10, 436 Hyalimax, 245, 305, 806, 338, 443 Hyaline stylet, 240 Hyalinia, 440; pulsations, 26; food, 33; smell, 194; dart, 148; radula, 232, 284; distribution, 287 f., 318, 3840-357 ; H. alliaria, 279; smell, 194; cellaria, 279; Draparnaldi, 33 Hyalocylix, 437 Hyalosagda, 352 . Hybocystis, 305, 309, 414 Hybridism, 129 Hydatina, 430 ; radula, 231 Hydrobia, 325, 332, 415; egg-laying, 128 Hydrocena, 298, 410; radula, 226 Hymenoptera build in dead shells, 102 Hypobranchaea, 434; radula, 230 Hypotrema, 448 Hypselostoma, 248, 302, 305, 314, 442 Hyria, 344, 452 Hystricetla, 297 H. ulvae, IANTHINA, 360, 126, 411; egg-cap- sules, 125; eyes, 186; radula, 224 LIapetella, 385 Iberus, 285-298, 297, 441 Ichthyosarcolites, 456 Idalia, 179, 429, 434 ; radula, 229, 280 Idas, 449 Idiosepion, 389 Illex, 390 Imbricaria, 425; radula, 221 Imperator, 409 Indians of America, use of shells, 100 Infundibulum, 408 Inioteuthis, 389 Ink-sac, 241 Inoceramus, 449 Insects eaten by Mollusca, 32 Insularia, 319, 320 Intestine, 241 Io, 16, 340, 417 Topas, 423 Iphigenia, 15, 453 Travadia, 305, 415 Tridina, 294 TIrus, 297 INDEX 523 Jsanda, 409 Ischnochiton, 403 Isidora, 298, 320-827, 333, 336, 359, 4389 Ismenia, 404 Tsocardia, 269, 451, 451 Isodonta, 453 TIsomeria, 343, 356, 441 Issa, 434 JAMAICIA, 414 Janella, 161, 443; pulmonary orifice, 161 Janellidae, radula, 234; distribution, 321-326 Janus, 432 Japonia, 318 Jaws, 210 Jeanerettia, 346-351, 441 Jeffreys, Dr., on Limnaea, 34; Neptunea, 193 Jeffreysia, 415; radula, 223 Jorunna, protective coloration, 73 Jouannettia, 457 Jullienia, 307, 415 Jumala, 424 on KALIELLA, 301, 304, 510, 314-517, 335, 440 Kalinga, 434 Kashmir, land Mollusca, 280 Katherina, 403 Kelletia, 424 Kellia, 453 Kellyella, 452 Kidneys, 242 King, R. L., on smell in bivalves, 195 Kingena, 506, 508 Kitchen-middens, 104 Koninckella, 505 ; stratigraphical dis- tribution, 507, 508 Koninckina, 505; stratigraphical dis- tribution, 507, 508 Koninckinidae, 501, 505, 508 Kutorgina, 504; stratigraphical distri- bution, 506, 508; embryonic shell, 509 LABIAL palps, 210 Labyrinthus, 342, 353-357, 441; aper- ture, 63 Lacaze-Duthiers on Testacella, 52 f.; on smell in Helix, 194 Lacuna, 413 Lacunopsis, 332 Lagena, 424 Lagochilus, 309, 816-319, 414 Lamellaria, 245, vy 3 ie habits and pro- tective coloration, 74: ; parasitic, 78 ; radula, 223 Lamellidoris, 434; radula, 229, 230, 231 Lampania, 417 Land Mollusca, origin, 11 f. Lanistes, 249, 294, 328, 331, 416 Lankester, Prof. E. Ray, on shell- gland, 1382 ; on haemoglobin, 171 Lantzia, 278, 338, 439 Laoma, 441 Larina, 302, 417 Larvae of Pelecypoda, 7; of insects resembling Mollusca, 67 f. Lasaea, 453 Latia, 19, 326, 439 Latiaxis, 423 Latirus, 424 Latter, O. H., on Glochidium, 147 Layard, E. L., on self-burying Mol- lusca, 41; on sudden appearance of Stenogyra, 47; on Coeliaxis, 49 ; on Rhytida and Aerope, 54 Leda, 447 Leia, 348-351, 442 Leila, 344, 452 Leonia, 414 Lepeta, 405 Lepetella, 405 Lepetidae, radula, 227 Lepidomenia, 404; radula, 229 Leptachatina, 327 Leptaena, 500, 501, 502, 503, 505 ; stratigraphical distribution, 507, 508 Leptaxis, 441 Leptinaria, 357, 358, 442 Leptochiton, 403 Leptoconchus, 75, 423 Leptoloma, 348, 351 Lepton, 453; parasitic, 77; commen- - sal, 80; mantle-edge, 175, 178 Leptoplax, 403 Leptopoma, 316, 319, 338, 414 | Leptoteuthis, 390 Leptothyra, 409 Leroya, 331 Leucochila, 442 Leucochloridium, 61 Leucochroa, 292, 295, 441 Leuconia, 439 Leucotaenia, 335, 359, 441 Leucozonia, 64, 424, 424 Levantina, 295 Libania, 295 Libera, 327, 441; egg-laying, 128 Libitina, 451 Licina, 414 Life, duration of, in snails, 39 Ligament, 271 Liguus, 349, 851, 442 Lima, 178, 179, 450; habits, 63 Limacidae, radula, 232 Limacina, 59, 249, 486, 436 Limapontia, 429, 432; breathing, 152 Limazx, 245, 440; food, 31, 179 ; varia- tion, 86; pulmonary orifice, 160; shell, 175 ; jaw, 211 ; radula, 217 ; distribu- 524 MOLLUSCA — BRACHIOPODA tion, 285, 324; L. agrestis, eats May flies, 31; arborum, slime, 30; food, 31; flavus, food, 33, 36; habits, 35, 36 ; gagates, 279, 358 ; maximus, 32, 161 ; eats raw beef, 82 ; cannibalism, 32; sexual union, 128; smell, 198 f. Limea, 450 Limicolaria, 329-832, 443 Limnaea, 439; self-impregnation, 44 ; development and variation, 84, 92, 93; size affected by volume of water, 94 ; eggs, 124; sexual union, 154; jaw, 211; radula, 217, 235; ZL. auricularia, 24; glutinosa, sudden appearance, 46; Hookeri, 25 ; involuta, 82, 278, 287 ; peregra, 10, 180; burial, 27; food, 34, 37; variation, 85; distribution, 282 ; palustris, distribution, 282; stagnalis, food, 34, 37; variation, 85, 95; cir- cum-oral lobes, 131; generative or- gans, 414; breathing, 161; nervous system, 204 ; distribution, 282 ; trun- catula, parasite, 61; distribution, 282 Limnocardium, 4565 Limnotrochus, 332, 415 Limopsis, 448 Limpet-shaped shells, 244 Limpets as food for birds, 56 ; rats, 57; birds and rats caught by, 57; as bait, 118 Lingula, 464, 467, 468, 471, 472, 473, 475, 477, 478, 487; habits, 483, 484 ; distribution, 485; fossil, 498, 494, 603; stratigraphical distribution, 506, 508, 510, 511 Lingulella, 493, 503; stratigraphical distribution, 506, 508, 511 Lingulepis, 503, 511 Lingulidae, 485, 487, 496, 503, 508 Linnarssonia, 504; stratigraphical dis- tribution, 506, 508 Lintricula, 426 Liobaikalia, 290 Liomesus, 424 Lioplax, 340, 416 Liostoma, 424 Liostracus, 442 Liotia, 408 Liparus, 324, 359, 441 Lissoceras, 399 Lithasia, 340, 417 Lithidion, 414 Lithocardium, 455 Lithodomus, 449 Lithoglyphus, 294, 296, 297, 415 Lithopoma, 409 Lithotis, 302, 443 Litiopa, 30, 361, 415 Littorina, 413 ; living out of water, 20 ; radula, 20,215; habits, 50; protective coloration, 69; egg-laying, 126; hybrid union, 130; monstrosity, 251, 252; ee ee ee operculum, 269 ; erosion, 276 ; L. lit- torea, in America, 374 ; obtusata, gen- erative organs, 135; rudis, 150; Prof. Herdman’s experiments on, 151 n. Littorinida, 415 Lituites, 247, 395 Liver, 259; liver-fluke, 61 Livinhacea, 388, 359, 441 Livona, 408 ; radula, 226; operculum, 268 Lloyd, W. A., on Nassa, 193 Lobiger, 432 Lobites, 397 Loligo, 378-389 ; glands, 186 ; modified arm, 139; eye, 188; radula, 236; club, 381; L. punctata, egg-laying, 127; vulgaris, larva, 133 Loligopsis, 391 Loliguncula, 390 Loliolus, 390 Lomanotus, 433 Lophocercus, 432 Lorica, 403 Lowe, E. J., on growth of shell, 40 Loxonema, 417 Lucapina, 406 Lucapinella, 406 Lucerna, 441 Lucidella, 348-851, 410 Lucina, 270, 452 Lucinopsis, 454 Lung, 151, 160 Lunulicardium, 455 Lutetia, 452 Lutraria, 446, 456 Lychnus, 442 Lyonsia, 458 Lyonsiella, 458 ; branchiae, 168 Lyra, stratigraphical distribution, 507 Lyria, 425 Lyrodesma, 447 Lysinoe, 441 Lytoceras, 398 MAACKTA, 290 Macgillivrayia, 183 Machomya, 458 Maclurea, 410. Macroceramus, 348-858, 442 Macroceras, 440 Macrochilus, 417 Macrochlamys, 296, 299, 301 f£., 310, 316-822, 440 Macrocyclis, 358, 359, 442 Macron, 424 Macroon, 441 Macroscaphites, 247, 399, 399 Macroschisma, 265, 406 Mactra, 271, 446, 454 Macularia, 285, 291, 292 f., 447 Magas, 506; stratigraphical distribu- tion, 507, 508 ett INDEX Magellania, 500 Magilus, 75, 423 Mainwaringia, 302 Malaptera, 418 Malea, 419 Malletia, 447 Malleus, 449 Mangilia, 426 Mantle, 172 f., 173; lobes of, 177 Margarita, 408 ; radula, 225 Marginella, 425; radula, 221 Mariaella, 514, 338, 440 Marionia, 433 Marmorostoma, 409 Marrat, F. P., views on variation, 82 Marsenia, 135 Marsenina, 411 Martesia, 305, 457 Mastigoteuthis, 390 Mastus, 296, 442 Matheronia, 455 Mathilda, 250, 417 Maugeria, 403 Mazzalina, 424 Megalatractus, 424 Megalodontidae, 451 Megalomastoma, 344, 414 Megalomphalus, 416 Megaspira, 358, 442 Megatebennus, 406 Megerlia, distribution, 486, 487 Meladomus, 249, 328, 331, 416 Melampus, 18, 199, 250, 439, 439 Melanatria, 336 Melania, 276, 417, 417; distribution, 285, 292 f., 316 f., 324, 336 Melaniella, 442 Melaniidae, origin, 17 Melanism in Mollusca, 85 Melanopsis, 417; distribution, 291, 292 f., 323, 326 Melantho, 340, 416 Melapium, 424 Meleagrina, 449 Melia, 348 Melibe, 432 Melongena, 424 ; radula, 220 ; stomach, 238 Merica, 426 Merista, 505, 508 Meroe, 454 Merope, 327 Mesalia, 417 Mesembrinus, 356, 442 Mesodesma, 454 Mesodon, 340, 441 Mesomphix, 340, 440 Mesorhytis, 377 Meta, 423 Metula, 424 Meyeria, 424 Miamira, 434 285, 525 Microcystis, 323, 324, 327, 338, 440 Microgaza, 408 Micromelania, 12, 297 Microphysa, protective habits, 70 Microplax, 403 Micropyrgus, 415 Microvoluta, 425 Middendorfia, 403 Milneria, 451 Mimicry, 66 Minolia, 408 Mitra, 425; radula, 221 Mitrella, 423 Mitreola, 425 Mitrularia, 248, 412 Modiola, 446, 449; habits, 64; genital orifice, 242 Modiolarca, 449 Modiolaria, 449; habits, 78 Modiolopsis, 452 Modulus, 417 Monilia, 408 Monkey devouring oysters, 59 Monoceros, 423 Monocondylaea, 452 Monodacna, 12, 297, 455 Monodonta, 408, 408 ; tentaculae, 178 Monogonopora, 134, 140 Monomerelia, 496, 504 Monopleura, 456 Monotis, 449 Monotocardia, 9, 170, 411 Monstrosities, 250 Montacuta, 452; M. ferruginosa, com- mensal, 80; substriata, parasitic, 77 Mopalia, 403 Moquin-Tandon, on breathing of Lim- naeidae, 162; on smell, 198 f. Moreletia, 440 Morio, 420 Mormus, 356, 442 Moseley, H. N., on eyes of Chiton, 187 f. Moussonia, 327 Mouth, 209 Mucronalia, 422 Mucus, use of, 63 Mulinia, 272 Miilleria, 344, 452 Mumiola, 422 Murchisonia, 265, 407 Murchisoniella, 422 Murex, 423; attacks Arca, 60; use of spines, 64; egg-capsules, 124; eye, 182; radula, 220; shell, 256 Musical sounds, 50 Mussels, cultivation of, 115; as bait, 116 ; poisonous, 117 ; on Great East- ern, 116 Mutela, 294, 328, 331, 336, 452 Mutyca, 425 Mya, 271, 275, 446, 456; stylet, 240; M. arenaria, variation, 84 526 Myacea, 456 Myalina, 449 Mycetopus, 307, 316, 344, 452 Myochama, 458 Myodora, 458 Myophoria, 448 Myopsidae, 389 Myrina, 449 Myristica, 424 Mytilacea, 448 Mytilimeria, 458 Mytilops, 452 Mytilopsis, 14 Mytilus, 258, 449; gill filaments, 166, 285; M. edulis, 14, 165; attached to crabs, 48, 78; pierced by Purpura, 60; Bideford Bridge and, 117; rate of growth, 258; stylet, 240 Myxostoma, 414 NACELLA, 405 Naiadina, 449 Nanina, 278, 800 f., 385, 440 ; radula, 217, 232 Napaeus, 296-299, 316, 442 Naranio, 454 Narica, 412 Nassa, 4238; egg-capsules, 126; sense of smell, 1938 Nassodonta, 423 Nassopsis, 332 Natica, 246, 268, 411; spawn, 126; operculum, 268 Naticopsis, 409 ‘Native’ oysters, 106 Nausitora, 15 Nautiloidea, 393 Nautilus, 254, 392, 395 ; modified arms, 140 ; eye, 183 ; nervous system, 206 ; radula, 236; kidneys, 242 Navicella, 267, 268, 324, 827, 410; origin, 17 Navicula, 358, 442 Navicula (Diatom), cause of greening in oysters, 108 Nectoteuthis, 389 Neda, 431 Nematurella, 12, 297 Nembrotha, 434 Neobolus, 504 Neobuccinum, 424 Neocyclotus, 357, 358 Neomenia, 8, 138, 216, 228, 404, 404; breathing organs, 154; nervous sys- tem, 203 Neothauma, 382 Neotremata, 511 Neptunea, 252, 262, 423 ; egg-capsules, 126 ; capture, 193 ; monstrosity, 251 Nerinea, 417 Nerita, 17, 410; N. polita used as money, 97 MOLLUSCA — BRACHIOPODA . Neritidae, 260, 410; radula, 226 Neritina, 256, 410 ; origin, 16, 17, 21; egg-laying, 128; eye, 181; distribu- tion, 285, 291 f., 324, 327; N. jfluvia- tilis, habitat, 12, 25 Neritoma, 410 Neritopsis, 409; radula, 226; opercu- lum, 269 Nervous system, 201 f. Nesiotis, 357, 442 New Zealanders, use of shells, 99 Nicida, 413 Ninella, 409 Niphonia, 408 Niso, 422 Nitidella, 423 Nodulus, 415 Notarchus, 431 Nothus, 358, 442 Notobranchaea, 438 Notodoris, 434 Notoplax, 403 Novaculina, 305 Nucula, 254, 269, 278, 447 Nuculidae, otocyst, 197; foot, 201 Nuculina, 448 Nudibranchiata, 432; defined, 10 ; pro- tective and warning colours, 71 f.; breathing organs, 159 Nummulina, 295 Nuttallina, 403 OBBA, 311, 315, 441 Obbina, 306, 311, 312, 314, 319 Obeliscus, 442 Obolella, 496, 504; stratigraphical dis- tribution, 506, 508 Obolidae, 496, 504, 508 Obolus, 504, 508; embryonic shell, 509 Ocinebra, 423 Octopodidae, hectocotylised arm, 137, 189, 140 Octopus, 379-386 ; egg-capsules, 127; vision, 184; radula, 236; crop, 238 Ocythoe, 384; hectocotylus, 188 Odontomaria, 407 Odontostomus, 358, 442 Odostomia, 250, 422; parasitic, 78 Oesophagus, 237 Ohola, 434 Oigopsidae, 390 Oldhamina, 506, 508 Oleacina, habits, 55 Oliva, 199, 255, 275, 425, 426 Olivancillaria, 426 Olivella, 260, 267, 426 ; O. biplicata as money, 97 Olivia, 408 Omalaxis, 413 Omalonyx, habitat, 23 Ommastrephes, 6, 378, 390 Ommatophores, 180, 187 INDEX Omphalotropis, 306, 309, 316, 324, 327, 338, 414 Onchidiella, 443 Onchidiidae, 245; radula, 234; anus, 241 Onchidiopsis, 411 Onchidium, 443 ; breathing, 168 ; eyes, 187 Onchidoris, radula, 230 Oniscia, 420 Onoba, 415 Onychia, 390 Onychoteuthis, 390; club, 386 Oocorys, 420 Oopelta, 329. 440 Opeas, 442 Operculum, 267 f. Ophidioceras, 247, 395 Ophileta, 413 Opis, 451 Opisthobranchiata, 427; defined, 9; warning, etc., colours, 71 f.; genera- | tive organs, 144; breathing organs, 158 ; organs of touch, 178; parapodia, 199 ; nervous system, 208 ; radula, 229 Opisthoporus, 266, 300, 314-316, 414 Opisthostoma, 248, 309, 413 Oppelia, 399 Orbicula, 464 Orbiculoidea, 504, 510 Orders of Mollusca, 5-7 Organs of sense, 177 Origin of land Mollusca, 11 f. Ornithochiton, 403 Orphnus, 356, 441 Orpiella, 440 Orthalicus, 342-858, 355, 442; habits, 27 ; variation, 87; jaw, 211; radula, 233, 234 Orthis, 505; stratigraphical distribu- tion, 506, 507, 511 Orthoceras, 394, 394 Orthonota, 457 Orthothetes, 505; stratigraphical dis- tribution, 507, 508 Orygoceras, 247 Osphradium, 194 f. Ostodes, 327 Ostracotheres, 62 Ostrea, 252, 258, 446, 449; intestine, 241 Otina, 18, 439 Otoconcha, 326, 440 Otocysts, 196 f., 197 Otopleura, 422 Otopoma, 331, 338, 414 Otostomus, 353, 442 Ovary, 185 Ovoviviparous genera, 123 Ovula, 419; protective coloration, 70, 75 ; radula, 80, 224 ; used as money, 97 Ovum, development of fertilised, 130 Oxychona, 358 527 Oxygyrus, 422; foot, 200 Oxynoe, 432; radula, 230 Oyster-catchers, shells used by, 102 Oyster, cultivation, 104-109; living out of water, 110; enemies, 110 f.; reproduction, 112 f.; growth, 114, cookery, 114; poisonous oysters, 114; vision, 190 PACHNODUS, 829-835, 441, 442 Pachybathron, 425 Pachychilus, 354 Pachydesma_ crassatelloides, made from, 97 Pachydomidae, 451 Pachydrobia, 307, 415 Pachylabra, 416 Pachyotus, 334, 336, 355, 358, 441 Pachypoma, 409 Pachystyla, 387, 440 Pachytypus, 451 Padollus, 407 Palaearctic region, 284 f. Palaeoneilo, 447 Palaeosolen, 457 — Palaina, 327, £13 Palio, 434 Pallial line and sinus, 270 Pallifera, 340, 440 Palliobranchiata, 464 Paludina, 416; penis, 136; eye, 181; vision, 184; P. vivipara, 24—see also Vivipara Paludomus, 332, 336, 338, 417 Panama, Mollusca of, 3 Panda, 322, 325, 335 Pandora, 458 Papuans, use of shells, 99 Papuina, 309, 319-324, 441 Paramelania, 382 Paramenia, 404 Parasitic worms, 60 f. ; Mollusca, 74 f. Parastarte, 451 Parkinsonia, 398 Parmacella, 245, 291, 294 f., 438 n., 440; radula, 232; shell, 175 Parmacochlea, 322, 326, 440 Parmarion, 309, £40 Parmella, 326, 440 Parmophorus, 406 Parthena, 349-352, 350, 441 Parts of univalve shell, 262; bivalve, 269 Partula, 819-327, 326, 442; radula, 233 Paryphanta, 321, 325, 440 Paryphostoma, 415 Passamaiella, 332 Patella, 405, 464; as food, 56 f.; eye, 182; radula, 214, 215, 227; crop, 238; anus, 241; kidneys, 242 ; shell, 262 ; P. vulgata, veliger, 132; breathing organs, etc., 156, 157 money 528 Patelliform shell in various genera, 19 Paterina, 509, 510, 511 Patinella, radula, 227 Patula, 297, 298, 318-338, 340, 447 Paxillus, 413 Pearl oysters, 100 Pecten, 446, 450, 450 ; organs of touch, 178 ; ocelli, 191 ; flight, 192 ; nervous system, 206; genital orifice, 242; ligament, 271 Pectinodonta, 405; radula, 227 Pectunculus, 448 Pedicularia, 75, 419; radula, 224 Pedinogyra, 319, 322, £442 Pedipes, 18, 199, 489, 439 Pedum, 450 Pelagic Mollusca, 360 Pelecypoda, 7, 445; development, 145 ; generative organs, 145; branchiae, 166-169 ; organs of touch, 178 ; eyes, 189 f.; foot, 201; nervous system, 205 Pella, 338 Pellicula, 352, 442 Peltoceras, 399 Pentadactylus, 423 Peraclis, 436 Pereiraea, 418 Perideris, 328-880, 443 Periodicity in breeding, 129 Periophthalmus, 187 Periostracum, 275 Periploma, 459 Perisphinctes, 399 Perissodonta, 418 Perissolax, 424 Peristernia, 424 Perna, 449; ligament, 271 Pernostrea, 449 Peronaeus, 358, 442 Peronia, 443 Perrieria, 319, 442 Perrinia, 408 Persicula, 425 Persona (= Distortio), 420 Petenia, 353, 440 Petersia, 420 Petraeus, 295, 331, 442 Petricola, 454 Phacellopleura, 403 Phanerophthalmus, 430 Phaneta, 408 Phania, 312, 441 Pharella, 457 Pharus, 457 Pharynx, 210 Phasianella, 409 Phasis, 333 Phenomena of distribution, 362 Philine, 245, 428, 430; protective coloration, 73; radula, 229, 230 Philomycus, 245, 318, 440 Philonexis, 188 MOLLUSCA — BRACHIOPODA Philopotamis, 304, 417 Phoenicobius, 315, £41 Pholadacea, 457 Pholadidea, 457 Pholadomya, 459 Pholas, 245, 274, 447, 457; in fresh water, 15 Phos, 424 Photinula, 408 Phragmophora, 386 Phyllidia, 484; breathing organs, 159 Phyllirrhoe, 360, 428, 433 Phyllobranchus, 432 Phylloceras, 398, 398; suture, 396 Phylloteuthis, 390 Physa, 439; aestivating out of water, 27; spinning threads, 29; sudden appearance, 46; osphradium, 195; nervous system, 205; radula, 235; P. hypnorum, 28, 27 Pileolus, £10 Pileopsis, 76 Piloceras, 394 Pinaxia, 423 Pineria, 442 Pinna, 449; shell, 254 Pinnoctopus, 385 Pinnotheres, 62 Pinoceras, 398 Pirena, 417 Pirenella, 416 Piropsis, 424 Pirula —see Pyrula Pisania, 424 Pisidium, 453; smell, 195 ; ova, 146; P. pusillum, distribution, 282 Pitys, 327 Piacobranchus, 432 Placostylus, 322, 323-325, 359, 442; radula, 233 Placuna, 448; P. placenta used for windows, 101 Placunanomia, 448 Placunopsis, 448 Plagioptycha, 347-351, 441 Plagioptychus, 456 Planaxis, 417 Planispira, 311, 312, 319, 441 Planorbis, 27, 247, 439; monstrosity, 93 ; eye, 181; P. albus, distribution, 282 Platyceras, 76, 412 Platydoris, 434 Platypoda, 411 Platyschisma, 413 Plaxiphora, 403 Plecochilus, 442 Plecotrema, 439 Plectambonites, 505 Plectomya, 459 Plectopylis, 303, 305, 314, 316; aper- ture, 63 oP ENE INDEX Plectostylus, 358, 442 Plectotropis, 305, 306, 310, 311, 314— 318, 441 Plectrophorus, 298 Plesiastarte, 451 Plesiotriton, 420 Pleurobranchaea, 431; jaws, 212 Pleurobranchoidea, 431 Pleurobranchus, 245, 428, 431; warning coloration, 73 ; jaws, 212; radula, 230 Pleurocera, 340, 417 Pleuroceridae, origin, 17 Pleurodonta, 348; aperture, 63 Pleuroleura, 433 Pleuromya, 458 Pleurophorus, 451 Pleurophyllidia, 433 ; breathing organs, 159; radula, 230 Pleuropyrgus, 3857 Pleurotoma, 426, 426; slit, 263, 265 Pleurotomaria, 266, 373, 376, 407, 407; prices given for recent, 122; slit, 156; radula, 226 Plicatula, 450 Pliny the elder, on use of snails, 118, 120 Plocamopherus, 434 Plochelaea, 425 Plutonia, 298, 440 Pneumoderma, 158, 437, 488 Poecilozonites, 352, 440 Poisonous bite of Conus, 65; poison- ous oysters, 114; mussels, 117 Polycera, 434; radula, 230 Polycerella, 434 Polyconites, 456 Polydontes, 346-351, 347, 441 Polygona, 424 Polygyra, 340, 345-353, 441 ; aperture, 63 Polygyratia, 246, 263, 357, 442 Polymita, 346-351, 347, 441 Polyplacophora, 9, 401 f.; radula, 228 Polytremaria, 266, 407 Pomatia, 285, 293, 295, 441 Pomatias, 288, 289, 292 f., 302, 473 Pomatiopsis, 415 Pomaulax, 409 Pompholyz, 250, 341, 439 Ponsonbya, 532 Poromya, 459; branchiae, 168 Porphyrobaphe, 27, 356, 442 Position of Mollusca in Animal King- dom, 4 Potamides, 16, 416 Potamomya, 15 Potamopyrgus, 325, 826, 415 Poterioceratidae, 394 Praecardium, 459 Prasina, 449 Prices given for rare shells, 121 Primitive mollusc, form of, 245; types Of 7 WAT tT 529 Prisogaster, 409 Pristiloma, 341, 440 Proboscidella, 497, 504 Productidae, 497, 500, 504, 508 Productus, 492, 501, 502, 504; strati- graphical distribution, 508 Promachoteuthis, 389 Proneomenia, 404; breathing organs, 154 ; nervous system, 208 ; radula, 229 Prophysaon, 341, 441; habits, 44 Propilidium, 405 Proserpina, 21, 355, 410 Proserpinella, 354, 410 Proserpinidae, relationships, 21 Prosobranchiata, 9, 404 f.; breathing organs, 154 Prosocoelus, 451 Protective coloration, 69 f. ; in snails, 70; in Nudibranchs, 71 f. ; in other Mollusca, 74 Protegulum, 509 Protobranchiata, 447; branchiae, 166 Protoma, 417 Protremata, 511 Provocator, 376, 425 Psammobia, 456 Pseudachatina, 328-330, 443 Pseudedmondia, 452 Pseudobalea, 350 Pseudo-deltidium, 498, 511 Pseudodon, 295, 307, 452 Pseudolamellibranchiata, 167, 449 Pseudoliva, 424 Pseudomelania, 417 Pseudomilax, 296, 440 Pseudomurex, 423 Pseudopartula, 323 Pseudosubulina, 440 Ptenoglossa, 224, 411 Pierinaea, 449 Pteroceras, 256, 262, 418 Piteroctopus, 384 -Pterocyclus, 266, 267, 300, 316, 414; tube, 157 Pterodonta, 418 Pteropoda, 7, 434; breathing organs, 158 ; foot, 200; radula, 230 Pterotrachaea, 421 ; foot, 200; radula, 227 Ptychatractus, 424 Ptychoceras, 399 Ptychodesma, 452 Pugilina, 424 Pulmonata, 10, 22, 151, 185, 438; ori- gin, 17, 19; breathing organs, 160 ; nervous system, 203 Pulsellum, 444 Punctum, 441 Puncturella, 265, 406 Pupa, 289, 296, 325-357, 442; P. cine- rea, hybrid union, 129 Pupidae, radula, 233 2M 530 Pupilla, 442 Pupillaea, 406 Pupina, 157, 266, 309, 318-327, 414 Pupinella, 318, 414 Purpura, 423; operculum, 269; ero- sion, 276 ; P. coronata, 367 ; lapillus, feeding on Mytilus, 60; on oysters, 111; protective coloration, 69; vari- ation, 90 ; egg-capsules, 124; time of breeding, 129; distribution, 363 n. Purpuroidea, 423 Pusionella, 426 Pygocardia, 451 Pygope, 497 Pyramidella, 422 Pyramidellidae, 262 Pyrazus, 50, 416 Pyrgina, 330 Pyrgula, 415 Pyrochilus, 441 Pyrolofusus, 423 Pyrula (= Pirula), 419, 420; spawn, 125 ; operculum, 269 Pythina, 453 QUENSTEDTIA, 456 Quoyia, 260, 417 RACHIGLOSSA, 220, 422; eggs, 124 Rachis, 329-835, 441, 442 Radiolites, 456 Radius, 419 Radsia, 403 Radula, 218 f.; of Littorina, 20; of Cyclophorus, 21;. of parasitic Mol- lusca, 79 Raéta, 454 Ranella, 256, 420 Range of distribution, 362 f. Rangia, 15, 453 Ranularia, 420 Rapa, 423 Rapana, 423 Raphaulus, 305, 309 Rathowisia, 316, 440 Rats devouring Mollusca, 57 Realia, 316, 327, 414 Recluzia, 411 Rectum, 241 Registoma, 414 Relationship of Mollusca to other groups, 5 Renssoellaria, 512 Reproductive activity of oyster, 112 ; system in Mollusca, 1238, 134 f. FRequienia, 269, 455, 455 Respiration, 150 f. Retzia, 508 Revoilia, 331, 414 Reymondia, 332 Rhabdoceras, 398 Rhagada, 311, 324 MOLLUSCA — BRACHIOPODA Rhenea, 325, 440 Rhinobolus, 504 Ehiostoma, 247, 266, 309, 414 Rhipidoglossa, 225, 405 Rhizochilus, 75, 423 Rhodea, 356, 441 Rhodina, 307, 310, 442 Rhynchonella, 466, 470, 471, 472, 474, 483, 487; distribution, 487 ; fossil, 492, 497, 499, 505; stratigraphical distribution, 506, 507, 508, 511 Rhynchonellidae, 487, 501, 505 ; strati- graphical distribution, 507, 508, 511 FRhysota, 67, 310, 314, 316, 319, 440 Fhytida, 319-326, 333, 359, 440 ; habits, 64; radula, 232 Rillya, 442 Rimella, 418 Rimula, 265, 406 Ringicula, 430; radula, 230 Risella, 413 Rissoa, 415 Rissoina, 415 Robillardia, 77 Rochebrunia, 381, 414 Rock-boring snails, 49 Rolleia, 349 Rossia, 389 Rostellaria, 418 Rudistae, 456 Rumina, 260, 442 Runcina, 431 ; protective coloration, 73 SABATIA, 430 Sactoceras, 394 Sagda, 348-351, 441 Sageceras, 398 Salasiella, 353, 440 Salivary glands, 237 “Sandford, on strength of Helix, 45 Sandwich islanders, use of shells, 99 Sanguinolaria, 456 Sarepta, 447 Sarmaticus, 409 Satsuma, 314, 316, 441 Saxicava, 447, 457 Saxidomus arata, money made from, 97 Scalaria, 247, 263, 411; radula, 224 Scaldia, 452 Scalenostoma, 422 Scaliola, 415 Scaphander, 428, 429, 430; 231; gizzard, 238 Scaphites, 399, 399 Scaphopoda, 444; defined, 6; breath- ing organs, 160; nervous system, 205; radula, 236 Scaphula, 14, 305, 448 Scarabus, 18, 278, 489, 439 Scharff, R., on food of slugs, 81; on protective coloration in slugs, 70 Schasichetla, 347, 351, 354, 410 radula, J : « INDEX Schismope, 266, 407 Schizochiton, 187, 402, 403 Schizodus, 448 Schizoglossa, 325, 440 Schizoplax, 403 Schizostoma, 413 Schloenbacia, 398 Scintilla, 175, 453 Scissurella, 265, 407 ; edule 226 Sclerochiton, 403 Scrobicularia, 15, 164, 453 ; 164 Sculptaria, 333. Scurria, 405 Scutalus, 556, 442 Scutellastra, 405. Scutus, 245, 406, 406 Scyllaea, 433 ; jaws, 212 ; stomach, 239 Segmentina, 320 Selenites, 339, 341, 440 Selenitidae, radula, 231 Selenochlamys, 296 Self-fertilisation, 42-44 Semele, 453 - Semicassis, 420 Semper, K., on habits of Limnaea, 34; of Helicarion, 45, 67; on mimicry, 67; on parasitic Hulima, 79; on de- velopment of Limnaea, 84, 94; on sexual maturity in snails, 129; on Onchidium, 187 Sepia, 381, 385-887, 389 ; egg-capsules, 127; glands, 136; jaws, 214; radula, 236 ; alimentary canal, 238 ; ; ink-sac, 241 ; hectocotylus, 389 Sepiadarium, 889 Sepiella, 389 Sepiola, 389; glands, 186; radula, 236 Sepioloidea, 389 Sepiophora, 388 Sepioteuthis, 390; hectocotylus, 1389 Septaria, 337, 338, 410 Septibranchiata, 145, 167, 459; bran- chiae, 166 Septifer, 274, 449 Sequenzia, 420 Sergius Orata, 104 Serrifusus, 424 — Sesara, 305, 440 Sex, differences of, 133 Shell, 244 f. ; internal, 174; bivalve, 445 Shell-gland, primitive, 132 Shells as money, 96 f. ; as ornament, etc., 98 f.; various uses of, 98 f.; Bee given for rare, 121 ; sinistral, 2 Shores of N. Asia, no littoral fauna, 2 Showers of shells, 47 Sigaretus, 186, 245, 267, 411; foot, 198 Sight, 180 Silenia, 459; branchiae, 168 ee siphons, shape of 531 | Silia, 425 Siliqua, 274, 457 Siliquaria, 248, 418 Simnia, 419 Simpulopsis, 345, 350, 442 Simpulum, 420 Simroth, on recent forms of Helix, 22 ; on food of slugs, 31; on crawling of Felix, 45 Singular habitat, 48 Sinistral shells, 249 Sinistralia, 424 - Sinusigera, 133 Sipho, 424 Siphonalia, 424 Siphonaria, 18, 437 ; classification, 19 ; breathing organs, 151, 152 Siphonarioidea, 431 Siphonodentalium, 444 Siphonostomata, 156 Siphonotreta, 493, 496, 504; strati- graphical distribution, 507, 508 Siphons, 173; in burrowing genera, 165; branchial, 155 Sistrum, 75, 423; radula of S. spec- trum, 79, 222 Sitala, 301, 304, 310, 314-319, 333, 440 Skargard, Mollusca of the, 13 Skenea, 415 Skenidium, 505, 508 Slit, in Gasteropoda, 265, 406 Slugs, habits and food of, 30 f. ; bite hand of captor, 33 ; in bee-hives, 36 ; in greenhouses, 36; protective col- oration, 70; eaten in England,. 120 Smaragdia, 21 Smaragdinella, 430 Smell, sense of, 192 Smith, W. Anderson, quoted, 98, 111, 114, 191 Snails as barometers, 50; plants fer- tilised by, 102; cultivation for food, 118 f. ; used for cream, 119 ; as medi- cine, 120 ; banned by the Church, 121 Solariella, 408; radula, 225 Solarium, 264, 412, 418; radula, 224 Solaropsis, 343, 353-357, 442 Solecurtus, 165, 457 Solen, 171, 446, 457; habits, 45 Solenaia, 452 Solenomya, 275, 448 Solenotellina, 456 Solomon islanders, use of shells, 98 Somatogyrus, 415 Sophina, 305 Spallanzani, experiments on Helix, 163 Spat, fall of, 113 Spatha, 294, 331, 3386, 452 Spekia, 333 Spermatophore, in Coubalopeay 137; in Helix, 142 a vision, 190; 532 |g Spermatozoa, forms of, 136 Sphaerium, 453 Sphenia, 456 Sphenodiscus, 398 Sphyradium, 442 Spines, use of, 64 Spiraculum, 266, 414 Spiraxis, 442 Spirialis, 249 Spirifera, 468, 501, 505 ; stratigraphical distribution, 507, 508, 511, 512 Spiriferidae, 501, 505, 508 Spiriferina, stratigraphical tion, 507, 508 Spirobranchiata, 464 Spirotropis, 426; radula, 218, 219 Spirula, 247, 386, 887, 388 Spirulirostra, 380, 386, 388 Spondylium, 500 Spondylus, 257, 446, 450, 450; ocelli, 191; genital orifice, 242 Spongiobranchaea, .437 Spongtochiton, 403 Sportella, 453 Starfish eat oysters, 110 Stearns, R. E.C., on tenacity of life, 38 Stegodera, 306 Stenochisma, 505; stratigraphical dis- tribution, 507, 508 Stenogyra, 324, 442; S. decollata, 279 ; food, 34; smell, 194 ; Goodallii, 279 ; octona, sudden appearance, 47 Stenogyridae, radula, 234 Stenopus, 440; habits, 45 Stenothyra, 415 Stenotis, 416 Stenotrema, 340, 441 Stephanoceras, 399 Stepsanoda, 358 Stilifer, 76, 77, 79, 422 Stiliferina, 76, 422 Stiliger, 432 Stilina, 76 Stoastoma, 348-351, 410 Stoloteuthis, 389 Stomach, 239 Stomatella, 408 Stomatia, 408 Stomatodon, 302, 417 Strebelia, 353, 440 Strength of Helix, 45 Strephobasis, 417 Strepsidura, 424 Streptaulus, 414 Streptaxis, 302, 306, 309, 314-381, 343, 357-359, 440 ; variation, 87 Streptoneura, 203, 404 Streptosiphon, 424 Streptostele, 329, 338, 440 Streptostyla, 343-355, 858, 440 Stricklandia, 505; stratigraphical dis- tribution, 507, 508 distribu- MOLLUSCA — BRACHIOPODA Strigatella, 425 Stringocephalidae, 506, 508 Stringocephalus, 492, 497, 498, 500, 501, 506; stratigraphical distribu- tion, 507, 508 Strobila, 340, 345-353 Strobilops, 442 Strombidae, habits, 64; penis, 186 Strombina, 423 Strombus, 69, 200, 252, 418; mimick- ing Conus, 69 ; operculum, 78, 269 ; pearls from, 101: - metapodium, 199; stomach, 239 Str ophalosia, 504; stratigraphical dis- tribution, 507, 508 | Stropheodonta, 497, 505, 508 _ Strophia, 343-355, 442; S. nana, 278 Strophochilus, 358, 441 Strophomena, 499, 505 ; stratigraphical distribution, 507, 508 Strophomenidae, 500, 505, 508 Strophostoma, 248, 414 Structure of shell, 252 : Struthiolaria, 99, 418; radula, 216 . Styliola, 437 Stylodonta, 339, 441 Stylommatophora, 11, 181, 439 ; origin, 19 Subemarginula, 406 Submytilacea, 451 Subularia, 422 Subulina, 332, 352, 442 Subulites, 420 Succinea, 825, 327, 358, 433 ; jaw, 211; S. putris, parasite of, 61 Succineidae, 443 ; radula, 234 Sudden appearance of Mollusca, 46 — Suessia, stratigraphical distribution, 507 Sulphuric acid, 237 Surcula, 426 Sycotypus, 424 Synaptocochlea, 408 Syndosmya, 453 Syringothyris, 500, 508 Syrnola, 422 Syrnolopis, 3382, 388 Systrophia, 356, 357 TACHEA, 441 Taenioglossa, 223, 411 Taheitia, 414 Talona, 457 Tanalia, 304, 417 Tancredia, 453 Tanganyicia, 332, 415 Tanganyika, L., fauna of, 12 Tanysiphon, 454 Taonius, 391, 391 Tapes, 454 Taste, 179 Tebennophorus, 143, 340, 440 ae INDEX Tectarius, 413 Tectibranchiata, 10, 429 Tectura, 305, 405 Tectus, 408 Teeth in aperture of the shell, 63 Teinostoma. 247, 408 Teinotis, 407 Telescopium, 252, 416 Tellina, 446, 453, 453; T. balthica, variation, 84 Tellinacea, 453 Telotremata, 511 Tenacity of life, 37 Tenison-Woods, on red blood, 171; on shell-eyes, 189 Tennent, Sir J. E., on musical sounds produced by Mollusca, 50 Tennentia, 304, 314, 338, 440 Terebellum, 418; jamping powers, 64 Terebra, 246, 263, 426, 426; radula, 219 Terebratella, 468, 487; distribution, 486 ; fossil, 506 ; stratigraphical dis- tribution, 508 Terebratula, 467, 468, 487; size, 484; distribution, 485, 486; fossil, 492, 499, 506; stratigraphical distribu- tion, 506, 507, 508 Terebratulidae, 487; fossil, 500, 505, 506 ; stratigraphical distribution, 507, 508 Terebratulina, 466, 479, 487; larva, 482; distribution, 486; fossil, 506; stratigraphical distribution, 508; form of shell, 510 Teredina, 457 Teredo, 262,457, 458 ; nervous system, 206 ; intestine, 241 Tergipes, 432 Terquemia, 450 Testacella, 22, 52, 440 ; habits, etc., 49, 51 f.; pulmonary orifice, 160; eyes, 186; radula, 231; anus, 241 Testicardines, 466, 487; muscles, 476 ; fossil, 497, 504; external characters, 497 ; internal characters, 499 ; attach- ment of muscles, 501 ; stratigraphical distribution, 508 Testis, 135 Tethyidae, 216 Tethys, 432 Tetrabranchiata, 391 f. Thala, 425 Thalassia, 319 Thalotia, 408 Thapsia, 329 Thaumasia, 349, 442 Thaumastus, 356, 442 Thecacera, 434; radula, 229 Thecidiidae, 487 ; fossil, 501, 506, 508 Thecidium, 475, 479, 480, 483, 487; fossil, 506, 508 ; 533 Thecosomata, 435 Thelidomus, 346-351, 350, 441 Theora, 453 Therasia, 441 Thersites (Helicidae), 322, 525 Thersites (Fasciolariidae), 424 Thetis, 454 Thracia, 245, 459 Thread-spinning, 29 Thridachia, 432 Thyca, 76, 79 Thyrophorella, 330, 440 Thysanoteuthis, 390 Tiedemannia, veliger, 182 Tiphobia, 332, 338, 417 Titicaca, L., Mollusca of, 25 Todarodes, 390 Tomichia, 414 Tomigerus, 334, 356, 358, 442 Tomocyclus, 354 Tomostele, 330, 440 Tonicella, 403 .- Tonicia, 403 ; eyes, 188 Torellia, 411 Torinia, 413 ; radula, 224; operculum, 269 Tornatellina, 278, 319, 323-827, 338, 358, 443 Tornatina, 250, 430 Torquilla, 442 Toucasia, 455 Touch, sense of, 177 Toxoglossa, 218, 426 Trachia, 314 Trachyceras, 397 Trachydermon, 403 Trachyteuthis, 389 Tralia, 439 Transovula, £19 Trematis, 492, 493, 504; stratigraphi- cal distribution, 507, 508 Trematonotus, 407 Tremoctopus, 384£; radula, 286; hec- tocotylus, 137 Trevelyana, 434 Trichia, 316 Trichotropis, 275, 411 Tricula, 302 Tridacna, 278, 455 Triforis, 416; radula, 224 Trigonellites, 397 Trigonia, 15, 254, 269, 448; jumping “powers, 65 ; distribution, 370 Trigonochlamys, 296, 440 Trigonostoma, 426 Trimerella, 495, 504, 508, 511 Trimerellidae, 493, 494, 496, 504; strat- igraphical distribution, 507, 508 Trinacria, 448 Triodopsis, 340, 441 Triopa, 434 Triopella, 434 534 MOLLUSCA — BRACHIOPODA Triopha, 484 Tritaxeopus, 385 Triton, 256, 275, 420; jaws, 212 Tritonia, 433; protective coloration, 71 Tritonidea, 424 Trivia, 419 Trochidae, egg-capsules, 125 Trochiscus, 408 Trochita, 248, 412 Trochoceras, 395 Trocholites, 395 Trochomorpha, 306, 321, 324, 327, 333, 441 Trochonanina, 331, 440 Trochosphere, 5, 180 Trochotoma, 266, 407 Trochus, 263, 408 ; eye, 182; stomach, 239 Trophon, 423 Tropical beach, Mollusca of a, 3 Tropidophora, 414 Tropites, 397 Troschelia, 424 Truncaria, 423 Truncatella, 260, 414 Tryblidium, 405 Trypanostoma, 340 Trypho of Lampsacus, prayer against snails, 121 Tubed operculates, 157, 266, 300, 307, 309 Tudicla, 424 Tudora, 291, 349, 351, 414 Tugonia, 456 Tulotoma, 340, 416 Turbinella, 100, 262, 264, 424, 424 Turbo, 409; eye, 182; osphradium, 195 ; operculum, 268 Turbonilla, 250, 382, 422 Turcica, 408 Turricula, 425; radula, 221 Turrilites, 399, 399 Turritella, 252, 417; radula, 215, 224 Tyleria, 459 Tylodina, 431 Tylopoma, 416 Tympanotonus, 416 Tyndaria, 447 Typhis, 428 ULTRA-DEXTRAL Shells, 250 Umbonella, 409 Umbonium, 409 . Umbrella, 10, 431; radula, 217, 230 Uncites, 505; stratigraphical distribu- tion, 507, 508 Underground snails, 48 Ungulina, 452 Unicardium, 452 Unio, 452; shell, 254, 259, 278, 341; variation, 92 Union of Limaz, 128 Unionidae, origin of, 15; eaten by rats, 57; larvae, 146 Urocyclus, 331, 440 Urosalpinx, 423 Utriculus, 430 Uvanilla, 409 VAGINULA, 245, 319, 348, 352, 443 Vaginulidae, radula, 234; anus, 241 Valletia, 456 _ Vallonia, 441 Valvata, 138, 416; branchia, 159 Valves of Chitonidae, 401 f. Vanganella, 454 Variation, 82 f. Varicella, 346, 348 Velates, 260, 410 Velifera, 353, 440 Veliger stage, 131; mistaken for per- fect form, 133 Velorita, 302, 453 Velum, 1381 Velutina, 275, 411; radula, 223 Veneracea, 454 Venericardia, 451 Venerupis, 454 Veniella, 451 Venilicardia, 451 Venus, 270, 271, 446, 454; V. merce-__ naria, 97, 374 Verania, 391 Vermetus, 247, 418 ; sani 223 Veronicella, 443 Verticordia, 458 Vertigo, 327, 442; V. arctica, 287 Veuilla, 423 Vibex, 417 Vitrella, 289 Vitrina, 22, 296 f., 332, 440; hardy habits, 24 ; jumping powers, 65; shell, 175; radula, 217 Vitrinella, 408 Vitriniconus, 314, 440 Vitrinoidea, 314, 440 Vitrinozonites, 340, 440 Vitularia, 423 Vivipara, 324, 348, 416 Volume of water, effect in producing variation, 94 Voluta, 267, 425, 425; spawn, 125; radula, 217, 221; distribution, 370; prices given for rare, 122 Volutaxis, 348 Volutharpa, 267, 424 Volutolithes, 425 Volutolyria, 425; radula, 222 Volutomitra, 425; radula, 221 Volutopsis, 423 Volwaria, 429 Volvatella, 430 Volvula, 430 | Vulsella, 76, 446, 449 INDEX WALDHEIMIA, 464, 467, 468, 473, 474, 487; size, 484; distribution, 486; fossil, 500, 501, 502, 506, 508 Walton and mussel cultivation, 115 Wampum, 97 Warner, R., quoted, 37 Warning coloration, 71 f. West Coast, South America, melanism of shells occurring on, 85 Whelks, use of, 118 Whitneya, 424 Whitstable, oyster-parks at, 106, 112 Willem, V., on vision of Mollusca, 185 Wollaston, T. V., quoted, 32 Wood, Rev. J. G., on starfish eating oysters, 111 Woodia, 451 Woodward, S. P., on tenacity of life, 38; Dr., on the same, 38 Wotton, F. W., on egg-laying of Arion, 42 Wright, Bryce, on tenacity of life, 38 529 XENOPHORA, 412; habits, 64 XAXenopoma, 346, 351 XAerophila, 285, 296, 441 rr 310, 319, 321, 440; mimicry by, 66 f. Aylophaga, 457 YETUS, 425 Yoldia, 447; genital orifice, 242 ZAGRABICA, 297 Zebrina, 285, 296, 442 Zeidora, 406 Zidona, 425 Zittelia, 420 Zones of depth, 361 Zonites, 275, 440; food, 33; radula, 232 ; distribution, 294, 296, 340 Zospeum, 187, 442 Zygobranchiata, 154, 406 END OF VOL. III. Fa y - e ‘ t wey Pes MACMILLAN & CO.’S PUBLICATIONS ON Mee RAL Wis] ORY, ETC. ADLER (H).— Alternating Generations. A Biological Study of Oak Galls and Gall Flies). By HERMANN ADLER, M.D., Schleswig. Translated and edited by CHARLES R. StraTON, F.R.C.S. Ed, F.E.S. $3.25. BADENOCH (L. N.).—The Romance of the Insect World. By L. N. BADENOCH. With Illustrations by MARGARET J. D. BADENOCH and others. 2d Edition. Gilt top. $1.25. BALFOUR.—A Treatise on Comparative Embryology. By. F.M.BALFour, M.A., F.R.S., Fellow and Lecturer of Trinity College, Cambridge. With Illustrations. | Second Edition, reprinted without alteration from the First Edition. In 2vols. 8vo. Vol. I., $4.50; Vol. II., $5.25. BATESON (W.).— Materials for the Study of Variation, treated with especial Regard to Discontinuity in the Origin of Species. By WILLIAM BATESON, M.A.. Fellow of St. John’s College, Cambridge. With many cuts. 8vo. $6.50. BEDDARD (Ff. E.).— Animal Colouration. With 4 Coloured Plates, and Woodcuts in the Text. By FRANK EvERS BEDDARD, M.A., F.R.S., Prosector to the Zodlogical Society of London and Lecturer on Biology at Guy’s Hospital. 8vo. $3.50. A Monograph, Structural and Systematic, of the Order Oligocheta. Large Post 8vo. Halfcloth. 800pp. ust ready. CAMBRIDGE NATURAL HISTORY (The). Edited by J. W. CLark, M.A., S. F. HARMER, M.A., and A. E. SHIPLEY, M.A. . Medium 8vo. This series, which will be complete in ten volumes, fully illustrated, and covering the Natural History of Invertebrate and Vertebrate Animals, is intended, in the first instance, for those who have not had any special scientific training, but an attempt will be made to combine popular treatment and popular language with the most modern results of scientific research. - The following volumes are likely to appear in the course of 1895 : Molluscs. By Rev. A. H. Cooke, M.A. ust ready. Insects. By DAVID SHARP, M.A., F.R.S. 2 vols. Birds. By A. H. Evans, M.A BOOKS ‘ON NATURAL: HISTORY, ETC: CLAUS. —Hlementary Text-Book of Zodlogy. By Dr. C. CLaus. Trans- lated and edited by ADAM SEDGWICK, M.A., with the assistance of F. G. HEATHCOTE, B.A. Part I., General Part and Special Part: Protozoa to Insecta. Part II., Special Part : Mollusca to Man. With 706 Woodcuts. 2vols. 8vo. $8.00. ECKER. — The Anatomy of the Frog. By ALEXANDER ECKER. Translated with numerous Annotations and Additions, by G. HAsLAmM, M.D., and illustrated with 250 Wood Engravings and 11 Coloured Figures. $8vo. $5.25. EHIMER.— Organic Evolution as the Result of the Inheritance of Ac- quired Characters, according to the Laws of Organic Growth. By Dr. G. H. THEopoR EIMER, Professor of Zoology and Comparative Anatomy in Tiibingen. Translated by T. J. CuNNINGHAM, M.A., F.R.S.E., late Fellow of University College, Oxford. Part I., with 6 Figures in the Text. 8vo. $3.25. FLOWER. — Mammals, Living and Extinct. By WILLIAM HENRY FLOWER, C.B., F.R.S., D.C.L., Director of the Natural History Departments, British Museum, and RICHARD LYDECKER, B.A. 8vo. Cloth. Illustrated with 357 Figures. $6.00. FOWLER (A. WarDE). — Tales of the Birds. With Illustrations. New and cheaper Edition. $1.25. A Year with the Birds. With Illustrations. $1.25. GUNTHER (AzeErt C. L. G.). — An Introduction to the Study of Fishes. With Index. Illustrated with 320 Wood Engravings. 8vo. $6.00. HERTWIG (0O.).—Text-book of the Embryology of Man and Mammals. By Dr. Oscar HErRTWIG. Translated from the Third German Edition by EpwARD L. Mark, Hersey Professor of Anatomy in Harvard University. With 330 Figures in the Text and two Lithographic Plates. 8vo. $5.25. The Cell: its Anatomy and Physiology. By Dr. OscAR HERTWIG, Professor in the University of Berlin. Translated by HENRY JOHNSTONE CAMPBELL, M.D. With 168 Illustrations. 7 the Press. HUXLEY and MARTIN.—A Course of Hlementary Instruction in Practical Biology. By T. H. Hux.ey, LL.D., F.R.S., assisted by H. N. Martin, M.A., M.D., D.Sc., F.R.S. Revised Edition, Extended, and Edited by G. B. Howes and D. H. Scotr. With a Preface by Professor HUXLEY. I2mo. $2.60. KIRBY (W.F.).— Elementary Text-Book of Entomology. 2d Edition, Revised. With 87 Plates. 8vo. $3.00. LANG. —Text-Book of Comparative Anatomy. By Dr. ARNOLD LANG, Professor of Zodlogy in the University of Zurich; Formerly Ritter Professor of Phylogeny in the University of Jena. With a Preface to the English Translation by Professor Dr. ERNST HAECKEL, F.R.S., Director of the Zo6- logical Institute in Jena. Translated into English by HENRY M. BERNARD., 2 BOOKS ON NATURAL AISTORY, ETC. M.A. (Cantab.) and MATILDA BERNARD. Part I. Complete with Index and 383 Illustrations. 8vo. $5.50. Professor Lang has here successfully carried out the very difficult task of selecting the most important results from the bewildering mass of new material afforded by the extensive researches of the last decades, and of combining them with great judgment. Besides this he has, more than any former writer, utilized the comparative history of development in explaining the structure of the animal body, and has endeavored always to give the phylogenetic significance of ontogenetic facts. —From Professor Haeckel’s Preface. LUBBOCK (Sir J.).— On the Origin and Metamorphoses of Insects. With Illustrations. Mature Series. $1.00. MIVART.—Lessons in Hlementary Anatomy. By St. GEORGE Mivart, F.R.S., Lecturer in Comparative Anatomy at St. Mary’s Hospital. With up- wards of 400 Illustrations. 1I16mo. $1.75. PARKER. —A Course of Instruction in Zodtomy (Vertebrata). By T. JEFFERY PARKER. With seventy-four Illustrations. I2mo. $2.25. WALLACE. — Works by Alfred Russel Wallace, LL.D., F.L.S. Darwinism. Being a Systematic Exposition of the Theory of Natural Selection, with Some of its Applications. With numerous Illustrations. $1.75. “ The present work contains the conclusions upon this great subject of thirty years of thought and observation. ... A contribution of the first importance to the literature of the subject. At the same time it would be difficult to find a book more entertaining to the general reader. He writes with the sincerity and easy mastery which comes of fulness of knowledge. There can be no more interesting guide in that great wonderland of science in which he has been so long one of the chief discoverers.’’ — Vew York Times. The Malay Archipelago ; The’ Land of the Orang Utan and the Bird of Paradise. A Narrative of Travel. With Studies of Man and Nature. With Illustrations. Ninth Edition. 1I2mo. $1.75. Contributions to the Theory of Natural Selection; and Tropical Nature and Other Essays. New edition. In one volume. 12mo. $1.75- Island Life; or, The Phenomena and Causes of Insular Faunas and Floras. Including Revision and Attempted Solution of the Problem of Geo- logical Climates. With Illustrations and Maps. New and cheaper Edition. I2mo. $1.75. WIEDERSHEIM.— Elements of the Comparative Anatomy of Verte- brates. Adapted from the German of ROBERT WIEDERSHEIM. By W. NEWTON PARKER. With Additions. Illustrated with 270 Woodcuts. 8vo. $3.00. WHEISMANN.W— Essays upon Heredity and Kindred Biological Prob- lems. By Dr. AUGUST WEISMANN, Professor in the University of Freiburg in Breisgau. Edited by Epwarp B. PouLTon, M.A., F.R.S., SELMAR SCHONLAND, and ARTHUR E. SHIPLEY. I2mo. $2.00. MACMILLAN & CO., 66 FIFTH AVENUE, NEW YORK. 3 Columbia University Biological Series. EDITED BY HENRY FAIRFIELD OSBORN, Da Costa Professor of Biology in Columbia College. The first two volumes of this sertes were published in October; the third will be ready in April, and the fourth in October, 1895. . From the Greeks to Darwin. Buckram. §8vo. Il. Amphioxus and the Ancestry of the Vertebrates. Buckram. 8vo. Ill. Fishes, Living and Fossil. (In Preparation.) IV. The Cell in Development and Inheritance, (In Preparation.) OPINIONS OF THE PRESS. ‘The Columbia University of New York has decided to issue a series of small volumes on Biology, under the editorship of Dr. Osborn, the Da Costa Professor of Biology. It is not to be a library of elementary text-books in the ordinary sense of the term, but to consist chiefly of works dealing with certain fundamental problems which will concern students who have passed beyond preliminaries.’’ — Vatural Sctence (London). “Tf the other volumes in course of preparation by the professors in biology of Columbia University are up to the high standard of the present one (Amphioxus and the Ancestry of the Vertebrates), that institution is to be congratulated upon the enterprise of those who initiated the project.” — The American Naturalist (Philadelphia). ““The ‘Columbia University Biological Series’ is a new scientific publishing venture undertaken by Messrs. Macmillan & Co., under the general editorial supervision of Henry Fairfield Osborn. Numbers 1 and 2 of the series reach us, Prom the Greeks to Darwin, by H. F. Osborn, and Am~phitoxus and the Ancestry of the Vertebrates, by Arthur Willey. Judging from these volumes, the Columbia Biological Series will be of the utmost interest to students.” — Philadelphia Evening Telegram. ‘* The ‘ Columbia University Biological Series,’ as inaugurated by the Macmillans, opens with a general review of the rise and progress of the evolution idea, from its first rudimentary pore peor by the Greek mind to the full development wrought out by Darwin.” — Milwaukee entinel. MACMILLAN & CO., PUBLISHERS, 66 FIFTH AVENUE, - - - - - NEWegaee 4 : [Ss ~