wee 457° a+ < . Ys we et @ © ee ‘* Af Sart see ee : Yeeeee: 4 TE eee ? : f wre re eréte tree wees eae ye Pes oe . z ; : : eA ee ederet . Ath da ° . o 1." + eee e t be et 7 a kA Se? satasasatates oe 'e eee hey “ee ee lee re se 2.2.68 ee i2¢€ ere ee he Te Vee ee ee (2) & ele s sf 7 te © 2 ee ee ee a ae eapee ve eee eee vere Ces *- ree . Te ereren arate et Ore es = he she oes t_ 4 ee a ; / ees eee tone : +e = 4 ean cien Pewaeceaet ee Peet rres Fe ah ee tk ke PoC MCSE LP eae ake teak Meld ath) i oe See te ee he PWS eee : C. eo oe. (se Sa Raat Hast teraierst see BISBEE Te gbgysasaeysosy ait ax : : ene ; > . . 7 efeleie eset, . Ve ee ye Mvid i * kaw & fa + | LIBRARY FE THOMPSON BUILDING CONIC tet 1OHM/Taw - * 4 | t - 4 i i ‘ PP ; a x » = 7 j 2% = : i — eee es a : = 7 ? PA z . - * - 7 ; a : 5 ’ t a ; WV . : » i , 4 i [ THE CAMBRIDGE NATURAL HISTORY EDITED BY S. F. HARMER, M.A., Fellow of King’s College, Cambridge ; Super- intendent of the University Museum of Zoology AND A. E. SHIPLEY, M.A., Fellow of Christ’s College, Cambridge; University Lecturer on the Morphology of Invertebrates VOLUME III ee feo eee ee | Ee London: Macmillan &C° 15 W.Long: 0.E.Long: lp = b 7 aia cies | Map to illustrate THE GEOGRAPHICAL DISTRIBUTION of the LAND OPERCULATE MOLLUSCA eet undicate the number of known sp: a MOLEUSCS By the Rev. A. H. Cooke, M.A., Fellow and Tutor) of _ King’s College, Cambridge bRAGHIOPODS (RECENT) By A. E. Saiptey, M.A., Fellow of Christ’s College, Cambridge | BRACHIOPODS (FOSSIL) bye: KR. C. Reep, M.A., Trinity Colleges.Cambridge New Bork Mes CV iia NesACN Do CO: AND LONDON 1895 All rights reserved «“ Why, you might take to some light study: conchology, now; I always think that must be a light study.” GEORGE Exiot, Middlemarch. CopyRIGHT, 1895, By MACMILLAN AND CO. | 2029 Norwood 3Bress : J. S. Cushing & Co. — Berwick & Smith. Norwood, Mass., U.S.A. “ny og Coo CL aa a. oh Uta 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. Soe. 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, Reisen im Archipel der Philippinen, ii. 3). 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 V 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 GAA BaAGE RR. INTRODUCTION — POSITION OF MOLLUSCA IN THE ANIMAL KINGDOM — CLASSIFICATION — ORIGIN OF LAND AND FRESH-WATER MOLLUSCA CHAPTER II Lanp AND FRESH-WATER MOLLUSCA, THEIR HABITS AND GENERAL Economy : : : : : : : F CHAPTER UI ENEMIES OF THE MoLuusca — MEANS OF DEFENCE — MIMICRY AND PRO- TECTIVE COLORATION — Parasitic Mo.ntiusca — CoMMENSALISM — VARIATION. eo - - ; ‘ : : : , CH ASR Eire LV Uses oF SHELLS FOR MONEY, ORNAMENT, AND Foop — CULTIVATION OF THE OysTER, MUSSEL, AND SNAIL — SNAILS AS MEDICINE — PRICES GIVEN FOR SHELLS : ; ; : : : ; : : é CECA ER. Vv REPRODUCTION — DEPOSITION OF EGGS — DEVELOPMENT OF THE FERTIL- ISED Ovum — DIFFERENCES OF SEX — DIOECIOUS AND HERMAPHRO- DITE Moititusca — DEVELOPMENT OF FRESH-WATER BIVALVES Vii ho co On (op) 96 Vill MOLLUSCA CHAPTER VI l-ESPIRATION AND CIRCULATION — THE MANTLE z § ‘ 2 .» 450 CHAPTER VU OrGANS OF SENSE: ToucH, SicHT, SMELL, HEARING — TuE Foot — THE NERVOUS SYSTEM . - - ; : - : : ; é ee UE CHAPTER Vii Tue DIGESTIVE ORGANS, JAW, AND RapULA: ExcRETORY ORGANS . 209 CHAPTER IX THE SHELL, ITs Form, CoMposiITION, AND GROWTH — DESIGNATION OF Irs Various ParTS : ; : : é : : : : . 244 CHAPTER X GEOGRAPHICAL DISTRIBUTION OF LAND AND FRESH-WATER MOLLUscA — THE PALAEARCTIC, ORIENTAL, AND AUSTRALASIAN REGIONS . ee CHAP TER xt GEOGRAPHICAL DistrRIBUTION oF Lanp Mo.tvusca (continued) — THE ETHIOPIAN, NEARCTIC, AND NEOTROPICAL REGIONS 328 CHAPTER jat DISTRIBUTION OF MARINE Mo.utiusca — Deep-sEA MOoLuusca AND THEIR CHARACTERISTICS . : : P : : : : : 2 . 9360 CHAPTER XII Crass CEPHALOPODA . : : 5 5 : i x . - » os CONTENTS 1x CHAPTER XIV CxLass GASTEROPODA — AMPHINEURA AND PROSOBRANCHIATA . ; . 400 ; CHAR E iit JV. Crass GASTEROPODA (continued:): OPISTHOBRANCHIATA AND PULMONATA 427 CHAPTER XVI CLASSES SCAPHOPODA AND PELECYPODA . 3 : ; 2 ‘ . 444 BRACHIOPODA (RECENT) CHAPT RRAXV iL INTRODUCTION — SHELL — Bopy — DiGEsTIvVE System — Bopy Cavity — CIRCULATORY SYSTEM — EXCRETORY ORGANS — MuscLes — NERVOUS SysteEM — REPRODUCTIVE SysTEM — EmpryoLtocy — Hasits — Dis- TRIBUTION — CLASSIFICATION ; : : ; : : ‘ . 4638 BRACHIOPODA (FOSSIL) CER AP ER, ox Velih INTRODUCTION — Division I. EcarpINES — EXTERNAL CHARACTERS — IN- TERNAL CHARACTERS — Division II. TEsTICARDINES — 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 Section Eee (p. 382). Beer anche. Phragmophora (p. 386). ata Sepiophora (p. 588). EOSIN { Myopsidae (p. 889). Chondrophora 1 Oi “7d 390 CS igopsidae (p. ): P Retrosiphonata (p. 893). NAUTILOIDEA : ~ Tetra. . Prosiphonata (p. 395). ranchiata ‘ ? Retrosiphonata (p. 397). AMMONOIDEA 4 Prosiphonata (p. 397). ' POLYPLACOPHORA (p.-400). Amphineura 4 4 pLacoPHORA (p. 404). Docoglossa (p. 405). Zygobranchiata (p. DiIoTOCARDIA Le 406). Bhipidoglossa Azygobranchiata (p. 407). Proso- prauchiats. Ptenoglossa (p. 411). . Platypoda (p. 411). Taeniogloss : ¢ MOonorocARDIA Ann. Mag. Nat. Hist. (2) vi. (1880) 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 H. 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 1863, Mr. W. J. Sterland® put specimens of H. 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 Thid. (8) iii. p. 448. 3 Amer. Nat. xi. (1877) p. 100; Proc. Calif. Ac. iii. p. 329. * Gaz. Med. Alger. 1865, 5th Jan. p. 9. 5 Science Gossip, 1867, p. 40. 6 Ann. Mag. Nat. Hist. (2) ix. p. 498. II 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. Veatchii 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 * 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 3 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. 8rd May 1885. Left winter quarters; companion introduced, with which it was seen in company on oth 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 +1 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 8, 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. (8) 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 A. hispida. On the 1st April following, the box was placed in the garden, and on the 3rd 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. xi SELF-BURIAL OF SNAILS AI 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 HA. alliaria (6-8 in.), Hyalinia glabra (5 in.), Helix aspersa (O-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 Pis¢diwm (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 380 eggs on dth September, and 70 more on the 28rd of the same month, although quite isolated during the whole time? By far the most remarkable case of the kind is related by Gaskoin? 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 30 young HA. 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 Arzon 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. Eges 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, 77; 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 30th November, 101; a total of 1 See Tennent’s Ceylon, i. p. 221, ed. 5. 2W. A. Gain, Naturalist, 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. Il HATCHING OF EGGS 43 477. 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 B on 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 can 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 1 T succeeded in hatching out eggs of Helix aspersa, during the very warm summer of 1893, in 17 days. 44 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 5 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 (1th January, 2; 25th January, 2; 11th February, 2), but more abundantly afterwards (8rd April, 60; 15th and 16th, 70; 29th, 53, 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 Avion 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 loth 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. “7 STRENGTH OF SNAILS AS in the same place), but it thinks better of it, and the indentation proceeds no further.1 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 + 0z. He found it could drag verti- cally a weight of 24 oz., or nine times its own weight. Another snail, weighing 4 0z., 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 5? 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. xxxviil. p. 701. 3 Animal Life, Intern. Scientif. Ser. ed. 1, p. 3895. +4 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 Mollusea, 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 mollusean life, Mollusea 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 molluscan 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 turned up; and during June, P/. 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 3 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.4 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. 3 Rey. 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. rh 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 coffee 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.” 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 H. 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 belef, 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 whil- 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 1 P. Z. 8. 1888, p. 358. 2W. A. Gain, Naturalist, 1889, p. 58. 3 Das Wetter, Dec. 1892. Another case is recorded in Amer. Nat. ili. 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. 28-24). 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 Neritina 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: Sphaertum corneum, S. lacustre; Valvata piscinalis, Bithynia 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. 3480. 2 Science Gossip, 1888, p. 281. rt UNDERGROUND AND ROCK-BORING SNAILS 49 habitually from 1 to 38 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 Pfr.), pecuhar to Corsica, which is of dis- tinetly 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.t. I am assured by Mr. EK. L. Layard that precisely similar underground habits are characteristic of Coeliazis 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 } 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 + 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. Il E 50 PRODUCTION OF MUSICAL SOUNDS CHAP. Helix aspersa is said to excavate holes 10 to 12 cm. deep at Constantine, and AH. Mazzullit 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 H. elevata climb trees two days before rain, if it is to be abundant and continuous. MSueccinea 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. (3) xx. p. 576; Bretonniére, Comptes Rendus, cvii. p. 566. 2 Brit. Mus. Collection. 3 Thomas, quoted by Récluz in Journ. de Conch. vii. 1858, p. 178. + Nat. Hist. of Ceylon, p. 382. See also T. L. Taylor, Rep. Brit. Ass. for 1848, p. 82. wt “3 na HABITS OF CARNIVOROUS SNAILS AND SLUGS 5! 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, @ 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 Aynatha, or carnivorous Land Mollusea. 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 Testacella 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. 8 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. Larth- worms are, at these periods, nearer the surface, and the Testacella has been seen creeping down into their burrows. The author has taken 7. Mauget 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 38 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 confuse 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 Limax or Helix, and very large, measuring about ¢ 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 imax 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. Fic. 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. , in. in length, and 4 in. in breadth at its base (see Fig. 54). 7 It appears most probable that "A “Tiyaiinta exvavatu Bean; By Heli the dart is employed as an ad- = fortensis Miill.; C, Helix aspersa junct to the sexual act. Besides fy wie the fact of the position of the dart sac anatomically, we find that the darts are extruded and become embedded in the flesh just before or during the act of copulation. It may be regarded, then, as an organ whose punctures induce excitement prepara- tory to sexual union. It only occurs in well-grown specimens. When once it begins to form, it grows very rapidly, perhaps not more’ than a week being required for its entire formation. The dart is almost confined to Helicidae, a certain number of exceptions being known which border on Helix. Hyalinia nitida and excavata are the only British species, not Helices, which are known to possess it. It has not been noticed to occur in the slugs, except in the N. American genus Tebenno- phorus. About one-third of the British Helices are destitute of the dart... H. rufescens possesses a double bilobed sac, but only two darts, which le in the lower lobes. It does not use the darts, and could not do so, from the relative sizes of dart and sac; it has often been watched when uniting, but the use of the darts has never been observed. From this it has been inferred that the darts are degenerate weapons of defence, and that they were in fact at one time much stronger organs and more often used.2. This theory, however, does not seem consistent with 1C. Ashford, Journ. of Conch. iii. p. 239, iv. pp. 69, 108. 2 W. E. Collinge, Zoologist, 1890, p. 276. 144 HERMAPHRODITE ,MOLLUSCA, GENERATIVE ORGANS _ cuHap. the whole circumstances of the occurrence, position, and pres- ent use of the darts. Hermaphrodite Mollusca. — (6) Digonopora.— As an exam- ple of the Digonopora or hermaphrodite Mollusca with separate generative apertures for the male and female organs, we may take the common Limnaea stagnalis (Fig. 55). It will be seen from the figure that the relative positions of the hermaphrodite gland and duct, and of the albumen gland, are the same as in Helix. When the oviduct parts company from the vas deferens, it becomes furnished with several accessory glands, one of which (GLE.) probably serves as a reservoir for the ova, and answers more or less to a uterus. The tube leading to the spermatheca Fia. 55.— Genitalia of Limnaea stagnalis L. (from a dissection by F. B. Stead), xi. A.G, albumen gland. Ac.G, accessory gland. F.0, female orifice. G1.E, glandular enlargement. H.D, hermaphrodite duct. H.G, hermaphrodite gland. Li, liver. M.O, male orifice. P, penis sac. Pr, prostate. R.M, retractor muscle of penis. Sp, spermatheca. V.D, vas deferens. is short, and there is no divergent coecum. The female orifice lies near to the external opening of the branchial cavity. The vas deferens, which is very long, is furnished with a large pros- tate gland. The penis sac is greatly dilated, and there is no flagellum. The male orifice is behind the right tentacle, slightly in advance of the female orifice (compare Fig. 102). Most of the Opisthobranchiata, but not all, have separate sexual orifices. Numerous variations from the type just de- V GENITALIA; OF PELECYPODA 145 seribed will be found to occur, particularly in the direction of the development of accessory glands, which are sometimes very large, and whose precise purpose has in many cases not been satisfactorily determined. Pelecypoda. — In the dioecious Pelecy poda, v which form the great majority, the reproductive system is simple, and closely parallel in both sexes. It consists of a pair of gonads, which are either ovaries or tests, and a pair of oviducts or sperm-ducts which lead to a genital aperture. The gonads are usually placed symmetrically at the sides or base of the visceral mass. The oviduct is short, and the genital aperture is usually within the branchial chamber, thus securing the fertilisation of the ova by the spermatozoa, which are carried into the branchial chamber with the water which passes through the afferent siphon. Hermaphrodite Pelecypoda are rare, the sexes being usually separate. The following are assured instances: Pecten glaber, P. jacobaeus, P. maximus, Ostrea edulis, Cardium norvegicum, Pisidium pusillum, Cyclas cornea, Pandora rostrata, Aspergilluim dichotomum, and perhaps Clavagella. The greater number of these have only a single genital gland (gonad) on each side, with a single efferent duct from each, but part of the gland is male and part female, e.g. in the Pectens above mentioned. Pandoraand Aspergillum have two distinct glands, respectively male and female, on each side, each of the two glands possessing its separate duct, and the two ducts from each side eventually opening near one another. It appears probable that the Septr- branchiata (Cuspidaria, Poromya, Lyonsiella, etc.) must also be added to the number of hermaphrodite Pelecypoda which have separate male and female glands. It is worthy of remark that all the hermaphrodite Pelecypoda belong to forms decidedly specialised, while forms distinctly primitive, such as Nueula, Solenomya, Arca, and Trigonia are all dioecious. In Gasteropoda similarly, the least specialised forms (the Amphineura, with the exception of the Meomenzidae, and the Rhipidoglossa) are dioecious. It is possible therefore that in the ancestors of the Mollusca the separation of the sexes had already become the normal type of things, and that herma- phroditism in the group is, to a certain extent, a sign or accom- paniment of specialisation.! 1 Pelseneer, Comptes Rendus, cx. p. 1081. VOL. III 1 146 DEVELOPMENT OF LARVAL PELECYPODA CHAP. Development of Fresh-water Bivalves. — The vast majority of fresh-water bivalves either pass the larval stage entirely within the mother, and do not quit her except in a perfectly developed form (Cyclas, Pisidium), or assume a mode of de- velopment in which free larvae indeed occur, but are specially modified for adaptation to special circumstances (Unio). Cyclas and Pisidium, and no doubt all the kindred genera, preserve their ova in a sort of brood-pouch within the gills, in which the ova pass the earlier stages of their development. But, even so, the larva of these genera retains some traces of its original free- swimming habits, for a rudimentary velum, which is quite useless for its present form of development, has been detected in Cyclas. The larva of Dreissensia (see Fig. 47, A), so far as is at present known, stands alone among fresh-water bivalves in being free-swimming, and to this property has been attributed, no doubt with perfect justice, the fact of the extraodinarily rapid spread of Dreissensia over the continent of Europe (chap. xvi.). In expelling the ova, the parent slightly opens the shells and then quickly closes them, shooting out a small point of white slime, which is in fact a little ballof eggs. The general course of development is precisely parallel to that of marine Pelecypoda, greatly resembling, so far as form is concerned, certain stages in the growth of the larvae of Modiolaria and Cardium, as figured by Lovén.1 In June and July the larvae appear in large numbers on the surface of the water, when in spite of their exceedingly small size, they can be captured with a fine hand-net. They pass about eight days on the surface, feeding apparently on minute floating algae. During this time, the principal change they undergo is in the formation of the foot, which first appears as a small prominence midway between the mouth and anus, and gradually increases in length and flexibility. When the larva sinks to the bottom, the velum soon disappears entirely, the foot becomes exceedingly long and narrow, while the shell is circular, strongly resembling a very young Cyclas. Larvae of Unionidae. — The early stages of the develop- ment of Unio and Anodonta (so far as the species of North America, Europe, and Asia are concerned) is of extreme interest, from the remarkable fact that the young live for some time 1 Kon. Vet. Akad. Handl. 1848, pp. 329-455. Vv GLOCHIDIUM OF ANODONTA 147 parasitically attached to certain species of fresh-water fishes. In order to secure this attachment, the larva, which is generally known as Glochidiwm, develops a long filament which perhaps renders it aware of the neighbourhood of a fish, and also a larval shell furnished with strong hooks by which it fastens itself to the body of its unconscious host (Fig. 56). According to some interesting observations made by Mr. O. H. Latter,! the ova pass into the external gill of the mother, in which is secreted a nutritive mucus on which they are sustained until they arrive at maturity and a suitable opportunity occurs for their ‘being born.’ If this opportunity is deferred, and the Glochidia mature, their so-called ‘byssus’ becomes developed, and by being A B Fic. 56.— A, Glochidium immediately after it is hatched: ad, adductor muscle; by, ‘byssus’ cord; s, sense organs; sh, shell. B, Glochidium after it has been on the fish for some weeks: a.ad, p.ad, anterior and posterior adductors; a/, alimentary canal; au.v, auditory vesicle; 67, branchiae; f, foot; mt, mantle. (Balfour.) entangled in the gill filaments of the parent, prevents their escaping. It is interesting to notice that, when the nutritive mucus of the parent is used up, it becomes, as 1t were, the turn of the children to provide for themselves a secondary mode of attachment. The mother Anodonta does not always retain the Glochidium until fish are in her neighbourhood. Gentle stirring of the water caused them to emit Glochidium in large masses, if the movement was not so violent as to cause alarm. The long slimy masses of Glochidiwm were observed to be drawn back again within the shell of the mother, even after they had been ejected to a distance of 2 or 3 inches. It is a mistake to assert that the young Glochidiwm can swim. When they finally quit the mother, they sink to the 1 P. Z. §. 1891, p. 52 f. 148 DEVELOPMENT OF GLOCHIDIUM CHAP bottom, and there remain resting on their dorsal side, with the valves gaping upwards and the so-called byssus streaming up into the water above them. ‘There they remain, until a conven- ient ‘host’ comes within reach, and if no ‘host’ comes within a certain time, they perish. They are eviden‘ly peculiarly sensitive to the presence of fish, but whether they perceive them by smell or some other sense is unknown. ‘“ The tail of a recently killed stickleback thrust into a watch-glass containing Glochidium throws them all inte the wildest agitation for a few seconds ; the valves are violently closed and again opened with astonish- ing rapidity for 15-25 seconds, and then the animals appear exhausted and lie placid with widely gaping shells — unless they chance to have closed upon any object in the water (e.g. another Glochidium), in which case the valves remain firmly closed.” In about four weeks after the Glochidium has quitted its host, and the permanent shell has made its appearance w7thin the two valves of the Glochidium, the projecting teeth of the latter press upon the ventral edge of the permanent shell, at a point about half way in its lengthward measurement, retarding the growth of the shell at that particular point, and indenting its otherwise uninterrupted curve with an irregular notch or dent. As growth proceeds, this dent becomes less and less perceptible on the ventral margin of the shell itself, but its effects may be detected, in well-preserved specimens, by the wavy turn in the lines of growth, especially near the umbones of the young shell. Mr. Latter found that all species of fish with which he ex- perimented had a strong dislike to Glochidiwm as an article of food. Sometimes a fish would taste it “just to try,” but in- variably spit it out again ina very decided manner. The cause of unpleasantness seemed not to be the irritation produced in the mouth of the fish by the attempt of the Glochidiwm to attach itself, but was more probably due to what the fish considered a nasty taste or odour in the object of his attentions. The following works will be found useful for further study of this portion of the subject : — F. M. Balfour, Comparative Embryology, vol. i. pp. 186-241. F, Blochmann, Ueber die Entwickelung von Neritina fluviatilis Mull.: Zeit. wiss. Zool. xxxvi. (1881), pp. 125-174. L. Boutan, Recherches sur l’anatomie et le développement de la Fissurelle; Arch. Zool. exp. gén. (2) iil. suppl. (1885), 173 pp. Vv LIST OF AUTHORITIES 149 W. K. Brooks, The development of the Squid (Loligo Pealii Les.): Anniv. Mem. Bost. Soc. Nat. Hist. 1880. A 7 The development of the oyster: Studies Biol. Lab. Johns Hopk. Univ. i. (1880), 80 pp. R. von Erlanger, Zur Entwickelung von Paludina vivipara: Morph. Jahrb. xvii. (1891), pp. 337-379, 636-680. a Zur Entwickelung von Bythinia tentaculata: Mitth. Zool. Stat. Neap. x. (1892), pp. 376-406. H. Fol, Sur le développement des Ptéropodes: Arch. Zool. exp. gén. iv. (1875), pp. 1-214. , Etudes sur le développement des Mollusques. Hétéropodes: ibid. v. (1876), pp. 105-158. , Etudes sur le développement des Gastéropodes pulmonés: ibid. vill. (1880), pp. 103-232. . Grenacher, Zur Entwickelungsgeschichte der Cephalopoden: Zeit. wiss. Zool. xxiv. (1874), pp. 419-498. . Hatschek, Ueber Entwickelungsgeschichte von Teredo: Arb. Zool. Inst. Univ. Wien, iii. (1881), pp. 1-44. . Horst, On the development of the European oyster: Quart. Journ. Micr. Se. xxii. (1882), pp. 339-346. . Korschelt and K. Heider, Lehrbuch der vergleichenden Entwickelungs- geschichte der wirbellosen Thiere, Heft iii. (1893), pp. 909-1177 (the work is in process of translation into English). A. Kowalewsky, Embryogénie du Chiton polii avec quelques remarques sur le développement des autres Chitons: Ann. Mus. Hist. Nat. Mars. Zool. i. (1883), v. E. Ray Lankester, Contributions to the developmental history of the Mollusca: Phil. Trans. Roy. Soc. vol. 165 (1875), pp- 1-31. is ms Observations on the development of the pond-snail (Lymnaeus stagnalis), and on the early stages of other Mollusca: Quart. Journ. Mier. Sc. xiv. (1874), pp. 365-391. Observations on the development of the Cephalopoda: ibid. xv. (1875), pp. 37-47. W. Patten, The embryology of Patella: Arb. Zool. Inst. Univ. Wien, vi. (1886), pp. 149-174. M. Salensky, Etudes sur le développement du Vermet: Arch. Biol. vi. (1885), pp. 655-759. L. Vialleton, Recherches sur les premieres phases du développement de la Seiche (Sepia officinalis): Ann. Se. Nat. Zool. (7) vi. (1888), pp. 165- 280. S. Watase, Observations on the development of Cephalopods: Stud. Biol. Lab. Johns Hopk. Univ. iv. (1888), pp. 163-183. ae Studies on Cephalopods: Journ. Morph. iv. (1891), pp. 247- 294. E. Ziegler, Die Entwickelung von Cyclas cornea Lam.: Zeit. wiss. Zool. xli. (1885), pp. 525-569. ty WD WwW fF CHAPTER VI RESPIRATION AND CIRCULATION—THE MANTLE THE principle of respiration is the same in the Mollusca as in all other animals. The blood is purified by being brought, in successive instalments, into contact with pure air or pure water, the effect of which is to expel the carbonic acid produced by animal combustion, and to take up fresh supplies of oxygen. Whether the medium in which a molluse lives be water or air, the effect of the respiratory action is practically the same. Broadly speaking, Mollusca whose usual habitat is the water ‘breathe’ water, while those whose usual habitat is the land ‘breathe’ air. But this rule has its exceptions on both sides. The great majority of the fresh-water Mollusca which are not provided with an operculum (e.g. Limnaea, Physa, Planorbis), breathe air, in spite of living in the water. They make periodic visits to the surface, and take down a bubble of air, return- ing again for another when it is exhausted. On the other hand many marine Mollusca which live between tide-marks (e.g. Patella, Littorina, Purpura, many species of Cerithium, Planazis, and Nerita) are left out of the water, through the bi-diurnal recess of the tide, for many hours together. Such species invariably retain several drops of water in their bran- chiae, and, aided by the moisture of the air, contrive to support life until the water returns to them. Some species of Littorina (e.g. our own L. rudis and many tropical species) live so near high-water mark that at neap-tides it must frequently happen that they are untouched by the sea for several weeks together, while they are frequently exposed to a burning sun, which beats upon the rocks to which they cling. In this case it ap- pears that the respiratory organs will perform their functions 150 CHAP. VI MODES OF RESPIRATION ISI if they can manage to retain an extremely small amount of moisture.! _ The important part which the respiratory organs play in the economy of the Mollusca may be judged from the fact that the primary subdivision of the Cephalopoda into Dibranchiata and Tetrabranchiata is based upon the number of branchiae they possess. Further, the three great divisions of the Gasteropoda have been named from the position or character of the breathing apparatus, viz. Prosobranchiata, Opisthobranchiata and Pul- monata, while the name Pelecypoda has hardly yet dispossessed Lamellibranchiata, the more familiar name of the bivalves. Respiration may be conducted by means of — (a) Branchiae or Gills, (6) a Lung or Lung-cavity, (¢) the outer skin. In the Pelecypoda, Cephalopoda, Scaphopoda, and the great majority of the Gasteropoda, respiration is by means of branchiae, also known as ctenidia,? when they represent the primitive Mol- luscan gill and are not ‘ secondary’ branchiae (pp. 156, 159). In all non-operculate land and fresh-water Mollusca, in the Auriculidae, and in one aberrant operculate (Amphibola), res- piration is conducted by means of a lung-cavity, or rarely by a true lung, whence the name Pulmonata. The land operculates (Cyclophoridae, Cyclostomatidae, Aciculidae, and Helicinidae) also breathe air, but are not classified as Pulmonata, since other points in their organisation relate them more closely to the marine Prosobranchiata. Both methods of respiration are united in Ampullaria, which breathes indifferently air through a long siphon which it can elevate above the surface of the water, and water througha branchia (see p. 158). Siphonaria (Fig. 57) is also furnished with a lung-cavity as well as a branchia. Both these genera may be regarded as in process of change from an aqueous to a terrestrial life, and in Siphonaria the branchia is to a great extent atrophied, since the animal is out of the water, on the average, twenty-two hours out of the twenty-four. In the allied genus Gadinia, where there is no trace of a branchia, but 1 The result of some experiments by Professor Herdman upon Littorina rudis, tends to show that it can live much better in air than in water, and goes far to support the view that the species may be undergoing, as we know many species must have undergone (see p. 20), a transition from a marine to a terres- trial life. It was found that marked specimens upon the rocks did not move their position for thirty-one successive days (Proc. Liverp. Biol. Soc. iv. 1890, p. 50). - Diminutive of xreis, a comb. [152 RESPIRATION BY THE SKIN CHAP. only a lung-cavity, and in Cerithidea obtusa, which has a pul- Fia. 57.— A, Siphonaria gigas Sowb., Panama, the animal contracted in spirit: g7, siphonal groove on right side. B, Gadinia peru- viana, Sowb., Chili, shell only: gr, mark of siphonal groove to right of head. monary organisation exactly analogous to that of Cyclophorus, this process may be regarded as practically completed. Respiration by means of the skin, without the development Sara. Qe Fiac.58.— Aeolis despecta Johnst., British coasts. (After Alder and Hancock.) of any special organ, is the simplest method of breathing which occurs in the Mollusca. In certain cases, e.g. Hlysia, Ln- mapontia, and Cenia among the Nudibranchs, and the parasitic Entoconcha and Entocolaz, none of which possess breathing organs of any kind, the whole outer surface of the body appears to perform respiratory functions. In others, the dorsal surface is cov- ered with papillae of varied size and number, which communicate with the heart by an elaborate system of veins. This is the case with the greater number of the Aeolididae (Fig. 58, compare Fig. o, C), but it is curious that when Q\ the animal is entirely deprived of these papillae, respiration appears to be carried on without inter- ruption through the skin. In the development of a distinct breathing organ, it would seem as if progress had been made along two definite linés, each 1 Stoliczka, quoted in Journ. de Conch. xviii. p. 452. VI DEVELOPMENT OF A BREATHING ORGAN 153 resulting in the exposure of a larger length of veins, 7.e. of a larger amount of blood, to the simultaneous operation of fresh air or fresh water. Either (a) the skin itself may have devel- oped, at more or less regular intervals, elevations, or folds, which gradually took the form of papillae, or else (6) an inward fold- ing, or ‘invagination,’ of the skin, or such a modification of the mantle-fold as is described below (p. 172) may have taken place, resulting in the formation of a cavity more or less surrounded by walls, within which the breathing organs were ultimately developed. Sometimes a combination of both processes seems to have occurred, and after a papiliform organ has been pro- duced, an extension or prolongation of the skin has taken place, in order to afford a protection to it. Respiration by means of a luneg-cavity is certainly subsequent, in point of time, to respira- tion by means of branchiae. | The branchiae seem to have been originally paired, and arranged symmetrically on opposite sides of the body. It is not easy to decide whether the multiple form of branchia which occurs in Chiton (Fig. 59), or the simple form as in Fssurella * \ y BAS SS i i. ‘ A i i it i! Hh i's A) Wie z ‘a | 4 >? i 4 \, << Fic. 60.— Fissurella virescens Sowb., Panama, showing position of the Fie. 59.— Chiton squamosus L., Bermuda: branchiae: Br, branchiae; E, E, eyes; A, anus; Br, branchiae; M, mouth. F, foot; M, mantle; T, T, tentacles. (Fig. 60), is the more primitive. Some authorities hold that the multiple branchia has gradually coalesced into the simple, others that the simple form has grown, by serial repetition, into the multiple. There appears to be no trace of any intermediate forms, and, as a matter of fact, the multiple branchia is found 154 BREATHING ORGANS IN AMPHINEURA CHAP. only in the Amphineura, while one or rarely two (never more) pairs of branchiae, occur, with various important modifications, in the vast majority of the Mollusca. Amphineura. — In Chiton the branchiae are external, forming a long row of short plumes, placed symmetrically along each side of the foot. The number of plumes, at the base of each of which lies an osphradial patch, varies from about 70 to as few as 6 or 7. When the plumes are few, they are confined to the pos- terior end, and thus approximate to the form and position of the branchiae in the other Amphineura. In Chaetoderma, the branchiae consist of two small feather-shaped bodies, placed symmetrically on either side of the anus, which opens into a sort of cloaca within which the branchiae are situated. In Meomenia the branchiae are still further degraded, consisting of a single br Fic. 61.— Terminal portions of the Amphineura, illustrating the gradual degradation of the branchiae, and their grouping round the anus in that class. A, Chiton (Hemiarthrum) setulosus Carp., Torres Str.; B, Chiton (Leptochiton) benthus Hadd., Torres Str.; C, Chaetoderma; D, Neomenia; a, anus; br, br, branchiae ; k,k, kidneys ; p, pericardium. (A and B after Haddon, C and D after Hubrecht.) bunch of filaments lying within the cloaca, while in Proneomenia there is no more than a few irregular folds on the cloaca-wall (Fig. 61). In the Prosobranchiata, symmetrically paired branchiae occur only in the Fissurellidae, Haliotidae, and Pleurotoma- riidae, in the former of which two perfectly equal branchiae are situated on either side of the back of the neck. These three families taken together form the group known as Zygo- branchiata In all other families the asymmetry of the body has probably caused one of the branchiae, the right (originally left), to become aborted, and consequently there is only one branchia, the left, in the vast majority of marine Prosobran- | Gyov, a yoke, from the symmetrical position of the branchiae. VI BREATHING ORGANS IN PROSOBRANCHIATA 155 chiata, which have been accordingly grouped as Azygobranchiata. Even in Haliotis the right branchia is rather smaller than the left, while the great size of the attachment muscle causes the whole branchial cavity to become pushed over towards the left side. In those forms which in other respects most nearly approach the Zygobranchiata, namely, the Trochidae, Neritidae, and Turbinidae, the branchia has two rows of filaments, one on each side of the long axis, while in all other Prosobranchiata there is but one row (see Fig. 79, p. 169). In the great majority of marine Prosobranchiata the branchia is securely concealed within a chamber or pouch (the respira- tory cavity), which is placed on the left dorsal side of the animal, generally near the back of the neck. For breathing purposes, water has to be conveyed into this chamber, and again expelled after it has passed over the branchia. In the majority of the vegetable-feeding molluscs (e.g. Littorina, Cerithium, Trochus) water is carried into the chamber by a simple prolongation of one of the lobes or lappets of the mantle, and makes its exit by the same way, the incoming and outgoing currents being separated by a valve-like fringe depending from the lobe. In the carnivorous molluses, on the other hand, a regular tube, the branchial siphon, which is more or less closed, has been developed from a fold of the mantle surface, for the special pur- Pes of conducting water to the Fic. 62. — Bullia laevissima Gmel., branchia. After performing its showing branchial siphon §; purpose there, the spent water does nek i en De not return through the siphon, but cles. (After Quoy and Gaimard.) is conducted towards the anus by vibratile cilia situated on the branchiae themselves. In a.large number of cases, this siphon is protected throughout its entire length by a special prolongation of the shell called the canai. Sometimes, as in Buceinum and Purpura, this canal is little more than a mere notch in the ‘mouth’ of the shell, but in 156 BREATHING ORGANS IN PROSOBRANCHIATA CHAP. many of the Muricidae (e.g. MW. haustellum, tenuispina, tribulus) the canal becomes several inches long, and is set with formi- dable spines (see Fig. 164, p. 256). In Doliwm and Cassis the canal is very short, but the siphon is very long, and is reflected back over the shell. The presence or absence of this siphonal notch or canal forms a fairly accurate indication of the carnivorous or vege- tarian tendencies of most marine Prosobranchiata, which have been, on this basis, subdivided into Stphonostomata and Holosto- mata. But this classification is of no particular value, and is seriously weakened by the fact that Matica, which is markedly ‘holostomatous,’ is very carnivorous, while Cerithiwm, which has a distinct siphonal notch, is of vegetarian tendencies. In the Zygobranchiata the water, after having aerated the blood in the branchiae, usually escapes by a special hole or holes in the shell, situated either at the apex (Fissurella) or along the side of the last whorl (Haliotis). In Pleurotomaria the sht answers a similar purpose, serving as a sluice for the ejection of the spent water, and thus preventing the inward current from becoming polluted before it reaches the branchiae (see Fig. 79, p.-200). In Patella the breathing arrangements are very remarkable. In spite of their apparent external similarity, this genus pos- sesses no such symmetrically paired plume-shaped branchiae as Fissurella, but we notice a circlet of gill-lamellae, which extends completely round the edge of the mantle. It has been shown by various authorities that these lamellae are in no sense mot- phologically related to the paired branchiae in other Mollusca, but only correspond to them functionally. The typical paired branchiae, as has been shown by Spengel, exist in Patella in a most rudimentary form, being reduced to a pair of minute yellow bodies on the right and left sides of the back of the ‘neck.’ longations of the integument, and tentacular Pe etek os, PHOCeBReS in the neighbourhood of, or surround- seizing its prey, Ng the branchiae (see Figs. 58 and 84), or ae ety es even projecting from the whole upper surface (Strebel.) of the body (Fig. 5, C). In the Pelecypoda, the chief organs of touch are the foot, which is always remarkably sensitive, espe- cially towards its point, the labial palps on each side of the mouth, and the siphons. In certain cases the mantle border is prolonged into a series of threads or filaments. These are par- ticularly noticeable in Pecten, Lepton, and Lima (Fig. 85), the mantle lobes of the common ZL. hians of our own coasts being very numerous, and of a bright orange colour. In many genera —e.g. Unio, Mactra —this sensibility to touch appears to be shared by the whole mantle border, although it is not furnished with any special fringing. The ‘arms’ of the Cephalopoda Vil TASTE IN SNAILS 179 appear to be keenly sensitive to touch, and this is particularly the case with the front or tentacular pair of arms, which seem Fic. 84. —Idalia Leachii A. and H., British seas; bv, branchiae. (After Alder and Hancock.) to be employed in an especial degree for exploration and inves- tigation of strange objects. Taste. — The sense of taste is no doubt present, to a greater or less extent, in all the head-bearing Mollusca. In many of these a special nerve or nerves has pharynx, connecting with the cerebral ganglion; this no doubt indicates the seat of the faculty of taste. The Mol- lusca vary greatly in their hkings for different kinds of food. Some seem to prefer decaying and highly odorifer- ous animal matter (Buccinum, Nassa), others apparently confine themselves to fresh meat (Purpura, Natica, Testa- cella), others again, although naturally vegetarian, will not refuse flesh on occasion (Limax, Helix). Mr. W. A. Gain! has made some been discovered in the Fia. 85. — Lima squamosa Lam., Naples, showing tentacular lobes of mantle (f, ¢); a, anus; ad.m, adductor muscle ; b7,)7, branchiae; /, foot; sh, shell. interesting experiments on the taste of British land Mollusca, as evidenced by the acceptance or rejection of various kinds of food. He kept twelve species of Arion and Limaz, and eight spe- cies of Helix in captivity for many months, and tried them with no less than 197 different kinds of food, cannibalism included. 1 Journ. of Conch. vi. p. 349 ff. 180 POSITION OF THE EYES CHAP. Some curious points came out in his table of results. Amalia gagates appears to be surprisingly omnivorous, for out of 197 kinds of food it ate all but 25; Arion ater came next, eating all but 40. Limazx arborum, on the other hand, was dainty to a fault, eating only seven kinds of food, and actually refusing Swedes, which every other species took with some avidity. Cer- tain food was rejected by all alike, e.g. London Pride, Dog Rose, Beech and Chestnut leaves, Spruce Fir, Common Rush, Liver- wort, and Lichens; while all, or nearly all, ate greedily of Pota- toes, Turnips, Swedes, Lettuces, Leeks, Strawberries, Boletus edulis, and common grasses. Few of our common weeds or hedgerow flowers were altogether rejected. Arion and Limax were decidedly less particular in their food than Helix, nearly all of them eating earth-worms and puff-balls, which no Helix would touch. Arion ater and Limax maximus ate the slime off one another, and portions of skin. Cyelostoma elegans and Hyalinia nitida preferred moist dead leaves to anything else. II. Sight Position of Eyes.—In the majority of the head-bearing Mollusea the eyes are two in number, and are placed on, or in the immediate neighbourhood of the head. Sometimes they are carried on projecting tentacles or ‘ommatophores,’ which are either simple (as in Prosobranchiata) or capable of retraction Fia. 86.— A, Limnaea peregra Miill.; e, e, eyes; t, t, tentacles; B, Helix nemoralis Miill.; e, e, eyes; ¢, ¢, tentacles; p.o, pulmonary orifice. like the fingers of a glove (Heliz, etc.). Sometimes, as in a large number of the marine Gasteropoda, the eyes are at the outer base of the cephalic tentacles, or are mounted on the tentacles themselves, but never at the tip (compare Fig. 60, p. 153 and VII ORGANISATION OF THE EYE 18I Fig. 98, p. 199). In other cases they are placed somewhat farther back, at the sides of the neck. The Pulmonata are usually subdivided into two great groups, Stylommatophora and Basommatophora (Fig. 86), according as the eyes are carried on the tip of the large tentacles (Helix, and all non-operculate land shells), or placed at the inner side of their base (Limnaea, Physa, etc.). In land and fresh-water operculates, the eyes are situated at the outer base of the tentacles. In the Helicidae, careful observation will show that the eyes are not placed exactly in the centre of the end of the tentacle, but on its upper side, inclining slightly outwards. The eye is probably pushed on one side, as it were, by the development of the neighbouring olfactory bulb. The sense of smell being far more important to these animals than the sense of sight, the former sense develops at the expense of the latter. Organisation of the Molluscan Eye. — The eye in Mollusca exhibits almost every imaginable form, from the extremely simple to the elab- orately complex. It may be, as in cer- tain bivalves, no more than a pigmented spot on the mantle, or it may consist, as in some of the Cephalopoda, of a cornea, a sclerotic, a choroid, an iris, a lens, an aqueous and vitreous humour, a retina, and an optic nerve, or of some of these parts only. In most land and fresh-water Mol- lusca the eye may be regarded, roughly speaking, as a ball connected by an exceedingly fine thread (the optic nerve) ye. 97, — Eye of Helix poma- with a nerve centre (the cerebral gang- tia L., retracted within the lion). In Paludina this ball is elliptic, ca are er. ae in Planorbis and Neritina it is drawn _ op.n, optic nerve; 7, ret- out at the back into a conical or pear (After Simroth.) shape. In Helix (Fig. 87) there is a structureless membrane, surrounding the whole eye, a lens, and a retina, the latter con- sisting of a nervous layer, a cellular layer, and a layer of rods containing pigment, this innermost layer (that nearest the lens) being of the thickness of half the whole retina. Comparing the eyes of different Gasteropoda together, we 182 STAGES OF DEVELOPMENT IN THE EYE CHAP. find that they represent stages in a general course of develop- ment. Thus in Patella the eye is scarcely more than an invagi- nation or depression in the integument, which is lined with pigmented and retinal cells. The next upward stage occurs in Trochus, where the depression becomes deeper and bladder- shaped, and is filled with a gelatinous or crystalline mass, but still is open at the top, and therefore permits the eye to be Fic. 88. — Eyes of Gasteropoda, showing arrest of development at successive stages: A, Patella; B, Trochus; C, Turbo; D, Murex ; ep, epidermis; /, lens; op.n, optic nerve; 7, retina; v.A, vitreous humour. (After Hilger.) bathed in water. Then, as in Yurbo, the bladder becomes closed by a thin epithelal layer, which finally, as in some Murez, be- comes much thicker, while the ‘ eyeball’ encloses a lens (Fig. 88), which probably corresponds with the ‘ vitreous humour’ of other types. In Nautilus the eye is of a very simple type. It consists of a cup-shaped depression, with a small opening which is not quite closed by the integument. The retina consists of cells VII EYE OF CEPHALOPODA 183 which line the interior of the depression, and which communicate directly with the branches of the optic nerve, there being no iris or lens. This type of eye, it will be observed, corresponds exactly with that which occurs in Patella. It appears also to correspond to a stage in the rs e mo USPNILEALIRA AN \ development of eyes in the Di- Sea B 3S eee branchiata (e.g. Octopus, Sepia, Loligo). WUankester has shown ! that in Loligo the eye first ap- pears as a ridge, enclosing an oval area in the integument. By degrees the walls of this area close in, and eventually join, enclosing the retinal cells within the chamber in which the lens is afterwards developed sige nee rato. ae ee (Fig. 89). It thus appears that enclosing p.0.€, primitive optic cham- in some cases the development Di 0" orice betwoon tho closing of the eye is arrested at a point Gb. Ci, ciliary body; 7, rudimentary which in other cases only forms _*°"** # "tina. (Alter Lankester. ) a temporary stage towards a higher type of organisation. The developed eye in the dibranchiate Cephalopods consists of a transparent cornea, which may or may not be closed over Fic. 90.—Eye in A, Loligo; B, He- liecor Limax.--C, Nautilus: a.o.e, anterior optic chamber; c, cor- nea; int, integu- ment; 27, iris; > Wy T ‘ NS \ WV \\\\ g Y \ 4 aoe B\\\i “Ve \. \ Ps | a —<—— 30 | SS"; 4 ~ PET eg aRee ot ceaett gnu oe Se Ere Wt \\\\ I} || Fic. 106.— Nervous system of Cardium edule L.: a.m, anterior adductor muscle; br, branchiae; b7.n, branchial nerve; c.g, c.g, cerebral ganglia; c.p.c, cerebro-pedal commissure; ¢.v.c', cerebro-visceral commissure; c.v.c, cerebro-visceral commis- sure of mantle; l.p, labial palps: 7, mouth; p.g, pedal ganglion; p.m, posterior adductor muscle; v.g, visceral ganglion. (After Drost, x 3.) can be detected. The pedal ganglion becomes separated into two portions, one of which innervates the arms, the other the funnel. Two peculiar gangla (the stellate ganglia) supply a number of branching nerves to the mantle. E.L. Bouvier, Systéme nerveux, morphologie générale et classification des Gastéropodes prosobranches: Ann. Se. Nat. Zool. (7), ii. 1887, pp. 1-510. J. Brock, Zur Neurologie der Prosobranchier: Zeit. wiss. Zool. xlviii. 1889, pp. 67-85. O. Butschli, Bemerkungen iiber die wahrscheinliche Herleitung der Asym- metrie der Gasteropoda, ete.: Morph. Jahrb. xii. 1886, pp. 202-222. B. Haller, Zur Kenntniss der Muriciden. I. Anatomie des Nervensystems: Denksch. Math. Nat. K]. Ak. Wien, xlv. 1882, pp. 87-106. Untersuchungen tiber marine Rhipidoglossen. II. Textur des Centralnervensystems und seiner Hiillen: Morph. Jahrb. xi. 1885, pp. 319-436. ” 208 AUTHORITIES CHAP. VII H. Grenacher, Abhandlungen zur vergleichenden Anatomie des Auges: Abh. Naturf. Gesell. Halle, xvi. 1884, pp. 207-256 ; xvii. 1886, pp. 1-64. A. P. Henchman, The Origin and Development of the Central Nervous System in Limax maximus: Bull. Mus. C. Z. Harv. xx. 1890, pp. 169-208. V. Hensen, Ueber das Auge einiger Cephalophoren: Zeit. wiss. Zool. xv. 1865, pp. 157-242. C. Hilger, Beitrige zur Kenntniss des Gasteropodenauges: Morph. Jahrb. x. 1885, pp. 352-371. Lacaze-Duthiers, Otocystes ou Capsules auditives des Mollusques (Gastéro- podes): Arch. Zool. Exp. Gén. i. 1872, pp. 97-166. Du systéme nerveux des Mollusques gastéropodes pulmonés aquatiques: ibid. pp. 437-500. P. Pelseneer, Recherches sur le systéme nerveux des Ptéropodes: Arch. Biol. vii. 1887, pp. 93-130. Sur la valeur morphologique des bras et la composition du systéme nerveux central des Cephalopodes: Arch. Biol. vill. 1888, pp. 723-756. H. Simroth, Ueber die Sinneswerkzeuge unserer einheimische Weichthiere : Zeit. wiss. Zool. xxvi. 1876, pp. 227-548. J. W. Spengel, Die Geruchsorgane und das Nervensystem der Mollusken : Zeit. wiss. Zool. xxxy. 1881, pp. 333-383. 39 99 CHAPTER VIII THE DIGESTIVE ORGANS, JAW, AND RADULA: EXCRETORY ORGANS THE digestive tract, or, as it is often termed, the alimentary canal or gut, is a very important feature of the Mollusca. It may be regarded as consisting of the following parts: (1) a mouth or oral aperture; (2) a throat or pharynx ; (8) an oesoph- agus, leading into (4) a stomach, (6) an intestine and rectum, ending in (6) an anus. The primitive positions of mouth and anus were presumably at the anterior and posterior ends of the animal, as in the Amphineura and symmetrical Mollusca generally. But the modifications of original molluscan symmetry, which have already been referred to (p. 164, compare pp. 245, 246), have resulted in the anus becoming, in the great majority of Gastero- poda, twisted forward, and occupying a position on some point in the right side in dextral, and in the left in sinistral species. The process of digestion, as the food passes from one end of the tract to the other, is performed by the aid of the secretions of various glands, which open into the alimentary canal at different points in its course. The principal of these are the salivary glands, situated on the pharynx and oesophagus, and the liver, biliary or hepatic gland, connecting with the stomach. With these may be considered the anal and ink-glands, which, in certain genera, connect with the terminal portion of the rectum. 1. The mouth is generally, as in the common snail and peri- winkle, placed on the lower part of the head, and may be either a mere aperture, circular or semicircular, in the head-mass, or, as is more usual, may be carried on a blunt snout (compare Fig. 6, p. 10, and Fig. 68, p. 159), which is capable of varying degrees of protrusion. From the retractile snout has doubtless been VOL, Ill 209 P 210 THE PROBOSCIS, PHARYNX, AND JAWS CHAP. derived the long proboscis which is so prominent a feature of many genera (compare Figs. 1, B, and 99), and in some (e.g. Mitra, Dolium) attains a length exceeding that of the whole body. Asa rule, Mollusca provided with a proboscis are carniv- orous, while those whose mouth is on the surface of the head are vegetable feeders, but this rule is by no means invariable. The mouth is thickened round the aperture into ‘ lips,’ which are -often extensile, and appear capable of closing upon and grasping the food. In the Pelecypoda the mouth is furnished, on each side, with a pair of special external lobes, the ‘labial palps,’ which appear to be of a highly sensitive nature, and whose object it is to collect, and possibly to taste, the food before it passes into the mouth. 2. The Pharynz, Jaws, ant Radula.— Immediately behind the lips the mouth opens into the muscular throat, pharynx, or buccal mass. The pharynx of the Glossophora, 7.e. of the Gas- teropoda, Scaphopoda, and Cephalopoda, is distinguished from that of the Pelecypoda,! by the possession of two very charac- teristic organs for the rasping or trituration of food before it reaches the oesophagus and stomach. ‘These are (a) the jaw or jaws, and (6) the radula,* odontophore, or lingual ribbon. The jaws bite the food, the radula tears it up small before it passes into the stomach to undergo digestion. The jaws are not set with teeth like our own; roughly speaking, the best idea of the relations of the molluscan jaw and radula may be obtained by imagining our own teeth removed from our jaws and set in parallel rows along a greatly prolonged tongue.® In nearly all land Pulmonata the jaw is single, and is placed behind the upper ip. If a common Helix aspersa be observed crawling up the inside of a glass jar, or feeding on some succu- lent leaf, the position and action of the jaw can be readily dis- cerned. It shows very black when the creature opens its mouth, and under its operation the edge of a lettuce leaf shows a regular series of little curved indentations, in shape not unlike the semi- 1 There is practically no pharynx in the Pelecypoda, the mouth opening directly into the oesophagus. 2 Radere, to scrape; ddovs, tooth; Péperv, to carry. 3 The mechanism of the radula has been dealt with by Geddes, Trans. Zool. Soc. x. p. 485. Riicker has observed (Ber. Oberhess. Gesell. Nat. Heilk. xxii. p. 207) that the radula in Helix pomatia is the product of five rows of cells; the use of the first row is uncertain, the second forms the membrane of the radula, while rows three to five originate the teeth. VI THE JAW IN PULMONATA PAI | circular bites inflicted by a schoolboy upon his bread and butter. The jaw of Helix (Fig. 107, B) is arched in shape, and is strengthened by a number of projecting vertical ribs. That of Limaz (A) is straighter, and is slightly striated, without vertical ribs. In Bulimulus (C) the arch of the Jaw is very conspicuous, and the upper edges are always denticulated: in Orthalicus there is a central triangular plate with a number of overlapping plates on either side; in Succinea (I) there is a large square accessory plate above the jaw proper. The form of the jaw is peculiar not Fig. 107.— Jaws of various Pulmon- ata: A, Limaz (gagates Drap., Lancashire, 15); B, Helix (acutis- sima Lam., Ja- maica, x 15); C, Bulimulus (de- pictus Reeve, Venezuela, x 20); Py CALC TOE 2 10.0 (fulica Fér., Mau- ritius, <7); E, Succinea (elegans Riss., Aral Dis- triGte x oO). FB; Limnaea (stag- nalis L., Cam- bridge, x 30). only to the genus but to the species as well. Thus the jaw of H. aspersa is specifically distinct from that of H. pomatia, and that of H. nemoralis is distinct from both. Wiegmann has observed! that in young Arion, Limar, and Helix, the jaw con- sists of two pieces, which coalesce by fusion in the adult, thus indicating a stage of development in advance of the double jaw which is found in most of the non-pulmonate Mollusca. In all fresh-water Pulmonata there are two small accessory side plates. besides the jaw proper (Fig. 107, F). | Nearly all the non-carnivorous Prosobranchiata, land, fresh- water, and marine alike, are provided with two large lateral jaws. 1 Jahrb. Deut. Malak. Gesell. iii. p. 193. aie aA LN PROSOBRANCHIATA AND OPISTHOBRANCHIATA CH. Many of these are sculptured with the most elaborate patterns, and appear to be furnished with raised teeth, like a file. In the FE i, KP LL dy Fic. 108. —Jawsof A, Triton australis Lam., Sydney; B, Ampullaria fasciata Reeve, Demerara; C, Calliostoma punctulatun Mart., New Zealand; D, Cyclophorus atramentarius Sowb., Sanghir; all x 15. Fic. 109. — Jaws of A, Chromodoris gracilis Iher., x 15; B, Scyllea pelagica L., x 7; 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, Glundina, Streptavis, 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 (Fig. 110). The Radula.1A— 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 Rey. 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 Taentoglossa 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; i, i; intestine; J, Fic. 110.— Jaws of Sepia: A, in situ liver; m, m, mantle edge; mu, within the buccal mass, several of muscles (cut through) fastening the the arms having been cut away ; visceral mass to the upper sides of B, removed from the mouth and the foot ; ov, ovary; 7, radula; u.f, slightly enlarged. 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. J 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.”” vl TEETH OF THE RADULA ZH: 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.t It hes 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 greatly 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 CHAP. 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 a rae ST a a rd through disuse, the animals hay- Reeve, Panama), much worn by ing taken to a food which does not eo 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 proboscis compen- sates for the loss of radula (see pp. T6-77). 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 Neomenia, 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. VIII NUMBER AND ARRANGEMENT OF TEETH 217 Genera which are normally vegetarian, but which will, upon occasion, eat flesh, 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 Glaueus atlanticus about 21,in Mona nobilis about 28. In the common whelk (Buccinwm undatum) there are from 220 to 250, in the common periwinkle about 3500. As many as 8343 have been counted in Limnaea stagnalis, about 15,000 in Helix aspersa (that is, about 400,000 to the square inch), about 50,000 in Limaxc maximus, and as many as 40,000 in Helix Ghies- 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- cerned. 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 invariably 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 /aterals, while the outermost are styled wncini 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 218 VALUE IN CLASSIFICATION CHAP. and family, the radula is characteristic. In closely allied species 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 of genera and species. For instance, in the four known recent genera of the family Strombidae, viz. Strombus, Pteroceras, Rostellaria, and Terebel- lum, the radula is of the same general type throughout, but with 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 — (a) Tozxoglossa (6) Rachiglossa ( Monotocardia | (c) Taenioglossa (d) Ptenoglossa Prosobranchiata | (e) Gymnoglossa { (f) Rhipidoglossa Diotocardia ] (a). Deen (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 hae 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; paxis, ridge, sharp edge; raivia, ribbon; mrnvés, winged ; yuuvos, bare; piris, fan; doxds, beam. Vul 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 Fic. 114.— Portion of radula of Spiro- tropis carinata Phil., Norway. x70. Fie. 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: aoe Ae, where 30 and 42 stand for the average number of rows of teeth in Conus and Spirotropis respectively ; the same is sometimes expressed thus: MeO scosOle LL «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 Melongena vespertilio Lam., Ceylon. x 30. Fig. 116.— A tooth from the radula of Conus imperi- alis L.,S. Pacific, x 50, showing barb and poison duct. Fig. 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 O22) | group are the possession of a central tooth with from one cusp (Boreofusus) to about fourteen (Bullia), and a single 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 Fic. 120 — Portion of the radula of Imbricaria the laterals are bicuspid ; murnorata 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. Fie. 122.—Six teeth Marginella has no laterals; the central tooth from the radula of . : Cymbium diadema 18 Small and comb-shaped, with blunt cusps. pos torres Strait. In Voluta the laterals are generally lost, but fs 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. 222 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. 9 Of the Mitridae, Cylindromitra has lost the laterals. Among the - ; Buccinidae, Buccinopsis possesses H a curiously degraded radula, the central tooth having no cusps, but being reduced to a thin basal A’ plate, while the laterals are also weakened. This degradation from the type is a remarkable feature —— among radulae, and appears to 5 ae be characteristic, sometimes of a fete errs ele ade raed fortis whole family, e.g. the Columbeili- of radula: A, Cantharus pagodus dae (Fig. LZ. B); sometimes of Reeve, Pana oaseent en) 40: 4 genus, sometimes again of a portion; B, Columbella varia Sowb., single species. Thus in Cantha- ema 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 Fic. 124. — Three rows of the radula of Sistrum spectrum Reeve, Tonga. x 80. The laterals to the right are not drawn in. 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 Sistrum 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. (c) 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- \(\ Fic. 125. — Portion of the radula of Cassis su/cosa Born., x 40. 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 Fic. 126.— Four rows of teeth from the radula of Vermetus grandis Gray, Andamans. x 40. cusped. The accompanying figures of Cassis, Vermetus, and Cypraea, and those of Littorina 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 Cyclostoma- Fig. 127.—Two rows of the radula of Cypraea tigris L. x 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. Solariwin 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 Torinia 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 Yaenioglossa is 2.1.1.1.2; in Lamellaria, 1.1.1; in Triforis, 18.1.18, 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 Scalarii- dae. In all probability their approximation is only provisional. The Fie. 128. — Portion of the radula of Janthina yadula, which in Janthina comniunis Lam. x 40. is very large, and in Sea- larva very small, possesses an indefinite number of long hooked VIII RADULA OF THE PTENOGLOSSA, ETC. 225 teeth, of which the outermost are the largest. The central tooth, if present (it does not occur in Janthina), is the smallest in the series, and thus recalls the arrangement in some of the carnivorous Pulmonata (p. 232). In Lanthina 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. Fia. 129. — Portion 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 (Weritopsis) 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, Livona 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, V1Z.: — (1) 5.1.5.0, ze. one central, five laterals, including the ‘last lateral’ tooth. (2) (o.1).4.1.4.(1.0 ), regarding the ‘last lateral’ as first uncinus, but specialising it by a number. (3) o.1.(4.1.4).1.0, regarding the ‘last lateral’ as the only lateral. In the Neritidae and the derived fresh-water genera (Neritina, 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. ~ 40. very large, and in shape rather like the blade bone of a shoulder of mutton; the intervening laterals are very small. In Neri- 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 Halvotis, Scissurella, and. Pleurotomaria the five laterals are of fauly 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 Fie. 131.— Portion of the radula ; : ; : 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 multipl- 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 Pte7ro- trachea mutica Les., Naples. x 60. Pectinodonta, 2.2.1 +0 +41).2.2 in Collisellina (both Acmaei- dae), to 3.2.01 + 0 +1).2.3 in Patinella, and 3.1.(2 + 0 + 2).1.8 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, 2.071.032: 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 Fiac. 133.— A, 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. ereater, 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).(24+1) .2.(1+2).d1+8) or (84+1).(24141).1.0414+2).(14+8). : (6) Aplacophora.— Of this rather obscure order, Chaetoderma has a single strong central tooth, Meomenia has no radula, VII 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 ibe Be a" avi \ \\ | | \ ‘ \ f WW f hf \ \ ‘ , ‘eee a \s eg — = a : Y <> 7 J Fic. 1584. — 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); ZIdalia, Anecula, 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 Ozynoe, 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), Ringicula, 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- ~— se 4 LGU ESN LUTE NP Now SS = ZY Ugn~s SST“ Fic. 135.— Radula of Elysia Fig. 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), Idalia, and Ancula. (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 Aypobranchiaea 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. VII RADULA OF PULMONATA 221 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 Rhytida, 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- Fic. 137. — Portions of the radula of Opisthobranchi- ata, illustrating types ()) 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, Fic. 138. — Portion of the radula of Glandina trun- cata Gmel. x 40. gradually 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 Wanina, Helicarion, Limax, Parmacella, and all the subgenera of Zonites. It is certain that some, and probable that all of these genera will, | ' Fig. 139. — Portion of the radula of Rhytida Kraussit Pir., 3S; > Adrica: 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. Vill RADULA OF PULMONATA 235 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 oi 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 shght approxi- mation to the Zonitidae 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 Bulimul/dae, 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); (2) radula long and narrow, central tooth as in (@), 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 (6) 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; (@) 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 pines fm GEOGRAPHICAL DISTRIBUTION a GR) oO of the Land Mollusca of the s ve EAST INDIAN ARCHIPELAGO = < The red line marks the 100 fathom line 35 N ~ English Miles Ss I A M oe OQ 2 _1g0_150 5 { - 16 s o F poo™ Luban|\s, ? ' ot Min ae OW 3 2000 b 00° Basuang Opfash es 1 = ar to va Calami uve S F r shay sha a) a Di e Dp 0 ae 8 Ps & fathoms ae yi 2 by) {oy SOQ-LOO v ‘ % 400° = IRataha 5 2000 |to 2000 AKG wz : 4 . 500 @ Balainbang % iS te J Pelew F Q Bellow fo A 6 Si an Ww Xa OAS 1ol00 100 {Tawi a ; a) iD wane 2000 oO fathoms % Ss fa odd i S id 0 QSanghur Gralarce) tenric , OOo Sate, por 3 ee lautse J?| ¢ 4 (as , q Ve fathoms ° . eS to ee = 3000 . S582 7 a iB Om wl <6 (forsale, 0140 fathoms oy ° 100 jane Was} B or 7 : r = SY | 2 \Y ; so a eee ee ft AQ. : a es CELEB oo er al a oO = Q a ’ Xalla|I* % ta ee er V 3 es zz. ie; In . 3 Below |100 fathom: x eT SUINEA 2 elow a af 2000 pr et Sy ~ 5 < ‘ , : 4k SA ety) ay asi isp ica a 3000 pe 1G One ar es .100 |to 500 fathoms fathoms : -. = Vv eo eam ber I> A Flores _ > 9 Fimor Laut - AAP TRE oh ES) iy 2 : oe ae ot fathoms ws #20 au v° Pi a 0) 1000 fa te iin te 110" Y ww 400 iL 10 : Below 3000 fathonn Dail I MOR SEA 95 Longitude E.100 of Greenwich 105 no 5 120 126 180 135 London. Stanso sta London: Macmillan & Co. 308 MALACCA — SUMATRA This islands which s panying would t greater these is] very sha of the n ine and Boi with on parative! their lan Fis. 207.— phitv Tenimbe Ké Is., 1 are as Pi the Banc appear t free fron Australiz remarked own, unl serve as { The . what the one-half 1 to the gr with Bur with Siar and Ceyle Nee mee - enim s- 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, Rhiostoma 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- ; : ee stoma grandispinosum Amphidromus is a genus characteristic G.-A., Borneo. Both of the great Sunda Islands, attaining its AS. maximum in Java (12 sp.). The Indian Glessula still has ohne species each in Sumatra, Java, and Borneo. One species of Streptazis! occurs in Malacca, but Hnnea (3 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 CHAP. 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. Clausilia 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 eround, in proportion to the Helicidae, FE MA indents Macrochlamys, for instance, being repre- perversus L., Java. sented by only one species, and Hemzplecta 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 52 51 22 36 40 Helix (all genera) i i 15 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 8 to 1in 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 Moluceas the scale turns and Heliz has the advantage by about 8 to 5, and in N. Guinea by more than 2 to 1. 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.andS.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 snr which Obba and Obbina occur, shows decided relationship with the Philippines, while the occurrence of three CAloritis and one Planispira tend to approximate 8. 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 on all 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 8 Chloritis, and there is one (supposed) Corasia. Two Helices of a marked Australian type (thagada) occur, one in Flores, the other on Dama I., south-west of Timor. The con- figuration 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 T 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, 5 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, Heliz 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 383 to 13, 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 . JA,4T ‘Paunus . | <= A Euplecta . . LAr sObbina..<. = LA,? ET. Vivipara. -age 1A esta #, .-.< | GAYA Phania,..> - 4T Acmella. 2 1A Macrochlamys 1A Albersia . . oT Diplommatina. 4 A, 2T Lamprocystis 4A,27T Camaena . 1T £Registoma . . 3 Macrocycloides AA) 6Papuina... © 1A, 77 “Pupmella yas 1A sitala;. of .. 1A APUpaie. 2 s \. 3 Gallia 2 ae 2A Kaliella 2 -2~%3,.A,1T Vertigo . . 2A Leptopoma. . 4A,5T Trochomorpha 38A,3T Clausilia. . 1T Lagochilus . <> Aye Endodonta . 1A Opeas.. 4A,4T Ditropis sues 3A Patula .. 1A Subulina. . 1A Cyclotus . . 44768 Plectotropis . 1T = ‘Tornatellina 1A Omphalotropis 3A Eulota .. 1A Vaginula . 1A. Georissa. . % 1 Chioritis..... SA Melania . .18A,4T ~—Helicnma. «= 645e0 iRigmispira. < 5-4, 122 (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 Fig. 210. — Cochlostyla (Chry- Fic. 211.— Cochlostyla (Ortho- sdlis) mindoroensis Brod., stylus) Porteit Reeve, Luzon. Mindoro, Philippines. x 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 8. 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. S. 1892, pp. 447-469. 314 THE PHILIPPINES CHAP. Other forms peculiar to the Philippines are Diaphora, a section of Ennea with a curi- ously produced mouth, and several sub-genera of the Naninidae ( Vitriniconus, Vit- rinoidea, Hemitrichia). The great Rhysota here find their metropolis. Another very —— marked group of Helix is Fic. 212. — Helix (Obbina) rota Brod., Obbina, 19 of the 25 known Philippines. : - : 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 TZrachia 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 Manina and Cyclophorus, which here attain almost Indian dimensions; in Kaliella (8 sp.), Sitala (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. Streptaris, Hypselostoma, Ditropis, Acmella, 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 Zennentia 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 3 Xesta 2 Plectopylis 3 Cochlostyla. 247 Tennentia . 1 Macrochlamys 5 _ Plectotropis 1 Amphidromus. 2 Helicarion . 21 Microcystis 3 Aulacospira 3 Hapalus (?) + Vitrinopsis 5 Lamprocystis . 17 Pupisoma 1 Hypselostoma. 1 Vitrinoidea 1 Bensonia 4 Satsuma 2 Pupa 4 Rhysota . 17 Vitriniconus . 16 Dorcasia 2 Clausilia 1 Trochonanina 2 Sitala 2 Chloritis . 7 Subulina 5) Euplecta 28 Kaliella 8 Obbina . 19 Prosopeas 2 x ISLANDS ADJACENT TO THE PHILIPPINES 315 Opeas 4 Melania . . 50 MHargreavesia . 1 Cyathopoma . 5 Geostilbia . 1 Pirena 2 Callia 2 »Cyclotus. =. . 19 Tornalellina 1 Bithynia 1 Pupinella 3 Omphalotropis 3 Succinea 3 Vivipara 7 Helicomorpha 4 Helicina . . 18 Vaginula 2 Ampullaria 5 - .Coptechilus- .° 1 &Georissa 7.......3 Ancylus 1 Acmella 2 Alycaeus 1 Limnaea 3 Diplommatina 41 Leptopoma . 42 Anodonta . . 1 Planorbis 3 Arinia 6 Lagochilus . I; Cyrena .. 33.38 Physa 2 Pupina . 5 Cyclophorus . 381 Corbicula . . 7 Registoma . 7 Ditropis ri 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 Balabae, 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 Obdba, 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. 213) are rather prevalent. In several cases —e.g. T'richia 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- lusea are not abundant, and are rep- resented by Rathovisia (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 HSCS NUT GLEE be the European Napaeus. 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. Heudeia 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 zi 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 Ennea . 12 Aegista. . .10 Limnaea 2 Cyclophorus 18 Parmarion . 2 Armandia . 3 Planorbis 6 Coelopoma . i! Helicarion . 15 Acusta 15 Melania. . . 44 Pterocyclus 3 Euplecta 3 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 Hydrobia 2 Helicina. 3 Hemiplecta 1 Buliminopsis . 8 Mecongia 1 Georissa. + Trochomorpha 2 Buliminidius 3 Oncomelania . 9 MHeudeia. 1 Limax 1 Napaeus 14 Margaracya 1 Cyclas 1 Philomycus 1 Rachis (?) . 4 Rivularia 4 Corbicula 50 Patula 2 Pupa 10 Delavaya Lone: . . OO Gonostoma. 4 Clausilia . 102 Fenouillia . 1 Monocondylaea 1 Metodontia 2 Opeas .. .12 Vivipara 34 Anodonta 5d Vallonia 1 Euspiraxis. . 1 Diplommatina 20 Mycetopus. 12 Plectotropis . 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 Mollusea 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 Streptaxis, 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 Clawsilia, 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. (b) 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, Pupinelia, 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; (6) 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 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 southand south-east, and of the Solomons and 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 (13 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 a single Corasia serves to form a link between the Corasia 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 (3), 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 Sitala (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 Lsidora (3 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. . 3 Calycia 4 Diplommatina 1 Helicarion 2 Ochthephila(?) 1 Partula 3 Pupina;:— os oni expe: : 3 — Ww: 2 : Ome. Bw. Crw. GREATER ANTILLES S g z 3 3) 5 A 5 a ee os 2 pC?) 1 iu ae 1 13 — for) 2 moos OCObO® or: (oof dl — tee ee 14 es se 7 ae 2 i 3 =, 6 me 34 - 1 S 6 eras ~ 1 “2 «414 14-9 36-385 es 1 7 (2) : oo Porto Rico. a] So) — ee > =D bh: . mM O92 Coe to: 3 COia el ec ee hf — rs ee 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 . Eutrochatella Lucidella | Aleadia | Helicina Proserpina. > pO =1b0 ooo Cuba. > jm > Jamaica. to: bo §. Domingo. Ch aS 7 4 7, é ° ci enka mboor:s cos COR: — bo : = 5 : © OOWH Orit. - ee) STMOTUOS) 6 os os 1 80 1 6 6 4 1 14 4 16 924 4 : 351 bobo co! 2 0: et noo Porto Rico. - Wr WR bw: The Virgin Is., with St. Croix, Anguilla, and the St. Bar- tholomew group (all of which are non-voleanic islands), are related to Porto Rico, while Gaudeloupe and all the islands to the south, up to Grenada (all of which are voleanic), 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 8. American forms in the Lesser Antilles, is shown by the following table: — ; Thomas. . Croix. Anguilla, St. Kitt’s. Antigua. Guadeloupe. Dominica. Martinique. St. Lucia. Barbados. St. Vincent. Trinidad. Bulimulus Cylindrella Macroceramus é Cyclostomatidae, etc. . Dentellaria Cyclophorus . Amphibulimus Homalonyx S o° _ = = = = | m PR 1 3 3 re ona | Tortola. woe 23 hoe OR: RO Aooboot: 5: (d) In Guadeloupe we find Cyclophorus, Amphibulimus, Homalonyx, 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. Stragglers 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 S$. Lucia, where also is found a Parthena (San Domingo and Porto Rico). Trinidad is markedly 8. American ; 59 species in all are known, of which 22 are peculiar, 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 (intro- 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 isthmus of Panama in the south. It thus impinges on three important districts—the N. American, West Indian, and 8. 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; 36 of Streptostyla (S.E. Mexico and Guatemala, only 1 species reaching Venezuela and another Peru); 5 of Sala- siella, 2 of Petenia, and 1 of Strebelia; the last three genera being peculiar. Strept- axis, fairly common in S. 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 Fic. 232.—Examples of region are the giant forms belonging to the _ characteristic Mexican < 2 : ele = . Mollusea: A, Coelocen- Cylindrellidae, which are known as Holo- RN. Fl ree eae spira, Eucalodium, and Coelocentrum (Fig. — Streptostyla Delattrei 232). They are almost entirely peculiar “ine to Mexico, only 7 out of a total of 33 reaching south of that district, and only 1 not occurring in it at all. : VOL. Ill 2A 354 CENTRAL AMERICA CHAP. The land operculates are butscanty. Tomocyclus 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 Heudeza), are quite pecuhar. Pachychilus, one of the characteristic fresh-water genera, belongs to the S. 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 2 s & 2 = a He aes eS Wo Sees 2 OEE eo 2 SES co} = Odds O08 = O45 O28 Strebelia 1 ae ...| Berendtia . i| aS Glandina 33 18 3 | Orthalicus 6 3 3 Salasiella 4 sts 1) Pupa 1 1 1 Streptostyla. 18 12 6 | Vertigo 1 dss sae Petenia os 1 1 | Holospira 12 rae es Limax : Bhd ase 1 ... | Coelocentrum 6 1 1 Velifera ‘ sie Nicies 1 ... | Eucalodium . 15 are 5 Omphalina Biel Lt) 1 1| Cylindrella . 6 qd re Hyalinia 2 5 3 | Macroceramus 2 1 te Guppya : Sas 8 3 | Simpulopsis . 2 1 ly. Pseudohyalina 2 2 | Caecilianella 1 BE = Tebennophorus . 1 es =. | Opeds.. 1 2 = Cryptestracon ;. .. 1 ... | Spiraxis 8 2 1 Xanthonyx . 4 sits Leptinaria sins 2 es Patula . : 3 Sui 4 | Subulina 2 3 + Acanthinula. 1 2 2 | Succinea i 3 1 Vallonia as 1 Vaginula 1 due aes Trichodiscus 2 2 3 | Aperostoma . sae 4 ik Praticolella . 1 x 1 | Amphicyclotus 2 1 2 Arionta : 3 .. | Cystopoma 2 wid we Lysinoe : : 1 1 1| Tomocyclus . 4 1 2 Oxychona 2 5 Choanopoma 2 2 ae Solaropsis aise 2 ... | Chondropoma 2 11 — Polygyra . = 1 2 | Helicina 13 10 6 Strobila 1 A ... | Schasicheila. 2 oad 1 Labyrinthus. by 5 a+ |Geres ; 2 a oe Otostomus . ve e2S 20 7 | Proserpinella 1 ae Bulimulus 6 5 2 (3) The Colombian Sub-region includes Colombia, New Grenada, Venezuela, Guiana, Ecuador, Peru, and Bolivia. It has XI COLOMBIA AND VENEZUELA Rn 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 such a 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 Fie. 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 Curacao. 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. 385 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 retnarkably 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 8 in Peru and Bolivia; Jsomeria 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 Menta — 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. Fic. 234. — Rhodea Two very remarkable forms belonging to the gamed aos» Pupidae, Anostoma (Fig. 154, p. 248) and Toii- gerus, occur in Venezuela, the metropolis. ho- dea, another very peculiar shell (Fig. 284), whose exact family XI THE GALAPAGOS — BRAZIL 357 position is uncertain, is pecuhar to New Grenada. The land operculates are few in number, and in Bolivia almost disappear. They belong principally to Neocyeclotus (of which 11 species occur in Venezuela and Colombia) and Helicina (10 species in the same district), besides the stragglers already mentioned from West Indian sources, and a few Cydopiorn: Bourcieria is a form of Helicina peculiar to Ecuador. Ampullaria, with Cera- todes, a pecuhar planorbiform sub-genus, and Hemisinus, form the bulk of the fresh-water operculates. Lhe Galapagos. — Thirty-four species of land Mollusca, all pecuhar, 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 Jesiotis, 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 resuit 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, Ds 169; von Ihering, Nachr. Deutsch. Malak. Gesell. 1891, p. 98. : 35 8 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. 233) and Strophochilus being pecul- iar. Bulimulus, though not so abundant as in Peru and Ecuador, has about 60 species, of Fic. 235. — Bulimulus which Navicula (Fig. 235) is the most remark- ce ee 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 separate 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 5. 036 _ odonto- part of Chili, from its arid and rainless climate, stomus pantagru- is unfavourable to the existence of land Mol- ees reat zs lusca. Bulimus (Borus) still has 3 or 4 species, and Bulimulus (Plectostylus 11, Scutalus 9, Peronaeus 7) is 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 Amphidoxra. Chilina, a singu- larly solid form of Limnaea (of which 8 sp., with a sub-genus Pseudochilina, occur in Chili), is peculiar to Chili, S$. 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 Limax 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 8. 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 S. and W. Australia, with the Caryodes of Tasmania, and the Leucotaenta and Clavator of Mada- gascar (which all may be related to Bulimus), together with the Placostylus of New Caledonia and the adjacent islands, reaching 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, 2thytida is a marked link between Africa and Austraha, while Streptaxis is equally so between S. America and Africa. As regards fresh-water Gasteropoda, Ampullaria is common to S. America and Africa, while Js¢dora is common to Africa, Australia, and New Zealand, but is altogether absent from S. 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 (Clanthina, 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°.1 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 hmited 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 £. 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. CN. 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 80 to 2750 fath., Arca glacialis at 25 to 1620 fath., Astarte compressa at 3 to 2000 fath., and Sero- bicularia longicallus at 20 to 2435 fath. Puncturella noachina has been found at 20 to 1095 fath., Natica groenlandica at 2 to 1290 fath., Rissoa tenuisculpta 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 papers in P. Z. §. 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, LIittorina, Nassa, Purpura, Strombus, Haliotis, Mytilus, Cardium, Solen; while among deep-water genera are Pleurotoma, Scissu- rella, Seguenzia, Dentalium, Cadulus, Limopsis, Nucula, Leda, Lima, and Axinus. 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 1878-76, 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 7’ravailleur (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 Hirondeile 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 Sarsti 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. x 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 profundorwm 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 890 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 775 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 hfe 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. 52° (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. 422° (Newhaven), surface temperature 52°, extreme range 30°. 364 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. . (1. Australian. 3 2. Boreal. C. Australian | 2. Neozealanian. A. Atlantic and | 3. Celtic. (1. Aleutian. Circumpolar | 4. Lusitanian. | 2. Californian. 5. West African. | 3. Panamic. 6. South African. TAGHETICAT | 4. RMS B. Indo-Pacifi 1. Indo-Pacific. | 5. Magellanic. Fiver | 2. Japanese. . Argentinian. 15 | 6 | 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 circumpolar 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 Avinoft 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 Celtie 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 gradual 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), Zrichotropis borealis Brod. (to the Dogger Bank), Margarita helicina Fabr. (to Yorkshire and Dublin Bay), JZ. groenlandica Chem. (western Scotland), Natica montacuti Forb. (to Cornwall), Trophon truncatus Str. (to Tenby), Chiton mar- moreus Fabr. (to Dublin Bay and Scarborough). Buceinwm undatum and Littorina 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 Turtoni 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 366 LUSITAINAN SUB-REGION CHAP. north than the southern coasts of the Channel, the west of France, and the Mediterranean. The Baltic, a sea specially lable 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 Ushant 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, Huthria, 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- biwm 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. 80° 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 ~ xu 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 ttle known. The principal genera are Cymbium, Pleurotoma, Marginella, Terebra, Mitra, Aygaronia, Murex, Cancellaria, Purpura, Pseud- oliva, Natica, Tellina, Lucina, Tugonia, Sehizodesma, 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 33 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 lst Natal species, which more prop- erly belong to the Indo-Pacific fauna. Of these 740, 323 are pecuhar, 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., WM. septangularis Mont., Cylichna cylindracea Penn., Pholas dactylus L., Solen marginatus Pult., Cultellus pellucidus Penn., Ceratisolen legumen L., Lutraria oblonga Chem., Tellina fabula Gmel., 7. 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 Mollusea 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 1K. A. Smith, P. Z. S. 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 Mollusea, 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 Philivpines 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 18; 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: Nautilus, 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 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.t. 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 verséd. Two Red Sea species (Mactra olorina Phil., Mytilus variabilis Ky.) 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. Ds dorso-lateral ; tentacular arms retrac- pocket into which the tentacu- tile; two first dorsal arms in the 4" atm is retracted. male hectocotylised ; gladius narrow, half as long as the body.— World-wide. Principal genera: Sepiola, dorsal mantle connected with the head by a broad cervical band, ventral mantle with the funnel by a ridge fitting into a groove; Rossia, dorsal mantle supported by a ridge, arms with never more than four rows of acetabula: Inioteuthis, Stoloteuthis, Nectoteuthis, and Promachoteuthis. Fam. 2. Sepiadariidae. — Fins not as long as the body, mantle united to the head on the dorsal side, fourth left arm in the male hectocotylised; no gladius. Principal genera, Sepadarium, Sepioloidea. — Chiefly Pacific Ocean. Fam. 3. Idioseptidae.— Fins very small, terminal; fourth pair of arms in the male hectocotylised, bare of suckers. The only genus, Idiosepion, with a single species CL. pyg- maeum Stp.) is from the Indian Ocean, and is the smallest known Cephalopod, measuring only about 15 mm. in length. Fam. 4. Loliginidae. — Body rather long, fins varying in size, tentacular arms partially retractile, gladius as long as the back, pointed in front, shaft keeled on the ventral side. — World-wide. Loligo proper has a pointed body with triangular posterior fins united behind; sessile arms with two rows of acetabula, L | 1 uvéw, Close the eyes; dis, sight; contrasted with Oigopsidae (oiyw, open). 390 DECAPODA CHAP. tentacular arms with four; fourth left arm hectocotylised at the tip ; funnel attached to the head. Other genera are Loliguncula, Sepioteuthis, and Loliolus. Belemnosepia, Beloteuthis, Leptoteu- this, and Phylloteuthis are fossil genera only, differing in the shape of the gladius. (b) Oigopsidae: cornea more or less open; species pelagic. Fam. 5. Ommastrephidae. — Body cylindrical, fins generally terminal, united together, regularly rhomboidal, sessile arms with varying number of rows of acetabula, mantle connexions elaborate; gladius horny, narrow lanceolate, with a hollow cone at the posterior end. — World-wide. Ommastrephes proper has a natatory web on the sessile arms ; the wrist of each club has a series of acetabula with correspond- ing cushions on the other wrist. In Thysanoteuthis (often made a separate family) the sessile arms have two rows of cirrhi, with lateral expansions of the skin; fins as long as the body. In Fic. 250.— Architeuthis princeps, Verr., E. America: /, Right fin; fw, funnel; /.c, fixing cushions and acetabula on the tentacular arms (¢, ¢). (After Verrill, x ds.) Architeuthis, to which belong the largest Cephalopoda known, the fins together are shaped like a broad arrow-head ; acetabula of sessile arms strongly denticulate ; tentacular arms very long, with equidistant pairs of acetabula and fixing cushions through- out their entire length, and a group of the same at the base of the club. The acetabula and cushions correspond on the oppos- ing tentacles, and enable them to pull together. Other genera are Dosidicus, Todarodes, Illex, Bathyteuthis and Mastigoteuthis. Fam. 6. Onychoteuthidae.— Body cylindrical, fins terminal or lateral, mantle-locking apparatus elaborate, tentacular arms very long, sessile or tentacular arms furnished with retractile hooks, gladius lanceolate, with a terminal cone.— World-wide. The prehensile apparatus of Cephalopoda reaches its maxi- mum of power and singularity in this family. In Onychia, Onycho- XIII DECAPODA 391 teuthis and Ancistroteuthis, the sessile arms have acetabula only, in Gonatus and Abralia they have hooks as well, while in Verania, Ancistrochirus and Enoploteuthis, the sessile arms have hooks only. The number of rows of hooks or acetabula varies with the different genera. Fam. 7. Chiroteuthidae.— Head nearly as large as the body; fins terminal, tentacular arms very long, sessile arms slightly webbed, acetabula denticulated; mantle-supports consist- ing of cartilaginous ridges on the mantle, which fit into corresponding depressions on the tunnel, gladius ex- panded at each end. — Atlantic Ocean. The six dorsal arms in Histioteuthis are united by a broad web, while in Histiopsis the web only reaches half way up the arm. In Chiroteuthis the tentacular arms have scattered sessile suckers throughout their whole length, and four rows of very long peduncu- late suckers on the clubs. Fam. 8. Cranchiidae.— Head small, body rounded, barrel-shaped, fins termi- nal, eyes often very large, sessile arms short, tentacular arms long, thread-like. — World-wide. Cranchia proper has the tentacular clubs finned, with eight rows of suck- ers, body sometimes covered with warty tubercles. Loligopsis has a very atten- uated body, with fins terminally united; some species are spotted with colour, Beer cree aeenadiles or have rows of tubercles on the ventral, 7, fins; ¢, ¢, tentacular side. TYaonius (Fig. 251) is doubtfully a™ms. (After Hoyle, x 3.) distinct from Loligopsis. Order Tetrabranchiata Cephalopoda with four branchiae and four kidneys; animal inhabiting the last chamber of an external multilocular shell ; 392 CEPHALOPODA — TETRABRANCHIATA CHAP. funnel consisting of two separate lobes; tentacles numerous, without suckers or hooks; no ink-sac. The shell consists of two layers, the outer being porcellanous, and the inner, as well as the walls of the chambers or septa, nacreous. The septa vary greatly in shape. In most of the Nautiloidea they are regularly curved, as in Nautilus, or straight, as in Orthoceras, but in the Ammonoidea they are often exceedingly complex. The edge of the septum, where it unites with the shell-wall, is called the suture, and the sutural line, which is not seen until the porcellanous layer is removed, varies in shape with the septum. The septa are traversed by a membranous tube known as the stphunele, which in Nautilus is said by Owen to connect ulti- mately with the pericardium. ‘The septal necks, or short tubular s&s. cerasa Scaphites with - the first whorls dis- united. Macrosca- 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.) sis Ail il my OU : { ( an | pl if united and not con- 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 Polit 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 light. 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 CHAP. XIV POLY PLACOPHORA 401 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 Fig. 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 coy- 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 Fic.261.—Valves of a Chiton inner layer which peparated 10 show the . various parts (anterior underlies the rest of valve uppermost): a, a, the substance of the articulamentum; Db, beak; : j, jugum; pil, pl, pleura; valve, and is called *% ¢, teomentum. 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 Lik the posterior valve the median Fic. 263.—First, fourth, and eighth area is very small, while the valves of a Chiton, showing 11, sculpture of the rest of the valve laminae 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 senus. 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 ecartilaginoid, 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- Fic. 264.—Girdles of various Chitonidae. A, Radsia sulcata Wood, x2) °8; Maugeria = granu- lata Gmel., x 3; C,Enoplochiton niger Barnes, x 3; D, Acanthochiton Fascicularis L., x 4; E, Tonicia fas- tigiata Sowb., x 4. ing backward; Chiton, Tonicia, Eudoxochiton, Craspedo- chiton. . D. Acanthoidea. — Insertion plates thrown forward; Sclero- chiton, Acanthopleura, Dinoplax, Middendorffia, Nuttal- lina, Arthuria, Phacellopleura. SECTION II. CHITONES IRREGULARES. — Posterior valve abnormal, or with a sinus behind. E. 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, Notoplax. 404 APLACOPHORA CHAP. H. Cryptoidea.— With double sutural laminae: Crypto- conchus, Amicula, Oryptochiton. Fic. 265.— Chitonellus fasciatus Quoy ; ant, anterior end. I. Chitonelloidea. — Posterior valve funnel shaped; laminae thrown forward; Chitonellus, Choneplacz. Sub-order 2. Aplacophora. — Animal vermiform, ioot absent, or a mere groove, cuticle more or less covered with spicules. Fic. 266. — Neomenia ; ; : carinata Tullb.: a, worm-like exterior being anus; gr, ventral que to adaptation to sur- groove; m, mouth. : 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. Neomeniidae.— Foot a narrow groove, intestinal tube without differentiated liver, kidneys with common exterior orifice, sexes united, ctenidia present or absent. Genera: Neomenia (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 Fic. O61. Chabradeeae 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 Vises al 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. 3. 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, Seutellastra, Ancistromesus (A. mexicana Brod., measures 8-14 in. long): Helcion, branchial circlet interrupted in front; Zryblidiwm (Ordovician). — (i1.) Nacellinae. —'Two developed laterals on each side, one anterior. Genera: Nacella, branchial circlet complete; Helcioniseus, bran- chial circlet interrupted in front. (6) RaAIPIDOGLOsSA (p. 225). — Ventricle of the heart trav- ersed by the rectum (except in Helicinidae), one of two ctenidia; Jaw in two pieces, radula long, marginals multipled, 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. Fissurellidae.— Two symmetrical ctenidia and kid- neys, visceral mass conical, shell conical, elevated or depressed, with a single anterior or apical slit 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, ps 26a) setae suridea, Clypidella. (i.) Fissurelli- dinae. Shell partly internal, otherwise as in (i.); central tooth broad, mantle more or less reflected over the shell, apical hole very wide. Genera: F%s- surellidaea, Pupillaea, Lucapina,Mega- tebennus, Macroschisma, Lucapinella. Gu.) Hmarginulinae. Shell usually Fic. 268. — Scutus australis Lam., wholly external, apex usually not re- Australia: m, m, mantle; sh, : ‘ ‘ shell. x 3. moved by perforation, sometimes with internal septum, anal tube in a narrow sht or sinus. Genera: Glyphis, externals of Fisswrella, but hole- callus truncated behind; Pwncturella (sub-genera Cranopsis and Fissurisepta), slit just anterior to the apex, a small internal septum ; Zezdora, large internal septum as in Crepidula: Emar- ginula, shell elevated, slit very narrow, on the anterior margin Cn 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; no operculum. Cretaceous . Single genus, Haliotis ; principal sub-genera Padollus, Teinotis. Fam. 38. Pleurotomariidae.— 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; TZ'rochotoma, shell trochiform, perfora- tion consisting of two nar- row holes united by a slit: Pleurotomaria, branchiae almost symmetrical, radula as above, shell variously spiral. In Pleurotomaria we have the case of a genus | : Fia. 269. — Pleurotomaria adansoniana Cr. and long supposed to be extinct. F., Tobago. x }. More than 1100 fossil species have been described, and within the last 38 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. Cocculinidae.— 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: Liotia, 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 (Hie, 182, p. 268). Silunan G.) Trochinae.— Frontal lobes present, lateral teeth (= side centrals) 5 only, no jaws, peristome incomplete. Prin- cipal genera: T'rochus (subg. Cardi- nalia, Tectus, Infundibulum, Clan- culus), Monodonta (subg. Diloma), Fic. 270. — Monodonta canali- Cantharidus (subg. Bankivia, Tha- ace Eeeean lotia), Gaza (subg. Microgaza), Cal- logaza, Bembix, Chlorostoma. (ii.) Gibbulinae. — Frontal lobes and jaws present, laterals often more than 5, peristome incomplete. Principal genera: (i6- bula (subg. Monilia, Aphanotrochus, Enida), Minolia, Circulus, Trochiscus, Livona, Photinula, Margarita, Solariella, Calli ostoma, Turcica, Basilissa, Euchelus (subg. Olivia, Perrinia). (ili.) 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: Umbonium, Hthalia, 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 Ga.) Phastanellinae.—Shell bulimoid, polished, not nacreous, coloured in patterns, aperture oval. Single genus, Phasianella (Fig. 271). Gi.) Zurbininae.— 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 ; Astralium, 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, Cyelocantha, Uvanilla, Cookia, Pomaulax, Pachypoma. (iii.) Cyclo- nematinae.—Shell nacreous, umbilicate, operculum conical outside, whorls scalari- form. Principal genera: Cyclonema, Hori- ostoma (?), Amberleya (Silurian to Lias). Cv.) 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. 188, p- 269) thick, calcareous, ae ae se 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), Vaticopsis (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 Reguienca, 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: Nerita (Fig. 18, p. 17); Neritina (chiefly brackish water and fluviatile), sub-genus Clithon, usually coronated with spines; Velates (Tertiary), Neritoma (Jurassic), Detanira (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. Helicinidae.—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 4II 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) PTENOGLosSA. — Radula with formula «#.o., 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. Scalariidae. — Shell long, turriculate, whorls often partly uncoiled, with longitudinal ribs and prominent lamellae, aperture circular, operculum spiral, corneous, animal carnivorous. Ordovician Principal genera: Scalaria, Hglisia, Elas- moneura (Silurian), Holopella (Silurian to Trias), Ales. (6) TAENIOGLOSSA. — Radula with normal formula 2.1.1.1.2, marginals sometimes multiphed (p. 228). Section I. PLatypopA.— Foot more or less flattened ven- trally. Fam. 1. Naticidae.— 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: atica, 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. 38. 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: T’richotropis, 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 Cncluding Crepipatella and Ergaea), shell shpper-shaped, with a large septum ; Calyptraea CGncluding 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 Fre. 272.— Two specimens of tO @ thin calcareous plate which closes Crepidula (marked a and the aperture like a valve; ventral side of ae eee: ora patie 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. Solariidae. — 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.) Solariinae. 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). (ii.) Toriniinae. Genera: Torinia, whorls usually rounded, operculum (Fig. 185) conically elevated, spiral externally, central tooth present, marginals few, edge pectinated; Omalazis. (iii.) EHuomphalinae, shell planorbiform, ee: whorls rounded. Genera: Huompha- yy. 973.— Solarium perspectivum lus, Ophileta, Schizostoma, Hecyliom- 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. Littorinidae.— 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: Inttorina (radula, Fig. 16, p. 20), Cremnoconchus (p. 16), Fossa- rina; Tectarius, shell tubercled or spinose; Azsella, 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. Terrestrial only. Cretaceous Ci.) Pomatiasinae, shell high, conical, longitudinally striated, operculum consisting of two laminae united together. Single genus, Pomatias. (il.) Diplommatininae, shell more or less pupiform, peristome thick- ened or reflected, often double. Genera: Diplommatina (subg., Nicida, Palaina, Pazillus, Arinia), shell dextral or sinistral, small, columella often denticulated; Opisthostoma (Fig. 208, p. AI4 MONOTOCARDIA — TAENIOGLOSSA CHAP. 309), last whorl disconnected, often reflected back upon the spire. (ill.) 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. (iv.) Cyclophorinae, shell turbinate or depressed, operculum corne- ous or calcareous. Genera: Alycaeus, Craspedopoma, Leptopoma, Lagochilus, Cyclophorus (Fig. 206, p. 806; including Diadema, Aulopoma, Ditropis, and others), Aperostoma Cncluding Cyrto- toma and others), Cyathopoma, Pterocyclus (sube., Myxostoma, Spiraculum, Opisthoporus, and Khiostoma (Fig. 180, p. 266), Cyclotus, Cyclosurus, and Strophostoma. Fam. 13. 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 (subg., Leonia, Tropidophora, Rochebrunia, Fic. 274.— Cyclostoma cam- Georgia, Otopoma, Lathidion, Revoilia), eee Pir, Mada- Qyelotopsis, Choanopoma (subg., Licina, Jamaicia, Ctenopoma, Diplopoma, Adam- stella), Cistula (subg., Chondropoma, Tudora), Omphalotropis (sube., Realia, Cyclomorpha), Hainesia, Acroptychia. Fam. 14. Actculidae.— 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: Truncatella (subg., Tahettia, 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: Rissoa (subg., Folinia, Onoba, Alvania, Cingula, Nodulus, Anaba- thron, Fenella, [ravadia, and others ), Scaliola (shell agglutinating fragments of sand, etc.), Azssomna (lip thickened, operculum with an apophysis as in Nerita), 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. 299); 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. Assimineidae.—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 Lnoplaz. 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. 25. 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 as in Vivipara. 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: Triforis, 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 AL (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. Nerinetdae.—Shell solid, long, sub-cylindrical, aperture channelled, columella and interior of whorls with continuous ridges, extending up the spire. Genera: Nerinea (Trias to Cretaceous), Aptyziella (Jurassic). Fam. 29. Melanitidae.— Border of mantle festooned, foot broad, with an anterior groove, penis present; radula closely re- sembling that of Cerithium; 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 (Eocene), Larina (?). Fam. 30. Plewroceridae.— Mantle edge not fes- tooned, no copulatory organ, otherwise like Melanii- dae; operculum with nucleus sub-marginal. Animal oviparous. Freshwater. Cretaceous Genera: ao. 975, — Me. Pleurocera (including Jo, Fig. 12, p. 16, Angi- lnia con- trema, Lithasia, Strephobasis), Goniobasis, Anculotus, As aaa Gyrotoma. Fam. 31. Pseudomelanitidae. —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. Coectdae.—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 A418 MONOTOCARDIA — TAENIOGLOSSA CHAP. Fam. 34. Vermetidae.— Visceral sac greatly produced, irregularly spiral, no copulatory organs (rvadula, 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 153, p. 248), a long fissure, or series of holes, runs along a considerable part of the shell, operculum with outer face Pa, Dera spiral, elevated showing thegradual FAM. 305. Strombidae.—F oot narrow, arched, formation of septa; metapodium greatly produced, snout long, eye a, apex; ap, aper- : - ture; ss, first sep- peduncles long, thick, eyes elaborate, siphon tum; ss’, second short, penis prominent, bifurcate; central tooth septum. (After de. ; : : Folin.) B, adult With strong median cusp, marginals falciform, ep oeeaee slender, edge more or less denticulate; shell ,kanama. x 10. : ‘ ; : 5 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); Pereiraea (Miocene), Pteroceras (Fig. 277; digitations of the outer lip very strong), Rostellaria (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. 37. 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 multipled). 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 419 the sides, channelled at each end, labium inflected ; no opercu- lum. Jurassic Genera: Ovula (including Amphiperas, Transovula, Cyphoma, Radius, Simnia), Pedicularia, Cypraea (with subg., Cypraeovula, Cypraedia, and Trivia), and KHrato. Fam. 39. Dolvidae. — 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 (sube., 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. Vritonidae. — 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., Epidromus, 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. 45. Oocorythidae.— Siphon short, foot broad, eyes absent, radula taenioglossate ; Fig. 278. — Pima Dus- shell buecinoid or cassidiform, operculum cor- sumieri Val., Philip- pines. xd. 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. Seguenziidae.— Radula taenioglossate, shell trochi- form, aperture channelled, columella twisted, operculum multi- spiral, nucleus central. Pliocene Single genus, Seguenzza. Fam. 46. Cheristidae.— 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. HretTERopopA. — 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,” z.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 Cartnaria, and entirely covered in Atlanta ; absent altogether in Firoloida. 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 A422 MONOTOCARDIA — GYMNOGLOSSA — RACHIGLOSSA CHAP. a very small spiral shell. Carinaria (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 Oxy- gyrus is nautiloid, with the Fic. 279.—Carinaria mediterranea Lam., spire concealed, no keel, Naples: a, anus; 7, branchiae; f, foot; 7, aperture dilated. testies fu mouths Zoemlss es 6) Coreg Toe 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 (subg., 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 423 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: (i.) Muricinae, nucleus of operculum sub-terminal ; 7'ro- phon, Typhis, Murex (with many subdivisions), Ocinebra Ginclud- ing Cerastoma, Vitularia,and Hadriania), Urosalpinx, Eupleura, Pseudomurea. (i.) Purpurinae, nucleus of operculum lateral ; Rapana Gncluding Latiaris), Purpura (with subg., Cuma, Lopas, Vexilla, and Pinaxia), Monoceros (including Chorus), Purpu- rotdea (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: Rhizochilus, Co- ralliophila, Leptoconchus, Magilus (Fig. 29, p. 75), Rapa. Fam. 8. Columbellidae. — (Radula, Fig. 125, p. 222.) Shell small, solid, fusiform, aperture narrow, canal short, outer lip thickened. Miocene Single genus, Columbella (subg., Nitidella, Anachis, Meta, Strombina, Atilia, Conidea, Amphissa, Mitrella, and others). Fam. 4. Nasstdae.— 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: Massa (with many sections), Amycla, Desmoulea, Cyclonassa, Canidia (subg., Clea and Nasso- donta), Dorsanum, Bullia (= Buccinanops, Fig. 62, p. 185), Truncaria. Fam. 5. @uccinidae. — 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 i. Chrysodomus (with sections Neptunea, Volutopsis, Pyrolofusus, 424 MONOTOCARDIA — RACHIGLOSSA CHAP. Jumala), subg., Sipho; Siphonalia (subg., Kelletia). Group ii. Tiomesus (= Buecinopsis). Group ii. Buccinum (Fig. 1B, p. 6; subg., Volutharpa, Neobuccinum). Group iv. Cominella, Triton- idea, Pisania, Huthria ; Anura (Miocene), Genea (Pliocene), Metula, Engina. 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), Fie. 280. — Turbinella pyr- Strepsidura (Eocene, subg., Whitneya), um Lam., Ceylon. x 3. : : Melapium, Fulgur (= Busycon, Fig. 150, p. 249, including Sycotypus), Melongena (subg., Pugilina, Myristica); Liostoma (Kocene), Hemifusus (subg., Megala- tractus), Ptychatractus, Meyeria. Fam. 7. Fasciolariidae.— 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 (including Sinistralia, Aptyxis, Troschelia), with subg., Serri- fusus (Cretaceous), Clavella (subg. Thersites), Fasciolaria, Latirus (subg. Polygona, Peristernia, Leucozonia, La- gena; Mazzalina (Eocene), Chascax). Fam. 8. Jlitridae.— Siphon rather long, with anterior appendages, eyes on the side of the tentacles, proboscis very long; radula variable, laterals Fc. 281.— Latirus (Leucozonia) ‘ : cingulatus Wood, Panama. 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 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 Principal genera: Crypto- ee ae Ai: 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 (?), Cystiseus, 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 Fg, 20; Olan go (subg Sia). : : “Fam. 12. Olividae. — 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, Principal genera: 426 MONOTOCARDIA — TOXOGLOSSA CHAP. XIV operculum present or absent. Cretaceous 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. Kocene Single genus, Terebra, with several sec- tions. Fam. 2. Conidae.— Eyes on outer side of tentacles, 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 (Eocene), Drillia (subg., Spirotropis), Bela, Mangilia (including Daphnella, Clathurella, and others), Halia. Fic. 284.—Terebra sub- ulata L., Ceylon. Tintricula 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. 7 285. — 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., Merica, 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 Fic. 286. — Illustrating the transition Fia. 287.—TIllustrating 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 in 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 (Siphonaria, 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 Limapontia 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. Seaphander has been seen to swallow Dentalium six at a time, and in six hours the shells of all were reduced to tiny fragments. Glawcus 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 1. TECTIBRANCHIATA : | © | Pleurobranchoidea | \ Siphonarioidea Opisthobranchiata ; 2. AscoGLossa | 3. NUDIBRANCHIATA . j Ciaaclen alee | | Holohepatica | A. PaOren sk ' Thecosomata rf | Gymnosomata 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. 334; P.Z. 8. 1836, p. 113; Arch. Zool. Exp. Gén. (3) i. 1898, p. 105. 430 TECTIBRANCHIATA CHAP. Actaeonina (Carboniferous), Cylindrites (Secondary strata), Actaeonella (Cretaceous). Fam. 2. Tornatinidae.— 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); Sabatia (Pliocene), Smaragdi- 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. Philinidae.—Shell completely internal, thin, shghtly 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. ApPLysIomIpEA. — 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. Aplysiidae.— Characters those of the section. Genera: Aplysia (Fig. 287 D), shell arched, flattened, animal large (the ‘sea hare”); Dolabella, shell sub-triangular (Fig. 286 IF) ; Dola- brifer, shell sub-quadrangular, not spiral ; Motarchus, shell micro- scopic, spiral; Phyllaplysia, body very depressed, oval, no shell. Section III. PLEUROBRANCHOIDEA.— 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: Plewrobranchus (Fig. 286 H), (?) Haliotinella, Pleurobranchaea, (?) Neda. Fam. 2. Runeinidae.—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. Stphonariidae.— Characters those of the section. Genera: Stphonaria (branchia as well as pulmonary sac), Gad- tnia (no branchia). These genera, hitherto placed among the Pulmonata, have been recently shown (see p. 19) to be modified Opisthobranchiata. Sub-order II. Ascoglossa.1— 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 (acxcs). 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 Cladohepatie Nudibranchs. 432 ASCOGLOSSA — NUDIBRANCHIATA CHAP. the Cladohepatie Nudibranchs, while the Pleurobranchidae form a somewhat similar link between the Holohepatic Nudibranchs and the other Tectibranchiata. Fam. 1. Oxynoeidae+— 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: Oxynoe (= Lopho- cercus), Lobiger. Fam. 2. Hermaeidae.— Body de- pressed, cerata in several rows, no branchiae, no shell. Genera: Hermaea, Phyllobranchus, Stiliger, Alderia. Fig. 288.—Radula of one of Fam. 3. Elysiidae.— Body depressed, cee 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: Lima- 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. Aeolidiidae.— 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-lke, 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 A33 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. Seyllaeidae.— 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, Phyllirrhee. 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, Pleurophyllidia. Fam. 10. Pleuroleuridae. — Animal resembling Pleurophyl- lidia, but without the branchial lamellae. Single genus, Plew- roleura. Fam. 11. Tritoniidae.— Body long, two rows of unequal arborescent cerata, rhinophores with ramose appendages, liver not prolonged into the cerata. Genera: Tritonia, 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 ZF 434 NUDIBRANCHIATA CHAP. Hexabranchus, Archidoris (Fig. 289), Discodoris, Diaulula, Cadlina, Centrodoris, Platydoris, Chro- 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. Fam. 3. Phyllidiidae.— Body oval, depressed, leathery, a ring of branchial lamellae, only interrupted by the head and genital papilla, under the pallial edge, oral aperture pore-shaped, suc- Fre. 289.— Doris (Archidoris) torial, no radula. Genera: Phyllidia, tuberculata L., Britain: ¢, Fyyeria. Bergh unites this and the anus; 67, branchiae sur- : ; ; rounding the anus; 7, male preceding family in the group Porosto- Soe rh, rh, rhinophores. > 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 sunple, 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 folate, 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 ay, a O? OO aa on ed 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. 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 ‘wines ” 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. THECOSOMATA. — 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: Jzmacina, shell helicoid, deeply umbilicated (L. 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.— Ilustrations of Pteropoda Thecosomata: A, Limacina australis Eyd.; B, Cleodora cuspidata Bose. (shell only); C, Cuvierina columnelia Rang; D, Creseis virgula Rang ; E, Clio balantium Rang ; J, f, fins ; 7, 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, sightly 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 Hyalocyliz also belong to this group. Fam. 3. Cymbuliidae. — Vest (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 formidable 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: Dexvo- branchaea, no posterior gill, hook-saes short; Spongiobranchaea, posterior gill circular; Pnewmoderma, gill tetraradiate, hook- sacs long. Fam. 2. Olionopsidae. — 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. 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 Gaudichaudt Soul.; 7, f;, finss h.s, h.s, hook- sacs; l.f, lobe of the foot; s, 5s, suckers; 0, pos- terior genital orifice: “t.2 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 (=Hurybia) 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 | AML Fee iie ees organ a acne 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. 38. Amphibolidae.— A pulmonary lacie ely side of Fic. 292. — Examples of the Azriculidae: neck, eyes almost pedunculate, A, Auricula Judae Lam., Borneo; B, shell turbinate, rudely sculpt- Scarabus Lessoni Blainv., E. Indies; C, Cassidula mustelina Desh., N. Zea- ured, operculate.—Recent. land; D, Melampus castaneus Mihlt., Genus, Amphibola (Fig. 293) : = Pacific ; E, Pedipes quadridens Pir., ; amalca. subg. Ampullarina. Fam. 4. Limnaeidae.— 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, Erinna, Lantzia, Pompholyx, Choanomphalus (with Carinifex). (iii.) 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. 285); shell sinis- tral, lustrous. Jurassic Genera: Physa, Aplecta. Fam. 6. Chilinidae. — Lobe of pulmonary sac large, tentacles broad; shell ventricose, rather solid; columella plicate. Miocene Fie. 293.—Amphibola Single genus, Chilina. avellana Chem. 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 simple plate, internal), may be simple flattered spaces or may be broken up into definite channels, as in Lingula (Fig. 815). It seems not improbable that the body cavity fluid is aerated through the thin inner layer Fig. 315. — View of the inner side of the ane. of a valve of Lingula anati- Running along the base of each arm Jera (after Frangois),toshow are two canals, a small one at the base the definite arrangement of : the channels in the mantle: Of the tentacles, which we may term a, position of mouth; 6,posi- the tentacular canal, and a larger tion of anus. . one, the canal of the lip. The former sends a prolongation into each tentacle. The latter is, ac- cording to Blochmann, a closed canal in Crania, Lingula, Rhyn- SS AA [4 Ag \ yy) 2p $26 o i \Whal \ ares Sw e ASS Xv THE HEART 473 chonella, and others; but according to Joubin,' it communicates in Crania at one point with the tentacular canal. It is probably originally a part of the body cavity. Blochmann? states in very definite terms that in Crania neither the large canal nor the small canal communicates with the general body cavity, but he admits that in Lingula the small canal opens into that space. The Circulatory System The details of the discovery of the central circulatory organ of Brachiopods form a curious and instructive chapter in the history of modern morphological inquiry. Hancock, in his monograph on the group, described and figured on the dorsal surface of the alimentary canal a well-developed heart, which had been previously noticed by Huxley, who first showed that the organs which up to his time had been regarded as hearts were in reality excretory organs. In connexion with this heart Hancock described numerous arteries, distributed to various parts of the body. The observers who have written upon the anatomy of Brachiopods since Hancock’s time, in spite of the fact that they had at their disposal such refined methods of research as section cutting, which was quite unknown at the time his monograph was written, have almost all failed to find this circulatory system, and many of them have been tempted to deny its existence. Blochmann,® however, in the year 1885 stated that he had found the heart, and had seen it pulsating in several species of Brachiopoda which he had rapidly opened whilst alive. Joubin has also described it in large specimens of Waldheimia venosa, and recently Blochmann has published a detailed account of his work on this subject. Both these authors describe the heart as a vesicle with muscular walls, situated dorsal to the alimentary canal. From this, according to Bloch- mann, a vessel —the branchio-visceral of Hancock —runs forward as a triangular split in the dorsal mesentery supporting the alimentary canal. This vessel divides into two at the oeso- phagus, and passing through some lacunae in the walls of this 1 «* Recherches sur |’ Anat. des Brachiopodes Inarticules,’’ Arch. Zool. Exp. (2), Tome iv., 1886. 2 ‘* Untersuchungen tiber den Bau der Brachiopoden,”’’ Jena, 1892. 3 ‘* Vorliufige Mittheilungen iiber Brachiopoden,”’ Zool. Anz. Bd. viii. 1885. 474 RECENT BRACHIOPODA CHAP. tube, opens into the tentacular canal, and consequently supplies the tentacles with blood. These two canals which diverge from the median artery are connected ventrally by a vessel which runs below the oesophagus; the latter is therefore surrounded by a vascular ring. Blochmann also describes two pairs of vessels that were seen and figured by Hancock. A pair of these pass over the gastro-parietal mesenteries and into the dorsal mantle sinus, the second pair pass over the ileo-parietal mesenteries and into the ventral mantle sinus; each of these four arteries runs to one of the four generative glands, which, as is so usually the case in the animal kingdom, have thus a specially rich blood supply. _ If this description should prove to be correct, the vascular system of Brachiopods shows a striking resemblance to that of the closed vascular system of the unarmed Gephyrea, except that the former group has specialised genital vessels. The blood is colourless. Joubin’s description of the vascular system of W. venosa differs in some respects from that of Blochmann. He regards the heart as collecting the lymph which it receives from numerous lacunar spaces in the walls of the alimentary canal, and distributing it through various vessels, which in the main correspond with those of Blochmann, and which run both to the “arms” and to the generative glands. The latter vessels, however, open freely into the body cavity, and the fluid which is forced out from their openings freely bathes the organs found in the body cavity. Whichever of these accounts should prove to be more closely in accordance with the facts, there is little doubt that in addition to the true blood there is a corpusculated fluid in the body cavity which is to some extent kept in motion by the ciliated cells that lne its walls. The Excretory Organs The excretory organs (kidneys) which were at one time regarded by Cuvier and Owen as hearts, are typical nephridia — that is to say, they are tubes with glandular excretory walls which open at one end by a wide but flattened funnel-shaped opening into the body cavity, and at the other end by a circular pore to the exterior (Fig. 314). In Rhynchonella, where there are two pairs of these tubes, —the only evidence that the group presents of any metameric repetition of parts,—the inner XVII TELE eSrAIK 475 ends of the anterior pair are supported by the gastro-parietal mesenteries, and those of the posterior pair by the ileo-parietal mesenteries. In all other Brachiopods the posterior pair alone exists. The external opening of these nephridia is near the base of the anus; in Cistella it is at the bottom of a brood-pouch formed by the tucking in of the body wall in this neighbour- hood, and in this brood-pouch the eggs develop until the larval stage is reached. The walls of these nephridia are lined by ciliated cells, amongst which are some excretory cells, in which numerous brown and yellow concretions are to be seen; these are probably the nitrogenous excreta of the animal, and pass out of the body, being washed away by the stream of water which is constantly passing between the shells. As in so many other animals, the nephridia act as genital ducts, and through them the ova and spermatozoa, which break off from the genital glands and fall into the body cavity, find their way to the outer world. The Stalk and Muscles The body cavity of a Brachiopod is traversed by several pairs of muscles, which are very constant in position, and whose con- traction serves to open and close the shell, to move the animal upon its stalk, and to govern the movements of the arms. The stalk is absent in Crania, and the members of this genus are attached to: the rocks on which they are found by the whole surface of their ventral valve. In Lingula (Fig. 315) the stalk is long and hollow, containing what is probably. a portion of the body cavity, surrounded by muscular walls. Lingula is not a fixed form, but lives half-buried in the sand of the sea-shore (Fig. 821). Discina, the other member of the Ecardines, has a peduncle which pierces the ventral valve and fixes the animal to its support. Amongst the Testicardines, Thecidium is also fixed to its supports by the surface of its ventral valve; the other genera, however, are provided with stalks, which, being the means of the fixation of the animals, become at the same time the fixed points upon which their very limited movements can be effected. The stalk protrudes through the notch or aperture at the posterior end of the ventral 476 RECENT BRACHIOPODA CHAP. valve, and it probably belongs to the ventral side of the body. It is in (stella, and doubtless in other genera, in close organic connexion with both valves, and it seems to consist of an un- usually large development of the supporting tissue which occurs so frequently in the body of Brachiopods. The surface of the peduncle is produced into several irregularities and projections which fit into any depressions of the rock upon which the animal is fixed. In Cistella there are four pairs of muscles, two connected with opening and closing the shell, and two with the movement of the body upon the stalk (Fig. 314). The most considerable of these muscles are the two occlusors, which have their origin, one on each side of the middle line of the dorsal valve, and their insertion by means of a tendon into the ventral valve. In the species in question each of these muscles arises by a double head, the two muscles thus formed probably representing the anterior and posterior occlusors of other forms. The contraction of these muscles undoubtedly serves to close the shell, which is opened by a small pair of divaricators arising from the ventral valve, and inserted into a portion of the dorsal shell which is posterior to the axis of the hinge. Contraction of these muscles would thus serve to approximate the posterior edges of the valves and divaricate the anterior edges and thus to open the shell. The adjustors are four in number, a ventral pair running from the ventral valve to be inserted into the stalk, and a corre- sponding dorsal pair from the dorsal valve. The simultaneous contraction of either pair would tend to raise the valve, whilst the alternate contraction of the muscles of each side would tend to rotate the shell upon the peduncle. The muscles of Wald- heimia flavescens are shown in Fig. 329, and described briefly on p. 502. The muscles of the Ecardines differ from those of the Tes- ticardines inasmuch as they do not terminate in a tendon, but the muscle fibres run straight from shell to shell. They are also more numerous. In Crania there is an anterior and a posterior pair of occlusor muscles, and two pairs of oblique muscles, which seem when they contract together to move the dorsal shell forwards, or when they contract alternately to slightly rotate it. In this genus there are also a pair of pro- XVII THE MUSCULAR SYSTEM 477 tractors and a pair of retractors, and two levators of the arms, whose function is to draw forward or retract the arms, and an unpaired median or levator ani muscle. In addition to these bundles of muscles there are certain muscles in the body wall, and it seems probable that by their contraction, when the adductors are relaxed, the body may become somewhat thicker and the valves of the shells will slightly open. In Lingula (Fig. 322) the muscular system is more com- Fic. 316. — A semi-diagrammatic figure of the muscular system of Crania (after Blochmann): a, anterior occlusor; b, poste- rior occlusor; ¢c, superior ob- lique; d, inferior oblique; e, retractor of the arms; /, ele- vator of the arms; g, protractor of the arms; /, unpaired me- dian muscle. The dorsal valve is uppermost. plicated; in addition to the anterior (=anterior laterals) and posterior (=centrals) pairs of occlusors, there is a single divari- cator (= umbonal), whose contractions in conjunction with those of certain muscles in the body wall press forward the fluid in the body cavity, and thus force the valves of the shell apart; and there are three pairs of adjustor muscles. ‘These latter are called respectively the central (= middle laterals), external (= external laterals), and posterior (= transmedians ) adjustors, whose action adjusts the shells when all contract together, and brings about a certain sliding movement of the shells on one another when they act independently of each other.! 1 Hancock’s nomenclature is here used. The corresponding names used by King and Brooks are placed in brackets. Their nomenclature is used by many palaeontologists, and is adopted in Fig. 322. 478 RECENT BRACHIOPODA CHAP. The Nervous System The nervous system of Brachiopods is not very clearly understood, and there are considerable discrepancies in the accounts of the various investigators, even when they are dealing with the same species. So much, however, seems certain, that there is a nervous ring surrounding the oesophagus, that this ring is enlarged dorsally, or, in other words, near the base of the lip, into a small and inconspicuous dorsal ganglion, and again ventrally or just behind the base of the tentacles into a ventral or sub-oesophageal ganglion. The latter is, contrary to what is usual in Invertebrates, of much larger size than the supra-oesophageal ganglion, but like the last named, it has re- tained its primitive connexion with the ectoderm or outermost | layer of the skin. Both ganglia give off a nerve on each side which runs to the arms and along the base of the tentacles and lips. The sub-oesophageal ganglion also gives off nerves which supply the dorsal and ventral folds of the mantle, the muscles, and other parts. The modified epithelium in connexion with the ganglia may possibly have some olfactory or tactile function, but beyond this the Brachiopoda would appear to be devoid of eyes, ears, or any other kind of sense organs,—a condition of things doubtless correlated with their sessile habits, and with the presence of a bivalved shell which leaves no part of their body exposed. The Reproductive System The majority of Brachiopods are bisexual, and many autho- rities regard the separation of sex as characteristic of the group ; on the other hand, Lingula pyramidata is stated to be herma- phrodite, and it is not impossible that other species are in the same condition. The generative organs are of the typical sort, that is, they are formed from modified mesoblastic cells lining the body cavity. These cells are heaped up, usually in four places, and form the four ovaries or testes as the case may be (Fig. 314). The generative glands usually le partly in the general body cavity and partly in the dorsal and ventral mantle folds, two on each side of the body. Along the axis of the heaped-up cells XVII DEVELOPM ENT 479 runs a blood-vessel, which doubtless serves to nourish the gland, the outer surface of which is bathed in the perivisceral fluid. Every gradation can be found between the ripe generative cell and the ordinary cell lining the body cavity. When the ova and spermatozoa are ripe they fall off from the ovary and testis respectively into the body cavity, thence they are conveyed to the exterior through the nephridia. The ova in certain genera, such as Argiope, Cistella, and Thecidium, develop in brood- pouches which are either lateral or median involutions of the body wall in the neighbourhood of the external opening of the nephridia; they are probably fertilised there by spermatozoa carried from other individuals in the stream of water which flows into the shell. In other species the ova are thrown out into the open sea, and their chances of meeting with a sperma- tozoon is much increased by the gregarious habits of their sessile parents, for as a rule considerable numbers of a given species are found in the same locality. The Embryology We owe what little we know of the Embryology of the group chiefly to Kowalevsky,! Lacaze-Duthiers,2? and Morse.? The Russian naturalist worked on Cistella (Argiope) neapolitana, the French on Thecidium, and the American chiefly on Terebratulina. Although this is not known with any certainty, it seems probable that the eggs of Brachiopods are fertilised after they have been laid, and not whilst in the body of the mother. The spermatozoa are doubtless cast out into the sea by the male, and carried to the female by the currents set up by the cilia clothing the tentacles. In Thecidium, Cistella, and Argiope the first stages of devel- opment, up to the completion of the larva, take place in brood- pouches; in Terebratulina the eggs pass out of the shell of the mother and hang in spermaceti-white clusters from her setae and on surrounding objects. In the course of a few hours they become ciliated and swim about freely. The brood-pouch in 1 Development of the Brachiopoda, 1875 (Russian), 2 «¢ Histoire de la Thécidie,’’? Ann. d. Sci. Nat., Sér. 4, vol. xv., 1861. 3 *¢On the Early Stages of Terebratulina septentrionalis,’’? Mem. Boston Soc. Nat. Hist., vol. ii., 1869. ‘*On the Development of Terebratulina,’’ Zbid. vol. lila, L&do: 480 RECENT BRACHIOPODA CHAP. Thecidiwm is median, in the convex lower shell, in Cistella it is paired, and arises by the pushing in of the lateral walls of the body in the region just behind the horse-shoe-shaped tentacular arms; the renal ducts, which also serve as oviducts, open into these lateral recesses. In the female Thecidiuwm (Fig. 317) the two median tentacles which lie just behind the mouth are enlarged and their ends somewhat swollen; they are bent back into the brood-pouch, and to them the numerous larvae are attached by a short fila- ment inserted into the second of the four segments into which the larva is divided. In (%istella a similar filament attaches the larvae to the walls of the brood-sac ; thus they are secured from Fic. 317. — Brood-pouch of Thecidium mediterraneum. (After Lacaze- Duthiers.) Part of the wall of the pouch has been removed to show the clusters of larvae. 1. Mouth, overhung by lip. 2. One of the two median ten- tacles which are enlarged and modified to bear the larvae. 3. Wall of brood-pouch into which the median tentacles are folded. 4. Larva attached to the swollen end of the tentacles. being washed away by the currents constantly flowing through the mantle cavity of the mother. In Cistella the larva consists at first of two segments, but the anterior one divides into two, so that in the free swimming larva we find three segments, the hindermost somewhat longer and narrower than the others and destined to form the stalk. About the time of the appearance of the second segment four red eye-spots arise in the anterior segment, which tends to be- come constricted off from the others, and may now be termed the head. It gradually becomes somewhat umbrella-shaped, develops cilia all over its surface and a special ring of large cilia round its edge. In the meantime the second or mantle segment has grown down and enveloped the stalk, and four bundles of setae have XVII HABITS OF LARVAE 481 arisen from its edge. In this stage the larva leaves its mother’s shell and swims out into the world of water to look for a suit- able place on which to settle down. This is the only stage in the life history of a Brachiopod when the animal is locomotor, and can serve to spread its species. The extreme minuteness of the larva and the short time it spends in this motile condition probably accounts for the fact that Brachicpods are extremely localised. Where they do occur they are found in great numbers, rocks being often almost covered with them, but they are not found over large areas. When viewed under a microscope the larvae seem Y Tir, | I mT ai TANK A fl M\\\ ANY | Wy Fic. 318.— Young larva of Cistella neapolitana, showing three _ seg- ments, two eye-spots, Fig. 319.— Full-grown larva of Cis- and two bundles of tella neapolitana, with umbrella- setae. (After Kowa- shaped head, ciliated. (After levsky.) Kowalevsky.) to be moving with surprising rapidity, but judging from the analogy of other forms, it seems doubtful if they swim a yard in an hour. Frequently the larva stands on its head for some time, as if investigating the nature of the rocks on which it may settle; it is extremely contractile, turning its head from time to time, and seldom retaining the same outline for any length of time; the setae are protruded, and at times stick out in every direction ; they are possibly defensive in function. When fully stretched out the larva is about } mm. long, but it frequently shortens its VOL. III 21 482 RECENT BRACHIOPODA CHAP. body to two-thirds of this length. The larvae are of a pinkish red colour, with eye-spots of ruby red. Their colour renders them difficult to discern when they are swimming over the red coralline rocks upon which they frequently settle. After swim- ming about for a few hours the larva fixes itself finally, apparently adhering by some secretion produced by the stalk seoment. ‘The folds of the second or body segment then turn forward over the head, and now form the ventral and dorsal mantle folds; these at once begin to secrete the shell on their 60 564 aeQq qoute Fic. 520. — Stages in the development of the larva of Terebratulina septentrionalis. (After Morse.) The youngest larva has two segments, a third then appears, the larva then fixes itself, and the second segment folds over the first and develops bristles round its edge. outer surfaces. The head with its eye-spots must be to some extent absorbed, but what goes on within the mantle is not accurately known. The setae drop off and the tentacular arms begin to appear as a thickening on the dorsal lobe of the mantle. They are at first circular in outline. The various changes which the larva passes through are well illustrated by Morse for Tere- bratulina, which spawns at Eastport, Me., from April till August. The different stages are represented in outline in Fig. 320, taken from his paper. | Habits There is little to be said about the habits and natural history of the Brachiopoda. When once the larva has settled down, the animal never moves from the spot selected; occasionally it may rotate slightly from side to side on its stalk, and from time to time it opens its shell. As so frequently is the case with sessile animals, the sense organs are reduced to a minimum, the eyes of the larva disappear, and the only communication which the XVII animal has with the world around it is by means of the currents set up by the cilia on the tentacles. In spite of the absence of any definite eyes, Thecidium, according to Lacaze- Duthiers, is sensitive to light ; he noticed for instance that, when his shadow fell across a number of these animals he was watching in a vessel, their shells, which had been previously gaping, shut up at once. In Cistella the tentacles can be pro- truded from the open shell, and in Rhyn- chonella the spirally-coiled arms can be unrolled and extruded from the shell, but this does not seem to have been observed in other genera, with the possible ex- ception of Lingula. The food of these animals consists of minute fragments of animal and vegetable matter, a very large proportion of it being diatoms and other small algae. Lingula differs markedly from the other members of the group, inasmuch as it is not firmly fixed to a rock or some such body by a stalk or by one of its valves, but lives in a tube in the sand. Some recent observations of Mons. P. Frangois! on living specimens of Lingula anatifera which he found living in great numbers on the sea- shore at Nouméa in New Caledonia may be mentioned. The presence of the animal is shown by a number of elongated trilobed orifices which lead into the tube in which the Lingula lives. The animals, like most other Brachi- opods, live well in captivity, and he was able to watch their habits in the aquaria HABITS OF LINGULA Fig. 521. — Figures illustrating the tubes in which Lingula anatifera lives. The upper figure is a view of the tri- lobed opening of the tube. The lower figure shows the tube in the sand laid open and the animal exposed. The dotted line indicates the position of the body when retracted. The darker por- tion is the tube of sand ag- glutinated by the secretion of the stalk. (After Francois.) 1“‘Choses de Nouméa,’’ Arch. d. Zool. exp. et gen., 2nd ser., vol. ix., 1891. 484 RECENT BRACHIOPODA CHAP. of his laboratory. The Lingula place themselves vertically; the anterior end of the body just reaches the level of the sand; the three lobes into which the orifice of the tube is divided cor- responding with the three brushes of setae which project from the anterior rim of the mantles. These setae are described by Morse as projecting in the form of three funnels; currents of water are seen continually passing in at the side orifices and out through the central. The tube consists of two portions: an upper part, which is flattened to correspond with the flat shape of the body, and a lower part, in which the stalk hes. The upper part is lined with a layer of mucus, but the sand is not glued together to form adefinite tube. The lower part of the stalk, or the whole when the animal is contracted, is lodged in a definite tube composed of grains of sand agglutinated by mucus, probably secreted from the walls of the stalk. At the least sign of danger the stalk is contracted violently, and the body is withdrawn to the bottom of the upper portion of the tube. The rapid retreat of the animal is followed by the collapse of the sand at the mouth of the tube, and all trace of the presence of the Lingula is lost. The shells of this species are frequently rotated through a small angle upon one another, a movement which is prevented in the Testicardines by the hinge. In very young transparent specimens Frangois was able to observe the movements of the fluid in the system of tubules which penetrate the mantle; these tubules are figured by him, and Fig. 815 is taken from his illustration. Davidson in his Monograph on the British Fossil Brachi- opoda states that the largest “recent Brachiopod which has come under my notice is a specimen of Waldheimia venosa Solander, measuring 38 inches 2 lines in length, by 2 inches in breadth, and 1 inch 11 lines in depth.” It was found in the outer harbour of Fort William, Falkland Islands, in 1843. A specimen of Terebratula grandis from the Tertiary deposits, how- ever, exceeds this in all its dimensions. Its length was 44 inches, its breadth 3 inches 2 lines, and its depth 2 inches 2 lines. Distribution in Space Brachiopods are very localised; they live in but few places, XVII VERTICAL DISTRIBUTION 485 but when they are found they usually occur in great numbers. During the cruise of the Challenger, dredging was conducted at 361 stations; at only 38 or 89 of these were Brachiopoda brought up. Mr. Cuming, quoted by Davidson, records that after a great storm in the year 1836, he collected as many as 20 bushels of Lingula anatifera on the sea-shore at Manilla, where, he relates, they are used as an article of food. It has been suggested above that their abundance in certain localities is due to their limited powers of locomotion, which are effective but for a few hours, the larva being, moreover, so minute that unless borne by a current it could not travel far from its parent. When once settled down it has little to fear from the attacks of other animals. The size of its shell relative to its body would deter most animals from regarding it as a desirable article of food, and as far as is known at present the Brachiopoda suffer but little from internal parasites, the only case I know being a minute parasitic Copepod belonging to a new and as yet unnamed genus which I found within the mantle cavity of Cistella (Argi- ope) neapolitana in Naples. Their slight value as an article of diet has doubtless helped to preserve them through the long periods of geological time, through which they have existed apparently unchanged. Two of the recent genera of the family Lingulidae, Lingula and Glottidia, are usually found between tide-marks or in shallow water not exceeding 17 fathoms. Discina is also found about the low-tide level, but one species at any rate, Discinisea atlan- tica, has been dredged, according to Davidson, “at depths rang- ing from 690 to nearly 2425 fathoms.” Their larvae frequently settle on the shells of their parents, and thus numbers of over- lapping shells are found clustered together. Crania is usually dredged from moderate depths down to 808 fathoms, adhering to rocks, lumps of coral, stones, and shells. Of the Testicardines, Terebratula Wyvillet has probably been found at the greatest depth, 7z.e. 2900 fathoms, in the North Pacific. It is interesting to note that its shell is glassy and extremely thin. The Brachiopoda are, however, as a rule, found in shallower water; they abound up to a depth of 500 or 600 fathoms, after which they rapidly diminish with increasing depth. About one-half the named species occur at a depth of less than 100 fathoms. 486 RECENT BRACHIOPODA CHAP. The vertical range of depth of certain species is great; Tere- bratula vitrea is recorded from 5 to 1456 fathoms, 7. Wyvillez from 1035 to 2900 fathoms. This is to some extent expli- cable since, after a certain depth has been reached, many of the external conditions, such as absence of temperature and light, must remain constant even to the greatest depths of the ocean. i The area of the ocean explored by dredging forms such an infinitesimal fraction of the whole, that it seems superfluous to consider the horizontal distribution of Brachiopods. A few facts may, however, be mentioned. Certain species, as Terebra- tula vitrea, T. caput serpentis, Waldheimia cranium, Megerlia truncata, and Discinisca atlantica, have a very wide if not cos- mopolitan distribution. The second of the above named extends as far north as Spitzbergen, and as far south as Kerguelen Island. Many species are, on the other hand, very localised, and have hitherto only been found in one place. A very con- siderable number of these have been dredged off Japan and Korea, and this region may be to some extent regarded as the headquarters of the group. The following species have been obtained within the limits of the British Area, as defined by Canon Norman, who has been good enough to revise the list, which is founded on that drawn up by Davidson in his Challenger Report. Their range of bathymetric distribution is given in the column on the left. Depth in Fathoms 0 to 1180. Terebratulina caput serpentis Lin. Oban, and off Cumbrae Islands, Loch Torridon, Scotland, off Belfast 8to 25. Terebratula (Gwynia) capsula Jeff. Belfast Bay, E. and S. coast of Ireland, Plymouth, Weymouth, and Guernsey 5 to 690. Waldheimia cranium Miiller . . North British seas. Off Shet- land 75 to 725. Waldheimia septigera Lovén . . North British seas. Off Shet- land 20 to 600. Terebratella spitzbergenensis Dav. N.N.W. of Unst, Shetland 18 to 364. Argiope decollata Chemnitz . . Two miles east of Guernsey 20to 46. Cistella cistellulaS. Wood . . Shetland, near Weymouth, S. coast of England 650 to 1750. Atretia gnomon Jeff. . . . . W. of Donegal Bay in 1443 faths. Between Ireland and Rockall, in 13850 faths. XVII CLASSIFICATION AND AFFINITIES 487 Depth in Fathoms 10 to 690. Rhynchonella psittacea Gmelin . Shetland and near Dogger Bank. This species is possibly fossil as well as recent 3 to 808. Crania anomala Miiller . . . Loch Fyne, North of Scotland 690 to 2425. Discinisca atlantica King. . . W.of Donegal Bay in 1366 faths., W. of Ireland in 1240 faths., off Dingwall Bay Classification The table of classification here appended is that suggested by Mr. Davidson in his Monograph on the Recent Brachiopoda. I. TESTICARDINES Family A. TEREBRATULIDAE. Thisincludes the majority of genera and of species, the latter, without counting uncertain species, amounting to sixty-eight. Examples: Terebra- tula, Terebratella, Terebratulina, Waldheimia, Megerlia, Argiope, Cistella. B. THECIDIIDAE. This family contains one genus, Thecidium, with two species. C. RHYNCHONELLIDAE. This family is made up of eight species, six of which belong to the genus Rhynchonella, and two to Atretia. Il. ECARDINES D. CRANIIDAE. This family comprises the four species of Crania. KE. DiIscrniDAeE. This family contains one species of Discina and six of Discinisca. F. LINGULIDAE. This family consists of eight species of Lingula and three of Glottidia. It is impossible to come to any satisfactory conclusion as to the position of the group Brachiopoda with relation to the rest of the animal kingdom. They have, in accordance with the views of various investigators, been placed in close connexion with many of the large groups into which the Invertebrates are spht up. The Mollusca, the Tunicata, the Polyzoa, the Chaeto- poda, the Gephyrea, and of recent times such isolated forms as Phoronis and Sagitta, have all in turn had their claims advanced of relationship to this most ancient group. As far as Iam ina position to judge, their affinities seem to be perhaps more closely with the Gephyrea and with Phoronis than with any of the other 488 RECENT BRACHIOPODA CHAP. XVII claimants; but I think even these are too remote to justify any system of classification which would bring them together under a common name. Investigation into the details of the embry- ology of the group, more especially into that of the Ecardines, might throw some light on this subject, and it is much to be desired that this should be undertaken without delay. That the group is a most ancient one, extending from the oldest geological formations, we know, that the existing members of it have changed but little during the vast lapse of time since their earliest fossil ancestors flourished, we believe; but we are in almost total ignorance of the origin or affinities of the group, and we can hardly hope for any light on the subject except through embryological research. BRACHIOPODA PAGE If PALAEONTOLOGY OF THE BRACHIOPODA BY F. R. COWPER REED, B.A., F.G.S. Trinity College, Cambridge CHAPTER XVIII PALAEONTOLOGY OF THE BRACHIOPODA INTRODUCTION — DIVISION I. ECARDINES — EXTERNAL CHAR- ACTERS — INTERNAL CHARACTERS — DIVISION II. TESTI- CARDINES — EXTERNAL CHARACTERS — INTERNAL CHAR- ACTERS — SYNOPSIS OF FAMILIES — STRATIGRAPHICAL DISTRIBUTION — PHYLOGENY AND ONTOGENY Introduction T' wide distribution and vast abundance of the Brachiopoda throughout the whole series of geological formations make this group of especial importance to the student of the past history of the earth; and the zoologist must always regard the fossil forms with peculiar interest, because they not only largely out- number the living representatives, but comprise numerous extinct genera, and even families, exhibiting types of structure and char- acters entirely absent in the modern members of the group. It is a most fortunate circumstance that the excellent state of preservation in which we frequently find them, and the immense amount of material at our disposal, enable us to determine with accuracy and certainty the internal characters of the shells in the great majority of cases. But it is only since the beginning of the present century that our knowledge of the anatomy of the soft parts of the living animal has rendered any tracing of homologies possible. In the case of features in fossil extinct types the inter- pretation must be to some extent doubtful. Barrande, Clarke, Davidson, Hall, King, Oehlert, Waagen, de Verneuil, and a host of other workers have contributed to the information which we now possess; and their works must be consulted for details of the subject! 1J. Barrande, Syst. Silur. Bohéme, vol. v., 1879. Hall and Clarke, Introd. Palaeozoic. Brach. (Palaeont. of New York, 1892-1894). Davidson, Monogr. 49g! 492 FOSSIL BRACHIOPODA CHAP. Since all Brachiopods are inhabitants of the sea, the geologist at once recognises as a marine deposit any bed which contains their remains. Under favourable conditions they swarmed in the seas of Palaeozoic and Mesozoic times. Beds of limestone are fre- quently almost entirely composed of their shells, as, for instance, some of the Devonian limestones of Bohemia. Often they give the facies to the fauna and outnumber in species and individuals all the other organisms of the period. The Ungulite Sandstone (Cambrian) of Russia and the Productus Limestone of the Salt Range in India of Carboniferous and Permian age are well- known examples. Many species seem to have been gregarious in habit; thus Productus giganteus of the Carboniferous Limestone may gen- erally be found in crowded masses, as in some localities in Yorkshire. The fact that certain species of Brachiopods characterise definite stratigraphical horizons or “zones” gives them occasion- ally an importance equal to that of Graptolites; for instance, the Ecardinate species Trematis corona marks a set of beds in the Ordovician, and the isolated Stringocephalus Burtini is restricted to the upper part of the Middle Devonian, giving to the lime- stone on that horizon its distinctive name. It is noteworthy also how certain species affect a sandy and others a calcareous sea- bottom, so that beds of the same age show differences in their Brachiopod fauna owing to a dissimilar lithological composition. While few of the recent Brachiopods reach a large size, some of the extinct species measure several inches in breadth, but the great Productus giganteus attained the width of even a foot. The bright colours of the shells of the living animals are not generally preserved amongst the fossil species from the older rocks; yet in a Carboniferous TYerebratula we can even now detect the purple bands in some specimens, and a Cretaceous Rhynchonella similarly exhibits its original colour. The Brachiopoda are evidently a group in its decline, as the geological record shows; but they date back from the earliest known fossiliferous rocks, in which the Ecardinate division is alone represented. As we ascend through the stratigraphical series the number and variety of genera and species belonging to Brit. Foss. Brach. (Palaeont. Soc., 1851-1884). Waagen, Salt Range Fossils (Mem. Geol. Surv. India, 1879-1885). XVIII ECARDINES: EXTERNAL CHARACTERS 493 both divisions rapidly increase until in the united Ordovician and Silurian there are nearly 2000 species and about 70 genera. From this point of maximum development down to the present day there is a gradual decrease in numbers. According to Davidson, at least 17 Upper Tertiary species are still living on our sea-bottoms; and many recent Mediterra- nean forms occur in the Pliocene rocks of the islands and shores of that sea, and in the Crags of East Anglia. A brief review of the chief characteristics of fossil Brachio- poda is given below. Those genera which have the greatest zoological or geological importance can alone be noticed owing to the exigencies of space. I. ECARDINES External Characters A considerable diversity of external form is met with even in this division, from the hmpet-like Discina to the flattened tongue- shaped Lingula. ‘The valves have most commonly a smooth ex- ternal surface with delicate growth-lines; but sometimes pittings (Trematis) or radiating ribs (Crania) are present, and in a few forms the shell is furnished with spines (Stphonotreta), which perhaps serve to anchor it in the soft mud of the sea-bottom. The usual mode of fixation was by means of the pedicle (= pe- duncle or stalk), which either (1) passed out simply between the posterior gaping portion of the valves (Lingula), or (2) lay in a slit in the ventral valve (Lingulella), or (8) pierced the sub- stance of the latter valve by a definite foramen (Discina). The first-mentioned condition of the pedicle seems the most primitive. Rarely the pedicle was absent, and the shell was attached by the whole surface of the ventral valve (Crania, p. 467). The two valves in the fossil Ecardines were held together by muscular action, though in some families ( Zrimerellidae) we see traces of articulating processes. The “hinge line,” or line along which the valves worked as on a hinge, is in most forms more or less curved. A “hinge area” (7.e. that portion of the shell gen- erally smoother than other parts of the valves, more or less tri- angular in form, and lying between the beaks on one or both sides of the hinge line), is usually absent in the Ecardines. 494 FOSSIL BRACHIOPODA CHAP. Internal Characters Owing to the rarity of well-preserved interiors of valves in this division, our knowledge of their internal characters is still far from satisfactory. The arrangement of the muscular impres- sions varies greatly amongst extinct genera, but we are often able to interpret them with a considerable amount of certainty by a study of the scars and the muscles of the well-known recent LTingula (Fig. 322). The extreme specialisation of the muscles in many of the earliest genera (e.g. Lingula) is remarkable, and points to a long but so far undiscovered ancestry in pre-Cambrian times. In fossil species of Crania and Lingula the muscle-scars correspond closely with those in the living representatives of these genera. In the most highly specialised family of the Ecardines—the Trimerel- lidae—we meet with features of peculiar interest.2. The muscle-scars in this family (Fig. 323, A, B) are most remarkable for the develop- ment of the so-called ‘“cres- cent,” (q.7.s.) which skirts Fig. 322. — Muscle-scars of Lingula anatina. the posterior margin of both Inner surface of A, Pedicle-valve or ven- valves aS a sub-cardinal im- tral valve. B, Brachial or dorsal valve; ig ek . ° p.s, parietal scar; uw, umbonal muscle; f, (Uses Ul It is believed to transmedians; c,centrals; a.m.e, laterals be the trace of a strong post- (a, anteriors; m, middles; e, externals). parietal muscular wall, anal- ogous in position to that of Zingula. The three pairs of “lat- eral” muscle-scars in the latter genus seem to be represented by the “terminal” (s) and “lateral” (7) scars on the crescent 1 The results of the investigations of King (Ann. Mag. Nat. Hist., 4th ser., vol. xii., 1873) and of Brooks (Chesapeake Zool. Laboratory, Scientific 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 Zrimerellidae. A pair of “transverse” scars (¢) occurs in each valve between the “terminals” and the antero-lateral edge of the “platform” (7). “Cardinal” (v), “sub-cardinal” (w), and “umbo-lateral” (2) 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; j, platform; &, platform vaults; /, median plate; m, median scars; n, anterior scars; 0, lateral scars; p, post-median scars ; q, 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 sears. B, Brachial or dorsal valve: e, cardinal sockets; j, platform; k, platform vaults; 7, median plate; m, median scars; 7, anterior scars; g, crown crescent ; r, 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. 323, 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 liver. 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 Obolidae 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, hes 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 Lingulidae 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 Ecardines. A transversely cr 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 (Proboscidella). 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 versdé; 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, 825). 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. 826), or tripartite, or even quadripartite ; but in Rhynchonella and some other genera it is rudimentary. VOL, Ill 2K 498 FOSSIL BRACHIOPODA CHAP. A “hinge area” (Fig. 334, ¢.a) 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 aie’, mes Fic. 325.—Conchidium galea- tum. Transverse section. d, Dorsal valve; d.s, dorsal septum; s, socket plate; v, 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) sears; 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 he 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. 828). In some cases this foramen becomes closed in old age. The dorsal valve in a few cases has its beak perforated by a a f P .. eel wee Fic. 327.— Rhynchonella ad Boueti. .(Cornbrash.) Fic. 328. — Terebratula sella. d, Deltidium; f, fora- (Lower Greensand.) d, Del- men. tidium; /, 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 hes 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 generaasa low ridge or strongly developed partition (Wald- 500 FOSSIL BRACHIOPODA CHAP. heimia, Fig. 829, ss; and Stringocephalus, Fig. 826, 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; ¢, teeth. B, Interior of dorsal valve: a.a, anterior adductor (occlusor) scars; a.p, posterior adductor (occlusor) scars; ¢.p, cardinal process; er, crura; d.s, dental sockets; Ap, 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. 834), 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. 333, 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 Sor 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. 826, 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 Thecidiidae 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 GSpirifera, Fig. 330), or towards the interior of the dorsal valve (Atrypa, Fig. 332), or towards each other (Glasszia); 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 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 Tes- ticardines are illustrated by Productus giganteus (Fig. 383), Leptaena rhomboidalis (Fig. 334), and Waldheimia jlavescens (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- Fic. 330.—Spirifera striata. (Carboniferous 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 6 CK ~ Fic. 331.— Atrypa reticu- Fig. 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. fl i 7H | Ih j por fall A Si ANY | NN ae h i" AO Bae \ *) f u f mn i (7, biehis ’ {iH i {IN \ \ IH ith I \) th) uy fs i , | 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 sears; i, ‘‘ reni- form impressions’’; ca, cardinal process; h, hinge line; p, brachial prominence; 8, 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 he the two occlusor scars (a). In the dorsal valve anterior and posterior pairs of occlusor scars (a.a, ap) are visible. The minute structure of the calcareous shell of the Testi- cardines is of flattened fibrous prisms inclined at a very acute Fia. 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-.d, posterior oc- clusor scars; C.d, hinge area; ¢.p, car- dinal process; d, chilidium ; s, dental sockets; v.s, vascu- lar sinuses. NINN 4 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. Rance. — 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. PRINCIPAL GENERA. — Discina, Orbiculoidea, Trematis. Family. Craniidae 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). RanGE. — 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. Concayo-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. 534.) Rance. — 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. 352), 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. RANGE. — Devonian to Recent; maximum development in Mesozoic times. PrincrpaAL 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. RanGeE. — 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. Caleareous 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, Linyulella, and Obolella are characteristic. XVIII STRATIGRAPHICAL DISTRIBUTION 507 In the Ordovician many new genera of the Testicardines make their appearance, such as Strophomena, Leptaena, Atrypa, LRhynchonella, 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. With the commencement of Devonian times many species and genera become extinct, but new forms come in ( Terebratula, 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 individuals 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 Moninckina 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 GSpori- 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 ECARDINES Lingulidae Obolidae Discinidae Craniidae Trimerellidae Lingula. . Lingulella . Obolus . Obolella Kutorgina . Linnarssonia . Trematis Siphonotreta . Acrotreta . Discina . Crania . Trimerella. Dinobolus . TESTICARDINES Productidae Strophomenidae Koninckinidae Spiriferidae Atrypidae Rhynchonellidae Terebratulidae Argiopidae Stringocephalidae Thecidiidae Productus . Chonetes Strophalosia Orthis Skenidium . Clitambonites Strophomena . Stropheodonta Leptaena Orthothetes Davidsonia Koninckina Koninckella Spirifera Spiriferina . Cyr: ei 4 Syringothyris . Uncites . : Athyris. Merista . Retzia . Atrypa . Dayia Coelospira . Rhynchonella Stenochisma . Stricklandia Conchidium Terebratula Terebratulina Waldheimia Terebratella Kingena Magas . . Centronella Argiope . Cistella . Stringocephalus Thecidium . Oldhamina ; | Carboniferous | Permian | Jurassic Recent | Ordovician | Devonian | Silurian | | Cretaceous | | Tertiary | | Trias | | | | | | Cambrian XVIII 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 Discinisea. 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 XVIII PHYLOGENY AND ONTOGENY Bt 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 lies in a slit or sinus ( Trematidae), 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 Atre- mata (type i.); the Meotremata (type i.); the Protremata (type ii.); 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 is the most primitive form of all, we may place it at the root of the phylogenetic tree. From it sprang 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 Conchidium 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. XVIII 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 spire-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) ABRALTIA, 391 Absorption of internal portions of shell, 259 Abyssal Mollusca, 574 Acanthinula, 441 Acanthoceras, 399 Acanthochiton, 403, 403 Acanthodoris, 434 Acanthopleura, 408 ; eyes, 188 Acavus, 805, 304, 335, 441 Acera, 245, 430 Achatina, 278, ; 328- 337, 333, 442, 448 ; jaw, 211; food, 39 ; size of egg, 124; AN 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, 356, 414 Acrotreta, 504, 508 Actaeon, 250, 427, 428, 429; radula, 217, 250 ; streptoneurous, 203 n. Actaeonella, 430 Actaeonia, 432 Actaeonina, 250, 429 Actinoceras, 394 Actinodonta, 447 Acusta, 305, 316, 318, 441 Adacna, 12, 297, 455 Adalaria, 434 Adamsiella, 414 Addisonia, 412 Adelphoceras, 395 Adeorbis, 416 Admete, 426 Aegires, 434 Aegista, 305, 316, 441 Aegoceras, 398 VOL. I | Aeolis, 10, 152, 482; radula, 217, 229; stinging cells, 65; mimicked by Sagartia, 68; warning colora- tion, 72 Aerope, 328, 383, 440; habits, 54 Aestivation, 25 Aetheria, 328-336, 452 ; variation, 92 Africarion, 335, 440 Agaronia, 426 Age of snails, 39 Aglossa, 7 Agnatha, habits, 51 Akiodoris, 434 Alaba, 415 Alaria, 418 radula, 215; : Alariopsis, 420 Albersia, 320 Albino varieties, 87 Alcadia, 348-551, 410 Alderia, 432 Alexia, 439 Alicia, 459 Allognathus, 441 Allopagus, 452 Alloposidae, 384 Alvania, 415 Alycaeus, 266, 302 f., Amalia, 440 Amalthea, 78 Amaltheus, 398 Amastra, 443 Amaura, 411 Amberleya, 409 Ambonychia, 449 Amicula, 404 Ammonites, 247, 393, 398, 398; sutures, 396 ; aptychus, 397 Ammonoidea, 396 f. Amnicola, 325, 415 Amoria, radula, 222 3 21 309, 319, 414 514 Ampelita, 535, 442 Amphibola, 10, 18, 439; breathing, 161; radula, 236 Amphibulimus, 352, 442 ; Amphidoxa, 358 Amphidromus, 301, 305, 317, 310, 559, 442; radula, 2383 Amphineura, 8, 400; breathing organs, 154, 168 ; nervous system, 208 ; geni- talia, 145 Amphipeplea, 439 Amphiperas, 419 Amphisphyra, 430 Amphissa, 423 Amphitretus, 383 Ampullaria, 17, 416; self-burial, 42; spawn, 125; breathing organs, 151, 158 ; jaws, 212; shell, 249, 263; oper- culuin, 268; distribution, 294, 320, 322, 343, 359 Ampullarina, 302, 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, 293, 296 Ancilla, 267, 426 Ancillina, 426 Ancistrochirus, 391 Ancistromesus, 405 Ancistrotenthis, 391 Ancula, 484; radula, 229, 230; warn- ing coloration, 72 Anculotus, 417 Ancyloceras, 247, 399 Ancylus, 19, 439; breathing, hibernating, 27; radula, 235 Aneitea, 325, 443 Angitrema, 540, 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, £48 Anoplophora, 451 Anostoma, 248, 266, 356, 3858, 442; aperture, 63 Anthracosia, 451 radula, 233 162 ; MOLLUSCA — BRACHIOPODA Anura, 424 Anus, 209, 241 Apera, 334, 440 Aperostoma, 544, 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, 216 Apricardia, 455 Aptychus, 397 Aptyxiella, 417 Aptyxis, 424 Aral Sea, Zimnaea from near, 84; Cardium from, 91 Arca, 14, 171, 278, 448; eyes, 191 Arcacea, 448 Arcachon, oyster-parks at, 105 Arcestes, 397 Archidoris, 434, 434; protective colora- tion, 78 Architeuthis, 578, 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, 440; shell, 175, 245, 246 ; hardier than Helix, 24; voracity, 50 f.; egg- laying, 42 f.; protective coloration, 70; pulmonary orifice, 160; food, 179; smell, 193 f.; radula, 233; dis- tribution, 285 Arionta, 341, 353, 441 Ariophanta, 31, 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, 143 Asolene, 416 Aspergillum, 262, 459 Aspidelus, 329, 440 INDEX Aspidoceras, 399 Assiminea, 415 Astarte, 451 Asthenothaerus, 459 Astralium, 409 Athoracophorus, 4435 — see Janella Athyris, 499, 500, 505 ; stratigraphical distribution, 507, 508 Atilia, 423 Atlanta, 421, 422; foot, 200 Atopocochlis, 350, 441 Atremata, 511 Atretia, distribution, 486, 487 Atrypa, 501, 502, 505; stratigraphical distribution, 507, 508 Atrypidae, 501, 505, 508 Aturia, 393, 395 Atys, 428, 430 Aucapitaine, H., on tenacity of life, 58 Aucella, 449 Aulopoma, 157, 304, 474; operculum, 269 Aulosteges, 504; stratigraphical distri- bution, 507 Auricula, 439, 439 Auriculella, 327, 443 Auriculidae, 17, 18, 260, 4389, 439; lung, 160; eyes, 186; radula, 255 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, 390 515 Batissa, 320, 452 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, 580 Belopteridae, 388 Belosepia, 386, 388 Beloteuthis, 390 Bembizx, 376, 408 Benedictia, 290, 415 Benthobia, 577 Benthodolium, Berendtia, 441 Beudant, experiments on Mollusca, 12 Bideford Bridge and mussels, 117 Binney, Dr., on epiphragm, 28 Onn oli | 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, 259 Borsonia, 426 Borus, 356-358, 441 Bourcieria, 357, 410 Bourquetia, 417 Bourguignatia, 332 Bouvier — see Fischer Boysia, 802, 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 MOLLUSCA — BRACHIOPODA Brachytrema, 417 Brackish-water species, 14 Branchiae, 151, 155, 164 Branchial siphon, 155, 164, 175 Braun, on self-impregnation, 44 Breathing organs— see Respiration, Branchiae Brechites, 459 Breeding, periodicity in, 129 Broderipia, 408 Brotia, 305 Brownia, 138 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, 301, 339, 442; protective habits, 70 ; B. pallidior, 38 Bulimulus, 278, 334, 339-359, 442; jaw, 211, 233; radula, 233; varia- tion, 87 Bulimus, 278, 542-359, 355, 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, 4] Busycon, 424; egg-capsules, 125— see Fulgur Butterell, Mr., on habits of Testacella, 52 Byssocardium, 455 Byssus gland, 201 CADLINA, 434 Cadoceras, 393 Cadulus, 376, 445 Caecilianella, 442; habitat, 48 ; eyes, 186 Calcarella, 138 California, land Mollusca, 280 Calliostoma, 408 ; jaws, 212 Callistochiton, 403 Callochiton, 403 Callogaza, 408 Callonia, 442 Callopoma, 409 Calma, protective coloration, 74 Calybium, 410 Calycia, 320, 442 Calycidoris, 434 Calyptraea, 248, 412 Camaena, 305, 306, 315, 316, 441 Cambrian, Mollusca of the, 2 Camitia, 409 Bal | money made from, 97; | | 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, 347-351, 441 Carbonicola, 451 Cardiacea, 454 Cardiapoda, 421 Cardilia, 454 Cardinal plate, 500 Cardinal process, 497, 501 Cardinalia, 408 Cardinia, 451 Cardita, 273, 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 Caspia, 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, 804, 474 Caterpillars mimicking Clausilia, 68 Cathaica, 316, 441 Catinella, 443 Cavolinia, 158, 436; eyes, 186 Cecina, 414 Cenia, 432; breathing, 152 Centrodoris, 434; radula, 230 Centronella, 499, 506, 508 Cephalopoda, 378 f.; defined, 5; ink, 65; egg-laying, 127; embryo, 183; branchiae, 168; osphradium, 195; foot, 200; nervous system, 206 ; jaws, 218; radula, 236 Cepolis, 349-351, 441 Cerastoma, 423 Cerastus, 331, 441 Cerata of Nudibranchs, 71, 159 INDEX Ceratites, 397, 398 ; 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, 203; 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 | suture, 396 Charopa, 319, 323-327, 441 Chascax, 424 Chelinodura, 430 Chelotropis, 135 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, 158, 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, 819-3824, 447 Chlorostoma, 408 Chlorostracia, 807 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 Smo done, 4843 jaws, 212; radula, 230 Chrysallida, 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, 485 ; 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, Ait Clathurella, 426 Clausilia, 442, 442; mimicked by cater- pillars, 68; monstrosity, 251; dis- tribution, 285 f., 294, 305-318, 382, 399-396 ; 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, 486, 436 Cleopatra, 294, 328, 331, 336, 416 Clessin, on duration of life, 39 Clessinia, 12, 297 Clio, 486, 436 Cliona, enemy of oysters, 112 Clione, 158, 438 Clionopsis, 437 Clitambonites, 498, 505; stratigraph- ical distribution, 507, 508, 511 Clithon, 827, 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, 358, 442 Coelospira, 505, 508 Cold winter, effect on oysters, 112 ; on mussels, 116 Collinge, W. E., on prowen and burial of shells, 4] OCollisella, 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, 328, 330, 443 Cominella, 16, 424 Composition of shell, 252 Concha, 465 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, 314, 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, 305 Corona, 27, 442 Coronaria, 297 Coryda, 346-551, 441 Coryphella, 432 Cosmoceras, 399 Cowry used as money, 96 Coyote trapped by Haliotis, 57 Oranchia, 391 Crania, 464, 467, 468, 469, 471, 472, 473, 475, 476, 477, 487; distribu- tion, 485 ; fossil, 493, 494, 504 ; strati- eraphical 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 Crenipecten, 450 : Crepidula, 248, 257, 412, 412; para- Sitic, 78 Crepipatella, 248, 412 Creseis, 486, 436; eyes, 186 Crimora, 434; radula, 229 Crioceras, 247, 399, 399 Cristigibba, 311, 319, 320, 441 Crossostoma, 408 | Crucibulum, 248, 412 OCryptochiton, 245, 371, 402, 404 Cryptochorda, 425 Cryptoconchus, 404 Cryptophthalmus, 430 Cryptostracon, 353, 441 Ctenidia, 151 — see Branchiae Ctenopoma, 346-351, 414 Cucullaea, 274, £448 Cultellus, 457 Cuma, 423 Cumingia, 453 Cuspidaria, 459; branchiae, 168 Cuvierina, 4386, 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, 306-319, 829-334, 344, 352-358, 414 ; jaws, 212; radula, 21 Cyclostoma, 528, 331-388, 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, 537, 414 Cyclotopsis, 338, 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, 453 ; distribution, 285, 294 Cyrenella, 453 INDEX 519 Cyrtia, 505; stratigraphical distribu- | Diloma, 408 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 Dawidsonia, 505, 508 Dawsonella, 410 Dayia, 505, 508 Decapoda, 384 f. Decollation, 260 Deep-sea Mollusca, 374 De Folin, experiment on Cyclostoma, 157 Deianira, 410 Delage, experiments on otocysts, 197 Delphinula, 409 Deltidium, 499 Dendronotus, 433; protective colora- tion, 72; habits, 51 Dentalium, 6, 444, 445 ; used as money, 97 ; veliger, 181; raduia, 228 Dimorphoptychia, 410 Dimya, 450 Dinobolus, 504, 508 Dinoplax, 403 Ditocardia, 9, 170, 405 f. Diplodonta, 452 Diplommatina, 302-827, 413 Diplomphalus, 522, 323, 440 Diplopoma, 346, 351, 414 Dipsaccus, 424 Dipsas, 807 Discina, 464, 468, 471, 475, 487; distri- bution, 485; fossil, 495, 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, 451 Dolium, 419; acid secretion, 237 Donaz, 269, 446, 453 Dondersia, 404 Dorcasia, 3335, 441 Doridium, 430 Doridunculus, 434; radula, 229 Doriopsis, 434 | Doris, breathing organs, 159; radula, Dentellaria, 350-355, 441 ; aperture, 63 | Desert species, 25, 85 Deshayesia, 411 Desmoulea, 423 Development of fertilised ovum. 150 f. Dexiobranchaea, 437 Diadema, 414 Diala, 415 Dialeuca, 441 Diaphora, 314 Diaphorostoma, 412 Diastema, 418 Diastoma, 417 Diaulula, 434 Dibaphus, 425 Dibranchiata, 380; eye, 183; nervous system, 207 Diceras, 269, 455 Didaena, 12; 291, 755 Differences of sex, 133 Dignomia, 511 Digonopora, 154, 144 230 Dorsanum, 423 Dosidicus, 390 Dosinia, 454 Doto, 433; protective coloration, 71 Dreissensia, 14, 128, 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, 804, 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, 38 Egg-laying of Arion, 42 f.; of Mollusca generally, 123 Eglisia, 411 Eider-duck, shells used by, 102 520 Elaea, 322, 440 Elasmoneura, 411 Eledone, 385, 385; radula, 236 Elizia, 456 Elysia, 432 ; protective coloration, 73 ; breathing, 152 ; radula, 217, 2380, 432 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; Z£. bicolor, 279 Enoplochiton, 408, 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 Ergaea, 248, 412 Erinna, 327, 439 Erosion, 276 Ervilia, 454 Erycina, 453 Escargotiéres, 119 Estria, 829, 440 Estuarine species, 14 Ethalia, 409 Eucalodium, 260, 353, 442 Euchelus, 408 Euchrysallis, 420 Eudioptus, 442 Eudoxochiton, 403 Euhadra, 316, 318, 447 Eulamellibranchiata, 451; gill, 166, 167 Eulima, 422; parasitic, 77, 79 Eulimella, 250, 422 Eulota, 296, 441 Euomphalus, 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, 347-351, 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, 3828, 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, 302, 415 Fossarus, 413 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, 447 Fruticocampylaea, 296 Fryeria, 434 | Fulgur, 249, 424 | Fusispira, 420 Fusus, 262, 424 GADINTIA, 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, 130 _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, 408 Gibbus, 328-338, 440, 440 Gillia, 415 Gills — see Branchiae Girasia, 301, 3804, 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, 3538, 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, 437 521 Gyroceras, 247, 395 Gyrotoma, 417 HADRA, 306, 315, 319-825, 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, 488, 438 Haminea, 428, 430; protective colora- tion, 73 Hamites, 399 Hamulina, 399 Hanleyia, 403 Hapatlus, 331, 442 Harpa, radula, 425, 216, 221; self- mutilation, 45 Harpagodes, 418 Harpoceras, 399 Harvella, 454 Hatching of eggs, 43 Hazay, on duration of life, 39; on variation in Limnaea, 93 Hearing powers of Mollusca, 196 Heart, in classification, 9 ; action during hibernation, 26 ; and branchiae, 169 Hectocotylus arm, 157 f. Helcion, 405 ; protective coloration, 69 Helcioniscus, 405 Hele, F. M., on Hyalinia, 33; on Stenogyra, 34 Helicarion, 309, 316, 325, 3382, 440; radula, 232; habits, 45, 67 Helicidae, radula, 232, 234 Helicina, 305, 306, 316-827, 388-858, 410; origin, 21; exterminated by cold, 24 Helicophanta, 335, 386, 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, 840 ; cicatricosa, 316 ; creni- labris, 45 ; delphinuloides, 297 ; deser- torum, 37, 38, 70, 294; jidelis, 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, 522 38, 180; niciensis, 292; nux denticu- lata, 350; palliata, 340; pisana, 25; habits, 33 ; pomatia, 25, 34, 40; eye, 181; pomum, 322; pulchella, 279; richmondiana, 322; rosacea, 259; rostrata, 347; rota, 314; rufescens, pulsations, 26; similaris, 279; sou- verbiana, 336, 441; strigata, 293; tristis, habits, 49; turricula, 297; Veatchii, 38; Waltoni, 304; Wollas- toni, 297 ; zonata, 298 Helix aspersa, homing, 35; smell, 36 ; duration of life, 39; growth, 40; strength, 45 ; boring rock, 50; varia- tion, 87, 89; eaten, 119; hybrid union, 130 ; generative organs, 140 f., 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 Hemiitoma, 265 Hemitrichia, 314 Hemitrochus, 346-351, 441 Hemphillia, 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, 432; protective coloration, 73 Hermaphrodite Mollusca, 184, 140, 145 Hermit-crabs, shells used by, 102 Hero, 432 Heterocardia, 454 Heterodiceras, 455 Heteropoda, 9, 420 f.; radula, 228; 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 Hinnites, 257, 450 Hipponyx, 248, 412 Hippopus, 455 Hippurites, 455, 456 Histiopsis, 391 Histioteuthis, 391 Holcostoma, 417 MOLLUSCA — BRACHIOPODA Holohepatica, 433 Holopella, 411 Holospira, 339, 355, 442 Holostomata, 156 Homalogyra, 413; radula, 223 Homalonyx, 245, 3438-358, 443 Homing powers of Mollusca, 34 Homorus, 3380-837, 443 Hoplites, 399 Hoplopteron, 422 Horea, 332 Horiostoma, 409 Hot springs, Mollusca living in, 25 Huronia, 394 Hyalaea, 10, 436 Hyalimax, 245, 305, 306, 3388, 443 Hyaline stylet, 240 Hyalinia, 440; pulsations, 26; food, 33; smell, 194; dart, 143; radula, 232, 234; distribution, 287 f., 318, 340-357 ; 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, 382, 415; H. ulvae, egg-laying, 128 Hydrocena, 298, 410; radula, 226 Hymenoptera build in dead shells, 102 Hypobranchaea, 434; radula, 230 Hypotrema, 448 Hypselostoma, 248, 302, 305, 514, 442 Hyria, 344, 452 Hystricella, 297 IANTHINA, 360, 126, 411; egg-cap- sules, 125; eyes, 186; radula, 224 LIapetella, 385 Iberus, 285-293, 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, 889 Ink-sac, 241 Inoceramus, 449 Insects eaten by Mollusca, 82 Insularia, 319, 320 Intestine, 241 Io, 16, 340, 417 Topas, 423 Iphigenia, 16, 453 Travadia, 305, 415 Tridina, 294 TIrus, 297 INDEX 523 Jsanda, 409 Ischnochiton, 403 Tsidora, 298, 320-827, 333, 356, 359, 439 Ismenia, 404 Tsocardia, 269, 451, 451 TIsodonta, 453 Isomeria, 345, 356, 441 Issa, 434 JAMAICIA, 414 Janella, 161, 443; pulmonary orifice, 161 Janellidae, radula, 284; distribution, 321-326 Janus, 432 Japonia, 318 Jaws, 210 Jeanerettia, 346-851, 441 Jeffreys, Dr., on Limnaea, Neptunea, 193 Jeffreysia, 415; radula, 223 Jorunna, protective coloration, 75 Jouannettia, 457 Jullienia, 307, 415 Jumala, 424 KALIELLA, 301, 304, 810, 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, 352 Lagena, 424 Lagochilus, 309, 316-519, 414 Lamellaria, 245, 411; 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, 528, 331, 416 Lankester, Prof. E. Ray, on shell- gland, 132 ; 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 34; on | | Leila, 344, 452 | Leonia, 414 Leia, 348-551, 442 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 Leucotaenta, 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, 351, 442 Lima, 178, 179, 450; habits, 63 Limacidae, radula, 232 Limacina, 59, 249, 486, 436 Limapontia, 429, 432; breathing, 152 Limax, 245, 440; food, 31, 179 ; varia- tion, 86; pulmonary orifice, 160; shell, 175 ; jaw, 211 ; radula, 217 ; distribu- 524 tion, 285, 324; L. agrestis, eats May flies, 31; arborum, slime, 50; food, 31; flavus, food, 33, 36; habits, 35, 36 ; gagates, 279, 358 ; maximus, 32, 161 ; eats raw beef, 32 ; cannibalism, 32; sexual union, 128; smell, 195 f. Limea, 450 Limicolaria, 329-332, 443 Limnaea, 439; self-impregnation, 44 ; development and variation, 84, 92, 95; size affected by volume of water, 94; eggs, 124; sexual union, 154; jaw, 211; radula, 217,235; L. awricularia, 24; glutinosa, sudden appearance, 46; Hookeri, 25 ; involuta, 82, 278, 287 ; peregra, 10,180; burial, 27; food, 54, 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, 455 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, 475, 475, 477, 478, 487; habits, 483, 484 ; distribution, 485; fossil, 493, 494, 503; stratigraphical distribution, 506, 508, 510, 511 Lingulelia, 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; MOLLUSCA — BRACHIOPODA operculum, 269 ; erosion, 276; L. lit- torea, in America, 374 ; obtusata, gen- erative organs, 185; rudis, 150; Prof. Herdman’s experiments on, 151 n. Littorinida, 415 Lituites, 247, 395 Liver, 239 ; liver-fluke, 61 Livinhacea, 333, 359, 441 Livona, 408 ; radula, 226 ; operculum, 268 Lloyd, W. A., on Nassa, 198 Lobiger, 432 Lobites, 397 Loligo, 578-389 ; glands, 186 ; modified arm, 139; eye, 188; radula, 236; club, 381; L. punctata, egg-laying, 127 ; vulgaris, larva, 153 Loligopsis, 391 Loliguneula, 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, 348-351, 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, 348-353, 442 Macroceras, 440 Macrochilus, 417 Macrochlamys, 296, 299, 301 f., 510, 316-322, 440 Macrocyclis, 558, 359, £442 Macron, 424 Macroon, 441 Macroscaphites, 247, 399, 399 Macroschisma, 265, 406 Mactra, 271, 446, 454 Macularia, 285, 291, 292 f., 441 Magas, 506; stratigraphical distribu- tion, 507, 508 eee ee 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, 3388, 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, 457 Megalomastoma, 544, 414 Megalomphalus, 416 Megaspira, 358, 442 Megatebennus, 406 Megerlia, distribution, 486, 487 Meladomus, 249, 328, 331, 416 Melampus, 18, 199, 250, 489, 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, 285, 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, 434 525 Microcystis, 825, 524, 327, 338, 440 Microgaza, 408 Micromelania, 12, 297 Microphysa, protective habits, 70 Microplax, 403 Micropyrgus, 415 Microvoluta, 425 Middendorfiia, 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, 456 Monodonta, 408, 408 ; tentaculae, 178 Monogonopora, 154, 140 Monomerella, 496, 504 Monopleura, 456 Monotis, 449 Monotocardia, 9, 170, 417 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, 300 f., 835, 440 ; radula, 217, 232 Napaeus, 296-299, 316, 442 Naranio, 454 Narica, 412 Nassa, 428; egg-capsules, 126 ; sense of smell, 198 Nassodonta, 423 Nassopsis, 352 Natica, 246, 263, 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, 327, 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, 133, 216, 228, 404, 404 ; breathing organs, 154; nervous sys- tem, 203 Neothauma, 332 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, 470; radula, 226 Neritina, 256, 410; origin, 16, 17, 21; egg-laying, 128; eye, 181; distribu- tion, 285, 291 f., 324, 827; N. fluvia- tilis, habitat, 12, 25 Neritoma, 410 Neritopsis, 409; radula, 226; opercu- lum, 269 Nervous system, 201 f. Nestotis, 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, 805 Nucula, 254, 269, 2738, 447 Nuculidae, otocyst, 197 ; foot, 201 Nuculina, 448 Nudibranchiata, 432; defined, 10 ; pro- tective and warning colours, 71 f.; breathing organs, 159 Nummutlina, 295 Nuttallina, 403 OBBA, 3811, 315, 441 Obbina, 806, 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, 159, 140 Octopus, 879-386 ; egg-capsules, 127; vision, 184; radula, 236 ; crop, 238 Ocythoe, 384; hectocotylus, 138 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, 163 ; eyes, 187 Onchidoris, radula, 250 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, 203 ; radula, 229 Opisthoporus, 266, 300, 514-316, 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, 342-358, 355, 442; habits, 27 ; variation, 87; jaw, 211; radula, 233, 234 Orthis, 505; stratigraphical distribu- tion, 506, 507, 511 Orthoceras, 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, 135 Ovoviviparous genera, 123 Ovula, 419; protective coloration, 70, 75 ; radula, 80, 224; used as money, 97 Ovum, development of fertilised, 150 Oxychona, 358 I94 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, 329-335, 441, 442 Pachybathron, 425 Pachychilus, 354 Pachydesma_ crassatelloides, made from, 97 Pachydomidae, 451 Pachydrobia, 807, 415 Pachylabra, 416 Pachyotus, 354, 386, 355, 358, 447 Pachypoma, 409 Pachystyla, 3387, 440 Pachytypus, 451 Padollus, 407 Palaearctic region, 284 f. Palaeoneilo, 447 Palaeosolen, 457 Palaina, 327, 413 Palio, 434 Pallial line and sinus, 270 Pallifera, 540, 440 Palliobranchiata, 464 Paludina, 416; penis, 136; eye, 181, vision, 184; P. vivipara, 24—see also Vivipara Paludomus, 332, 336, 3888, 417 Panama, Mollusca of, 3 Panda, 322, 325, 385 money | Pandora, 458 Papuans, use of shells, 99 Papuina, 809, 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, 440 Parmella, 326, 440 Parmophorus, 406 Parthena, 349-352, 350, 441 Parts of univalve shell, 262; bivalve, 269 Partula, 519-527, 326, 442; radula, 2383 Paryphanta, 321, 825, 440 Paryphostoma, 416 Passamaiella, 332 Patella, 405, 464; as food, 56 f.; eye, 182; radula, 214, 215, 227; crop, 288; anus, 241; kidneys, 242; shell, 262 ; P. vulgata, veliger, 132; breathing organs, etc., 156, 157 528 MOLLUSCA — BRACHIOPODA Patelliform shell in various genera, 19 Paterina, 509, 510, 511 Patinella, radula, 227 Patula, 297, 298, 318-358, 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, 355 Pellicula, 352, 442 Peltoceras, 399 Pentadactylus, 423 Peraclis, 436 Pereiraea, 418 Perideris, 328-330, 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, 355, 440 Petersia, 420 Petraeus, 295, 831, 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; coloration, 73; radula, 229, 230 Philomycus, 245, 318, 440 Philonexis, 188 protective | Philopotamis, 304, 417 Phoenicobius, 315, 441 Pholadacea, 457 Pholadidea, 457 | Pholadomya, 459 Pholas, 245, 274, 447, 457; in fresh water, 15 Phos, 424 Photinula, 408 Phragmophora, 386 Phyllidia, 434; 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, 23, 27 Pileolus, 410 | 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 Placobranchus, 432 Placostylus, 322, 323-825, 359, 442; radula, 233 Placuna, 448; P. placenta used for windows, 101 Placunanomia, £48 Placunopsis, 448 Plagioptycha, 847-851, 441 Plagioptychus, 456 Planaxis, 417 Planispira, 311, 812, 319, 441 Planorbis, 27, 247, 439; monstrosity, 93 ; eye, 181; P. albus, distribution, 282 Platyceras, 76, 412 Platydoris, 434 Platypoda, 471 Platyschisma, 413 Plaxiphora, 403 Plecochilus, 442 Plecotrema, 439 Plectambonites, 505 _ Plectomya, 459 | Plectopylis, 303, 805, 314, 316; aper- ture, 63 INDEX Plectostylus, 358, 442 Plectotropis, 305, 806, 310, 311, 314— 318, 441 Plectrophorus, 298 Plesiastarte, 451 Plesiotriton, 420 Pleurobranchaea, 431; jaws, 212 Pleurobranchoidea, 431 Pleurobranchus, 245, 428, 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, 357 Pleurotoma, 426, 426; slit, 2638, 265 Pleurotomaria, 266, 373, 376, 407, 407; | | Protobranchiata, 447; branchiae, 166 _ Protoma, 417 | Protremata, 511 Pliny the elder, on use of snails, 118,120 | prices given for recent, 122; slit, 156; radula, 226 Plicatula, 450 Plocamopherus, 434 Plochelaea, 425 Plutonia, 298, 440 Pneumoderma, 158, 437, 438 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, 447 ; aperture, 63 Polygyratia, 246, 263, 357, 442 Polymita, 346- 351, 347, 44d Polyplacophora, 9, 407 f.; radula, 228 Polytremaria, 266, 407 Pomatia, 285, 293, 295, 441 Pomatias, 288, 289, 292 f., 302, 413 Pomatiopsis, Gis Pomaulaz, 409 Pompholyx, 250, 341, 439 Ponsonbya, 332 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 WANT TYT 431; warning | _ Prophysaon, 341, 441; 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 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 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, 328 Pseudosubulina, 440 Ptenoglossa, 224, 411 Pterinaea, 449 Pteroceras, 256, 262, 418 Pteroctopus, 384 Pterocyclus, 266, 267, 300, 516, 414; tube, 157 Pterodonta, 418 Pteropoda, 7, 434; breathing organs, 158 ; foot, 200; radula, 280 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; operctlum, 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, 329-335, 441, 442 Radiolites, 456 Radius, 419 Radsia, 403 Radula, 215 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 Rathouisia, 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, 123, 134 f. Requienia, 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 Rhiostoma, 247, 266, 3809, 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 Rhysota, 67, 3810, 314, 316, 319, 440 Rhytida, 319-826, 333, 359, £40 ; habits, 54; radula, 232 Rillya, 442 Rimella, 418 Rimula, 265, 406 Ringicula, 430; radula, 230 Risella, 413 Rissoa, 415 Rissoina, 415 Robillardia, 77 Rochebrunia, 331, 414 Rock-boring snails, 49 Rolleia, 549 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, 31; on protective coloration in slugs, 70 Schasicheila, 347, 351, 354, 410 radula, INDEX 531 Schismope, 266, 407 Schizochiton, 187, 402, 403 Schizodus, 448 Schizoglossa, 325, 440 Schizoplax, 403 Schizostoma, 413 Schloenbacia, 398 Scintilla, 175, 453 Scissurella, 265, 407; radula, 226 Sclerochiton, 403 Scrobicularia, 15, 164, 453; siphons, 164 Sculptaria, 333 Scurria, 405 Scutalus, 356, 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, 389 Sepiella, 389 _ Sepiola, 389; glands, 136 ; radula, 236 Sepioloidea, 389 Sepiophora, 388 Sepioteuthis, 390; hectocotylus, 139 Septaria, 337, 3388, 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; shape of bivalve, 445 Shell-gland, primitive, 132 Shells as money, 96 f. ; as ornament, etc., 98 f.; various uses of, 98 f.; prices given for rare, 121 ; sinistral, 249 Shores of N. Asia, no littoral fauna, 2 Showers of shells, 47 Sigaretus, 186, 245, 267, 477; foot, 198 Sight, 180 Silenia, 459; branchiae, 168 | 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 Helix, 45 Singular habitat, 48 Sinistral shells, 249 Sinistralia, 424 Sinusigera, 138 Sipho, 424 Siphonalia, 424 Siphonaria, 18, 431; classification, 19 ; breathing organs, 151, 152 Siphonarioidea, 437 Siphonodentalium, 444 Siphonostomata, 156 Siphonotreta, 493, 496, 504; strati- graphical distribution, 507, 508 Siphons, 178; in burrowing genera, 165 ; branchial, 155 Sistrum, 75, 423; radula of S. spec- trum, 79, 222 Sitala, 301, 304, 310, 314-819, 333, 440 Skirgard, 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, 336, 452 Spekia, 333 Spermatophore, in Cephalopoda, 137 ; in Helix, 142 vision, 190; 532 Spermatozoa, forms of, 136 Sphaerium, 453 Sphenia, 456 Sphenodiscus, 398 Sphyradium, £442 Spines, use of, 64 Spiraculum, 266, 414 Sptraxis, 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, 387, 388 Spirulirostra, 380, 586, 388 Spondylium, 500 Spondylus, 257, 446, 450, 450; ocelli, 191; genital orifice, 242 Spongiobranchaea, 437 Spongiochiton, 403 Sportella, 453 Starfish eat oysters, 110 distribu- 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, 54 ; smell, 194 ; Goodallii, 279 ; octona, sudden appearance, 47 Stenogyridae, radula, 254 Stenopus, 440; habits, 45 Stenothyra, 415 Stenotis, £16 Stenotrema, 340, 441 Stephanoceras, 399 Stepsanoda, 358 Stilifer, 76, 77, 79, 422 Stiliferina, 76, 422 Stiliger, 432 Stilina, 76 Stoastoma, 348-851, 410 Stoloteuthis, 389 Stomach, 239 Stomatella, 408 Stonatia, 408 Stomatodon, 302, 417 Strebelia, 353, 440 Strength of Helix, 45 Strephobasis, 417 Strepsidura, 424 Streptaulus, 414 Streptaxis, 302, 306, 309, 314-331, 3438, 357-359, 440 ; variation, 87 Streptoneura, 203, 404 Streptosiphon, 424 Streptostele, 329, 338, 440 Streptostyla, 343-355, 353, 440 Stricklandia, 505 ; stratigraphical dis- tribution, 507, 508 | | MOLLUSCA — BRACHIOPODA Strigatella, 425 Stringocephalidae, 506, 508 Stringocephalus, 492, 497, 498, 500, 501, 506; stratigraphical distribu- tion, 507, 508 Strobila, 340, 345-3538 Strobilops, 442 | Strombidae, habits, 64; penis, 186 Strombina, 423 Strombus, 69, 200, 252, 478; 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, 345-355, 442; S. nana, 278 Strophochilus, 358, 441 Strophomena, 499, 505; stratigraphical distribution, 507, 508 Strophomenidae, 500, 505, 508 | Strophostoma, 248, 41h | 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, 325, 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, 2387 Surcula, 426 Sycotypus, 424 Synaptocochlea, 408 Syndosmya, 453 Syringothyris, 500, 508 Syrnola, 422 Syrnolopis, 332, 383 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 INDEX Tectarius, 413 Tectibranchiata, 10, 429 Tectura, 805, 405 Tectus, 408 Teeth in aperture of the shell, 63 Teinostoma, 247, 408 Teinotis, 407 Telescopium, 252, 416 Tellina, 446, 458, 453; 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 ; jumping powers, 64 Terebra, 246, 265, 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 T. balthica, 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, 397 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), 522, 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, 333, 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, 828-327, 388, 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, 419 Trematis, 492, 493, 504; stratigraphi- cal distribution, 507, 508 Trematonotus, 407 Tremoctopus, 384; radula, 286; hec- tocotylus, 187 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, 484 534 MOLLUSCA — BRACHIOPODA Triopha, 434 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, 806, 521, 324, 327, 333, 441 ; Trochonanina, 331, 440 Trochosphere, 5, 130 Trochotoma, 266, 407 Trochus, 265, 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, 332, 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, 423 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 Limazx, 128 Unionidae, origin of, 15; eaten by rats, 57; larvae, 146 Urocyclus, 381, 440 Urosalpinz, 423 Utriculus, 430 Uvanilla, 409 VAGINULA, 245, 319, 348, 352, 443 Vaginulidae, radula, 234; anus, 241 Valletia, 456 Vallonia, 441 Valwvata, 1383, 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, 151 Velutina, 275, 411; radula, 223 Veneracea, 454 Venericardia, 451 Venerupis, 454 Veniella, 451 Venilicardia, 451 Venus, 270, 271, 446, 454; V. merce- naria, 97, 3874 Verania, 391 Vermetus, 247, 418; radula, 228 Veronicella, 443 Verticordia, 458 Vertigo, 827, 442; V. arctica, 287 Vexilla, 423 Vibex, 417 Vitrella, 289 Vitrina, 22, 296 f., 382, 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, 343, 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 olutolithes, 425 Volutolyria, 425; radula, 222 Volutomitra, 425; radula, 221 Volutopsis, 423 Volvaria, 429 Volvatella, 430 Volwula, 430 Vulsella, 75, 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 Dale, XENOPHORA, 412; habits, 64 Xenopoma, 346, 351 Xerophila, 285, 296, 441 Xesta, 310, 319, 821, 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. ITI, MACMILLAN & CO.’S PUBLICATIONS ON NATURAL HISTORY, 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.BA.LFrour, 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. Svo. $6.50. BEDDARD (Ff. E.).— Animal Colouration. With 4 Coloured Plates, and Woodcuts in the Text. By FRANK EvEeRS 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. 800 pp. 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.—HElementary Text-Book of Zodlogy. By Dr. C. Craus. 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.- EIMER.— Organic Evolution as the Result of the Inheritance of Ac- quired Characters, according to the Laws of Organic Growth. By Dr. G. H. THEODOR EIMER, Professor of Zodlogy 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. WaArRDE). —Tales of the Birds. With Illustrations. New and cheaper Edition. $1.25. A Year with the Birds. With Illustrations. $1.25. GUNTHER (ALBERT 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 HERTWIG. Translated from the Third German Edition by EDWARD 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. J the Press. HUXLEY and MARTIN.—A Course of Elementary Instruction in Practical Biology. By T. H. Huxtey, 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.).—Blementary 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 Zod- logical Institute in Jena. Translated into English by HENRY M. BERNARD., 2 BOOKS “ON NATORAL HISTORY, ETC. M.A. (Cantab.) and MATILDA BERNARD. Part I. Complete with Index and 383 Illustrations. S8vo. $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 Blementary Anatomy. By St. GEorRGE MIvarrt, F.R.S., Lecturer in Comparative Anatomy at St. Mary’s Hospital. With up- wards of 400 Illustrations. 16mo. $1.75. PARKER. — A Course of Instruction in Zodtomy (Vertebrata). By T. JEFFERY PARKER. With seventy-four Illustrations. 1I2mo. $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.” — New 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. WEISMANN.—Essays upon Heredity and Kindred Biological Prob- lems. By Dr. AuGusT WEISMANN, Professor in the University of Freiburg in Breisgau. Edited by EDwarp B. Pou.ton, 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 series were published in October; the third will be ready in April, and the fourth in October, 1895. . From the Greeks to Darwin. Buckram. 8vo. . 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 Sczence (London). *“ If 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 (A mphioxus 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 Amphioxus 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 aoe ee by the Greek mind to the full development wrought out by Darwin.” — Milwaukee entined. MACMILLAN & CO., PUBLISHERS, 66 FIFTH AVENUE, - - 2 - - NEW YORK. 2 org — < ¢ ‘ Af ey : _ af 4 “| : q a - i ead f f , ; iy os tt : cm i 7 / 7 7 + -” i Y i 1 4 i > 1 i - ¥ 1 jl : - i \ : y Ff Y ‘ ' : io & rs ; a) : y = - g ; i ¢ ‘ 4 a) r = i : t » . 7 : J i ' y i 1 $ 3 F ' ; _ : Z F I ts % : i ; “4 7 * 7 ' Lares t i a : — a oF j ’ v 7 i : > ‘ ; ea ~~ of U F 7 se i a“ ‘ 4 We) ef OP oh » eT. 4 r . - ‘ « : 7 Bs ; ? ‘ 8.98/84 : £/9.6.0;4,0.6.4 016% 2 a eeiec® ee ee shew rt a7 oe oe oe oe oe Oe pe ee tes 1 a ei hee + ae ae ed oh taht te tahoe o,8-3 a6 a4 Sie