5o 



ZOOLOGICAL 



ORDEK PROSOBRANCHIATA 



COISIDJE (Cones). Plate 27, Map v. 



The ConidiB are an extensive group of marine molluscs, at least 1500 

 species having been described. They are of universal distribution, and are 

 a favourite group with collectors, owing to the number of handsome species 

 contained therein. The typical genus, Conus, comprises over 500 species, the 

 great majority of which are found in eastern seas. A single species occurs in 

 the Mediterranean. The genus Pleurotoma and its allies have a wider dis- 

 tribution, ranging into temperate and arctic seas. They are sometimes 

 regarded as a separate family (Pleurotomidse). About a dozen species of 

 Pleurotoma and half that number of Mangilia are recorded from British 

 waters, but the more typical Conus is absent. 



OLIVID^G (Olives). Plate 27, Map v. 



The Olividse, of which about 150 species have been described, are 

 molluscs with beautiful shells of a more or less cylindrical shape and a 

 highly-polished surface. They are chiefly natives of tropical seas, but a 

 few species have been recorded from cooler regions, such as Japan and 

 Patagonia. They are not known from British waters. The principal 

 genera are Olivet, with about 60 species, and Ancilla, with about 45. 



VOLUTIN (Volutes). Plate 27, Map v. 



Over 100 species are referred to this family, which contains many 

 handsome and, to collectors, valuable molluscs. They have a world-wide 

 distribution, but some of the genera have a restricted range. Thus Pro- 

 vocator is confined to the island of Kerguelen, Wyvillea to the Marion and 

 Crozet Islands, and Volutolyria to the Antilles. Volutomitra is purely 

 arctic and antarctic, while the typical genus Valuta occurs in all the 

 warmer seas, and is especially well represented in those of Australia. 



BUCCINID.E (Whelks, &c). Plate 27, Map v. 



Over 300 species, and numerous genera, of this family have been 

 described, which are found in all seas. The tyj)ical genus Buccinum, how- 

 ever, has a purely northern distribution, with over 20 species. Two of 

 these occur in British waters, and the better-known (B. undatum) is 

 brought to London and other markets in large quantities, forming a 

 favourite food in many parts of the country. In the antarctic region 

 this genus appears to be represented by Neobuccinum, which occurs at 

 Kerguelen. The genus Cominella contains 20 species, occurring at the 

 Cape of Good Hope, also in New Zealand and Australian seas. 



MURIOID^l (Murex, &c). Plate 27, Map vi. 



This family is of world-wide distribution, and contains about 500 species, 

 many of which possess extremely handsome shells. The typical genus, 

 Murex, contains about 300 species whose shells are furnished with 

 numerous rows of variously shaped spines or tubercles. These molluscs 

 occur chiefly in tropical and subtropical seas. Another important genus, 

 Trophon, on the other hand, is typically arctic and antarctic, containing 

 about 40 species. Purpura is an important genus, widely distributed, and 

 sometimes placed with its allies in a distinct sub-family. About a score of 

 species of Muricidse inhabit British waters. 



CASSIDID.E (Helmet-Shells). Plate 27, Map vi. 



The molluscs of this family possess large, handsome shells which are 

 extensively used by the cameo-cutter, owing to the fact that they are made 

 up of differently coloured layers. They are mostly inhabitants of warm 

 seas, but three species occur in the Mediterranean and one off the Atlantic 

 coast of France, while one has been dredged from deep water off the south- 

 west of Ireland. The tenants of these fine shells are active, carnivorous 

 molluscs, whose food is principally bivalved members of the same great 

 class. 



CYPR^ID-E (Cowries). Plate 27, Map vi. 

 This family comprises about 300 species of molluscs, which are mainly 

 inhabitants of tropical and subtropical seas. Three species, however, are 

 on the British list, and a few others occur in the Mediterranean and off 

 the European coasts. The typical genus {Cyprsea) contains about half the 

 species, whose shells are remarkable for their high polish. One of the best- 

 known forms is the Money-Cowry (Cyprsea moneta), so extensively used for 

 currency in India and Africa. Ovula is another important genus, contain- 

 ing about 75 species. 



STROMBID.E (Wing-Shells). Plate 28, Map i. 



About 90 species of this family have been described, some of which are 

 ■of very large size and curiously shaped. They owe their popular name to 

 the wing-like expansion of the outer lip found in some species. The typical 

 genus Strombus contains about 70 species, which are widely distributed in 

 warm seas. The so-called "fountain-shell " of the West Indies (S. gigas) is 

 a beautiful pink species whose shell is ground to powder and used in the 

 manufacture of fine porcelain, while it is also cut into cameos. Aporrhais 

 pespelecani, the " pelican's-foot shell," is a common species round our coasts, 

 and one of two which alone represent the family in British waters. 



MELANIIM (Melania, &c). Plate 28, Map i. 



The Melaniidse are a group of over 500 species of fresh-water molluscs 

 with a wide distribution in the Old World and a much more restricted range 

 in America. The typical genus Melania contains about 400 species, which 

 are widely distributed, but mainly tropical. Paludomus is restricted to 

 India, Ceylon, and Sumatra, with 25 species ; while Typhobia is a remark- 

 able form confined to Lake Tanganyika, in Central Africa. 



HYDROBIID.E (Hydrobia, &c). Plate 28, Map i. 



The members of this interesting family are extremely widely distribut d 

 the various species inhabiting fresh and brackish waters in almost all n t' 

 of the world. Five species are regarded as British, viz., three belonoi no - % 

 the typical genus Hydrobia and two to Bithinia. The distribution of s & 

 of the exotic genera is of much interest. Thus Baicalia is confined t 

 Lake Baikal; Tanganyika to Lake Tanganyika; Jullienia to Cambodi 

 Potamopyrgus to New Zealand ; Littorinida to South America ; Amnio, 1 ' 

 and Fluminicola to North America. By some authors the Hydrobiidsp 

 regarded as merely a sub-family of the Rissoidse, which are marine • f 

 this sole reason, however, it is perhaps advisable to keep them apart 



PALUDINID^ (Viviparous Pond-Snails). Plate 28, Map i. 



The members of this family are mainly found in the fresh waters f 

 the Northern Hemisphere, but a few species are found in the tron' 

 and in southern regions. Over 100 species have been described th 

 majority of which belong to the typical genus (Paludina). Of this ^enus 

 two species are found widely distributed in Britain, the better-known be' 

 Paludina vivipara, called in popular parlance the viviparous Pond-Sn '1 

 The genus Lioplax contains a few species which are confined to North 

 America. The family appears to be absent from New Zealand and 

 Polynesia. 



VALVATHXE (Valvata, &c). Plate 28, Map ii. 



The Valvatidse are small fresh-water molluscs occurring for the most 

 part in Europe and North America. Only a single genus {Valvata) is 

 recognised, but, like most of the genera of Mollusca, this has been sub- 

 divided into a number of sub-genera. Curiously enough, the section 

 Lyogyrus is represented in New Caledonia, far away from all other members 

 of the family. Two species of Valvata (V. piscinalis and V. cristata) are 

 universally distributed in Britain. 



AMPULLARIID^E (Ampullaria, &c). Plate 28, Map ii. 



The molluscs of this family are amphibious, and live in ponds and 

 marshes principally within the tropics. They are somewhat larger than the 

 Pond-Snails of the previous families, and are known among dealers as 

 "apple shells." About 200 species have been described, most of which 

 belong to the genus Ampullaria. In the New World these molluscs ran»e 

 as far north as Mexico and Georgia. Asolene, sometimes regarded as a 

 separate genus, is confined to South America ; while Lanistes belongs 

 solely to Africa and Madagascar. 



CYCLOPHORID^l (Cyclophorus, &c). Plate 28, Map ii. 



This is an extensive family, containing about 800 species and numerous 

 genera, which are widely distributed in both hemispheres. They are 

 terrestrial molluscs, and at one time were regarded as members of the great 

 group Pulmonata. The presence of an operculum closing the mouth of the 

 shell is, however, a character which marks them off' clearly from the true 

 land-snails and slugs. The most important genera are : Pomatias, found in 

 Southern Europe and North Africa; Diplommatina, of the Oriental and 

 Australian Regions; Cyclophorus, with 200 tropical species widely dis- 

 tributed ; and Aperostoma, confined to Central and South America. 



CYCLOSTOMATIDiE (Cyclostoma, &c). Plate 28, Map ii. 



Like the Cyclophoridrc the members of the present family are terrestrial, 

 and their shells are provided with an operculum. About 250 species have 

 been described, half of which belong to the typical genus Cyclostoma. A 

 single species (Cyclostoma elegans) occurs in Britain, where it is found 

 under stones, &c, in many parts of the country. Choanopoma, with 55 

 species, is restricted to the West Indies; while Cistula, with 42, is found 

 both in the latter islands and in Central America. Omphalotropis has 25 

 species, occurring in Mauritius, the Philippine Islands, and Polynesia; 

 and lastly, the two genera, Ilainesia and Acroptychia, are peculiar to 

 Madagascar. 



ACICULID.E (Acicula). Plate 28, Map iii. 



This is a limited group of operculated land molluscs, containing a single 

 genus (Acicula) and about a score of species, which are confined to Europe, 

 Asia Minor, and North Africa. One species (Acicula lineata) is found in 

 Britain, occurring over a wide area and met with under stones or among 

 decayed leaves in wooded districts. The present family is sometimes 

 united with the Cyclostomatida?. 



PROSERPINiaE (Proserpina). Plate 28, Map iii. 



This family of molluscs is, like the three previous ones, terrestrial, but 

 the shells have no operculum. A single genus (Proserpina) is known, 

 divided into a few sub-genera. The distribution of the few species is 

 limited, for they are confined to the Neotropical region, and occur only in 

 Cuba, Jamaica, and a few limited areas in Central, and the northern portion 

 of South America. 



HELICINIDJE (Helicina, &c). Plate 28, Map iii. 

 The molluscs of this family are, in general appearance, like the well- 

 known snails of the genus Helix, but differ from them in the possession of 

 an operculum. They are an extensive group, comprising over 600 species, 

 which are found in the tropical and subtropical portions of America, Japan, 

 South-eastern Asia, and the Australian Region. Stoastoma is a genus con- 

 taining 82 species, of which 80 are found only in Jamaica. 



