330 



Gasteropoda. - 



-lIOLLUSCA.- 



-Proeoscidifera, 



The young are large when born, not leaving their 

 mother till they are an inch in length. Four or five 

 are found in each animal. Adanson in his voyage to 

 Senegal, informs ns that one .species of these shells, the 

 " Yets " as they are called ( Yctus Neptuni), are thrown 

 up by the high winds of April, in such quantities as 

 sometimes to cover the shore, and that the animals, 

 which often weigh five or sis pounds, are smoked and 

 preserved by the natives of Senegal against times of 

 famine, to which they are frequently exposed. The 

 nucleus or apex of the Yets is very large, callous, and 

 irregular ; it is often thrown off entire. The sjiecies 

 of Yettts are chiefly natives of Africa. The remainder 

 of the Volutes are oviparous, the young being arranged 

 in the oviduct of the female in a long stiing without 

 egg shells. 



Genus Cvmbium. — The genus Cymbium has a ven- 

 tricose shell with a short, depressed spire, which is 

 frequently crowned with a diadem of strong spines. 

 Tlie aperture is very large and expanded, and the 

 nucleus or apex of the shell is regularly spiral and 

 persistent. Tlie foot is not so large as in the Yets, 

 and the mantle is inclosed. The surface of the shell 

 is covered with a smooth, greenish-brown epidernii.s, 

 and the shell itself usually ornamented with a variety 

 of colours. Some of the species are very large, and 

 they are almost all natives of New Holland, and the 

 great islands of the Eastern Archipelago. One or two 

 of the larger, such as Cymbium athiopicum and dia- 

 dema, are used by the natives of these seas as vessels 

 for baling the water out of their canoes. 



Genus Scapiia. — A number of species of Volutes, 

 instead of being ventricose, are fusiform or ovate in 

 shape, and covered with a thin, smooth epidermis. The 

 last whirl is often spinose or tubercled, and the nucleus 

 is smooth or crenulated. As the shells increase in size 

 tliC animals till the nuclei of the spire with solid 

 calcareous matter. These belong to the genus Scapha. 

 They are tolerably numerous, and are principally found 

 natives of the East Indian islands, though some are 

 found also in Australia. Some of the shells are very 

 beautiful, very elegant in form, and the rarer amongst 

 them, as Scajiha Junonia, for example, fetch very high 

 prices. The same may be said of Scapha mamilla, 



Fig. 216. 



Scapha vespertiUo and auimaJ. 



from Van Dieraen's Land, remarkable for the large 

 nucleus of the spire, and the size of the shell. Specimens 

 scarcely exist in any other collection than that of the 

 British Museum, which is peculiarly rich in this family. 

 Fig. 210 represents the S. vespertiUo and animal. 



Genus Voluta. — The name Voluta, as a generic 

 appellation, is now restricted to a small number of 

 species. The shells are of a dense structure, of an 

 ovate shape, and the pillar or columella has four or five 

 strongly-developed oblique plaits or folds in front, and 

 several smaller transverse ones behind. The surface 

 of the shell is generally ornamented with transverse 

 interrupted bands and striiie, so disposed as to resemble 

 a bar of music. 



THE VOLUTA MUSICA or MusiC SHELL, from the 

 West Indies, has obtained its name from this circum- 

 stance ; and the peculiar appearance of notes of music 

 is equally v/ell exhibited in the Voluta hcbraa. This 

 is the only genus of the family in which we find an 

 operculum. It is horny, annular, and distinct. 



Genus Volutella. — In the several genera we have 

 briefly noticed the mantle of the animal is inclosed 

 within the shell. But a considerable number of species 

 are remarkable for having the lobes of the nianlle 

 produced, and partially covering the shell. These 

 constitute the genus Volutella. In one of the most 

 remarkable of the species, the Volutella amjulata, 

 these lobes are largely expanded, and overspread the 

 spire entirely, which is generally much produced, and 

 covered with a smooth, glassy deposit. In others, 

 these lobes are more moderately expanded, and only 

 cover the lower side of the spire, leaving a callous band 

 on the suture of the upper side. Such are the fine 

 large, and rather ponderous V. imperialis, with its spire 

 crowned with a circle of strong spines ; the beautiful 

 and elegant little V. Cyndilola, &c. 



THE DATE SHELLS, Porcellanina (genus Margi- 

 ndla of Lamarck), are remarkable for the brilliancy 

 and variety of their markings. The mantle lobes 

 are expanded and spread over the shell, which is 

 covered with a highly-polished coat laid over the epi- 

 dermis. The animals are said by some to reiemhlo 

 those of the Cowries {Cyp>ra:a), but they have the 

 retractile proboscis, the lingual membrane, and dis- 

 position of the teeth of the Volutideg. The form of 

 the shell also, with its conic spire, its plaited columella, 

 and its thickened outer lip, marks its relation with this 

 family. The species are numerous, upwards of ninety 

 having been described. They prevail more especially 

 along the shores of Africa, but are found also in the 

 West Indies, Brazil, India, China, and Austialia. They 

 are quicker and more lively in their movements than 

 the Cowries, crawling pretty briskly, and moving their 

 tentacles in diflerent directions. The foot of the animal 

 appears to be double-edged in fiont, and this part is 

 said by Mr. A. Adams, who has had opportunities of 

 seeing some of the species in their native localities, to 

 be endowed with acute sensation, the animal making 

 ufe of these two portions of the body as feelers. Their 

 favourite locality is shallow water on clear sands ; and 

 when seen in full activity, they are said to be objects 

 of singular interest and beauty. 



Family— CASSIDID^. 



The family of HELMET SHELLS {Cassididm) have 

 the foot largely dilated ; and the operculum, which it 

 bears near its posterior extremitj', is annular, ovate, or 



