GASTROPODS. 



383 



The fig-shells ^Pirula) have an extensive foot, like Dolium, but the mantle is 

 largely lobed on each side, and reflexed upon the shell. This is of an elongate pear- 

 shape, with a short spire and a long canal, and has the surface transversely 

 striated or ridged, or more or less cancellated. There are nine recent species 

 belonging to this genus, which is also found fossil in the Chalk and Tertiary 

 deposits. The genus is included in the Doliidce. 



fig-shell (Pirula ventricosa), from above and beneath (nat. size). 



The cowry, or, more properly, kauri shells (Cyprceidce), are so well known 

 that a description is scarcely necessary. They are all formed much after the 

 same pattern, and are almost always coated with a brilliant enamel, caused by the 

 lateral lobes of the mantle being reflexed upon the shell. In the young the shells 

 exhibit a short spire, which in the course of growth becomes entirely or almost 

 concealed. Many of the shells are exceedingly beautiful, and some of the animals 

 are even more brilliantly coloured. The cowries have no operculum, but a large 

 foot, and can retract their bodies entirely within the shell, notwithstanding the 

 narrowness of the aperture. The shells, as is well known, are sold as ornaments, 

 and some of the rarer kinds are greatly prized by collectors. A small yellow 

 species, the money-cowry (Cyprcea moneta), abundant in some parts of the Indian 

 and Pacific Oceans, is used as coin in India and among the negroes of certain 

 parts of Africa. The orange cowry (C. aurora), one of the finest of the group, 

 used to be worn by the chiefs in the Friendly Islands. The cowries, of which 

 nearly two hundred species are known, are found most abundantly in tropical 

 regions, but a few stragglers occur in temperate seas. Only one small and ridged 

 species (C. europcea) is found on the British coasts, and about a hundred fossil 

 forms, chiefly Tertiary, are known. The genus Ovula is allied to Cyprasa as 



