CASSIDID^. 199 



OvuLUM, Brug. 



Syn. — Amphiperas, Gronov. Simnia, Risso. 



Distr — 75 sp. Tropical and subtropical. Fossil. Tertiary — . 

 0. pyrifo7-mis, Sowb. (Ixi, 12, 13). 



Shell veutricose, convolute, attenuated and subacuminated at 

 both ends ; outer lip of adult thickened and inflected. 



These shells are not ornamented with the rich and varied 

 colors of the cowries, having but little pattern-painting; they are 

 at once distinguished from them by the attenuated and frequently 

 produced ends. 



Simnia was proposed for a few species, with sharp aperture- 

 margin, which have proved to be the young of typical Ovulse. 



CALPURNUS, Montf. ( Cypraella, Swains.) Cypraeiform, gibbous, 

 with a small tubercle at each extremity. 0. verrucosum^ Linn. 

 (Ixi, 14, 15). 



CYPHOMA, Bolten. i Carinea, Swains.) Shell with a transverse 

 dorsal rib ; inner lip smooth, outer lip very slightly crenulated. 

 G. gibbosum, Linn. (Ixi, 16, 17). 



VOLVA, Bolten. (Birostra, Swains. Radius, Montf.) Shell 

 ventricose in the middle, both extremities prolonged into canals ; 

 lips both without teeth. Animal, mantle-margin with glandular 

 tubercles, foot narrow, folded lengthwise on itself, adapted for 

 creeping on the narrow, rounded branches of gorgonise and corals 

 — on which it is supposed to feed. G. volva, Linn. (Ixi, 18). 



CRiTHE, Gould, Shell ovate with produced extremities, and a 

 delicate groove at the summit ; aperture narrow, outer lip 

 unarmed ; base of the shell with about eight coarse laminae, 

 passing into the aperture, and having the appearance of denta- 

 tions on the inner lip. 0. afomaria, Gld. China Seas. 



Pedicularia, Swainson. 



Syn. — Thyreus, Phil. 



Distr. — 9 recent sp. Europe, Polynesia. 1 Miocene sp. Eur. 

 P. Sicula^ Swains. (Ixi, 19, 20). 



Shell small, limpet-like, irregular, with small, short spire, con- 

 cealed with the growth, and a radiately ribbed surface when 

 young; mouth large, lips simple, irregular. Animal with eyes 

 sessile at the outer bases of the tentacles, mantle enclosed, not 

 produced into a siphon in front, foot small. Operculum none. 



DENTiORA, Pease. Columella plane or excavated, compressed 

 and dentate within. D. rubida, Pease. Sandwich Is. 



Family CASSIDIDJE. 



Shell solid, subglobular or triangular; spire short, whorls 

 sometimes varicose ; aperture terminating anteriorly in a shortly 

 recurved canal, columella callous, usually plicated, outer lip 

 ribbed, dentate within. 



