Shell, when full grown and mature, is solid, oval, convex, very smooth, involute; the spire entirely posterior, very small, often concealed by a calcareous layer deposited by the lobes of the mantle, leaving in some species a small cavity like an umbilicus; aperture longitudinal, very narrow, slightly curved, as long as the shell, with edges internally dentated, and notched at each extremity. Shell, when young and immature, is very thin, the edges of the aperture not dentated; the right margin sharp and not reflected. Cypræa cerina. C. exanthema. C. tigris. C. tigrina. C. Argus. C. testudinaria. C. Mauritiana. C. mappa. C. Arabica. C. histrio. C. scurra. C. rattus. C. stercoraria. C. mus. C. ventriculus. C. Aurora. C. lynx. C. adusta. C. erosa. C. caurica. C. Isabella. C. ocellata. C. cribraria. C. turdus. C. olivacea. C. stolida. C. hirundo. C. undata. C. zigzag. C. flaveola. C. sanguinolenta. C. poraria. C. ursellus. C. asellus. C. moniliaris. C. stercus-muscarum. C. talpa. C. carneola. C. lurida. C. vitellus. C. caput-serpentis. C. cinerea. C. zonata. C. sordida. C. icterina. C. miliaris. C. variolaria. C. rufa. C. cicercula. C. lota. C. globulus. C. ovulata. C. helvola. C. Arabicula. C. staphylæa. C. pustulata. C. nucleus. C. limacina. C. moneta. C. obvelata. C. annulus. C. radians. C. oniscus. C.