268 CASSIDID^E. 



FAMILY CASSIDID^. 



Shell solid, sttbglobular or triangular, with short spire ; whorls 

 sometimes varicose ; aperture terminating anteriorly in a short, 

 recurved canal ; columella callous, spread out, usually plicate ; 

 outer lip-margin thickened, dentate within. 



Operculum corneous, concentric, elongated, semilunar, the 

 nucleus at the centre of the inner margin (PL 1, fig. 43). 



Animal with large head, eyes at the exterior base of the ten- 

 tacles, proboscis cylindrical, extensible, mantle and foot large. 

 Dentition (PL 1, fig. 44\ The Cassides are active and voracious, 

 living in sandy localities and preying on bivalve mollusks. The 

 varices of the shell persist in its interior. 



Synopsis of Genera. 

 Genus CASSIS (Klein, 1753), Lamarck, 1799. 



Shell usually rather solid and thick, with the last whorl very 

 large, often varicose ; aperture longitudinal, narrow ; outer lip 

 with a thickened, reflected margin, and dentate within ; inner lip 

 rugosely plicate. On the use of species of Cass'S in cameo cut- 

 ting, see Structural and Systematic Conchology, ii, 200. About 

 twenty-five species are known, inhabiting warm seas. The genus 

 first appeared in the tertiary. 



Section 1. CASSIS (sensu stricto = Goniogalea, Morch, 1857). 



Spire short, mouth narrow, dentate, lip externally margined, 

 columella plicate. C. Madagascar iensis, Lam. 



Section II. LEVENIA, Gray, 1847. 



Shell oval, subcylindrical, spire short, conic ; aperture narrow, 

 contracted in the middle, columellar lip plicate throughout, outer 

 lip without external rib, dentate, inflected above. C. coarctata, 

 Gray. 



Section III. CYPR^CASSIS, Stutchbnry, 1837. 



Shell ovate, spire short ; mouth narrow, subcanaliculate behind, 

 columella plicate its entire length ; varices none or obsolete. ? No 

 operculum. C. rufa, Linn. 



Subgenus SEMICASSTS (Klein, 1753), Morch, 1852. 

 Spire moderate, sharp ; shell oval with revolving sulci ; lip 



