GASTEROPODA. 



79 



notched below, or having a short canal bent back ; the 

 outer lip with a recurved thickening. — Marine. 



Cassis. Lam. — Shell large, heavy, sometimes with 

 varices, spire short ; aperture either long 

 and narrow, or rather oval, terminated by 

 a short canal abruptly curved towards the 

 back of the shell; outer lip generally 

 toothed, and thickened ; the columella 

 often wrinkled, toothed, or grained, and 

 generally widely expanded ; operculum 

 horny and crescent-shaped. Animal, head cassis tuierosa. 

 large, prolonged into a short snout; two 

 tentacula, with eyes on a thickening at the external base ; 

 foot large, but thin and flat ; the mantle forms a veil-like 

 appendage over the head, and is also prolonged into a 

 breathing tube very much turned back. — 33 species*; 

 also fossil. 



These animals sometimes grow to a very large size, 

 requiring of course a corresponding magnitude of shell. 

 They are chiefly brought from the Indian seas, but a few 

 species are found in the Mediterranean ; they live on the 

 sand, at some distance from the shore, and occasionally 

 burrow so as entirely to hide themselves. In some 

 species the columellar lip projects above the spire, giving 

 a flat appearance to the lower part of the shell. 



The shells of the Cassis rufa and other species are 

 exquisitely sculptured by Italian artists in imitation of 

 antique cameos, the different strata of colouring matter 

 resembling those of the onyx and other precious stones. 

 Of these a great variety of ornaments are made, and of 

 late years a considerable trade has been carried on in 



* Reeve's Iconica. 



