83 



interior of the shell extends in ample folds about the aperture^ and secretes 

 that rich display of enamel which affords so beautiful a material for the 

 engraving of Cameos. The C. tuberosa from the West Indies, is the species 

 commonly used for this purpose from its delicate purity of colour ; the well- 

 know Bull's Mouth, Cassis rufa, is a famihar example of the great power 

 which this genus exhibits in the formation of shell, but the enamel is not 

 so suitable for gem -engraving on account of its deep blood-red colour. 



M. Deshayes informs us, from his observations of the Cassis sulcosa on 

 the shores of the Mediterranean, that it is very probable the animal hves 

 upon the juices of different Bivalve Mollusks, whose shells it pierces with 

 its probosis after the manner of the Miirices, being found dwelling in the 

 sand, and just in those places where Bivalves abound ; he describes the 

 Cassis, however, as not possessing much activity. The operculum, which 

 is rarely obtained with the shell, is horny and of a peculiar crescent shape, 

 crenidated at the edge and rayed with deep striae. 



The Cassides are not very numerous, they inhabit chiefly the Mauritius, 

 Ceylon, the Philippines and West Indies; two species are found in the 

 Mediterranean, but none on our own coast. 



Species. 



Figures. 



Cassis glauca. PI. D. Shell with animal, showing the thin flattened disk 

 with its crescent-shaped radiated operculum, head and tentacles with 

 sessile eyes, proboscis partially withdrawn, and prominently developed 

 respiratory siphon proceeding from a fold in the front edge of the 

 mantle, and passing tlirough the recurved ascending canal of the shell. — 

 From the 'Voyage de V Astrolabe! 



Cassis areola. PI. 6. Pig. 28. Shell, showing the aperture, varices, and 

 wrinkled structure of the outer and columellar lips. 



m2 



