104 POPULAR CONCHOLOGY. 



Ihese shells are only found in the fossil state, 

 and are very irregular in form, and by most na- 

 turalists are now included in the next genus. 



64. Chama. — Shell irregular, spiny, or 

 rough, inequivalve; bosses recurved and un- 



equal, turning either to the right or left ; one 

 thick and long tooth in one valve, and a deep 

 pit in the other ; ligament external. Animal: 

 foot small. — 17 species recent, and 13 fossil. 



These shells appear to present almost every 

 variety of shape and colour; the former 

 fact is perhaps owing to the accidents of their 

 position. They are confined to warm climates, 

 the Mediterranean being the lowest tempera- 

 ture. They are found usually at small depths 

 in the sea, affixed by the largest valve to rocks, 

 &c, and occasionally united together in large 



