CONCHIFERA OR BIVALVES. 123 



angular pit for the ligament. — Animal, foot 

 cylindrical. — 6 species recent, and 18 fossil. 



The Lima is almost always white ; some of 

 the species are rare. It is found on the coasts 

 of America and the Isle of France. It has a 

 brown horny epidermis. 



The genus Plagiostoma of Lamarck, which 

 he placed after Lima, and which contained six 

 species, is by Deshayes divided between Lima 

 and Spondylus. He thinks the genus unne- 

 cessary. 



79. Pecten. — Shell regular, nearly round, 

 eared, ribbed or furrowed, 

 inequivalve ; ligament in- 

 ternal and triangular ; 

 hinge margin straight ; no 

 teeth; bosses contiguous. 

 — Animal, foot small, di- 

 lated at the extremity. — 

 61 species recent*, and 

 58 entirely fossil. 



The animal of the Pecten has the power of 

 making frequent and sudden contractions of its 



* Several of the recent species are also found fossil. 



