CONCHIFERA OR BIVALVES. 93 



by a byssus to rocks. They are brought from 

 Amboyna, New Holland, Africa, and the 

 Northern Seas. 



52. Cypricardia. — Shell oblong, finely ra- 

 diated from the summit 

 to the base, equivalve, 



very inequilateral, bosses 

 very near one end, having 

 three cardinal and one lateral tooth in each 

 valve. Animal unknown. — 4 species recent, 

 7 fossil. 



Found principally in masses of coral in St. 

 Domingo, and on the coasts of Guinea and 

 New Holland. It also bores into soft stones. 



The genus Hiatella of Lamarck is no longer 

 used. The only species he mentions is found 

 to be a Saxicava. 



53. Isocardia. — Shell heart-shaped, equi- 

 valve, inequilateral ; 

 bosses very prominent, 

 rather spiral, recurved 

 in the same direction, 

 and not touching each 

 other ; cardinal teeth two, 

 lateral, one in each valve ; 



