CARBITA. 



GENERIC CHARACTER. 



Shell equivalved, inequilateral, thick, suborbicular, free, 

 regular, ribbed, the margin crenate ; epidermis distinct ; 

 hinge of two teeth, one of which is short, direct, and the 

 other oblique, elongated in one valve, and in the other 

 valve, is a large cardinal recipient cavity with an oblique 

 tooth on each side of it, nearly parallel with the margin ; 

 ligament subexterior; two obvious muscular impressions 

 united by an arquated, entire palleal line. 



OBSERVATIONS* 



Poli, informs us, that the animal resembles that of Ano- 

 donta and Unio ; and accordingly Blainville places the 

 genus next to that group with Venericardia and Cypricar- 

 dia as subgenera ; both of which Lamarck had separated 

 from Brugueire's genus Cardita. 



Venericardia is much like the present genus, with w hich 

 Sowerby unites it, and is chiefly distinguished by the teeth 

 being all oblique and directed towards one side. Cypri- 

 cardia is also very similar ; it is remarkably inequilateral 

 and has three teeth in each valve. Many of the species 

 of Cardita resemble Cardium on their exterior surface, but 

 the insulated lateral teeth of the latter are an obvious dis- 

 tinction. The three genera are certainly very closely alli- 

 ed in nature. 



P). 40. 



