103 



and as far south as East Florida. Cabinet of the Academy and 

 Philadelphia Museiim. 



Yeiy distinct from the preceding species, and probably approaches 

 L. crassiplica of Lamarck. 



CoRBULA CONTRACTA. — Shell transversely subovate; valves 

 subequal, regularly and profoundly striated transversely ; beaks 

 not prominent, nearly central, one side rounded and the other sub- 

 acute ; basal margin contracted near the middle, and one half of 

 the length of the edge of one valve concealing one half of the 

 edge of the opposite valve. 



Length one-fourth of an inch. Breadth two-fifths of an inch. 

 Thickness one-fifth of an inch, nearly. Inhabits the coasts of 

 Georgia and East Flarida. Cabinet of the Academy and Phila- 

 delphia Museum. 



I found two specimens of this shell. The strige are precisely 

 similar to those of the larger valve of Mi/a irisequivalvis of Mon- 

 tague ( C. nucleus of Lam.) 



Mya acuta. — Shell oblong-subovate, narrowed behind, rather 

 strongly wrinkled ; posterior hinge margin and posterior basal mar- 

 gin subequally arquated ; tip of the posterior margin equidistant 

 from the apex and middle of the base ; tooth moderate, with a 

 small, not prominent, tooth on its posterior side. 



Length one inch and a half. Breadth two^^inches and four-fifths. 

 Inhabits the southern coast. Cabinet of the Academy and Phila- 

 delphia Museum. 



I have but two valves, which are old and bleached. It resem- 

 bles M. arenaria, but is much smaller at the posterior termination, 

 than the con-esponding part of that shell, as figured by Bruguiere. 

 One of the valves alluded to is more than four inches in breadth ; 

 it corresponds very well in the outline with Pennant's fig. of 

 arenaria. My decorticated specimens have an obsoletely radiated 

 appearance. 



Mya mercenaria. — Shell subovate, convex, somewhat un- 

 equal, transversely wrinkled; posterior hinge margin curving 

 abruptly downward to the tip of the posterior margin, which is 

 much nearer to the middle of the base than to the apex; tooth 

 robust, prominent, very convex within, and with a small tooth on 

 its posterior side ; within white. 



