48 Buj^LETiN 5 318 



142 FOSSIL SHELLS. 



rounded lines : beaks rather behind the middle : 

 ligament margin a little concave : series of teeth 

 angulated at the beaks. 



Length over one-fifth, breadth two-fifths of an 

 inch. 



The regularly striated surface gives this shell a 

 very pretty appearance. In outline it has some 

 resemblance to the rostrata. 



VENERICARDIA. 



V. gramdata. PL xii, fig. i. Suborbicular, with 

 about twenty-five convex ribs, and wrinkled across ; 

 inner margin crenate. 



Description. Beaks nearly central, a little pro- 

 minent, curved backward : ribs granulated on the 

 umbones, and transversely wrinkled near the base, 

 convex : apices somewhat prominent beyond the 

 general curve of the shell : inner tnargin and edge 

 crenate : cardinal teeth two. 



lyength from the apex to the base four-fifths of 

 an inch, breadth nearly the same. 



Rather proportionally longer than the decussata, 

 and more oblique. 



CRASSATELLA. 



C. undulata. PL xi. fig. 2. a. External view^ 

 b. Internal view. Much compressed, transversely 

 oblong-subovate, slightly angulated before ; surface 



[J. A. N. S., Phila., ist Ser., Vol. IV, 1824.] 



