54 Bui^i^ETiN 5 334 



FOSSIL SHELLS. 



lunule : within crenate on the edge : posterior mus- 

 cular impression rectilinear. 



Length half an inch, breadth eleven-twentieths 

 of an inch. 



Two or three smaller specimens are two-fifths 

 of an inch long. In the outline of the edge, and 

 number of the costae, this species approaches the 

 ly. scabra of authors ; but it is more convex, and 

 in other respects sufficiently distinct. In the larger 

 specimens, the transverse lamellae are almost ob- 

 solete at base, and the ribs prevail in that part. 



ly. divaricata. Var. The fossil specimens of 

 Maryland are altogether similar to those found at 

 present in a recent state on our southern coast. 

 This variety is smaller than those of South Ame- 

 rica and the West Indies, and the lateral teeth are 

 more obvious. In the collection of the Academy 

 is a large specimen of the divaricata from the 

 West Indies, that agrees with the description of 

 the dentata of Wood. I should therefore be in- 

 clined to suppose, that the dentata is no other than 

 a variety of the former, owing to age. 



VENUS. 



I. V. deformis. PL xii. fig. 2. a. View of the 

 hinge. Shell remarkably thick and ponderous, 

 longitudinally undulated ; basal margin undulated. 

 Description. Shell subcordate, with transverse 

 wrinkles, which are distant and regular on the 

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



