87 



4. C. diftcoidalis. PI. 19. fig. 4. 



Shell ventricose, thick, suborbicular, gradually narrowed to 

 the beaks, with concentric striyo rather deeply impressed, giv- 

 ing the shell a rough exterior : beaks anterior to the middle ; 

 inner margin crenulated ; lunule cordate, not very distinct. 

 Diameter 1 inch. 



Locality. Claiborne, Alab. 



Cab. Acad. N. S. 



, r >. C. perovata. PI. 19. fig. 5. 



Shell cuneiform-ovate, convex, smooth* and polished, 

 slightly sulcated on the inferior half of the valves; posterior side 

 slightly compressed and cuneate ; umbo tumid, beaks almost 

 anterior; two anterior cardinal teeth in the right valve, ap- 

 proximate and parallel; lunule cordate and defined by a sim- 

 ple depressed line. Length 1] inches. Breadth 1 inch. 



Locality, Claiborne; Alab. 



Cab. Acad. N. S. 



J* NUCULA. 



N. wagnifica. PI. 20. fig. 3. 



Shell obliquely subtriangular, very inequilateral, smooth, 

 thick, with obscure reticular striae ; anterior side truncated ; 

 posterior side elongated or cuneiform ; basal margin crenated : 

 hinge* teeth elongated ; within pearly or purplish. Length 

 nearly of an inch. * * 4 ~ 



Locality, Claiborne, Alab. 



Cab. Acad. N. S. ' * 



;-* ; ARCA. 



Area cuvuUoides. PI. 20. fig. 1. 



Shell compressed, thick, inequi valve, reticulated; with a 

 broad subcentral sinus, passing from the beak to the basal 

 margin : posterior side elongated, strongly ribbed, and carina- 

 ted ; anterior side with numerous striae; anterior end trunca- 

 ted. Length 2$ inches. Breadth H inches. 



The hinge of this shell approaches cucullaaa, in the interval 

 between the beaks, having arcuated grooves under the beak; 



