.27 



OSTREA RADIANS. Tab. 13, fig. 1. 



Oblong, compressed, lobed and flexuous on one side ; the ribs 

 numerous, radiated; beaks very small, not prominent, pointed 

 and a little curved laterally. 



Localities. Vance's Ferry, 8. C.; . Claiborne, Alab. Mid- 

 dle Tertiary. 



This elegant species, remarkable for the regularity of the 

 ribs, was found in the former of these localities by my friend 

 Dr. Blanding, and others have come under my observation, from 

 Claiborne, where they form an entire bed or stratum, but are 

 almost all in fragments, firmly united by a calcarious cement. 



OSTREA SELLJEFORMIS, Tab. 13, fig. 2. 



Oblong, convex, thick and ponderous, lobed ; one side of the 

 larger valve profoundly sinuous and the opposite side gibbous ; 

 smaller valve sinuous and little convex ; dorsal margin long and 

 slightly arched, with both extremities obtusely rounded. 



Localities. Claiborne, Alab. Middle Tertiary. 



This singular shell does not vary greatly in its outline, and 

 is very unlike any other species of this country with which we 

 are acquainted. It is often extremely thick and ponderous. 



OSTREA CAROLINENSIS. Tab. 14, fig. 1. 



Obovate, oblique, thick, compressed; superior valve flat; in- 

 ferior valve convex, with concentric imbricated laminae which 

 are transversely plicated ; beaks broad and prominent ; fosset 

 large and defined by broad prominent lateral ridges. 



Locality. Santee Canal, S. C. 



A large and handsomely plicated oyster, having considerable 

 resemblance to O. compressirostra of Say, but the beaks in that 

 species are very small and compressed, whilst in the former 

 they are broad and prominent, and the shell attains a greater 

 size and thickness with an approach to a falcate form. 



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