PLEIOCENE FOSSILS. 19 



This very irregular shell is abundant in the marls of the State, and particularly on the 

 Waccamaw river. The upper valves often occur in great numbers, one within the other, as 

 shells are frequently seen along the coast, thrown up by the waves. The lower valve, which 

 is more fragile, is rarely found fossil. 



It is the only species in the upper tertiary of South Carolina. The genus Anomia, at 

 present an inhabitant of every sea, occurs in the fossil state as far back as the cretaceous 

 period. 



Plate V., Fig. 4. Upper valve, natural size. 

 " 5. Side vieiv, natural size. 



Locality. Waccamaw. 



Museum, College of Charleston, S. C. 



PLACUNANOMIA.— Brod. 



PLACUNANOMIA PLICATA.— {New Species.) 



P. testa subov ali, subequivalvi, subequilaterali, subfoliacea, tenui j rnargine ter plicata, im- 

 pressione musculari magna, semiorbiculari, centrali • valva superior e versus car dinem plana ; 

 costis cardinalibus aliquantulum divergentibus. 



Description. Shell sub-oval, but variable, sub-equivalve, sub-equilateral, slightly foliated, 

 thin, margin with three or four deep plications ; muscular impression large, semi-orbicular 

 central ; upper valve flat near the hinge or beaks ; the two ribs in the hinge slightly 

 divergent. 



We believe this to be the first of the genus that has been found fossil in the United 

 States. In the cabinet of Dr. Edmund B,avenel, of this State, there is a species taken from 

 the harbour of Charleston, belonging to this genus. It is, therefore, living upon the coast 

 of South Carolina. 



Plate VI. , Fig. 4. Upper valve, natural size. 



" 5. Inside of lower valve, showing the costal ribs of the hinge, the muscular im- 

 pression, and the perforation for the passage of the organ of attachment. 

 " 6. Side view of the fossil, natural size, showing the plicated margin. 



Locality. Smith's, Goose Creek. 



Museum, College of Charleston. 



