OF NEW TERTIARY FOSSILS. 131 



C. LicrATA. — PI. 14, fig. 20. — Suboval, thin and fragile, convex-depressed ; surface with minute, closely 

 arranged concentric lines ; anterior margin rather acutely rounded ; posterior margin obtusely rounded 

 or subtruncated obliquely outwards, the extremity rounded ; lunule lanceolate, defined by an obscure 

 line; beaks prominent and profoundly curved towards the anterior margin. Length 1. Height 

 8-10. 



Locality. Marlbourne, Hanover county, Virginia. Mr. Ruffin. 



This species is related to C. ovata, Rogers, but is more compressed, less dilated 

 posteriorly, the strise more numerous and distinct on the middle of the valves, while 

 the ovata has there only lines of growth. 



C. EVERSA. PI. 14, fig. 21. — Suborbicular or lentiform, ventricose ; surface with fine, closely arranged 

 concentric lines ; anterior and posterior extremities rounded ; basal margin profoundly rounded, and 

 forming a regular curve from the extremities ; umbo broad, with a prominent apex ; lunule ovate-acute, 

 marked by a well defined impressed line ; cardinal teeth robust. Length If. Height \%. 



Localitij. Marlbourne, Hanover county, Virginia. 



This shell has much the exterior aspect of an Artemis. Mr. Ruffin has one 

 specimen with both valves. It occurs at Marlbourne, the residence of Edmund 

 Ruffin, Esq., who is making important investigations in the Eocene deposits of that 

 locality. He has kindly sent me beautiful specimens of Cardita planicosta and 

 Cardiiim ISlicolleti, together with the new species of Cytherea above described. 



C. PYGA. PI. 14, fig. 18. — Suboval, ventricose, thick, with closely arranged robust concentric lines ; umbo 

 wide, prominent above ; dorsal margin very oblique, rounded ; posterior extremity obtusely and 

 obliquely rounded inwards ; anterior extremity much narrower than the posterior, and more acutely 

 rounded; lunule lanceolate, defined by a distinct impressed line ; cardinal teeth robust. Length If. 

 Height li. 



Locality. Potomac river, StaffiDrd county, Virginia. Mr. Bruff. 



I am indebted to Mr. Bruff, of Washington, for an opportunity to describe this 

 species. The specimen is a right valve, very perfect, and in outline has some 

 resemblance to C liciata, but is larger, thicker, more ventricose, with much wider 

 umbones, &c. 



NUCULA. 



N. iMPROCERA. PI. 14, fig. 23. — Elongated, very inequilateral, convex, polished, and having fine indistinct 

 concentric lines ; anterior side produced, bicarinated ; the upper margin incurved towards the apex; 

 extremity angulated. 



Locality. Marlbourne, Hanover county, Virginia. Mr. Ruffin. 



N. CLAiBORNENSis. — PI. 14, fig. 22. — Ovate-acute, compressed, polished, entire ; ligament and anterior 

 dorsal margins nearly rectilinear ; anterior side longest ; posterior end regularly rounded ; anterior 

 basal margin nearly straight. 



Locality. Claiborne, Alabama. 



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