240 PALEONTOLOGY OF NEW JERSEY. 



from the Eocene sands of Claiborne, Ala., both in form, size, and surface 

 markings, but differs in being less attenuated behind, is rather more equi- 

 valve, with more prominent beaks, and the striae is somewhat finer. It is 

 possible it may not be a Corbula or that it may be a smooth species of Necera, 

 but it resembles Corbula more closely. The absence of angulation along 

 the posterior umbonal ridge, or of the corresponding truncation of the pos- 

 terior end, is against it being a true Corbula. 



Formation and locality. — In the upper layer of the Upper Marls, Shark 

 River, and at Dr. Kneiskern's pits. New Jersey. 



Genus NEEEA Grey. 



Nesera cequivalvis, ii. si). 

 Plate XXX, Figs. 20 and 21. 



Shell large for the genus, with very convex or almost inflated valves, 

 very nearly or quite of equal size, the apex of the beak only indicating any 

 inequality. Outline strongly ovate, large in front with a sharply rounded 

 anterior extremity and a slightly gibbous basal line; posterior end pro- 

 longed, narrow, and sharply rostrate. Beaks placed very far back, large and 

 inflated on the umbones, directed posteriorly, incurved and minutely pointed 

 at the apices, which are in close contact, or interlocking, that of the right valve 

 being in advance of the other. Lunule obsolete, but the escutcheon area 

 deeply impressed in the cast, representing a strongly inflected cardinal border 

 in the shell. Hinge-teeth unknown ; muscular scars and pallial line too faint 

 to be observed in the cast. Surface of the shell marked by very distinct, but 

 not strong, concentric undulations parallel to the margin of the valves. There 

 are very faint indications of radiating lines on the cast. I do not think, 

 however, that the}^ indicate radii on the shell, but only represent vascular 

 markings. 



The cast has exactly the form externally of Corbula CaroUnensis Con- 

 rad, as figured in the Appendix to the Report of the Geological Survey of 

 North Carolina, W. C. Kerr, Vol. I, page 11, PI. II, Fig. 15, and is almost 

 of the same size. 1 cannot think, however, that it has any relations to that 

 shell, for it certainly is not a cast of Corbula, and Mr. Conrad could never 

 have considered such a form as a Corbula when examining the shell itself 



