230 PAL^O-¥TOLOGY OF NEW JEESEY. 



more regular curve to the basal line. This species throws a little more light 

 on the characters of this genus than was known from the Cretaceous spe- 

 cies, as in the example figured on the plate, the entire hinge features can 

 be made out. These show that it is so very closely related to Nuculana as 

 herein used that it becomes a question if Nucidaria should be retained as a 

 distinct genus. It is possible there ma}" be some more distinctive feature in 

 the arrangement of the muscles, or in the form of the pallia! line, as these 

 features are not observable on the specimens; but so far as the characters of 

 the hinge-plate can be relied upon, I should not consider it a valid genus. 



Formation and locality, — In the upper layers of the Upper Marls, at 

 Shark River, New Jersey. 



Genus AXINEA Poli. 



Asiinea Couradi, n. sp. 

 Plate XXIX, Figs. 10 and 11. 



Shell small, the internal cast measuring a little less than one inch in 

 height, and is a trifle narrower than high. Valve depressed-convex, most 

 strongly convex above the middle, and gradually sloping below. Outline 

 nearly circular, equilateral, and slightl}^ pointed at the beak in the cast, bat 

 the outline of the hinge-plate would give a more circular form. Hinge- 

 plate narrow, marked on the anterior side by about eight short oblique teeth; 

 opposite side unknown. Muscular scars rather small. Exfoliated surface 

 marked by moderately fine, distinct, rounded striae. The margin denticu- 

 lated to correspond. 



The species diff'ers from A. Mortoni Conrad, from the Lower Marls, in 

 being less convex, and in being most convex above the middle, whereas that 

 one is evenly rounded. It also diff'ers in being higher than wide, that one 

 being the opposite, and in being more finely denticulate on the margin of 

 the cast. These diff*ei*ences I deem quite specific in forms of this genus. 



Formation and locality, — In the upper, stony layers of the Upper Marl 

 Bed, at Shark River, New Jersey. 



