168 PALEONTOLOGY OF NEW JERSEY. 



The general expression of this shell when viewed externally is Mactra- 

 hke, and, were it not for a knowledge of the hinge, might readily be 

 supposed to belong to that genus; but internally the hinge differs very 

 materially. Dr. Stoliczka, in copying Mr. Conrad's generic description, 

 very properly corrects the V-shaped tooth of the left valve to an /\ -shape, 

 and places the genus under the Tellimdwj where it probably belongs, not- 

 withstanding its Madra-like appearance, as it does not possess an internal 

 cartilage plate. 



Formation and locality. — In the micaceous clays of the Lower Marls at 

 Haddonfield, New Jersey. Borrowed from the collection of the Academy 

 of Natural Sciences, Philadelphia. 



Genus ^NONA Conrad, 1871. 



(Am. Jour. Conch., Vol. VI, p. 74.) 



^nona Eufaulensis. 

 Plate XXIII, Figs. 2 and 3. 



Tellina Eufaulensis Conrad. J. A. :N". Sci., Vol. IV, p. 277, PL XL VI, Fig. 15. Gabb, 



Synopsis, p. 173. Meek, Check-list, p. 14. 

 Mnona Eufaulensis Con. Am. Jour. Conch., Vol. VI, p. 74. Stoliczka, Pal. Indica, p. 482. 



Shell small, triangularly ovate in outhne, three-fourths as high as long, 

 with the small beaks situated a little more than one-third of the length from 

 the anterior end. Cardinal margins rapidly sloping from the beaks, the 

 anterior most rapidly, and the anterior end sharph^ rounding just above the 

 basal line; posterior end more broadly rounded, but still narrowed; basal 

 hne broadly curved. Surface of the valve smooth and semipolished, the 

 disk rather highly convex for a Tellina-like shell, with very small pointed 

 beaks, a sUght angularity of the umbonal region just in front of it, and a 

 very narrow but distinctly circumscribed lunule. In the interior the hinge- 

 plate is very narrow, with a single small cardinal tooth in the right valve 

 and very small and narrow lateral teeth. Muscular markings unknown. 



This species differs from JEnona papyria Conrad, principally in the 

 even, smooth, or semi-polished surface, that one being without poHsh and 

 marked with uneven concentric lines of comparatively great strength; also 



