MOLLUSCA. 597 



largest observed. The character of the surface markings is shown 

 in several natural impressions of the exterior. 



Formation and locality. Merchantville clay-marl, near Mat- 

 awan (ioo 4 ), near Jamesburg (140). 



Geographic distribution. New Jersey. 



Genus FULVIA Gray. 



Fulvia tenuis Whitfield. 



Plate LXVL, Fig. 8. 



1886. Fulvia tenuis Whitf., Pal. N. J., vol. i (Monog. U. S. 

 G. S., vol. 9), p. 139, pi. 20, fig. 8. 



Description. "Shell rather small, but little exceeding an inch 

 in length by about half that height ; transversely elliptical in out- 

 line, and but moderately convex. Beaks very small, appressed, 

 and but very slightly projecting beyond the hinge margin. An- 

 terior end of the shell the shortest, obtusely pointed, or sharply 

 rounded at its extremity, which is situated much above the middle 

 of the height; posterior end more broadly rounded; basal line 

 strongly arcuate and rapidly ascending toward the anterior part. 

 Hinge-line but little declining on either side of the beak. Surface 

 of the valve marked by radiating plications which are very fine at 

 the anterior end, and gradually increase in strength to the extreme 

 posterior margin, where they must have been fully one-sixteenth 

 of an inch wide (the shell being broken at this point). Plications 

 flattened obliquely, so as to give the anterior side a much greater 

 abruptness and only about one-third the width of the posterior 

 side. A few concentric undulations mark the surface, and very 

 fine concentric striae cover the entire shell." (Whitfield.) 



Remarks. This species was established by Whitfield upon a 

 single, rather imperfect cast of a right valve, and no additional 

 specimens have been met with in the more recent collections of 

 the Survey. 



Formation and locality. Navesink marl, Holmdel (Whit- 

 field). 



Geographic distribution. New Jersey. 



