MOLLUSCA. 385 



Super-family ARCACEA. 

 Family PABALLELODONTODAE. 



Genus NEMODON Conrad. 



Nemodon eufaulensis (Gabb). 



Plate XXX., Figs. 8-n. 



1860. Area (Macrodon} eufalensis Gabb, Jour. Acad. Nat. Sci. 



Phil., 2nd ser. vol. 4, p. 398, pi. 68, fig. 38. (Not 

 Nemodon eufaulensis Con.) 



1 86 1. Area Eufalensis Gabb, Synop. Moll. Cret. Form., p. 152 



(96). 



1868. Area Eufalensis Con., Cook's Geol. N. J., p. 725. 

 1886. Nemodon Eufaulensis Whitf., Pal. N. J., vol. i (Monog. 



U. S. G. S., vol. 9), p. 83, pi. 12, figs. 3-4 (not fig. 5). 



Description. "Shell small, seldom reaching a length of one 

 inch in the extreme. Form trapezoidal, the cardinal and basal 

 margins subparallel, and the length about twice and a half as 

 great as the height. Anterior end obliquely and rapidly reced- 

 ing from the extremity of the hinge and most rapidly on the 

 lower half; posterior end obliquely truncate, prolonged back- 

 ward below to the umbonal angle. Valves moderately ventricose, 

 with a decidedly angular umbonal ridge behind, and a shallow 

 mesial depression extending from the beaks to the basal border, 

 slightly affecting the basal line near the middle of its length. 

 Beaks large and rather prominent, situated at about the anterior 

 third of the length. Area moderate. Surface marked by 

 numerous fine radiating striae showing upon the cast, which are 

 a little coarser near the posterior angle and on the cardinal slope, 

 possibly somewhat alternating in size on the anterior end, but 

 indistinctly showing this feature on the internal cast. Hinge- 

 line marked by two distinct linear teeth on the anterior end par- 

 allel to the hinge. Those of the rest of the hings have not been 

 observed." (Whitfield.) 



Remarks. The Haddonfield specimens referred to this species 

 by Conrad and made the type of the genus Nemodon, are con- 

 25 PAL 



