LAMELLTBEANCniATA OK THE LOWER MAELrf. 83 



extremely ventricose and about onL--fourth longer than high. Area very 

 wide and apparently three-fourths as long as the body of the shell. Ante- 

 rior end abruptly rounded backward from the extremity of the hinge, and 

 the posterior end obliquely truncated, being longest at the postero-basal 

 angle, which is somewhat rounded. Basal line very gently arcuate, but not 

 at all sinuate or with the margins gaping. Muscular scars rather small, and 

 not very distinctly marked. Surface features and hinge of the shell 

 unknown. 



A single internal cast of this species only is known. It presents very 

 strong affinities with Area quinquedecemradiata Gabb in nearly every par- 

 ticular, except in being very much smaller than the majority of that species; 

 and were it not for the locality assigned to it (Crosswicks, N. J.), which 

 would bring it in the Lower Cretaceous strata instead of at the very summit 

 of that formation, as is the case with A. quinquedecemradiata, I should be 

 very strongly inclined to consider it as only an immature or perhaps a 

 dwarfed specimen of that species; but if the geological horizon is correctly 

 assumed it might, on the examination of the exterior, whenever found, 

 prove to be a distinct species. Therefore I have preferred to leave it as 

 such until further information is obtained. 



Formation and locality. — The sjjecimen is in the collection of the Acad. 

 Nat. Sci., Philadelphia, and is labeled "Crosswicks, N. J.," on what authority 

 I cannot say, as the original label belonging to it does not bear any locality 

 mark other than the letters "N. J." 



Genus NEMODON Conrad. 



(Am. Jour. Conch., Vol. V, p. 97.) 



Nemodon Eufaulensis. 



Plate XII, Figs. 3-5. 



Area (Macrodon) Eufalemis Gabb. J. A. N. S. Phil. 2d ser., Vol. IV, p. 398, PI. LXVIH, 



fig. 38; Synop. p. 96. Meek, Geol. Kept. N. Jersey, 1868, p. 725. 

 Trigonoarca Eufalensis (Gabb) Conrad. Am. J. Conch., Vol. Ill, p. 9. 

 Nemodon Eufalensis (Gabb) Conrad. Am. Jour. Conch., Vol. V, p. 97, PI. IX, Fig. 16. 



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 ob- 



