138 PALEONTOLOGY OF NEW JERSEY. 



Formation and locality. — In the Lower Green Sands of the Cretaceous 

 at Cream Ridge and MulHca Hill, New Jersey; and I have seen one very 

 fine internal cast from Delaware. 



Genus PACHYCAEDIUM Courad, 1870. 



(Am. Jour. Conch., Vol. V, p. 96.) 



Pachycardiujn Burlingtonense, n. sp. 



Plate XXI, Figs. 6 aud 7. 



Shell large and extremely ventricose, with large, strong, prominent, 

 and somewhat inflated beaks, which are strongly incurved and approxi- 

 mate. Valves inequilateral, the posterior side of the hinge line very much 

 elevated, and the postero-cardinal portion of the valves somewhat lobed; 

 height greater than the width; anterior side of the valves rounded fi-om the 

 hinge to the basal border; base regularly rounded, and the posterior side 

 somewhat straightened. Surface marked on the umbonal slope and pos- 

 terior side, extending to beyond the center of the valves by strong radii, 

 those along the umbonal slope being the strongest and of more than an 

 eighth of an inch in width on the type example. Other parts of the sur- 

 face marked by concentric lines which do not appear to have been strongly 

 marked. Hinge teeth very strong, their details cannot be determined from 

 the specimen. Muscular scars very large and deeply marked, projecting 

 on the cast, the posterior one largest. 



This shell has been retained in the collection of the Academy of 

 Natural Sciences at Philadelphia, under the name C. Spillmani. The shell 

 is, however, quite different in many particulars. It is not so elongate by 

 considerable, and the posterior side is distinctly lobed, and the form much 

 higher on the shoulder. The surface is radiated as far as the middle of the 

 valve, or beyond; although on the cast the markings are quite faint. In 

 its short, broad form and high postero-cardinal margin it is strongly marked. 



Formation and locality. — The specimen is marked with ink, on its sur- 

 face, "N. Jersey," and has all the lithological features of specimens from 

 near Burlington, New Jersey, being most likely from that place. 



