426 CRETACEOUS PALEONTOLOGY. 



Inoceramus quadrans Whitfield. 

 Plate XXXIX., Fig. i. 



1886. Inoceramus Sagensis, var. quadrans Whitf., Pal. N. J., 

 vol. i (Monog. U. S. G. S., vol. 9), p. 79, pi. 14, fig. 

 16. 



1905. Inoceramus sagensis var. quadrans Johns., Proc. Acad. 

 Nat. Sci., Phil. (1905), p. 10. 



Description. Shell moderately convex, subquadrangular, 

 broadly subovate, the dorsal and ventral margins subparallel or 

 slightly diverging posteriorly. The beak large and prominent, 

 produced beyond the hinge-line. Anterior margin truncate to a 

 point below the middle, and forming with the hinge-line nearly 

 a right angle ; below the middle it rounds into the nearly straight 

 basal margin, which in turn posteriorly passes with a regular 

 curve into the posterior margin which is rounded below and 

 obliquely subtruncate above, meeting the posterior extremity of 

 the hinge-line in an oblique angle. The surface is marked by 

 somewhat irregular, subangular undulations which are more 

 crowded and less distinct towards the umbonal region, those on 

 the outer portion of the shell being rather widely separated. 

 "The middle of the cast for about two-thirds the width is marked 

 by strong, rather deep pits, connected by shallow furrows, show- 

 ing that the interior of the shell was covered with strong pearl- 

 like protuberances." (Whitfield). 



The dimensions of the type specimen are: length, 102 mm.; 

 height from hinge-line to basal margin, 78 mm. 



Remarks. Whitfield described this species as a variety of /. 

 sagensis, but it is so distinctly different from typical members of 

 that species that it seems to be well worthy of recognition as of 

 full specific rank. Furthermore, the sp'ecies of which he con- 

 sidered it a variety is not the true /. sagensis, but is here referred 

 to I. proximus. The species is especially characterized by its 

 truncate anterior margin and subquadrangular form. It has not 

 been met with in the recent collections. 



Formation and locality. Merchantville clay-marl (?),. Bur- 

 lington (Whitfield). 



Geographic distribution. New Jersey. 



