Cope.] 314 [February 17, 



of the same element of Edapliodus and Ischyodus, but it -differs in the 

 presence of only two very narrow dentinal bands, which are opposite 

 and parallel, one on the outer margin, and the other within the inner 

 margin of the 'bone. The form is much depressed and spade-like, 

 the superior face scarcely descending regularly to the edge. The 

 outer margin expands an inch behind the extremity, and is bevelled 

 off fi'om the continued width of the upper face. The latter exhibits 

 slight longitudinal strife. It presents proximally the usual large 

 groove. 



Lines. 



. Width at extremity 14 



Depth on inner margin 3| in. from anterior extremity . 9 



Length of inner dentinal patch 16 



" outer " " 11 



ISCHYODUS. 



I. Inner posterior dentinal area divided into three parts. 

 Inner symphyseal surface barely reaching anterior dentinal area; 



posterior outer crest with small area /. mirificus. 



II. Inner posterior dentinal area undivided. 



a. A posterior outer crest with large area. 

 Areas very large, marginal; body of maxilla contracted to a verti- 

 cal edge behind; symphysis very short, straight. . • . I. Smockii. 

 a a. No posterior outer marginal crest. 

 Anterior outer area oval, not marginal, short; the inner wide, in 

 two planes, the inner descending on the margin and reached by inner 



symphyseal face I. monolophus. 



a a a. Neither anterior nor posterior outer marginal crests distinct. 



Anterior outer area very small, the posterior large; the interior 



very large and oblique transversely ; beak twisted out of the planes 



of the body of the maxillary /. divaricatus. 



Ischyodus monolophus Cope. 



This species is represented in my collection by two inferior maxil- 

 lary pieces from opposite sides, which were found in the Green-sand 

 near Bamesboro', Gloucester Co., N. J. They did not belong to the 

 same individual, as one exceeds the other in its dimensions. Besides 

 the characters pointed out above, it is to be added that a small denti- 

 nal column opens on the symphyseal face opposite the middle of the 

 inner posterior area, perhaps a little larger than one in the same 



