i2 4 CRETACEOUS AND TERTIARY FISH. 



Mandibular with long and straight beak, and outer face con- 

 cave to base of anterior outer dentinal area. Long axis of jaw 

 straight, also inferior border. Inner dentinal area undivided, 

 transversely thickened, narrow and extending to inner edge of 

 superior face of mandible. Anterior outer dental area not pro- 

 duced anterior to border of inner area, not on a projection, and 

 not extending as far as inner. Apical area end of a curved lami- 

 nar column. Length ioo mm. (From Cope.) 



This species was originally described by Marsh from an 

 ichthyodurlite he assigned to a chimaeroid fish. It was a nearly 

 perfect dorsal spine about 356 mm. long, somewhat curved, re- 

 markably slender, tapering regularly to its apex, compressed 

 transversely, outline generally suboval, posterior surface slightly 

 concave in lower portion, upper half of this surface armed with 

 two rows of very sharp decurved teeth while corresponding part 

 of anterior face had sharp cutting-edge finely serrated toward 

 distal end, and sides of spine smooth or faintly striated. He 

 also noted that fragments of this species of much larger size 

 were not uncommon in the same geological horizon in other 

 parts of the State. 



Formation and locality. Cope had a broken mandible and a 

 dorsal spine, which latter he thought identical with the one 

 noticed by Marsh. All the material examined by these two 

 writers was from the upper Cretaceous marl bed near Horners- 

 town [the Hornerstown marl] in Monmouth County (J. G. 

 Meirs). The identity of the mandible, described above from 

 Cope, must be considered provisional, resting entirely on the fact 

 that it was topotypic and has not been demonstrated positively 

 to belong to the same fish to which the ichythodorulite belonged. 



Edaphodon divaricatus (Cope). 



Ischyodus divaricatus Cope, Proc. Boston Soc. Nat. Hist., XII, 1869, p. 315. 

 Cretaceous marl of Burlington Co., N. J. 

 Cope, Rep. U. S. Geol. Surv. Terr., II, 1875, PP- 2^5, 292. (New Jersey 

 greensand, No. 5, from near Hornerstown.) 



Right mandibular a trifle more than twice as long as deep, 

 and rami would apparently converge in a slight curve, nearly an 



