210 



M. 



Depth of the maxillary at the condyle 0. Q27 



Depth of the maxillary behind the condyle 0. 023 



Depth of the maxillary near the middle , 0. 027 



Width of the ventral spine -■ 0.031 



This sj)ecies and the two preceding were not very unlike in size; the 

 two following are smaller. 



ICHTHYODECTES PROGNATHUS, Cope. 



Proceedings of the American Philosophical Society, 1870, November (Saurocepkahis) ; Haydon's Geologi- 

 cal Survey of Wyoming, &c, 1871, p. 417. 



In this species, the premaxillary is more rhomboid in outline than in the 

 others, and is less convex externally. Of its more numerous teeth, the first 

 is not larger than the last, differing thus from all others of the genus; it is in 

 line with the nearly straight anterior margin of the bone, and is more com- 

 pressed than in the other species. The surface of the bone is peculiar in a 

 minute sculpture of impressed lines, or lines of punctse. There is a very 

 small articular surface on the superior extremity. 



This species is represented by a premaxillary and attached proximal 

 portion of the maxillary bones of the right side, and by a large number of ver- 

 tebrae and other bones. These portions were associated in the collections 

 placed in my hands by Professor Mudge, and relate to each other in size, as 

 do those of the preceding species and the Iclitliyodedes ctenodon, 



The premaxillary is characterized by its great depth as compared with 

 its length, and by the shortness of its union with the maxillary. The pala- 

 tine condyle of the maxillary reaches a point above the middle of the alveolar 

 margin of the premaxillary. The latter contains alveola? of seven teeth, the 

 anterior of which only presents a perfect crown. It is elongate, compressed, 

 equilateral, smooth, and acute. Its direction is even more obliquely forward 

 than the anterior outline of the bone, which tself makes an angle of 50° 

 with the alveolar bonier. 



The vertebrae consist of ceryicals, dorsals, and caudal's, to the number 

 of about sixty, most of which are supposed to have been derived from the 

 same animal. The grooves are as in D. ■phlebotomus ; there being two below, 

 two on each side, and two above. The latter receives the bases of the ueu- 

 rapophyses, which are in many cases preserved. The inferior pair of grooves 

 becomes more widely separated as we approach the cervical series, leaving 

 an inferior plane, which is longitudinally striate-grooved. This plane widens 



