207 



Portheus. The margin rises steeply to the dentary, which presents a nar- 

 rowed rectangle behind. The alveolar margin has two convexities, with a 

 depression between ; the symphyseal angle is not prominent. The lower 

 posterior angle of the dentary is quite prominent for muscular inserlion. The 

 crowns of the teeth arc cylindric, slightly curved inward. The dentary bones 

 of the second specimen coincide with these in all respects. 



Thirty-three vertebra are preserved, all deeply two-grooved on the sides. 

 The ribs are articulated by a sigmoid surface to a broad, short element of a 

 sigmoid form, which is inserted in the lateral groove of the inferior face, or 

 articulated by gomphosis. 



The ventral spines already noticed are quite flat, without serrate edge, 

 but with some rugosities near the edge on one side only. There are no grooves 

 on the upper side, but the dense bone is delicately striate. 



Measurements. 



M. 



Length of the preruaxillary 0. 033 



Depth of the pre maxillary 0.045 



Depth of the maxillary at the condyle 0. 037 



ThickDess of the maxillary just behind the condyle 0.012 



Length of the mandibular ramus 0. 172 



Length of the angular process 0. 014 



Depth at the coronoid process 0. 058 



Depth at the symphysis 0. 04 1 



Length of eight vertebrae , 0.212 



Width of the articular face 0.030 



Width of rib -. 0.004 



Width of the ventral spine at the middle 0. 025 



Length of the ventral spine (fragment) 0. 155 



Length of the condyle of the inferior quadrate 0.020 



The scales associated with this species were tJiin and cycloid, and diffi- 

 cult to preserve. 



From near the Smoky Hill River, Kansas. 



ICHTHYODECTES CTENODON, Cope. 



Proceedings of the American Philosophical Society, 1870, November ; TIayden's Geological Survey of Wy- 

 oming, &c, 1871, p. 421, part. 



Found by Professor Mudge on the North Fork of the Smoky Hill River; 

 common in many other localities. 



This species is established on one complete maxillary bone, and three- 

 fourths of the other, a large part of the dentary bone, with the entire dental 

 series, and numerous portions of cranial bones. These, according to Profes- 

 sor Mudge, were found together, and, to all appearance, belong to the same 

 animal. 



