DINOCEEATA. 597 



Osborne to be represented by a mere convexity. In Uintatherium, Marsh 

 has discovered it to be confined to the anterior part of the jaw, as in the 

 saber-tooth cats. In Bathyopsis it extends to the entire length of the ramus, 

 giving an outline in profile much like that of 3Ie(/atherium. The anterior 

 extremity of the symphysis projects beyond the line of the anterior border 

 of the inferior expansionr 



The characters of the inferior molars in this and other genera of Dino- 

 cerata are very peculiai-. In Bathi/opsis they are constructed on the plan of 

 those of insectivorous marsupial and placental mammals, so as to lead to 

 the suspicion that its food consisted of Crustacea,, or insects of large size, or 

 possibly of thin-shelled moUusca. 



Bathyopsis pissidens Cope. 



Loci supra cilali. 

 Plate XXIX b, figs. 1-3. 



The lower jaw is not much larger than that of the Malayan tapir, but 

 as this part of the skull is disproportionately small in this order, it is prob- 

 able that this species is of considerably larger size than the one mentioned. 

 The symphysis mandibuli is quite narrow, and its superior excavation is 

 deep. It extends as far posteriorly as the middle of the diastema. It has 

 considerable vertical thickness. The anterior edges of the lateral expan- 

 sions are truncate, and present an obtuse angle outward, which forms the 

 anterior boundaries of the slight concavity of the lateral face. The middle 

 of the expansion below the first premolar tooth is slightly convex. This 

 wall incloses a large internal expansion of the dental canal, which issues 

 in a large mental foramen. This foramen is situated near the middle of the 

 vertical diameter of the expansion, and below the anterior part of the 

 diastema. It looks downward and forward. The external face of the 

 posterior part of the ramus is nearly plane The inner face is vertical to a 

 line which corresponds with the inferior border in Coryphodon^ and then 

 slopes obliquely outward to the inferior margin. The base of the coronoid 

 process rises vertically from the line of the alveolar border, and its external 

 edare forms an anterior border for the masseteric fossa. The inferior border 



a 



of the fossa is not defined. The inferior border of the ramus is decurved 

 posteriorly, and projects inward considerably beyond the plane of the jaw. 



