1884.] 539 [Cope. 



foramina are well separated from each other, as in the species of Meryco- 

 choerus. The space between them is about equal to that between each 

 one and the superciliary border. There is a large postparietal foramen 

 near the parieto-squamosal suture. If the supraglenoid foramen be pres- 

 ent it is not distinguishable in the specimen. The orbit is rounded sub- 

 quadrate, with the inferior anterior angle a little produced. 



The ascending process of the mandible is relatively elevated. The 

 horizontal ramus narrows rapidly anteriorly, and the symphysis mandibuli 

 is produced so as to rise at a very low angle. The alveolar portion is 

 horizontal. 



The superior incisors are small and their apices are but little expanded, 

 the external the most so. They are directed vertically downwards. The 

 superior canine is quite small ; its crown exceeds in length that of the 

 first premolar by but little, and is directed a little posteriorly as well as 

 downwards. The roots of the first premolar are not as well distinguished 

 as in many other species, and are united in their extra-alveolar part at 

 least. The same is true of the second premolar. The apex of the cutting 

 edge is in line with the anterior border of the crown ; the rest of the edge 

 rises obliquely backwards. In the third premolar there is a slight bevel in 

 front of the apex, which is much better developed on the fourth. These 

 teeth are more truncate than the corresponding ones of the species of 

 Oreodon and Eucrotaphus, and the larger species of Merycochcerus. The 

 external faces of P-m. i and ii are convex ; that of P-m. iv is concave, 

 but without the reverted vertical borders seen in Oreodon culbertsoni. The 

 first true molar has long roots and a short crown. The last two molars 

 have crowns of a more elongate character, with well developed anterior 

 and middle ridges. The latter are not so prominent as those of the molars 

 of the Merychyus zygomaticus. 



The inferior incisors are directed upwards at an angle of about 30°. 

 They are similar and closely packed. The inferior canine is in close con- 

 tact with the third incisor, from which it differs in its larger, leaf-shaped 

 crown. The inferior first premolar is a slender one-rooted caniniform 

 tooth, with narrow crown and acute apex. The second premolar is one- 

 rooted, and has a leaf-shaped crown, with acute-angled apex. The third 

 is two-rooted, and has a wider and # nearly symmetrical crown. The fourth 

 is much larger, and its elongate crown laps inside of that of the third. 

 Its low angular apex is median. The last inferior true molar is dispro- 

 portionately larger than the others. No external cingula. 



Measurements of Skull. M. 



Length from occipital condyle to premaxillary border. . .161 



" " " " " postglenoid process. . . .030 



" " " " " postfrontal process. . . .078 



" " " " " preorbital border 130 



Diameters of orbit {vertical 0250 



*. transverse 0255 



