544 



OREODON OF NEBRASKA. 



The latter remain separated throughout life, and relatively to those of most 

 recent Ruminants, are very short. 



The nasal bones are of nearly uniform breadth, and posteriorly are received in a 

 deep angular notch of the frontals. 



The palate plates of the palate bones advance as far as a line transverse to the 

 first true molars, or even a little anterior to them. 



The intermaxillary bone is very much shorter than that of existing Ruminants, 

 or even that of Carnivora, to which it has a strong resemblance at its lower part. 

 Its process upwards is short, and is received by the apex into a notch of the supe- 

 rior maxillary bone, and, so far as can be ascertained in the specimens, does not 

 come in contact with the nasal bone. 



Inferior maxilla. — (Tab. x., fig. 5.) The lower jaw of Oreodon resembles more 

 that of the Hog in its general form than of any of the existing Ruminants, excepting 

 that the canine and incisive alveoli retain an upward direction like the molars. 



The body of the lower jaw is relatively deeper than in the Deer, and its base is 

 more nearly straight. Its outer side is vertical, and very slightly convex. Ante- 

 rior to the mental foramen, which is placed just below the second premolar, or the 

 interval between it and the first, it rapidly converges to the symphysis. The latter 

 is deep, and forms a strong slope, but approaches the vertical line even more than 

 in the Hog. 



The alveolar margin ascends so rapidly posterior to the fourth premolar, that the 

 body of the jaw behind the last true molar is more than half as deep again as it is 

 below the former tooth. 



The ramus is very broad, and vertical externally. At its upper part, below the 

 post-coronoid notch, it is deeply depressed relatively to the condition of the same 

 part in existing Ruminants. 



The posterior margin of the lower jaw, a short distance below the condyle, in 

 conjunction with the angle and bottom of the ramus forms a thick, strong convexity, 

 prominent backwards and downwards, and also elevated externally for the attach- 

 ment of the masseter muscle. 



The coronoid process is almost as short as in the Hog, and the condyle has the 

 same relative position to its base as in the latter animal. 



Dentition. — The formula of the permanent dentition of Oreodon is, — in. can. ^, 



premol. mol. |?, = 44. 



The superior molar teeth (Tab. x., 4, 5 ; xi., 2, 3) on each side, internally, are 

 nearly parallel. They form a continuous row, and are separated from the canines 

 by a hiatus, not greater than the antero-posterior diameter of the first premolar, for 

 accommodating the inferior canine. 



Laterally the superior incisors are in contact with the canines, but in some cases 

 are separated by a slight hiatus. They project vertically downwards, and are 

 arranged in the tangent of a considerably greater circle than that of the Wolf. 



The inferior molars are also very nearly parallel on both sides. They form a 

 continuous row, with the canine included. Anterior to the latter, between it and 

 the incisors, is a hiatus for accommodating the superior canine, but less in size even 

 than that behind the last-mentioned tooth. 



