202 



Merycociicerus. — Crowns of the molars proportionately longer than in 

 Oreodon, and protruding gradually as they were worn away ; the anterior 

 having their sculptured triturating surface obliterated before the posterior are 

 fully protruded. Anterior premolars with the length and breadth exceeding the 

 width, and the upper ones inclining posteriorly, and with their points in advance 

 of the middle. Facial cone aliruptly narrowed in advance of the orbits. 

 Infra-orbital arches deep and rapidly declining on the face. Orbits smaller 

 and more externally situated than in Oreodon. Infra-orbital foramen above 

 the interval of the tirst and second molars. Nasal orifice situated far above 

 the alveolar border, as in the tapir, and commencing below as an angular 

 notch of the premaxillaries, which are firmly co-ossified together and with 

 the maxillaries. Incisive foramen large. 



Meeychyus. — Teeth as in Merycochoerus. Facial cone intermediate in 

 character to the latter and Oreodon (?) Infra- orbital foramen situated above 

 the last premolar, or in a position intermediate to that of Oreodon and 

 Merycoehcerus. 



The more characteristic of the remains of Merycochajrus, from the Sweet- 

 water River, consist of fragments of jaws with teeth from perhaps a half 

 dozen individuals. One of the specimens consists of the greater part of an 

 upper jaw, represented in Figs. 1, 2, Plate III, accompanied with a portion 

 of the lower jaw, represented in Fig. 3 of tlie same plate. 



The face of Merycochoerus, as indicated by the upper-jaw specimen just 

 mentioned, would appear to difter in a remarkable manner from that of the 

 closely allied genus Oreodon. In the species to which the name of Merij- 

 cochcerus rusticus has been given, and which probably is the same as Mery- 

 chyus medius, the face is narrowed in the same abrupt manner in advance of 

 the orbits as in Merycochcems proprius. It is, however, more convergent than 

 in the latter, or is proportionately less widened at the extremity. 



The relation of the orbits and zygomata to the fore part of the face in 

 Oreodon is more like the condition in the peccary; in Merycochoerus more 

 like that in the hog. 



The side of the face in If. rusticus between the position of the 

 orbit and the prominence produced by the canine, and above the alveolar 

 ridge, is deeply concave, even more so proportionately than in the hog. In 

 M. propr'ms, it is not depressed in this manner, so that the side of 

 the face in the corresponding position is nearly vertical, and the large infra- 



