204 



with the other peculiarities of the face, may indicate that Merycochoerus whs 

 provided with large prehensile lips, or probably a short proboscis. 



As in Oreodon, the dental series of the upper jaw consists of 3 incisors, 1 

 canine, 4 premolars, and 3 molars ; of the lower jaw, 4 incisors, 1 canine, 3 

 premolars, and 3 molars. 



In both jaws of Merycochoerus, as in Oreodon, the teeth form nearly closed 

 rows. The largest interval is between the canine and first premolar of the 

 upper jaw, to accommodate the lower canine, which in all the Oreodont family 

 occupies a position behind the upper one. 



A last upper incisor, retained in the upper-jaw specimen of Merycochoerus 

 rusticus, resembles in its form and relative size to the others the correspond- 

 ing tooth in Merychyus elegans. 



In a fragment of a lower jaw represented in Fig. 5, Plate VII, and retain- 

 ing most of the incisors, the lateral one is observed to be much larger in re- 

 lation with the others than in Oreodon. Its crown, viewed in front, is nearly 

 ovoid in outline. Its borders are acute and meet in a rounded point. The 

 outer surface is convex. The inner surface, considerably shorter, is bounded 

 by a basal ridge. The intervening incisors, about half the size of the outer 

 one, successively but slightly decrease. Their crown is more truncate at the 

 summit, and the internal basal ridge is stronger. The large lateral incisor is 

 to be viewed as a modified canine in its relation with this tooth as present in 

 animals usually. 



The canines of Merycochoerus in all respects are like those of Oreodon. 

 As in this genus, the lower ones are to be viewed as modified first premolars, 

 assuming the form and function of canine teeth, but still holding in relation to 

 the other teeth the ordinary position of the former. 



The crowns of the premolars of M. rusticus in their earlier state are con- 

 siderably longer proportionately than those of Oreodon, and. by the time they 

 became wholly protruded they were so much worn as to have the peculiar 

 construction of their- triturating surface obliterated. 



The crowns of the upper premolars, except the last one, have a backward 

 inclination, successively increasing from the third to the first. The points 

 of these teeth occupy the anterior third of the crown in the earlier stage, 

 and at a late period become so advanced as to appear to form the anterior 

 corner of the crown. In Oreodon the corresponding teeth are nearly or quite 

 straight, and the summit of the crown is median, and continues so as the 



