203 



orl)ital foramen opens forward on this vertical surface. In M. rusticiis^ I lie 

 infra-orbital foramen is also large, and occupies a corresponding position, \n\i 

 is situated in the concavity of the side of the face, so that the surface of the 

 alveolar border curves outwardly and downward from it. 



The front of the snout or fore part of the upper jaw resembles in its con- 

 struction the same part in the tapir more than that of Oi-eodon, but, as in the 

 latter, it barely projects beyond the position of the canine alveoli. The pre- 

 maxillaries are completely co-ossified with each other and with the maxillaries. 



Viewed at the side, the fore part of the upper jaw is convex forward and 

 downward, as in the tapir. Viewed in front, (Fig. 2, Plate III,) it presents a 

 long slope, narrow above, widening below, depressed toward tiie median line, 

 and bounded laterally by the convex curved prominences of the canine 

 alveoli. About 1 J inches above the alveolar margin the nasal orifice com- 

 mences in an angular notch as in the tapir, but proportionately less narrow. 



Behind the position of this nasal notch, bordered by thickened ridges 

 ascending in a convergent manner from the canine alveoli, are the lateral con- 

 cavities of the face before mentioned. 



The upper part of the face being broken away, we can form no just idea 

 of its character. If constructed as in Oreodon, by the conjunction of the 

 maxillaries along the course of the nasals, it would appear to be exceedingly 

 narrow, even less than half the width at the alveolar border. It would appear 

 as if the construction might be somewhat similar to that in tlic tapir, so that 

 the maxillaries bounded a large nasal aperture overhung by the nasals. 



The infra-orbital arch is nearly twice the depth it is in Oreodon, and resem- 

 bles in its proportions that of the hog. Its outer surface is nearly vertical or 

 slopes slightly outward, and is nearly plane or slightly depressed. The ante- 

 rior zygomatic root is an unusually prominent process of tlie maxillary. Its 

 sutui'e of conjunction with the malar descends nearly on a line with the an- 

 terior border of the orbit. The latter is smaller, and is situated more exter- 

 nally than in Oreodon. 



Tiie roof of the mouth is moderately concave, and the incisive foramen, 

 apparently, is proj^ortionately as large as in the tapir. 



The lower jaw of Merycochcerus is like that of Oreodon, and, as in this and 

 all living ruminants, has the rami united by suture. 



The mental foramen, like the infra-orbital foramen, is proportionately larger 

 than in Oreodon. Perhai)s this difference in the size of the ii)ranii:)a, tog<;ther 



