38 OREODON. 
rior to the lower canine, a hiatus of sufficient size to accommodate the cusp of the 
upper one. This hiatus is in a trifling degree less than that posterior to the upper 
canine. ’ 
The inferior incisors are oblique in their position, but relatively, less so even than 
in the Musks; and they form a longer arc of a lesser circle than those of the upper 
jaw. 
When the jaws are closed, the inferior molars are situated within the line of the 
outer lobes of the upper true molars, but anteriorly they are placed very little within 
the outer faces of the upper premolars. 
The intervals between the pyramidal crowns of the premolars are triangular, 
and the three inferior crowns are included by the four superior ones. 
The crown of the superior canine is directed downward and outward, and, as 
in the genus Puleotherium, it is placed in advance of the canine below; a position 
which is exceedingly anomalous. Its point projects considerably exterior to the 
inferior canine, and only its internal angular margin occupies the hiatus in advance 
of the latter tooth. 
The crown of the. lower canine is directed upward, and a little forward and 
outward; and its point, though projecting slightly exterior to the hiatus provided 
for it above, is yet within the line of the outer surface of the upper canine. 
The inferior incisors, laterally, are included within the circle of the superior; 
while the cutting edges of those anterior come in contact with the edges of the 
corresponding teeth above. The outer sides of the upper incisors are vertical, and 
those of the lower incisors incline to them at an angle of about 50°. 
Superior Molars.—(P1. IL. Figs. 1, 3; III. 1,2; 1V.6; V. 2,3; VI.2,3,4,6.) The 
crowns of the upper true molars are composed of four symmetrical lobes, as in all 
existing ruminants. Among these, they approach most in their form the crowns 
of the corresponding teeth of the Deer, but they are more expanded trans- 
versely, and more square, the interlobular depressions more shallow, and the 
inner lobes are uncomplicated with accessory folds or lobes. Among the extinct 
ruminants of which we have any knowledge, they resemble most those of 
Merycopotamus ; but they differ from the teeth of this genus in a number of par- 
ticulars, more especially in the non-isolation of the outer lobes (which conjoin 
in a prominent buttress, as in Anthracotherium), and in the relatively slight degree of 
development of the basal ridge, which does not traverse the bottom of the trans- 
verse interlobular space, as it does in the Merycopotamus. _ From the corresponding 
teeth of Anthracotherium, Hyopotamus, and Caenotherium, they differ most in the 
absence of the fifth constituent lobe, which in the former two genera is introduced 
between the anterior pair of normal lobes, and in the last genus between the poste- 
rior pair. From those of Dichodon, they differ in the absence of the curiously 
cuspidate basal ridge, and in the less acuteness of the lobes. Finally, from the true 
molars of the most aberrant forms of extinct ruminants, the Anoplotherium and 
Chalicotherium, they differ as characteristically as do those of any of the existing 
members of the family. 
When unworn, the lobes of the true molars have acute crescentic summits 
elevated to a middle point. The outer lobes anteriorly, and consequently 
