MUSEUM OF COMPARATIVE ZOOLOGY. 167 
skull with the greatest diameter horizontal (Fig. 7). The squamosals are 
low and widely united with the parietals. The articular facets for the mandi- 
ble and post-glenoid processes resemble those in the rhinoceros, on a larger ° 
scale. The parietals are rather short, a considerable portion of the cranium 
being formed by the supra-occipitals. The occiput is low and broad, with 
powerful condyles, which are much extended transversely. The space between 
the condyles and post-glenoid processes is rather short. The paroccipital and 
post-tympanic processes are on a level and closely united. The latter forms a 
wide union with the post-glenoid, completely enclosing the external auditory 
meatus inferiorly. The basi-occipitals and sphenoids form a prominent ridge, 
which is not overlapped anteriorly by the pterygoids. These bones are rather 
short and obtuse. This region of the skull is, upon the whole, very similar to 
that of the rhinoceros. The relations of the bones composing the hard palate 
are also rhinocerotic, except that the incisive alveolus is much shorter. 
DENTITION. 
Lower Jaw. The crowns of the entire mandibular series are wanting. There 
were three lower incisors, which, so far as we can judge from the alveoli, were 
smaller than the upper, and much crowded by the large canines. The lateral 
incisor was the largest, the series decreasing towards the middle line. The 
canine fang is completely preserved, and indicates a large, semi-procumbent, 
laterally compressed tooth, measuring 14 inches in transverse diameter. It is 
followed by a diastema of twoinches. The first and second premolars are want- 
ing; the third has two fangs, and has about half the antero-posterior diameter 
of the first molar. The fourth premolar is two thirds the diameter of the first 
molar. The three molars increase rapidly in size, covering a space equal to 
that occupied by the upper molars, and three times that occupied by the 
premolars. The last molar is the largest, and was apparently trilobed. 
Upper Jaw. The mazillary series are better preserved, the inner faces of 
the molar crowns showing on one side or the other in all except the first and 
last of the series. The zncisors were placed in a uniform curvature, the lateral 
incisor being separated from the canine by a narrow diastema. The median 
alveolus is the largest, and the series apparently decreased in size laterally, 
reversing the relations of size shown in the mandibular series. The canines 
were subequal in size, and inclined forwards like those in the mandible. A 
narrow diastema separates this tooth from the small two-fanged second pre- 
molar, the first premolar having entirely disappeared. The third and fourth 
premolars have a broad, swollen, anterior transverse crest, and somewhat nar- 
rower and much more slender posterior crests. The fourth premolar has a 
faintly developed combing crest, as in the third premolar of Amynodon. The 
molars show a sudden and remarkable increase in size, occupying a space three 
times as great as that taken by the premolars. The crown of the first molar is 
transversely oblong, measuring 23 by 2 inches ; the second is subquadrate; 
the third is antero-posteriorly oblong. As in the premolars, the anterior crest 
in m! and m? is the largest, and without distinct “anti-crochet,” but the pos- 
