MUSEUM OF COMPARATIVE ZOOLOGY. 167 



skull with the greatest cliaineter 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 

 poTverful 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 i?, 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 1^ inches in transverse diameter. It is 

 followed by a diastema of two inches. 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 maxillary 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 incisors 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 decrea.sed 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 entirelj^ disappeared. The tliird 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 2| by 2 inches ; the second is subquadrate; 

 the third is antero-posteriorly oblong. As in the premolars, the anterior crest 

 in ml and m^ is the largest, and without distinct " anti-crochet," but the pos- 



