DAKOTA AND NEBRASKA. 221 



The temporal fossa is proportionately longer, but of less depth than in the Indian 

 Rhinoceros. Anteriorly it is better defined from the orbit, from the greater promi- 

 nence outwardly of the supra-orbital boundary and of the ridges converging to the 

 latter from the sagittal ci'est and from the vicinity of the spheno-orbital foramen. 

 Behind, it extends upon a wide everted border separating it from the inion. 



The temporal fosste are separated from each other at the upper back part of the 

 cranium by a short thick sagittal crest, which is longitudinally grooved and early 

 ■ divided into the temporal ridges. These are long and prominent, and diverge at a 

 very acute angle in a curvilinear manner. 



The temporal surface inclines more than in the Indian Rhinoceros, both at the side 

 of the cranium and upon the root of the zygoma. The latter springs from near the 

 middle of the lower part of the temporal region. 



The side of the face forms a nearly vertical plane sloping inwardly and forward, 

 and is rather abruptly defined from the upper part. In front of the orbit it is of 

 greater width fore and aft proportionately than in the Indian Rhinoceros. 



The orbit is less advanced in position relatively than in the latter, its anterior 

 margin corresponding in position with the interval of the fifth and sixth molars. The 

 orbital entrance forms about three-fourths of a circle, with a diameter of about two 

 inches and a quarter. Its plane is nearly vertical, but has a feeble inclination down- 

 ward and a slightly stronger one forward. It is bounded above by a thick, convex, 

 roughened supi'a-orbital prominence forming part of the lateral boundary of the 

 forehead. The floor of the orbit is more deeply excavated, and the roof is more 

 extensive proportionately than in the Indian Rhinoceros. 



The facial surface of the lachrymal is about as large proportionately as in the 

 latter, and is somewhat depressed beneath the extension forward of the supra-orbital 

 prominence. At the orbital margin it is produced in a roughened process, within 

 which there appear to be two lachrymal foramina, one above the other. 



The naso-maxillary suture descends obliquely for two and a quarter inches, and at 

 its lower part is not more than the fourth of an inch distant from the upper end of the 

 premaxillary bone. The latter extends higher than in the Indian Rhinoceros, and is 

 connected with the contiguous maxillary bone by a strong serrated suture. 



The infra-orbital foramen is situated about an inch and a half above the interval 

 of the second and third molar teeth. 



The forehead and upper fore part of the face together form a long, lozenge-shaped, 

 nearly horizontal plane. The forehead extends backward in a long somewhat acumi- 

 nate triangle between the temporal ridges, and appears depressed from the prominence 

 of the latter. Where the temporal ridges at their fore part begin to turn downward 

 they lose their upward prominence, and the forehead intermediately appears nearly 

 level. On each side it forms the supra-orbital prominences before mentioned, which 



