86 EIIINOCEROS. 



posterior three molars, and on the outer side of the posterior lobe of the same teeth, 

 except the last. Between the bases of the lobes externally it forms a small 

 tubercle. 



Other Teeth. — No incisors are preserved in any of the specimens, but from a 



portion of alveolus preserved in one of the latter, already referred to, it is of course 

 conclusive that incisors existed in the adult, at least in the uj^per jaw. 



MEASUREMENTS OF THE HEAD AND TEETH. 



Lines. Inches. 



Length of pkull from the upper margin of the occipital foramen to the inter- 

 maxillary bone ........... IG 9 



Length of skull from same position to the first molar ..... 15 4 



Breadth of inion at the mastoid processes; estimated ..... 5 



Greatest breadth at the zygomata ........ 8 



From the tip of one post-glenoid tubercle to the other; estimated ... 3 6 



Distance from the meatus auditorius externus to the lachrymal tubercle . . 8 



Height of face from alveolar margin on a lino with the anterior orbital margin 5 6 



Height of face from alveolar margin on a line with the infra-orbitar foramen . 4 6 



Greatest breadth of forehead at the supra-orbitar processes .... 7 



Length of upper molar series ......... 7 3 



Greatest breadth of seventh molar ........ 1 7 



Greatest breadth of sixth molar ......... 1 8 



Greatest breadth of fifth molar ......... 1 7 



Greatest breadth of fourth molar ........ 1 6 



Greatest breadth of third molar ......... 1 4 



Greatest breadth of second molar ........ 1 



Greatest breadth of first molar ......... 9 



Antero-posterior diameter of last lower molar ...... 1 6 



Antero-posterior diameter of the third lower molar ..... 1 1 



Rhinoceros IVebrascensis, Leidt. 



(Pl.ite XIV., XV.) 



RMiioceros Nelrascensis, Leidy : Proc. Acad. Nat. Sci., 1850, v., 121; Owen's Rep. of a Geol. Surv. of 

 Wise, etc., 556. 



Aceratherium Nebrascensis, Leidy: Proc. Acad. Nat. Sci., 1851, v., 331. 



Of the smaller Rhinoceros of Nebraska we possess portions of at least twelve 

 different individuals, as follows : — 



1. The anterior portion of a skull, accompanied by the lower jaw, of an adult 

 individual. The former has the forehead, orbital entrance, and molar teeth well 

 preserved, but the face is very much broken, and its nasal part is displaced. The 

 lower jaw contains all the molars in perfect condition, but it has lost its rami and 

 the symphysis. (XIV. 1-3.) From Captain Stewart Van Vliet's collection. 



2. A much mutilated face, containing on both sides the molar teeth nearly per- 

 fect. It belonged to a nearly adult individual, as the teeth, which belong to the 

 permanent series, are all in place except the last, which has about two-thirds 

 protruded. (XIV. 13.) From the collection of Dr. Owen. 



3. The skull, accompanied by a small fragment of the lower jaw, of a very old 

 individual. The former has its upper part broken away, but the base is nearly 



