220 ON THE EXTINCT MAMMALIA OF 



Rhinoceros crassus, is indicated by a few remains discovered by Dr. Hayden on the 

 L'eau-qui-court, or Niobrara River, Nebraska. It is of pliocene age, and belongs to 

 bed F of Dr. Hayden's sections. 



A fourth species, named Rhinoceros meridianus, is indicated by the fragment of a 

 tooth obtained from a tertiary deposit of Washington county, Texas, and submitted 

 to the author for examination by Dr. B. F. Shumard. 



The remaining species, named Rhinoceros hespeidus, is indicated by portions of a 

 lower jaw from Calaveras county, California, submitted to ray inspection by Professor 

 J. D. Whitney. 



RHINOCEROS. 



Rhinoceros occidentalis. 



The species to which the above name has been appropriated has been previously 

 described in Dr. D. D. Owen's Geological Report of Wisconsin, &c., and subsequently 

 more fully in the Ancient Fauna of Nebraska, and is represented in plates xii and 

 xiii of that work. 



The species was between a half and three-fourths the size of the living Indian 

 Rhinoceros, and is indicated by a comparative abundance of remains. The collection 

 of every explorer of the Mauvaises Terres submitted to my inspection contains speci- 

 mens consisting of much mutilated skulls, fragments of others, portions of jaws with 

 teeth, isolated teeth, and bones of other parts of the skeleton. The greater portions 

 of three skulls, as far as their anatomical characters can be compared, agree with one 

 another in size, proportions, and details of form, as much as usual among the different 

 individuals of a species. 



The best specimen of the skull of R. occidentalis I have had the opportunity of 

 examining is that from the collection of Dr. Owen, already described in the Ancient 

 Fauna of Nebraska, and represented in plate xii, and figure 1, plate xiii, of that work, 

 and reproduced in plate XXII of the present work. It is an adult specimen, and is 

 nearly three-fourths the size of that of the Indian Rhinoceros. It is unaccompanied 

 by the lower jaw, and has lost a great portion of the right side and the end of the 

 snout. To make up for the loss of the lower jaw, I have the opportunity of examin- 

 ing one containing a full series of teeth, in the collection of Prof. James Hall, besides 

 several other specimens containing the molar teeth. 



Side view of the shall. — In outline, the side view of the skull, plate XXII, figure 2, 

 of R. occidentalis, presents the form of an irregular transversely oblong square, 

 pointed at the fore part. In comparison with the skull of the Indian Rhinoceros it 

 appears as if it had the two extremities pressed above from each other so as to be 

 rendered nearly horizontal the greater part of its length. 



