DAKOTA AND NEBRASKA. 



227 







Lines. 



Lines. 



Lines. 



Breadth of second lower molar, 



. 11 



lOi 



13 



Breadth of third 



a 



. Hi 



12 



14 



Breadth of fourth 



a 



. 12 



12J 



15i 



Breadth of fifth 



ti 



. 14J 



15J 



18 



Breadth of sixth 



u 



• • 



. 16J 



lU 



18 



From the measurements given of the lower jaws with their teeth, it will be 

 observed that they are quite disproportionate in compai'ing the size of the teeth with 

 the depth of the bones. The differences are to a great extent due to a difference in 

 age. Thus the first two specimens belonged to individuals of nearly the same age. 

 The teeth are much worn away, and the fore and aft measurements considerably 

 reduced from their more juvenile condition, due to their closer approximation and the 

 disappearance of the intervening enamel. In the second specimen the jaw is rendered 

 deeper than the others, from the higher extension of the alveolar processes inter- 

 vening between the fangs of the teeth. In the third specimen the teeth are com- 

 paratively little worn, well separated, and have the intervening enamel nearly of its 

 original thickness. 



Of other bones of Rhinoceros occidentalis the different Mauvaises Terres collections 

 contain many fragments, chiefly of the larger bones of the extremities. They repeat 

 the form of the corresponding bones of the living Rhinoceroses. 



The collection of Dr. Hayden contains an entire humerus, together with the radius 

 and ulna, imbedded in a mass of matrix, apparently referable to R. occidentalis. The 

 measurements of the bones are as follow : 



Inches. 



Length of the humerus, ... . . . . . 12i 



Breadth of proximal end, fore arid aft, . . . . . 5i 



Breadth of proximal end, transversely, 

 Diameter of head, fore and aft. 

 Breadth of distal end, 

 Breadth of ante-brachial articulation, 

 Length of fore-arm from head of radius, 

 Breadth of distal end of fore-arm. 

 Breadth of middle of fore-arm. 



Several proximal ends of femurs considered to bel 

 following measurements : breadth of femur transvert 

 chanters, five inches; width of trochanters fore and aft, three and a half inches; 

 diameter of head transversely, two and a quarter inches. 



A specimen of the distal end of a femur has the following moasuroraents : breadth 



2h 

 3i 

 2 

 lOJ 

 3 

 2i 



ong to the same species have the 

 sely, including the head and tro- 



