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4"? 



RHINOCEROS 



1348 the third molar is in use, while 1347 is a very old animal in which the 

 teeth are worn down nearly to the roots. As indicated by this series, there is 

 a gradual decrease in length and increase in width of the third molar. The 

 premolars and molars are well shown on plate viii. 



The number of lower teeth in the collection is much less than that of 

 the upper grinders, and they do not appear to have been so consociated with 

 these as to render it possible to state to which of the two species under con- 

 sideration they belonged. Those shown in plate x. figs, i, 2, 8, 9, and 10, 

 probably from their size, belong to A. protcnis, and well represent the change 

 in appearance brought about by wear. 



The only well-preserved portion of the vertebral column is an axis, lack- 

 ing the posterior epiphysis, but a few other more or less imperfect cervicals 

 are also present. The general character of this axis, like that of fossiger, is 

 stout and rugose. The articular surface of this and one other axis is continu- 

 ous from side to side ; in a third specimen there is a narrow interval between 

 the articular surface of the odontoid and of the lateral facets. 



Measurements are as follows : 



Proterus. Fossige . 



Width across articular facets . .147 mm. . 147 mm. 



Depth of articular facets . . .36 " .45mm. .42 " 



\Vidthacrosspostzygapophyses . .86 " .86 " .112 " 



Diameter of neural canal . . .36 " .34 " .39 " 



SCAPULA. The glenoid portion is all that is present of the scapula, and 

 there is nothing to distinguish it from the corresponding portion of the scapula 

 of fossiger. The glenoid fossa measures .80 mm. long and .60 mm. wide. 



HUMERUS. The only humerus approaching completeness, plate xiv. fig. 6, 

 lacks the tuberosities. It is somewhat slender, and the deltoid ridge is not- so 

 pronounced as in a corresponding bone of fossiger, but the burner! of both are 

 remarkable for the great and abrupt projection of the epicondyle. 



Proterus. Fossiger. 



Length between articulations . . .305 mm. .308 mm. 



Width across epicondyle . . . .127 " .138 " 



ULNA. The ulna is represented by one complete specimen, -plate xiv. fig. 

 5, the olecranal portion of another, and the distal extremities of three. Two 

 of these last are much larger and more massive than the other, and consider- 

 ably exceed in size the specimen figured. 



