TRANSACTIONS OF WAGNER 

 4 2 



RHINOCEROS 



or absence of this portion of the tooth would seem in itself a character of 

 comparatively little value.* 



The inner, pinched-up, basal portions of the protoloph and metaloph, the 

 foreshadowing of the pillar, are slightly narrower in proterus than in fossiger, 

 and the cingulum is usually better developed on pm. 3 and 4. As a rule, too, 

 the crests approach each other more closely in the Florida specimens than 

 they do in fossiger, so that the pits produced by the wear of the teeth appear 

 earlier and endure longer. This is best seen in the third upper molar of 

 fossiger, which has a comparatively large anterior fossette, but the character is 

 not constant, and different teeth vary much. In one specimen of fossiger in 

 particular, plate viii. fig. 14, the fossette is abnormally large, there is a rudimen- 

 tary crista, and the metaloph is directed backward as in the first and second 

 molars. 



The following table gives the measurements of the molar teeth of protcrus 

 and fossiger, the first row of figures giving the antero-posterior diameter, the 

 second row the transverse : 



The antero-posterior measurement depends greatly on the amount of 

 wear which the tooth has undergone and also on the curvature of the tooth, a 

 little more curve adding materially to the measurement. The measurements 

 given above are all taken in a straight line along the widest portions of the 

 teeth. The measurements of teeth of Aphelops fossiger are of interest, as the 

 skulls represent individuals of very different ages. In 1350 the third molar 

 is exposed for a height of .30 mm., in 1349 it is fully through but unworn, in 



*In the American Naturalist for March, 1894, page 241, Mr. Hatcher describes the dentition of 

 a specimen of Aphelops fossiger, suggesting that it may prove to be a new species, but unless other 

 specimens exactly similar should be found, I should consider it merely a case of individual variation. 

 Furthermore, the numerous specimens examined show that the crista and crochet are by no means 

 constant in their development, and that too much stress should not be laid on them as characters. 



