204 Troxell — DiceratJierium and the Diceratheres. 



Dicer atherium cuspidatum, sp. nov. 



(Fig. 7.) 



Holotype, Cat. No. 12007, Y. P. M. Middle John Day, near Bridge Creek, 

 John Day Valley, Oregon. 



The holotype of this new species consists of both 

 maxillaries with all the cheek teeth save P^ As com- 

 pared with D. armatum, the smaller specimens seem 

 generally to be more progressive in the development 

 of enamel folds on the teeth, and this new species, espe- 

 cially, shows the complex pattern crennlations, together 

 with additional cnsps and irregularities of the cingulum 

 to an unusual degree. 



Fig. 7. 



Fig. 7. — Diceratherium cuspidaium, sp. nov. Holotype. Cat. No. 12007, 

 Y, P. M. P^ is missing. The teeth have many folds of the enamel and 

 there are strong internal basal cusps. X l/^* 



The species name is chosen because of the small conical 

 tubercles arising from the floor of the median valley in 

 the first and third molars, which in M^ come to be high 

 cusps 6 or 7 mm. tall and 4 mm. broad at the base, a 

 feature unique in the rhinoceroses. Except for this 

 internal cusp and a short segment of the cingulum, the 

 valleys of the molars are open; they are not obstructed 

 by the crochet and antecrochet as in D. lohatum and the 

 slender protocones are not set off by distinct grooves 

 from the antecrochet. 



A conspicuous style marks the outer end of the poste- 

 rior cingulum on M^, but with the exception of M^ neither 

 molars nor premolars have a trace of cingulum on the 

 outer side. 



The size is approximately that of D. annectens {fig. 3), 

 but a marked difference is shown on the premolars by 

 the cristae and crochets, the cingulum encircling the deute- 



