PLATE CI 



Dentition of Type Skull of Brontops robustus 



Plate prepared under the direction of Professor Marsh. One-half natural size. (See p. 495.) 



Yale Mus. 12048, Dry Creek, 5 miles northeast of Chadron, Nebr. (J. B. Hatcher), Chadron formation, probably upper levels. 

 The upper teeth (Bi, B2) may be compared with those of B. dispar (PI. LXXXVIII). In B. robustus the internal cingula of 

 the premolars are somewhat reduced, but the postero-internal cusps or tetartocones are better developed. There is also 

 a wide postcanine diastema. Although the canines suggest those of Broniotherium (PL CLXIII) the incisors are not broadly 

 cingulate posteriorly, as in that genus; the tetartocones, especially in p^, are more retarded; p^ is also less molariform than in 

 Broniotherium; and all the cheek teeth are narrower transversely. The lower teeth (Aj, Aj) show reduced external cingula 

 on the premolars and molars. 



