U. S. GEOLOGICAL SURVEY 



MONOGRAPH 55 PLATE XXI 



A, Brontops hrachycephalu 



LEFT UPPER PREMOLARS OF OUGOCENE TITANOTHERES 



male (Nat. Mus. 4258). B, AUops walcotti, male, type (Nat. Mus. 4250). 

 leidyi, type (Nat. Mus. 4248). All natural sise 



C, Hrontotherium 



