PLATE LXXXIII 



Skull of Brontops brachycephalus 

 Plate prepared under the direction of Professor Marsli. One-fourth natural size. (See p. 4S4 and PI. LXXXVII) 



Nat. Mus. 4947, skull B, paratype, female; Big Badlands, S. Dak., "west side of Quinn Draw, near the Cheyenne River" (J. B, 

 Hatcher); Tiianotherium zone ( = Chadron formation) of South Dakota, level lower A (Hatcher). Ai, Top view; A2, side view; 

 A3, front view. The female sex is inferred from the small horns, slender zygomata, less brachycephalio proportions, and weak 

 canines. The horns are smaller and more primitive than in any other known Oligooene titanothere; the skull comes from an- 

 extremely low level in the "Titanoiherium beds" (14.4 feet above the Pierre shale and 130.6 feet below the top of the "Tiiano- 

 therium beds," according to Hatcher) and seems to represent a slightly more primitive stage than the type of the species. 



