U. S. GEOLOGICAL SURVEY 



MONOGRAPH 55 PLATE XX 



UPPER AND LOWER CANINES OF OLIGOCENE TITANOTHERES 



A, Brontotherium gigas, supposed female (Am. Mus. 1006), right superior canine, external view. B, Bro>itothe>-iu7rt Sigas^ male (Am. Mus. 492), 

 right superior canine, external view. C^, Brontotherium leidyi (Carnegie Mus. 93), right superior canine, external view^; C^ the same, 

 left upper canine, internal view. D, Brontops robuiiws, male (Am. Mus. 1083), right superior canine, external view. £>, Menodus giganteus, 

 male (Am. Mus. 505), right superior canine, external view; E^, the same, left superior canine, internal view. F, Allops walcottit type (Nat. 

 Mus. 4260), right inferior canine, external view. G, Menodus heloceras (Carnegie Mus.), right superior canine, external view. H, Bronto^ 

 therium medium. (Am. Mus. 1051), right inferior canine, external ^/ie.vv. Ii, Brontotherium. leidyi (Am. Mus. 516), right inferior canine, 

 external view; I^, the same, left inferior canine, internal view. Ji, Menodus trigonoceras (Nat. Mus. 4745), left infe;-ior canine, external 

 view; J^, the sam.e, right inferior canine, internal view. All natural siz;e 



