PLATE CLXVI 



Type and Referred Specimens of Brontotherixjm hypoceras 

 (See p. 562) 



A, Horn, type of Brontolherium hypoceras (Am. Mus. 6361), northeastern Colorado, Chadron formation. Natural size. Of the 

 type of this species several skull fragments are all that remain; among these is the tip of the right horn, here shown in the 

 front (A'), back (A-), and top (A') views. The horn has a compressed oval section, as in brontotheres, but is very small. 



B', SkuU referred to Brontoiherium hypoceras?, neotj'pe (Nat. Mus. 4273), skuU 1, Indian Draw, Big Badlands, S. Dak., Titanolherium 

 zone, probably level upper A (Hatcher). One-third natural size. The horn tip closely resembles that of the type of B. 

 hypoceras. B-, The same. Upper front teeth, natural size. The dental measurements are about the same as in B. leidyi, 

 and this may represent a more progressive mutation from that species. The extreme forward position of the horns is empha- 

 sized by crushing. The massive swollen canines and large incisor are of Brontolherium type. The inner incisors have probably 

 dropped out as the animal grew old. 



C, Horn and nasal referred to Brontotherium hypoceras (Nat. Mus. 4940), skull m, Indian Draw, Big Badlands, S. Dak., Titano- 

 lherium zone, level upper A (Hatcher). One-third natural size. This specimen is referred to B. hypoceras on account of the 

 similarity in the horn and nasals. 



