PLATE CLXXXIII 



Skull of Brontotherium curtum and Horn of Brontotherium hypoceras 

 Plate prepared under the direction of Professor Cope. (See pp. 212, 562, also Pis. CLXVI and CLXXXV) 



A, Skull referred to Brontotherium curtum (Am. Mus. 6346), cotype of Symborodon hucco Cope, Horsetail Creek, northeastern Colo- 

 rado, Chadron formation. One-third natural size. This is one of the specimens upon which Cope founded his species 

 Symborodon bucco, but it was not the leading specimen of the original description, and it appears to be generically distinct 

 from the lectotype of that species. (See p. 212 and PI. CLV.) The reference to Brontotherium curtum is based especially 

 upon the similarity in the zygomatic arches and cranial vertex. 



Bi, B2, B3, Fragment of horn, part of type of Brontotherium hypoceras (Cope) (Am. Mus. 6361), northeastern Colorado, Chadron 

 formation. (Compare PI. CLXVI.) 



