U. S. GEOLOGICAL SURVEY 



MONOGRAPH 55 PLATE CXVUI 



SKULL OF ALLOPS SEROTINUS 



(See p. 517, also PL 



Am. Mus. 520, Cheyenne River Badlands, S. Dak., Chadron formation. One-fourth natural f 



CXVn.) A skull referred to Allops serotinus. The generic chara(5ters of Allops which are seen in this view are as 

 follows: Incisors 2-1, canines compressed anteropo^eriorly, premolars with sharp external and internal cingula, 

 grinding teeth and skull of moderate breadth, zygomatic expansion moderate, horns ^videly divergent. The reference 

 of this specimen to A. serotinus is based especially on the detailed resemblances in the premolars to those of the referred 

 skull Nat. Mus. 4938 (PL CXX, B). The poitero-internal cusps of the premolars are less developed than in A. 



