PLATE CXXIII 



Type Skull of Menodus heloceeas 



A', Palatal view; A^, top view; A^, lateral view, left side; A^, posterior view. One-fourth natural size. (See p. 524.) 

 Am. Mus. 6360, type. Horsetail Creek, northeastern Colorado, Chadron formation. This very imperfect type skull e.xhibits well 

 the most primitive known stage in the generic characters of Menodus, such as the length and slenderness, the unexpanded 

 zygomata, and the narrow parietal crest. The horns also, although in an early phylogenetic stage, are trihedral in basal 

 section, as in Menodus trigonoceras, from which the nasal region is restored. The palate is unnaturally widened by crushing. 

 The teeth so far as preserved present nothing noteworthy. The basicranial region is elongate. 



