PLATE CXXXV 



Skulls of Menodus trigonoceras? and Menodus giganteus 

 One-fourth natural size. (See pp. 523, 528, 531) 



A, Skull of female Menodus trigonoceras? (Am. Mus. 1067), Hat Creek Badlands, Nebr., Chadron formation. Front view of dis- 



torted skuU with associated lower jaw. This specimen is smaller than the supposed female of M. giganteus (B), but it is a 

 little larger than the cotype of M. trigonoceras. It may be a female of M. varians, which it somewhat resembles in the right 

 horn. The incisive borders were apparently edentulous. The slender canines are cingulate. The thick horns are trihedral 

 in basal section, the left horn badly distorted. The nasals are wide distaUy, with two small processes on each side of a median 

 notch. These processes with the whole rugose end of the nasals probably served for the attachment of a powerful levator 

 labii superioris muscle. The buccal swellings of the zygomata are small. 



B, Skull of female of M. giganteus (Am. Mus. 506), Big Badlands, Cheyenne River, S. Dak., Chadron formation. This skull illus- 



trates well the effect of lateral crushing. Slender proportions are shown by the horns, canines, and zygomata. In dental 

 measurements this skull is somewhat inferior to those in the males of M. ingens. 



