526 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



crowns are at present broken away but could not 

 have projected much above the level of the other 

 teeth. There is absolutely no space for the first 

 premolar; the second is placed directly behind the 

 canine and has an elevated anterior, noncrescentic 

 lobe and a posterior crescent; the third and fourth 

 premolars exhibit both anterior and posterior cres- 



Menodus proutii (Leidy) 



{Titanotherium proutii Leidy, 1852) 



Plates LXXXII, CXXV, CXXVI; text figures 160, 409, 438 



(For original description and type references see p. 205] 



Geologic Tiorizon. — Precise geologic level unknown, 

 probably middle level of the Titanotherium zone, 

 Chadron A 3 or B 1. 



Figure 436. — Skull of Menodus heloceras 

 , Side view; As, top view; Aj, palatal view. One-sixth natural size. Am. Mus. 14576; found at the very base of the Titanotherium 

 zone immediately overlying beds probably equivalent to Uinta C, Beaver Divide, near Hailey, Wyo. This very primitive skull 

 agrees with the type of Menodus heloceras in the trihedral basal horn section, elongate proportions, and slender zygomata. It is 

 also structurally allied to Allops walcotti and Brontops brackycephalus. The upper molars, though poorly preserved, resemble those 

 of Brontops brackycephalus rather than those of Menodus proutii. 



cents, no internal cingula, faint external cingula. The 

 vertical arching of the premolar series is very pro- 

 nounced. The molars also are devoid of internal 

 cingula but present more or less complete external 

 cingula. 



Specific cJiaracters. — Size of type jaw slightly 

 smaller (mi-nis 234 mm.) than that of jaws referred to 

 M. trigonoceras. Referred upper teeth (p'-m^ 313 

 mm.) also smaller than in M. trigonoceras. Upper 

 and lower premolar-molar series with cingula. 



