162 BULLETIN OF THE 
3. M. dolichoceras. 
M. coloradensis. 
-Ficure 6.— The same skulls viewed from above, showing the nasals and horns, and sections of the bases of the horns. 
ls 2. M. tichoceras. 
Fieure 5. — Skulls of three species of Menodus in front view, showing the variations in the horns, nasals, and anterior nares. 
The accompanying figures show the four types of skull as seen in the fronto- 
nasal region. The first type, with long nasals and short erect horns, is repre- 
sented by M. coloradensis and characterizes also M. ingens and M. angustigenis. 
The second type, with medium nasals and short obliquely placed horns, is 
