902.] 



Osborn, Olis^ocene Titanotheres. 



97 



Genus MEGACEROPS Leidy. 



This genus may have taken origin in the broad-skulled 

 Limnohyops manteoceras or Palcsosyops paliidosus of the 

 Eocene, although no horned type of the latter is known. It 

 is known from the imperfect type of M. coloradensis and a 

 very rich variety of species from the Lower, Middle, and 

 Upper Beds, which have previously been referred to other 

 genera. In the typical members the horns are slightly diver- 

 gent and retroverted. There is a wide variation in progres- 

 sive character between such species as M. brachycephalus 

 and dispar, M. bicornutus, M. selwynianus, M. tichoceras, M. 

 robustus, but it is found that the variations of age, growth, 

 and sex, especially in species such as M. dispar and M. 

 robustus, bridge over the differences between the types of 

 said species and present intermediate forms. Furthermore 

 these species are much more closely united to the general type 

 of Megacerops than to any other genus. 



LOWER BEDS. 



Megacerops brachycephalus, sp. nov. 



The type of this species is No. 4261, U. S. Nat. Mus. It in- 

 cludes very small, broad-skulled Titanotheres with very rudi- 

 mentary sec- 

 ond internal 

 cones upon 

 the upper 

 premolars ; 

 nasals elong- 

 ate, narrow- 

 ing anteri- 

 orly, as in 

 PalcBosyops. 

 Horns of an- 

 teroposterior 



oval section placed above orbits. It is represented in the 

 National Museum by numerous skulls besides the type, all 



\^Febrtwry, igo2.'\ 7 



Fig. 3. Megacerops brachycephalus 

 Sk. F.) Not the type. X i. 



(U. S. Nat. Mus. No. 4258, 



