University of California Publications. [Geology 



of all of the fragments seen, the horns did not taper rapidly, and 

 tended to be considerably elongated. 



The surface of the horn core is comparatively smooth, with 

 almost no pits or roughnesses. The texture is solid, and not 

 spongy as in the true bovine forms. On none of the specimens does 

 there appear to be a distinct line marking the proximal edge of a 

 horny sheath. 



In specimen no. 1189-1 (fig. 5), representing an individual 

 considerably smaller than the type, there is a single strong, 

 acute crest developed, which corresponds to ridge a of the type. 

 The general form of the horn is like that of Ilingoceros, and it 

 may be referred tentatively to I. alexandrae. 



In specimen no. 11892 (fig. 2) a horn considerably smaller 

 than the type shows near its base a narrow, sharp ridge with a 

 high, rounded one accompanying it on one side, and a lower one 

 on the other side. The lower accompanying ridge dies out above 

 or unites with the middle one leaving only two prominent ones. 

 ►Some distance above the base the sharper one becomes less 

 abrupt and more like the other. The sharp median ridge, called 

 ridge b (fig. 2), may correspond to a minor crest that arises 

 from the posterior angle of the postorbital process of the frontal 

 in the type of /. alexandrae. The principal spiral ridge arising 

 above the orbit in the type specimen may be called ridge a (see 

 figs. 1 and 4). It probably corresponds to the ridge to the right 

 of the median elevation shown in fig. 2. The posterior elevation, 

 ridge e, on no. 11892 possibly corresponds to the most posterior 

 elevation arising behind the postorbital process in the type. 



Another specimen, no. 11899, seems to be quite certainly of 

 the same type as no. 11892. It belongs to an individual of larger 

 size than no. 11892, but is smaller than the type. These speci- 

 mens may both represent an earlier stage of development of this 

 species than the type specimen. The fragment, specimen no. 

 11899, is also probably from a part of the horn core somewhat 

 farther above the base than the uppermost part of the horn 

 core as represented in the type. They may both be referred 

 tentatively to this genus as form B, in contrast with the typical 

 form represented in specimen no. 11880 (figs. 1 and 1). 



