No. 2.] THE RELATIONS OF PROTOCERAS. 323 



but on the parietals, immediately behind the frontal suture. 

 . . . The horn-cores are well separated from each other, and 

 point upward, outward and backward, overhanging somewhat 

 the temporal fossae. They are conical in form, with obtuse 

 summits" (No. 5, p. 81). Osborn and Wortman, who have 

 compared the type with their own specimens, report that these 

 parietal "horn-cores" are about equal in size to the anterior 

 frontal protuberances of the male skull figured by them, and 

 are therefore very much smaller than the parietal protuber- 

 ances of that animal and of quite a different shape. In 

 Marsh's specimen, so far as can be judged from the figure (No. 

 6, PI. XXII, Fig. i), the median frontal eminence would 

 appear to be more prominent than in the females which have 

 been described above and the maxillary fossa is of a different 

 shape and more distinctly bounded behind. The thinness of 

 the maxillaries precludes the supposition that there can have 

 been any great protuberances upon those bones. 



Osborn and Wortman conclude that the type specimen was 

 the skull of a female, and this result is altogether probable. 

 At the same time, however, it is remarkable that among the 

 numerous undoubted female skulls which have been collected, 

 not one should show the conical, horn-like protuberances on 

 the parietals which characterize the type. More extensive 

 material will be required to determine the significance of this 

 feature. It may be only an individual variation, in which the 

 female has approximated the characters of the other sex, as we 

 have already seen to occur sometimes in the case of the maxil- 

 lary protuberances. Or, in the second place, the type speci- 

 men may represent the female of a species distinct from that 

 to which the individuals described in this paper belong. I 

 was at one time tempted to believe that the type might be 

 the male of a more ancient genus than the specimens which 

 Osborn and Wortman referred to Protoceras, and that it would 

 be found to have come from the Oreodou beds. Mr. Hatcher 

 has, however, lately visited the spot whence the type was 

 taken, and writes me that it is in the Protoceras beds, well up 

 toward the top. 



