Marsh Collection, Peabody Museum. 213 



The element of uncertainty comes in the determination of 

 the nature of the first two teeth, and I can find no proof that the 

 single pointed tooth is the canine, as held by Cope and Osborn. 

 There is certainly no indication of the maxillo-premaxillary 

 suture to be found, and the tooth in question may quite as well 

 be a premolar as a canine. In fact, in the fragmentary maxilla 

 of the other specimen (No. 41) there is evidence of a tooth 

 with more than a single root in advance of the two premolars, 

 and if the two specimens belong to the same species, which is 

 more than likely, there were certainly three premolars in 

 the upper jaw. In like manner I am unable to discover any 

 conclusive evidence in favor of Osborn's statement that there 

 are three premolars in the lower jaw, together with a canine 

 and two incisors. I am strongly inclined to believe that 

 there were three premolars in the lower jaw, however, and that 

 Osborn's determination is correct ; but at the same time the 

 specimens are not sufficiently perfect to furnish conclusive 

 proof of the fact. Nor can it be demonstrated at the present 

 time that the Big Horn and the Bridger species belong to the 

 same genus. Upon general considerations, I think it most 

 unlikely. I believe, moreover, that the Big Horn species is a 

 type with three premolars above and below, and that it is gen- 

 erically distinct from the Bridger Anaptomorphus. I have 

 refrained from proposing a new genus for this species, prefer- 

 ring to let the matter rest until the dentition of both the Big 

 Horn and the Bridger forms is more fully known. 



In the matter of the restoration of the skull, I can find no 

 warrant for the extremely abbreviated face which Osborn gives 

 in his drawing. The contour of the muzzle was undoubtedly 

 much more like that of Tarsius, with which the cranial anat- 

 omy so closely agrees. Apparently very little consideration 

 has been given to these resemblances between Tarsius and the 

 Big Horn fossil, which Cope pointed out. It will perhaps be 

 well to recall them here, with some emendations and additions. 

 They are as follows : (1) The species are of about the same 

 size, both being small ; (2) the brain development is relatively 

 large ; (3) the brain projects well backward beyond the fora- 

 men magnum, so as to overhang the occiput ; (4) there is no 

 sagittal crest ; (5) the face is considerably shortened, and the 

 orbits are large ; (6) the canal for the internal carotid pierces 

 the petro-tympanic ; (7) the dentition is very probably the same, 

 with the exception of the loss of one pair of incisors in the 

 lower jaw in Tarsius / (8) the structure of the molars and pre- 

 molars is very similar ; (9) the bullae are much inflated, and the 

 external wings of the pterygoids extend backward, so as par- 

 tially to enclose the bullae externally ; (10) the lachrymal 

 extends out upon the face, and the opening of the lachrymal 



