362 Wo7'tman — Sticdies of Eocene Mammalia in the 



The type specimen was found by Professor Marsh, at 

 Henry's Fork of Green Kiver, August 9, 1873. The other 

 specimens were obtained at the same locality. 



In addition to the species herein described, there are prob- 

 ably at least two otliers indicated by fragmentary specimens. 

 One of these consists of an upper molar tooth of a small 

 species about equal in size to M. elegans. It comes from the 

 upper horizon of Henry's Fork, and differs from the upper 

 teeth which I have attributed to M. elegans in the absence of 

 the mesostyle, absence of intermediates, and the greater promi- 

 nence of tlie postero-internal cusp. It apparently belongs to 

 Microsyops^ but I refrain from proposing a specific name for 

 so fragmentary a specimen. 



In like manner, there is a fragment of an upper jaw con- 

 taining two molars, from the lower horizon. The structure of 

 these molars differs from all other species of Microsyops from 

 the Bridger beds in the more distinctly conical shape of the 

 external cusps, as well as in the prominence of the intermedi- 

 ates. I suspect that the form may be the same as one of the 

 Wind River species in which the upper teeth are entirely 

 unknown. 



Smilodectes gen. no v. 



This genus is founded upon the specimen originally described 

 by Professor Marsh under the name of Hyojpsochts gracilis. 

 Osborn in his synonymy refers it to Sarcolemur, but the struc- 

 ture of the teeth distinctly forbids its reference to either of 

 these genera. In certain respects the dentition, as far as 

 known, resembles that of Microsyops more than that of any 

 other genus, but in others it exhibits distinct relationship to 

 that of Notharctxis and Limnotherium. The number of teeth 

 in the lower jaw is eight, as against seven in Microsyops^ of 

 which the most anterior is an enlarged incisor. Just as in 

 Microsyops^ the succeeding tooth may be rated either as a 

 canine or an incisor; if a canine, there are then three pre- 

 molars and if a premolar, there are four. The fourth premolar 

 is not molariform. The single enlarged incisor distinguishes 

 the genus from N^othctrctus and Limnotherium^ and the more 

 complex fourth premolar from M.ixodectes. 



Smilodectes gracilis Marsh. 

 Hyopsodus gracilis Marsh, tliis Journal, July, 1871, p. 42, 



The type of this species and genus consists of the anterior 

 part of a left mandibular ramus, figure 118, containing the 

 fourth premolar, first molar, and a portion of the third pre- 



