V. NEW VERTEBRATES FROM THE MONTANA TERTIARY. 

 By Earl Douglass. 



During the summer of 1902 explorations were continued by the 

 writer in western Montana for the Carnegie Museum. Collections of 

 rock samples, and of fossil plants, invertebrates, and vertebrates were 

 obtained from the Oligocene and Miocene formations. Special effort 

 was made to discover the conditions under which the various deposits 

 were formed. While it will require much work and careful study to 

 interpret the history of Tertiary times in this region, it is nevertheless 

 important to record such data as tend to elucidate the problem. In 

 this preliminary sketch the writer wishes to give only a few of the lead- 

 ing facts, leaving a more thorough discussion of the matter to a time 

 when more extended explorations have been completed and a careful 

 study of the material already collected has been made. 



The fossil mammals found during the past summer have not yet 

 been studied. Those described in the present paper were collected by 

 the writer in previous years extending back as far as 1895. 



EOCENE? 



Sage Creek Beds. 

 This formation occurs on Sage Creek about seven miles northeast of 

 Lima in Beaverhead County. Only four specimens were found that 

 are of any value in determining the age of the formation. One of 

 these {Heptodon ?) is undoubtedly Eocene. Two specimens that I 

 have referred to Hyrachyus were found, but one consists of a solitary 

 tooth \ and the other — a mandible, atlas, and part of a skull — looks 

 like a more modern form than we would expect to find associated with 

 Heptodon. The last specimen — a part of a mandible — has all the 

 peculiar characters of the corresponding portion of Metamynodon ? 

 but is very much smaller than the White River species. However, the 

 Hyrachyus skull was found a few feet under the specimen of Heptodon, 

 and the Metamynodon jaw a few feet under the stratum that contained 

 the solitary tooth which resembles Hyrachyus. 



145 



