Douglass : Vertkbraiks !• RO>r Montana Tertfary. 159 



pressed and low. It is much lower than the other three ])rincipal 

 cusps. There is a strong anterior cinguluni and a weaker one on the 

 outside of the outer exterior style. 



Mkasuremknts. 



Mm. 



Length of M-'' 13 



Width of M' 16 



Height of antero- internal cusp g 



From Sage Creek about seven miles northeast of T.ima. 



Meta.mynodon? 

 No. 734. 



A horizontal ramus of a mandible with the alveoli and roots of the 

 teeth. 



This jaw is somewhat puzzling. It was found in the beds on Sage 

 creek in a sandy lens or layer lower down than the stratum from which 

 the Hyrachyiis ? tooth (No. 718) was obtained and not far away. 

 This specimen if found in the White River would be unhesitatingly 

 referred to the genus J\[etamy)wdon, though it is very much smaller 

 than M. planifrons. But there is the same reduction in number of 

 the incisors and premolars, the enormous enlargement of the canines, 

 the great lengthening of the symphysis and narrowing of the pre- 

 molars. In minor details, too, it is the same, about the only differ- 

 ences being the smaller size, the more procumbent position of the 

 canines, and the thinner horizontal ramus. 



The last incisors were quite large and in contact with the canines. 

 There were probably second incisors, but they were very small. Part 

 of the alveolus of one can be seen. The three premolars were all 

 small. The root of the canines was very large and the two nearly 

 came in contact. They occupied the greater part of the symphysis. 

 There is a longitudinal convexity on the outer side of the one pre- 

 served. The symphysis extends backward to P^ and the posterior 

 part is wide. 



One would not expect to find an animal apparently so like Metamy- 

 nodon in the Middle Eocene, but the data are given for what they are 

 worth. 



