FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 259 



phagus. M^ is markedly reduced and very transverse, a resemblance 

 to Conacodon cophater but here somewhat intensified. 



In the lower molars the large swollen trigonids with the tips of the 

 cusps pinched together, giving an aspect difficult to describe but 

 characteristic when seen, is diagnostic of Anisonchinae and typically 

 developed in Coriphagus. The paraconids are retained and are closely 

 similar to those of Anisonchus gillianus, possibly a trifle more internal, 

 but hardly more so than in some specimens of that species; in A. sec- 

 torius they are more definitely median. The molar talonids are rela- 

 tively smaller and their cusps less conical and distinct, especially on 

 M3. This is perhaps the most aberrant feature of Coriphagus, con- 

 sidered as an anisonchine, but the difference from such a form as 

 Conacodon cophater is really slight. 



The characters of the mandible mentioned or shown by Matthew are 

 almost identical with those of other anisonchines about the same size. 



Coriphagus is in many respects the most primitive known anison- 

 chine, representing, in view of its age, an unprogressive surviving type. 

 Its closest comparisons are with Conacodon cophater and Anisonchus 

 gillianus, both Puerco species and older than the known species of 

 Coriphagus. Coriphagus carries still closer the marked resemblance 

 already noted between the anisonchine and the hyopsodontid denti- 

 tions. Were no other anisonchines known, it could very well be classed 

 as a hyopsodontid representing another incipiently divergent line in 

 addition to the several already known in that group. But all these 

 divergent characters are in the direction of the more specialized anison- 

 chines, and these in turn show marked resemblance to the still more 

 specialized periptychines. The whole hyopsodontid-periptychid com- 

 plex seems to bear the definite stamp of divergence from a common 

 ancestry. 



CORIPHAGUS MONTANUS Douglass 



Figures 75, 76 



Coriphagus montanus Douglass, 1908, p. 17. 



Type. — Carnegie Mus. no. 1669, left lower jaw with P2-M3. Col- 

 lected by A. C. Silberling. 



Horizon and locality. — Type from Silberling Quarry, several referred 

 specimens from Gidley Quarry, Fort Union, Middle Paleocene horizon, 

 Crazy Mountain Field, Mont. 



Diagnosis. — Smaller than C. encinensis (see measurements). Lower 

 teeth relatively narrow. M3 less reduced relative to other teeth. 



Discussion. — The differences in proportions given are not entirely 

 certain, since they depend on only one specimen of C. encinensis, and 

 these characters are variable. The size difference is slight and in 

 itself might not warrant full specific status, but its constant association 

 with different provenience makes it certainly significant. Every di- 



