62 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 128 



such advanced types as Protoreodon p. annectens or the small Pro- 

 toreodon ipetersoni. The mesostyles, as noted by Peterson, may be 

 divided and project anteroposteriorly, but do not project buccally 

 nearly so much as in the more-selenodont forms of Protoreodon. 

 Moreover, the molars are relatively wider transversely than in the 

 Protoreodon material I have examined. 



Diplobunops, like Protoreodon, is, of course, not closely related to 

 the bothriodonts although there is some resemblance in molar form. 

 The specialization of Pi rather than C as the functional caniniform 

 tooth, as well as other differences, indicates agriochoerid affinities. 

 Neither is Diplobunops the ancestor of Agriochoerus, as certain of 

 its specializations, such as the transversely expanded rostrum anteri- 

 orly, more nearly enclosed orbit, etc., together with its retention of a 

 more-primitive cheek tooth dentition even in the Duchesne River beds, 

 suggest aberrance. 



DIPLOBUNOPS MATTHEWIso Peterson, 1919 

 Plates 10, II, and 12 



Synonyms. — Diplobunops uintensis Peterson, 1931. 

 Diplobunops ultimus Peterson, 1931. 



Type. — Much fragmentary skeletal material, CM. No. 2974, also 

 including portions of maxillae and jaws with the upper teeth broken 

 or missing, but with P3, P4, M2, and M3 represented in the lower 

 series (originally designated as a paratype, CM. No. 3394, but later 

 recognized by Peterson as a part of the type). 



Horizon and locality. — Near base of Uinta C, 6 miles east of Myton, 

 Uinta County, Utah. 



Discussion. — Peterson (1931a, p. 344) indicated that teeth in 

 Diplobunops matthewi were approximately equal in size to those in the 

 type of "Protagriochoerus annectens." Actually, the former are about 

 15 percent larger in such dimensions as may be compared. The pre- 

 served lower teeth are relatively much wider transversely than in re- 

 ferred Protoreodon p. annectens material in both the premolar and 

 molar portions, and the lower jaws are conspicuously thicker. The 

 type of D. matthewi exhibits the very large canine and isolation of 

 P^ by diastemata characterizing the genus. 



I find nothing in the type skull of Diplobunops uintensis in com- 

 parison with the limited material of D. matthewi which would serve 

 to distinguish the second species. Peterson apparently looked forward 

 to the finding of additional material of D. matthewi in beds of lower 



30 Also illustrated in Peterson, 1919, pi. 38, and 1931a, figs. 1-9, pis. 19, 20. 



