284 THE WASATCH FAUNA. 



cies to this genus but for the tact that it appears to have but three superior 

 premolars, wliile Prouivena has four. 

 But one species is known. 



DiDELPHODUS ABSAHOK^ CopC. 



American Naturalist, 1882, June; Dellatherium absarokm Copo, 1. c. 1881, p. 669. 



Plate XXIV e; fig. 13. 



This animal repeats very closely the characters of the D. fundamims, 

 but is much smaller in all its proportions. Both branches of the lower jaw 

 accompany the anterior part of the skull, so that the dentition is well dis- 

 played. There are three inferior tubercular-sectorial molars, as in Stypoh- 

 phus, but the fourth premolar has an internal tubercle, which is not found 

 in that genus. The same tooth has a rudimental heel, which sends an angle 

 up on the inner side of the crown, which is then deflected and terminates 

 below in the rudimental anterior basal tubercle. The apical angle is little 

 produced, and constitutes the internal cusp above mentioned. The third 

 inferior premolar is large, has a rudimental heel, and no inner lobe; the 

 first premolar is two-rooted. There are only three inferior incisors. The 

 inferior canines have an open groove on the inner side and a rib on the ex- 

 ternal side. The latter is bounded anteriorly and posteriorly by a shallow 

 open groove. The symphysis is long and oblique; it extends posteriorly 

 to below the front of the third premolar. The posterior mental foramen is 

 below the posterior side of the same tootli, and the anterior one is below 

 the first premolar tooth. 



The superior molars are triangular, and the external posterior angle is 

 not produced. The external cusp of the fourth premolar is compressed and 

 simple, as in Proviverra; in Stypolophus {Prototomus) viverrinus and S. mul- 

 ticuspis, that tooth has a conic cusp and large posterior heel. The crowns 

 of the sQcond and third premolars are quite elongate and acute, and the 

 third has a small posterior basal lobe. On the external base of the fourth 

 are very small anterior and posterior lobes. The principal cusps of all the 

 true molars are double, and stand on the middle of the transverse diameter 

 of the crown. This leaves an extensive obliquely sloping external face, 

 which terminates exteruall}' by a narrow cingulum. The two cusps are well 



