1915.] Matthew and Granger, Lower Eocene Wasatch and Wind River Faunas. oad 
ao 
Hyopsodus powellianus Corr, 1885, Tertiary Vertebrata, p. 235, pl. xxuid, fig. 
3-4; OSBORN, 1902, Bull. A. M. N. H., Vol. XVI, p. 184, fig. 9. 
Phenacodus laticuneus Corr, 1882, in part, see infra, p.? 
L'ype (lectotype), No. 4147, lower jaw with m,-3. Horizon unrecorded, 
Bighorn basin, Wyoming. 
Characters: M,-3 = 18 mm. Ms with long heel, entoeonid distinct. 
Hypocones of m'? strong, antero-internal cingula heavy, p* subquadrate. 
Ps with well developed deuteroconid. 
This species is very abundant in the Lysite horizon, in the Bighorn basin. 
So far as our material shows it is wholly confined to this level, although 
Loomis records two specimens from the Gray Bull (but possibly these are 
Fig. 6. Hyopsodus powellianus Cope, topotype, upper jaw, No. 15622. Crown view of 
upper teeth, left side enlarged three diameters. The premolars are reversed from the right 
maxilla. Lysite beds, Coyote Cafion, Bighorn basin, Wyoming. 
\ \Z yy Ng s yy 
ML? Sail y 
iv 
ih 
= 
LS 
s 
A a A 
Fig. 7. Hyopsodus powellianus, topotype, No. 15614, lower jaw, three diameters, 
Lysite beds, Fifteen-mile Creek, Bighorn basin, Wyoming. 
