1915.] Matthew and Granger, Lower Eocene Wasatch and Wind River Faunas. 87< 
The milk dentition has not hitherto been known in this genus. The 
first premolar is one-rooted, and belongs apparently to the permanent series. 
The appearance of the first permanent premolar with or shortly after the 
succeeding milk premolars has also been observed by Wortman in Hyenodon. 
Dp» is small, compressed, two-rooted, with indistinct heel; dps and dps are 
narrow elongate compressed teeth with large anterior cusps (paraconids) 
and long trenchant heels, both paraconid and heel being relatively much 
larger than in the true molars, while the protoconid is small. They differ 
widely from the corresponding teeth in Pachyena gigantea (see p. 97) both 
in proportions and the development of paraconid and heel; the milk denti- 
tion of the smaller species of Pachyena is not known. 
Dissacus prenuntius sp. nov. 
Type, No. 16069, upper and lower teeth and fragments from Clark Fork Beds, 
Wyoming. ) | 
Distinctive characters: Smaller than D. saurognathus; larger than D. navajovius; 
paraconids of molars much.smaller than in either species; metacone of m° vestigial. 
This species is represented by but a single individual. The reduction of 
the anterior basal cusps on py and on the molars preserved would seem to be 
a primitive character, preserved on m3 in D. saurognathus and navajovius, 
but not on ps-ms. In the present species the paraconid is much more 
reduced on ps, and is quite small on two incomplete molars which are, 
probably but not certainly, me right and left. The first upper molar is 
decidedly smaller than the m! of D. saurognathus,' about equally larger than 
the corresponding tooth in D. navajovius, and closely resembles the m! of 
Pachyena. The distal end of the humerus, the patella, tuber calcis and two 
phalanges indicate a species scarcely exceeding D. navajovius in size of limbs 
and feet, although the teeth are so much larger. 
Pachyena Cope 1874. 
Type, P. ossifraga from Wasatch of New Mexico. ; 
Generic characters: Molars $; metaconids vestigial ; paraconids large on ps-Ms; 
pollex much reduced, probably vestigial. 
Although originally described from a New Mexican specimen this genus 
is practically limited to the Gray Bull horizon of the Big Horn Wasatch. 
No additional specimens have been found in New Mexico nor in the later 
1 M2? of Osborn and Earle’s figure. 
2 Rep. Vert. Foss. New Mex., p. 13. 
