449 Bulletin American Museum of Natural History. [Vol. XXXIV 
4 
ae Wis 
Sw LY hse A 
z, ZN fa <) nl 5 
OM a, a Oe) AA 
: Oa y \ wl ) ) 4 iL fi wy | 
3 ie ee BY 
artery 
ae a Saar 
No. /620F = 2 
LONE, mu 
» MMA SONG 
OAS 
iene ae 
Cll 
Fig. 15. Pelycodus tutus, lower jaw, inner, outer and crown views. Top of lower (Al- 
magre) beds of Wasatch, San Juan basin, New Mexico. 
Osborn in 1902 distinguished Notharctus from Pelycodus by the above 
characters, and showed that P. nunienus Cope and P. venticolus Osborn of 
the Wind River were referable to the Bridger genus. They are distin- 
guished from most of the Bridger species by the symphysis of the jaw, which 
is In no instance codssified. One small Bridger species retains this primitive 
character but it is lost in all the others. The two species from the Lower 
Eocene are from the Lost Cabin horizon, and are separable from each. other 
chiefly by size, although the larger species is the more progressive. I 
regard them as progressive stages of Pelycodus frugworus and P. jurrowi 
respectively. 
The three species referred by Loomis to Notharctus do not appear to 
me to pertain to that genus. N. palmeri and N. cngulatus I refer to Cyno- 
dontomys latidens; N.minutus appears to be a small Omomys. 
