1915.] Matthew and Granger, Lower Eocene Wasatch and Wind River Faunas. 477 
relatively, and the inner half of the tooth is not so broad, the posterior 
conule absent, the whole tooth more of the usual premolar type. Mesostyles 
are very rudimentary on m*’, none on p*. 
Cynodontomys angustidens sp. nov. 
Type, No. 15073, lower jaws from the middle part of the Gray Bull beds, Bighorn. 
Referred specimens, Nos. 15079-82, all from the same horizon. 
Distinctive characters: Pam; = 14.8 mm. Py, narrow and oval, with smaller 
heel, entoconid rudimentary and deuteroconid small, molars somewhat smaller and 
relatively narrower than in C. latidens. 
This species is distinctly more primitive and is not found above the 
Systemodon beds. Although the premolars are 
comparatively simple, they show no especial ap- 
proach to those of Miaodectes, and appear to be 
derived from a quite different type, more that of 
?Oxyacodon in the Paleocene. A jaw fragment 
with ps-me, No. (coll. 1913), from the upper fos- 
siliferous horizon in Clark Fork basin (lower Gray 
Bull beds) appears to represent a primitive mutant 
of this species, but part of the crown of the pre- 
molar is broken off and the presence of the meta- e 
conid cannot be determined. . ao Naw) 
The fourth upper premolar has a small postero- se 
external cusp, no conules, and less antero-posterior ieee! keh Ashe ald 
width than in the later species, and in general jaw with fourth premolar 
form is more clearly of premolar type. No meso- ee ean Pert 
style on m!. In the lower jaw, ps has a small in- Upper Gray Bull beds, Big- 
ternal cusp not well separated, and a simple 2°!™ basin, Wyoming. | 
crested heel with very rudimentary inner cusp, in place of the bicuspid 
heel of the later species. 
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A 
Famiry APATEMYIDA. 
Insectivora or Primates with low-crowned bunodont_ tritubercular 
molars, premolars greatly reduced and p; simple; one anterior tooth, 
probably an incisor, greatly enlarged and more or less gliriform; other 
anterior teeth reduced or absent. Posterior mental foramen beneath m; 
or M.. : 
The resemblance of the dentition in some genera of this family to that of 
Cheiromys (= Daubentonia) is closer than to any Insectivore. The teeth 
i ee 
