NO. I LOWER EOCENE MAMMALIAN FAUNAS — GAZIN 2/ 



tively. In the type of Gray Bull Teilhardella chardini these measure- 

 ments, near the same position, are about 2.05 and 1.15 mm. 



The bone of the jaw is broken away anterior to the forward root 

 of Mj, so that there is no information concerning the roots of P4. 

 M2 is characterized by a comparatively high crest formed by the 

 protoconid and metaconid, but the anterior crest of the trigonid is 

 very subdued and the paraconid is decidedly weaker than evident in 

 later apatemyids. The talonid basin, moreover, is rather shallow. 

 M2 is much larger than would have been included in the type of 

 T. chardini (P.U. No. 13236). Its anteroposterior and transverse 

 measurements are 2.0 and 1.3 mm. respectively. No direct comparison 

 with this earlier apatemyid is feasible as only P4 and M3 are pre- 

 served in the Princeton specimen. Nevertheless, the combined length 

 of Ml and Mg as measured at the alveoli can be compared, and in 

 T. chardini this is 2.7 mm. whereas in A. hiirseleri it is 3.4 mm. 



A. hiirseleri is rather close in size to Bridger Apatemys hellulus. 

 The incisor has about the same dimensions at the alveolus as in A.M. 

 No. 12048 and M2 is about the same length as in A.M. No. 12048 

 or as in Marsh's type, Y.P.M. No. 135 13. Its width, however, is very 

 much less. Also in A. hiirseleri the paraconid of M2 is distinctly 

 lower and weaker, the crest of the talonid in both Mi and M2 is 

 lower and the outer walls of the teeth do not bulge outward at the 

 cingulum so markedly as in the type of A. hellulus. 



The La Barge form is only a little larger than the earlier and 

 geographically more remote Teilhardella zvhitakeri. The dimensions 

 of M2 given by Simpson (1954, p. 4) are 1.7 and 1.2 mm. for the 

 anteroposterior and transverse diameters respectively. Moreover, 

 the depth of jaw below M2 on the lingual side is given as 3.6 mm. 

 This depth in the La Barge specimen is 4.8 mm. 



PRIMATES 



NOTHARCTIDAE 



PELYCODUS, cf. TRIGONODUS Matthew 



Three lower jaw portions and a third upper molar from the Bitter 

 Creek locality seem close to the species Pelycodus trigonodus that 

 Matthew described from the Gray Bull horizon in the Bighorn 

 Basin. The lower molars are indistinguishable from those in Gray 

 Bull lower jaws in the National Museum collection referred to this 

 species. P4 in U.S.N.M. No. 22256, however, seems relatively a little 

 larger than noted in the Gray Bull specimens ; nevertheless, in Y.P.M. 

 No. 14075 the correspondence in the size of this tooth is very close. 



