ART. 1. PRIMATES OF THE FORT UNION — GIDLEY. 13 



It seems to hold about the same position in relation to Nothodectes 

 as does Pelycodus to Noiharctus. That is, PronotJiodectes has not 

 reached a stage so advanced as Nothodectes, and stands directly, or 

 nearly directly ancestral to the latter. It is clearly distinguished 

 from Plesiadapis, if reliance may be placed upon the figures and de- 

 scriptions of Lemoine, ^ by the somewhat more advanced modification 

 of the incisors combined with the less progressive condition of the 

 premolars. Also, Plesiadapis differs from the related American 

 Nothodectids in that the last upper molar, instead of the second, is 

 the largest of the series. 



Two upper incisors (Nos. 10005 and 10044 see pi. 3. figs. 11 and 

 12) of characteristic pattern, which are of appropriate size, are so 

 very closely like those of N. gidleyi as, by analogy, to leave little 

 doubt that they belong to the species here described. If this refer- 

 ence is correct, then the upper incisors of N. gidleyi and P. mattJiewi 

 are almost exactly alike in general structure, both differing very dis- 

 tinctly from those of the species of Plesiadapis figured by Lemoine. 

 The American species have a more elongate crown and the terminal 

 cuspules are more massive and less sharply pointed, giving them a 

 finger-like appearance. 



The fourth upper premolar in PronotJiodectes seems to be in about 

 the same stage of development as p^ of Nothodectes, and closely 

 resembles it in detail. 



The mode of complication tending toward the molariform pattern 

 in the hinder upper premolars of both the American genera (see pi. 

 3, fig. 3) is identical, and being peculiar, merits description. In 

 general, they are transversely expanded, three-rooted teeth, with 

 large protocone; well-developed protoconule situated in an unusual 

 position between and directly in line with the protocone and para- 

 cone; paracone external with metacone budding off from the summit 

 of its posterior flank but becoming progressively distinct. There is 

 also a posterior cingulum running inward and continuing upward to 

 the summit of the protocone, producing a more or less well defined 

 hypocone ridge and basin as in the molars. The upper premolars of 

 the other American members of this group are not known. But 

 according to Lemoine's figures the upper premolars of Plesiadapis 

 are of this peculiar type, suggesting that it is characteristic of the 

 Plesiadapidae group and confirms Matthew's observation of the close 

 relationship between Plesiadapis and Nothodectes. 



OTHER PECULIAR INCISORS OF UNCERTAIN REFERENCE. 

 Plate 3, Figures 8, 9, 10, 13, 14, and 15. 



In addition to the two incisors just described, there are in the 

 Fort Union collection several isolated ones which show sufficient 



•Bull. Soc. Geol. da France, ser. 3, vol. 19, 1S91, pp. 278-280, pi. 10. 



