2 PROCEEDINGS OF THE NATIONAL, MUSEUM. ' vol. 63. 



to use a binocular microscope for much of the preparatory work as 

 well as for detailed study of the smaller forms. The collection, rep- 

 resenting as it does such a varied fauna, is proving to be most inter- 

 esting and important, not only in increasing our none too adequate 

 knowledge of earlier Tertiary mammahan life, but in its promise of 

 aid in solving some of the puzzling correlation problems of Paleocene 

 horizons in various localities of the Rocky Mountain region. At 

 least 40 species, most of them new to science, distributed among not 

 less than 15 families, and 6 or possibly 7 orders, are represented. A 

 few of the new species have been described by the present writer in 

 short papers,^ but now that the whole collection is available for de- 

 tailed comparison, it is proposed to continue the study by orders, or 

 great groups, the whole eventually to be combined in a single mono- 

 graph. The Primates form the basis for the present communication. 



DESCRIPTION OF SPECIES. 



Order PRIMATES. 



Up to the present time true Primates of unquestioned standing 

 have not been reported in America from beds older than Lower Eocene, 

 the Puerco and Torrejon having yielded nothing that could be re- 

 ferred with certainty to this order. However, it has been recognized 

 that some, at least, of the Eocene Primates show such marked degrees 

 of advance in development as to suggest a beginning much earlier 

 than the age of the beds (Wasatch and Bridger) in which they have 

 heretofore been found. It is not surprising, therefore, although of 

 the greatest interest, that remains of true Primates are actually found 

 to occur among the abundant faunas of the Fort Union Paleocene. 

 Some of these seem to show undoubted relationship to the already 

 known Primates of the Eocene, while others may represent hitherto 

 unknown groups. All, however, are in general more primitive in 

 type than their supposed relatives of later date, although their stage 

 of development is sufficiently advanced to indicate beyond question 

 that the greater groups, or families, to which they belong were almost 

 as definitely marked out at this earlier period as in the Eocene, and 

 lends abundant support to the suggestion that we must look to for- 

 mations very much older than the beginning of the Tertiary for evi- 

 dence, if ever found, of the much-sought root group, or beginning, 

 of the Primates as a distinct order. 



2 Notes on the fossil mammalian genus Ptilodus, with descriptions of new species. Proc. U. S. Nat. 

 Mus., vol. 36, 1909, pp. 611-626. 



An extinct marsupial from the Fort Union with notes on the Myrraecobidae and other families of this 

 group. Proc. U. S. Nat. Mus., vol. 48, 1915, pp. 395-402, pi. 23. 



Notice of a new Paleocene mammal, a possible relative of the Titanotheres. Proc. U. S. Nat. Mus., 

 vol. 52, 1917, pp. 431-4.35, pi. 36. 



New species of Claenodonts from the Fort Union (Basal Eocene) of Montana. Bull. Amer. Mus. Nat- 

 His., vol. 41, 1919, pp. 511-555. 



