Article XVII.-AMERICAN EOCENE PRIMATES, AND THE SUPPOSED RODENT FAMILY MIXODECTIDAE. By HENRY FAIRFIELD OSBORN. The only American Primates at present known are those in the Eocene. The supposed Oligocene Primates, Laopithecus Marsh and Menotherium Cope, have proved to be identical with Leptochcerus Leidy, an Artiodactyl. Invariably associated with the discovery and literature of the Primates is the family Mixodectidae, including Mixodectes and possibly Indrodon, Cynodontomys, and Microsyops, now supposed to be very primitive Rodents. In the writings of Cope, Marsh, and Leidy, the bibliographical relations of these two groups are so intimate that it is convenient to revise them together. Altogether fifty-one species have been named, many of them based upon defective types; the synonymy is truly appalling, as shown in the chronological table. Many years ago I devoted several months to systematic revision as the basis of the present paper, examining and comparing the types in the collections made by Leidy, Marsh, and Cope, now in the Philadelphia Academy (Ph.), Ameri- can Museum (A. M.) and Yale University (Y.). Unfortu- nately all the types described by Cope for the Wheeler Survey, and figured in his 'Extinct Vertebrata of New Mexico' of I874 have disappeared. A beginning is made here by pointing out the synonymous genera but the species require prolonged and microscopic examination and comparison. This, however, is intended to supersede and replace all previous revisions by the author and his staff in the Museum. Dr. W. D. Matthew has rendered invaluable aid and advice both in the morphological and descriptive part. In putting together these notes and tables I have also been greatly assisted by Mr. W. K. Gregory. The drawings are chiefly the work of Mr. Weber, Mr. Horsfall, and Mr. Anderson. [I69] 170 Bulletin American Museum of Natural History. [Vol. XVI, PART I. PRIMATES. I. SUPPOSED BASAL EOCENE (MONTIEN AND THANETIEN) PRIMATES. None of the Basal Eocene (Puerco and Torrejon) types appear to be positively ancestral to the Lower Eocene or Wasatch Primates; the Primates of the latter stage (Sparna- cien) thus far appear to represent a new primate fauna like the new ungulate fauna of horses, tapirs, etc. The Puerco and Torrejon species include a great number and variety of small animals whose relationships are still largely a matter of individual opinion, because the material, except in the case of one skeleton (No. 823, see below), affords no absolutely distinctive characters. They have been referred by different authors, chiefly Cope, Schlosser, Earle, and Osborn,to such m p.4 -'4~~~~ diverse orders as the Creodonta, Rodentia, Condy- larthra, Insecti- vora, andPrimates. g I have always in- 'Vlined to refer manyof the smaller 21 B2 types to the Pri- mates, but without being able to give conclusive grounds for the opinion, the main reason being the general adap- tive resemblance which they bear to Fig. I. A, Mioclznus acolytus. Amer. Mus. No. 829a. Lower molar. B, supposed Primate. Am. Mus. No. 823. the existing Le- B2 superior molars, enlarged 2 diam., B', contour of same still more enlarged. C, lower jaw of same specimen, 2 diam. murs. Compare Fig. 2. Twice natural size. Indrodon malaris (Torrejon stage) was placed by Cope in the Anapto- morphidae; this is an error. The structure of the superior rg02.] Osborn, American Eocene Primates. I71 molar teeth relates it rather to Mixodectes, a supposed primitive Ro- dent. The skeleton (Amer. Mus. No. 823) originally associated with Indrodon by error (Osbom and Earle, I895, pp. I6-20) deserves most careful examination, for if it belongs to a Primate it is by far the most primitive known. The astragalus is not like that of a Rodent. The figures (Figs. I, 2) give the proportions of the limbs. I Miocl ,nus acolytus and M. lemuroides Mat- thew are two other small Torrejon species inwhich U. the lower molar teeth suggest those of Hyop- sodus, especially in the reduction of the para- conid (Fig. iA). Oxyacodon apiculatus (Puerco) and 0. agapetil- lus (Puerco), also Car- c inodon filholianus (Puerco), deserve ex- amination in this con- Fig. 2. Supposed Primate. Am. Mus. No. 823. nection. Fore and hind limb bones and tarsals. All natural size. 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', 00~~~,6. m0 00 ..0.CC)0000~~~~~PL ~~H*,* 0) I-00' 00.0 0*QH 0000)0)4 600 08 rn 00'3 i00.C0 .00 0),5 0)~~~~~~~~~ 0 00 Z - .0, -0c 0)- o..-'u:. r000 CC006>.4000C05..om 6 A 000000H H 04004cM 04co0.5 0..0M coPACdP-4 ~ ~.4CM~ ~ ~ ~ ~ ~ ~ ~ ~ '0) ~~1 o-. 0)~~O c) S 00 0)"C ~ 0 0 . 4 O) 0a 00 0 0 0 00 0 00 00 0.W . °^0O . N 0 H H in & \ O0 Q 00 WatA§2 g C 'z 0. 0\0 di wP0A~ (34 zE,L 0)~~~~~~~~~~~~~~~~~~ 8Lv 0 )c0 i L 0 C.) 0) 0) 0 C 0 0) Id 0) 0 0) 0) 0 V)(3 t .b00 'O0 0 ) \ 0 '. E _ _ _/ E s -o/ -_ _ _ s _ _E _ .I [I 75]o ['75] I 7-6 Bulletin American Museum of Natural History. [Vol. XVI, II. LOWER, MIDDLE, AND UPPER EOCENE PRIMATES. (SPARNACIEN, YPRESIEN, LUTE'TIEN, BARTONIEN, LIGURIEN.) Originating in the lower Eocene or Wasatch (Sparnacien, Ypr6sien) of North America are found three phyla of Pri- mates, quite distinct from those in Europe. i. The HYOPSODONTIDAI are analogous in certain respects of molar tooth structure to the Microchoeridae of Europe, but are distinct in the simple cutting teeth. 2. The NOTHARCTIDRE resemble in size and general form the contemporaneous Adapidae of Europe, but the much more complex structure of the upper molars constitutes good grounds for not placing them in the same family.