PREFACE 



Important skeletal remains of Eocene Primates of the genus Notharctus Leidy, including skulls, 

 teeth, and incomplete skeletons, were obtained in Middle Eocene strata of the Bridger Basin, Wyoming, 

 by American Museum expeditions under Mr. Walter Granger in 1903 and 1904. This delicate material 

 was freed from the matrix and prepared for study and exhibition chiefly by Mr. Albert Thomson. It 

 was generously assigned by Professor Osborn and Dr. Matthew to the writer to be described and com- 

 pared with the earlier collections of Eocene Primates in this Museum. These collections have already 

 been studied and described, as to their diagnostic generic and specific characters, in several papers in the 

 Bulletin of this Museum by Osborn (1902), Matthew (1915), and Granger and Gregory (1917), so that the 

 following pages deal chiefly with the morphology and evolution of the genus Notharctus and with the 

 relationships of the Notharctinse with other groups of primates. Preliminary reports on this subject 

 were made by the present writer in 1913, 1915, and 1916 in the papers cited in the bibliography. 



The auditory region and ossicles of Notharctus oshorni were very skilfully freed from the matrix by 

 Mr. Abram E. Anderson, who also prepared many other specimens and all the photographic illus- 

 trations for this work. The line drawings, unless otherwise noted, were drawn under the writer's 

 direction by Mrs. Ehzabeth M. Fulda. 



A few words of explanation may be offered as to the illustrations which are reproduced from the 

 works of other investigators. If, according to a conventional method, one had given drawings or photo- 

 graphs only of the Notharctus material itself, that would have been a sufficient record for the few investi- 

 gators who, in the course of future decades, would read the text with care and make their own detailed 

 comparisons after having duly assembled the literature of the subject and with their own specimens for 

 comparison in hand. But if (as the important nature of the material seems to warrant) it is desirable to 

 make the whole subject available also to a wider circle of scientists — specialists in other fields who have 

 neither the inclination nor the facilities for a first hand study of this material, — then it is necessary to 

 supply abundant comparative illustrations in order to show at a glance what are the resemblances and 

 differences between these Eocene Primates and other members of the same order. Accordingly the 

 writer has reproduced for comparison many of the excellent figures of the Eocene Primates of Europe 

 published by Dr. Stehlin in his Critical Catalogue of the Swiss Eocene mammals, and a few of the remark- 

 able engravings of the osteology and myology of recent indrisine lemurs in the memoir by Alilne Edwards 

 on the Anatomy of the Lemurs of Madagascar. Cuvier's and Laurillard's "Planches de Myologie" have 

 yielded se^"eral useful illustrations, and the same is true of other sources which are acknowledged in tlie 

 legends of the text figures. Some of the photographs of primate skulls which were made by Mr. Anderson 

 for the late Dr. ElUot's Monograph on the Primates have been carefully retouched and reproduced for 

 comparison Avith figures of the skull of Notharctus oshorni. 



