GEOLOGICAL HISTORY OF THE PRIMATES 607 



monkeys are still one of the most remarkable problems in 



mammalian zoology. 



Another point which is of special interest to anthropologists 



is that, according to the indications which we possess at present, 



the evolution of the Catarrhina as a distinct group took place 



in Africa. 



REFERENCES 



1. Scott, Berryman. History of Land Mammals in the Western Hemisphere, 



1913- 



2. Osborn, H. F. The Age of Mammals. 1910. 



3. Scharff, R. E. Distribution and Origin of Life in America, igii, 



4. Matthew, W. D. " Climate and Evolution," Ann. N.Y. Acad. Set. 



Vol. XXIV. 1915 



5. Gregory, W. K. " Studies in the Evolution of the Primates," Bull. 



Amer. Mus. Nat. Hist., Vol. XXV. 1916. 



6. Gadow, Hans. The Wanderings of Animals. 1913. 



7. Pilgrim, G. E. " New Siwalik Primates," Records of Geol. Survey, 



India, Vol. XLIII. 1913. 



8. Abel, O. Die Stdmme der Wirbeltiere. 1919. 



9. Schlosser, M. " Beitrage zur Kenntniss der Oligozanen Landsaugetieren 



aus dem Fayum, Aegyten," Beit, zur Pal. u. Geol. Oest.-Ung., Band 

 xxiv. 1912. 

 10. Andrews, C. W. A Descriptive Catalogue of the Tertiary Vertebrata of 

 the Fayum, Egypt. 1906. 



EXPLANATION OF DIAGRAM 



The Diagram shows the distribution in time and space of the terrestrial 

 orders of Placental Mammals, as described in the text. 



A = the Mainland. 

 B = South America. 

 C = Africa. 

 D = Madagascar. 



The names in large type are those of orders whose presence at the particular 

 time and place is only a matter of inference from geographical distribution. 



The extinct orders are starred thus : X. 



As stated in the text, the chief element of uncertainty is the date of the 

 separation of A and C. I have assumed that it occurred at about the transi- 

 tion from Paleocene to Eocene conditions. 



For the information of the general reader it may be added that the Ambly- 

 poda and Condylarthra are archaic ungulates, the Trituberculata are a group 

 of Mesozoic mammals, believed to be placentals, the Taeniodonta are archaic 

 edentates, the Ancylopoda are ungulates, and Tillodontia are a group of 

 aberrant insectivores, the Pholidota are the pangolins, and the Tubulidentata 

 are the aardvarks. These groups are included for completeness, although 

 they are not all mentioned in the text. 



