﻿part 1] ANNIVERSARY ADDRESS OF THE PRESIDENT. lxix 



some o£ them (Me gal a dap is) almost rivalling donkeys in size; 

 they also diverged for various modes of life, a few of them even 

 entering the proper sphere of hoofed animals. Removed from the 

 stress of competition with other mammals such as swarmed on 

 the continents, they flourished in luxurious ease ; and we are 

 tempted to speculate whether it was not the strenuous competition 

 in the crowded continental forests of America and Africa (or Asia) 

 that made the difference, and led to the increase of Drain-power 

 which is the specially distinctive characteristic of Monkeys. If 

 this be so, the lower race passed into the higher race only where 

 t]ie struggle for existence was keenest. Why the higher race 

 never advanced further in America, while it began at once to give 

 rise to the man-like Apes in the Old World, is still an unsolved 

 problem. 



The case of the Anthropoidea suggests that a widely-distributed 

 group of early Tertiary mammals experienced in three separate 

 regions an essentially-similar initial impulse to become a higher 

 group, evolved on parallel though not identical lines, and ended at 

 v three different stages in its onward progress. It is, therefore, 

 interesting to consider the geological history of some of the families 

 of Ungulata which are already sufficiently well known by a succes- 

 sion of fossils to reveal the main episodes in their career. This 

 history is especially instructive, because all the surviving groups 

 originated in the Northern Hemisphere on two or three large 

 continental areas which were sometimes united, at other times 

 separate ; and the fossils are beginning to show how and when the 

 various connexions and isolations occurred. Northern Africa, 

 probably with part of Southern Asia, is one of the areas on which 

 Ungulates made an independent start ; Europe, with North-Central 

 Asia, is another ; while North America is the third. 



The Rhinoceroses are a well-marked family, of which numerous 

 fragmentary fossil remains can easily be recognized and compared. 

 They seem to have arisen at the beginning of the Eocene Pei'iod 

 from some small generalized Perissodactyl which had a slender 

 snout and a regular close series of 22 low-crowned teeth in each 

 jaw ; and, as ages passed, the nasal bones became enlarged and 

 thickened to support a dermal horn, the front teeth tended to 

 disappear as the lips became more prehensile, while the molars and 

 premolars increased in effectiveness for grinding hard and dry 

 herbage. As in other Perissodactyls, the premolars were at first 

 comparatively simple, but afterwards gradually approached the 



