﻿part 1] ANNIVERSARY ADDRESS OF THE PRESIDENT. kxi 



Survey, in a superficial deposit in the Luckau district south of 

 Berlin. 



A detailed study of the tooth-pattern in the successive groups 

 of extinct Horses, seems to reveal the same phenomenon that is 

 observable in the Rhinoceroses — the approach to nearly-identical 

 extreme specialization by several separate lineages in approximately 

 the same time. The earliest Eocene forerunners of the Horses are 

 essentially similar in Europe and in North America, and some of 

 the later forms also exhibit many resemblances Avhich may be due 

 to migrations from one region to the other ; but the most ex- 

 haustive modern researches leave no doubt that the gradual 

 reduction of the foot to a single toe and the deepening of the 

 teeth for effective grinding of hard food, with various correlated 

 specializations, occurred in several distinct groups of Horses in 

 different localities. The climax was reached during the Pliocene 

 Period, both in Europe and Asia and in North America ; while 

 the greatest diversity of form appeared in the latter region and 

 among the immigrants to South America, where all Horses died 

 out before historic times. 



Even in families of more restricted geographical range, the 

 same unswerving tendency towards a fixed goal is very clearly 

 recognizable. Among the Camels, for instance, which seem to 

 have accomplished the whole of their evolution in part of North 

 America, the characteristic cushioned foot appears to have been 

 produced more than once. All the small early ancestors of the 

 Camels had feet like those of deer or gazelles, with pointed toes ; 

 and Prof. W. B. Scott has observed that even the Lower Miocene 

 genera, which were already differentiated into two groups, still 

 exhibited the same primitive feature. All the later Miocene 

 Camels of both these groups, however, possess the irregularly- 

 nodular ungual phalanges which indicate the presence of the 

 cushions or pads. It is thus evident that two progressive series 

 independently acquired one and the' same structure. 



A study of the extinct representatives of several other familiar 

 Ungulata has led to the discovery of many facts which tend to 

 confirm the results just mentioned. In every case, either the feet 

 become perfectly adapted for rapid locomotion over hard ground, 

 or the teeth acquire more grinding power by deepening, folding, 

 and the frequent infilling of the hollows with cement ; or both 

 these progressive adaptations take place at the same time. When, 

 however, this evolution first started in the Eocene Period, the 



