30 EVOLUTION 



tion for speed." It is interesting to notice, 

 however, that among competent critics 

 of too hastily constructed pedigrees even 

 the severest do not in the least impugn the 

 doctrine of evolution. 



What seems clear is this, that in early 

 Eocene times there lived small five-toed 

 hoofed quadrupeds of generalized type, that 

 the descendants of these were gradually 

 specialized throughout long ages along similar, 

 but by and by divergent lines, that they lost 

 toe after toe till only the third remained, 

 that they became taller and swifter, that they 

 gained longer necks, more complex teeth and 

 larger brains. So from the short-legged splay- 

 footed plodders of the Eocene marshes there 

 were evolved light-footed horses running on 

 tiptoe on the dry plains. 



We can only refer to the importance for an 

 evolutionist outlook of thus trying to correlate 

 the changes in the animal with the changes 

 in the external conditions. The evolution of 

 the horse is wrapped up with the evolution 

 of the plains, and of their grasses also, for 

 these made their first appearance in Tertiary 

 times. The early ancestors probably lived in 

 the warm luxuriant forests, but as colder, 

 drier climate set in, and the forests shrank, 

 the progressive " hippoids " took more and 



