18 THE HORSE. 



mencement of the Tertiary period. At present the 

 balance of evidence is rather in favor of their rela- 

 tionship with the earlier and more primitive forms 

 just mentioned. We have, however, certain knowl- 

 edge that when the land which formed the bottom 

 of the great cretaceous ocean which flowed over a 

 considerable part of the present continents of Europe 

 and North America was Hf ted above the level of the 

 water and became fitted to be the abode of terrestrial 

 animals, it was very soon the habitation of vast num- 

 bers of herbivorous and hoofed mammals. 



The remains of animals to which it is possible to 

 trace back the modern horse by a series of successive 

 modifications without any great break are found in 

 abundance in the lower strata of the great lacustrine 

 formations assigned to the Eocene period spread over 

 considerable portions of the present territories of 

 New Mexico, "Wyoming, and Utah, in North America. 

 Similar animals also existed in other parts of the 

 world, but in Europe the hitherto-discovered frag- 

 ments which prove their existence are in a less com- 

 plete and satisfactory condition for investigation. 

 Negative evidence is in such cases, however, of little 

 value, as may be judged from the fact that it is only 

 within a very few years that the existence of these 

 American deposits teeming with fossil remains of 

 previously unsuspected forms of life has been brought 



