THE HORSE. 



CHAPTER I. 



THE HORSE'S PLACE IN NATURE — ITS ANCESTORS AND 



RELATIONS. 



Interest of the study of the horse, especially as illustrating 

 some important principles in biology — A test case of the 

 value of the theory of transmutation of species — Signifi- 

 cance of rudimentary structures — Meaning of the term 

 " specialization" — Position of the horse in the animal king- 

 dom — Division of ungulate mammals into perissodactyle 

 and artiodactyle — The horse belongs to the former — Pa- 

 lseontological history of the perissodactvles — Generalized 

 ungulates of the earliest Eocene age — Phenacodus — True 

 perissodactyles — Hyracotherium — Pala?otherium — Fami- 

 lies which became extinct without leaving descendants — 

 Three surviving families, represented at the present time 

 by the Tapirs, Rhinoceroses, and Horses — The first the 

 least and the last the most modified — Principal charac- 

 ters by which horses differ from the generalized early 

 forms of perissodactyles, probably all adaptations to 

 changed conditions of life — Present state and probable 

 future of the group. 



The horse is from many points of view one of 

 the most interesting of animals. In utility to man it 

 yields to no other. It was his domestic companion, 



