CONTENTS 



CHAPTER I 



THE HORSE'S PLACE IN NATURE — ITS ANCESTORS AND 

 RELATIONS 



PAGE 



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 — Significance 

 of rudimentary structures — Meaning of the term ' specialisa- 

 tion ' — Position of the horse in the animal kindom — Division 

 of ungulate mammals into perissodactyle and artiodactyle — 

 The horse belongs to the form er — Palseontological history 

 of the perissodactyles — Generalised ungulates of the earliest 

 Eocene age — Phenacodus — True perissodactyles — Hyraco- 

 therium — Palseotherium — Families 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 characters by which horses differ from 

 the generalised early forms of perissodactyles, probably all 

 adaptations to changed conditions of life — Present state and 

 probable future of the group 1 



CHAPTER II 



THE HORSE AND ITS NEAREST EXISTING RELATIONS 



The tapirs (Family Tajriridce) — Characters, species, geographical 

 and geological distribution — The rhinoceroses (Family 



