CONTENTS 



CHAPTER I. 



PAGE 



THE HORSE'S PLACE IN NATURE ITS ANCESTORS AND 

 RELATIONS 1 



Interest of the study of the horse, especially as illustrat- 

 ing some important principles in biology A test case of 

 the value of the theory of transmutation of species Sig- 

 nificance 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 Paleeonto- 

 logical history of the perissodactyles Generalized ungulates 

 of the earliest Eocene age Phenacodus True perissodac- 

 tyles Hyracotherium Palseotherium Families which be- 

 came extinct without leaving descendants Three surviv- 

 ing families, represented at the present time by the Ta- 

 pirs, Rhinoceroses, and Horses The first the least and the 

 last the most modified Principal characters by which 

 horses differ from the generalized early forms of perissodac- 

 tyles, probably all adaptations to changed conditions of life 

 Present state and probable future of the group. 



CHAPTER II. 



THE HORSE AND ITS NEAREST EXISTING RELATIONS . . 45 



The tapirs (Family Tapiridai) Characters, species, geo- 

 graphical and geological distribution The rhinoceroses 

 (Family RMnocerotidce) The horses (Family Equidm) 

 Their immediate predecessors The hipparions, or three- 



