QUIDE 



TO 



THE HORSE FAMILY 



-. Although frequently employed in zoology in a wide 



I. u .. sense^ to indicate all the members of the family 

 Equid(Sj both living and extinct_, the term " Horse " 

 properly denotes only the well-known domesticated animal Equus 

 caballus and its half-wild or wild representatives. Since, more- 

 over, the Latin name was given by the Swedish naturalist Linnaeus, 

 it seems necessary to regard the domesticated Horses of Scandinavia 

 as the typical representatives of the species. 



In these pages the term Horse is niainly used in the more 

 restricted sense. 



Different views are entertained with regard to the limitations of 

 the family Equidce, some naturalists including in it all the extinct 

 animals belonging to the same line of descent, or "phylum/^ 

 while others restrict it to those more or less nearly related to the 

 living species. 



_. 11 In the latter sense the Equidce are characterized by 



the tall prismatic crowns and complex structure of 

 ^* their cheek-teeth, in which all the hollows and valleys 

 formed by the infoldings of enamel are filled by cement, so as to 

 form a grinding surface of a perfect type. Another feature is the 

 presence of an infolding of the enamel in the summits of the 

 incisors, thus producing what is called the '' mark.^^ In the skuil 



B 



