734 TERISSODACTYLS xxx. 9 



for the deep, continually growing teeth and for the large jaw-muscles, 

 and there is a complete post-orbital bar. 



S.AMERICA - 50 



EURASIA 



NORTH AMERICA 



Fig. 489. Table to show the evolution of horses. (Based on Stirton.) The approximate 

 condition of the limbs and teeth at each epoch are shown to the left and right. 



The hair is long all over the body and tends to show the pattern of 

 vertical stripes that is so marked in zebras, often clear in asses, and 

 occasionally present in horses. The tail is long, its hairs beginning 

 close to the base in horses, half-way along in the others. 



All horses in the native state live in herds, as do so many herbivores 



