306 



LAND MAMMALS IN THE WESTERN HEMISPHERE 



(7) The feet were much elongated and the median (3d) 

 digit of each gradually enlarged until it carried the whole 



Fig. 155. — Right manus and left pes of 

 Equus. 



Fig. 156. — Right manus and left pes of 

 t Protohippus. 



weight, at the same time modifying the shape of the hoof so as 

 to fit it to be the sole support of the body. The other toes 

 gradually dwindled and became functionless, though often 

 retained as splints. The first digit (pollex and hallux) was first 



