SOME EARLY MAMMALS 243 



was a graceful little creature about fourteen inches (four and 



, Js 



FIG. 89. Skulls and bones of fossil horses showing evolution of the horse, 



from casts in the Natural History Museum, London. 



1. Protorohippus ( = Hyracotlierium.) 2. Mesohippus. 3. Protohippus. 



4. Hipparion. 5. Equus caballus. 



a half hands) high at the withers. The next stage is seen in 



