SOME EARLY MAMMALS 



2 45 



1. Hyracotherium 

 = Protorohippus. 



2. Orohippus. 



3. Mesohippus 

 allied to the 

 Anchitherium. 



4. Merychippus 

 (Protohippus). 



5. Plioliippus. 



6. Equus caballus. 



FIG. 90. The Evolution of the horse. 1-5, ancestors of the horse restored in 



outline from fossil remains from the Lower Eocene to recent times. 



(H. S. Lull, American Jour. Science, vol. xxiii.) 



