178 



EVOLUTION AND GENETICS 



Eohippus, the ''Dawn Horse," was a small animal, about the 

 size of a fox terrier (Fig. 103). Its head was elongate and rather 

 horse-like, although the eye was much farther forward than in 

 modern horses. The feet were digitigrade, and the legs onl}^ 

 moderately elongated, hence the neck was also moderate. The 

 fore limbs had four functional digits, the second to fifth, while the 





Fig. 103. — Restoration ul' Kulnppu-i .sp. ul ilit* luuei li,oceiie. (I'Vom Scolt.) 



first was completely lost. The hind limbs were three-toed, with 

 minute vestiges of the first and fifth (Fig. 104). Each lower limb 

 retained the two primitive bones, the radius and ulna of the fore 

 limbs and the tibia and fibula of the hind limbs. The teeth were 

 relatively advanced, foreshadowing the modifications to come, 

 but the premolars were still distinct from the molars and the first 

 premolars were present (Fig. 105). Correlated with this primitive 

 condition of the teeth is the relative shallowness of the jaws and 

 the position of the eye. The conditions under which the species 

 lived were such as to encourage the development of grazing habits 

 because of the abundance of meadows and grassy plains. In spite 

 of such facts, however, these little creatures are conspicuously 

 unhke the modern horses. It is only through the intermediate 

 forms that the two extremes can be associated. 



