74 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 



suppressed; the upper end fuses with the tibia, while the lower remains 

 as a small separate bone, wedged in between the tibia and the heel- 

 bone. The feet are very long and slender, with two toes in each ; the 



FIG. 3. Four stages in the evolution of the cameline skull. A , Protylopus, 

 Upper Eocene; B, Poebrotherium, Lower Oligocene; C, Procamelus, Upper Miocene; 

 D, guanaco, Recent. (From Scott.) 



long bones of the foot are co-ossified to form a "cannon-bone,'' the 

 very young skeleton showing that this co-ossification does actually take 

 place. The toes proper are free, giving the "cloven hoof," but the 

 hoofs are very small and the weight is carried upon a soft, thick pad. 



