Neither of these types, the Forest, the Desert type, or the Hipparion, 

 are known to be directly ancestral to the true modern horse Equus, and 

 one of the gaps still remaining for our exploration is to discover the 

 immediate ancestors of the true horse. It has long been known that 

 wild horses of great variety covered our country long before the period 

 of the Spaniards and probably long before the period of the first appear- 

 ance of man. The natural causes of the extinction of these splendid 

 native races are still unknown. Not improbably these animals were 

 swept away by an ei)idemic. 



UQULU tiCOTTI AND EOHIPl'U>S 



First and last stages in the Evolution of.tlie Horse in America 



Up to the time of our exploration only fragments of these native horses 

 had been found, together with a single fragmentary skull. Thus one of 

 the most important discoveries made in the whole twenty-two years 

 of exploration was the finding of remains of a herd of true horses near 

 Rock Creek, Briscoe County, Texas, by James W. Gidley, of the 

 Museum expedition of 1899. The herd consisted of seven skeletons, 



[28J 



