THE HORSE AND HIS PEDIGREE. 147 



enabled it to strike out new varieties in abund- 

 ance, even better adapted than itself to the condi- 

 tions of existence u[)on the broad table-lands of 

 the great continents. The fewer the toes, the 

 lirnier the tread ; and so, in a slightly later deposit, 

 we find that tlie still develoiting iiorse-like crea- 

 ture has lost the useless fifth toe on its front foot, 

 and has confined itself to four and tliree apiece 

 on its fore and hind limbs respectively. As we 

 trace the gradual evolution of the horse-kind 

 upward through the successive stages of the Terti- 

 ary rocks, we find the animals increasing in size 

 and diminishing in number of toes at each suc- 

 ceeding level of deposit. In the miocene beds of 

 Oregon and Nebraska we come first upon a pony- 

 like creature as big as a sheep, with only tliree 

 toes upon the front feet, all of them hoofed, but 

 with the central toe decidedly the biggest and the 

 most firndy [)lanted upon the ground beneath. It 

 is this big central toe that has finally developed 

 into the single hoof of our horses and donkeys, 

 growing ever larger, broader, and more solid, 

 while the side-toes grew progressively smaller, 

 shorter, and more useless. Hy the pliocene period, 

 once more, which succeeded the miocene, our de- 

 veloping horses have progressed from the size of 

 a sheep to that of a donkey; and each foot has 

 then got a large middle toe, on which the animal 

 walks firmly, flanked by two smaller and uinieces- 



