THE ANCESTRY OF THE HORSE 173 
titles as “Clique, the horse with six feet,” 
“the eight-footed Cuban horse,” and so on ; 
and possibly some of these are familiar to 
readers of this page. 
_ So the collateral evidence, though scanty, 
j bears out the circumstantial proof, derived 
from fossil bones, that the horse has developed 
from a many-toed ancestor; and the evidence 
points toward the little Hyracothere as being 
that ancestor. It remains only to show some 
good reason why this development should 
have taken place, or to indicate the forces by 
which it was brought about. We have heard 
“much about “the survival of the fittest,” a 
phrase which simply means that those animals 
best adapted to their surroundings will sur- 
' 
vive, while those ill adapted will perish. But 
it should be added that it means also that the 
‘animals must be able to adapt themselves to 
changes in their environment, or to change 
with it. Living beings cannot stand still in- . 
definitely ; they must progress or perish. And 
' this seems to have been the cause for the ex- 
tinction of the huge quadrupeds that flour- 
ished at the time of the three-toed Miocene 
ee 
