® 
2 THE DARWINIAN HYPOTHESIS 7 
distribution of animals and plants it seems 
utterly hopeless to attempt to understand the 
_ strange and apparently capricious relations which 
they exhibit. One would be inclined to suppose 
_@ priori that every country must be naturally 
pespled_by th ‘those animals that are fittest to live 
and thrive in » in it. “And y yet how, on this hypothesis, 
are we to account for the absence of cattle in the 
Pampas “of South America, when those parts of_ 
__the New Wor World were discovered, 2 Tt is not that 
they were unfit for cattle, for millions of cattle 
now run wild there; and the like holds good of 
Australia and New Zealand. It is a curious 
circumstance, in fact, that the animals and plants 
of the Northern Hemisphere are not only as well 
adapted to live in the Southern Hemisphere as 
its own autochthones, but are, in many cases, 
absolutely better adapted, and so overrun and 
extirpate the aborigines. Clearly, therefore, the 
Species wie which naturally inhabit a country_are—not 
necessarily ily the best_adapted_to its climate and 
other conditions. The inhabitants of islands are 
often distinct from any other known species of 
animal or plants (witness our recent examples 
from the work of Sir Emerson Tennent, on 
Ceylon), and yet they have almost always a sort 
of general family resemblance to the animals and 
plants of the nearest maimland. On the other 
hand, there is hardly a species of fish, shell, or 
crab common to the opposite sides of the narrow 
