CHAP. XI.] 
OCEANIC ISLANDS. 
237 
either themselves have reached them by crossing the ocean, or he 
the descendants of ancestors who did so. Let us then see what 
are, in fact, the animal and vegetable inhabitants of these islands, 
and how far their presence can be accounted for. We will begin 
with the Azores, or Western Islands, because they have been 
thoroughly well explored by naturalists, and in their peculiarities 
afford us an important clue to some of the most efficient means 
of distribution among several classes of animals. 
