OCEANIC ISLANDS. 245 



of a continental character, but we have no proof of this ; 

 and even if it were so, the existing islands are to all intents 

 and purposes oceanic. 



We will now pass on to a consideration of some of the 

 more interesting examples of these three classes, beginning 

 with oceanic islands. 



All the animals which now inhabit such oceanic islands 

 must either themselves have reached them by crossing the 

 ocean, or be the descendants of ancestors who did so. Let 

 us then see what are, in fact, the animal and vegetable in- 

 habitants 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 amon<]: several classes of animals. 



