390 GEOGRAPHICAL DISTRIBUTION. Chap. XII. 



plants ; yet many have become naturalised on it, 

 as they have on New Zealand and on every other 

 oceanic island which can be named. In St. Helena 

 there is reason to believe that the naturalised plants 

 and animals have nearly or quite exterminated many 

 native productions. He who admits the doctrine of 

 the creation of each separate species, will have to 

 admit, that a sufficient number of the best adapted 

 plants and animals have not been created on oceanic 

 islands ; for man has unintentionally stocked them from 

 various sources far more fully and perfectly than has 

 nature. 



Although in oceanic islands the number of kinds 

 of inhabitants is scanty, the proportion of endemic 

 species (». e. those found nowhere else in the world) 

 is often extremely large. If we compare, for instance, 

 the number of the endemic land-shells in Madeira, or 

 of the endemic birds in the Galapagos Archipelago, with 

 the number found on any continent, and then compare 

 the area of the islands with that of the continent, we 

 shall see that this is true. This fact might have been 

 expected on my theory, for, as already explained, spe- 

 cies occasionally arriving after long intervals in a new 

 and isolated district, and having to compete with new 

 associates, will be eminently liable to modification, and 

 will often produce groups of modified descendants. But 

 it by no means follows, that, because in an island nearly 

 all the species of one class are peculiar, those of another 

 class, or of another section of the same class, are pecu- 

 liar ; and this difference seems to depend on the species 

 which do not become modified having immigrated with 

 facility and in a body, so that their mutual relations 

 have not been much disturbed. Thus in the Galapagos 

 Islands nearly every land-bird, but only two out of the 

 eleven marine birds, are peculiar ; and it is obvious that 



