400 GEOGRAPHICAL DISTRIBUTION. Chap. XII. 



pelago, though specifically distinct, to be closely allied 

 to those of the nearest continent, we sometimes see 

 displayed on a small scale, yet in a most interesting 

 manner, within the limits of the same archipelago. 

 Thus the several islands of the Galapagos Archipelago 

 are tenanted, as I have elsewhere shown, in a quite 

 marvellous manner, by very closely related species ; 

 so that the inhabitants of each separate island, though 

 mostly distinct, are related in an incomparably closer 

 degree to each other than to the inhabitants of any 

 other part of the world. And this is just what might 

 have been expected on my view, for the islands are 

 situated so near each other that they would almost 

 certainly receive immigrants from the same original 

 source, or from each other. But this dissimilarity 

 between the endemic inhabitants of the islands may 

 be used as an argument against my views ; for it may 

 be asked, how has it happened in the several islands 

 situated within sight of each other, having the same 

 geological nature, the same height, climate, &c, that 

 many of the immigrants should have been differently 

 modified, though only in a small degree. This long 

 appeared to me a great difficulty : but it arises in 

 chief part from the deeply-seated error of considering 

 the physical conditions of a country as the most im- 

 portant for its inhabitants ; whereas it cannot, I think, 

 be disputed that the nature of the other inhabitants, 

 with which each has to compete, is at least as impor- 

 tant, and generally a far more important element of 

 success. Now if we look to those inhabitants of the 

 Galapagos Archipelago which are found in other parts 

 of the world (laying on one side for the moment the 

 endemic species, which cannot be here fairly included, 

 as we are considering how they have come to be modi- 

 fied since their arrival), we find a considerable amount 



