GEOGRAPHICAL DISTRIBUTION OF ORGANIC BEINGS. 125 



commencement of the last Glacial period, when the Ant- 

 arctic lands, now covered with ice, supported a highly 

 peculiar and isolated flora. It may be suspected that, be- 

 fore this flora was exterminated during the last Glacial 

 epoch, a few forms had been already widely dispersed to 

 various points of the southern hemisphere by occasional 

 means of transport, and by the aid, as halting-places, of 

 now sunken islands. Thus the southern shores of Amer- 

 ica, Australia, and New Zealand, may have become slight- 

 ly tinted by the same peculiar forms of life. 



IDENTITY OF THE SPECIES OF ISLANDS WITH THOSE OF 

 THE MAINLAND EXPLAINED ONLY BY THIS THEORY. 



Ori<nn of The most striking and important fact for 



Species, U s is the affinity of the species which inhabit 

 page 0t islands to those of the nearest mainland, with- 

 out being actually the same. Numerous instances could 

 be given. The Galapagos Archipelago, situated under 

 the equator, lies at the distance of between five hundred 

 and six hundred miles from the shores of South America. 

 Here almost every product of the land and of the water 

 bears the unmistakable stamp of the American Continent. 

 There are twenty-six land-birds ; of these, twenty-one or 

 perhaps twenty-three are ranked as distinct species, and 

 would commonly be assumed to have been here created ; 

 yet the close affinity of most of these birds to American 

 species is manifest in every character, in their habits, 

 gestures, and tones of voice. So it is with the other ani- 

 mals, and with a large proportion of the plants, as shown 

 by Dr. Hooker in his admirable Flora of this archipelago. 

 The naturalist, looking at the inhabitants of these vol- 

 canic islands in the Pacific, distant several hundred miles 

 from the continent, feels that he is standing on American 



