XVII DISTRIBUTION OF THE ORGANIC BEINGS 423 



genera, as does to a certain extent hold good ; for, to give 

 one instance, a large berry-bearing tree at James Island has 

 no representative species in Charles Island. But it is the 

 circumstance, that several of the islands possess their own 

 species of the tortoise, mocking-thrush, finches, and numerous 

 plants, these species having the same general habits, occupying 

 analogous situations, and obviously filling the same place in 

 the natural economy of this archipelago, that strikes me with 

 wonder. It may be suspected that some of these representative 

 species, at least in the case of the tortoise and of some of the 

 birds, may hereafter prove to be only well-marked races ; but 

 this would be of equally great interest to the philosophical 

 naturalist. I have said that most of the islands are in sight 

 of each other : I may specify that Charles Island is fifty miles 

 from the nearest part of Chatham Island, and thirty-three 

 miles from the nearest part of Albemarle Island. Chatham 

 Island is sixty miles from the nearest part of James Island, 

 but there are two intermediate islands between them which 

 were not visited by me. James Island is only ten miles from 

 the nearest part of Albemarle Island, but the two points where 

 the collections were made are thirty-two miles apart. I must 

 repeat, that neither the nature of the soil, nor height of the 

 land, nor the climate, nor the general character of the associated 

 beings, and therefore their action one on another, can differ 

 much in the different islands. If there be any sensible 

 difference in their climates, it must be between the windward 

 group (namely Charles and Chatham Islands), and that to 

 leeward ; but there seems to be no corresponding difference 

 in the productions of these two halves of the archipelago. 



The only light which I can throw on this remarkable 

 difference in the inhabitants of the different islands, is, that 

 very strong currents of the sea running in a westerly and 

 W.N.W. direction must separate, as far as transportal by the 

 sea is concerned, the southern islands from the northern ones ; 

 and between these northern islands a strong N.W. current was 

 observed, which must effectually separate James and Albemarle 

 Islands. As the archipelago is free to a most remarkable 

 degree from gales of wind, neither the birds, insects, nor lighter 

 seeds, would be blown from island to island. And lastly, the 

 profound depth of the ocean between the islands, and their 



