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 
