1:.| DISTRIBUTION OF Tliti ORGANIC BEINGS. 381 



both mundane genera, have respectively six and seven species, none 

 of which have the same species on two islands, with the exception 

 of one Borreria, which does occur on two islands. The species of 

 the Composite arc particularly local ; and Dr. Hooker has furnished 

 me with several other most striking illustrations of the difference 

 of the species on the different islands. He remarks that this law of 

 distribution holds good both with those genera confined to the 

 archipelago, and those distributed in other quarters of the world : 

 in like manner we have seen that the different islands have their 

 proper species of the mundane genus of tortoise, and of the widely 

 distributed American genus of the mocking thrush, as well as of 

 two of the Galapageian sub-groups of finches, and almost certainly 

 of the Galapageiau genus Amblyrhynchus. 



The distribution of the tenants of this archipelago would not bo 

 nearly so wonderful, if, for instance, one island had a mockiog- 

 thrush, and a second island some other quite distinct genus; if 

 one island had its genus of lizard, and a second island another 

 distinct genus, or none whatever ; or if the different islands wero 

 inhabited, not by representative species of the same genera of 

 plants, but by totally different 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 bo suspected that some of these representative species, at 

 least in the case of the tortoise and of some of the birds, may here- 

 after 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 

 Avhich 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 

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



