420 GALAPAGOS ARCHIPELAGO chap. 



the case. It is the fate of most voyagers, no sooner to 

 discover what is most interesting in any locahty, than they are 

 hurried from it ; but I ought, perhaps, to be thankful that I 

 obtained sufficient materials to establish this most remarkable 

 fact in the distribution of organic beings. 



The inhabitants, as I have said, state that they can 

 distinguish the tortoises from the different islands ; and that 

 they differ not only in size, but in other characters. Captain 

 Porter has described ^ those from Charles and from the nearest 

 island to it, namely Hood Island, as having their shells in 

 front thick and turned up like a Spanish saddle, whilst the 

 tortoises from James Island are rounder, blacker, and have a 

 better taste when cooked. M. Bibron, moreover, informs me 

 that he has seen what he considers two distinct species of 

 tortoise from the Galapagos, but he does not know from which 

 islands. The specimens that I brought from three islands 

 were young ones ; and probably owing to this cause, neither 

 Mr. Gray nor myself could find in them any specific differences. 

 I have remarked that the marine Amblyrhynchus was larger 

 at Albemarle Island than elsewhere ; and M. Bibron informs 

 me that he has seen two distinct aquatic species of this 

 genus ; so that the different islands probably have their 

 representative species or races of the Amblyrhynchus, as well 

 as of the tortoise. My attention was first thoroughly aroused 

 by comparing together the numerous specimens, shot by 

 myself and several other parties on board, of the mocking- 

 thrushes, when, to my astonishment, I discovered that all those 

 from Charles Island belonged to one species (Mimus trifasciatus) ; 

 all from Albemarle Island to M. parvulus ; and all from James 

 and Chatham Islands (between which two other islands are 

 situated, as connecting links) belonged to M. melanotis. 

 These two latter species are closely allied, and would by some 

 ornithologists be considered as only well-marked races or 

 varieties ; but the Mimus trifasciatus is very distinct. Un- 

 fortunately most of the specimens of the finch tribe were 

 mingled together ; but I have strong reasons to suspect that 

 some of the species of the sub-group Geospiza are confined to 

 separate islands. If the different islands have their repre- 

 sentatives of Geospiza, it may help to explain the singularly 

 ^ Voyage in the U.S. skip £ssex, vol. i. p. 215. 



