420 
GALAPAGOS ARCHIPELAGO 
CHAP. 
the case. It is the fate of most voyagers, no sooner to 
discover what is most interesting in any locality, 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 1 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 
1 Voyage in the US. ship Essex, vol. i. p. 215. 
