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 [5] 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. Unfortunately 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 representatives of Geospiza, it may
help to explain the singularly large number of the species of this
sub-group in this one small archipelago, and as a probable consequence
of their numbers, the perfectly graduated series in the size of their
beaks. Two species of the sub-group Cactornis, and two of the
Camarhynchus, were procured in the archipelago; and of the numerous
specimens of these two sub-groups shot by four collectors at James
Island, all were found to belong to one species of each; whereas the
numerous specimens shot either on Chatham or Charles Island (for the
371