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 two sets were
mingled together) all belonged to the two other species:
hence we may feel almost sure that these islands possess
their respective species of these two sub-groups. In land-
shells this law of distribution does not appear to hold good.
In my very small collection of insects, Mr. Waterhouse
remarks, that of those which were ticketed with their locality,
not one was common to any two of the islands.
If we now turn to the Flora, we shall find the aboriginal
plants of the different islands wonderfully different.
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