These two species of Amblyrhynchus agree, as I have already stated, in
their general structure, and in many of their habits. Neither have
that rapid movement, so characteristic of the genera Lacerta and
Iguana. They are both herbivorous, although the kind of vegetation on
which they feed is so very different. Mr. Bell has given the name to
the genus from the shortness of the snout: indeed, the form of the
mouth may almost be compared to that of the tortoise: one is led to
suppose that this is an adaptation to their herbivorous appetites. It
is very interesting thus to find a well-characterized genus, having its
marine and terrestrial species, belonging to so confined a portion of
the world. The aquatic species is by far the most remarkable, because
it is the only existing lizard which lives on marine vegetable
productions. As I at first observed, these islands are not so
remarkable for the number of the species of reptiles, as for that of
the individuals, when we remember the well-beaten paths made by the
thousands of huge tortoises--the many turtles--the great warrens of the
terrestrial Amblyrhynchus--and the groups of the marine species basking
on the coast-rocks of every island--we must admit that there is no
other quarter of the world where this Order replaces the herbivorous
mammalia in so extraordinary a manner. The geologist on hearing this
will probably refer back in his mind to the Secondary epochs, when
lizards, some herbivorous, some carnivorous, and of dimensions
comparable only with our existing whales, swarmed on the land and in
the sea. It is, therefore, worthy of his observation, that this
archipelago, instead of possessing a humid climate and rank vegetation,
cannot be considered otherwise than extremely arid, and, for an
equatorial region, remarkably temperate.
To finish with the zoology: the fifteen kinds of sea-fish which I
procured here are all new species; they belong to twelve genera, all
widely distributed, with the exception of Prionotus, of which the four
previously known species live on the eastern side of America. Of
land-shells I collected sixteen kinds (and two marked varieties), of
which, with the exception of one Helix found at Tahiti, all are
peculiar to this archipelago: a single fresh-water shell (Paludina) is
common to Tahiti and Van Diemen's Land. Mr. Cuming, before our voyage
procured here ninety species of sea-shells, and this does not include
several species not yet specifically examined, of Trochus, Turbo,
Monodonta, and Nassa. He has been kind enough to give me the following
interesting results: Of the ninety shells, no less than forty-seven are
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