Galapagos Travel Blog

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 unknown
elsewhere--a wonderful fact, considering how widely distributed
sea-shells generally are. Of the forty-three shells found in other
parts of the world, twenty-five inhabit the western coast of
America, and of these eight are distinguishable as varieties; the
remaining eighteen (including one variety) were found by Mr. Cuming
in the Low Archipelago, and some of them also at the Philippines.
This fact of shells from islands in the central parts of the
Pacific occurring here, deserves notice, for not one single
sea-shell is known to be common to the islands of that ocean and to
the west coast of America. The space of open sea running north and
south off the west coast separates two quite distinct conchological
provinces; but at the Galapagos Archipelago we have a
halting-place, where many new forms have been created, and whither
these two great conchological provinces have each sent several
colonists. The American province has also sent here representative
species; for there is a Galapageian species of Monoceros, a genus
only found on the west coast of America; and there are Galapageian
species of Fissurella and Cancellaria, genera common on the west
coast, but not found (as I am informed by Mr. Cuming) in the
central islands of the Pacific. On the other hand, there are
Galapageian species of Oniscia and Stylifer, genera common to the
West Indies and to the Chinese and Indian seas, but not found
either on the west coast of America or in the central Pacific. I
may here add, that after the comparison by Messrs. Cuming and Hinds
of about 2000 shells from the eastern and western coasts of
America, only one single shell was found in common, namely, the
Purpura patula, which inhabits the West Indies, the coast of
Panama, and the Galapagos. We have, therefore, in this quarter of
the world, three great conchological sea-provinces, quite distinct,
though surprisingly near each other, being separated by long north
and south spaces either of land or of open sea.