Galapagos Travel Blog

I believe it is well ascertained that the bladder of the frog acts
as a reservoir for the moisture necessary to its existence: such
seems to be the case with the tortoise. For some time after a visit
to the springs, their urinary bladders are distended with fluid,
which is said gradually to decrease in volume, and to become less
pure. The inhabitants, when walking in the lower district, and
overcome with thirst, often take advantage of this circumstance,
and drink the contents of the bladder if full: in one I saw killed,
the fluid was quite limpid, and had only a very slightly bitter
taste. The inhabitants, however, always first drink the water in
the pericardium, which is described as being best.

We will now turn to the order of reptiles, which gives the most
striking character to the zoology of these islands. The species are
not numerous, but the numbers of individuals of each species are
extraordinarily great. There is one small lizard belonging to a
South American genus, and two species (and probably more) of the
Amblyrhynchus--a genus confined to the Galapagos Islands. There is
one snake which is numerous; it is identical, as I am informed by
M. Bibron, with the Psammophis Temminckii from Chile. (17/2. This
is stated by Dr. Gunther "Zoological Society" January 24, 1859, to
be a peculiar species, not known to inhabit any other country.) Of
sea-turtle I believe there are more than one species, and of
tortoises there are, as we shall presently show, two or three
species or races. Of toads and frogs there are none: I was
surprised at this, considering how well suited for them the
temperate and damp upper woods appeared to be. It recalled to my
mind the remark made by Bory St. Vincent, namely, that none of this
family are found on any of the volcanic islands in the great
oceans. (17/3. "Voyage aux Quatres Iles d'Afrique." With respect to
the Sandwich Islands see Tyerman and Bennett's "Journal" volume 1
page 434. For Mauritius see "Voyage par un Officier" etc. Part 1
page 170. There are no frogs in the Canary Islands, Webb et
Berthelot "Hist. Nat. des Iles Canaries." I saw none at St. Jago in
the Cape de Verds. There are none at St. Helena.) As far as I can
ascertain from various works, this seems to hold good throughout
the Pacific, and even in the large islands of the Sandwich
archipelago. Mauritius offers an apparent exception, where I saw
the Rana Mascariensis in abundance: this frog is said now to
inhabit the Seychelles, Madagascar, and Bourbon; but on the other
hand, Du Bois, in his voyage in 1669, states that there were no
reptiles in Bourbon except tortoises; and the Officier du Roi
asserts that before 1768 it had been attempted, without success, to
introduce frogs into Mauritius--I presume for the purpose of
eating: hence it may be well doubted whether this frog is an
aboriginal of these islands. The absence of the frog family in the
oceanic islands is the more remarkable, when contrasted with the
case of lizards, which swarm on most of the smallest islands. May
this difference not be caused by the greater facility with which
the eggs of lizards, protected by calcareous shells, might be
transported through salt-water, than could the slimy spawn of
frogs?