Although We Could
Nowhere Find, During Our Whole Visit, A Single Drop Of Fresh
Water, Yet Some Must Exist; For
By an odd chance I found on
the surface of the salt water, near the head of the bay, a
Colymbetes not quite dead, which must have lived in some
not far distant pool. Three other insects (a Cincindela, like
hybrida, a Cymindis, and a Harpalus, which all live on muddy
flats occasionally overflowed by the sea), and one other
found dead on the plain, complete the list of the beetles. A
good-sized fly (Tabanus) was extremely numerous, and tormented
us by its painful bite. The common horsefly, which
is so troublesome in the shady lanes of England, belongs to
this same genus. We here have the puzzle that so frequently
occurs in the case of musquitoes - on the blood of what
animals do these insects commonly feed? The guanaco is
nearly the only warm-blooded quadruped, and it is found in
quite inconsiderable numbers compared with the multitude
of flies.
The geology of Patagonia is interesting. Differently from
Europe, where the tertiary formations appear to have accumulated
in bays, here along hundreds of miles of coast we
have one great deposit, including many tertiary shells, all
apparently extinct. The most common shell is a massive
gigantic oyster, sometimes even a foot in diameter. These
beds are covered by others of a peculiar soft white stone,
including much gypsum, and resembling chalk, but really of
a pumiceous nature. It is highly remarkable, from being
composed, to at least one-tenth of its bulk, of Infusoria.
Professor Ehrenberg has already ascertained in it thirty
oceanic forms.
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