hey become tinged with yellow, and they often use it to render their
papagaios more variegated.

THE GYMNOTUS.

On the Amazonian waters is found the carapus, called by the Brazilians
sarapo, belonging to the genus Gymnotus; though far smaller than the
electric gymnotus. They are very numerous, and the most lively of the
whole group. Their motions are winding and rapid, like those of the
eel; but yet different, inasmuch as they do not glide quickly forward,
but turn frequent somersaults, and constantly change their direction.

LOCALISATION OF FISH.

The researches of Professor Agassiz prove that the localisation of
species of fish in these waters is peculiarly distinct and permanent,
their migrations being very limited--consisting chiefly in removing from
shallow to deeper waters, and from these to shallow again, at those
seasons when the range of the shore in the same water-basin is affected
by the rise and fall of the river. Thus, the fishes found at the bottom
of a lake covering, perhaps, a square mile in extent when the waters are
lowest, will appear near the shores of the same lake when, at the season
of high-water, it extends over a much wider area. In the same way,
fishes which gather near the mouth of a rivulet at the time of
low-water, will be found as high as its origin at the period of
high-water; and those which inhabit the larger igarapes on the sides of
the Amazon, when they are swollen by the rise of the river, may be found
in the Amazon itself when the stream is low. There is not a single fish
known to ascend from the sea to the higher courses of the Amazon at
certain seasons, and to return regularly to the ocean.

The striking limitation of species within different areas does not,
however, exclude the presence of certain kinds of fish simultaneously
throughout the whole Amazonian basin. The piraracu, for instance, is
found everywhere from Peru to Para; and so are a few other species more
or less extensively distributed over what may be considered distinct
ichthyological fauna. But these wide-spread species are not migratory.
They have normally and permanently a wide range--just as some
terrestrial animals have an almost cosmopolitan character--while others
are circumscribed within comparatively narrow limits.

Surprising indeed is the variety of species of fishes contained in the
Amazonian basin. Professor Agassiz, during his expedition, collected
nearly two thousand, "for the most part," a