that Captain Wood, in his voyage in 1670, talks of them as
being numerous there. What cause can have altered, in a
wide, uninhabited, and rarely-visited country, the range of
an animal like this? It appears also, from the number shot
by Captain Wood in one day at Port Desire, that they must
have been considerably more abundant there formerly than
at present. Where the Bizcacha lives and makes its burrows,
the Agouti uses them; but where, as at Bahia Blanca, the
Bizcacha is not found, the Agouti burrows for itself. The
same thing occurs with the little owl of the Pampas (Athene
cunicularia), which has so often been described as standing
like a sentinel at the mouth of the burrows; for in Banda
Oriental, owing to the absence of the Bizcacha, it is obliged
to hollow out its own habitation.

The next morning, as we approached the Rio Colorado,
the appearance of the country changed; we soon came on a
plain covered with turf, which, from its flowers, tall clover,
and little owls, resembled the Pampas. We passed also a
muddy swamp of considerable extent, which in summer dries,
and becomes incrusted with various salts; and hence is called
a salitral. It was covered by low succulent plants, of the
same kind with those growing on the sea-shore. The Colorado,
at the pass where we crossed it, is only about sixty
yards wide; generally it must be nearly double that width.
Its course is very tortuous, being marked by willow-trees
and beds of reeds: in a direct line the distance to the mouth
of the river is said to be nine leagues, but by water
twenty-five. We were delayed crossing in the canoe by some
immense troops of mares, which were swimming the river in