subdued; nature's silence has infected them, and they have become silent
by habit. This is not the case with aquatic species, which are nearly
all migrants from noisier regions, and mass themselves in lagoons and
marshes, where they are all loquacious together. It is also noteworthy
that the subdued bird-voices, some of which are exceedingly sweet and
expressive, and the notes of many of the insects and batrachians have a
great resemblance, and seem to be in accord with the aeolian tones of
the wind in reeds and grasses: a stranger to the pampas, even a
naturalist accustomed to a different fauna, will often find it hard to
distinguish between bird, frog, and insect voices.

The mammalia is poor in species, and with the single exception of the
well-known vizcacha (Lagostomus trichodactylus), there is not one of
which it can truly be said that it is in any special way the product of
the pampas, or, in other words, that its instincts are better suited to
the conditions of the pampas than to those of other districts. As a
fact, this large rodent inhabits a vast extent of country, north, west,
and south of the true pampas, but nowhere is he so thoroughly on his
native heath as on the great grassy plain. There, to some extent, he
even makes his own conditions, like the beaver. He lives in a small
community of twenty or thirty members, in a village of deep-chambered
burrows, all with their pit-like entrances closely grouped together; and
as the village endures for ever, or for an indefinite time, the earth
constantly being brought up forms a mound thirty or forty feet in
diameter; and this protects the habitation from floods on low or level
ground. Again, he is not swift of foot, and all rapacious beasts are his
enemies; he also loves to feed on tender succulent herbs and grasses, to
seek for which he would have to go far afield among the giant grass,
where his watchful foes are lying in wait to seize him; he saves himself
from this danger by making a clearing all round his abode, on which a