wedge-shaped tail admirably fitting into the deep-cut shell side by
side; and the _quirquincho_ (Dasypus minutus), all inhabit the pampa,
are diurnal, and feed exclusively on insects, chiefly ants. Wherever the
country becomes settled, these three disappear, owing to the dulness of
their senses, especially that of sight, and to the diurnal habit, which
was an advantage to them, and enabled them to survive when rapacious
animals, which are mostly nocturnal, were their only enemies. The
fourth, and most important, is the hairy armadillo, with habits which
are in strange contrast to those of its perishing congeners, and which
seem to mock many hard-and-fast rules concerning animal life. It is
omnivorous, and will thrive on anything from grass to flesh, found dead
and in all stages of decay, or captured by means of its own strategy.
Furthermore, its habits change to suit its conditions: thus, where
nocturnal carnivores are its enemies, it is diurnal; but where man
appears as a chief persecutor, it becomes nocturnal. It is much hunted
for its flesh, dogs being trained for the purpose; yet it actually
becomes more abundant as population increases in any district; and, if
versatility in habits or adaptiveness can be taken as a measure of
intelligence, this poor armadillo, a survival of the past, so old on the
earth as to have existed contemporaneously with the giant glyptodon, is
the superior of the large-brained cats and canines.

To finish with the mammalia, there are two interesting opossums, both of
the genus Didelphys, but in habits as wide apart as cat from otter. One
of these marsupials appears so much at home on the plains that I almost
regret having said that the vizcacha alone gives us the idea of being in
its habits the _product_ of the pampas. This animal--Didelphys
crassicaudata--has a long slender, wedge-, shaped head and body,
admirably adapted for pushing through the thick grass and rushes; for it
is both terrestrial and aquatic, therefore well suited to inhabit low,