The Desert Pampas. 17 
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. Further- 
more, its habits change to suitits conditions : thus, 
where nocturnal carnivores are its enemies, it is 
diurnal; but where man appears as a chief perse- 
cutor, 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 intelli- 
gence, this poor armadillo, a survival of the past, so 
old on the earth as to have existed contempora- 
neously 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— 
