THE LIFE OF MAMMALS 
are enemies, but the viscachas are plucky in defending them- 
selves, and ‘“‘will attempt to rescue their friends if attacked by 
a weasel or a peccary, and to disinter those covered up in their 
burrows by man.” The under surface of the viscacha’s up- 
curled tail is padded with a thick, naked, horny skin; ‘‘and 
when the animal performs the curious sportive antics in which 
it occasionally indulges, it gives rapid, loud-sounding blows on 
the ground with this part of the tail.” The pelt is of no value, 
and the flesh is not well liked, though equal or superior to that 
of the hare. 
South Amcrica is the principal home of the porcupine group, 
and that it has always been so is shown by the abundance of 
their remains in the rocks there, carrying their history back 
far into the Tertiary period. The bones of one species, found 
in the Lower Pampas formations, indicate an animal closely 
related to the modern viscacha, but as big as an ox! It is not 
surprising then to find many existing relatives in that conti- 
nent, — agoutis, pacas, capybaras, cavies, and so forth. 
One of the best known of these in former times, when it was 
extremely numerous all over Argentina, was the tall Patagonian 
cavy or mara, which Mr. Darwin called ‘“aguti,” 
and which had the singularity of not being noc- 
turnal, but of wandering and feeding by day, enjoying the 
hottest sunshine. The true agoutis, as we now use the term, 
are forest-loving animals ranging from the borders of the pam- 
pas northward. They are odd, golden-brown little creatures, 
with squirrel-like heads, high round haunches, a mere excuse 
for a tail, and slim legs with practically only three toes on the 
feet, and these armed with hooflike claws, so that, excepting 
its head, the agouti looks like a sleek little pig. 
Agoutis. 
“They are mainly nocturnal, remaining concealed during the day in 
hollow trees, or in cavities or burrows among their roots;... Their move- 
ments are extremely active and graceful. When going slowly they advance 
at a kind of trot, but when running their pace takes the form of a series of 
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