60 The Naturalist in La Plata. 
plantation adjoining my house I found, during the 
season, no fewer than seventeen nests. 
The season was also favourable for mice; that is, 
of course, favourable for the time being, unfavour- 
able in the long run, since the short-lived, undue 
preponderance of a species is invariably followed 
by a long period of undue depression. These pro- 
lific little creatures were soon so abundant that the 
dogs subsisted almost exclusively on them; the 
fowls also, from incessantly pursuing and killing 
them, became quite rapacious in their manner; 
whilst the sulphur tyrant-birds (Pitangus) and the 
Guira cuckoos preyed on nothing but mice. 
The domestic cats, as they invariably do in such 
plentiful seasons, absented themselves from the 
house, assuming all the habits of their wild con- 
geners, and slinking from the sight of man—even of 
a former fireside companion—with a shy secrecy in 
their motions, an apparent affectation of fear, almost 
ludicrous to see. Foxes, weasels, and opossums 
fared sumptuously. Even for the common armadillo 
(Dasypus villosus) it was a season of affluence, for 
this creature is very adroit in capturing mice. This 
fact might seem surprising to anyone who marks 
the uncouth figure, toothless gums, and the motions 
—anything but light and graceful—of the armadillo ; 
and perhaps fancying that, to be a dexterous mouser, 
an animal should bear some resemblance in habit.; 
and structure to the felide. But animals, like men, 
are compelled to adapt themselves to their surround- 
ings ; new habits are acquired, and the exact co- 
relation between habit and structure is seldom 
maintained. 
