CHAPTER XxX. 
BIOGRAPHY OF THE VIZCACHA, 
(Lagostomus Trichodactylus.) 
THE vizcacha is perhaps the most characteristic of 
the South American Rodentia,’ while its habits, in 
some respects, are more interesting than those of 
any other rodent known: it is, moreover, the most 
common mammal we have on the pampas; and al] 
these considerations have induced me to write a 
very full account of its customs. It is necessary to 
add that since the following pages were written at 
my home on the pampas a great war of extermina- 
tion has been waged against this animal by the 
" © According to Mr. Waterhouse, of all rodents the vizcacha 
is most nearly related to marsupials ; but in the points in which 
it approaches this order its relations are general, that is, not to 
any one marsupial species more than to another. As these points 
of affinity are believed to be real and net merely adaptive, they 
must be due in accordance with our view to inheritance from a 
common progenitor. Therefore we must suppose either that all 
rodents, including the vizcacha, branched off from some ancient 
marsupial, which will naturally have been more or less  inter- 
mediate in character with respect to all existing marsupials; or, 
that both rodents and marsupials branched off from a common 
progenitor... . On either view we must suppose that the 
vizecacha has retained, by inheritance, more of the characters of 
its ancient progenitor than have other rodents.”—Darwin ; Origin 
of Species. 
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