CHAPTER XX. 



BIOGRAPHY OF THE VIZCAGHA. 



{Lagostomus Trichodactylus.) 



The vizcacha is perhaps tlie most characteristic of 

 tlie South American Eodentia,^ 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 all 

 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 ATr. Waterlioiise,.of all rodents tlie 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 not 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 lodents and marsupials branched off from a common 

 progenitor. . . . On either view we must suppose that the 

 vizcacha has retained, by inheritance, more of the characters of 

 its ancient progenitor than have other rodents." — DarwiiV ; Origin 

 of Sjiecies, 



