Biography of the Vizcacha. 295 



may be so curved inwards as to form the segment 

 of a circle. Many other forms may also be noticed, 

 but usually they appear to be only modifications of 

 the most common Y-shaped system. 



As I have remarked that its manner of burrowing 

 has peculiarly adapted the vizcacha to the pampas, 

 it may be asked what particular advantage a species 

 that makes a wide-mouthed burrow possesses over 

 those that excavate in the usual way. On a 

 declivity, or at the base of rocks or trees, there 

 would be none; but on the perfectly level and 

 shelterless pampas, the durability of the burrow, a 

 circumstance favourable to the animal's preserva- 

 tion, is owing altogether to its being made in this 

 way, and to several burrows being made together. 

 The two outer trenches diverge so widely from the 

 mouth that half the earth brought out is cast 

 behind instead of before it, thus creating a mound 

 of equal height about the entrance, by which it is 

 secured from water during great rainfalls, while 

 the cattle avoid treading over the great pit-like 

 entrances. But the burrows of the dolichotis, 

 armadillo, and other species, when made on perfectly 

 level ground, are soon trod on and broken in by 

 cattle ; in summer they are choked up with dust 

 and rubbish ; and, the loose earth having all been 

 thrown up together in a heap on one side, there is 

 no barrier to the water which in every great rain- 

 fall flows in and obliterates the kennel, drowning 

 or driving out the tenant. 



I have been minute in describing the habitations 

 of the vizcacha, as I esteem the subject of prime 

 importance in considering the zoology of this 



