292 The Naturalist in La Plata. 



open pampas. Other burrowing species seem 

 always to fix upon some spot where there is a bank 

 or a sudden depression in the soil, or where there 

 is rank herbage, or a bush or tree, about the roots 

 of which to begin their kennel. They are averse 

 to commence digging on a clear level surface, 

 either because it is not easy for them where they 

 have nothing to rest their foreheads against while 

 scratching, or because they possess a wary instinct 

 that impels them to place the body in concealment 

 whilst working on the surface, thus securing the 

 concealment of the burrow after it is made. 

 Certain it is that where large hedges have been 

 planted on the pampas, multitudes of opossums, 

 weasels, skunks, armadillos, &c., come and make 

 their burrows beneath them ; and where there are 

 no hedges or trees, all these species make their 

 kennels under bushes of the perennial thistle, or 

 where there is a shelter of some kind. The vizcacha, 

 on the contrary, chooses an open level spot, the 

 cleanest he can find to burrow on. The first thing 

 that strikes the observer when viewing the vizca- 

 chera closely is the enormous size of the entrance 

 of the burrows, or, at least, of several of the central 

 ones in the mound ; for there are usually several 

 smaller outside burrows. The pit-like opening to 

 some of these principal burrows is often four to six 

 feet across the mouth, and sometimes deep enough 

 for a tall man to stand up waist-deep in. How 

 these large entrances can be made on a level surface 

 may be seen when the first burrow or burrows of 

 an incipient vizcachera are formed. It is not 

 possible to tell what induces a vizcacha to be the 



