10 The Naturalist in La Plata. 



wliicli it can truly be said that it is in any special 

 way the product of the pampas, or, in other words, 

 that its instincts are better suited to the conditions 

 of the pampas than to those of other districts. As 

 a fact, this large rodent inhabits a vast extent of 

 country, north, west, and south of the true pampas, 

 but nowhere is he so thoroughly on his native heath 

 as on the great grassy plain. There, to some extent, 

 he even makes his own conditions, like the beaver. 

 He lives in a small community of twenty or thirty 

 members, in a village of deep-chambered burrows, 

 all with their pit-like entrances closely grouped 

 together ; and as the village endures for ever, or for 

 an indefinite time, the earth constantly being bi'ought 

 up forms a mound thirty or forty feet in diameter ; 

 and this protects the habitation from floods on low 

 or level ground. Again, he is not swift of foot, and 

 all rapacious beasts are his enemies ; he also loves 

 to feed on tender succulent herbs and grasses, to 

 seek for which he would have to go far afield among 

 the giant grass, where his watchful foes are lying 

 in wait to seize him; he saves himself from this 

 danger by making a clearing all round his abode, 

 on which a smooth turf is formed ; and here the 

 aniihals feed and have their evening pastimes in 

 comparative security : for when an enemy ap- 

 proaches, he is easily seen ; the note of alarm is 

 sounded, and the whole company scuttles away to 

 their refuge. In districts having a different soil 

 and vegetation, as in Patagonia, the vizcachas' 

 curious, unique instincts are of no special advantage, 

 which makes it seem probable that they have been 

 formed on the pampas. 



