1618 THE STORY OF THE UNIVERSE 



developed social instinct, among the two or three 

 mammals which approach man, although only a 

 rodent, and even in this order, according to Water- 

 house, coming very low down by reason of its mar- 

 supial affinities. 



The vizcacha lives in small communities of from 

 twenty to thirty members, in a village of deep- 

 chambered burrows, some twelve or fifteen in num- 

 ber, with large pit-like entrances closely grouped 

 together, and as the vizcachera, as this village is 

 called, endures for an indefinitely long period, the 

 earth which is constantly brought up forms an irreg- 

 ular mound thirty or forty feet in diameter, and from 

 fifteen to thirty inches above the level of the road; 

 this mound serves to protect the dwelling from 

 floods on low ground. A clearing is made all round 

 the abode and all rubbish thrown on the mound ; the 

 vizcachas thus have a smooth turf on which to dis- 

 port themselves, and are freed from the danger of 

 lurking enemies. 



The entire village occupies an area of one hundred 

 to two hundred square feet of ground. The burrows 

 vary greatly in extent; usually in a vizcachera there 

 are several that, at a distance of from four to six feet 

 from the entrance, open into large circular chambers. 

 From these chambers other burrows diverge in all 

 directions, some running horizontally, others oblique- 

 ly downward to a maximum depth of six feet from 

 the surface; some of these galleries communicate 

 with those of other burrows. 



On viewing a vizcachera closely, the first thing that 

 strikes the observer is the enormous size of the 



