302 The Naturalist in La Plata. 



its very slow rate of increase, and yet see them in 

 such incalculable numbers. The female has but one 

 litter in the year of two young, sometimes of three. 

 She becomes pregnant late in April, and brings 

 forth in September ; the period of gestation is, I 

 think, rather less than five months. 



The vizcacha is about two years growing. A 

 full-sized male measures to the root of the tail 

 twenty-two inches, and weighs from fourteen to 

 fifteen pounds ; the female is nineteen inches in 

 length, and her greatest weight nine pounds. Pro- 

 bably it is a long-lived, and certainly it is a very hardy 

 animal. Where it has any green substance to eat 

 it never drinks water ; but after a long ,summer 

 drought, when for months it has subsisted on 

 bits of dried thistle-stalks and old withered grass, 

 if a shower falls it Avill come out of its burrows 

 even at noonday and drink eagerly from the pools. 

 It has been erroneously stated that vizcachas 

 subsist on roots. Their food is grass and seeds; 

 but they may also sometimes eat roots, as the 

 ground is occasionally seen scratched up about the 

 burrows. In March, when the stalks of the peren- 

 nial cardoon or Castile thistle (Oynara cardunculus) 

 are dry, the vizcachas fell them by gnawing about 

 their roots, and afterwards tear to pieces the great 

 dry flower-heads to get the seeds imbedded deeply 

 in them, of which they seem very foud. Large 

 patches of thistle are often found served thus, the 

 ground about them literally white with the silvery 

 bristles they have scattered. This cutting down 

 tall plants to get the seeds at the top seems very 

 like an act of pure intelligence; but the fact is, 



