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. Probably 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 will 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 perennial cardoon or Castile thistle (Cynara 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 fond. 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, the vizcachas cut down every tall plant they can. I have seen whole acres of maize destroyed by them, yet the plants cut down were left untouched. If posts be put into the ground within range of their nightly rambles they will gnaw till they have felled them, unless of a wood hard enough to resist their chisel-like incisors. The strongest instinct of this animal is to clear the ground thoroughly about its burrows; and it is this destructive habit that makes it necessary for cultivators of the soil to destroy all the vizcachas in or near their fields. On the uninhabited pampas, where the long grasses grow, I have often admired the vizcachera; for it is there the centre of a clean space, often of half an acre in extent, on which there is an even close-shaven turf: this clearing is surrounded by the usual rough growth of herbs and giant grasses. In such situations this habit of clearing the ground is eminently advantageous to them, as it affords them a comparatively safe spot to feed and disport themselves on, and over which they can fly to their burrows without meeting any obstruction, on the slightest alarm.