The mammalia is poor in species, and with the single exception of the well-known vizcacha (Lagostomus trichodactylus), there is not one of which 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 brought 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 animals feed and have their evening pastimes in comparative security: for when an enemy approaches, 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. How marvellous a thing it seems that the two species of mammalians--the beaver and the vizcacha--that most nearly simulate men's intelligent actions in their social organizing instincts, and their habitations, which are made to endure, should belong to an order so low down as the Rodents! And in the case of the latter species, it adds to the marvel when we find that the vizcacha, according to Water-house, is the lowest of the order in its marsupial affinities. The vizcacha is the most common rodent on the pampas, and the Rodent order is represented by the largest number of species. The finest is the so-called Patagonian hare--Dolichotis patagonica--a beautiful animal twice as large as a hare, with ears shorter and more rounded, and legs relatively much longer. The fur is grey and chestnut brown. It is diurnal in its habits, lives in kennels, and is usually met with in pairs, or small flocks. It is better suited to a sterile country like Patagonia than to the grassy humid plain; nevertheless it was found throughout the whole of the pampas; but in a country where the wisdom of a Sir William Harcourt was never needed to slip the leash, this king of the Rodentia is now nearly extinct.