Pampas, the great plains of South America, stretching from lat. 50° S. in Patagonia northward through the Argentine Republic to the Bolivian frontier, about 27 degrees of latitude, and covering an area of about 600,000 sq. m. The northern portion is occupied by the vast unexplored territory of the Gran Chaco; the southern forms an immense desert interspersed with sand pools; the eastern, extensive plains and marshes, with tracts entirely inundated; while the western border rises gradually into the elevated region of Salta, Tucuman, Santiago, Cordova, and San Luis, in the Argentine Eepublic, and into the Andes proper in Patagonia. The natural features of the northern and northwestern parts are plains of magnificent pasture, dense timber forests, and numerous lagoons and rivers, chief among the last being the Pilcomayo and the Bermejo. The central portion is distinguishable into several subdivisions, differing in climate and products, although under the same parallel. Proceeding westward from Buenos Ayres, the first of these presents for nearly 200 m. an alternate growth of clover and thistles; the next, a covering of long grass and brilliant flowers extending without a weed some 400 m. further westward; the third, reaching to the base of the Andes, one continuous grove of shrubs and small evergreen trees, so evenly set that a horseman may gallop at random between them without inconvenience.

Change of season brings little variation in the aspect of the two regions last referred to ; but in the first remarkable mutations occur. During the winter months the thistles and clover are exceedingly rich and strong, and support countless herds of wild cattle. On the approach of spring the clover disappears, and nothing is distinguishable save an immense forest of giant thistles, so closely set and so strong as to form an impenetrable barrier. In summer the thistles give place to a new and luxurious growth of clover. Numerous rivers traverse the central and southern parts, but the only absolutely perennial stream is the Rio Negro, which forms the boundary line with Patagonia. The Andine regions abound in guanacos, llamas, and vicu-fias; deer, wild hogs, and armadillos are everywhere found; ostriches are plenty; and the rodent tocutuco and vizcacha render travel dangerous from their burrowings.