This line of separation of the waters is important in relation to facilities of intercourse, and to the increase of cultivation and civilisation: more to the north (2°-3° N. lat.), a similar line divides the basin of the Orinoco from that of the Amazons and the Rio Negro. These risings or swellings in the plains (called, by Frontin, terræ tumores) might be regarded as undeveloped systems of mountains, which would have connected two apparently isolated groups (the Sierra Parime and the Brazilian mountains) with the Andes of Timana and Cochabamba. These relations, which have been hitherto but little attended to, are the ground of the division which I have made of South America into three basins; viz. those of the lower Orinoco, of the Amazons, and of the Rio de la Plata. The first and last of these are steppes or prairies; the middle basin, that of the Amazons, between the Sierra Parime and the Brazilian group of mountains, is a forest-covered plain or _Hylæa_. If we wish to trace, in equally few lines, a sketch of the natural features of North America, let us cast our eyes first on the mountain chain which, running from south-east to north-west, at first low and narrow, and increasing both in breadth and height from Panama to Veragua, Guatimala, and Mexico (where it was the seat of a civilisation which preceded the arrival of Europeans), arrests the general equatorial current of the waters of the ocean, and opposes a barrier to the more rapid commercial intercourse of Europe and Western Africa with the eastern parts of Asia. North of the 17th degree of latitude and the celebrated isthmus of Tehuantepec, the mountains, quitting the coast of the Pacific, and following a more direct northerly course, become an inland Cordillera. In North Mexico, the “Crane Mountains” (Sierra de las Grullas) form part of the Rocky Mountain chain. Here rise, to the west, the Columbia and the Rio Colorado of California; and, to the east, the Rio Roxo de Natchitoches, the Candian, the Arkansas, and the Platte or shallow river, a name which has latterly been ignorantly transformed into that of a silver-promising river Plate. Between the sources of these rivers (from N. lat. 37° 20′ to 40° 13′) rise three lofty summits (formed of a granite containing much hornblende and little mica), called Spanish Peak, James’s or Pike’s Peak, and Big Horn or Long’s Peak. (See my Essai Politique sur la Nouvelle Espagne, 2me édit. t. i. pp. 82 and 109.) The elevation of these peaks exceeds that of any of the summits of the Andes of North Mexico, which, indeed, from the 18th and 19th parallels of latitude, or from the group of Orizaba and Popocatepetl (respectively 2717 toises or 17374 English feet, and 2771 toises or 17720 English feet,) to Santa Fé and Taos, never reach the limits of perpetual snow. James Peak, in lat. 38° 40′, is supposed to be 1798 toises, or 11497 English feet; but of this elevation only 1335 toises (8537 English feet) has been measured trigonometrically,