Perhaps no country in the world contains such an amount of vegetable matter on its surface as the valley of the Amazon. Its entire extent, with the exception of some very small portions, is covered with one dense and lofty primeval forest, the most extensive and unbroken which exists upon the earth. It is the great feature of the country,—that which at once stamps it as a unique and peculiar region. It is not here as on the coasts of southern Brazil, or on the shores of the Pacific, where a few days' journey suffices to carry us beyond the forest district, and into the parched plains and rocky serras of the interior. Here we may travel for weeks and months inland, in any direction, and find scarcely an acre of ground unoccupied by trees. It is far up in the interior, where the great mass of this mighty forest is found; not on the lower part of the river, near the coast, as is generally supposed.

A line from the mouth of the river Parnaíba, in long. 41° 30′ W., drawn due west towards Guayaquil, will cut the boundary of the great forest in long. 78° 30′, and, for the whole distance of about 2600 miles, will have passed through the centre of it, dividing it into two nearly equal portions.