I cannot speak of this Serra without alluding to the great beauty and extraordinary extent of the view to be obtained from it. Indeed, it was here that for the first time the geography of the country presented itself to my mind as a living reality in all its completeness. Insignificant as is its actual height, the Serra of Ereré commands a wider prospect than is to be had from many a more imposing mountain; for the surrounding plain, covered with forests and ploughed by countless rivers, stretches away for hundreds of leagues in every direction, without any object to obstruct the view. Standing on the brow of the Serra, with the numerous lakes intersecting the lowlands at its base, you look across the valley of the Amazons, as far as the eye can reach, and through its centre you follow for miles on either side the broad flood of the great river, carrying its yellow waters to the sea. As I stood there, panoramas from the Swiss mountains came up to my memory, and I fancied myself on the Alps, looking across the plain of Switzerland instead of the bed of the Amazons; the distant line of the Santarem hills on the southern bank of the river, and lower than the northern chain, representing the Jura range. As if to complete the comparison, Alpine lichens were growing among the cacti and palms, and a crust of Arctic cryptogamous growth covered rocks, between which sprang tropical flowers. On the northern flank of this Serra I found the only genuine erratic boulders I have seen in the whole length of the Amazonian Valley from Pará to the frontier of Peru, though there are many detached masses of rock, as, for instance, at Pedreira, near the junction of the Rio Negro and Rio Branco, which might be mistaken for them, but are due to the decomposition of the rocks in place. The boulders of Ereré are entirely distinct from the rock of the Serra, and consist of masses of compact hornblende.