Derby.] ^b [Feb. 21, 



tions (the source of the Purus is according to Chandless at an elevation 

 of only 1,088 feet above the level of the sea), and, as Chandless has already 

 pointed out, flow in their upper courses in a general easterly direction, as 

 if directed by an imperceptible slope from the Ancles. 



In the Lower Amazonas region, the mountains of Guiana are compara- 

 tively near to the river, and, in consequence, the northern tributaries are 

 small and flow directly towards the main river, with a slight deflection 

 towards the east. On the southern side, on the contrary, the great plateau 

 of central Brazil extends from near the Amazonas to the headwaters of the 

 Paraguay and the mountains of Goyaz. The great tributaries, Tapajos, 

 Xingu and Tocantins, traverse this plateau in a northerly direction, and 

 descend to the level of the Amazonas by a steep incline that commences a 

 short distance above their mouths. I have purposely omitted to mention 

 the Madeira, because this river is related to all three of the sections of the 

 basin. One of its tributaries, the Guapore, rises in the highest part of the 

 central plateau of Brazil, and appears to flow along a margin of that pla- 

 teau (the so-called Cordilheira de Pareeis), until it joins the Mamore which, 

 like theBeni and Madre de Deus, descends from the high Andes of Bolivia, 

 circling round the great eastern projection of the Andes, in the district of 

 Santa Cruz de la Sierra. The lower Madeira, which forms the division 

 between the regions of the Solimoes and the lower Amazonas, flows north- 

 easterly, subparallel with the great features of eastern Brazil, viz : the 

 mountain chains of the coast and of Minas Geraes, and the valleys of the 

 upper Sao Francisco and upper Parana. Farther on I shall have to speak 

 of the significance of this fact. 



Let us now consider in greater detail, the physical and geological fea- 

 tures of the Lower Amazonas region, the immediate subject of this article. 

 What most impresses the traveler on the Amazonas, after the enormous 

 extension, width and volume of the river, the labyrinth of its side channels 

 and the richness of its flora, is the great extent of the varzea or flood-plain 

 that, monotonous as the sea, accompanies the river in a broad belt on each 

 side, from the mouth to the foot of the Andes. Being generally well 

 wooded, the forest gives this flood-plain a false appearance of dry land, 

 and the traveler is very liable to be deceived regarding its true character 

 and extent. To form a true estimate of its importance, it is necessary to 

 ascend one of the few eminences which occur along the margin of the 

 river, as those of Monte Alegre, Santarem and Obydos. From these ele- 

 vations there is seen a great marshy plain, almost on a level with the river, 

 diversified with lakes and island-like groups of trees, and intersected by 

 numerous anastomosing lateral canals, furos or parand-merins, which plain 

 extends for many miles to the highlands of the opposite side, visible in the 

 distant horizon. In this vast plain, the river, great as it is, appears a nar- 

 row ribbon of water, almost lost in the immensity of its ancient bed, for 

 the varzea can only be considered ay a portion, which has been rilled up, 

 of the original bed of the river, or, rather, of the estuary which preceded 

 the riverine condition. In this great depression, the river curves from side 



