REVIEWS. 
119 
The tributary streams, watering this vast territory, are numerous, and 
present to the naturalist some very remarkable differences in the character 
of the vegetation on their banks, the animals that inhabit them, and even 
the very colour of their water. This last point of difference is so remarkable 
as to enable them to be classed in three great groups —the white-water 
rivers , the blue-water rivers , and the blacJc-water rivers. To the first of 
these divisions the main stream of the Amazon itself belongs; and it would 
appear that its colour (a pale yellowish olive) is not entirely dependent on 
free, earthy matter, but rather on some colouring material, held in solution. 
All the rivers that rise in the mountains of Brazil belong to the blue or 
clear water class; of these the principal are the Tocatiiis, the Xingu, and 
the Tapajoz. Above the Madeira the black-water rivers are first met with. 
Of these the Kio Negro is the most celebrated; it rises in 2° 30’ N. lat., 
where its waters are much blacker than in the lower part of its course. 
The peculiar colour of these rivers would appear to be produced by the 
solution of decaying leaves, roots, and other vegetable matter. 
The examination of the geological peculiarities of so vast an area, and 
the comparative rarity of natural sections falling under the observations of 
a single individual, is of but little value. It is, however, remarkable that Mr. 
Wallace was unable to find any trace of fossil remains, which prevents any 
geological age being assigned to the various beds of rock which occur. To 
the botanist, however, the riches of this district are most attractive. Mr. 
Wallace thus speaks of the vegetation:— 
“ 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 Parnaiba, 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 2,600 miles, will have passed through the 
centre of it, dividing it into two nearly equal portions. 
“ For the first thousand miles, or as far as long. 56° W., the width of the forest, 
from north to south, is about 400 miles ; it then stretches out both to the north and 
south, so that in long. 67 c W. it extends from 7° N., on the banks of the Orinooko, 
to 18 oS., on the northern slope of the Andes of Bolivia, a distance of more than 
seventeen hundred miles. Prom a point about sixty miles south-east of Tabatinga, 
a circle may he drawn of 1,100 miles in diameter, the whole area of which will be 
virgin forest.” 
Forests our author regards as the characteristic of the New World, as 
