i 
THE RAPIDS OF THE MADEIRA AND THE MAMORE. 77 
haskiiij' alligator— tliat we were uumolcsted (luring our stay of a 
lortniglit in the (lomain of these robbers. (In the 1st of September 
^^■e reached at last the confluence of the Mamore and the Gnapoi'e ; 
the former of which has a width of 330 yards at low, and of 550 
yards at high water. 
Though the GuAPORit is considerably' broader than the Mainore (550 
yards at low and 7 60 yards at high water), its volume is less by a third, 
as we found upon careful measurings of its profile and its rapidity.* 
The shores of both these rivers are low, but not exposed to the 
ordinary floods. The clear greenish tinge of the Guaporci is striking, 
while the Mamore is decidedly' y'cllow. The latter, in its lower course, 
has an extraordinary' number of .short, sharp curves, on whose convex 
sides there are uniformly sand-banks, sometimes of considerable length 
— the favourite brooding-places of the gulls ; thousands and thousands 
of whose gray brown-spotted eggs we there found in their flat dish- 
like nests. The vegetation on the shores, which had lost much of 
its magnificence since we left the regions of the rapids and approached 
the Campos of Bolivia, became more and more prairie-like and poor. 
Low shrubs aiicj stunted bushes took tlxe place of the splendid trees 
of the lower A-alley', A small cluster of jxalms, bending over the 
smooth mirror of the water, enlivened only at intervals the dull 
monotony of the scenery'. Some spots on the left, Avhere the Pedra ' 
Cauga (a porous sandstone) appeared in horizontal strata, already' 
showed the native growth of the Campos; — nothing but strong, tall 
grass and thorny dwarf bushes. 
In the direction of the Campos between the. Guapor6 and the 
Machuixo, on which the ostriclies and the great stags, that already are 
getting scarce in the neighboxirhood of the Missions, are yet found 
in innumerable herds, we several times saw dense columns of smoke 
by day', and the reflection of fires by' night, lighted probably' by i 
wild Indians. On the left bank of the Mamore, the Campos un- I 
doubtedly' extend to the Jata and the Beni, affording excellent pasture ^ 
to the last remains of those enormous herds of cattle bred by the 
Jesuits a hundred years ago, and, after their departure, almost wilfully \ 
destroy'ed, in a manner which hardly' admits of excuse. 
As I shall have to revert to this theme, I may here only' mention 
* Soc tlie hydrographic results in the Appendix. 
