ic boulders, especially on the left bank. On the
right bank was a beach of immaculate white sand. For 300 m. we went over
a great stony place with shallow water. We had to be careful, but all the
same many times did we bump with great force and get stuck upon submerged
rocks--which we could not see owing to the blinding, glittering
refraction of the sun upon the troubled waters.

A tributary 4 m. wide, coming from the north-east, entered the Arinos on
the right bank. A great number of rubber trees were to be seen on the
right bank, where the forest was luxuriant; but not on the left bank,
where the growth of trees was scanty. _Caranda_ or _burity_ or _tucuman_
palms were plentiful along the water's edge near the spot where a small
rivulet entered the Arinos on the left bank. Two thousand metres farther
down we came upon denuded country, low, and liable to inundation when the
river rose. Farther on were campos and open country, with the exception
of a thin row of trees immediately along the river. On the left we had
luxuriant forest, wonderfully healthy, neat and clean. The stream was
there beautiful--60 to 70 m. wide.

When we had gone 10 kils. 800 m. more the entire channel became strewn
with rocks and mounds only 1 ft. below the surface of the water, and not
unlike parallel small dunes of sand with a deposit of gravel upon them.
For 700 m. the river was obstructed and navigation rendered somewhat
troublesome.

Where the river turned from bearings magnetic 310 deg. to 360 deg. (due N.) we
went over a nasty stony place with a strong _corrideira_ above it, and we
were confronted with a rocky barrier almost the entire width across the
stream. We kept on the west side, the only way where it was possible to
get the canoe through. A little farther another _corrideira_, stronger
than the first, obliged us to find a passage on the east side of the
river--which bore upon its bank _campos_ and _chapada_. Curious mounds of
white sand and gravel were visible in the centre of the river, and also
near the left bank below the second _corrideira_; then we came to
parallel ridges of white sand and gravel right across the river bottom at
an angle of 45 deg. in relation to the general direction of the stream.

Two tributaries, one 3 m. wide on the left bank, the other 4 m. wide on
the right side (the latter coming from the north-east), swelled the
Arinos from that point. The width of the stream was now increased to 80
m., the water be