,500 m. farther down a long narrow island (200 m. long, 80 m.
wide)--Gemma Island--heavily wooded, was passed and admired. It had the
usual gravel spit on its southern or up-stream point, the river in that
particular spot flowing due north in a perfectly straight line for 4,000
m. The island stood in the centre of a basin 200 m. broad. There were
_campos_ and _chapada_ on the left bank.

We landed on the island, and found most beautifully clean forest, nice
and cool in the greenish dim light which penetrated through the dense
masses of foliage. Particularly noticeable for their beauty were the
handsome large mimosas.

On the right bank of the river was forest with plenty of rubber trees,
but occasionally even on that side patches of what the Brazilians call
_serradao_ (close forest) were met with.

A hill range 120 ft. high formed a crescent from west to north-west on
the left side of the stream. A kilometre and a half farther forest was to
be seen on the left side of the river; whereas on the right was _chapada_
and _campos_, quite open. A picturesque rocky island, 15 m. in diameter,
in laminated horizontal and rich brown volcanic rock, rose 3 ft. above
the water in the centre of the stream. From that spot for 2 kil. I
noticed _chapada_ on the right bank; then after that was beautiful dense
forest on both sides, with innumerable vigorous rubber trees.

The river there was 200 m. wide and had shallow water with strong
_corrideiras_ over enormous parallel transverse dunes of sand and gravel
which formed the bottom. Islets of gravel were exposed, especially near
the left bank and in the centre, leaving only a more or less navigable
channel near the right bank.

We ran aground many a time along the 500 m. of shallow water, varying
from 6 in. to 3 ft. deep. We emerged into a large basin 300 m. wide where
eddies of no great strength were formed. On the edge of the beautiful
basin we halted for our lunch, and to take the usual astronomical
observations at local noon. We were in lat. 12 deg. 26'.5 S.; long. 56 deg. 47'
W.

I do not know if I have ever seen such swarms of bees and butterflies as
I saw at that place. They seemed to swoop down upon us in myriads from
all sides. Taking the solar observations with the sextant and artificial
horizon, I endured positive torture with the hundreds of bees which
settled on my forehead, nose and hands; while thousands of mosquitoes and
ants stung my legs, arms and face in those spo