across the stream. In some places they form miles
of flat rocky bottom, with islets covered with trees. At the cataracts
noted in the map, the fall is from four to six feet, and, in guiding up
the canoe, the stem goes under the water, and takes in a quantity before
it can attain the higher level. We lost many of our biscuits in the
ascent through this.

These rocks are covered with a small, hard aquatic plant, which, when
the surface is exposed, becomes dry and crisp, crackling under the foot
as if it contained much stony matter in its tissue. It probably assists
in disintegrating the rocks; for, in parts so high as not to be much
exposed to the action of the water or the influence of the plant, the
rocks are covered with a thin black glaze.

In passing along under the overhanging trees of the banks, we often
saw the pretty turtle-doves sitting peacefully on their nests above the
roaring torrent. An ibis* had perched her home on the end of a stump.
Her loud, harsh scream of "Wa-wa-wa", and the piping of the fish-hawk,
are sounds which can never be forgotten by any one who has sailed on
the rivers north of 20 Deg. south. If we step on shore, the 'Charadrius
caruncula', a species of plover, a most plaguy sort of "public-spirited
individual", follows you, flying overhead, and is most persevering in
its attempts to give fair warning to all the animals within hearing to
flee from the approaching danger. The alarm-note, "tinc-tinc-tinc", of
another variety of the same family ('Pluvianus armatus' of Burchell) has
so much of a metallic ring, that this bird is called "setula-tsipi", or
hammering-iron. It is furnished with a sharp spur on its shoulder, much
like that on the heel of a cock, but scarcely half an inch in length.
Conscious of power, it may be seen chasing the white-necked raven with
great fury, and making even that comparatively large bird call out
from fear. It is this bird which is famed for its friendship with the
crocodile of the Nile by the name 'siksak', and which Mr. St. John
actually saw performing the part of toothpicker to the ugly reptile.
They are frequently seen on the sand-banks with the alligator, and, to
one passing by, often appear as if on that reptile's back; but I never
had the good fortune to witness the operation described not only by
St. John and Geoffrey St. Hilaire, but also by Herodotus. However, that
which none of these authors knew my head boatman, Mashauana, stopped the
canoe to tell us