640 REPORT OF THE HARVARD AFRICAN EXPEDITION 
such as are completely cut off from contact with the banks. These swallows 
course up and down the streams to which their activities are almost wholly 
confined. Equally characteristic of the edges of especially the smaller streams 
with wooded or bush-covered banks are the little gray River Flycatchers (Alseo- 
nax lugens) that seem to spend their entire lives within a few feet of the water’s 
edge, flitting from one perch to another or out across the current in pursuit 
of insects, and usually associated closely in pairs. Another flycatcher, a small 
blue-gray species, Fraseria cinerascens, also haunts the river banks keeping in 
the shaded underwood along the edges of quiet pools. Equally characteristic 
of the more open river shores, the rocks and sandy edges of the larger streams 
are the Pied Wagtails (Motacilla aguimp) which also are usually found a pair 
at a time here and there, seldom going far from the vicinity of the water. 
All these are rather common species that one might wholly miss unless he 
walked the stream banks or better still, followed the winding course of the 
rivers, large and small, in a native canoe. 
THE FOREST 
The dominant type of environment in Liberia is the great forest that covers 
much of the interior, becoming probably much less dense in the northeastern 
part of the country where rainfall is slightly less and where the human occu- 
pation has resulted in more extensive clearing and cultivating of the land. 
From available accounts, the southern half of Liberia is less thickly populated 
and the virgin forest covers the greater part of the area. To one who sees this 
forest for the first time, it is a thrilling experience, as if he had been translated 
into a new world. As seen from a canoe in passing up one of the many little 
rivers, the tidal swamps with their clean-trunked mangroves seem barren 
enough in the lower reaches, but once above the influence of tide water, one 
traverses a belt of screw palms and long-fronded Raphias that grow in vast 
swampy stretches and give so primitive an aspect to the landscape that it 
requires no imagination to feel that one is living back in Carboniferous times 
when such vegetation may have dominated this same country. As the land 
rises very slightly the trees appear in a boundless storied forest, with here and 
there giant silk-cotton trees standing above the rest, their clean pillar-like 
trunks rising well over a hundred feet before giving off their huge candelabra 
of branches.. Most of the trees are less lofty and form a second story, beneath 
which are ranks of lesser height, while the forest floor itself is covered by a 
growth of slender bushes and vines which in places may be open enough to 
be readily passable or again form dense and tangled masses, where the smallest 
vines are as tough as wire and often thickly beset with thorns so that progress 
is slow and tedious, and hardly possible for a white man in his civilized clothes 
without the help of wirecutters, though the native armed with a short, heavy 
bush-knife easily winds in and out, deftly cutting his way as he goes. In these 
silent forests it is noticeable that there is but little accumulation of humus or leaf 
mold, probably because the multitudes of ants, termites, and fungus agencies 
