MALARIA EXPEDITION TO NIGERIA 233 
Bugama, which are completely surrounded by miles of mangrove swamp, can be 
traced to no other source. At the African Association's factory at Slave Trees, no 
other breeding places can exist. The small area on which the factory stands is cleared, 
and surrounded also by a mud swamp covered by tidal water twice a day. Here 
myriads of Anopheles were encountered. 
In the region above the mangrove swamp — the forested belt — the natives are 
more of an agricultural than a fishing race, and consequently the ' dug-out ' canoe is 
considerably less in evidence as a breeding place, except in towns on the river banks. 
This district is flat, and its surface clayey. The natives build their huts of clay, dug 
out of pits in the immediate neighbourhood of their huts. These often contain 
water in which Anopheles larvae are easily found. In addition, ' puddles ' are also 
present in hollows either weathered or worn out in the clayey surface. In the large 
ponds and in the pools in the neighbourhood of springs from which the native obtains 
drinking water, and which generally contained fish, we were never able to find larvae, 
except in the small pieces of water locked off at the edges as the level of the water 
fell. These conditions obtain at Onitsha, Abutshi, Asaba, Abonnema, Degema, and 
Egwanga. 
In the immeciiate neighbourhood of European dwellings in this district, bad 
surface drainage, or the proximity of clay pits from which the ' boys ' obtain mud 
for huts, or of wells from which they obtain their drinking water, supply sites for 
Anopheles larvae. 
In the region above the forested belt, the country merges into a tract of 
deforested, more or less open, country, undulating and hilly, sparsely wooded, and 
covered with a short scrub. Here the breeding places of Anopheles consist of the 
pools, and back eddies, and sluggish corners in the course of the small streams 
running between the hills, of the badly-made ditches along the sides of roughly 
constructed roads and footpaths ; and occasionally, in swampy districts, of the furrows 
between the butts and drills of cultivated fields. Such conditions obtain at Lokoja, 
in Northern Nigeria. 
During the period of the expedition's visit to the river Niger, the rainy season 
prevailed. This river, which, in the height of the dry season (December to March), 
is reduced to the condition of a small sinuous canal, only admitting of the passage of 
launches drawing less than three feet of water, rises during the wet season a height 
of forty feet, and expands into a great river, reaching in parts a breadth of one to 
one-and-a-half miles. During the fall of the stream in the dry season it is said that 
numerous pools are left on the sloping banks, which afford breeding places for 
innumerable Anopheles. In some places, such as Asaba, a most rigorous search, both 
along the river banks and inland during the wet season, failed to reveal any breeding 
places for Anopheles. Pits from which mud is obtained for hut-building purposes 
are common ; almost each compound has its clay pit, partially filled with clayey 
