RESEARCH IN BRITISH WEST AFRICA. 191 
trees are replaced by evergreen shrubs and bushy trees. These furnish 
considerable shade, though not so dense as in the previous type, and are always 
associated with a tangled undergrowth. Figure 2 is typical of this class, while 
Fig. 2.—View near Bakau. Belt of evergreen shrubs and bushy trees with tangled 
undergrowth—a typical palpalis-haunt. 
fig. 5 shows certain modifications, in which the proportions of trees, bush, and 
undergrowth vary, and where Oil and Borassus Palms make their appearance. 
The variation in the nature of these belts is due almost entirely to the amount of 
surface moisture, the greater the amount of moisture the denser the under- 
growth. 
Where laterite predominates, and where there is consequently a much greater 
desiccation during the dry season, there are extensive stretches of thin bush. In 
this type, the trees are small, more or less crowded, and present a stunted and 
gnarled appearance. They are all deciduous, and there is little if any undergrowth. 
Such small shrubs and grass as appear during the rains disappear soon after the 
middle of the dry season. In laterite outcrops, where the influence of the rains 
is hardly felt, large expanses of small bamboos of stunted appearance are met 
with. 
A still more open type of country is seen in fig. 6 where there are practically 
no trees of any description and very little bush, but where grass predominates ; 
this is associated with sandy soil and is the favourite site for villages and 
farms. 
III. CLimate anv RAINFALL. 
The year is clearly divided into two seasons, a wet and a dry. The wet season 
continues from June to September inclusive, while the other seven months 
constitute a period of drought. The rainy season begins and ends with tornadoes, 
which commence early in June, and the rains proper about the end of July. 
The maximum rainfall (between one-third and one-half of the total for the year), 
