The chief forest types of the region are: (1) Evergreen forests of many spp., with a rainfall of 70 in. at least, extending over some 300 sq. mi.; (2) tall semi-deciduous forests with Sterculia, Albizzia, Trema, and others as characteristic genera. It requires 50-60 in. of rain and is now restricted to small relict areas; (3) temperate rain forest, with 50-60 in. of rain and temperate climate due to altitudes above 5000 ft., rather extensive; (4) semi-deciduous coastal forests of limited area; (5) plateau forests; and (6) cedar (Juniperus procerus) on the highlands of Kenya above 7000 ft. Present forest areas are separated from each other, but an increase of 15-20 inches in the rainfall of East Africa would be sufficient to cover practically the whole area with forest. This connection and a connection with the forests of West Africa existed 400,000 years ago, at which time occurred the dispersal of spp. Until 22,000 years ago opportunities continued for the montane flora and fauna now isolated to be merged with each other and with West Africa; isolation favorable to race differentiation has been the condition for the last 12,000 years only.