BOTANY. 211 



probably extended originally right across the 

 Victoria Nyanza to Kenia and Kilimandjaro, and 

 it may have extended southwards across the 

 Zambesi valley to the highlands of Mashonaland 

 and the Transvaal. The Central Watershed, 

 therefore, will form our second Floral region, 

 though it can be divided into marked sub-dis- 

 tricts. 



On the eastern side of this ridge the valleys of 

 the Sabakhi, Eovuma, and Zambesi have cleared 

 away a great portion of the soil, so that a sub- 

 mergence of this amount — 3,500 feet — would cover 

 a very large and irregular area, eating up to within 

 200 miles of Tanganyika along the course of the 

 Zambesi and Eovuma. This will make our third 

 great division. 



Now for the ocean which we have imagined as 

 submerging the first and third regions, let us sub- 

 stitute a warm and humid climate all over Africa 

 below the level of 3,500 feet. The facts, then, 

 are closely represented ; and we have in Tropical 

 Africa two humid climates — west and east — and 

 a central watershed which is comparatively dry. 

 These may now be considered in detail. 



The Westerly Wet Climate, or Niger and Congo 

 Flora, now extends across the Nile to the foot of 

 the Abyssinian mountains. It includes many of 

 the valleys of Euwenzori, the Semliki valley, and 

 Tanganyika. It is limited on the north by the 

 border of the Sahara. Throughout the whole of 



