Introduction 



coasts in East Africa. Lakes Kivu and Edward are similarly 

 on the border line. Lake Albert is virtually East African. 



But east of the Albert, and north and east of the Victoria 

 Nyanza there still persist areas and patches of " West African " 

 forest, with the grey parrot, the large corytheola plantain- 

 eater, and many other West African bird types, the Bongo 

 tragelaph, the Potto lemur, and numerous West African 

 species of bats, rodents, hyraxes and Manis edentates. These 

 patches of forest with their " West African " beasts, birds, 

 reptiles, spiders, and insects really remain as relics of a 

 forest belt that in the Tertiary epoch passed continuously 

 across lands now arid or sunk in the sea between equatorial 

 Africa and India. In the Pleistocene a lessening in rainfall 

 or a lowering in temperature created the distinction between 

 prairieland and forest belt ; and the great fauna of Europe 

 and the Mediterranean basin passed through eastern equatorial 

 Africa where the forest was weakest, down to the prairie 

 lands and grassy plateaux of the South. 



The Albertine Rift Valley, so much the special sphere of 

 Mr. Bams's research, is just one of those districts where the 

 change of fauna and flora is most abruptly contrasted : for 

 he has stood where I have stood, facing north ; and almost 

 descrying from the same standpoint on the left hand the 

 abrupt ending of the dense forest with skulls of the small 

 red forest buffalo in the herbage ; and on the right, grassy 

 plains with only an occasional borassus palm or low-growing 

 acacia tree, teeming with East African antelopes, big-horned 

 Cape buffalos, zebras and rhinoceroses. 



He has likewise seen and known the Hamitic aristocracy 

 of these open grass countries, abruptly verging on the forest. 



xxxiv 



