BOTANY. 217 



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with forest, but it is not the dense steamy jungle 

 of the east and west wet low-level country, but 

 what one may call river woods, without bringing 

 the German term " Galeriewald " into requisition. 



The most curious feature of this central ridge is 

 the manner in which the flora changes as one 

 proceeds from north to south. Excluding for the 

 moment the true sub-alpine plants, belonging to 

 the region above 7,000 feet altitude, there is a 

 gradual transition observable from Abyssinia to 

 the Transvaal. The flowers of the Shire high- 

 lands, and particularly Mount Mlanje, are very 

 like those of the Transvaal. Those of the Masai 

 highlands show a less marked but still a perfectly 

 clear resemblance, while those of Kuwenzori and 

 Abyssinia have only a very general and perhaps 

 scarcely perceptible similarity. The explanation 

 is simple enough, on the hypothesis that the 

 ancestors of the present plants travelled down 

 the ridge from Abyssinia before the present basins 

 of the Nile (i.e., Victoria Nyanza), Congo, and 

 Zambesi had been eaten out to their present level, 

 while by the subsequent excavation of these and 

 other valleys different portions of the ridge have 

 since been isolated from one another by the inter- 

 position of climatic barriers. 



Thus the Malagarazi river has burrowed out a 

 large valley, which is colonised by Tanganyika, or 

 rather Congo plants. North of this valley, on the 

 east side of Tanganyika, are the hills of the Kiriba 



