210 ON THE GEOGRAPHICAL 



])lateau surround, on the other side, the Alps of Abyssmia. 

 It is from those lofty mountains, or from the northern 

 slope of the grand plateau of Africa in general, that the 

 largest rivers of that continent arise ; it is at the foot of 

 these mountains or terraces, where those wooded marshes 

 called kidla are formed, which surround, in the centre of 

 Africa, that grand basin of fresh waters which may be com- 

 pared to an interior sea. Presenting a more fertile soil, 

 the regions now vmder consideration are covered with a 

 more abundant vegetation than the rest of Africa; and 

 there the soil, and the rivers by which it is fertilized sup- 

 ])ort a gi'cater variety of animals, often belonging to very 

 different genera. This diversity in the physical constitu- 

 tion of different regions of Africa must necessarily exercise 

 a considerable influence on the geographical distribution 

 of the animals which dwell therein. The animals which 

 are more especially intended to inhabit the elevated plains 

 of the southern part of that continent, are often found on 

 every point of the grand plateau which combines the con- 

 ditions necessary to their existence. This is the reason 

 why many of the animals of the Cape of Good Hope have 

 been observed on the coast of Guinea, and even as far as 

 Abyssinia. Sometimes these animals are found to be 

 exactly the same, in regions very distant from each other ; 

 at other tunes they present in one or other situation, minute 

 differences, w^liich are often nothing more than slight 

 variations in the shades and vivacity of their tints, or per- 

 haps only in their distribution ; sometimes it happens that 

 these animals constantly differ, and in such an essential a 

 manner, as to justify the elevation of those different repre- 

 sentatives to the rank of species. On the other hand, we 

 observe a certain identity between many of the animals of 

 Abyssinia and of the Senegambia : those two regions very 

 often support the same species, the representatives of the 

 same animal forming sometimes local varieties, at other 

 times distinct species. The productions of those countries 

 shew sometimes an affinity with those of intertropical Asia ; 

 and we there even find several species of animals which 

 are also found in some parts of Asia, and even in Malayan 

 Asia. This identity is more remarkable still between the 



