210 
ON' THE OEOaKAPHICAL 
plateau surround, on the other side, the Alps of Abyssinia. 
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 kulla 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 under 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- 
port a greater 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 times they present in one or other situation, minute 
differences, which 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 I’ank 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 
