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CHAPTER III. 
ON THE EXISTENCE OF A GREAT CENTRAL MOUNTAIN CHAIN 
IN AFRICA. 
In entering upon an enquiry concerning the nature of the 
fauna of the great lakes of Central Africa in general, and 
that of Tanganyika in particular, it is, if not absolutely 
necessary, at any rate advisable, that a conception of the 
structure of the continent, as concise and accurate as 
existing observations will permit, should be formed first. 
On this account I have prefaced the chapters dealing with 
the zoology of the Great Lakes by some in which the 
structure and the geology of the vast regions in which 
the lakes lie has been described as fully as our yet 
scanty information will allow. In the present instance 
this course is doubly to be desired : our views respecting 
the continent are becoming changed, and some very 
definite theoretical anticipations which have been put 
forward concerning the gross geological features of the 
African continent appear, in the light of the most 
recent exploration, to have hardly even a shadow of 
support. These older geological anticipations are, more- 
over, diametrically opposed to some of the most salient 
zoological facts relating to the fauna of Lake Tanganyika, 
and consequently any fresh information about the geo- 
