I 20 
CHAPTER VII. 
GENERAL OUTLINE OF TIIE ZOOLOGY OF THE GREAT 
AFRICAN LAKES. 
In order that a general appreciation of the nature of the 
Tanganyika problem may be obtained, I have prefaced the 
more detailed examination of the components of the fauna 
of the lake, with an account, or rather with a series of 
enumerations, of the different animals which have hitherto 
been recorded in each of the other great African lakes. By 
this means certain features of the distribution of the fresh- 
water fauna of equatorial Africa are rendered self-evident, 
and numerous repetitions which would otherwise be 
necessary in the sequel can be avoided. But besides this, 
so much that is new has recently been added to our 
knowledge of the composition of the faunas which exist 
in the great African lakes, that it is now for the first time 
possible to deal with the general characteristics of the 
equatorial African fresh-water fauna, and the results of such 
a study lead not only to conclusions which are interesting, 
but which are also by no means without importance from 
the broader biological point of view. 
There are thirteen great African lakes, about the fauna 
of which it can be said that something definite is known 
at the present time. 
