THE TANGANYIKA PROBLEM. 
34i 
interesting ; the Cichlidae, as we have seen, abound in Tan- 
ganyika, they are distributed more sparsely over the rest of 
Africa and in South-eastern Asia, but they abound also in 
the rivers of South America. Of the other families of fish 
which occur in Tanganyika, the Siluridae are apparently 
cosmopolitan ; and many types belonging to the group 
are at the present time marine. The Cyprinodontidae are 
peculiar to Europe, Asia and America. 
The Cyprinidae to Europe, Asia and North America. 
The Characinidae to Africa and Central and South 
America. 
The Polypteridae only to certain parts of Africa, including 
T anganyika. 
The Lepidocirenidae to Africa and South America. 
The Mormyridae are peculiar to Africa. 
The Mastacembelidae to Africa and Southern Asia. 
The chief feature of the distribution of these families 
which occur in Tanganyika now, is thus seen to be that 
they belong to groups which are found to be specially 
related to both sides of the Atlantic as it now exists. I see 
no reason to dispute the view originally put forward by 
Dr. Gunther, that the fresh-water fish-fauna of Central 
Africa has radiated from the region of the great lakes. 
For this view seems to be strongly supported by the 
evidence produced by Mr. Boulenger, who has shown 
that the Cichlidae of Tanganyika are among the more 
primitive of that group, and when we consider the 
above features of the distribution of the fishes, together 
with the facts, that there are marine animals in Tan- 
ganyika, and that the early representatives of these 
fishes were marine, there appears to be a very strong 
indication, indeed, that the fish-fauna of Tanganyika, as 
well as some portion of the fish-fauna of the American 
