The Tanganyika Problem. 
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CHAPTER I. 
INTRODUCTORY. 
The desirability of obtaining a fuller knowledge of the 
nature of the aquatic faunae of the great African Lakes 
arose when it was first ascertained that in Tanganyika there 
are animals which have not the appearance of those we have 
grown accustomed to regard as of almost invariable and 
universal occurrence in the fresh-waters of the globe. Our 
knowledge of this singular circumstance originated, curiously 
enough, as a by-product of Burton’s celebrated journey to 
the lake. For although it will be generally remembered 
that Tanganyika was discovered by Sir Richard Burton, it 
may not be so generally remembered that his companion 
Speke picked up some shells on its shore, and that these 
eventually found their way into the British Museum. 
When examined, Speke’s shells proved to be quite un- 
like any fresh-water forms with which naturalists were 
acquainted, and it was at once recognised that in their 
general appearance they were curiously marine. 
As time went on, other great lakes in the African interior 
were visited by many Europeans, but no shells were ever 
I 
