The Tanganyika Problem. 



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 



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