THE TANGANYIKA PROBLEM. 3 



known forms and probably of an ancient type. Nothing 

 more, however, could be said until some naturalist had 

 visited the spot, and this impossibility of getting any further 

 with the Tanganyika problem became the reason of the 

 first Tanganyika expedition. The exploration was organ- 

 ised by Professor Ray Lankester, who, with the help of 

 others interested in this matter, obtained from the Royal 

 Society the necessary grants in aid of the exploration, and I 

 finally set out in the autumn of 1896. 



As a result of the journey we found that the original pro- 

 blem presented by the jelly-fish had in no wise been solved. 

 It had, in fact, grown enormously bigger and more difficult, 

 lor it was found that in Nyassa and Shirwa there were no 

 jelly-fishes nor anything except purely fresh-water forms ; 

 while in Tanganyika there were not only jelly-fishes but a 

 whole series of molluscs, crabs, prawns, sponges and smaller 

 things, none of which appeared in any of the other lakes I 

 then knew, and all of which were distinctly marine in type. 

 Further than this, however, I* found that none of these 

 strange marine-looking animals were to be compared directly 

 with any living marine forms, yet, in their structure, some of 

 them certainly seemed to antecede a number of marine types 

 in the evolutionary series, and in consequence they appeared 

 to hail from the marine fauna of a departed age. The most 

 definite result of the first Tanganyika expedition, therefore, 

 appeared to be that the sea had at some former time 

 been connected with the lake, but when or how 

 remained a mystery. In discussing the inferences which 

 could thus be directly drawn from our observations respect- 

 ing the marine nature of the Tanganyika fauna before the 

 Royal Society in 1898, I found, however, that I had unwit- 



* " On the zoological evidence for the connection of Lake Tanganyika with the sea."' 

 Proceedings of the Royal Society, vol. 62. 



I* 



