1901.] ON THE MOLLUSCS OF THE GREAT AFRICA]!^ LAKES, 461 



6. Further Researches concerning the Molluscs of the Great 

 African Lakes. By J. E. S. Moore. 



[Received June 18, 1901.] 



(Plates XXV. & XX VI.^) 



The interest whicli attaches to the Gasteropods helongiog to what 

 I have termed the ludoluiudc fauna of Lake Tanganyika h'es, one 

 may say almost primarily, in the fact that the?e molluscs, like the 

 remaining organisms contained in the Balolimnic series, are to be 

 found nowhere outside Lake Tanganyika, so far as is at present 

 known. 



Of these Gasteropods indigenous to Lake Tanganyika, there are 

 now known to be at least fourteen very distinct types, and these 

 have in consequence received the following generic and specific 

 names : — - 



Ti/jjhobia Smith. 



Bathunalia Moore. 



Kytra Moore. 



Limnotrochns Smith. 



Tanganyicia Cross. 



Stanleya Bourg. 



Faramelania damoni Smith. 



ParameMnia crassigranvlata Smith. 



Bythoceras irideseens Moore. 



Bytlioceras sp. indet. 



Syrnolopsis Smith. 



Spelcia Woodw. 



JSIelania calmircdnlis Smith. 



Nassopsis Smith. 



The existence of so many different forms of prosobranchiate 

 mollusca in any freshwater lake would be a most remarkable 

 fact ; but when, as in the case of Tanganyika, we find that these 

 fourteen distiuct forms are not only peculiar to Tanganyika, but 

 that they also co-exist in that lake together with the somewhat 

 numerous gasteropodous genera characteristic of the freshwaters 

 of Africa in general, the subject becomes one which is of peculiar 

 interest and worthy of the closest study. 



Besides the fourteen molluscan types which I have just named, 

 it was found, diu'ing the eleven months which I spent on or about 

 the lake, that there exist also in Tanganyika representatives of the 

 following gasteropodous forms : — 



Ampullaria. 



Lanistes. 



Physopisis. 



Planorbis, one or two species, 



Melania, several varieties. 



Neotlmuma. 



Vivipara. 



^ For explanation of the Plates, fee p. 470. 

 Peoc. Zool. Soc— 1901 , Vol. II. No. XXXL 31 



