1901.] ON IIIE MOLLUSCS OF TIIE CHEAT AFRICAN LAKES. 461 



6. Further Researches concerning the Molluscs of the Great 

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

 [Received June 18, 1901.] 

 (Plates XX Y. & XXVI.') 



The interest which attaches to the Gasteropoda belonging to what 

 I have termed the halolimnic fauna of Lake Tanganyika lies, one 

 may say almost primarily, iu the fact that these molluscs, like the 

 remaining organisms contained in the llaloinnnic series, are to be 

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

 known. 



Of these Gasteropoda 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 : — 



Typhohia Smith. 



Bathanalia Moore. 



Kytra Moore. 



Limnotroclms Smith. 



Tanganyicia Cross. 



Stanley a Bourg. 



Paramelania damoni Smith. 



Paramelania crassigran ulata Smith. 



Bythoceras iridescens Moore. 



Bythoceras sp. indet. 



Syrnolopsis Smith. 



Spekia Woodw. 



Melania admirabilis Smith. 



Nassopsis Smith. 



The existence of so many different forms of prosobranchiale 

 molhisca in any freshwater lake would be a most remarkable 

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

 fourteen distinct 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 fresh waters 

 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, during the eleven months which I spent on or about 

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

 following gasteropodous forma : — 



Ampullaria. 



Lanieh ■. 



Physopsis. 



Planorbis, one or two Bpecies, 



Mk lania, several rariel ies. 



.v, othauma. 



I Impara. 



1 For explanation of the Plates, iee p. 170, 

 Kool. Soc. L901, Vol. II. No. X \ XL 31 



