77 



PRESIDENTIAL ADDRESS. 



SOME REMARKS ON THE MOLLUSCA OF LAKE TANGANYIKA. 



By Edgar A. Smith, I.S.O. 



Mead V2th February, 1904. 



This interesting subject, the molluscan fauna of Lake Tanganyika, 

 has been much discussed during the last few years, especially by 

 Mr, J. E. S. Moore, and the final results of his investigations 

 are embodied in his work "The Tanganyika Problem." To the 

 uninitiated the study of this fauna is quite a limited matter, involving, 

 according to Mr. Moore, the consideration of only forty-six species of 

 molluscs belonging to twenty -eight different genera.' 



This apparent simplicity rapidly vanishes as soon as a serious 

 investigation is made of the literature which has been published upon 

 this subject. The late M. Bourguignat was the chief cause of all 

 the difficulty, having multiplied both the genera and species in an 

 absurd manner. Speaking of this writer, Mr. Moore" observes, "the 

 characters which were used by this author as sufficient to define 

 species and genera have not generally been held to be valid, even in 

 a conchological sense; they throw no light on the matter in hand, 

 and it is not necessaiy to discuss them further here." This is a very 

 simple method of dealing with a most difficult subject, but will not be 

 accepted by the systematist. Bad and useless as many of the species 

 and even some of the genera may be, still they have to be considered, 

 and an endeavour must be made to give to them their proper rank as 

 good species as understood by most conchologists, or to relegate them 

 to their true position as varieties or synonyms. To do this is one of 

 the objects of the present paper. M. Bourguignat has described 242 

 species, and of these only 13 appear in Mr. Moore's list! Surely the 

 remaining 229 are not all synonyms. His genera are 21 in number, 

 of which only four are quoted in "The Tanganyika Problem." I 

 quote these facts so as to show the general reader that the study of 

 the molluscs of this lake is not the limited affair he might conjecture 

 from a perusal of Mr. Moore's book. In addition, there are other 

 writers besides M. Bourguignat whose works or names are not even 

 mentioned by Mr. Moore. MM. Ancey, Giraud, Grandidier, Mabille, 

 Martel, and Dautzenberg have described seventeen so-called species 

 between them. Moreover, Professor E. von Martens has published 



1 " The Tangauyika Problem," p. 138. 

 * Loc. cit., p. 220. 



