FAUNA OF THE AFRICAN LAKES. 



575 



An examination of the table of distribution suggests in tlie 

 first instance tliat tliere are certain gaps in tlie list which future 

 investigation will surely fill. It is strauge, for example, that no 

 representatives of the Naiflomorpha have been found in Tangan- 

 yika or in the smaller lakes, for it does not seem likely that 

 they n,re entirely wanting. Secondly, it is clear that A^ery few of 

 the forms enumerated have been observed in more than one 

 lake, half of them being classed as endemic. Out of a total of 

 14 species, the highest number recorded from a single lake is 

 6 (Victoria NA^anza), 



There is no indication in this case of a mail^ed pre-eminence 

 for Tanganyika either in the number or peculiarity of its forms. 

 Lake Victoria, leads the way with 6 species, 4 of which are 

 endemic, Tanganyika coming second, with exactly half that 

 number (3 in all, 2 endemic). Lake Kivu also contains an 

 endemic form. The species are distributed among a, large 

 number of genera (nine), only two of which — Pygmceodrilus and 

 Alma — are represented by more than a, single type. Lake 

 Victoria again heads the list with representatives of four geneia, 

 Tanganyika and Nyasa coming next, each with three. No 

 endemic genera occur. 



It would serve no good purpose to review in detail the divStri- 

 bution of the different genera and species, but reference may be 

 briefly ma.de to the nature of the 01igoch?ete fauna of eacli 

 lake. Tanganyika alone contains a member of the Alluroidida*. 

 This worm — Alluroides tanganyikcp — was first described from 

 Tanganyika, but has since been obtained from Rhodesia in the 

 neighbourhood of the Victoria Falls. Two endemic species 

 of Ocnerodrilina; complete the list : there are no Naids or 

 Criodrilines known. — In Victoria Nyanza the types are more 

 uniformly distributed among the families concerned. Of folir 

 endemic species, two belong to the genus Pycimwodrilus and 

 one each to Aulophorus and Alma. — From Nyasa only three 

 Na,id genera of wide lange are on record. Fristina loiigiseta, 

 which I collected in that lake, is the only worm in the list which 

 occurs outside the continent of Africa,, being known both from 

 Europe and America. It is strange that other aquatic Oligo- 

 chjetes have not been forthcoming from this lake as a resnlt of 

 its careful exploration by Fiilleborn. — Lakes Albert and Kivu 

 each contain but two species. Two forms of Pygmceodrihis 

 (one endemic) come from Kivu, with one Pygmceodrihcs and 

 an Alma from Albert. No Naids have so far been observed. 

 These lakes, together with Lake Edward, have recently been 

 visited by the German Central Africa Expedition, and it is, 

 therefore, the more surprising that no Oligochsete worms have 

 been found in Lake Edward. 



HiRUDlNEA. 



There is but little known of the leeches which inhabit the 

 great lakes of Central Africa : indeed, there appears to be only 

 a single published record concerning them, which is that of 



