I'AUNA OF TlllC AKUICA.N LAKKS. 571 



tlie excepbioutil f;icilities for distribution iifForded by the thick- 

 shelled " resting" eggs of the Cladocera. 



A detailed, siirve}' of the distribution of the geneiu in the lakes 

 does not seem csilled for, but certain features may be pointed out. 

 All the well represented and more important genera appear to 

 occur in two or more of the lakes, while it is the less outstanding 

 forms which are only known at present fi'om one of the lakes in 

 (juesbion. Chydorus and Aloua wxe the best represented genera, 

 each with 6 species, Daphnia and Alonella following closely with 

 5 s[)ecies each. From Albert Xyanza, as already mentioned, 

 there is only the record by Brehm (54, p. 169) of a single species 

 of Ikiphiiia. I have, however, in my possession a small quantity 

 of plankton from the lake collected in July 1907 by my friend 

 R. T. Leiper {cf. 74), and though I ha,ve not yet found an oppor- 

 tunity of properly studying the Gladocei-a wliich it contains, I can 

 at least indicate the occurrence of the genera Dicquhanosoma, 

 Moina, Gain2itocercits, Alona, and Chydorus. Having made no 

 S])ecific determinations, these new records are not included in my 

 list of forms, but attention is merely called to them in this place. 

 Tiie addition of these genera to its fauna brings Lake Albert far 

 more into line with Lake Edward and the larger lakes. 



To sum up — Lakes Tanganyika and Kivu quite unexpectedly 

 contain no Cladocera. This is very probably due to the salinity 

 of the water, and perhaps in particular to the excess of magne- 

 sium salts in those lakes. Apart from this, the distribution of 

 species in the la.kes affords little of interest, many of the forms 

 being cosmopolitan and only an insignificant number enden)ic. 



Bkanchiopoda. 



Although representatives of this group have been found in 

 various parts of the African continent, there is, as far as I am 

 aware, only a single record which concerns the lakes under 

 I'eview. A species belonging to the family Estheridse, viz. 

 GyclestJieria liislo'pi, wa.s collected by Fiilleborn in the neighbour- 

 hooil of Nyasa, though not actually in the lake itself (76, p. 159). 

 This form, originally described as I'jStheria^ but subsequently 

 separated from that genus, is of wide distribution in the tropics, 

 and its occnrrence in the fauna of Like Nyasa has no particular 

 significance. 



Pentastomida . 



These parasitic Ai'achnids have not, I believe, been hitherto 

 recorded from any African fishes. I obtained a number of speci- 

 mens of Porocephcdus from Tanganyika fish, encysted forms fi'om 

 the body-cavity and others from the intestine. T'he material has 

 been submitted for expert examination, but no detailed I'eport is 

 yet available. Since the specimens came from very distinct 

 hosts — a Siluroid in the one case and a la.rge Lates (Serranid) in 

 the other, — it may be they will prove to belong to different 

 species. It is open to question whether such forms should be 

 included in a description of lake faiinas. 



38^ 



