FAUNA OF THE AFRICAN LAKES. 



571 



the exceptional facilities for distribution afforded by the thick- 

 shelled "resting" eggs of the Cladocera. 



A detailed survey of tlie distribution of the genera in the lakes 

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

 All the well re])iesented and more important genera a.ppea.r to 

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

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

 question. Chyclorus and Alona are the best represented genei'a, 

 each witli 6 species, Daplinia and Alonella following closely with 

 5 species each. From Albert ISTyanza, as already mentioned, 

 tliere is only the record by Brehm (54, ]>. 169) of a single species 

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

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

 R. T. Leiper [cf. 74), and though I have not yet found an oppor- 

 tunity of properly studying the Cladocera winch it contains, I can 

 at least indicate the occurrence of the genera Diajyhanosoma, 

 3Ioina, Cavi'jytocercus^ Alona, and Chyclorus. Having made no 

 speciiic deternjinations, these new records are not included in my 

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

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

 more into line with Lake Edward and the larger lakes. 



To sum \\\) — Lakes Tanganyika and Kivu quite unexpectedly 

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

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

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

 species in the lakes affords little of interest, many of the forms 

 being cosmopolitan and only an insigniticant number endemic. 



Branciiiopoda. 



Although representatives of this group have been found in 

 various parts of the African continent, there is, as far as 1 am 

 aware, only a single record which concerns the lakes under 

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

 CyclestJterJa Jiislojfi, was collected by Fiilleborn in the neighbour- 

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

 This form, originally described as Esilieria^ but subsequently 

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

 and its occurrence in the fauna, of Lnke Nyasa has no particular 

 significance. 



Pentastomida. 



These parasitic Arachnids have not, I believe, been hitherto 

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

 mens of Porocephalus from Tanganyika fish, encysted forms from 

 the body-cavity and others from the intestine. Tlie material has 

 been sul)mitted for expert examination, but no detailed report is 

 yet avai]al)le. Since the specimens came from very distinct 

 hosts — a Siluroid in the one case and a large 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 faunas. 



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