FAUJ^A OF THE AFRICAN LAKES. 



563 



.single species of DlaptomLis which is peculiar to it, tlie Like 

 is cliieHy characterised by a number of remarkable forms belong- 

 ing to the genera Bcldzopera and llyo'ph'dus^ nearly the whole of 

 which are not known elsewhere. Even of the cosnjopolitan genns 

 Cyclops, Tanganyika exhibits 11 endemic types, as well as others 

 of wider distribution, while of the three species of Ergasiloides^ 

 two are found here alone. Two forms of the parasitic LeriuHocera 

 occur in the lake, one of which is likewise endemic. 



The Copepoda of Lake Victoria are referred not only to fewer 

 types, but form a much less interesting assembly. They comprise 

 a single endemic species in each of the genera Diaptomus, Can- 

 thocamptus, and Cyclops, but otherwise are forms of wider, often 

 of world-wide distribntion. 



A larger number of species is known from Nyasa, but out of 

 23, only 4 are endemic. Of the latter, two are species of 

 Diai>tomus, while there is a single endemic form of the striking 

 genus Schizopera and one of Cyclops. Most of the remaining 

 species are widely distributed, a considerable proportion being- 

 well-known fornjs of Cyclops. N3\asa contains a. species of 

 Ergasilus as well as Ergasiloides hrevlmanus which is otherwise 

 confined to Tanganyika. There is no reason to suppose that 

 Nyasa will be found to contain so many more Copepoda than 

 Victoria Nyanza when tlie latter lake has been equally well 

 investigated. 



Seven species have been observed in Lake Albert, of wliich 

 merely a single form [Ergasilus kandti) is endemic. Apart fiom 

 this and fi-om a species of Diaptoimis found also in Lake Victoria, 

 the lake contains only representatives of the genus Cycloj^s, which 

 are of fairly extended, and in some cases of the widest possible 

 range. 



Lake Edward with 3 species, and Kivu with 2, come last in 

 the series, and it should be noted tbat not only do they contain 

 very few types of Copepoda, but that these types have little 

 significance, being in each case widely distributed species of 

 Cyclops. 



It is thus apparent that with increase in size the lakes exhibit 

 an increase in the num.ber of foims which they contain; tliat 

 only in the larger lakes do endemic species appeal'; and, finally, 

 that Tanganyika, possesses a large numbei- of unique types whicli 

 may well have been produced during a period of piolonged 

 isolation. 



Branchiura. 



This small group of animals, which are parasitic for the most 

 pai-t on fish, was for long but poorly represented in the collections 

 from the great lakes of Africa. The collections made by Stuhl- 

 mann in Victoria Nyanza (184, p. 154) and Edward Nyanza 

 (187, p. 47 ik 188, p. 37) aiid by Fiilleborn in Nyasa (187, p. 47 

 & 188, pp. 37 & 44), resulted in a total of three species belonging 

 to as many genera. To these may now be added no fewer than 

 seven new species of Argulus which were obtained for the first 

 time by the Third Tanganyika Expendition (72), while there are 



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