FAUNA OF THE AFRICAN LAKES. 563 



.sin<^]e species of Diaq^oinas wliich is peculiar to it, the lake 

 is chiefly cliaractevised by a iiuiubei- of I'emarkable foi'Uis belong- 

 ing to the genera Schizojiera and llycyphlhis, nearly tlie whole of 

 which are not known elsewhere. Even of the cosnjopolitan genus 

 (Jydo'ps^ 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 Lerno'ocera 

 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 genexu Diapfomtis, C'an- 

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

 of woi'ld-wide distribution. 



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

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

 Diapiomus, while there is a single endemic form of the sti'iking 

 genus Schizopera and one of Cyclops. Most of the remaining 

 species are widely distributed, a considei'able proportion being 

 well-known forms of Cyclops. Nyasa contains a, species of 

 • Ergasihis as well as Ergasiloides hrevimanus 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 the latter lake has been equally well 

 investigated. 



Seven species have been observed in Lake Albeit, of which 

 merely a single form {Ergasihis kanclti) is endemic. Apart fiom 

 this and from a species of Diaptomus found also in Lake Victoria, 

 the lake contains only representatives of the genus Cyclops, 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 that 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 

 Cyclojys. 



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

 an increase in the number of foims which they contain ; that 

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

 that Tanganyika possesses a large numbei- of unique types wliich 

 may well have been produced during a period of prolonged 

 isolation. 



Branchiura. 



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

 pai't on fish, was for long but pooi'ly 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 & 188, p. 37) and by Fillleborn in Nyasa (187/p. 47 

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

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