FAUNA OF THE AFRICAN LAKES. 



Table of Distribution of Polyzoa'f. 



539 



Tvr c a • Tan2:an- Victoria 



Name of Species. ^^^^^^^^^ 



Order Gymnolj^mata. 



Victorella symbiotica E ? 



Arachuoidea ra^'-laiikesteri ... E 



Order Phtlactol2emata, 



Fredericella cunuingtoni E 



Plumatella repens P P 



„ einacgiuata P 



(Afrindella) 

 tangaiiyikse ... P 



6 species 3E 2P 2P 



Albert Edward 

 Nyanza. Nyanza. 



Other parts of 

 the world. 



Birket Qaruu ? 



Oosmopolitan. 

 Cosmopolitan. 



India. 



2P 



2P 



The above table iUustrates an interesting feature of distri- 

 bution, paralleled in the case of other organisms, where one or 

 more than one almost cosmopolitan species occurs in Tanganyika, 

 associated with a larger number of endemic forms. Plumatella 

 repens:, a form with a most extensive range, is represented in 

 Tanganyika as well as in Lakes Victoria, Albert, and Edward, 

 while the closely related P. emarginata is found in the latter 

 three lakes, but has not been recorded from Tanganyika. The 

 case of P. [Afrindella) tanganyikce is of considerably more interest, 

 for it Avas originally described as P. tanganijihe hy Kousselet 

 (149, p. 252) from material collected by the Third Tanganyika 

 Expedition. It was at that time believed to be peculiar to Tan- 

 ganyika, but Annandale (5, p. 225) subsequently referred to this 

 identical species, specimens whi[3h he obtained from Igatpuri 

 Lake in the Western Ghats, Bombay Presidency Still more 

 recently (8, p. 140) the same author established the subgenus 

 Afrindella to receive the species, indicating in the name the 

 striking feature of its distribution. The absolute identity of 

 forms from Tanganyika and from India is a most remarkable 

 instance of those Afro-Indian affinities to which reference has 

 already been made J. 



The remaining phylactolaamatous form, Fredericella cunni7ig- 

 toni, has sufficiently marked peculiarities to distinguish it from 

 the well-known P. sidtana, which has an almost world-wide 

 distribution. The former is confined to Tanganyika as far as is 

 at present known. 



Among the great lakes of Central Africa, Tanganyika alone 

 has been found to contain representatives of the Gymnolfemata. 



f For descriptions of most of these species and remarks on distiibntion, see the 

 report by Rousselet on the Polyzoa of the Third Tanganyika Expedition (149). 



The>e specimens he at tirst named F. bombai/emis (4, p. 169) — a species aftei- 

 wards discarded. 



X A table of African and Indian Polyzoa is given by Annandale in his paper on 

 the resemblances between African and Indian fresh-water faunas (10, p. 582). 



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