FAUNA OF THE AFRICAN LAKES. 537 



Tanganyika, however, ^ is the extreme case, where not merely 

 specific but generic distinctions occur, and a remarkable fish fauna 

 exists which has very little in common with the fishes of the 

 Congo, and which, moreover, has no parallel elsewhere. 



Albert JSTyanza is the only lake of those under review which 

 does not contain a single endemic species of fish. The family 

 Siluridre is best represente;!, with 7 different forms, belonging to 

 6 different genera, but these are without exception well-known 

 Nilotic species. Very few Cichlid fishes are found in the lake, 

 the most interesting being Petrochromis andeisoitii, a Tanganyika 

 type, the existence of which in Lake Albert needs confirmation. 

 With this exception, and with the exception of Alestes viaa'o- 

 phthahnus, a Congo-Tanganyika type, the occurrence of which in 

 the lake is also rather doubtful, the whole of the fishes belong- 

 essentially to the Nile sj'stem, of which the lake is thus shown to 

 be an integi/al part. 



Lake Edward, which lies further south, but is similarly in 

 direct connection with the Nile, is nevei'theless not without types 

 peculiar to itself. Two endemic speces of Barbus have been 

 described, and one of Clarias. The Cichlidpe are well represented 

 here with 12 forms, 3 of which, including the genus Schuhotzia, 

 are endemic. While the greater number of the fishes are either 

 Nilotic types or are peculiar to the lake, there is a series of 

 6 Cichlids which are common to Lakes Edward and Victoria, and 

 are not found elsewhere. This is a rather unexpected state of 

 affairs, and it is by no means easy to account for the association, 

 since the lakes do not communicate in any way. It may be noted 

 that in Lake Edward the total number of genera is reduced to 

 eight and the number of families to four. 



Dealing lastly with Lake Kivu, the smallest lake is seen to 

 contain the smallest number of different species of fish. Yet 

 even here an endemic species of Barhus and two endemic Cichlids 

 occur. Apart from these, the fish fauna gives indications of 

 being considerably mixed. Three species belong clearly to the 

 Nile group, while reference has alreaxly been made to the two 

 forms of Haplochromis found in Lakes Kivu and Edward only. 

 On the other hand, two fishes are found in Kivu and Tanganyika 

 only : a third occurs in Tanganyika and the Rusisi E-iver which 

 drains Lake Kivii, as well as in the lake itself. The two I'emaining 

 types have a wider distribiition, extending into West Africa. 



In works dealing Avitli Geographical Distribution it has- long 

 been recognised that undoubted affinities exist between tlie 

 animals of Southern Asia — and of the Indian Peninsula in par- 

 ticular — and of East and Central Africa. While evidence of this 

 is more marked in some groups than in others, clear testimony 

 as to the general truth ot: the assertion is to be gained by a study 

 of certain families of fishes. Of the families under discussion, 

 it is pre-eminently the Cyprinidae and Mastacembelida? which 

 exhibit this affinity in a striking degree. Among the Cyprinidfe, 

 various genera are common to India and Africa, and a close 

 Proc. Zool. Soc— 1920, No. XXXVI. 36 



