522 DR. W. A. CUNNINGTON ON THE 



(193, p. 583 & 194, p. 580) in Lake Nyasa also. It is not known 

 from any other African lakes. 



In this case again a larger number of forms is on i^ecord from 

 Tanganyika than from the other' Central African lakes, but the 

 species are all widely distributed, and their precise distribution 

 in the lakes is probably a matter of little significance. A 

 curious piece of negative evidence of considerably more interest 

 is the fact that, with one exception, there are no records of 

 Trionychidse from any of the lakes, although these forms are so 

 eminently aquatic and are known from other localities in Central 

 Africa. The exception to which I refer is Tornier's allusion 

 (193 &■ 194) to Cycloderma frenatum, a Zambezi species, in 

 Lake Nyasa. 



Batrachia. 



While there are many Batrachians which are widely distributed 

 in the African continent, the number of truly aquatic forms— with 

 which alone this paper is concerned — is veiy small. So far as I 

 am aware, the only true aquatics found in the lakes of Africa 

 belong to the Anuran genws Xenopus, of which two species* need 

 to be enumerated, 



1. Xenopus inuelleri. 



This form appears to be rather the commoner of the two. The 

 British Museum collection contains specimens from Lakes Tan- 

 ganyika and Nyasa, and according to Tornier (192, p. 162) this 

 species was collected by Stuhlmann at Bukoba on Victoria Nyanza. 

 Its occurrence does not seem to have been recorded from any of ' 

 the other big lakes, but as it is widely distributed in the Eastern 

 parts of Tropical Africa, it is quite likely tha,t it may exist in 

 them too. 



2. Xenopihs Icevis. 



Recorded by Tornier (192, p. 163) from Victoria Nyanza. 

 Subsequently recorded by Nieden (141, p. 186) from the same 

 lake and also from the western bank of the Rusisi River which 

 flows into Tanga.nyika — though not reported actually from the 

 latter lake itself. This form likewise has an extended distribution 

 in Central Africa, and may very well occur in tlie other lakes also. 



Since both these species are so widely distributed, it is probable 

 that their exact distribution in the lakes is of little moment. 



* For the distinctions between tlie two species of Xenojpus consult Boulena;er 

 (27, p. 249). 



