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 record 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 form.s 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 Batrachiaiis which are widely distributed 

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

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

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

 belong to the Anuran Xenojyus, of which two species* need 



to be enumerated, 



1. Xenojms muelleri. 



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

 British Museum collection contains specimens from Lakes Tan- 

 gan3dka and Nyasa, and according to Tornier (192, p. 162) this 

 species was collected by Stuhlmann at Bukobaon Victoria Nyanza . 

 Its occurrence does not seem to have been i-ecorded from any of 

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

 parts of Tropical Africa, it is cjuite likely that it may exist in 

 them too. 



2. Xenojms la^vis. 



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 Rnsisi River which 

 flows into Tanganyika — though not reported actually from the 

 latter lake itself. This form likewise has an extended distribution 

 in Centi'al Afiica, and may very well occur in the other lakes also.. 



Since both these species are so widely distributed, it is prol)able 

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



* For the distinctions between the two species of Xenopus consult Koulenger 

 (27, p. 249). 



