FAUNA OF THE AFRICAN liAKES. 



585 



In the course of my expedition I collected in Tanganyika a. few 

 Trematodes wliich are parasitic on fish. They constitute a new 

 recoiTl for this lake, but have not 3^et been examined and 

 described. The specimens were taken from large Siluroids, in 

 one case from the gil] -arches, in another from the gut. 



Cestoda. 



As far as I have been able to ascertain, no i-ecords have been 

 published of tape-worms from the lakes included in this survey, 

 although Diulay described two new larv?e which he observed in 

 East African Copepods. Different forms of tape-worm proved 

 common in the gut of iishes examined for parasites by my 

 expedition, and I succeeded in getting a considerable number of 

 specinjens. These all came from Tanganyika, where I had l>etter 

 oppoitunity than elsewhere to seek such organisms, but it is 

 clear that systematic examination would not only bring to light 

 enteric parasites from the fishes of other lakes, but would result 

 in a far richer series from Tanganyika. My material has only 

 i-eceived a preliminary examination, so that little information 

 can yet be given as to the nature of the Tanganyika forms. A 

 species which occurred abundantly in an endemic Siluroid proves 

 to be one of the unsegmented Cestodes, and has been referred to 

 the genus Caryo'pJiyUmts. It has not been more fully identified. 

 Almost all the remaining specimens come likewise from endemic 

 fishes belonging to different genera of Cichlids and Siluroids. 

 Thus it is quite probable that other species of tape-worm- -perhaps 

 new forms — are represented in the collection. It is to be hoped 

 that the investigation will sliortly be completed. 



CCELENTERATA. 



The only representatives of this group at present recorded are 

 the common fresh-water Hydra and the medusa which so stimu- 

 lated interest in the fauna of Tanganyika. Stuhlmann obtained 

 specimens of Hydra from Victoria Nyanza which resemble the 

 common H. fusca, though Weltner, reporting on this mateiial, 

 would not venture to identify the species in the absence of eggs 

 (199, p. 2). Hydra has never been discovered in any of the other 

 lakes so far as I am aware, wliich is perhaps rather strange. 



The Tanganyika medusa was described by R. T. Giinther under 

 the name of Limnocnida tajiganicm * ( 94), and being peculiar to 

 the lake, was. of course, I'egarded by Moore as one of the most 

 striking halolimnic or relict forms. The significance of its 

 occurrence in this lake in the heart of Africa, which communicates 

 with the sea only by some tihousand miles of river, broken by falls 

 and rapids, Avas obvious, especially since the number of fresh- 

 water m.edusse then known was very small. Discoveries made since 

 Moore's expeditions, however, have put a very different complexion 



* The specific Dame is that of Bohm, the discoverer of the medusa, who wrote it 

 " tanganjicce.''' I follow Grinther (96, p. 651) and most subsequent writers in 

 adopting tanganicce as a more rational spelling. 



Proc, ZpoL. Soc— 1920, No. XXXIX, 39 



