FAUiXA OF THE AFRIC AN LAKES. 



583 



lake. From Victoria Nyanza three difiereiit forms have been 

 reported, of which one was described as new and lias not been 

 fonnd elsewhere. The two remainii]g types were not specifically 

 identified, and indeed all three s})ecies from this lake rest on 

 a somewhat insecvu-e basis. None of the recorded species occur 

 in both Victoria and Nyasa, and it appears probable that none 

 were actually observed in the waters of the lakes themselves. 

 No Gastrotricha are known at present from any of the other 

 African lakes. 



TUIIBELLARIA. 



There can be little doubt that Turbellarians ai-e relatively 

 uncommon in the lakes as well as in other parts of Central 

 Africa. 8tuhlma,nn, a careful observer, wiio had opportunities 

 for collecting in many parts of the country, remarks on the 

 scarcity of these organisms, and in particular on the scarcity of 

 the fresh-water Dendrocoels, which are usually common in ponds 

 and streams (181, pp. 1262 & 1268: 182, p. 652: 185, p. 349). 

 During my expedition to the great lakes, I only observed Turbel- 

 larians in Tanganyika. They wei-e found on the under side of 

 stones in shallow water, and all proved to belong to a single 

 species of the well-known genus Flanaria. Prior to the 

 description of this Tanganyikan form by Laidhiw (107), the only 

 work dealing with species from the lakes was thatof Bohmig (17), 

 who reported on the collections made by Stnhlmann. Unfortu- 

 nately, the accounts in this paper are based almost entirely on 

 sketches and notes made on the spot, which often lack details of 

 importance for S3'stematic detei niination. Although the records 

 must thus be regarded as of doubtful value, 1 insert them here 

 without further comment. The following species * come within 

 tlie scope of this survey : — 



1 . Planar la tauganyikce. 



This is the type from Tanganyika to which reference has been 

 made. It is the only species known from that lake and has not 

 been obtained elsewhere. 



2. Stenosioma leucops. 



A form known in Europe and also in North America. On the 

 evidence of drawings, recorded from the neighbourhood of 

 Bukoba, on Victoria Nyanza. 



3. StenostoDia stuhlmanni. 



Described as new by Bohmig from Stuhlmann's notes and 

 sketches. Observed at Bukoba,, Lake Victoria and unknown 

 elsewhere. 



4. Stenostoma gilvuin. 

 Another species based only on a drawing and a few^ notes and 



* For details, consult the above-mentioned papers : Bohmig (17) and Laidlaw 

 (107). 



