1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo OTT 
In the south, east, and north, many small streams flow into the lake, 
the area drained being quite extensive, including the eastern slopes of 
Ruwenzori. Several of the Ruwenzori tributaries first empty in a de- 
pression to the northeast occupied by Lake George (Ruisamba or Dweru), 
which covers about 500 square kilometers and connects with Lake 
Edward by means of the broad Kazinga (or Kafuru) channel. Among 
the southern tributaries the Rutshuru ranks first, since it drains the 
northern slopes of the Mfumbiro volcanoes. The lake is thus well fed 
and there is a fairly steady outflow from its northwestern corner through 
the Semliki northward. The waters are but slightly brackish and still 
quite fit to drink. 
Lake Edward appears to possess unusually favorable conditions 
for the development of life, at least to Judge from the abundance of 
aquatic vegetation and the extremely numerous shore-birds, especially 
in the southern portion. The junior author, who made a brief visit to 
the lake in August, 1914, feels convinced that the animals thus far recorded 
represent but a fraction of the existing fauna, since a systematic explora- 
tion has never been attempted.! The known vertebrates include a water- 
snake and eighteen fishes; of the latter six species and one genus are 
endemic, the remainder being mostly Nilotic, although six species have 
only been found elsewhere in Lake Victoria. The fourteen lower inverte- 
brates include 2 Polyzoa, 11 crustaceans (1 prawn, 1 crab, 3 copepodes, 
1 Branchiura, and 5 Cladocera), and 1 hydrachnid; one of the Cladocera 
and the hydrachnid are endemic. All these animals belong to the usual 
fresh-water types. 
The Mollusea definitely recorded from the lake are listed below, 
the endemic species being marked with an asterisk. They total 19 forms 
(14 Gastropoda and 5 Pelecypoda).? 
Lymnxa natalensis undussumx *Burnupia edwardiana 
Planorbis bridouxianus *Pila ovata var. emint 
choanomphalus *Viviparus unicolor var. conoideus 
53 . var. basisulcatus  Bulimus alberta 
mete smithr Melanoides tuberculata 
FA sudanicus tanganitkanus *Corbicula radiata edward 
< gibbonst *Parreysia ngesiana 
ts fouladougouensis Ry sae regus 
tide apertus Bet stuhlmanna 
18peaking in general of Lakes Albert and Edward, J. E. 8. Moore (1903, ‘The Tanganyika 
problem,’ pp. 129-130) writes: ‘‘The fauna of both the Nyanzas is abundant—perhaps quite as abun- 
dant as that of Nyassa—but in both lakes it is composed of only a very few forms of fishes, and half a 
dozen species of Mollusca at the most. In many portions of both the Nyanzas the beach is composed of 
actually nothing else but the shells of Melania tuberculata.”’ He also claims that the fauna of Lake 
Edward is practically identical with that of Lake Albert. These hasty statements are not quite borne 
out by the facts. 
2The first mollusks of Lake Edward were obtained by Emin Pasha and F. Stuhlmann, travelling 
together in 1891-1892, and were recorded by E.v. Martens in 1897 (‘Deutsch Ost Afr., IV, Beschalte 
Weichth.’). Subsequent additions were mostly made by Gromier, J. E. 8S. Moore, Schubotz and the 
junior author. 
