1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 513 
Sireptostele bequaerti M “ Helicarion”’ kivuensis M, K 
i centralis M | iS, schubotzt K, M 
Ptychotrema myrmecoén M i stuhlmanni K 
a mukulense M Kaliella barrakporensis M 
Gulella brevis M Cerastus retirugis M 
‘‘  pollonertana M bequaertt M 
‘f — masisiensis M m4 ‘‘  mokotoensis M 
Thapsia mukulensis M 4 ‘  mukulensis M 
Mesafricarion aurtformis K 7 lucast M 
Helixarion insularis K “ -  drymexoides K 
: niger M Cyclophorus intermedius K, M 
= maicrogranulatus M 
The outstanding differences between this mountain forest fauna of 
the Kivu highlands and that of the corresponding life zone on Ruwenzori, 
appear to be the presence in Kivu of the genus Achatina and the absence 
of Limicolartopsis and Bocageia. Whether these are merely due to insuffi- 
cient collecting must be left for future explorers to investigate, but there 
appears to be no reason why Limicolariopsis and Bocageia should not 
occur in the Kivu highlands. At present the terrestrial mollusk fauna of 
Kivu is best characterized by the unusual development of the enid genus 
Cerastus which reaches here its extreme eastern limits. Especially in the 
region of Masisi these beautiful snails are very commonly met with in 
the early morning crawling over the moss and dead leaves or crossing the 
pathways. They should be collected with great care, since the region 
certainly possesses many additional species as yet unknown to science. 
The Bugoie and Rugege Forests of northwestern Ruanda, a short 
distance from the eastern shore of Lake Kivu, at an altitude of 1,800 m. 
to 2,500 m., possess from all accounts a vegetation like that of the region 
of Masisi, so that one might expect them to have an equally profuse 
malacological fauna. Thus far, however, but very few species have been 
obtained there, as may be seen from the following list of available records’: 
Limicolaria saturata B, R “ Helicarion”’ kivuensis R 
Pseudoglessula obtusata R ie schubotzi R 
Gonaxis vulcant R Cerastus retirugis R 
Cyclophorus elatior B 
The Kivu highlands discussed thus far but rarely reach above 2,500 
m., so that there is as a rule no occasion for the development of other 
types of vegetation than bamboo and mountain rain forest. The top- 
most ridges of Rugege and the mountainous country west of Kivu and of 
1R =Rugege Forest; B=Bugoie Forest. These species have been mostly collected by Schubotz 
and Grauer. 
