492 Bulletin American Museum of Natural History (Vol. LIII 
List of Land Mollusks of Penge 
Homorus ischnus 
Nothapalus paucispira xanthophaes 
Ptychotrema xquatoriale 
Gulella bistroplicina 
Subulina pengensis ‘‘ — pollonertana 
Pseudoglessula subfuscidula «pupa wuriensis 
i famelica ‘‘  toticostata 
af cruda : conospira polynematica 
Pseudopeas plebevum! Thapsia pompholyx 
Curvella langi “a cinnamomeozonata 
Gonaxis cavallir iturvensis = rufescens 
Streptostele centralrs Trochozonites plumaticostata 
eS he coloba ih bellula 
a dautzenbergr i irifilaris wturvensts 
5 bacillum a ally 
Ptychotrema quadrinodatum ie adansonre 
ai runsoranum Mesafricarion haliotides 
a sororcula . Helixarion insularis 
a fraterculus Pachnodus rutshuruensis 
stlvaticum Pleuroprocta silvatica 
i monotes | Cyclophorus intermedius 
ce cylindrus . 
In the virgin rain forest on dry ground of the Congo the surface of 
the soil, including leaf-humus, rotting logs and other débris, forms the 
main ecological habitat of land mollusks. Strictly arboreal species appear 
to be very few in number and are mainly Helixarioninee and Urocyclide, 
which after showers or in the early morning may be seen crawling over 
the leaves of low bushes. Whether there are in the Belgian Congo, as 
elsewhere in the tropics, peculiar snails adapted to living on the branches 
and foliage of the higher trees or in the clumps of epiphytes, cannot be 
said at present; none have been reported thus far from such a habitat. 
Where mosses, liverworts, and small ferns cover the clay or stone walls of 
ravines, especially near a spring, one is likely to make good malacological 
finds. It isin such a location that the junior writer discovered at Avakubi 
the minute operculate Cyathopoma africanum. Further investigation of 
similar places might probablv add to the extremely poor land operculate 
fauna of the Congo. The following species were also found at Vieux- 
Kasongo under decaying, very moist leaves near a spring in the forest: 
Ceras dautzenbergz, Gonaxis micans, Gulella levigata, Marconia kivuensts, 
Pseudoglessula stuhlmanni, Trochozonites bellula, and Cyclophcrus inter- 
medius; mostly, however, in dead condition. On the whole it is difficult to 
“y 
* 
1We regard at present Pseudopeas curvelliforme Pilsbry as a synonym of P. plebeium (Morelet). 
