508 Bulletin American Museum of Natural History [Vol. LIII 
West African Subregion! and it is important to note that the Hast Afri- 
can montane district of Ruwenzori is thus entirely disconnected from 
regions with a similar fauna and flora farther to the east and the south. 
Almost everywhere the mountain range is surrounded by the savannas 
of the Uganda-Unyoro District. On the western side, however, the Lower 
Guinea Forest, which covers the valley of the mid-Semliki, send out an 
outlier, some 20 kilometers wide, up the slopes of the range to meet the 
zone of mountain forest. 
Four well-defined life zones, as characterized by the vegetation, may 
be recognized in Ruwenzori.? 
(1) The lower slopes between 1,500 m. and 2,200 m. are moderately 
steep and, owing to the abundance of freshly weathered rocks washed 
down from higher levels, are extremely fertile. They are intensively 
cultivated, beans being the chief staple crop; plantain bananas are not 
grown much above 1,800 m. Outside the cultivated areas, the hillsides 
are covered either with almost impenetrable thickets of elephant grass 
(Pennisetum purpureum Schumacher and Thonning), 2m. to 6 m. high, a 
conspicuous feature of the lower portions of this zone; or, above 1,900 
m. to 2,000 m., with dense fields of the common brake (Pterizdium aquili- 
num Linnsus). Within these are scattered a few trees, especially 
Erythrina tomentosa R. Brown and Albizzia fastigiata (E. Meyer), with 
an occasional Raphia palm. Higher up Vernonia auriculfera Hiern is a 
common bush of abandoned fields. The many ravines, however, are 
densely wooded and show a mu!titude of trees, with epiphytes,tree-ferns 
(Cyathea Englert Hieronymus), wiid bananas, and an abundance of 
heliophobic herbs, mosses and hepatics. This whole region of humid and 
warm temperate climate may conveniently be called the Zonr or 
CuLtTivaTion. As Mildbread has pointed out, there can be little doubt 
that most of it is covered with secondary plant formations. At least 
its upper portions, above 1.800 m., were originally part of the mountain 
cloud or rain forest typical of the next higher zone. The wooded vegeta- 
tion was cleared away to make room for native cultivation, which fact 
explains the very irregu'ar upper ‘mit of this zone. 
The malacological fauna of the zone of cultivation is comparatively 
rich, but does not essentially differ from that of the mountain cloud forest 
above. The snails and slugs are usually found under moss or !eaf-mou!d 
in the wooded ravines and may there occasionally be seen crawling over 
_ ‘Some of the mollusks obtained in thislowland region at the foot of Ruwenzori (especially at Kare- 
via, in 1,200 m.) by Stuhlmann have unfortunately been named ‘‘runsoranum,”’ though they do not 
beens to the montane fauna. 
recent, very complete account of the flora of Ruwenzori is given by JA. Engler, 1925, ‘Di 
Pflanzenwelt Afrikas,‘ V, 1, pp. 310-326. ai ae 4 
