1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian.Congo oll 
the moss; also a species of cranberry (Vaccinium Stanley Engler). The 
temperature is considerably lower than in the mountain forest and this 
probably explains the small number of species of land snails to be seen 
here, although most of them are common. Halolimnohelix TUWENZOTLESNLS, 
Vicaritheliz orthotricha, Haplohelix anadenia, Homorus olivaceus, Bocageia 
TUNSSOTINA, eee teres, and Voisicnciete bequaertiana are the only 
species obtained in the heath zone by the junior author. The predomi- 
nance of Helicide in this list is certainly worthy of attention; most of 
them have exceedingly soft shells, which it is hardly possible to pick up 
without indenting. 
(4) Above 3,500 m. one enters the ALPINE or Paramos ZonzE (PI. LIX), 
a region of giant, arborescent groundsels (Senecio adnivalis Stapf and S. 
Erici-Roseni Fries) and of tall torch-like lobelias (Lobelia Wollastonii Sp. 
Moore, L. Deckenit Hemsley and L. Stuhlmanni Schweinfurth); while 
higher up still the ground is covered with a dense carpet of small-leaved, 
tough-branched Alchemille (of several species) and numerous low bushes 
of various everlastings (Helichrysum Stuhlmannit O. Hoffmann, ZH. 
robustum Meoeser, and H. Lentizt Volkens and O. Hoffmann). Toward 
4,000 m. or 4,500 m. most higher forms of plant life disappear and the 
exposed rock only bears a few lichens and mosses. 
Only four species of land mollusks were seen by the junior author in 
the Alpine Zone of Ruwenzori: Halolimnohelix ruwenzoriensis, Vicarit- 
helix orthotricha, Homcrus olivaceus, and Vitrina oleosa. Most of them 
~ were found hidden between the stem and the leaf-base of the arborescent 
groundsels and in favorable weather were seen crawling over the leaves 
of these plants. The three first-named species also occur in the swampy 
zone of tree-heaths; but the Vitrina appears to be peculiar to the very 
highest regions of the range. It is apparently the only mollusk to reach 
the snow-line, in about 4,500 m. 
The region of the Kivu highlands is much more extensive than the 
Ruwenzori Range, since it covers most of the country between 1° and 5° 
S., and 28° and 30° E., wherever the altitude above sea-level is over 
1,500 m. It thus comprises the Mfumbiro Volcanoes, northwestern 
Ruanda with the Rugege and Bugoie Forests, and the western scarp of 
the Albertine Rift from Lake Edward to a little north of the outlet of the 
Lukuga River. Lake Kivu, at an altitude of 1,460 m. (4,830 ft.), contains 
several islands which also belong to the same zodgeographic region; 
the most important of these is Kwidjwi. Much of the surrounding terri- 
tory is covered with extremely fertile soil, partly due to weathered 
recent volcanic rocks, and consequently supports a large native popula- 
