The observations are based on a 15-day excursion during the dry season in the Kokombo Valley near Mpwapwa. The valley, 3,500 feet in altitude, is surrounded by low gneiss mountains attaining a height of 6,100 feet. Annual rainfall is 19.9-44.7 in., with 1 rainy season (Dec-Apr.). June to Oct. are practically rainless months. Soils have a very low humus content, probably due to abundance of white ants. Plant formations are: (1) Deciduous scrub, quite varied in composition and exhibiting zonation on the mountains; and (2) subtropical evergreen forest weakly developed on the northern slopes of the mountains.