Abstract
During a part of the years 1937 and 1938 a biological study of the fresh-water mollusca of the Tanganyika Territory and Zanzibar Protectorate was carried out with the aid of the grant of the Wandsworth Scholarship of the London School of Hygiene and Tropical Medicine. Up to the present little has been known about the molluscs of this part of Africa, although the importance of certain members of this group as the intermediate hosts of human blood flukes (Schistosomaspp.) has been widely recognized. The following account of the constitution and distribution of the molluscan fauna of this region may therefore be of interest and value.