This monograph was originally intended as a continuation of “Swahili Phonetics”, which appeared in African Studies , vol. 1, nos. 2 and 3, 1942, but war-time typographical difficulties rendered publication impossible then. I am very grateful to the editor of the S.O.A.S. Bulletin for publishing it now. Although it may be read as a separate monograph, some knowledge of Swahili phonetics is necessarily taken for granted, and I have numbered the paragraphs as from the end of “Swahili Phonetics”, so as to allow for cross-reference to that article.