A list of species in the collection is given. Four of these are already known from S. African coasts; two, Anchialina typica (Kröyer) and Euchaetomera typica G. O. Sars, are new records for the region; two others, Siriella pondoensis and Mysidopsis eremita are new to science and are fully described and figured. Three rare species of Heteromysis—H. harpax (Hilgendorf), commensal with species of hermit crabs, H. gymnura W. M. Tattersall, captured in association with an ophiuroid and H. zeylanica found within the central cavity of a sponge are recorded from Zanzibar, the first record of the two latter from African waters. Additional notes, with figures, are given of their morphology and ecology, the distribution of the genus discussed and a key for the identification of its species given.