During the course of biological investigations for C.S.I.R. Fisheries Division, an officer of the Division collected several medusae in Marion Bay, on the east coast of Tasmania. These medusae (Cyanea capillata var. annaskala von Lendenfeld) were found to carry on the fringe and upper surface of the umbrella, a number of nude pedunculate barnacles, which correspond anatomically with Pilsbry's description (1907) of Alepas pacifica. The distribution of the species and its host relationship are discussed.