Summary.The morphology of the freshwater medusa,Limnocnida rhodesiœBoulenger, obtained from new sites in the Zambesi and Limpopo river‐systems, is described and illustrated by photographs (Pl. I.).The new sites forL. rhodesiœare the Prince Edward Dam on the Hunyani River, near Salisbury, the Hartebeestpoort Dam on the Crocodile River, near Pretoria, and the Bezuidenhout Valley in Johannesburg.The range of dimensions ofL. rhodesiœis extended, the present specimens being larger than those previously described.The specimens ofL. rhodesiœexamined from the new localities were all females in active egg‐production. Manubrial bud‐formation was seen in only a few specimens.A species ofTrichodinaoccurred in small numbers on the external surface and tentacles ofL. rhodesiœfrom the new localities cited.Some ecological notes onLimnocnidaare given.The present geographical distribution of the genusLimnocnidais discussed and the continued southward range of distribution in Africa from Lake Victoria Nyanza to Johannesburg is detailed. Similarly, the distribution of the known species ofLimnocnidais given,L. tanganicœ, the Central African form, being replacedby L. rhodesiœin Rhodesia and the Transvaal, andby L. indicain India.The possible significance of the present‐day geographical distribution ofLimnocnidain relation to former geological conditions on the earth's surfac