The genus Stephensoniella proposed by me in this Magazine (Ann. & Mag. Nat. Hist. ser. 10, vol. xv. p. 636, June 1935) is preoccupied for a genus of Enchytraeidae (Cernosvitov, Zool. Anz. vol. cv. p. 243, 1934). I propose to substitute for it the name POTAMODRILUS, nom. nov., for the species Potamodrilus fluviatilis (Lastochkin).