Abstract.The validity and composition ofEctrepesthoneuraEnderlein are discussed and it is contrasted with the related genusTetragoneuraWinnertz. The occurrence of mid‐tibial sense organs in these genera and elsewhere in the subfamily Sciophilinae is considered. The EuropeanEctrepesthoneuraare revised and the secondary sexual characters of the male legs newly described. Two sgecies,E.pubescens (Zetterstedt)= messaurensisPlassmann, syn.n. andE.colyerisp.n., are added to the British list. The Nearctic species are discussed and the two eastern species dealt with fully: the male ofE.bicolor(Coquillett) is newly recognized andElaffoonisp.n. described. Some western NearcticTetragoneuraprobably belong correctly toEctrepesthoneurabut examination of types showed thatT.quintanaCole,T.longicaudavan Duzee and the eastern NearcticT.pimplaCoquillett belong toDziedzickiaJohannsen in its present broad usage. The PalaearcticEctrepesthoneura gracilisEdwards also probably has closer affinities withDziedzickiathan with its present assignment. The JapaneseEctrepesthoneuradescribed by Sasakawa (1961) are excluded as they are probably Sciarida