A rare copepod associated with eunicid worms is redescribed asEunicicola insolens(T.&A. Scott) nov. comb., and its occurrence recorded from the north‐east coast of Ireland, where it is found onEunice harassii.An interpretation of the mouthparts is appended, and a prior suggestion is reinforced that its affinities lie with the family Clausidiidae. Notes on the biology, especially as regards adhesion to the host, locomotion and feeding are also give