apparatus for screening pulp slurry in an annular screening zone in the space between a screen of circular cross - section and a closed surface drum carrying pulse creating means , the screen and drum being coaxially mounted for relative rotation about their common axis , is characterized by means for feeding the slurry providing at least one inlet to the space extending substantially the full axial length of the screening zone , and means for removing from the space rejects not passing through the screen having at least one rejects outlet from the space extending substantially the full axial length of the screening zone .