Euglenid flagellates, colourless, osmotrophic, elongated, tapering, cylindrical cells; canal opening apical; eyespot and flagellar swelling present (suggesting derivation from Euglena by loss of chloroplasts); cell semi-rigid but can bend and loop; paramylon grains are long needles and small ovals; 4 species, all freshwater. Type species: Cyclidiopsis acus Korschikoff, 1917.