Class Oligochaeta Grube, 1850 - oligochaetes see [unranked] oligochaetous Clitellata Subclass Tubificata Jamieson, 1988 Order Tubificida 1 Family Tubificidae Vejdovský, 1876 - sludge worms see Family Naididae Ehrenberg, 1828 2 Family Enchytraeidae Vejdovský, 1879 3 Family Capilloventridae 4 Family Phreodrilidae 5 Family Dorydrilidae 6 Family Opisthocystidae see Family Opistocystidae Černosvitov, 1936