Small, 1967
Body generally small. Infraciliature of paroral membrane may show reduced "a" and no "c" segment, while "b" is always clearly present; scutica posterior to paroral membrane, often in anterior part of distinct director meridian. Mucocysts and mitochondria very prominent. Most commonly in brackish or marine habitats including sand; many free-living; some inquilines in sea urchins or commensals in molluscs, coelenterates, annelids, sipunculids, and sea horses.
Family Uronematidae
Family Cohnilembidae
Family Pseudocohnilembidae