Family OXYTRICHIDAE Ehrenberg, 1838

Syn.	Pleurotrichidae

Clear-cut rows of right and left marginal cirri; frontoventral and transverse cirri typically heavy and distinctive; zone of adoral membranelles generally restricted to anterior third or quarter of relatively elongate body.

[Nomenclatural note: although O. F. Müller's Kerona is, strictly speaking, a senior synonym of Ehrenberg's Stylonychia, protozoologists have been unanimously favoring the latter name for more than 125 years; it seems advisable to leave matters that way (see also remarks under Keronidae, above).
Taxonomic note: perhaps this family deserves a (separate) subordinal standing of its own? See comment on Chapter 16.]

Actinotricha Cohn, 1866. Single species.
Ancystropodium Fauré-Fremiet, 1907. Single species.
Gastrostyla Engelmann, 1862. Several species.
Histriculus Corliss, 1960 (for Histrio). Several species.
Onychodromus Stein, 1859 (syn. Peritromoides). Single species.
Opisthotricha Kent, 1882 (syn. Opistotricha). Several to many species.
Oxytricha Bory de St. Vincent, 1825 (syns. Oxitricha, possibly Rhabdotricha?). Very many (ca. 50) species.
Parahistriculus Groliére, 1976 (syn. Parahistricus). Single species.
Parastylonychia Dragesco, 1963. Single species.
Pleurotricha Stein, 1859. Few to several species.
Steinia Diesing, 1866. Many species.
Stylonychia Ehrenberg, 1830 (syns. Kerona O. F. Müller [non Ehrenberg], Stylonichia). Many species.
Tachysoma Stokes, 1887. Several species.
Urosoma Kowalewski, 1882 (syn. Pseudostrombidium). Several spp.