Family METACYLIDIDAE Kofoid & Campbell, 1929

For	Coxliellidae;
Syns.	Calpionellidae p.p., Metacyclidinae, Metacylin[e]ae

Lorica tubular or goblet-shaped, delicate and with spirally wound lamina; aboral end sometimes with horn; wall may have prismatic structure and/or be agglutinated with coccoliths; practically all marine (eupelagic and neritic) forms, though occasionally one found in fresh water; a number of fossil species.

[The genus Coxliella - via its type-species, at least - may actually have no reality: as Laval-Peuto (1977) has very recently pointed out, there is a "coxlielliform" stage in the life cycle of many tintinnines, including species from a number of families. Thus I am here tentatively placing the generic name in a "questionable" status (see below) and replacing the former familial name (Coxliellidae) with the next name available for the group, viz., Metacylididae (originally the second included subfamily).]

Climacocylis Jörgensen, 1924. Several species.
Favelloides Colom, 1939. Few species.
Helicostomella Jörgensen, 1924. Several species.
Metacylis Jörgensen, 1924 (syn. Metacyclis). Several to many spp.
Pseudometacylis Balech, 1968. Single species.
Rhabdonelloides Colom, 1939. Several species.
Spiroxystonellites Knauer, 1969. Single species.
Incertae sedis:
Rhizodomus Strelkov & Virketis, 1950; single species.
Stylicauda Balech, 1951 single species.
Nomen inguirendum:
Coxliella Brandt, 1906. Many species [but see discussion, above.]