Familia Haloclavidae

Verrill, 1899

Athenaria lacking a sphincter muscle or with a weak, endodermal one. Column usually elongated, sometimes relatively short and stout, usually differentiated into regions. Aboral end rounded, without a limbus. Mesenteries not differentiated into macrocnemes and microcnemes, at least six pairs being perfect; imperfect ones, if present, being long and bearing retractor muscles. A single siphonoglyph is present, usually well-defined and sometimes more or less separated from the actinopharynx and aborally prolonged.