Familia Diadumenidae

Stephenson, 1920

Thenaria with the base forming a well-defined adherent disc with a limbus; lacking a sphincter muscle or with a weak endodermal one; with ectodermal longitudinal muscle on the column; more than 36 tentacles in adults. Mesenteries not differentiated into macrocnemes and microcnemes. Nematocysts of acontia p- and b-mastigophores; catch-tentacles with holotrichs may occur but are not invariably present.