Thenaria (Acontiaria). Sphincter mesogloeal. Mesenteries divisible into macro- and microcnemes, the older microcnemes may, however, be provided with filaments and acontia. Acontia with 2 categories of nematocysts, basitrichs and microbasic amastigophors.
Definitions and contained taxa are those of Oscar Carlgren as published in 1949 : Kungl Svenska Vetenskapsakadamiens Handlingar, Series 4, Volume 1, Number 1