Athenaria with elongate, vermiform body usually divisible at least into two regions, a long scapus provided with a cuticle and a short upper scapulus. Often there is also a rounded, naked physa at the aboral end and a very short, thin capitulum immediately below the tentacles. No sphincter or acontia. Mesenteries divisible into 8 macro- and at least 4 microcnemes. Of the macrocnemes there are two pairs of directives and four lateral mesenteries, two on each side, whose retractors face the ventral directives. Retractors diffuse to strongly restricted. Parietal muscles always distinct.
I have referred Halcampogeton and Synhalcampella, which previously have been placed in the Halcampoididae to the Edwardsiidae because they have only 8 perfect mesenteries.
Definitions and contained taxa are those of Oscar Carlgren as published in 1949 : Kungl Svenska Vetenskapsakadamiens Handlingar, Series 4, Volume 1, Number 1