Nyantheae [sic] without basilar muscles. Body as a rule very elongate, more or less vermiform, often divisible into different regions. Aboral end of the body usually rounded being a physa often used for digging, which does sometimes adhere to small objects and then becomes more or less flattened. As a rule no sphincter, but when present this may be endodermal or mesogloeal. Tentacles and mesenteries usually few, rarely more than 48, cyclically arranged. Mesenteries as a rule divisible into macro- and microcnemes. Retractors of the macrocnemes usually strongly restricted, reniform, or circumscribed. Parietal part of the longitudinal mesenterial muscles commonly differentiated from the retractors forming a distinct parietal muscle together with the parietobasilar muscles. In the more differentiated genera acontia may appear.
Definitions and contained taxa are those of Oscar Carlgren as published in 1949 : Kungl Svenska Vetenskapsakadamiens Handlingar, Series 4, Volume 1, Number 1
Electronic version made possible by NSF grant DEB95-21819 in the PEET program to D. G. Fautin.