Thenaria (Endomyaria) with distinct, often wide pedal disc. Column smooth, or with vesicles in its upper part. Sphincter strong, circumscribed. Tentacles very short, vesicle-like, often slightly lobed, few or many communicating with each of the main exo- and endocoels. Longitudinal muscles of tentacles and radial muscles of oral disc endodermal or mesogloeal. A single siphonoglyph, but two pairs of directives. All or most of the mesenteries perfect and fertile. Retractors very strong, strongly restricted or usually circumscribed.
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.