Actinernidae with cylindrical body which distally is drawn out into 8 distinct lobes, four larger and four smaller alternating. Column without papillae. No sphincter. Tentacles in at least 2 cycles without distinct mesogloeal thickenings, largest at apices of the lobes, numerous. Longitudinal muscles of tentacles ectodermal, radial muscles of oral disc chiefly ectodermal, strong. Two broad siphonoglyphs. At least half of the mesenteries perfect. Perfect mesenteries cyclic in arrangement, beyond them weak mesenteries of unequal size in upper part of the body. Retractors weak, parietobasilar muscles rather well developed.
S. flavus Carlgren 1918
Definitions and contained taxa are those of Oscar Carlgren as published in 1949 : Kungl Svenska Vetenskapsakadamiens Handlingar, Series 4, Volume 1, Number 1