Actinernidae with thick column which expands more or less distally and is often but not always lobed, the lobes usually 8 in number. No sphincter. Tentacles, except the youngest and rarely the inner ones, with aboral thickenings or bridges of varying development which may run up the tentacles almost to their tips. Arrangement of tentacles usually in two cycles, the largest tentacles at the apices of the lobes. Longitudinal muscles of tentacles ectodermal, weak, radial muscles of oral disc ectodermal. 2 well-developed siphonoglyphs. Numerous mesenteries, the older ones developed as usual in the Endocoelantheae, after the stage with 20 mesenteries or somewhat later they continue to appear in definite zones in a bilateral way from the outer side of the zone inwards, usually. These mesenteries have the partners of a pair unequal. The longitudinal muscles of mesenteries as well as the parietobasilar muscles are weak. Cnidom: see the suborder.
A. nobilis Verrill 1879
A. michaelsarsi Carlgren 1918
Porponia antarcticus Carlgren 1914
Porponia elongatus R. Hertwig 1882
Porponia robustus R. Hertwig 1882
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.