Actinernidae with well-developed pedal disc. Column with very small mesogloeal papillae, the ectoderm of which forms small nematocyst batteries, cylindrical, in the distal part drawn out into 4 triangular lobes which are able to cover the oral disc and the mouth. No sphincter. Tentacles very short, conical, numerous in at least 2 cycles, largest at the apices of the lobes, the inner with narrow aboral mesogloeal thickenings at the base, the outer with slighter or no thickenings. Longitudinal muscles of tentacles ectodermal, radial muscles of oral disc very strong, chiefly ectodermal. 2 siphonoglyphs. Mesogloea of actinopharynx very thick. Numerous perfect mesenteries arranged in cycles, the partners equally developed. Weak retractors in lower parts of older mesenteries, parietobasilar muscles weak. Dioecious. Cnidom: see the suborder.
I. 4-lobatus 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
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