Sideractiidae with usually cup-like, small base. Body very low, smooth. Tentacles very short, at the apex distinctly knobbed, up to about 60 in number, arranged near the margin probably in 2 cycles. No discal tentacles. 2 weak siphonoglyphs. Muscles of mesenteries weak. Cnidom: spirocysts, atrichs, holotrichs, microbasic p-mastigophors and b-mastigophors?
N. singularis Gravier 1918
Definitions and contained taxa are those of Oscar Carlgren as published in 1949 : Kungl Svenska Vetenskapsakadamiens Handlingar, Series 4, Volume 1, Number 1