Pedal disc more or less well developed. No sphincter. Tentacles with distinct acrospheres, arranged in cycles, not more than one tentacle to each endo- and exocel [sic]. Spirocysts numerous.
Definitions and contained taxa are those of Oscar Carlgren as published in 1949 : Kungl Svenska Vetenskapsakadamiens Handlingar, Series 4, Volume 1, Number 1