Actinodendronidae with very long arms, the oral faces of the arms free from tentacles, which are set along their sides. The ultimate branches of the tentacles simple and pointed.
M. hemprichii Ehrenberg 1834
H. griffithsii Saville Kent 1893
Definitions and contained taxa are those of Oscar Carlgren as published in 1949 : Kungl Svenska Vetenskapsakadamiens Handlingar, Series 4, Volume 1, Number 1