(van Beneden, 1841)
Hydractiniidae with 4 or more solid, simple, marginal tentacles, not in groups; usually 4 or 8 simple or slightly branched mouth arms (which are dilations of the mouth rim) armed with clusters of cnidocysts; with or without gastric peduncle; gonads on manubrium, interradial, but sometimes extending along proximal parts of radial canals; with or without ocelli; sometimes asexual reproduction by medusa budding on manubrium.
Hydractinia tenuis
Hydractinia tournieri
Hydractinia minima
Hydractinia minuta