Characteristics of the Family (from Kramp 1961)
Rhizostomes with mouth-arms dichotomous and triangular or three-winged. A network of anastomosing canals communicate with the central gastral cavity in several places between the radial canals. Rhopalar pits smooth, without radial folds. Subgenital ostia without papillae.
With radial subumbrellar muscles. With eight rhopalar radial canals. Without a ring canal. With four more or less separated subgenital cavities. Subgenital ostia small, round. Stomach octagonal, with eight primary canals.
With numerous (more than three) inter-rhopalar radial canals in each octant; central portion of exumbrella with warts; with long, pointed filaments on the mouth-arms.