Haeckel, 1866
Medusae with hemispherical or deep bell-shaped umbrella. Margin entire with thickened peripheral cnidocyst ring. Radial canals and circular canal present. With solid marginal tentacles or with mixture of solid and hollow ones. With or without centripetal canals. Manubrium with or without peduncle. Gonads usually on radial canals. Marginal sense organs as open or closed ecto-endodermal statocysts. Cnidome generally stenoteles associated with microbasic euryteles and/or atrichous isorhizae (Microbasic eurytele cnidocysts, Cnidocyst types). Reproduction by direct development, without polyp phase.
Family Geryoniidae
Family Halicreatidae
Family Ptychogastriidae
Family Rhopalonematidae