Medusae with gonads forming separate interradial, adradial, or perradial longitudinal masses on walls of manubrium (exceptionally encircling entire manubrium). Mouth either with four simple or complex lips, or with circular mouth surmounted by oral tentacles. Marginal tentacles solid or hollow. Cnidome including usually desmonemes and microbasic euryteles, never stenoteles. Hydroids with filiform tentacles (except in dactylozooids of Ptilocodiidae).