Hydromedusa :: Hydromedusa (n.) Any medusa or jellyfish which is produced by budding from a hydroid. They are called also Craspedota, and naked-eyed medusae..
Medusa :: Medusa (n.) The Gorgon; or one of the Gorgons whose hair was changed into serpents, after which all who looked upon her were turned into stone..
Medusa :: Medusa (n.) Any free swimming acaleph; a jellyfish.
Trachymedusae :: Trachymedusae (n. pl.) A division of acalephs in which the development is direct from the eggs, without a hydroid stage. Some of the species are parasitic on other medusae..