Johnston, 1836
Leptomedusae with short manubrium; without gastric peduncle; typically with 4 radial canals (except in Gastroblasta and Pseudoclytia); with or without velum (no velum in Obelia); gonads on the radial canals, completely surrounding them and separated from manubrium; with hollow tentacles (except in Obelia, where they are solid and with short endodermic extensions into bell mesoglea); without excretory papillae or pores; without lateral or marginal cirri; numerous (16-200) closed marginal statocysts (only 8 in Obelia, located on the underside of the basal bulb of some of the marginal tentacles); no ocelli. Two genera: Clytia (with hollow tentacles and normal velum), and Obelia (with solid tentacles; without velum).
Genus Clytia
Genus Obelia