1. Centripetal canals present, blindly ending or joining base of manubrium............................................................................................ 2
Without centripetal canals.................................................................................................................................................................... 3
2. All tentacles hollow; cnidocysts only in the terminal knob........................................................................... Calycopsis Fewkes, 1882
Two kinds of tentacles, large, hollow, with rings of cnidocysts and a terminal knob, and small, solid dwarf tentacles without terminal knob................................................................................................................................................ Eumedusa Bigelow, 1920
3. Radial canals simple, unbranched........................................................................................................................................................ 4
Radial canals branched; gonads folded or smooth............................................................................................................................... 6
4. Gonads smooth adradial............................................................................................................................ Pseudotiara Bouillon, 1980
Gonads smooth interradial................................................................................................................................................................... 5
5. 8 radial canals; marginal tentacles with abaxial basal ocelli........................................................................... Bythocellata Nair, 1951
4 radial canals; no ocelli............................................................................................................................. Protiaropsis Stechow, 1919
6. Radial canals branching repeatedly at various levels........................................................................................... Sibogita Maas, 1905
Radial canals simple or bifurcated....................................................................................................................................................... 7
7. 4 radial canals simple or bifurcated; gonads interradial, with transverse furrows; marginal bulbs absent..... Bythotira Günther, 1903
2 simple and 2 bifurcated radial canals; gonads smooth perradial; marginal tentacles with basal swellings embedded in mesoglea......................................................................................................................................................... Gymnogonium Xu & Huang, 1994