A. Agassiz, 1863
Umbrella 50-65 mm wide, about 4 times as wide as high, watch-glass-shaped; mesoglea thick toward centre; manubrium broad, flat, 1/5 of bell diameter, circular to star-shaped in outline; mouth with 4 fairly short lips; 12-16 (17) radial canals in 4 groups branching usually within outline of manubrium; gonads linear, about 2/3 of radial canals; up to 450 marginal tentacles; 1 marginal cirrus between successive tentacles; about 80 statocysts.