L. Agassiz, 1850
Umbrella up to 300-400 mm wide, 3-4 times as wide as high, mesoglea thick in centre; manubrium 1/3-1/2 as wide as umbrella; 80-100 radial canals; gonads along greatest part of radial canals, leaving both ends free; marginal tentacles slightly more numerous than radial canals, with elongate, conical bulbs; with excretory papillae; numerous statocysts.