H.B. Bigelow, 1909
Umbrella flat, lenticular; 16-26 marginal lappets; peripheral canals very broad throughout. Umbrella up to 40 mm wide; marginal lappets square, each with 5-7 statocysts; otoporpae shorter or slightly longer than width of transverse portions of peripheral canals; gonads sac-shaped when fully developed, with oval or papilliform processes.