Disc flat, flexing during swimming; mesoglea thin, transparent; maximum diameter reported 180 mm; marginal lappets elongate, rounded to shallowly pointed, rhopalial lappets slightly wider and longer than tentacular; probably increasing in number to a maximum recorded 64. Tentacles maximum recorded 48, arising at non-uniform intervals around bell so that intervening gaps are non-uniform till last is added; laterally compressed with row of wart-like structures along one side; stout basally but probably extensile to ca. twice disc diameter, in life held remarkably straight and at varied, irregular angles. Mouth arms 4, sides much prolonged and curtain-like, somewhat folded, about as long as disc diameter. Gastrovascular system comprising circular stomach in centre 1/3 of disc; radial canals about same width as gap between each and next, up to 96 reported, comprising 16 rhopalial canals and in each intervening paramere 1-5 inter-rhopalial canals; all essentially unbranched for inner 1/2-2/3 of length, somewhat regularly anastomosed in outer 1/3; some forking of rhopalial radial canals peripherally; both rhopalia and tentacles receiving a radial canal. When mature, the 4 gonads forming single wide ring around stomach, eventually protruding through; no subgenital cavity or ostia.
Coloration: possibly partly reflects feeding history. Recorded as transparent excepting canal system yellowish-brown, tentacles dull purple (Mayer, 1910); gonads and gastrodermis of stomach and oral arms orange (from photographs in Rybakov, 1976); gonads bright orange, rest colorless (BBC, 1993).