(Quoy and Gaimard, 1832)
Pseudoconch transparent, with broad cavity occupying 1/2 or more of dorsal half. Tuberculation rather coarse, irregular, densest on dorsal side. Swimming disc broadly oval, not reaching far beyond border of pseudoconch in preserved specimens (may reach far over this border when alive), with two symmetrical tentacles and two horns of moderate length. Wing musculature consisting of a few opaque broad muscle bands forming 3 separate crossing systems visible in well-preserved specimens. Proboscis free from disc surface over nearly total length. Mantle gland slightly asymmetrical, with 4 broad bands and 3 narrow transparent bands, of which one is incomplete. No glands along wing border. Pseudoconch length 40 mm, diameter of swimming disc 80 mm.