The first of the series (which appears to have no predecessor) single-lobed; the other four composed of two lobes, each subtriangular in section.
It is usual for the umbrella to have an even, circular, uninterrupted margin; but in the order Narcomedusae secondary down-growths between the tentacles produce a lobed, indented margin to the umbrella.
Not lobed or indented; tentaculocysts usually enclosed in vesicles; gonads on the radial canals.
As the aerial stem is traced down into the underground rhizome portion, these three mantles die out almost entirelythe central hydrom strand forming the bulk of the cylinder and its elements becoming mixed with thick-walled stereids; at the same time this central hydromstereom strand becomes three-lobed, with deep furrows between the lobes in which the few remaining leptoids run, separated from the central mass by a few starchy cells, the remains of the amylom sheath.
In the case of Dionaea muscipula we find a two-lobed lamina, the two lobes being connected by a midrib, which can play the part of a kind of hinge.