Russell, 196
Imperfectly known, many specimens damaged. Two nominal species, information from both combined here based on Russell (1967), Larson (1986), Larson et al. (1988). Bell remarkably thin, broad, delicate, a rather flat inverted bowl when relaxed; up to ca. 60 cm diameter; mesoglea 1-2 cm thick, tapering towards edge; flexing down in "pursing" manner, margin closing to enclose large subumbrellar volume. Rhopalia reported 8 to ca. 20, number perhaps increasing during growth; rhopalar lappets minute to prominent, rectangular with circular ends. Marginal lappets not recorded, apparently very shallow or entirely lacking. Marginal tentacles lacking.
Subumbrellar musculature diffuse, probably extending over entire subumbrella. Coronal muscle well developed (but thin) comprising large number of circular, striated muscle fibres near bell margin; distal portion of muscle bending over toward subumbrella. Numerous fibres extending from coronal muscle to subumbrella. Stomach small, about 1/6 of total bell diameter, circular; protruding beneath subumbrella as short, thick-walled manubrial tube; oral arms 4-5, narrow, elongate, basal 1/3 held approximately horizontally, with near right-angled bend and remainder hanging down, terminating in curious hook-shaped organ. Base of each has on each side a "plaque" in which are numerous pits containing the gastric cirri, 3-10 mm long, up to 8 per pit. Gastrovascular canals fine, somewhat irregular-edged, forming reticulate network across most of bell, anastomoses more numerous closer to periphery; the spaces in the meshwork elongate, aligned radially. Radial canals 8 to ca. 20, both rhopalar and (? when >8) inter-rhopalar reported as discernible in some, but not in all, specimens, approximately twice width of those in main canal meshwork, running somewhat tortuously from stomach to a peripheral ring canal; ring canal noted as communicating with meshwork canals at broad intervals. Gonads reportedly 4-5, seen in only a few specimens, short-stalked and lobed, attached near base of oral arms.
Coloration: most specimens reported colorless but deep brown exumbrella and stomach lining a paler brown recorded once (Larson et al., 1988, as Deepstaria reticulum); more observations needed before value of this as species character can be evaluated.