Both bear their round or ovoid male catkins at the ends of the slender terminal branchlets; the ovoid cones, either terminal or on short lateral twigs, have thick woody scales dilated at the extremity, with a broad disk depressed in the centre and usually furnished with a short spine; at the base of the scales are from three to seven ovules, which become reversed or partially so by compression, ripening into small angular seed with a narrow wing-like expansion.
Asplanchnaceae, plankton, dwellers in small pools, are, however, ovoid, and Trochosphaera is spherical and must owe its floating powers to the low density of the liquid in its enormously dilated bodycavity.
The light proceeds from a pair of conspicuous smooth ovoid spots on the pronotum and from an area beneath the base of the abdomen.
The beetles are ovoid in shape, with smooth contours, and the elytra fit over the edges of the abdomen so as to enclose a supply of air, available for use when the insect remains under water.
Shell external, globular or ovoid; foot elongated, parapodia separate from ventral surface; genital duct diaulic. Lobiger.