Keferstein and Ehlers, 1861
Tubulariidae with single hollow marginal tentacle ending in large cluster of cnidocysts, without marginal bulb; with 4 perradial longitudinal exumbrellar cnidocyst tracks, 4 additional interradial and sometimes adradial ones; with vacuolated cells containing refractive droplets along 4 radial canals, at umbrella apex and bell margin; without non-tentacular marginal bulbs; manubrium occupying almost entire bell cavity; gonads surrounding middle part of manubrium.
Rhabdoon singulare