(Haeckel)
Cephalis, globular, sometimes spiny, with a stout, 3-bladed apical horn. Thorax truncate-conical to campanulate, spiny, with large circular pores and 3 ribs which extend into massive, divergent feet. Highly variable species (species group?). Shell height (without feet): 50-100 µm.
Ref.: Riedel (1958), Nigrini and Moore (1979).