Haeckel
Diagnosis: Shell subspherical, smooth, both valves nearly equal in size and form, hemispherical. Three dimensional axes almost equal. Margins of valves dentate in nearly whole periphery, on each side of one valve 11 or 12 strong conical teeth, of equal size. Aboral hinge with 2 short, stout four-sided pyramidal horns of equal length. Mouth with two equal short lips. Pore subregular, circular, 3-4 times bar width, twice as larger in dorsal valve as ventral.
Length: 0.24-0.28 mm.