(Haeckel)
Diagnosis: Shell nearly spherical, slightly lenticular, somewhat compressed dorso-ventrally, sagittal diameter therefore somewhat shorter than other two. Borders of two hemispherical valves nearly circular, quite smooth, about as wide as largest pores. In frontal perimeter of shell 44- 50 pores, in half sagittal perimeter 20-24, in half equator 30-33. Pores different in form and size, marginal pores nearly small, circular; dorsal and ventral pores oblongish-hexagonal, twice as long as wide, 4 to 6 times as long as bars, in regular transverse rows.
Length: 0.22 mm.