Borgert
Diagnosis: Large, thick-walled spherical shell, with small (1-3 times bar width) subcircular (elliptical) pores, wide bars. Small mouth with thick rim, with blunt protuberances projecting radially and tangentially into the mouth opening. Short (half shell radius) main spines. Numerous short (2-3 times pore diameter), thick by-spines.
Diameter: 0.65-0.9 mm.