Schröder
Diagnosis: Spherical to nearly ellipsoidal shell, with circular to oval pores (about 2 times bar width). Small circular mouth with thick rim and 1-2 main-spines. Main-spines thick, about half shell radius, curved or flame-shaped. Numerous by-spines, about 2 times pore width.
Diameter: 1.10-1.25 mm.