Genus Cyclopyxis (Deflandre, 1929)
Diagnosis: Shell brown; in ventral view circular, in lateral view hemispherical; composed of agglutinated mineral particles; aperture central, invaginated, circular, sometimes with internal tube; few species with irregular or lobed pseudostome, margin never with thick organic lip but often with small mineral particles. Ventral surface usually smooth, dorsal part rough with larger sand grains.
More than 30 species and twice as many varieties. Type species: Cyclopyxis arcelloides (Penard, 1 902)
Ecology: sphagnum mosses, soil.
Key to the species: