Genus Corythion Taranek, 1918
Diagnosis: test ovoid, asymmetrically compressed; lenticular in cross-section, lateral margins often slightly acute; aperture invaginated, oblique, oval, semicircular or round; anterior part resembling a spoon. Test composed of one type of body plates: circular, rectangular, imbricated, irregularly distributed but at lateral margins in rows. Apertural plates with one central tooth. Some species with a terminal horn or decorated with short spines. Nucleus vesicular.
Ecology: feeding on bacteria. In mosses, sphagnum and in soils.