Physochila principalis Chardez, 1919

Diagnosis: Shell oval, regular, circular or slightly compressed section, formed of a fairly thick organic cement, yellowish or greenish with a rough appearance, encrusting fine, very small polymorphic plates, generally not judging. Pseudostome more or less circular, often slightly multilobed, surrounded by a collar which tends to curve and form a kind of lip, in some individuals it flares out slightly.

Dimensions: Height 82-85 µm, width 55-58 µm, diameter of the pseudostome 25-28 µm.

Habitat: Ireland, marsh, among aquatic plants; peat bog, Campina, Belgium.