Shell minute, thin, subdiscoidal but with convex spire, openly, umbilicated; unicolored ; whorls about 4, convex, the apical 1,5 smooth, rather distinctly demarked from the following whorls, which have oblique striae or irregular riblets and excessively fine spiral stride; the last whorl cylindrical, not descending in front. Aperture lunate, rounded : lip simple, thin. Type P. pygmaeum