(d'Orbigny, 1836)
Diagnosis: Shell with up to 3 whorls coiled at one level (involute). Last whorl swollen, aperture heart-shaped with blunt tooth extending on last whorl as faint keel or rib. Rostrum, or aperture tooth, variable in shape. Umbilicus deep. Embryonic shell with rough granulated surface both on proximal zone and first whorl (Boltovskoy, 1974b). Maximum diameter 1.5 mm.