EN
Growth rate and age structure of Zonitoides nitidus (O. F. Müller) were studied based on monthly samples from a population in Muszkowice (SW. Poland). The life cycle is probably a three-year cycle: juveniles hatch from June till October, and winter over at a size of 2.0–4.5 whorls. The growth rate is ca. 0.5–1.0 whorl/month.