Members of the family Bithyniidae belong in the class of Gastropoda. These snails are characterized by their horn-shaped shells with a shell calcareous lid, or operculum. The operculum contains concentric rings although it may be necessary to scrape through algae and/or dry the snail to see them. The shell typically has 4 or 5 whorls and the total shell height is less than 15mm. We have found this family only in Lake Champlain. Bithynia tentaculata is an exotic species in North America and has been collected here since the 1800s.
Images of the concentric rings and the shell height.
More information on the class Gastropoda.