Genus: BATHYOMPHALUS Charpentier, 1837
Only one species occurs in northern Europe.
Bathyomphalus contortus
(Linnaeus, 1758)
Bathyomphalus contortus (Linnaeus, 1758)
Description: This shell has a very compact appearance, having 7 – 8 whorls which slowly increase in size. The whorls are half-moon shaped in cross-section, and are bluntly angled below, each whorl partially enclosing the preceding one. The shell is almost flat beneath, having only a slight umbilical depression, and it is concave above because the spire is sunken below the level of the body whorl. The general shape is so distinctive that it is most unlikely that this shell will be mistaken for any other.
Size: Height: 1.5 – 2 mm. Breadth: 5 – 6 mm.
Habitat: It is widely distributed throughout the British Isles in rivers, lakes and ponds.