(Smith)
Description (shell):
Shell of six tumid whorls, often encrusted with black deposits so that little of the appearance of the spire is discernible. Last whorl large; aperture ear-shaped or oval, with a thickened peristome in mature shells; inner lip occludes umbilicus. In some shells, notably from brackish water populations, a spiral keel may be present, with or without periostracal bristles; some have a spiral row of bristles but lack keel.
Size:
Up to 6 x 3 mm.
Colour:
Beneath black encrustations the shell is pale horn-colour.
Animal:
Body with a long, narrow, bifid snout, evenly and darkly pigmented, with pale transverse band anteriorly. Cephalic tentacles long and setose, pale with darker base; white spot behind each eye. Mantle edge without pallial tentacle.
Habitat:
Common in a variety of freshwater and brackish (<16 รค) habitats, often with Ventrosia ventrosa in the latter. It is a New Zealand species, introduced to Europe by way of Australia.
Distribution:
Widely distributed throughout Europe.