FAMILY: ASSIMINEIDAE
The shell illustrated here lacks its operculum.
There are two British species in this family: Assiminea grayana Fleming, 1828 and Paludinella littorina (Chiaje,1828). The latter may be considered to be a marine species, in as far as it lives in rock crevices in caves and similar cavities high on the beach, and so is not included in this key. However, the former lives in the upper parts of salt marshes, where it is wetted only by spring tides, on mud, amongst the vegetation and in puddles, although it prefers emersion to submersion. It is therefore included as a brackish-water species.
Assiminea grayana
Fleming, 1828
Genus: ASSIMINEA Fleming, 1828
Assiminea grayana Fleming, 1828
Description: A squat cone, very nearly straight-sided in outline, formed of 6 – 7 slightly swollen whorls, the last of which is often slightly angled at the periphery. Umbilicus absent. Aperture 40 – 45% of shell height. The cephalic tentacles form short, rounded lobes with a large eye at its tip.
Size: Height: Up to 5 mm. Breadth: 3 mm.
Habitat: It is found in the upper parts of salt marshes, where it is wetted only by spring tides, on mud, amongst the vegetation. However, it can survive in normal sea-water, and can also survive long periods of desiccation. In Britain it is confined to the salt marshes of the east coast, from the Humber to Kent.