A Field Guide to the Snails of Lord Howe Island

33 Family Diplommatinidae (Staircase-Snails) The Diplommatinidae are very small snails, usually less than 10 mm in length, with high spired, ovately conical shells that coil to the right (dextral) or left (sinistral). The family is widespread, with one subfamily (Cochlostomatinae) found in eastern Europe and a second family (Diplommatininae) in southeast Asia, Micronesia, Melanesia and Australia. Diplommatinids are characterised by their small size and distinctive pupiform shape, and typically have shells sculptured with strong axial ribs. The last whorl is often either constricted or inflated and the aperture is usually strongly reflected. The operculum is horny and multispiral. Juveniles have an open umbilicus, but by adulthood the umbilicus is closed. Mt Lidgbird. Image I. Burghardt.