Three new species of Clithon (Mollusca, Gastropoda, Neritimorpha, Neritidae) are described from the Solent Group (late Eocene and early Oligocene) of the Hampshire Basin, England.

Continuing research into the fauna of the Solent Group, in particular by Alan Morton and Bill Pocock, has resulted in the discovery of new species. The Solent Group, which spans the late Eocene and the early Oligocene (Priabonian and Rupelian), (Insole et al., 1998, p. 19), consists mainly of non-marine deposits interrupted by a few, short-lived marine transgressions, the most extensive being that represented by the Colwell Bay Member of the Headon Hill Formation (Daley, 1999, p. 3). Clithon Montfort, 1810 are common in some brackish water deposits and they form an important part of the molluscan fauna. The opportunity is taken here to describe three new Clithon species which have recently been discovered and to comment briefly on the larval development of the Solent Group Neritidae, as indicated by their protoconchs.