Large adult from exposed coast. Thick shell-wall constricts throat of aperture; fits operculum. Shell-wall tapers rapidly from bosses to thin rim of  aperture.  Outer lip a smooth curve, interior slightly shiny.

Note that specifications of shell type related to exposure are average values of samples of 30 shells or more. Individuals can deviate from the average. This old specimen has an unusually thick heavy shell and tall spire for exposed coast.

Height 43.3 mm. Kincardineshire, N.E. Scotland. June 1971.