Males have a very large penis that is recurved to fit the shorter mantle cavity (see fig. 28.1 ). When out of the mantle cavity, it can assume a variety of shapes. The proximal 75% is almost uniform in width and appears to have white glands along the dorsal edge. The distal 25% is a tapering, glandless filament that narrows to the point where sperm is emitted.
Shell height 9.5 mm. Littoral, ELWS. Orkney,
Scotland. April 2018. Leg. I. Williamson.