Tall profile with 8 whorls. Apical angle (1) about 35º.
Suture is emphasised by a subsutural collar of altered pattern and gradient (2).
Body whorl (3) about 60% of shell height.
Periphery of body whorl is smoothly rounded (4) on adults.
Fully grown adult with a thick, white, labial varix (5) set back from the thin, flared palatal (outer) lip (6) .
D-shape aperture about 40% of shell height (7); adapical angle about 65º (8). Mature adult with aperture lips forming a well developed continuous, everted/flared peristome around whole aperture that reflects onto the body whorl in the columellar (9) and parietal areas (10) and may form a very slight umbilical groove. Internally, the aperture is whitish, often with a brown band(11) between the varix and lip both externally and internally.
On active specimens with protruding tentacles, if the shell is translucent and not obscured by epizoic growth, the large penis is visible as a broad whitish band, often with a blackish line formed by the genital duct (12), but it cannot be seen through the body whorl if the animal is retracted into the shell (13). Shell height 9.5mm. Male. ELWS, Orkney, Scotland. April 2018. Leg. I. Williamson.

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