Diagnosis
Among the three species of Oxychilus in Canada, O. cellarius is intermediate in size. It is most similar to O. draparnaudi in that the spire is nearly flat, but the shell of O. cellarius is smoother and glossier, and the animal is paler in colour. O. alliarius has a smaller, rather darker shell and the animal produces a garlicky odour.
Shell
Small (mature shell width, 7-12 mm); growth indeterminate; depressed-heliciform; translucent. Whorls: ca 6. Spire: nearly flat; apex flat. Suture: indented. Last whorl: not descending to the peristome; no crest or constriction behind the baso-palatal lip. Periphery: rounded, medial on last whorl. Protoconch: smooth. Teleoconch sculpture: almost smooth, very glossy; weak colabral striae/wrinkles. Periostracum: shining, varnish-like. Umbilicus: small, about 1/6 of the shell width. Aperture: subovate, wider than high. Peristome: incomplete. Aperture dentition: none. Baso-palatal lip: thin-edged, not expanded. Peristome, viewed from side: prosocline. Parietal callus: glazed, transparent. Colour (periostracum): pale amber brown, slightly more opaque around umbilicus.
Animal
Grey, slighty bluish grey, with darker head and tentacles and with paler flanks. Brown flecks edge the sides of the foot and around the pneumostome are dense brown flecks (Grimm et al. 2010).