« Shell usually weakly calcified, thin, cap-shaped, broadly ear-shaped or concealed by mantle, almost membranaceous. Aperture ear-shaped, pyriform, roundly ovate or irregularly ovate, ample, occupying most of frontal plane of shell. Spire consists of 1-4 whorls sunk into the very large last whorl or slightly projecting above it. Shell usually covered by differently developed periostracum (thin, membranaceous to thick, fibrous or setaceous). Edges of mantle thick, fleshy, sometimes project beyond the aperture, partly or entirely concealing shell and fusing over it. In the latter case, the shell is almost devoid of the calcareous layer, conchiolinous, having a soft membranaceous texture. Foot large, oblong or almost rounded with nodulated sole. Operculum lacking. » – Gulbin & Golikov: “A review of the Prosobranch family Velutinidae in cold and temperate waters of the northern hemisphere” part.1, Ophelia vol.47 (1), 1997, p47.
 

Shell small, spirally coiled, thin, pellucid, white, flat; the last whorl and its ear-shaped aperture exceed the 4/5 of the total height; the shell is entirely enveloped in the mantle.
 

Shell similar to that of Lamellaria. The differences are anatomical.
 

« Shell ear-shaped, with well developed periostracum and lining calcareous layer. Spire always projects above last whorl, of 0.5-3.5 whorls and impressed suture. Periostracum forms spiral and axial crests. » – Gulbin & Golikov: “A review of the Prosobranch family Velutinidae in cold and temperate waters of the northern hemisphere” part.3, Ophelia vol.51 (3), 1999, p229.