Shell. Much like that of A. minor but differing in some respects. There are only 7-8 whorls; the spiral ridges, of which there are 4 or 5 on the last whorl, are more marked though they become less obvious near the outer lip.
Aperture. As in minor; the anal sinus is shallower, there is a more obvious peripheral bulge, and the outer lip shows a distinct basal flaring. The umbilicus is a mere chink, not particularly obvious.
Colour. White.
Size. 2X0.5 mm. Last whorl = 52-54% of total shell height; aperture = 30-35% of total height. Animal. Much as in A. minor. Colour. White.

Geographical distribution. From the Mediterranean to south Norway and rarely in the Skagerrak and Kattegat. Recorded from many localities in the British Isles but probably absent from the eastern half of the Channel and the southern parts of the North Sea. It is rare.
Habitat. On soft sandy bottoms between 10 and 50 m.