In addition to the family characters already mentioned, the hinge in this the typical genus is composed of two primary teeth in one valve, and one in the other, with accessory lateral teeth. The ligament is external, short, and swollen; the muscular impressions are rounded, and the connecting pallial impression is straight, with a wide and deep sinus, hollowed out toward the hinder side. The surface is covered with an epidermis.
Among the more beautiful of British shells must be reckoned the Polished Donax (D. politus). It is oblong in form, usually a little more than an inch in breadth, and about half that length. It is always vividly coloured, but varies much; the most common condition is of a pale golden yellow, or faint lilac hue, spotted and clouded with reddish brown; a broad pale ray passes from the beak to the margin. The interior, which, like the exterior, is highly polished, is generally of a rich purple, sometimes varied near the beaks with golden yellow or orange. The animal is of a bright yellow colour, with orange stripes and pink fringes; the foot is large and white. This lovely species, nowhere common, is found in many places on our southern coasts.