DONAXES. 281 
GENUS DONAX. 
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 mus- 
cular 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, some- 
POLISHED DONAX. 
times 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. 
