This belongs to the family of ark shells, so named on account of the fanciful resemblance of a Mediterranean species to Noah's Ark. A New Zealand species, Barbatia novaezelandiae, is oblong, is up to 2 in. in length and has an epidermis of stiff, dark brown bristles. At low tide it is attached by threads to the under sides of stones. The dog cockle grows up to 3 in. across, is thick and radially ridged, with a speckled pattern in reddish brown. It lives buried in coarse sand in from 3–25 fm.
Both these members of the ark family are easily recognised by the form of the hinge teeth, which are a series of simple interlocking short ridges and pits.
by Arthur William Baden Powell, Assistant Director, Auckland Institute and Museum.