Port Lincoln Keyhole Limpet. Shell ovale, wider posteriorly, elevated, conical, perforation rectangular and small; yellowish to golden and blue within the interstices; radial ribs 18, prominent and larger posteriorly with one smaller interstitial radia between the 12 anterior major radials and two between the six posterior; concentric laminae 18, less prominent and intersecting the radials; internal callus typical. Animal is yellowish-orange completely contained by the more whitish shell which is centrally placed; mantle filaments projecting from the deep shell radials which form acute notches on the margin of the shell and corresponding narrow grooves internally; below these the mantle forms a skirt and beneath this is a row of epipodial filaments. Diameters 41 mm., and 29.2 mm., height 18 mm.