Shell of moderate to large size, up to 74 mm. (almost 3 inches) in length, solid, elevated; regularly, closely and strongly radially ribbed, the whole surface crossed by numerous lamellose concentric ridges that thicken into granular scales on the radials. Colour of exterior greyish, with the radials and a netted interstitial pattern in dark brown; interior brownish with the external pattern showing through strongly in brown or purplish brown. The well defined spatula varies from cream to orange-brown, and there is sometimes a bluish white area between there and the brown blotched margin. Radula: Formula (3) + 1 + (1+0+1) + 1 + (3). Radula very similar to that of radians, with both the pair of functional centrals and the pair of laterals with long lanceolate cusps set tangentially to the shank, and the lower cutting edge of the lateral is indented in two places. The nonfunctional fused marginal plates have three short parallel ridges at the base as in radians and flava.
Length: 43-74 mm; Width 35-63 mm; Height: 15-37 mm.

Shell solid, oval elevated. The sculpture consists of 22 to 30 prin¬cipal radiate ribs, and some smaller interstial riblets, all of which are closely scale-granose ; this character, however, is often lost in old shells through the dissolving action of the water. Apex more or less anterior, usually at the anterior fourth. Colour varies from light grey with brown ribs to dark brown. Interior bluish, central area well defined, orange-brown ; muscle-scar sometimes raised, bluish-white; space between central area and margin bluish-white, with dark-brown bands corresponding to the ribs; interspaces dotted with yellow spots ; margin with dark-brown triangular spots ; highly iridescent. Length, 55 mm. ; breadth, 43 mm. ; height, 24 mm. Length, 45 mm. ; breadth, 37 mm. ; height, 15 mm.

This shell is readily distinguished by its prominent brown scaly ribs, netted with brown in the interstices, and by its internal coloration, the spatula being cream to orange-brown, and the rest of the interior raved and netted in dark-brown upon a bluish grey ground.

New Zealand: Three Kings Islands, North Island, and northern part of South Island. This is the dominant limpet of the Cook Strait area, and from there it extends southward to at least Kaikoura. In its northern range, up the North Island east coast, it reaches the Three Kings Islands, but is not generally distributed in the north. These northern isolated small colonies are situated on certain jutting points and off shore islands, which evidently are catchments for larvae transported by coastwise currents.