14 Chthamalus montagui COMPARISON image of Semibalanus balanoides.

14 Chthamalus montagui COMPARISON image of Semibalanus balanoides.

Wall plates and opercular valves smooth. Triangular recessed alae and radii in upper half of wall. Radius (1) of wide rostral plate overlaps ala (2) of lateral plate. Pentagonal aperture. Diameter 8 mm. North Wirral, Cheshire, England. June 2011.