1: exterior (distal) face of the operculum consists of conchiolin with concentric growth rings originating from a peripheral nucleus at the base. 2: interior (proximal) surface is matt where the opercular disc attaches, and thickly varnished elsewhere. Large black mark at centre of matt area is also discernible on exterior face.
From shell H. 10.5 mm, Portland, Dorset, England, April 2012.
: flic.kr/p/2oiGpnC
Sets of OTHER SPECIES:
/