45 Patella pellucida. Growth Stages 3 (top left) & 4 (GS3 & 4) on Laminaria hyperborea frond. October 2013. Sublittoral. Egersund, S. Norway. © E. Svensen.

Most early adults (GS4) on fronds in Norway differ from those in Britain as blue lines usually continue onto new adult growth at the anterior in Norway (1) but not in Britain. But there are exceptions, some Norwegian frond dwellers (2) resemble the British.

 

Concise Key id. features: 1Pp flic.kr/p/Z4FxDe

Part 1, SHELL FORMS: 2Pp flic.kr/p/Z4FxAi

Part 2, BODY & ANATOMY: 3Pp flic.kr/p/Z4FxtK

Part, 3 HABITS & ECOLOGY: 4Pp flic.kr/p/Z4Fx9M

Sets of OTHER SPECIES: www.flickr.com/photos/56388191@N08/collections/

Done