326
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
frequently found in Mytilus edulis although it has been reported from
Cardium edule, Ostrea edulis (Orton, 1920) and Cardium norwegicum
FIGS. 218 and 219. Pinnotheres pisum. (218) First crab stage (invase stage); (219) prehard stage. (Redrawn after Christensen, 1959).
(Smith and Weldon, 1904). It has been known since the days of the
Pharaohs and has been the subject of many colorful, although not quite
accurate, legends (see Calman, 1911).