While cleaning out three shells of M. edulis several small crabs were found living inside the shell with the mollusc. One mussel had three individuals living with it two dirty brown about 3/16 inch in size and one pink 3/16 inch in length. These were all identified as pea crabs, Pinnotheres sp the difference being sexual, the males being smaller than the females. In J. Sincl (1906) two species are given as British, one usually associated with Ostrea edulis L and the other confined to Pinna fragilis Pennart ( = P. marina)
J. Sinel, 1906, An Outline of Natural History of Our Shores. Swan Sonnenschein & Co. , London.
C. A. Raffray