These organisms live in cockles, oysters and other lamellibranchs and they so affect the gonads of these molluscs as to castrate and sterilize their host.
At the mouth of the Thames the gathering of cockles forms a considerable industry, especially at Leigh.
The cockles are gathered by the simple process.
In the cockles, in Cardium and in Trigonia, it is capable of a sudden stroke, which causes the animal to jump when out of the water, in the latter genus to a FIG.
The annual value of the shell-fish (lobsters, crabs, oysters, mussels, clams, periwinkles, cockles, shrimps) is about £73,000.
The cod, ling and herring fisheries are important, and the coasts abound with shell-fish, especially cockles, for which it has always been famous.