IRTON, (Cumberland) or IRTONDALE, to the S. E. of Egremont, long the manor and seat of a family of that name, on the side
of the r. Irt; in which are found the muscles, said to breed a sort of pearl, and called by the people shell-berries; and
some gentlemen got a patent for the said pearl-fishery, but we do not find that it turned to much account; and Dr. Lister
says they are only the scabs of old muscles.