 The lectotype chosen for the species came from Marstrand , Sweden , but it is assumed to have been lost . In 1814 , writing for The Edinburgh Encyclopaedia , William Elford Leach erected a new genus , Carcinus to hold this species alone ( making it the type species of the genus , by <unk> ) . In 1847 , Nardo described a distinct subspecies occurring in the Mediterranean Sea , which is now recognised as a distinct species , Carcinus aestuarii . 
