| From time to time crabs have been found in localities at great distances from their normal area of distribution, owing to their being transported by ships in ballast water tanks or on the hulls. Much attention has been paid to a report by Catta (1876), who examined the Crustacea taken from the hull of a ship that had made the voyage from India to Marseilles. Among these, four species of crabs of the family Grapsidae were represented, one of which, named by him Plagusia squamosa, being present in hundreds of specimens. Catta saw here the possibility of an extension of the area of distribution of the crab, but apparently the conditions of life were not favourable in the new locality, and the crab did not become established here. Stebbing (1893: 99) remarks... |
