The _Teredo navalis_[17] is very destructive to harbour works and piling. The Southampton water is particularly infested with it; in fact, the _teredo_ is found in every port to which coals are carried south of the Tees; in the Thames, as high up as Gravesend; and northward as far as Whitby. It is also found at Ryde, Brighton, and Dover. Traces of the ravages of the _Teredo navalis_, and of the _Limnoria terebrans_, have at various periods been found from the north of Scotland and Ireland, on almost every coast, to the Cape of Good Hope and Van Dieman’s Land, in the eastern hemisphere; and, in the western hemisphere, from the river St. Lawrence to Staten Island, near Terra del Fuego, almost in the Polar Sea; so that although this maritime scourge is rifest in warm climates, yet cold latitudes are not exempt from it. At the Crystal Palace, Sydenham, may be seen the destructive _Teredo navalis_ in a bottle, and there may also be seen mahogany perforated by it, and fir piles from Lowestoft Harbour, which were rendered useless by the ravages of the worm and the _limnoria_ three years after they were driven, showing the necessity of defending timber intended for marine construction. A specimen of American oak from the dock gates of Lowestoft Harbour, which had been four years under water, and a part of a fir-pile from the dockyard creek at Sevastopol, also show the destructive powers of the _teredo_. At the South Kensington and British Museums, London, specimens of this worm may also be seen, as well as pieces of timber perforated by it. The bottoms of ships, and timbers exposed to the action of the sea, are often destroyed by the _teredo_. The gunboats constructed during the Crimean war suffered far more from dry rot and the _teredo_ than the shot and shell of the Russians. One cannot even guess at the mischief perpetrated every year all along our shores, in docks and harbours, by the boring animals that penetrate all woods not specially protected. We cannot count the number of the ships that have foundered at sea, owing to those few inches of timber, on which all depended, being pierced or destroyed by the worm or fungus. In the short space of twelve years these destructive worms were known to make such havoc in the fir piles of a bridge at Teignmouth, that the whole bridge fell suddenly, and had to be totally reconstructed. The wooden piers of Bridlington were nearly wholly destroyed by worms; and the pile fenders on the stone piers at Scarborough were generally cut through in a few years. At Dunkirk, wooden jetties are so speedily eaten away that they require renewal every twelve or fifteen years. At Havre, a stockade was entirely destroyed in six months. At Lorient, wood only lasts about three years in the sea-water; and at Aix, the hull of a stranded vessel was found to have lost half its weight in six months, from the ravages of these animals.