The Flounder, one of the most common of the flat-fish, is found in the sea and near the mouths of large streams all round our coast, particularly where the bottom is soft, whether of sand, clay, or mud. It also ascends the rivers, and is caught in considerable quantities from Deptford to Richmond by Thames fishermen, who, with the assistance of an apprentice, use a net of a particular sort, called a tuck-sean. "One end of this net," says Yarrell, "is fixed for a short time by an anchor or grapple, and its situation marked by a floating buoy; the boat is then rowed or rather sculled by the apprentice in a circle, the fisherman near the stern handing out and clearing the net: when the circle is completed and a space enclosed, the net is hauled in near the starting-point in a direction across the fixed end." The Sail-fluke, a species of flat-fish common among the Orkneys, where it is highly prized as an article of food, its flesh being firm and white, is remarkable for its curious habit of coming ashore spontaneously, with its tail erected above the water, like a boat under sail, whence it has derived its name. This it does generally in calm weather, and on sandy shores, and the country people residing near such places train their dogs to catch it. In North Ronaldshay, the northernmost island of the group, a considerable supply is obtained in an original manner: thus described in a letter from a resident inserted in Yarrell's "British Fishes:" "In the winter and early spring, a pair of black-headed gulls take possession of the South Bay, drive away all interlopers, and may be seen at daybreak every morning, beating from side to side, on the wing, and never both in one place, except in the act of crossing as they pass. The sail-fluke skims the ridge of the wave towards the shore with its tail raised over its back, and when the wave recedes is left on the sand, into which it burrows so suddenly and completely that, though I have watched its approach, only once have I succeeded in finding its burrow.