or MARCOU, ST, two small islets lying in the English Channel, off the coast of Manche in France, about 4 miles from the mainland, and 12 miles N.E. of Caretan. They are mere barren rocks, but in a military point of view are of considerable importance as defences for the roadsteads of Havre and Cherbourg. The navigation is here very dangerous, and they cannot be approached without a pilot. They were taken by the British in 1795, but restored to France at the Peace of Amiens.