Perim (Arab. Mehun), an island belonging to Great Britain, in the strait of Bab-el-Mandeb, at the entrance of the Red sea, about 90 m. W. of Aden; area, 7 sq. m.; pop. in 1871, 211. It divides the strait into two channels, called respectively the Great and the Little strait. The former, between Perim and the coast of Africa, is about 13 m. wide, but its navigation is made dangerous by a group of volcanic islets called the Eight Brothers. Vessels to and from the Red sea usually pass through the smaller strait between the island and Cape Bab-el-Mandeb on the coast of Yemen, which is 1 1/2 m. wide. Perim is a rocky truncated cone of volcanic origin, about 230 ft. above the level of the sea in its highest part, and is almost destitute of vegetation and without water. On the S. W. side is an excellent harbor with a depth of seven fathoms, capable of holding 40 men-of-war. On the highest part of the island is a lighthouse, erected in 1861, and on Straits point are fortifications which command the narrow channel. - Perim was anciently called Diodori Insula. It was first occupied by the British in 1799, under the belief that Napoleon, who was then in Egypt, contemplated a descent on India, but it was abandoned in 1801. The project of the Suez canal again brought it into importance as commanding the new route to India, and it was again occupied formally on Feb. 14, 1857. It is under the jurisdiction of the governor of Aden.