ATLAS, a mountain-chain of Northern Africa, between the great desert of the Sahara and the Mediterranean. The range has been but partially explored, and geographers differ as to its extent, some considering it to reach from Cape Ghir i on the Atlantic to Cape Bon, the north-east point of Tunis, i while others include under the name the whole mountain j system between Cape Nun and the greater Syrtis. In i this latter sense it forms the mountain-land of the countries of Marocco, Algeria, Tunis, and Tripoli. It is composed of ranges and groups of mountains, enclosing well-watered and fertile valleys and plains, and having a general direction from W. to E. The highest peaks are supposed to attain an elevation of nearly 15,000 feet; and although none of them reach the height of perpetual snow, some of their loftiest summits are covered with snow during the greater part of the year. Mount Miltsin, 27 miles S.E. of the city of Marocco, was ascertained by Captain Wash ington to be 11,400 feet high. The greatest heights are in^Marocco, from which point they appear to diminish in elevation as they extend towards the E. These mountains, except the loftier summits, are, for the most part, covered with thick forests of pine, oak, cork, white poplar, wild olive, and other trees. The inferior ranges seem to be principally composed of Secondary limestone, which, at a greater elevation, is succeeded by micaceous schist and quartz-rock ; and the higher chains are said to consist of granite, gneiss, mica-slate, and clay-slate. The Secondary and Tertiary formations are frequently disturbed and upraised by trap-rocks of comparatively modern date. Lead iron copper, antimony, sulphur, and rock-salt occur frequently ; and in the Marocco portion of the range gold and silver are said to exist, In the Algerian division are mines of copper, lead, silver, and antimony. The lion, hyena, boar, and bear are common throughout the moun tains. None of the rivers which take their rise in the sys tem are of any great importance. The Tafilet is absorbed in the sands ; the Tensift and Draa flow into the Atlantic; j and about five or six find their way to the Mediterranean. Dr Hooker has explored the botany of many parts of the range, and the travels of Rohlfs have added largely to our general knowledge of it.