now the Apennine, a mountain, or ridge of mountains, running through the middle of Italy, from north-west to south-west, in the form of a crescent (Pliny); beginning at the Alps in Liguria, or the Riviera di Genoa, and terminating at the Strait of Messana, or at Reggio, and the promontory Leucopetra, and separating, as by a back or ridge, the Adriatic from the Tuscan Sea. (Pliny, Strabo, Ptolemy, Polybius, Vitruvius.) See ITALY.