SELEUCIDÆ, in chronology. Æra of the Seleucidae, or the Syro-Macedonian æra, is a computation of time, commencing from the establishment of the Seleucidae, a race of Greek kings, who reigned as successors of Alexander the Great, in Syria, as the Ptolemies did in Egypt. This æra we find expressed in the book of the Maccabees, and on a great number of Greek medals struck by the cities of Syria, &c. The Rabbins call it the æra of contracts; and the Arabs, tharik dilkarnain, that is, the "æra of the two horns." According to the best accounts, the first year of this æra falls in the year 311 B. C. being 12 years after Alexander's death.