in Ancient Geography, surnamed Babylonia, because situated on its confines, at the confluence of the Euphrates and the Tigris. Ptolemy places it in Mesopotamia. It is called also Seleucia ad Tigrim, being washed on the south by the Euphrates, and on the east by the Tigris. It is generally believed to have been built or enlarged by Seleucus Nicanor, master of the east after Alexander by means of which Babylon came to be deserted. It is said to have been originally called Coche, though others, as Arrian, distinguish it, as a village, from Seleucia; and, according to Zosimus, the ancient name of Seleucia was Zacharia. It is now called Bagdad. Long. 44. 21. E. Lat. 33. 10. N. There were many other cities of the same name, all built by Seleucus Nicanor.

SELEUCIDÆ, in Chronology. The era of the Seleucidæ, or the Syro-Macedonian era, is a computation of time, commencing from the establishment of the Seleucidæ, a race of Greek kings, who reigned as successors of Alexander the Great in Syria, as the Ptolemies did in Egypt. This era we find expressed in the books of the Maccabees, and on a great number of Greek medals struck by the cities of Syria. The Rabbins call it the era of contracts, and the Arabs therik dikarnain, or the era of the two horns. According to the best accounts, the first year of this era falls in the year 311 before Christ, being twelve years after Alexander's death.