MESOPOTAMIA, the ancient name of the province of Diarbeck, in Asiatic Turkey. It is situated between the rivers Euphrates and Tigris, having Assyria on the east, Armenia on the north, Syria on the west, and Arabia Deserta, with Babylonia, on the south. The Hebrews called it Padan-aram, and Aram Naharaim, or Aram of the two rivers, because it was first peopled by Aram father of the
Mesopterycius, a term applied to such fishes as have only one back-fin, which is situated in the middle of the back.