Dictionary of Greek and Roman Geography/Apameia 2.
2. A city in Mesopotamia. Stephanus (s. v. Άπάμεια) describes Apameia as in the territory of the Meseni, " and surrounded by the Tigris, at which place, that is Apameia, or it may mean, in which country, Mesene, the Tigris is divided; on the right part there flows round a river Sellas, and on the left the Tigris, having the same name with the large one." It does not appear what writer he is copying ; but it may be Arnan. Pliny (vi. 27) says of the Tigris, "that around Apamcia, a town of Mesene, on this side of the Babylonian Seleuceia, 125 miles, the Tigris being divided into two channels, by one channel it flows to the south and to Seleuceia, washing all along Mesene; by the other channel, turning to the north at the bade of the same nation (Mesene), it divides the plains called Cauchae: when the waters have united again, the river is called Pasitigris." There was a place near Seleuce called Coche (Amm. Marc. xxiv. 5, and the notes of Valesius and Lindebrog); and the site of Seleuceia is below Bagdad. These are the only points in the description that are certain. It seems difficult to explain the passage of Pliny, or to determine the probable site of Apameia. It cannot be at Korno, as some suppose, where the Tigris and Euphrates meet, for both Stephanus and Pliny place Apameia at the point where the Tigris is divided. Pliny places Digba at Korna, "in ripa Tigris circa confluentes," — at the junction of the Tigris and the Euphrates.
But Pliny has another Apameia (vi. 31), which was surrounded by the Tigris; and he places it in Sittacene. It received the name of Apameia from the mother of Antiochus Soter, the first of the Seleucidae. Pliny adds: "haec dividitur Archoo," as if a stream flowed through the town. D'Anville (L'Euphrate et le Tigre) supposes that this Apameia was at the point where the Dijeil, now dry, branched off from the Tigris. D' Amille places the bifurcation near Samarrah, and there he puts Apameia. But Lynch (London Geog. Journal, vol. ix. p. 473) shows that the Dijeil branched off near Jibbarah, a little north of 34° N. lat. He supposes that the Dijeil once swept the end of the Median wall and flowed between it and Jibbarah, Somewhere, then, about this place Apameia may have been, for this point of the bifurcation of the Tigris is one degree of latitude N. of Seleuceia, and if the course of the river is measured, it will probably be not far from the distance which Pliny gives (cxxv. M. P.). The Mesene then was between the Tigris and the Dijeil; or a tract called Mesene is to be placed there. The name Sellas in Stephanus is probably corrupt, and the last editor of Stephanus may have done wrong in preferring it to the reading Delas, which is nearer the name Dijeil. Pliny may mean the same place Apameia in both the extracts that have been given; though some suppose that he is speaking of two different places.