the vicinity of Nymphæum.[554] Claudius Cæsar informs us that, in the district of Arrene[555] it flows so near to the river Arsanias,[556] that when their waters swell they meet and flow together, but without, however, intermingling. For those of the Arsani, as he says, being lighter, float on the surface of the Tigris for a distance of nearly four miles, after which they separate, and the Arsanias flows into the Euphrates. The Tigris, after flowing through Armenia and receiving the well-known rivers Parthenias and Nicephorion, separates the Arabian Orei[557] from the Adiabeni, and then forms by its course, as previously mentioned, the country of Mesopotamia. After traversing the mountains of the Gordyæi,[558] it passes round Apamea,[559] a town of Mesene, one hundred and twenty-five miles on this side of Babylonian Seleucia, and then divides into two channels, one[560] of which runs southward, and flowing through Mesene, runs towards Seleucia, while the other takes a turn to the north and passes through the plains of the Cauchæ,[561] at the back of the district of Mesene. When the waters have reunited, the river assumes the name of Pasitigris. After this, it receives the Choaspes,[562] which comes from Media; and then, as we have already stated,[563] flowing between Seleucia and Ctesiphon, discharges itself into the Chaldæan Lakes, which it supplies for a distance of seventy miles. Escaping from them by a vast channel, it passes the city of Charax to the right, and empties itself into the Persian Sea, being ten miles in width at the mouth. Between the mouths of the two rivers Tigris and the Euphrates, the distance was formerly twenty-five, or, according to some writers, seven miles only, both of them being navigable to the sea. But the Orcheni and others who dwell on its banks, have long since dammed up the waters of the Euphrates for the purposes of irrigation, and it can only discharge itself into the sea by the aid of the Tigris. The country on the banks of the Tigris is called Parapotamia;[564] we have already made mention of Mesene, one of its districts. Dabithac[565] is a town there, adjoining to which is the district of Chalonitis, with the city of Ctesiphon,[566] famous, not only for its palm-groves, but for its olives, fruits, and other shrubs. Mount Zagrus[567] reaches as far as this district, and extends from Armenia between the Medi and the Adiabeni; above Parætacene and Persis. Chalonitis[568] is distant from Persis three hundred and eighty miles; some writers say that by the shortest route it is the same distance from Assyria and the Caspian Sea.