It would be injustice to this gallant and long-suffering body of men not to present the reader with a minute description of the full length of their stupendous march. Up to the moment when the Greeks enter Karduchia, the line of march may be indicated upon evidence which, though not identifying special halting-places or localities, makes us certain that we cannot be far wrong on the whole. But after that moment, the evidence gradually disappears, and we are left with nothing more than a knowledge of the terminus, the general course, and a few negative conditions. Mr. Ainsworth has given, in his Book IV. (Travels in the Track of the Ten Thousand, p. 155 seq.) an interesting topographical comment on the march through Karduchia, and on the difficulties which the Greeks would have to surmount. He has farther shown what may have been their probable line of march through Karduchia; but the most important point which he has established here, seems to be the identity of the river Kentritês with the Buhtan-Chai, an eastern affluent of the Tigris—distinguishing it from the river of Bitlis on the west and the river Khabur on the south-east, with both of which it had been previously confounded (p. 167). The Buhtan-Chai falls into the Tigris at a village called Til, and “constitutes at the present day, a natural barrier between Kurdistan and Armenia” (p. 166). In this identification of the Kentritês with the Buhtan-Chai, Professor Koch agrees (Zug der Zehn Tausend, p. 78). If the Greeks crossed the Kentritês near its confluence with the Tigris, they would march up its right bank in one day to a situation near the modern town of Sert (Mr. Ainsworth thinks), though Xenophon takes no notice of the river of Bitlis, which nevertheless they must have passed. Their next two days of march, assuming a direction nearly north, would carry them (as Xenophon states, iv. 4, 2) beyond the sources of the Tigris; that is, “beyond the headwaters of the eastern tributaries to the Tigris.” Three days of additional march brought them to the river Teleboas—“of no great size, but beautiful” (iv. 4, 4). There appear sufficient reasons to identify this river with the Kara-Su or Black River, which flows through the valley or plain of Mush into the Murad or Eastern Euphrates (Ainsworth, p. 172; Ritter, Erdkunde, part x. s. 37. p. 682). Though Kinneir (Journey through Asia Minor and Kurdistan, 1818, p. 484), Rennell (Illustrations of the Expedition of Cyrus, p. 207) and Bell (System of Geography, iv. p. 140) identify it with the Ak-Su or river of Mush—this, according to Ainsworth, “is only a small tributary to the Kara-Su, which is the great river of the plain and district.”