Professor Koch, whose personal researches in and around Armenia give to his opinion the highest authority, follows Mr. Ainsworth in identifying the Teleboas with the Kara-Su. He supposes, however, that the Greeks crossed the Kentritês, not near its confluence with the Tigris, but considerably higher up, near the town of Sert or Sort. From hence he supposes that they marched nearly north-east in the modern road from Sert to Bitlis, thus getting round the head or near the head of the river called Bitlis-Su, which is one of the eastern affluents to the Tigris (falling first into the Buhtan-Chai), and which Xenophon took for the Tigris itself. They then marched farther, in a line not far distant from the Lake of Van, over the saddle which separates that lake from the lofty mountain Ali-Dagh. This saddle is the water-shed which separates the affluents to the Tigris from those to the Eastern Euphrates, of which latter the Teleboas or Kara-Su is one (Koch, Zug der Zehn Tausend, p. 82-84). After the river Teleboas, there seems no one point in the march which can be identified with anything approaching to certainty. Nor have we any means even of determining the general line of route, apart from specific places, which they followed from the river Teleboas to Trebizond. Their first object was to reach and cross the Eastern Euphrates. They would of course cross at the nearest point where they could find a ford. But how low down its course does the river continue to be fordable, in mid-winter, with snow on the ground? Here professor Koch differs from Mr. Ainsworth and colonel Chesney. He affirms that the river would be fordable a little above its confluence with the Tscharbahur, about latitude 39° 3′. According to Mr. Ainsworth, it would not be fordable below the confluence with the river of Khanus (Khinnis). Koch’s authority, as the most recent and systematic investigator of these regions, seems preferable, especially as it puts the Greeks nearly in the road now travelled over from Mush to Erzerum, which is said to be the only pass over the mountains open throughout all the winter, passing by Khinnis and Koili; see Ritter, Erdkunde, x. p. 387. Xenophon mentions a warm spring, which the army passed by during the third or fourth day after crossing the Euphrates (Anab. iv, 5, 15). Professor Koch believes himself to have identified this warm spring—the only one, as he states (p. 90-93), south of the range of mountains called the Bingöldagh—in the district called Wardo, near the village of Bashkan.