belong more appropriately to the mountainous country south of the Kara-koschun. But the procedure is quite justified, if we confine our attention to the fact that both pairs of ranges are border-ranges.
The members of the Pjevtsoff expedition made excursions from Kara-saj up on the Tibetan plateau and crossed over the southern main range of the Kwen-lun by an unnamed pass with an altitude of 5058 m., situated immediately south of Dasch-köl; the lower range is there cut through by the Bostan-toghrak. The upper range was also crossed somewhat farther west by a pass of 5274 m. immediately south of Hangeit-köl. According to Bogdanovitsch the westward continuation of the range that lies south of the Dasch-köl is called the »Usu-tagh», probably a corruption of Ustun-tagh, »the Upper Mountains». When travelling south-west from Karasaj Deasy crossed over the pass of Atisch (5030 ni.), situated in a latitudinal valley between the Upper and the Lower Astin-tagh and not far from Schor-köl, and due south from Pulur he mentions the pass of At-to (5060 ni.), which appears to belong to the upper main range. The lakes Schor-köl, Hangeit-köl, and Dasch-köl are clearly situated in the big latitudinal valley between the two main ranges. And it is an equally indubitable fact, that both these ranges are continued westwards by the two ranges in which are situated the pass of Suget-davan and the pass of Sandschu-davan.
Whatever may be the real facts with regard to the ranges in the vicinity of Tokus-davan, this much is at any rate certain, that in precisely that region and for some distance farther west the two main ranges of the Kwen-lun system break up into several chains that diverge like the fingers of the human hand. Nevertheless the orographical relations here, at the western margin of the part of Tibet which lies north of the Arka-tagh, are far from being clear. According to Bogdanovitsch, the various mountain sections Tokus-davan, Musluk (with the pass of the sanie name at an alt of 4710 m.), the Moskovskij range, and the Tschimen-tagh form properly one single long-extended range, in which is also situated Preschevalskij's Mt Kreml. I crossed over this identical system on 6th October 1900 by a pass (5143 m.) north-west of the Atschik-köl. Possibly Bogdanovitsch's conception is on the whole correct, although to nie it appears more probable that the range which lies north of the Atschik-köl basin dwindles away entirely towards the east, and that the Kaltaalaghan and Tschimen-tagh merge westwards into the parallel ranges that lie north of the Tokus-davan and Musluk-tagh. But the orographical relations of this region can only be cleared up by detailed study on the spot ; the data which we as yet possess are too few to allow of safe conclusions being drawn.
The section of the Astin-tagh that is situated between the Tschertschen-darja and the Dschahan-saj is also but little known. In this stretch the system has been crossed at only one point, namely by myself in 1901, when I used the gorge of the Tscharklik-su. We may however assume that the Astin-tagh consists there, as it does farther east, of two parallel ranges, and of these the lower range is pierced by the river just mentioned, while the upper range is crossed by an unnamed pass at an altitude of 2944 m. The pass of Jaman-davan (3136 m.), on the other hand, is situated in a secondary spur. In the mountainous country south of the source-region of the Tscharklik-su I crossed over several other passes, most of them of a secondary
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