its very shallow erosion furrows and beds it, however, seems to fall from north to south. On all sides, it is surrounded by mountains. Those to the south are comparatively low. Between the latter, there is, no doubt, a passage by which the watercourse of the valley pierces its way southwards. This would also be in perfect accordance with Deasy's map. For several days he travelled in a meridional valley which he calls Damtang-lungpa. The watercourse of our Camps CCCXXX and CCCXXXI, is obviously one of the uppermost feeders of this meridional valley, and somewhere in the eastern part of the arena plain, not far from Camp CCCXXXII, we must have crossed Deasy's route.
To the E. S. E., was the opening of the valley to which we steered. It seemed to lead to a very flat threshold beyond which, far away, a mountain was visible. This seemed to indicate comparatively level ground for a few days' march. The arena valley was about 1 o km. broad and 8 km. on our road. It would have been very comfortable for our march if it had not been snow-covered to nine tenths of its area. The snow lay one foot deep, and in erosion beds which we had to cross, two or three feet. Sometimes the surface of the snowdrifts was so wind-beaten, frozen and hard, that our animals could pass without breaking through. Grass was seen only at a place in the western part of the plain, which otherwise has only some moss and yapchan plants. Only antelopes were grazing, two wolves were seen ; of yaks and kyangs only the dung. Of human visits no sign, not even a path. Entering the valley on the east side of the plain, we very slowly ascended to the little threshold which is so flat that it is impossible to tell where it is situated. On its eastern side the slope is just as gradual to Camp CCCXXXII, where the vegetation was the same as hitherto, and the amount of snow not quite as great. From this camp, Pan. 415, Tab. 75, is drawn showing the valley to the N. 6 6° W. in the direction of the little threshold. Pan. 416, Tab. 75, is a view of the continuation of the valley to S. 68° E. the way we had to travel the next day.
It is a very characteristic and interesting feature that the latitudinal valleys are so well developed in this part of western Tibet as we had found on our crossing nearly the whole way from the Lake of Aksai-chin. Of course we had met some irregularities in this long distance, and we had had to cross two very high and several lower passes and thresholds, but this does not interfere with the fact that the mountain ranges in western Tibet follow the orographical laws so well known for the stretching of western Himalaya and western Kara-korum, and dictate the N. W.—S. E. running of the latitudinal valleys. Particularly from Shemen-tso our valley had been regular and typical. In one respect the latitudinal valleys of Western Tibet are, as a rule, very unlike those of Eastern Tibet, viz. that the former are much narrower as e. g. the valley of Camp CCCXXX. This, of course, simply depends upon the fact that the mountain ranges of Western Tibet, on account of
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