numerous all the way to the Panggong-tso. From higher points of vantage you can often count whole series of them, especially towards the north. From the above table it is however clear, that the three ranges which I consider to belong to the Tang-la system are the loftiest, and that absolutely the loftiest of all is the middle one, Tang-la II, which reaches a mean altitude of 5453 m. From this sublime elevation the ranges decrease in altitude both southwards and northwards, the only exception being the Arka-tagh, in which the altitude again increases. But the highest Arka-tagh range is nearly 200 m. lower than the highest Tang-la range. And precisely the same observations hold good of the latitudinal valleys: the three that lie nearest to the Tang-la ranges are the highest, the absolutely highest being the middle one at an elevation of 5093 m.