152 A NATURALIST IN WESTERN CHINA 



ring in the actual bed of such streams. In many the waters 

 are actually boiling, and I have several times cooked eggs in 

 them. These hot springs are much resorted to by the people 

 of the surrounding regions for bathing purposes, the waters 

 being esteemed as a cure for rheumatism, skin affections, and 

 other complaints. 



Three large rivers, Tung, Yalung, and Dre, flow through 

 this borderland, mainly from north to south, as necessitated by 

 the direction of the mountain axes. These rivers have tribu- 

 taries in abundance, and the majority of them, draining from 

 eternal snows, carry down enormous quantities of water and 

 detritus. None of these rivers is navigable save for rafts, 

 specially constructed boats, or skin coracles, over very short 

 and interrupted stretches. Bridges and ferries are few, never- 

 theless the highways and by-ways of this region skirt the banks 

 of these rivers and their main tributaries. 



The valleys of all these streams, and for the purpose of 

 what follows the Min above Kuan Hsien may be included, are 

 deeply eroded, the waters flowing between steep slopes or pre- 

 cipices. These valleys are aU very similar, being narrow, shut 

 in by lofty treeless mountains, and all enjoy a much hotter, 

 drier climate than their altitude warrants. Long stretches 

 are very barren and desert-like, more especially when the out- 

 cropping rocks are solely granitic. Owing to this dry, hot 

 climate, interesting anomalies obtain in these valleys. At 

 Hokou, on the Yalung, maize can be cultivated up to nearly 

 9500 feet altitude, whereas at Tachienlu, in the same latitude 

 and 1000 feet less altitude, it is impossible to bring this cereal 

 to maturity. Green parrots {Palceornis derbyana salvadori) 

 occur as summer migrants in the valleys of the Yalung and 

 Drechu up to 10,000 feet altitude. Rock pigeons occur in 

 multitudes throughout all these valleys above 4000 feet altitude. 

 Monkeys also are common. The flora generally is specially 

 adapted to withstand drought, and is more closely allied to 

 that of the Yunnan plateaux than to the contiguous country. 

 Doubtless at one time the mountain-slopes flanking these 

 valleys were wooded, though it is improbable that the lower 

 slopes were ever heavily forested ; but such timber as grew 

 there has long since disappeared, and to-day these slopes are 



