ALPINE ZONES. 87 



white, and lilac rhododendra and Caragana j2idahi, 

 widi an occasional patch of bright red flowers. But 

 this does not last long. In July the rhododendra 

 and Caragana jubata cease blooming, and early in 

 August the morning frosts nip many of the herbs. 



The luxuriance of the alpine meadows is limited 

 to an elevation of 12,000 feet. The temperature 

 above this is too cold, and winds and storms of too 

 frequent occurrence, to allow of the development of 

 vegetation, which becomes more stunted the higher 

 we ascend, until it disappears altogether, and nothing 

 is left but bare rocks, with an occasional patch of 

 moss and lichen. Here the scientific observer may 

 find an admirable illustration of the wasting, irresis- 

 tible power of time, as it gradually wears down 

 the hardest rocks and reduces to insignificance the 

 loftiest cliffs. 



Here, too, amid the loose dcbj'is, springs take 

 their rise, at first trickling in feeble runnels, half 

 hidden beneath the stones, soon to unite with other 

 streams and descend in torrents down the rocky 

 valleys. 



As reo-ards fauna that of the Kan-su mountains 



о 



is richest in birds ; of mammals we only found 

 eighteen kinds, and fish and reptiles were very 

 scarce. The small number of insects and almost 

 entire absence of reptiles is due to the unfavourable 

 climate. 



The mammals belong exclusively to three orders, 

 carnivora, rodents, and ruminants. We did not see 

 a single specimen of the Insectivora or Cheiroptera. 



