58 STEPPE FAUNAS AND TEMPERATE 



wooded regions of China to the south-east by mountain 

 chains. Through the Dzungarian Gate this area, to 

 which the general name of Desert of Gobi or Shamo 

 may be given, is continuous with the extensive band of 

 steppes which runs through Russian Turkestan to the 

 Aral and Caspian seas, is continued through Southern 

 Russia in Europe into Hungary, and is bounded to the 

 south-west by the plateau of Persia. But uniform con- 

 ditions do not reign throughout this great area, which 

 shows many alternations of fertihty and aridity. Thus 

 the snows of the Pamirs water much of Russian Turke- 

 stan through the Amu Daria and the Syr Daria, and 

 this westerly region as a whole has a much milder 

 winter climate than the easterly region, permitting of 

 the extension into it of animals reaUy peculiar to the 

 southern steppe and desert regions, those characterized 

 by the absence of severe winter cold. 



Climatically, as we have seen, the general features of 

 the steppes of temperate Asia are the great range of 

 temperature, the hot summers and the bitterly cold 

 winters, and the small precipitation, which tends to 

 occur in late spring or early summer, giving a dry 

 winter and a dry summer and autumn, which makes 

 the growth of trees virtually impossible. The frequency 

 of dry east winds in winter is an important feature in 

 checking the growth of perennial plants, except such as 

 die down to the ground. As indications of the nature 

 of the climate, we may note that at Orenburg the 

 mean January temperature is 4° F., and the mean July 

 70° F., while the mean annual precipitation is only 17", 

 with a June maximum, but no absolutely dry month. 

 Further to the east much lower winter temperatures- 

 occur ; thus Sven Hedin found temperatures of — 17° F. 

 in the Tarim basin,"and the river here is frozen for three 



