GEOGRAPHICAL BOTANY. 405 



open, fluviatile valleys, the most thickly populated in 

 Peru, and is separated from that of the Puna by rocky 

 declivities ; rainy season, with frequent hail, from October 

 to February. During the winter months (also called 

 summer in the text) dry east winds prevail ; night frosts 

 set in after the end of the rainy season, and the Cerealia 

 are harvested. Mean temp, during the rainy season : of 

 the night = + 5'l, of the day = + 14'l ; during 

 the winter (March to September), of the night = 4'25, 

 at noon + 17'l. But great local differences occur in 

 the hot bottoms of those valleys which are sheltered from 

 the winds, where fruits of the south of Europe, as peach 

 trees, thrive, sometimes even at an altitude of more 

 than 10,000'; the principal cereal grain appears to be 

 maize. The slope of this region, which, like the former, 

 is destitute of woods, contains a profusion of Cacti, and 

 on the banks of the streams only we find woods of 8alix 

 Humboldtiana, 20' in height ; even European fruit trees 

 do not thrive when cultivated. In the valleys, however, 

 this region extends directly into the forest region, from 

 which it is also separated by a second Puna, i. e. by the 

 crest of the central Cordillera. 



c. Upper forest region or Ceja-region (from Ceja de la 

 Montague, i. e. the brow of the mountain) (8000' 5500'), 

 comprises the eastern slope of the internal Cordillera, and 

 its western slope in the north of Peru, with the longitudinal 

 valley of Huallaga. It consists of steep rocks and narrow, 

 wooded mountain-ridges. The climate is humid, cold, 

 and rough, with prevailing south winds. Towards evening 

 dense mists are formed, which during the night rest upon 

 the forests, and which the wind carries away with it from 

 the morning until the serene evening. These mists ex- 

 tend downwards as far as 6500', and often resolve them- 

 selves into very heavy showers. The differences in the 

 seasons are not mentioned ; the observations upon the 

 temperature are also incomplete. Low trees and shrubs 

 covered with mosses commence even at 9500', and 

 increase in size and strength as we ascend. Cerealia 



