ANNOTATIONS AND ADDITIONS. 109 



and by the Steppes between Barnaul and the Serpent Mountain and 

 the country on the east of the Caspian. Here Chenopodias, some 

 species of Salsola and Atriplex, Salicornias and Halimocnemis cras- 

 sifolia, (each species growing " socially/') form patches of vegetation 

 on the muddy ground. See Gbbel's Journey in the Steppes of the 

 South of Russia (Reise in die Steppe des siidlichen Russlands, 

 .1838, th. ii. s. 244 and 301). Of the 500 phanerogamous species 

 which Claus and Gbbel collected in. the Steppes, the Syrantheraa, the 

 Chenopodese, and the CruciferaD, were more numerous than the 

 grasses ; the latter being only -^yth of the whole, and the former |th 

 and ^th. In Germany, from the mixture of hill and plain districts, 

 the Glumaceae (i. e. the Graminese, CyperaeeaB, and Juncaceae col- 

 lectively) form |th ; the Synantherae or Compositae |th ; and the 

 Cruciferae T \th of all our German phanerogamia. In the most 

 northern parts of the flat Siberian lowlands, the fine map of Admi- 

 ral Wrangell shows that the extreme northern limit of tree and 

 shrub vegetation (Coniferae and Amentaceae) is, in the portion to- 

 wards the Behring's Straits side, in G7 lat. ; and more to the west, 

 towards the banks of the Lena, in 71, which is the parallel of the 

 north cape of Lapland. The plains which border the Icy Sea are the 

 domain of cryptogamous plants. They are called Tundras (Tuntur, in 

 Finnish) : they are swampy districts extending farther than the eye 

 can reach, partly covered with a thick carpet of Sphagnum palustre 

 and other mosses, and partly with a dry snow-white covering of Ceno- 

 myce rangiferina (Reindeer moss), Stereocaulon paschale, and other 

 lichens. Admiral Wrangell, in describing his perilous expedition to 

 the new Siberian islands so rich in fossil wood, says : " These Tun- 

 dras accompanied me to the extreme arctic coast. Their soil has 

 been frozen for thousands of years. In the dreary uniformity of 

 landscape, the eye of the traveller, surrounded by reindeer moss, 

 dwells with pleasure on the smallest patch of green turf showing 

 itself now and then on a moist spot." 



( 18 ) p. 30. t( The causes which lessen both heat and dry ness in the 

 New World." 



I have tried, to bring together in a brief and compendious manner 

 the various causes which produce greater moisture and a less degree 

 10 



