514 BHOTAN. Chap. XXIX. 



From the sea-level to an elevation of 12,000 feet Sikkim 

 is covered with a dense forest, consisting of tall umbrageons 

 trees, often with dense grass jungle, and in other places 

 accompanied by a luxuriant undergrowth of shrubs. In the 

 tropical zone Myrtacece, Leguminosce, and tree-ferns are com- 

 mon, and the air is near saturation during a great part of the 

 year. Vacmiia are found at from 5000 to 8000, and snow 

 occasionally falls at 6000 feet. A sub-tropical vegetation 

 penetrates far into the interior along the banks of the great 

 rivers, and tree-ferns, rattans, plantains, and other tropical 

 plants are found at 5000 feet, in the Eatong valley.* 



I should conjecture that the extreme limit for the growi;li 

 of the hardier species of chinchona?, in Sikkim, will be found 

 where their constant companions the tree-ferns and Vaccinia 

 end, namely at 5000 feet ; and that the best sites for such 

 species as C. Calimya and C. succiruhra are about 1000 to 

 2000 feet lower, amidst the sub-tropical vegetation of the 

 valleys. 



Bhotan, which adjoins Sikkim on the east, is a mountainous 

 district of much the same character. In its western part the 

 mountain ranges are lofty and rugged, and the river-courses 

 very deep and generally narrow. The climate is equable, and 

 the humidity of the winter appears to increase in the part 

 adjoining Sikkim, The steepness of the mountains, and the 

 influence of the elevated mass of the Khassya hills to the 

 south, make the lower slopes, which skirt the plains of Assam, 

 drier than those more to the eastward. Deep narrow valleys 

 carry a tropical vegetation very far into the interior of 

 Bhotan, among lofty mountains capped with almost per- 

 petual snow. These attract to themselves so much of the 

 moisture of the atmosphere, that the bottoms of the valleys 

 are comparatively dry and bare of forest. The flora resembles 

 that of Sikkim."" 



* Flora ludica, i., p. 178. ' Ibid., i., p. 175. 



