INTRODUCTORY ESSAY. 181 



diminution of the humidity, the air being near saturation 

 during a great part of the year; but the decrease of tempe- 

 rature effects a marked change in the vegetation. Between 

 6000 and 8000 feet epiphytical orchids are extremely abun- 

 dant, and they do not entirely disappear till a height of 10,000 

 feet has been attained. Rhododendrons become abundant at 

 8000 feet, and from 10,000 to 14,000 feet they form in many 

 places the mass of the shrubby vegetation. Vaccinia, of which 

 there are ten species, almost all epiphytical, do not ascend so 

 high, and are most abundant at elevations of from 5000 to 

 8000 feet. 



The flora of the temperate zone presents a remarkable re- 

 semblance to that of Japan, in the mountains of which island 

 we have a very similar climate, both being cold and damp. 

 Helwingia, Aucuba, Stachyurus, and Enkianthus may be cited 

 as conspicuous instances of this similarity, which is the more 

 interesting because Japan is the nearest cold damp climate 

 to Silckim with whose vegetation we are acquainted. At 

 10,000 feet (on the summit of Tonglo) yew makes its appear- 

 ance, but no other conifer except those of the tropical belt is 

 found nearer the plains than the mountain Phalut, north of 

 Tonglo, on wliich Picea Webbiana is found, at levels above 

 10,000 feet. Abies Brunoniana is first met with at 9000 feet 

 in the Rangit valley, at Mon Lepcha, and A. Smithiana and 

 Brunoniana, and the larch, are found everywhere in the val- 

 leys of the Lachen and Lachung rivers, above 8000 feet. 

 The Pines are thus specifically the same as those of Bhotan, 

 except Pinus excelsa, which occurs nowhere in Sikkim. 



A subtropical vegetation penetrates far into the interior of 

 the country along the banks of the great rivers; rattans, 

 tree-ferns, plantains, screw-pines, and other tropical plants 

 occurring in the Ratong valley, almost at the foot of Kan- 

 chinjanga, and 5000 feet above the level of the sea. With 

 the pines, however, in the temperate zone, a very different 

 kind of vegetation presents itself. Here those great Eui-o- 

 pean families which are almost entirely wanting in the outer 



