1849.] excursion from Darjiling to Tongld, 439 



tiana and 2 Crawfurdice, 2 Arisaema, Anagallis, Ardrosael and Ajuga, 

 Disporum, and three Comallaricp, one with verticillate leaves, whose 

 root is another "Bikh," and considered very virulent. Graminice 

 were very few in number, but a large Car ex covered the ground, amongst 

 the bamboo. 



Still the absence or rarity of several very large natural families at 

 this elevation, which have numerous representatives at and much below 

 the same level in the Western Himalaya, indicates a certain peculiarity 

 in Sikkim. These are the following : — Ranuncidacece, Fumarice, Cru- 

 ciferce, Alsinece, Geranice, Leguminosce, Potentilla, Rosa, Epilobium, 

 Crassullacece, Saxifragece, Umbelliferce, Lonicera, Valerianece, Dipsacece, 

 various genera of Composite, Campamdacece, Lobeliacece, Gentiance, 

 Boraginece, Scrophdarinece, Primulacece, Graminece. 



All the above are genera of the north temperate and subarctic zones, 

 which seek a much higher level in Sikkim than in the Western Hima- 

 laya or Bhotan. The difference in this respect being very much 

 greater than the small disparity of latitude, will account for, or than 

 any (if there be any) difference of mean temperature, for the snow line 

 is certainly very little different here, from that of the N. W. Himalaya. 

 On the other hand, certain tropical genera are more abundant in the 

 temperate zone of the Sikkim mountains, and ascend much higher there, 

 than in the Western Himalaya. Of this fact I have cited conspicuous 

 examples in the palms, plantains and tree fern ascending to nearly 7000, 

 and in the presence of many other orders at great elevations, figs, 

 peppers, Lauri, &c. ; and to these could be added many others, none 

 more remarkable than Balanophora, of which there are several species 

 above 4, and even 6000 ft. one ascending to 8000. 



This ascent and prevalence of tropical species, is due to the uniform 

 humidity and the equability of the climate in this temperate zone, 

 and is perhaps the direct consequence of these conditions. An appli- 

 cation of the same laws accounts for the extension of similar features 

 (tropical) of vegetation so far beyond the tropical limit in the southern 

 ocean ; where various natural orders which do not cross the 30th and 

 40th parallel of N. Latitude, are extended to the 40th, 50th and 60th 

 in Tasmania, New Zealand, the so-called Antarctic Islands south of 

 that group ; and to Cape Horn itself in Fuegia. 



The forest region, encroaching so far upon, and in fact covering the 



