188 I'LORA INDICA. 



of Sikkinij except that Pinus excelsa is common, and the 

 larch is not found west of tlie Kosi. 



In the present state of our knowledge, it is not safe to in- 

 stitute a comparison between the alpine flora of Nipal and 

 that of Sikkim. Wallich's collections show us that the spe- 

 cies are on the whole the same. There is evidently a very 

 gradual change as we advance westward, partly owing, it may 

 be presumed, to increase of latitude and of summer drought, 

 and partly to more obscure causes which regulate the distri- 

 bution of plants. The elucidation of these will, we trust, be 

 one of the most important results of this work when com- 

 pleted, but with our pi'esent imperfect knowledge of species 

 the subject cannot be approached. The occurrence of Sibe- 

 rian types in small numbers among Wallich's alpine plants 

 shows that the climate to the North becomes at last arid, 

 exactly as elsewhere in the Himalaya. 



Though unable to indicate with any approach to precision 

 the number of Nipalese genera and species that are common 

 to the Eastern and Western Himalaya respectively, we have 

 collected a few instances of Himalayan species that we be- 

 lieve find their limits in Nipal. Of these the majority of the 

 Western Himalayan forms that advance no further east are 

 of European and Oriental genera or even species, as : — 



C&\.t\i& palustris. Eosa inoschata. 



Delpliinium vestitnm. Ulmus cmnpestris. 



Crattcgus Tyracmitlia. 



Others are more peculiarly Himalayan : — 



Chamaerops Martiana. PotentUIa atro-sangidnea. 



Quercus Janata. „ Nipalensis. 



Stranvsesia glaucescens. SpirEea Kamtschatica. 



Eosa Lyellii. 



Of these the Stranvasia, though not found further eastward 

 in the Himalaya, occurs in the Khasia, and perhaps the Cha- 

 marops may be the same as the Khasian species. The Spircsa 

 Kamtschatica is a native of Eastern Siberia. 



The number of Eastern Himalayan and Khasian forms that 



