342 THE CANADIAN NATURALIST. [June 



Further researches along the edge of the arctic circle would, 

 doubtless, add more Siberian species to this flora, as the examina- 

 tion of the north-east extreme would add American species, and 

 possibly lead to the flora of the country of the Tchutchis being 

 ranked with that of West America. 



The works which have yielded me most information regarding 

 this flora, are Ledebour's ' Flora Rossica,' and the valuable 

 memoirs of Bunge, C. A. Meyer, and Trautvetter, on the vegeta- 

 tion of the Taimyr and Boganida rivers; and on the plants of 

 Jenissei River in Von Midden dorff's Siberian ' Travels'. For their 

 southern extension Trautvetter and Meyer's ' Flora Ochotensis,' 

 also in Middendorff's 'Travels; ' Bunge's enumeration of North 

 China and Mongolian plants; Maximovicz's l Flora Amurensis ; ' 

 Asa Gray's paper on the botany of Japan (Mem. Amer. Acad. 

 N.S. vi.) ; Karelin and Kiriloff's enumeration of Soongarian 

 plants : Kegel, Bach, and Herder on the East Siberian and 

 Jakutsk collections of Paullowsky and Von Stubendorff. For 

 the Persian and Indian distribution, I have almost entirely 

 depended on the herbarium at Kew, and on Boissier's and 

 Bunge's numerous works. 



3. Arctic West America. — The district thus designated is 

 analogous in position, and to a considerable extent in climate, to 

 the Arctic European, but is much colder ; as is indicated both by 

 the mean temperature, and by the position of the June isotherm 

 of 41°, which makes an extraordinary bend to the south, nearly 

 to 52° N. lat., in the longitude of Behring's Straits. 



It extends from Cape Prince of Wales, on the east shore of 

 Behring's Straits, to the estuary of the Mackenzie river, and as a 

 whole it differs from the flora of the province to the eastward of it 

 by its far greater number both of European and Asiatic species, 

 by containing various Altai and Siberian plants which do not 

 reach so high a latitude in more western meridians, and by some 

 temperate plants peculiar to West America. This eastern boundary 

 is, however, quite an artificial one ; for a good many eastern plants 

 cross the Mackenzie and advance westwards to Point Barrow, but 

 which do not extend to Kotzebue Sound ; and a small colony of 

 Rocky Mountain plants also spread eastwards and westwards along 

 the shores of the Arctic Sea, which further tend to connect the 

 floras ; such are Aquilegia brevistyHs, Sisymbrium humile, 

 Ifutchinsia calycina, Heuchera Richardsonnii, Crepis nana, 

 Gentiana arctoph ila, Salix speciosa ; none of which are 



