340 THE CANADIAN NATURALIST. [June 



x\ndersson, Nylander, Hartmann, Lindblom, Wahlberg, Blytt, 

 C. Martins, Ruprecht, and Schrenk. 



For Spitzbergen plants I have depended on Hooker's enumera- 

 tion of the Spitzbergen collections made during Parry's attempt 

 to reach the north pole, Capt. Sabine's collection made in the 

 same island, and on Lindblom and Beilschmied's ' Flora von 

 Spitzbergen' (Regensburg, Flora, 1842). 



For the southern distribution of the Arctic European plants, I 

 have further consulted Nyman's excellent ' Sylloge,' Ledebour's 

 ' Flora Rossica,' Grisebach's l Flora Rumelica, ' Grenier and 

 Godron's 'Flore de France,' Parlatore's 'Flora Italiana,' Koch's 

 ' Synopsis Florae Germanise,' Munby's ' Catalogue of Algerian 

 Plants,' A. Richard's of those of Abyssinia, Visiani's ' Flora 

 Dalmatica,' Delile's ' Flora iEgyptiaca,' Boissier's noble ' Voyage 

 Botanique dans l'Espagne,' and Tchihatcheff's 'Asia Minor,' 

 besides numerous local floras of the Mediterranean region, 

 Madeira, the Azores, and Canaries. 



2. Arctic Asia. — This, which for its extent, contains by far 

 the poorest flora of any on the globe, reaches from the Gulf of 

 Obi eastwards to Behring's Straits, where it merges into the West 

 iVmerican. The climate is marked by excessive mean cold ; at 

 the Obi the isotherm of 18° cuts the arctic circle in its S.E. 

 course, and at the eastern extremity of the province the isotherm 

 of 20° cuts the same circle, while the centre part of the district is 

 all north of the isotherm of 9°. The whole of the district is hence 

 far north of the isotherm of 32°, which descends to 52° N. lat. in 

 its middle longitude. The extremes of temperature are also very 

 great ; the June isotherm of 41 G ascending eastward through its 

 western half to the Polar Sea, whilst the September isotherm of 

 41° descends nearly to 6° N. lat, ; whence the low autumn tempera- 

 ture must present an almost insuperable obstacle to the ripening 

 of seeds within this segment of the polar circle. 



The warming influence of the Atlantic currents being felt no 

 further east than the Obi, and the summer desiccation of the vast 

 Asiatic continent, combine to render the climate of this region one 

 of excessive drought as well as cold ; whence it is in all ways 

 most unfavourable to every kind of vegetation. 



The total number of species hitherto recorded from this area 

 is 233 (Monocotyledons, 42 ; Dicotyledons, 191 = 1 : 4-5.) The 

 proportion of genera to species is 1 : 2. Of the 233 species, 217 

 inhabit Siberia as far south as the Altai, or Japan, etc. ; 104 



