1868.] HOOKER — ARCTIC FLORA. 349 



fiords are also drifted. It is important to bear in mind these 

 features of the two shores of Greenland and of Baffin's Bay and 

 Davis Straits, because they may in some degree explain their 

 differences of vegetation. There is also another difference between 

 the polar islands and Greenland, inasmuch as the former are for 

 the most part low, without mountains or extensive glaciers ; while 

 the latter is exceedingly mountainous, with valleys along the 

 shore terminating in glacier-headed fiords, and the coast is bound 

 by glaciers of prodigious extent from Melville Bay northwards to 

 Smith Sound. 



The isothermal lines in Greenland all follow one course, from 

 S.W. to N.E., running more parallel to one another in this 

 meridian than in any other. The isotherm of 32° passes through 

 the southern extremity of the peninsula, and that of 5° through 

 its north extreme at Smith Sound. The June isotherm of 41° 

 skirts its east coast, and that of 32° passes north of Disco ; the 

 June temperature of Disco is hence as low as that of the north of 

 Spitzbergen, of middle Nova Zembla, and of the extreme north of 

 Asia, and yet Disco contains quadruple their number of plants. 

 The autumn cold is very great ; the September isotherm of 32° 

 crossing the arctic circle on the west coast ; and to this the 

 scantiness of the flora may to some extent be attributed. 



The Arctic Greenland flora contains 206 species, according to 

 Lange's catalogue (in Rincke's ' Greenland ') ; or 207, according 

 to my materials (Monocot. 67, Dicot. 140=1 : 2-1) ; the pro- 

 portion of genera to species being 1:2. 



Of these 207 species the following 11 alone are not European : — 



Anemone Richardsonii (Asiatic). Potentilla tridentata (Labr. to Aileghanies). 



Turritis mollis (Asiatic). Saxifraga triscuspidata (do. to L. Superior). 



Vesicaria arctica (American only). Erigeron compositus (American only). 



Draba aurea (Rocky Mountains). Pedicularis euphrasioides (Asia). 



Hesperis Pallasii (Asia and America). Salix arctica (Asia). 

 Arenaria Grcenlandica (Labr. to U. S.). 



On the other hand, no less than 57 Arctic Greenland species 

 are absent in Arctic East America, and the following 36 Arctic 

 Europe and Greenland species are either absent in all parts of 

 Eastern Temperate America, or are extremely local there: — 



Arabis alpina (Labrador only). Stellaria cerastioides (absent). 



Lychnis alpina (do. and Newfoundland). Alchemilla alpina (do.). 



dioica (absent). vulgaris (Labrador only). 



Spergula nivalis (do.). Sibbaldia procumbens (Labr. to Wht. Mts.). 

 Arenaria uliginosa (do.). Rubus saxatilis (absent). 

 ciliata (do,). Potentilla verna (Labrador only). 



