HOOKER ON ARCTIC TLANT?. 213 



Straits. The shallowness of the ocean between America and Asia 

 north of lat. 60°, together with the identity of the vegetation in 

 the higher latitudes of these continents, suggests the probability 

 of the land having been continuous at no remote epoch. 



The number of phajnogamic plants hitherto found in Arctic 

 West America is 364 : — 



Monocotyledons - - 76 "1 __ , « »7 

 Dicotyledons - - - 288 / "~ ^ ' '^'^* 



The proportion of genera to species is 1:1-7. Of these 364 

 species, almost all but the littoral and purely Arctic species are 

 found in West-temperate North America or in the Rocky Moun- 

 tains, 26 in the Andes of Tropical or Sub-tropical America, and 

 37 in Temperate or Antarctic South America. Comparing this 

 flora with that of Temperate and Arctic Asia, I find that no less 

 than 320 species are found on the north-western shores and 

 islands of that continent, or in Siberia, many extending to the 

 Altai and the Himalaya. A comparison with Eastern Arctic 

 America shows that 281 are common to it, and 38 are found in 

 Temperate but not Arctic East America. [The list follows^ 

 page 266.] 



These, it will be seen, are for the most part North-temperate 

 plants, common in many parts of the globe, and which are only 

 excluded from Eastern Arctic America by the greater rigour of 

 its climate. 



The best marked European and Asiatic species that are not 

 found further east in Temperate or Arctic America are 18 in 

 number. [The list follows, page 267.] 



Hence it appears that of the 364 species found in Arctic West 

 America^ 319 inhabit East America (Arctic or Temperate, or 

 both), and 320 are natives of the Old World — a difference hardly 

 sufficient to establish a closer affinity of this flora with one con- 

 tinent rather than with the other. 



The species peculiar to this tract of land (Arctic West Ame- 

 rica) are : — 



Braya pilosa. Saussurea subsinuata, 



Saxifraga Richardsonii. Salix glacialis. 



Artemisia androsacea. 



The rarity of Monocotyledons, and especially of the glumaceous 

 orders, is almost as marked a feature of this as of the Asiatic 

 flora ; of the 138 Arctic species of GlumacecB, only 54 are natives 

 of West Arctic America. 



The materials for this flora are principally the plants of 

 Chamisso, collected during Kotzebue's voyage, and described by 

 himself and Schlechtendahl ; Lay and Collie's collections, de- 

 scribed in Beecher's voyage ; the " Flora B or eali- Americana " ; 

 and Seemann's plants, described in the "Botany of the Herald." 

 Most of the above collections are from Behring's Straits. For the 

 Arctic coast flora I am mainly indebted to Richardson's researches, 

 and to PuUen's and other collections enumerated by Seemann in 

 his account of the flora of Western Eskimo Land. For the 

 southern extension of the flora'_I have had recourse to the " Flora 



