DR, HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 267 
The best marked European and Asiatic species that are not found further east in 
Temperate or Arctic America are the following : 
Anemone narcissiflora. Spiraea chamaedrifolia. A triplex littoralis. 
Ranunculus Pallasii. Pyrethrum bipinnatum. Pinus cembra. 
Aconitum Napellus. Gentiana prostrata. Carex Norwegica. 
Parrya macrocarpa. Eritrichium aretioides. Deyeuxia strigosa. 
Dianthus alpinus. Pedicularis verticillata. Langsdorffii. 
Cerastiura vulgatum. Primula nivalis. Colpodium fulvum. 
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 continent 
rather than with the other. 
The species peculiar to this tract of land are : 
Braya pilosa. Artemisia androsacea. Salix glacialis. 
Saxifraga Richardsoni. Saussurea subsinuata. 
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 Glumacea 
only 54 are natives of West Arctic America. 
The materials for this flora are principally the plants of Chamisso, collected during 
Kotzehue's voyage, and described by himself and Schlechtendahl ; Lay and Collie's col- 
lections, described in Beechey'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. Tor the arctic coast flora I am mainly indebted to Richardson's 
researches, and to Pullen'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 Boreali- Americana ; ' Ledebour's 'Flora Rossica,' which includes 
the Sitcha plants ; the American floras of Nuttall, Pursh, Torrey, Gray, &c. ; and to the 
collections of Drs. Lyall and Wood formed in Vancouver's Island and British Columbia ; 
for the Californian, Mexican, and Cordillera floras generally, to the herbarium at Kew, 
the works above mentioned, and the various memoirs of Torrey and of Gray on the plants 
of the American Surveying Expeditions. 
4. Arctic East America (exclusive of Greenland).-^ tract of land is analogous to 
the Arctic Asiatic in many respects of position and climate, but is very much richer 
species. It extends from the estuary of the Mackenzie River to Baffin's Bay 
flora differs from that of the western part of the continent, both in the characters men- 
tioned in the notice of that province, and in possessing more East American species. 
The western boundary of this province is an artificial one ; the eastern is very natural, 
both botanieally and geographically ; for Baffin's Bay and Davis' Straits (unlike Behring s 
Strait) have very deep water and different floras on their opposite shores. 
The arctic circle is crossed in the longitude of the Mackenzie River by the isotherm ot 
and 
12°, which thence trends south-eastward to the middle of Hudson's Bay ; and in the long 
tude of Davis' Straits it is crossed by the isotherm of 18i°. The June isotherm of 4 
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