EANGE OF PLANTS 437 



centre and migrating to any extent from one focus of greater 

 development. 



I do not think there is in the North any instance of the 

 floras of two such remote spots as Kerg. Land and Cape 

 Horn being identical. Two Floras appear in the Northern 

 Hemisphere, the American and the European. The former 

 is confined to the American Arctic shores and islands, the 

 latter to all Arctic Europe, Asia and Greenland : Western 

 Arctic American to the W. of the great chain of the Kocky 

 Mountains, and North of the Oregon Biver may also belong 

 to the European Flora and is likely to, but I have not 

 compared, having no materials in the Erebus. The abrupt 

 line of demarkation is most remarkable in Baffin's Bay and 

 Davis Straits, the most common European Heathers and 

 some other plants being found abundantly along the Eastern 

 shores and islands of those waters, but never on the Western. 

 Of course a multitude of plants are common to both Hemi- 

 spheres, which makes it in one sense the more remarkable 

 that two or three of the types of Northern European Botany 

 should not cross to the Westward of Longitude 60 W. 



I have been progressing with the Antarctic plants, using 

 yours, King's and my own at once, and each according 

 to the Nat. Ords., beginning with Banunculaceae, where 

 the value of every scrap tells better than it is possible to 

 suppose. The little Cardamine or Cress I prove, by com- 

 parison with about 50 states of it running through the whole 

 continent of S. America, to be the same as the most common 

 European weed, C. hirsuta. This is not wonderful, but it 

 is, that Winter's Bark, Drimys Winteri, should extend 

 through the whole continent of S. America and Mexico, from 

 25 N. to 56 S. It is true that the extreme states vary, 

 and apparently specifically, but take the regular series of 

 specimens, beginning with my own Cape Horn ones, your 

 and King's Fuegian, Bertero's and Bridge's and Cuming's 

 Chilian, the Brazilian ones of many collectors ; Peruvian 

 and Bolivian States from others ; and finally, end the list 

 with the Mexican, and no one (not even the most determined 

 species-monger) can make them specifically distinct. It 

 is further proved by the later Brazilian Botanical authors 

 considering their species the Chilian, and contemporaneous 

 Mexican writers, not aware of this last re-union, uniting 



VOL. I 2 F 



