DISTMB1 Tlo\ in PLANTS. 28] 



termediate portion of this continenl had been originally cover- 

 ed by the ocean; the eastern and western extremities, accord- 

 ing to the presenl system, would undoubtedly have ranked as 

 two botanical regions: but, the land being continuous, plants 

 have so intermingled that it is impossible to chaw a lin 

 distinction. 



As few plants arc diffused over the whole of the more \ 

 tensive of these regions, subregions maj be established, and 

 the principal rivers and chains of mountains should be em- 

 ployed for thai purpose a- the natural boundaries, each v, il>- 

 regiun containing many peculiar species. This has been 

 attempted in the second and third regions only. 



Tin- second region comprises four subregions: 



1. Flora Canadensis. All Canada, from the Atlantic to 

 the Pacific, and hounded south by the rivers Oregon, Mis- 

 souri, and St Lawrence. 



2. Flora of the United States. The country situated be- 

 tween the Atlantic and the Mississippi river. 



3. Flora Ludoviciana. The country situated between the 

 Mississippi and the northern Andes. 



i. Flora Californiana. The country situated between the 

 northern Audi- and the Pacific. 



The third region comprises six subregions: 



1. Flora Europea. The north of Europe and western Si- 

 beria, bounded easl by the river Fenisei, and south by the 

 chain of the Alps, of Caucasus, ^e. 



i. Flora Siberica. The country situated between the ¥e- 

 nesei and the Pacific. 



3. Flora Mediterranea. The south of Europe and north 



of Africa. 



4. Flora Persica. Persia, Syria and the north of Arabia, 

 bounded i asl by the Indus. 



.. Flora Thibetana. Thibet and the north of Hindostan. 



6. Flora Chinensis. China. Corea and the islands of .la- 

 pan. 



These four last do not corn -pond precisely with the threi 

 southern subregions of North America: as on the fortieth p 



\ in., in. — 1 i: 



