INTRODUCTORY EXPLANATIONS. 37 



Alchemilla alpina, Saxifi-aga stellaris, Oxyria rcnifoimis, 

 Polygonum viviparum, &c. &c. 



The question may hence be asked by readers, ' why the 

 tenn arctic is now employed for the regions and zones, 

 instead of the more familiar term alpine ; this latter de- 

 signation having been adopted in the author's earlier writ- 

 ings on the distribution of plants ? ' Two considerations 

 induce to the change of term. First, the word alpine is in 

 common use to express momitain plants, without reference 

 to their positions above or within the limits of cultivation ; 

 and it has thus a different and less precise signification 

 than the word arctic, as here applied and restricted. Se- 

 condly, the flora of all our mountains, above the limit of 

 cultivation, has much closer affinity with that seen north- 

 ward of the British islands, than it has with that of the Alps 

 of middle Europe : it is, for example, much more like the 

 flora of Lapland than the flora of Switzerland. 



We have next to sub-divide the Agrarian Region into 

 zones ; and for these also we may use the same terms as 

 before, prefixed to the name of the region, aud say an 

 Infer -agrarian, Mid- agrarian, and Super -agrarian zone. 

 But it will be found impracticable to define and distinguish 

 these agrarian zones by the presence or absence of single 

 species, as may usually be done in the arctic zones. Com- 

 paring a flora of one of the south-eastern provinces of 

 England with a flora of the Highland valleys, or of the 

 plains near the north coast of Scotland, the dissimilarities 

 would be fomid strongly marked, both in the species and 

 in their compaiative numbers ; and an intermediate tract, 

 between these two extremities of the agrarian region, would 

 be sufficiently well characterised by its own disthictive 

 features, taken in the aggi-egate. The chfficulty is always 

 renewed when wc; eudeavom- to divide natmal gradations 

 by abru])t lines, and to lay down distinctions which rest 



