I 

 18 INTRODUCTORY EXPLANATIONS. 



rarely be errors of any material consequence to the subject 

 under consideration. 



Before adverting to another and different manner of di- 

 viding the botanical sm-face, the uses of these " Provinces " 

 may be shortly recapitulated. First, they afford a method 

 for showing the areas of plants, as facts in nature, indepen- 

 dently of all theoretical explanations and reasons. Se- 

 condly, they may be taken as a primaiy step towai'ds a 

 census of the species, in respect of then- comparative fre- 

 quency ; those most vridely and generally distributed, even 

 in large spaces, being usually also the most common species. 

 With increasing knowledge, the census will probably be 

 fomided on comities or smaller sections ; though this degree 

 of exactness cannot be perfectly reached at present. 

 Tliirdly, so far as it is shown, the distribution of the spe- 

 cies will be shown with greater comparative accuracy ; be- 

 cause our lists for provinces can be made much more frill 

 and accurate, than would be the case with county lists of 

 species, or lists for other smaller sections. Fourthly, much 

 cu'cumlocution and tedious enumeration of names may be 

 avoided, through referring to the distribution of species by 

 few provinces, rather than by many counties. But, fifthly, 

 it is to be remembered that these provinces are only arbi- 

 trary sections, adopted for convenience in description and 

 reference, instead of counties. So far as they do cor- 

 respond with peculiarities in the physical geogi'aphy of Bri- 

 tain, it is an advantageous circumstance ; although such a 

 coiTespondence is not necessary to their object or use. The 

 divisions next to come under consideration, on the con- 

 trary, are natm-al ; inasmuch as they will be traced in cor- 

 respondence with the actual distribution of plants, and 

 without reference to political or other conventional boun- 

 daries. 



