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sion, which might readily be marked upon any good map at home, and 

 easily be recognized by a good eye in the field. And a system of 

 division founded upon the river drainage was preferred to all others, as 

 on the whole most likely to give useful botanical results, and as falling 

 in with Mr. Watson's system of provinces, of which indeed it was the 

 carrying out into particulars. After some consideration, and some 

 changes, the county was divided into twelve districts, averaging about 

 fifty statute square miles each, and consisting as far as possible of the 

 basins, or definite portions of the basins, of the principal rivers. 



All former observations on the frequency of the more ordinary spe- 

 cies were now considered as relating exclusively to the home district ; 

 and for the others, when catalogues could not be obtained from resi- 

 dent correspondents, expeditions were undertaken to them for the 

 purpose of ascertaining their common, as well as rare productions. 

 As soon as the number on record in any district approached 400, 

 the still unobserved species which seemed likely to occur there were 

 formed into lists of desiderata. Some curious features, which had 

 formerly escaped notice, or were matters of mere surmise, now began 

 to come to light, or to receive confirmation. Digitalis, Conium, Po- 

 tentilla argentea, Artemisia vulgaris, Carex paniculata, and others 

 which the experience of the home district alone would have set down 

 as common, were now found to be either wholly wanting or very scarce 

 in some of the districts : while others, as Trifolium fragiferum, Ophrys 

 apifera, Carex axillaris, &c, which home experience had seemed to 

 prove rare, were found to be widely distributed over the county : and 

 scarcely a fourth part of the whole Flora was found to be so universally 

 distributed as to occur in every one of the twelve districts. Another 

 advantage of the plan was that the desire to obtain as complete a list 

 as possible for each of the districts induced repeated excursions into 

 most of them in succession ; whereby not only were their recorded 

 Floras increased, but new species and new stations for the rarer ones 

 were frequently brought to light : and that correspondents, having a 

 local interest in the reputation of their respective districts, were stimu- 

 lated to increase their diligence. And thus, though the more distant 

 districts could not be expected to be equally well explored with those 

 nearer home, the Flora of the county is at least in a great measure 

 rescued from the reproach which it would otherwise have been 

 susceptible of, and can no longer be charged with offering a single 

 brick as a specimen of the whole house. 



In fact, the plan of subdivision above detailed has been found to be 

 attended with so much advantage, that the adoption of one of a similar 



