VII, FORMULA EXPLAINED. 67 
exclusive of others to which they may have been extended by 
human agency. If these latter are named, they are enclosed in 
the same manner as the provincial nos. in the line above. For 
denizens and colonists less strictness in this respect is unavoidable; 
none of their localities of course being clear from some degree 
of doubt or distrust; and thus only the most distrusted are left 
out or enclosed. The counties in which these plants become more 
evidently aliens or casuals, for instance, are either not taken into 
account at all, or else. are enclosed like the provincial nos. 
Usually, the citations of counties are so made as to include both 
the western and eastern sides of the island, so as to indicate also 
the longitude. Thus, “ Cornwall, Wight, Kent,” will not only 
show an area extending into the most southern counties, but will 
serve also to show an intermediate along with an extreme westerly 
and easterly extension. It has been found not so easy to adhere 
closely to this rule in citing counties for the northern limits ; 
although it is usually acted upon in cases where those limits 
would not appear to be unduly contracted by so doing. Botanists 
will scarcely require to be reminded, that the discovery of a new 
locality beyond the limitary lines specified, would in general be a 
more important fact in topographical botany, than would be the 
discovery of another locality within the limits specified. Besides, 
they may hold with some approach to certainty, that localities 
beyond the indicated limits truly are new additions to our reliable 
records, not simply repetitions of the old facts. 
The Third line indicates the zonal and altitudinal distribution. 
The Ascending or climatic zones in which the plant occurs, are 
first shown by citing their corresponding nos. The explanations 
about these zones were given on pages 14 to 21. Secondly, such 
notices of the range of altitude are added as can be compressed 
into the other portion of the line. The relation of plants to 
elevation was treated in full in the original Cybele Britannica ; 
and two linés of the formula there used were devoted to the indi- 
cations of upper and lower limits. The subject is too complex to 
permit of full and precise indications within the space that can be 
allotted to it in this Compendium. The citation of the zonal 
