IV. EXPLANATIONS, ETC. 819 



likewise, the Gentiana verna is deemed a boreal plant though unknown 

 in Scotland ; being limited to a few northern provinces of England, and 

 affecting their hilly portions chiefly or exclusively. 



Head-titles have been deemed unnecessary for the subdivisions of this 

 third list into subordinate groups. Tliey are obviously made in accord- 

 ance with the number of the most southerly province, or that in which 

 the plants are supposed to find their south limit. The figures for the 

 still more southern provinces are of course omitted; and the needless 

 repetition of dots instead is obviated by commencing the lines with the 

 higher figures or numbers. Counties are mentioned towards the end of 

 this list, as was done at the commencement of the austral list. 



This arrangement of the plants according to their latitudinal and 

 provincial areas has proved a difiicult and lime-consuming task to work 

 out. It is not here presented as one altogether satisfactory or finished ; 

 but is rather to be viewed as an inchoate attempt, to be rendered more 

 complete and correct with the future progress of knowledge. The result 

 is in effect a successive elimination from the total flora of Britain, first, 

 of all those species which apparently are unadapted to the more 

 northerly climates. From these the transition is gradually made to 

 those which are adapted to bear the whole climate of Britain, at least 

 near the coast-level ; being naturally distributed from one end of the 

 island to the other, more or less ihoroughly and completely. And 

 thirdly, come those which appear most adapted to the northern climate, 

 least adapted to the southern climate. 



It seems almost needless to explain, that the climatal adaptations 

 here suggested are simply inferences from the actual distribution of the 

 plants ; it being of course only this latter that is directly shown and 

 established by tracing the plants through provincial areas and latitu- 

 dinal ranges. But those botanists who may desire to know the leading 

 facts of species-distribution in this island, and are yet little acquainted 

 with that distribution, will readily acquire a considerable amount of 

 knowledge on this subject, by an occasional glance over the series of 

 names in this Section. It must be assumed that they are already fami- 

 liar with the plants enumerated by name. In addition, they will require 

 to learn the eighteen provinces by their names and numbers, and their 

 respective positions in the map. This fiimiliarity with the numbers and 

 positions duly attained, the horizontal distribution of any species is seen 

 at a glance liy the line of figures; attention being at the same time 



