Q4 INTRODUCTION. 
No decided lines of separation can be traced between these 
Types of Distribution. They may be said to pass gradually into 
each other; the distribution of some of the species presenting 
a character so intermediate, as to render the choice of type to 
express it either dubious or optional. Still, the differences be- 
tween them are real, inasmuch as a prevailing tendency to such 
peculiarities of distribution among the plants of this country has 
been made quite evident through the Cybele Britannica, and was 
also earlier shown, though perhaps less clearly shown, in the same 
Author's “Remarks on the Geographical Distribution of British 
Plants,” published so long back as 1836. The transition from one 
group or type into another, is gradually brought about through 
some species having less of the distinctive character of the group 
to which they must be assigned on the general view, and thus in 
so far partially resembling the plants of some other group also. 
Many of the species assigned to the British type, in becoming less 
plentiful towards the northern or southern extremities of the 
island, will thus approximate to the English or Scottish types. In 
like manner, some of those placed under the English type may be 
regarded as passing into the Germanic or Atlantic type by their 
lessened frequency in the westerly or easterly provinces of Eng- 
land. And between the Highland and Scottish types (or arctic 
and boreal types) the distinction is occasionally very slight indeed; 
certain species being assignable to either with almost equal fitness. 
Still, it is repeated, these geographic types do represent real 
peculiarities of distribution, thrown into combination according to 
some common points of similarity. They will now be briefly 
described, each in succession, simply as facts in nature, and 
apart from all the idle and hypothetical fancies which have been 
spuriously connected with them. 
1. The British Type.— In this group will be included those 
species which are found in all, or in nearly all, of the eighteen 
provinces before explained; and which, moreover, are not so 
exclusively prevalent in any particular portion of the island as to 
bring them clearly within one or other of the succeeding types. 
Some of them may be regarded as of universal occurrence in this 
