28 INTRODUCTION. 
and quite boreal area. Goodyera repens and Corallorhiza innata 
are also very partial, though less exclusively boreal. Primula 
farinosa and Sawifraga Hirculus may be cited as examples of the 
Intermediate type, characterised by a comparatively early limit 
northward. More characteristic examples of the Scottish type 
may be mentioned in Empetrum nigrum, Rubus saxatalis, Trol- 
lius europaeus, Geranium sylvaticum, Trientalis europea, Ligus- 
ticum scoticum, and Mertensia maritima. 
4. The Highland Type.— This may be considered the boreal 
flora in a more intense degree, as respects climate, than that of 
the Scottish type. The species referred hereto are distinguished 
from those of the Scottish type by being more especially limited to 
the mountains or their immediate vicinity. Some of them are 
wholly confined to the higher mountains, and never descend 
within the agrarian region; these bemg the ‘aretics,’ less appro- 
priately called ‘alpines.’ Others, though prevalent on the 
mountains, do descend also into their glens and valleys quite 
within the agrarian region. And others, again, may occasionally 
be seen outside the mountainous tracts, particularly along the 
courses of rivers which are fed by the mountain streams, or even 
upon the rocks of the seacoast. As a group, these plants are 
either restricted to the mountains or very decidedly more pre- 
valent there. Several of them, more especially the true arctics, 
are strictly peculiar to the Highland mountains; while others 
occur also on the hills of England and Wales, though less plenti- 
fully there than in the Highland provinces of Scotland. The 
name chosen for the type intimates their most appropriate habitat, 
allhough some of them do likewise find a suitable climate on the 
mountains of England or Wales. As examples of thoroughly 
Highland plants, such as do not occur in any province southward 
of the Highlands, we may cite «lzalea (Loiseleuria) procumbens, 
Cherleria sedoides, Veronica alpina, Alopecurus alpinus, Phlewin 
alpinum, Juncus trifidus, Sibbaldia procumbens, Erigeron alpinus, 
and Gentiana nivalis. And as examples of other species which 
occur also on the more southern mountains, and mostly descend 
lower than the preceding on the mountains of the Highland 
