THE CLIMATAL DISTRIBUTION OF BRITISH PLANTS. 53 
shire—it extends up the hills to about goo feet, while at its 
northern limit it comprises only land quite near the sea 
level. Again, south of the Humber a great deal of the 
higher-land comes within it, for instance, belts round the 
higher hills of Derbyshire and Wales, and the summits of 
many lower hills in the South and West of England. 
Some of the plants which here have their lowest limit are 
of especial interest as forming a conspicuous part of the 
flora of the North Derbyshire hills and dales: among these 
are the beautiful Globe Flower (Tvollius Europeus), the 
Mountain Pansy (Viola lutea), The Jacob’s Ladder (Polemonium 
cevuleum), and the Mossy Saxifrage (Saxifraga hypnoides). 
The most interesting plant confined to this zone is the 
curious Lady’s Slipper Orchid (Cypripedium Calceolus), which 
is confined to a few localities in North West Yorkshire, 
Westmorland, and Durham. 
Watson’s 3rd zone, the Super-agravian, comprises, first, all 
the land at or near the sea-level north of the Firths of 
Forth and Clyde; secondly, a broad belt in the South of 
Scotland and North of England, extending as far south as 
the Peak, where this zone begins at about 1,000 feet and 
extends as high as 1,700 feet; thivdly, a considerable area in 
Wales; and, finally, the summits of Cawsand and Dunkerry 
Beacons. 
The difference between this zone and zone 2 is much 
more marked than that between zones 1 and 2, more than 
300 plants which are found in zone 2 being absent here, 
and in their place about 50 new comers appearing. The 
most interesting feature is, however, the large number of 
plants which here reach their highest limit. Of about 760 
species which inhabit this zone, nearly 500 are not found 
in any of the higher zones. 
The Arctic region consists entirely of mountains or high- 
lands. In England, south of the Humber, the higher 
plateaus and ridges of the Peak are the only hills which reach 
