244 
Oscar Drude. 
attempting to explain the striking absence of characteristic species 
of the various plant-associations. 
Arctic-Alpine Element. 
The distribution of the arctic-alpine element through Great 
Britain is also of very great interest, both on account of the low 
altitude of the stations of many species and of their concentration 
in definite parts of the country. The very useful tables published 
by E. Warming 1 on the Flora of Greenland, Iceland and the Faroes 
in comparison with North America, North and Mid-Europe and 
Siberia, furnish a basis for my calculations. Of the very great 
number of northern species occurring in the British Isles, forty-four 
are confined, within the British Isles, to the higher mountains: of 
these, nine are absent from the mid-European mountains (Sudetes, 
Hercynia, etc.) and from the Alps, and are in this sense arctic, e.g., 
Poa arctica (flexuosa ) and Alopecurus alpinus. But of the much 
greater group of British species which are scattered through the 
hills and moors of the islands, (such as Dryas, Primula farinosa, 
Selaginella spinul&sa, Pinguicula, etc., etc.) fourteen are likewise 
absent from the “ arctic ” areas of mid-Germany and from the 
German Alps, e.g., Aim alpina, Carex pulla ( saxatilis ), C. binervis, 
C. alpicola. The stations of these species, both of those occurring 
in, and of those absent from mid-Europe, are very variously scattered 
in Great Britain, much more so than in Germany, where they 
either inhabit the line of retreat of the Baltic ice from East Prussia 
to Holstein ; or moors on the old terminal moraines, for instance 
in Silesia and in Upper Bavaria; or, and mainly, the moors lying 
in the depressions of the mountains as well as in mountain ravines, 
on mountain rocks, etc. (Gratformationen) 2 above the tree-limit. 
The British stations fall into four main regions of the British 
Isles:— 
1. Wales. 
2. Cumberland, Westmoreland, N.W. Yorkshire, etc. 
3. The Grampians from Ben Lawers northwards. 
4. The scattered hill and mountain chains of West Ireland, 
especially round Galway Bay, in West Galway, Mayo 
and Sligo. It is of great interest that special species 
occur in each of these counties and that, as it seems 
to me, the species of phytogeographical interest having 
a distribution through all of them are very few. 
' Vidensk. Meddel. fra den naturhist. Forening: Kjobcnhavn, 
27 Jan. 188 : especially p. 45. 
* cf. W. G. Smith. “ Types of British Vegetation,” Chap. XII. 
and the literature there cited. 
