Reaction and Succession in Relation to the Plant Covering. 409 
a marked feature. Robert Smith describing the fixed dunes near Edinburgh 
mentions the occurrence of Thalictrum minus, Anthyllis Vulneraria, 
Astragalus danicus, A. Glycyphyllos, and Gentiana A marella (Scottish 
Geog. Mag., vol. xvi, pp. 385-416, 1900). The list given by W. G. Smith 
for the dunes on the coast of Fife includes Astragahts danicus, Ononis 
repens, Linum cdtharticum, Trifolium procumbens , Medicago lupuhna, Galium 
verum , Gentiana campestris, G. A marella, Thymus serpyllum and Koelena 
cristata (Scottish Geog. Mag., vol. xxi, pp. 70-1, 1905). Moss, describing 
the dunes of Somerset (Journ. Roy. Geog. Soc., pp. 8-17, 1907), enumerates 
several dune species which attain their greatest abundance on chalky soils, 
of which Iris foetidissima, Carlina vulgaris, Anthyllis Vulneraria, and Inula 
Cbnyza are perhaps the most noteworthy. In ‘ Types of British Vegetation ’ 
Anthyllis Vulneraria, Chlora perfoliata, Gentiana campestris, G. baltica, 
Epipactis latifolia, and Orchis pyramidalis are mentioned as occurring on 
the Lancashire dunes. 
In Ireland the same feature holds. Colgan and Scully in the ‘ Cybele 
Hibernica ’ (2nd ed., 1898) cite many species as calcicolous in that country, 
of which nine are mentioned as occurring on sand dunes. These are Arabis 
hirsuta, Viola hirsuta, Orchis pyramidalis, Ophrys apifera, Asperula cynan- 
chica, Carlina vidgaris, Leontodon hirtus, Gentiana verna, and Clematis 
Vitalba. 
As might be expected this feature extends also to the Cryptogamic 
flora, and Watson (Journal of Ecology, pp. 126-42) cites Barbula tophacea, 
T richostomum crispulum, Camptothecium lutescens, Pellia fabbroniana, Preis- 
sia quadrata, Lophozia badensis, and Scapania aspera, as species whose 
occurrence on dunes is determined by the presence of comminuted shells. 
On the Continent the same feature is strikingly exhibited. Massart 
(‘ Essai de Geographic botanique,’ pp. 390-1, 1907) cites no less than twenty 
species which in Belgium are practically confined to dunes and calcareous 
soils. Of the total of'117 flowering plants cited by Abromeit ( £ Handbuch 
des deutschen Diinenbaues ’, Berlin, j 900) as present on German dunes 
some 19 specimens are more or less marked calcicoles. The same feature 
in another field is exemplified by the occurrence of the calcicole snail, 
Cyclostoma elegans, on sand dunes (cf. A. E. Boycott, Proc. Malac. Soc., 
vol. xiv, p. 128, 1921). 
At the other extreme the oldest dunes present, as we have seen, an 
almost entire absence of carbonates, and it is associated with this condition 
and a high acidity that P olypodium vulgare is met with in our area on the 
Long Hills, whilst Pteris and Athyrium occur on the Hood. 
On other systems these oldest phases of leached dune soils are marked 
by the presence of Ca'lluna vulgaris and other ericaceous plants. Any 
factor tending to accelerate leaching will naturally favour the colonization 
of ‘ calcifuge ’ plants. As the writer has pointed out, in relation, particu- 
