INTRODUCTION. xli 
beech wood of even moderate dimensions to be found in the 
district.” He notes that some beeches to the east of Alfred’s 
Tower are of considerable dimensions, “even here, however, 
the occurrence of the beeches, old as they undoubtedly are, in 
straight rows, suggests artificial planting.’ The typical 
molluscan association of these woods is the following : 
Clausilia laminata, Montagu (dominant): with 
Limax arborum, Bouchard-Chantereaux. 
Vitrina pellucida, Miiller. 
Vitrea alliaria, Miller. 
Vitrea nitidula, Draparnaud. 
Vitrea pura, Alder. 
Hygromia hispida, Linné. 
Hygromia rufescens, Pennant. 
Cochlicopa lubrica, Miiller. 
Ena obscura, Miiller (abundant). 
Clausilia bidentata, Strém. (abundant). 
There is a very meagre molluscan fauna on the uncultivated 
grass-lands and heath pastures of the whole of the sandstone area. 
The upland heath moors at Blackdown, on the Quantocks, and 
on Exmoor, are large tracts, with the three species of heather, 
Calluna vulgaris, Hull; Erica tetralix, Linné; and Erica 
cinerea, Linné, the dominant plants; Vaccinium myrtillus, 
Linné; Molinia cerulea, Moench; Agrostis, spp.; and Pteris 
aquilina, Linné, the sub-dominants. 
Ling and bracken are apparently tenanted only by 
Hyalinia alliaria, Miller. 
Arion subfuscus, Draparnaud. 
Pyramidula rotundata, Miller, 
a trio always associated with sandstone heaths. With these 
species we find on Exmoor Arion intermedius, Norman, and 
Limax arborum, Bouchard-Chantereaux, the latter, however, 
occurring chiefly on the lower slopes in the vicinity of the oak 
woods. 
The fluviatile mollusca of the Upland Area must now be 
considered. 
D 
