INTRODUCTION. XXXIil 
stones. The recent deposits are very scanty, consisting chiefly 
of alluvium on the margins of rivers and streams. The soils 
of this area do not shew such a marked diversity of vegetation 
as one might expect. They differ, however, in one particular, 
a very important one in connection with this paper, in the 
presence of large woods of oak, ash, and oak-hazel. Ash 
woods occur chiefly en the limestones, oak on the sandstones, 
and oak-hazel on the deep marls and clays. There are no such 
woods on the Levels, only plantations of recent origin. 
A. THE DEEP MARES AND CLAYs. 
The deep marls and clays consist of large tracts of New 
Red (Keuper) Marl at the foot of the Carboniferous Lime- 
stone hills, about Taunton and Wellington, and the uplands 
bordering the Bridgwater Levels; of Lias, the northern slopes 
of the Polden Hills are Lower Lias, the Middle and Upper 
Lias occupy the country about Ditcheat, West Pennard, 
Butleigh, and Street. The Bradford Clay, Fuller’s Earth, 
and Oxford Clay are exposed in the eastern uplands. 
There are extensive oak-hazel woods in the Butleigh and 
Copleigh districts. On the margins of these woods we find in 
association with Primula vulgaris, Huds; Spirea ulmaria, 
Linné; Ranunculus ficaria, Linné, and other hedgerow plants : 
Hygromia rufescens, Pennant (dominant). 
Agriolimax agrestis, Linné. 
Arion ater, Férussac. 
Vitrea nitidula, Draparnaud. 
Helix nemoralis, Linné. 
Cochlicopa lubrica, Miiller. 
In the deeper parts of the woods we find, under sticks 
amongst such plants as Mercurialis perennis, Linné; Nepcta 
hederacea, Trev.; and Euphorbia amygdaloides, Linné : 
Limax maximus, Linné, associated with 
Vitrina pellucida, Miiller. 
