INTRODUCTION. xl 
Bristol Avon, forming the dividing line from Gloucestershire. 
Its tributaries, the Frome and Chew, carry off the waters 
from the north-east side of the Mendips. The river Yeo 
takes the drainage of the north-western slopes of the Mendips, 
and enters the channel a few miles below Clevedon. The 
Axe conducts the waters from the southern slopes of the same 
range to the sea below Weston-super-Mare. The Polden 
Hills are drained on the north by the Brue, which also carries 
off the waters of the eastern uplands about Bruton and Castle 
Cary, in the neighbourhood of which towns enormous numbers 
of shells may be found in the rejectmenta left on the banks 
after heavy floods. Mr. John Morland, in a recent letter to 
me, comments upon the large numbers of shells occurring in 
the “drift” left by this river near Glastonbury. “I think I 
obtained 60 or more species from this source, including a single 
specimen of Aeme fusca.” The southern slopes of the Poldens 
are drained by the Cary, a tributary of the Parrett, which it 
enters near Dunball station, below Bridgwater, in an artificial 
channel under the name of King Sedgemoor Drain or Cut. 
Another tributary of the Parrett, the Yeo (formerly Ivel), 
enters Somerset near Yeovil, and passing through IIchester, 
joins the parent stream at Langport. From Langport the 
Parrett meanders across the county to the sea, and forms, 
with the tributary Yeo, the dividing line between the two 
vice-counties, North and South. The Devonshire Axe and 
the Exe, which drain respectively the southern slopes of the 
Blackdown Hills and Exmoor, flow southward into Devon- 
shire. 
The wild stretches of Exmoor comprise some of the highest 
land in the county, attaining 1,707ft. at Dunkery Beacon. 
The Quantock hills stretch from a few miles to the north-west 
of Taunton towards the sea in the direction of Watchet, but 
do not reach the coast; Wills Neck, the highest point, is 
1,262ft. The Mendips stretch from the neighbourhood of 
Wells to Weston-super-Mare, and are the most extensive hills 
