Proceedings of the British Association. 351 
this series are very few organic remains. It is several feet in thick- 
ness, occupying the whole coast from the west end of the Valley of 
Rocks to Combe Martin.—3. The calcareous slates of Combe Mar- 
tin and I}fracombe, of very great aggregate thickness, abounding in 
organic remains, and containing in a part of their range at least nine 
distinct ribs of limestone burnt for use. This limestone is prolonged 
into Somersetshire, and appears to be the equivalent of that on the 
flanks of the Quantock Hills.—4. A formation of greenish and lead- 
colored roofing slate of great thickness, and occupying a well defined 
zone in North Devon, its upper bed alternating with and gradually 
passing into a great deposit of sandstones of various colors and mica- 
ceous flagstones. These siliceous masses alternate with incoherent 
slates, and are in some places surmounted by great masses of red unc- 
tuous shale, which, when ina more solid form, generally exhibit cleav- 
age oblique to the stratification.—5. The Silurian system resting 
conformably on the preceding, and of great thickness, on the north- 
western Coast, containing many subordinate beds and masses of lime- 
stone. In its range towards the eastern part of the county, it grad- 
ually thins off, but its characters are well preserved, and it every 
where contains vast numbers of characteristic organic remains.— 
6. The carbonaceous system of Devonshire, in a direction east and 
west across the county, in its southern boundary so close to Dartmoor 
that its lower beds have been tilted up and altered by the granite. 
It occupies a trough, the:northern border of which rests, partly in a 
conformable position upon the Silurian system, and partly upon older 
rocks, probably of the division No. 4. Its southern border also rests 
on the slate rocks of Launceston. It every where exhibits a suc- 
cession of violent contortions. In some places it is overlaid by 
patches of green sand, and west of Bideford by conglomerates of 
the new red sandstone. The lowest portion of this vast deposit is 
generally thin bedded, sometimes composed of sandstone and shale, 
with impressions of plants, sometimes of indurated compact slate, 
containing wavellite. ‘These beds are surmounted by alternations of 
shale and dark colored limestone with a few fossils. Subordinate to 
these, there are on the western side of the county thin veins and 
flakes of culm or anthracite ; but this is wanting on the eastern side, 
and the calcareous beds are more expanded. The higher beds of 
this deposit are well exhibited on the coast west of Bideford. These 
often contain impressions of vegetables. Though ina state of greater 
induration than the ordinary coal measures of England, and even in 
