146 Epwarp Hurt—The Relations of the Carboniferous, Devonian, and Upper 
derived. The thickness of these beds is very considerable ; but, owing to the 
occurrence of one or more flexures, 1t cannot be determined with accuracy. We 
may assume it to be somewhere about 1,000 feet. Mr. Champernowne, F.c.s., has 
shown that this division is fully represented in South Devon, near Totnes. 
(f.) Morthoe and Ilfracombe Beds.—The base of the Pickwell Down Sandstone 
is distinctly visible in a quarry by the side of the railway, south of Morthoe Station. 
The beds which underlie this formation consist of pale, grey micaceous slates, the 
materials of which might have been derived from the disintegration and denudation 
of gneissose or schistose rocks. These beds are unfossiliferous, and are followed 
in descending order by the Ilfracombe shales, slates, and limestones forming the 
important fossiliferous beds of the Middle Devonian group. These beds are laid 
open, not only in the fine coast sections at Ilfracombe, but also at Combe Martin, 
Watermouth, Widmouth, and Hagginton. According to Mr. Etheridge, this group 
has yielded 73 known forms, of which 35 (or 46 per cent.) are known in the corres- 
ponding beds of the Rhine, Belgium, or France; and only 8 species are known to 
pass upwards into the Carboniferous rocks of any area, viz. :—1! Gasteropod 
(Acroculia vetusta), 1 Polyzoon (Fenestella antiqua), 5 Brachiopods, and 1 
Cephalopod (Orthoceras cylindraceum).* 
(g.) Hangman Grits.—From beneath the Ilfracombe beds the great arenaceous 
formation called “The Hangman Grits,” or “ Martinhoe Group,” (T. Hall) are seen 
to emerge in the cliffs of Combe Martin Bay, which are succeeded in turn by the 
Lynton slates and earthy limestones forming, with the underlying Foreland grits, 
the Lower Devonian and passage beds into the Upper Silurian Series. 
(h.) The Lynton beds being fossiliferous are of special interest, and are strikingly 
laid open in the Valley of Rocks, where they form castellated tors and sharp crags 
which have been broken off along the faces of two intersecting systems of joint- 
planes. About 40 species of marine forms have been obtained from these beds, of 
which only 3 are known to pass up into the Carboniferous, viz. :—Cyathocrinus 
pinnatus, Fenestella antiqua, and Chonetes sordida ; while out of 1,154 species known 
in the British Silurian, only one (Atrypa reticularis) is considered by Mr. Etheridge 
to occur in the Lower Devonian, beds. Such are the paleontological relations of 
the Devonian group of rocks to those which both precede and follow it. 
(.) Foreland Grits—Lying at the base of the whole Devonian Series of North 
Devon occurs a remarkable group of rocks, because more antiquated in appearance 
than any of the grits or sandstones above described, and also because they bear a 
strong resemblance to the Glengariff Grits of the south of Ireland. These rocks 
are laid open to view in the cliff sections east of Lynmouth, and at Minehead. 
Their base is unseen, because (as has been shown by Sir H. De la Beche, and more 
The Rey. Dr. Haughton states that whitish sandstones, resembling the Kiltorcan beds, are well 
shown in a quarry at Oakhampton, on the southern outcrop of the beds. 
* Quart. Journ. Geol. Soc., Vol. XXIIL., p. 639. No less than 235 species are enumerated by Mr. 
Etheridge as occurring in the Middle Devonian beds of South Down. /bid., p. 651. 
