ETHEBIDGE DEVONIAN ROCKS AND FOSSILS. 



593 



Fig. 5. — Section from Claylianger over Main Down to Whitfield. 



Langlev Marsh. 

 (Washbattle 

 Clayhanger. Chipstable. Main Down. Rhaddon. Mills.) Whitfield. 



Upper Devonian. 



Upper slates of Middle Devonian. 



8. Danster to the Brendon Hills and Nettlecomhe. — This route was 

 selected for an examination of the Devonian beds in ascending order, 

 especially those members of the Middle group that mantle and 

 sweep round the southern and eastern flanks of Croydon Hill, 

 where two, if not three, distinct series of succeeding limestone bands 

 are well exposed. It is, indeed, a precise repetition of the con- 

 ditions observable at Combe Martin and Ilfracombe on the west. 

 Not only is the succession clear, but the relations of the slates to 

 theii' accompanying coral-limestones can be well examined. A line 

 drawn from Dunster Park, north of Langcombe, Lod Huish, and 

 Croydon, and round to Treborough "Wood, Drucombe, and Clicket, 

 to Ashwell, before mentioned, will describe approximately the 

 boundary between the red gritty sandstone series of Croydon (the 

 Hangman and Trentishoe grits) and the succeeding slates and lime- 

 stones of the Middle Devonian or Hfracombe group, which con- 

 formably rest upon these upper red beds of the Hangman grits. 

 All the band of country east and south of this line to the base of, 

 or junction with, the great sandstone band described as striking 

 from Morte Bay to Wiveliscombe is occupied by the Ilfracombe 

 slates and limestones, and its higher member the grey, smooth, 

 non-fossQiferous slates of Lee, Rockham, and Mortehoe. It is the 

 lower calcareous and fossiliferous division, however, which we have 

 chiefly to deal with. 



9. Withy comhe hy Dunster. — We have here the first exposure of n. 

 continuous band of limestone rich in corals, which can be traced 

 round the Croydon promontory, to Treborough, the species occurring 

 here being the same as those in the limestones at Newton Bushel, 

 Torquay, and Plymouth in South Devon. From these limestones 

 at HiU Farm have been obtained no less than fourteen species of 

 Corals and Polyzoa, as well as Brachiopoda ; and the same forms 

 are distributed generally through these AVest Somerset Middle 

 Devonian beds. The following are those that have been found by 

 Spencer G. Perceval, Esq., of Severn House, Henbury, near Bristol: 

 — Ccelenterata : Favosites cervicornis, Blainv. ; Favosites reticulata, 

 Blainv. ; Alveolites suborbicularis, Lam. ; Cyathophylliim Damno- 

 niense, Lonsd. ; C. ccespitosum, Goldf. ; C. Bolloniense, Blainv. ; Cys- 

 tiphyllum vesiculosum, Goldf. ; Heliophyllum Halli, M. Edw. ; En- 

 dophyllum abditum, M. Edw. ; Ample.vus tortuosus, Phill. ; and 

 Syringophyllum. Polyzoa : Fenestella antiqua, Goldf. Amorphozoa : 

 Stromatopora concentrica, Goldf. Six of the species here enumerated 

 are abundantly distributed, and arc all typical of beds of the same 



VOL. XXIII. PART I. 2 s 



