568 



PROCEEDINGS 0^ THE aEOLOGICAL 8O0IETY. 



Plate XVII. 



{T%e species figured in this plate have all been obtained from Rohvell.) 



Fig. 1. Trochus Holwellensis, s^ec. noY.: back view. 



2. : base, enlarged. 



3. Neritopsis Icevis, Stol. : front view. 

 4. : top view, 



5. Trochus gradatus, spec. nov. : enlarged. 



6. Phasianella turbinata, Stol. : back view. 



7. Amberleya alpina, Stol. : front view. 



8. Delphinula reflexilabrum, Home : front view. 

 9. : top view. 



10. nuda, spec. nov. : back view. 



11. Trochus latilabrus'^ , Stol.: back view. 



12. Nerincea Horneri, spec. nov. : front view. 



13. Pleurotomaria Buchi, Desl. : front view. 

 14. : surface view. 



15. Solarium lunatum, spec. nov. : top view. 



16. Turbo nodulo-carinatus, spec. nov. : back view. 

 17. : front view. 



18. solidus, spec. nov. : front view. 



19. Avicula nuda, spec. nov. 



20. Opis triangularis, spec. nov. : dorsal surface. 



21. Lima Ifeslongchampsi, Stol. 



22. scrobiculaia, Stol. 



23. densicostata, Quenst. 



25*. Tecten Bollei, Stol. 



26, mrticillus, Stol. 



27. palosus, Stol. 



2. On the Physical Stkuctfee of West Someeset and I^oeth Devoit, 

 and on the Pal^oisttological Value of the DEVojsriAisr Possils. By 

 Robeet Etheeidge, Esq., P.G.S., F.R.S.E., Palseontologist to the 

 Geological Survey of Great Britain. 



Contents. 



I. Introduction. 

 II. History and Literature. 

 III. Structure and Succession of the 

 Eocks of West Somerset. 



1. Cannington Park Limestone. 



2. The Quantock Hills. 



3. Dunster, Minehead, and Port- 

 lock Areas. 



4. Dunster to Dulverton. 



5. Valley of the Barle and west 

 of Dulverton. 



6. South of Dulverton. 



7. Dulverton to Wivehscombe. 



8. Dunster to Brendon Hills and 

 Nettlecombe. 



Withycombe by Dunster. 

 Goldsoncot. 



Higher Roadwater, Trap Hole, 

 Lod Huish. 



10. 

 11. 



IV. Structure and Succession of the 

 Rocks of North Devon. 



A. Lower Devonian Group. 



1. Porlock to Lynton. 



2. Foreland, east of the River 

 Lynn. 



3. Woodabay and Heddon's 

 Mouth. 



4. Conclusions relative to the 

 Lower Devonian Series of 

 West Somerset and the Lynton 

 area. 



B. Middle Devonian Grroup. 



1. Heddon's Mouth to Barn- 

 staple. 



2 Ilfracombe to Baggy Point 

 .via Morte Bay, Little Hang- 

 man Hill, and West Challa- 

 combe to Ilfracombe. 



