ETHERIDGE — DEVONIAN ROCKS AND FOSSILS. 605 



red grits, are the large and ^Yell-known Myalince and Naticce, 

 occurring as casts only ; their position, however, at the Little Hang- 

 man and at Holstone in the same grits, fixes their place. At Sprc- 

 combe, near Oareford, Wishet, and the Eed Deer, near Black Barrow 

 Down, in the North Forest, the same shells, with casts of Favosites 

 cervicornis, Cucullcea, Sanguinolaria, Solen ?, Macrocheilus hrev'is, 

 Pleurotomaria, and Loxonema, occur*. At Combe Martin, on crossing 

 the river to the south, a marked change in the aspect of the country 

 takes ]jlace ; a ridge of elevated country richly wooded, stretching 

 from AVidmouth Head on the west to Kentisbury on the east, marks 

 the outcrop of the Limestone series ; but unlike the beds of the same 

 age in South Devon, they are here intimately interstratified with 

 the slates in irregular alternating thick- and thin-bedded lenticular 

 calcareous masses, yet very continuous. Li the first or lowest 

 series, south-east of the village, the united thickness of the lime- 

 stone beds is from 60 to lOQ feet, and they are extensively burnt for 

 lime. These calcareous beds are chiefly composed of the Avell-marked 

 Devonian corals, CyatJio])liyllum ccBspitosuni, C. Uallii, Favosites cer- 

 vicornis, Stromatopora concentrica, and Heliolites porosus, with Tri- 

 merocejjJialus Icevis (casts) and Atrypa reticularis ; many of these 

 species are distributed through all the quarries, though sparingly. 

 There appear to be two well-defined series of limestones, confined to 

 about 1000 feet of vertical strata, and occupying the middle part of 

 the lower division of the Ilfracombe group ; it is these limestones that 

 here, as in South Devon, so eminently characterize the Middle De- 

 vonian Rocks, and, as on the continent, contain that peculiar 

 group of corals, totally unhke, and diff'erent from, those of the under- 

 lying Silurian rocks as well as, luithout exception, the succeeding 

 Carboniferous ; for of the fifty species of corals known in the 

 Middle Devonian series of North and South Devon and Corn- 

 wall, one doubtful species only is said to occur in the Silurian rocks, 

 viz. Favosites fibrosa, and only one is said to pass up into the Car- 

 boniferous series, viz. Amplexus tortuosus, of which, however, we have 

 no authentic evidence. In the North Devon area, thirteen species 

 occur, and with one exception are confined to it — one species only 

 recurring in the beds south of Baggy, viz. Petraia pleuriradiaUs ? ; and 

 yet, on comparison with the Eifel and Belgian Devonian strata, 20 

 species, or 40 per cent., are common to the Middle Devonian series 

 of Devonshire and Europe. A similar relation and difference I hope 

 to show in all the groups of organic remains that occur in this for- 

 mation in Great Britain. 



Crossing the calcareous group of slates from the Lee Quarries, 

 east of Combe Martin, to the high ground of Berrydown, we again 

 (near the cross roads) meet with the finer-grained, non-calcareous, 

 unfossiliferous Mortehoe slates, which here occupy an elevated 



* No one has more carefully studied the Ilfracombe group of rocks than 

 R. Valpy. Esq. ; and to him am I indebted for considerable information rela- 

 tive to fossil localities, permission to examine his rich Collection, and also 

 his notes upon tliis part of the North Devon coast. He has himself c^Ualogucd 

 and noted upwards of 50 species from the Ilfracombe group alone, a work of con- 

 siderable time and labour. 



