690 PROCEEDINGS OE THE GEOLOGICAL SOCIETY. 



lieve, successfully), that thousands of feet of fossiliferous slates and 

 limestones occur, in regular sequence through all North Devon from 

 north to south, or from the Poreland to Barnstaple. Had Professor 

 Jukes stated that upon the uppermost beds of the Upper Old Eed 

 Sandstone at Pickwell Down rested those containing the Upper-De- 

 vonian marine fossils, or in part the equivalent of his Carboni- 

 ferous slate and Coomhola grits, he would have read the real struc- 

 ture of the country ; now we are asked to believe, through the 

 agency of an unknown and supposititious fault with a northern down- 

 throw, or an anticlinal running east and west from Morte Bay to 

 Wiveliscombe, that these Upper Devonian beds (his Carboniferous 

 slates) are repeated in the Lynton area, being rolled, undulated, 

 or faulted to the north. 



Upon this hypothesis, therefore, there is no such group as Devo- 

 nian in North Devon, the whole Lower and Middle series with 

 their characteristic fossils and clearly defined stratigraphical place 

 being swept away, and substituted by the Carboniferous Slate, but 

 only through similarity of aspect, and not identity, as based either 

 upon physical or paleeontological grounds. On the other hand, there 

 may be grounds for endeavouring to establish contemporaneity 

 between the Upper Devonian series of North Devon and the Car- 

 boniferous Slates of the south of Ireland upon the principle of 

 geographical rather than chronological distinction ; and the aspect of 

 the beds both in North Devon and Ireland, and their zoological 

 relations one to the other through certain classes, especially the 

 Brachiopoda (vide Tables IX. and X.), is clear, and to be expected 

 when we know that the Devonian preceded the Carboniferous in time. 

 And it is admitted that the Petherwin, Baggy, Marwood, Sloly and 

 Croyde beds are older than the Carboniferous Slates, and not clearly 

 represented in the south of Ireland (vide Tables IX. and X., and 

 Professor Jukes's " Notes for a comparison " &c. &c., pp. 17, 22, 27). 

 I am disposed, therefore, from careful examination of the Upper De- 

 vonian fauna in North Cornwall and North Devon, and of that of 

 the Boulonnais and Belgium, to collate the species in the Irish Car- 

 boniferous slate and Coomhola series with the English types rather 

 than adapt the latter to the Irish. 



There are in the Upper Devonian rocks of North Devon south of 

 Pickwell Down, including Petherwin, 136 species*, representing 57 

 genera: 30 of these 136 species, in this area, may be Carboniferous, 

 assuming that the Barnstaple beds are of that age ; but no more 

 than 40 are known to pass up to the Carboniferous Slate and Car- 

 boniferous Limestone in any area : the remaining 96 are exclusively 

 Upper-Devonian species that lived earlier in time than the Carboni- 

 ferous f, and underlie the Coomhola Grits and Carboniferous Slate, so 



* Omitting the Petherwin, there are 110 true North-Devon forms; the addi- 

 tional Petherwin species occur only in that area amongst Carboniferous-slate 

 and Carboniferous-limestone species. 



t Professor Jukes gives a list of 84 species at pp. 22-27, but places them in 

 the Carboniferous Slate on the assumption only that they are so ; a Eoman 

 letter indicates (as stated at p. 17) the Old-Eed-Sandstone localities, hxit not yet 

 Carboniferous-slate localities. My Table IX. and that list will correct each other. 



