ETHERIDGE DEVONIAN ROCKS AND FOSSILS. G81 



the three continental areas, where, as with us, the upward strati- 

 graphical succession into the overlying Carboniferous through the 

 Upper Devonian (when represented) is complete. It is the genera 

 of Brachiopoda [Uncites, Merista, Davidsonia, StnTigocephalus, Cal- 

 ceola, Pentavierus, &c.), the whole of the Coelenterata (51 species), 

 with all the Amorphozoa (9 species, which are unquestionably Lower 

 and Middle Devonian), the Cyrtoceratites (11 species, all Middle 

 Devonian), added to the rich numerical assemblage of species (vide 

 Tables II., Y., YII., YIII., IX.) which do not occur in the succeeding 

 Carboniferous, that establish a distinctness and give a reality to 

 this Middle Devonian group, which nothing but conclusive proof of 

 unconformity here or abroad can ever shake. 



I cannot doubt, therefore, that in North Devon the geological age 

 of the fossils is proved by the stratigraphical position of the beds 

 containing them, and that as there is no physical break in the up- 

 ward rock-succession from the Lynton and Ilfracombe group to 

 the Baggy series through the Pickwell-Dovni sandstone, neither is 

 there in the zoological continuity and persistency of species that 

 gradually lived on, or passed up, to the Upper Devonian, or Upper 

 Old Eed Series of Baggy and Marwood, and to the Croyde beds to the 

 south. 



Comparison, then, can easily be made between those species that 

 are common to the Middle and Upper Devonian and the Carboni- 

 ferous Slate &c. of the same area, believing as I do that the rocks 

 and assemblage of fossils south of Baggy, at Croyde, Braunton, and 

 Barnstaple &c., are the Carboniferous Slates and Coomhola Grits of 

 the south of Ireland, but that in the North-Devon area we have a 

 well-marked Upper-Devonian fauna below that (the Baggy, Marwood, 

 and Sloly series), which, if they did not precede the Irish forms in 

 time, were deposited in a different area. 



I maintain, therefore, that the peculiar Devonian genera and 

 species have a most definite value, because we know their stratigra- 

 phical place with relation, at least, to the Carboniferous group above ; 

 and although no one locality can perhaps be pointed out where fully 

 developed Upper Silurian rocks below, and fully developed Carboni- 

 ferous Limestone above, with the Devonian slates and limestone can 

 be seen in one section, it does not necessarily foUow that, because 

 we have not seen it in its comj)leteness or totality, we should deny 

 all experience, and reject the views of every competent observer, 

 when so much separate evidence exists. 



It may be asked what is the history of that great mass of so- 

 called Old Eed Sandstone in South Ireland? and why the uncon- 

 formity amongst the Scotch Old Eed Sandstones themselves ? what 

 caused that change from the marine Silurian to the barren or non- 

 fossiliferous Old Eed of the Silurian area ? 



The Table constructed by Professor Jukes at pp. 364-5 *' is anything 

 but the right way to put the question of recurrence ; it is sim])ly 

 comparing the Devonian species with each other in two different 

 areas — comparing forms that lived on through the whole group, from 

 the Lower portion to the Upper, which upon the law of continuity 

 * Notes for a oomparisow, &c., p. 578. 



