686 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. 



SO remarkably broken and incomplete as the Old Eed and Devonian 

 series, illustrating lapses of unrepresented time, which are proved 

 either by the great and complete change in, or total absence of, life- 

 remains. 



I have endeavoured, however, to show that it is possible to 

 parallel the division of the Old E-ed proper with its chronological 

 equivalents, the marine Devonian series, which were deposited in a 

 different, although contiguous, geographical area. 



I contend therefore that the Devonian system, as a group of 

 strata, both physically and palseontologically, may be (as long ago pro- 

 posed) naturally and conveniently divided into a Lower, a Middle, 

 and an Upper series, and that there is valid reason for believing that 

 this system equalled in time the whole of the deposits of the Old Eed 

 Sandstone proper ; but we have no real means of establishing arbi- 

 trary lines of agreement, or of strictly correlating the received divi- 

 sion of the one to that of the other, for the want of clear palseonto- 

 logical agreement and evidence ; all that can be said is, that, in the 

 sequence of rock-masses, the Old Eed Sandstone and marine Devo- 

 nian, be they absolutely equivalent or contemporaneous or not, 

 occupy a place above the Silurian on the one hand and below the 

 Carboniferous on the other. The evidence of succession is clear in 

 Wales, Hereford, and Shropshire as regards the Old Eed Sand- 

 stone ; in the Devon area, on the other hand, it must be assumed, 

 as we have no visible base-line uniting the Lower Devonian with 

 the Silurian, though, for aught we know to the contrary, they may 

 overlie Silurian rocks in the Lynton area, in North Devon ; but the 

 testimony of palaeontological research has established beyond any 

 doubt that in Devonshire and Western Europe there exist three 

 natural groups, which stratigraphically and zoologically succeed 

 each other, viz. : — a Lower or Lynton, equalling in time and position 

 the Lower Old Eed Sandstone of the Silurian area ; a Middle series, 

 the Ilfracombe beds of North Devon and their equivalents (the New- 

 ton Bushel and Torquay slates and limestones) in South Devon, 

 which probably equal the Middle Old Eed Sandstone of Hereford- 

 shire, Gloucestershire, and Glamorganshire ; and a true Upper Devo- 

 nian series, resting in North Devon upon the Morte-Bay Upper Old 

 Eed Sandstones (of Pickwell Down, Dulverton and Wiveliscombe), 

 which also is equivalent to the Upper Old Eed of the Pembroke area 

 in South Wales ; and it is upon these Pickwell-Down red sandstones 

 that the slates, grits, and arenaceous flaggy beds of Baggy, Marwood, 

 Sloly, and Croyde conformably rest, which contain the marked assem- 

 blage of Upper-Devonian forms. They are three distinctly marked 

 physical and palaeontological groups, true as to rock-succession, and 

 equally well characterized by organic remains, especially the Middle 

 or Ilfracombe group, with its Coelenterate and MoUusca fauna : that 

 this order of succession exists is incontestably proved by the clear 

 interpolation of the middle fossiliferous slates and limestones, and 

 the extensively developed series of unfossiliferous slates of Lee, 

 Eockham Bay, Mortehoe, and Woolacombe, and it is also strength- 

 ened by the non-faulted range of Pickwell Down. No fault or 



