of the Older Stratified Hocks of Devonshire mid Corimall. 249 



we consider as fixed,) into the Devonian equivalents of the 

 old red sandstone. 



Under this view, the supposed difficulty arising out of the 

 existence of certain species of fossil plants, both in the carbo- 

 niferous system and "undisputed greywacke rocks*," is at 

 once obviated : for the hard brown and greenish-grey micaceous 

 sandstones between Ilfracombe and Barnstaple, in which these 

 plants were discovered f, are now placed in the upper part of 

 the old red sandstone, in which all true analogy would impel 

 us to look for the presence of some of the species of plants 

 common to the carboniferous epoch : and we are strengthened 

 in this conviction by the evidence of the shells on the same 

 line with these plants, among which is a species, as before 

 stated, of Bellerop/ion, identical, as far as casts can prove it, 

 with a shell figured from the old red sandstone. In regard 

 to the organic remains of the old red sandstone, one of the 

 authors has indeed already published those forms which mark 

 its passage into the Silurian system. Aware of the enormous 

 thickness of this arenaceous series in the British Isles, and 

 having ascertained, to a certain extent, the peculiarity of its 

 fossils, particularly of its fishes, he proposed that it should be 

 considered " a system" intermediate between the Carbonife- 

 rous and Silurian systems J. 



Whilst, however, he indicated the existence of certain 

 shells connecting the old red and Silurian systems, as well as 

 fossil fishes of very peculiar types in the former, he knew too 

 well that the greater mass of this vast system, particularly all 

 its upper members, contained no organic remains in the coun- 

 tries which he illustrated. In stating that "the strata (Carbo- 

 niferous and Silurian), so broadly distinguished by their or- 

 ganic remains, are separated by accumulations of enormous 

 thickness, and that the vast time occupied in their deposit ac- 

 counts satisfactorily for an almost entire change in the forms 

 of animal life ;" he also thus declared his anticipation con- 

 cerning the old red system : " We are yet unprovided with 

 zoological links to connect the xdmle series, though I have no 

 doubt that such proofs will be hereafter discovered, and that 

 we shall then see in them as perfect evidences of a transition 

 between the old red and carboniferous rocks, as we now trace 

 from the Cambrian, through the Silurian into the old red sy- 

 stem §." 



* See De la Beclie's Report, |). KiS, et seq. 



t The plants were first observed by Major Ilartiing and the Rev. D. 

 Williams. 



J See Silurian System and Map. 



4 Miirchison's Silurian System, p. 58.'*. 



