1866.] JUKES OLD EED SANDSTONE AND DEVONIAN. 369 



different species in beds which are so — and this sometimes within 

 very narrow geographical limits. 



13. General conclusion. — I would, then, beg leave to suggest, in the 

 first place, that the identification of the Old Eed Sandstone proper 

 with the Devonian beds was an over-hasty conclusion, and that, 

 till the question be finally settled, it would be well to discontinue 

 the use of the term Devonian for all beds which are, or are sup- 

 posed to be, really Old Eed Sandstone. One source of confusion 

 would thus be avoided. The term '' Devonian" would then be 

 confined to beds containing those species and genera of Brachiopoda 

 and other marine fossils which are commonly understood when we 

 speak of Devonian fossils. The Old Eed Sandstone certainly does 

 not contain any of these fossils. The plants and the Anodonta 

 which it does contain seem to point to a freshwater origin for it, 

 or at all events the neighbourhood of land. 



The Devonian beds, when the Old Eed Sandstone is detached 

 from them, will still be sufficiently extensive and important. The 

 peculiar genera and species belonging to them seem to have a very 

 wide range over the world in general, quite as wide perhaps as the 

 genera and species peculiar to the Carboniferous Limestone. 



I believe, however, that it will ultimately be found that the 

 genera and species which have the widest range of all, are those 

 which are common to the Devonian beds and the Carboniferous 

 Limestone. 



It may doubtless be thought a bold, not to say audacious, spe- 

 culation, but it occurs to me to ask whether we ought not rather 

 to look upon the Devonian beds as the most general type of those 

 which intervene between the Coal-measures and the Old Eed Sand- 

 stone, and regard the Carboniferous Limestone of the British Islands 

 and Belgium as a local and exceptional peculiarity. It seems to 

 me that good reasons might be urged for such a classification. 

 It would be represented in a condensed form in the subjoined 

 diagram. 



Fig. 18. 



Lower Coal-measures, with Fosidonovijja, AviculG])ecfen, Lunulacardium, 

 Goniatites, Orthoceras, Coelacanthoid Fish, &c. 



Carboniferous 

 Limestone. 



Devonian beds, or Carboniferous slate with Cypridinenschiefer, Strin- 

 gocephalus-, and Calceola-limestones, Spiriferensandstein, Marwoodand 

 Coomhola sandstones, &c. &c. 



Old Eed Sandstone, with Adiantites or Cychpteris and other Ferns, Knorria, 

 bagenarta, Cyclostigma and other plants, Anodonta, and fish of the genera 

 Coccosteus, Glyptolmaus, PhaneropUuron, Glyptopomus, «fcc. &c. &c. 



