370 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 7, 



Where the Old Red Sandstone is absent, the Devonian beds may 

 perhaps repose conformably on the Upper Silurian, or unconformably 

 either on that or some lower formation. 



ly. Appendix. 



My colleague, Mr. E. Etheridge, has at my request drawn up a 

 complete catalogue of all the British fossils of the Devonian and 

 Old Hed Sandstone formations, so far as they are at present known, 

 with all the recent improvements in their nomenclature introduced 

 by Mr. Davidson and others. He has also shown their distribu- 

 tion, in parallel columns, in the several districts of Cornwall, South 

 Devon, and North Devon, subdividing the beds which occur in 

 those districts into the ordinarily received groups. He has also 

 subdivided the Old Eed Sandstone into Upper, Middle, and Lower, 

 according to the prevailing ideas as to the grouping of those beds. 

 He has added columns for Ireland, one showing the fossils which 

 occur only in the Coomhola Grits, the other, including these, in a 

 list which shows the whole fossils hitherto recorded from any part 

 of the Carboniferous Slate of Ireland. He has then shown, in 

 farther columns, the species which also occur in the Carboniferous 

 formations in other parts of the British Islands, taking the com- 

 monly received subdivisions of that formation ; and, lastly, has 

 given columns which mark the occurrence of any of the species 

 enumerated in the Ehenish Provinces, in Belgium, and in Prance. 

 Mr. Etheridge, in drawing up this list, has carefully confined him- 

 self to the recording of facts from the best authorities, irrespectively 

 of all hypotheses as to the classification of the beds. 



He then gives a Table, in which the numbers of species are com- 

 bined under their respective biological headings. From this it ap- 

 pears that the whole number of species is 529, of which, however, 

 112 are fish that occur only in the Old Eed Sandstone. If we omit 

 these from the total, as not affording any element of comparison, and 

 also omit the 12 species of plants, in order to confine the com- 

 parison to undoubtedly marine organisms, we have a total of 405 of 

 such organisms. Of these one only (Serpula advena) has been 

 found in the Old Eed Sandstone. If we omit this, and also the 

 freshwater Anodon of the Old Eed Sandstone, it leaves 403, or in 

 round numbers, 400 species of marine organisms found in the ma- 

 rine Devonian beds for comparison with fossils of the same class in 

 other formations. Of these 400 species, 13 only, chiefly Corals, are 

 said to occur in any Silurian rocks, while 92, or nearly a quarter of 

 the whole, occur in the undoubted Carboniferous rocks of other 

 parts of the British Islands. 



It also appears from the Table that the palseontological differences 

 between different areas of the Devonian beds are at least as great, if 

 not greater, than those observable between the Devonian and the 

 Carboniferous Limestone series. 



It is also to be recollected that the amount of difference apparent 

 on the comparison of lists of species, is to a certain extent delusive. 



