Rocks of North Devon, S^c. 123 



receive that system as an infallible guide when we step out of 

 the Silurian region, and pass into other tracts of transition or 

 protozoic origin. 



Again, " Mr. J. de C. Sowerby is of opinion that all the 

 fossils therein enumerated (p. 21.)* as belonging to the trans- 

 ition limestone of Cork are, with one exception, characteristic 

 fossils of the carboniferous limestone of England and Ireland, 

 and therefore that they are of the same geological age as those 

 which in another part of the memoir are described as ex- 

 cliisivelij belonging to the carboniferous strata." I must here 

 remark that, not exclusively would have been a more correct 

 expression, several of the species being there marked as com- 

 mon to transition countries also. 



" Judging from the printed lists. Prof. Phillips also thinks 

 that the Cork limestone fossils are carboniferous." And 

 " Mr. Sowerby agrees with me in believing that the only 

 fossils alluded to by Mr. Weaver, which really belong to the 

 more ancient rocks (Silurian, &c.), are those enumerated 

 (pp. 10. 15. et seq.)." 



Again, " From an inspection of Mr. Weaver's map alone, I 

 cannot avoid surmising that the localities where true Silurian 

 fossils might occur, are those alone where such have really 

 been detected, as the strata in those situations are separated 

 from the carboniferous limestone by large masses of Old Red 

 Sandstone. (See Smerwick Harbour, &c., on the coast of 

 Kerry, and the coast of Bonmahon River, Waterford.) The 

 Old Red Sandstone, that important feature of separation, being 

 wanting (on the south) in all the remainder of the country 

 described, is it hazarding too much to suggest, that some of 

 the limestones which there occur, and which are loaded with 

 carboniferous fossils, may be outliers and remnants of. the base 

 of that system, which we know to be so vastly expanded and 

 widely diffused throughout other parts of Ireland?" 



The reader being thus put in {)ossession of Mr. Murchison's 

 view of the case, I must now entreat his attention to my own. 

 I have to observe in ihefrst place that the number of fos- 

 sil species which I have enumerated as occurring in the Cork 

 great band of limestone, is forty-eight ,• of which ii'oentyfive 

 species are referable to the genera Spirifera, Terebratula, 

 and Producta. 



2ndly, Of the other fossils there are seven species which 

 have been found in the Cork limestone alone ; namely, 'Nau- 

 tilus funatus^ N.compressus; F,iioynphalus triangularis^ E, ovalis; 

 Ampullaria ovalis ; a species of Solarium ; Isocardia ohlonga. 



* Memoir on the South of Ireland in Geol. Trans., vol. v. Second Se- 

 ries. 



