260 PROP. E. HULL ON THE GEOLOGICAL RELATIONS 



That the " Pilton " and " CiiculUa-'' or " Marwood " beds are the 

 equivalents of the " Coomhola grits and slates " of the South of 

 Ireland, and therefore (as shown above) of Lower Carboniferous 

 age, is evinced by a community of species to a large extent. Of these 

 the following have been kindly determined for me by Mr. Baily, 

 F.G.S., from the collections of the Irish Geological Survey : — 



Species common to the Pilton and Marivoocl beds of Devonshire, and 

 to the Coomhola beds of the South of Ireland. 



Brachiopoda : Chonetes hardrensis, JRhynchonella jpleurodon, 

 Streptorhynchus crenistria, Strophomena rhomboidalis, var. analoga, 

 Productus scabinculiis, Spirifer Urii, Lingula squamiformis. 



Conchifera : Cucullcea Hardingii, C. trajpezium, C. amygdalina, 

 Avicula damnoniensis. 



The great majority of the forms range up into the Carboniferous 

 Slate, and some into the Carboniferous Limestone, and clearly prove 

 the strong Carboniferous, rather than Devonian, affinities of the Pilton 

 and Marwood beds. 



yi. E-ELATIONS BETWEEN THE IeISH AND DEVONSHIRE SECTIONS. 



Having thus far described the general descending series of both 

 districts, it is necessary to pause at this point, because the analogy 

 between the two series here ceases altogether ; for, as I believe, 

 and as I hope to be able to demonstrate, the underlying Middle and 

 Lower Devonian series of Devonshire is entirely unrepresented in 

 the Irish area, nor do we again begin to correlate the beds till we 

 arrive at the basement formation of all, namely, " The Foreland 

 Beds." 



With regard, however, to the series above described, there is a re- 

 markable concurrence of opinion between the most eminent geologists 

 who have made the comparison, that all the beds from the base of 

 the Carboniferous Limestone down to the top of the Pickwell-Down 

 Sandstone are representatives of the Lower Carboniferous Slate and 

 Coomhola grit of the South of Ireland. 



This view was clearly put forward by the Eev. Dr. Haughton, 

 F.K.S., as far back as 1855, in a paper read before the Geological 

 Society of Dublin*, and was laid down and defended, both on strati- 

 graphical and palaeontological grounds, by the late Mr. Salter in the 

 year 1863t. Mr. Salter shows that, while the Carboniferous Slate 

 and Barnstaple beds are characterized essentially by Carboniferous 

 forms, the Pilton and Marwood beds (Oucullcea-zone) contain some 

 Upper Devonian forms, many of which are found in the Coomhola- 

 grit series of the Co. Cork. 



The correlation thus established by Haughton and Salter is, in 

 the main, the same as that subsequently adopted by Jukes t and 



* " On the Evidence afforded by Fossil Plants as to the boundary line between 

 the Devonian and Carboniferous Kocks," Journ. Geol. Soc. Dubl. vol. vi. p. 227. 



t "On the Upper Old Eed Sandstone and Upper Devonian Eocks," Quart. 

 Journ. Geol. Soc. vol. xix. pp. 488 &c. 



I Supra cit. p. 345 et seq. 



