Xhiii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



of the Devonian formation, as shown in North Devonshire, is identi- 

 cal with the lower beds of the Carboniferous formation in Western 

 England. The probability of this being the case was pointed out by 

 Sir H. DelaBeche in the * Report on Devonshire and Cornwall,' but 

 the subsequent working-out of the fossils by Professor Phillips and 

 Mr. Sowerby showed so many peculiar species identical with those 

 from strata below the Carboniferous limestone on the Continent, that 

 the beds in question (the Pilton group of Professor Phillips, — the 

 fifth group of Professor Sedgwick and Sir R. Murchison) have been 

 regarded as the upper portion of the Devonian rocks, with which, 

 however, they have very few fossils in common. A careful examina- 

 tion of the Lower Limestone Shale by Mr. Salter during the past 

 summer, in East and West Pembrokeshire, has led him to the con- 

 clusion that these beds, interposed as a shaly series between the 

 carboniferous limestone and the true old red sandstone, should be 

 considered as a part of the Carboniferous system, all the more abun- 

 dant fossils being characteristic of that formation. In East Pem- 

 brokeshire these beds repose on the Old Red Sandstone, which con- 

 tains but few fossils, and which in West Pembrokeshire loses its red 

 colour, and consists of yellow sandstones and limestones, with Avicula 

 Damnoniensis and CucullcEa trapezium overlaid by a pecuHar series 

 of shales and sandstones, with frequent fish- and coprolite-beds. 

 When Mr. Salter crossed the Bristol Channel and examined the 

 upper beds of the Devonian rocks, where the red colour has been 

 absent from a still larger portion of the upper Old Red, he found 

 that the yellow sandstones and associated limestone were identical 

 with those which he had seen in West Pembrokeshire. Here also 

 the beds containing Avicula Damnoniensis, CucullcEa, and a peculiar 

 trilobed Bellerophon were overlaid by a great shaly and slaty series 

 full of the same Carboniferous fossils {Spirifer, Terehratula, &c.), 

 with fish beds containing the same species, and made up of arenaceous 

 limestone and shales, which, but for their more complete slaty 

 cleavage, could not be distinguished from those of Pembrokeshire. 

 Mingled, however, with the mass of carboniferous fossils, Mr. Salter 

 found in abundance those pecuhar species Strophalosia caperata and 

 Phacops latifrons, which characterize this district, and are not 

 known in Pembrokeshire. The latter species, indeed, is a decidedly 

 Devonian type, rising up in this instance for a considerable thickness 

 (many hundred feet at least) into the lower carboniferous deposits. 

 Mr. Salter therefore considers that, as already suggested by Mr. 

 D. Sharpe, on fossil evidence alone, this group should be cut off 

 from the Devonian and included in the Carboniferous system. It is 

 the Carboniferous slate of Dr. Griffith, and occurs in great thickness 

 in Ireland, with a highly cleaved structure. 



It will be a subject of congratulation to those who take an interest 

 in the geology of Ireland, to learn that the Government has at length 

 determined on introducing the one-inch scale of maps for the use of 

 the Ordnance Geoloo:ical Survey of that country. 



The six -inch scale, however useful for a survey of landed property, 

 or for registering minute geological features, is far too unwieldy and 



