46 REPORT-—1843. 
by red sandstone passing into conglomerate, alternating with red and occasionally 
reddish-gray shale, and higher in the series we meet thin beds of compact red lime- 
stone; next fine-grained red and bright yellow calcareous sandstone, containing some 
beds of bright yellow, fossiliferous dolomite, containing casts of Cucullea complanata, 
C. unilateralis, C. Hardingii, C. trapezium, Pullastra antiqua, with Nucula, Cypri- 
cardia, and some obscure univalves. These fossils are similar to those of Marwood 
in North Devon. 
The yellow beds appear to be succeeded by dark gray shale, the thickness of which 
cannot be ascertained, as it extends seaward under low water. This shale contains 
in abundance the scales of Holoptychius Portlockii, two or three varieties of Paleo- 
niscus, with bones, spines, &c. of fishes undetermined, together with fifteen varieties 
of Cythere, Modiola Macadami, Cypricardia socialis, Orthoceras regulare, and other 
_ fossil shells which are common in the gray shales, accompanying the arenaceous 
limestone in the West of Ireland. 
The southern portion of the section commences at Castle Espie on the shore of 
Strangford Lough. Resting unconformably on a greywacke base, we have here the 
lowest limestone of the carboniferous series: it contains Actinoceras Simmsii, which 
is probably the same as Orthoceras giganteum of Sowerby, Actinoceras pyramidatus, 
Producta gigantea, P. latissima, Orthis cylindrica, Spirifera imbricata, Athyris glabri- 
stria, Syphonophyllia cylindrica, Turbinolia fungites, &c. ; these strata are covered by 
beds of red sandstone, dipping at a small angle under an arm of Strangford Lough, 
but succeeded on Scrabo Hill by reddish-gray and light yellowish-gray fine-grained 
sandstone. The sandstone of the Scrabo quarries is much used for building in the 
surrounding country. At Scrabo, and to the north and east of it, the rock has the 
same dip and inclination as at Castle Espie, accumulating to the north till it comes 
in contact with the greywacke slate of the Ards peninsula, By surveying other 
points in the range of this rock, Mr. Griffith arrives at the conclusion that the sand- 
stone of Scrabo Hill is above the limestone of Castle Espie, and also that the sand- 
stones and gray shales of Cultra are higher in the series than the same limestone. 
Castle Espie limestone appeared to represent the impure arenaceous limestone of the 
north coast of Mayo, and of Pettigoe in Fermanagh, and the gray shales which contain 
the ichthyolites to correspond with the grey shales of Kilcummin Head in Mayo, of 
the Bannah River in Fermanagh, of Monaduff in Longford, and of Ballinasereen 
in Londonderry; and when we consider that these shales are interstratified with 
calcareous strata which contain numerous fossils belonging to the upper members of 
the carboniferous limestone of Ireland, we must perforce class the whole series with 
the carboniferous limestone. Hitherto fossils of the genus Modiola have been con- 
sidered to belong to the Old Red Sandstone or Devonian system, but as he had dis- 
covered these fossils in great abundance as high up as the carboniferous slate, and 
far above the arenaceous limestone, he should include them among the fossils be- 
longing to the Carboniferous system; and hence, as these fossils have been met with 
in the red shales which alternate with red and gray sandstones and limestones near 
the bottom of the series, and among those strata which he had hitherto considered 
to belong to the upper portion of the Old Red system, he thought he was warranted 
in including them in the carboniferous series. 
From what he had said, the red colour of the sandstone beds can be no longer 
considered as indicative of age, as he had shown that in several localities the red 
sandstone and red conglomerate occur above the arenaceous limestone and ichthyo- 
lite beds. 
In following this view it will be difficult in some localities to determine the line of 
separation between the red sandstone of the Carboniferous and that belonging to 
another system which lies below; but in the northern counties a very decided line 
may be drawn, owing to the unconformability of the two systems. 
On the Old Red Sandstone, or Devonian and Silurian Districts of Ireland. 
By Ricnarp Grirritn, F.G.S, 
Mr. Griffith classed these two systems together owing to the difficulty he expe- 
rienced in some localities in the North of Ireland in separating strata, which from 
their fossils might be considered to belong to the Silurian system, from those which, 
