TRANSACTIONS OF THE SECTIONS. 45 
sandstone and some thin beds of impure limestone: its thickness may be about 500 
_ feet. The upper or third division consists of red sandstones and red conglomerate, 
_ brownish-red, and greenish- and yellowish-white shales frequently passing into marl, 
and containing numerous bands of light gray nodular limestone, and occasionally 
arenaceous and sometimes conglomeritic limestone, above which is a thick series of 
: beds of dark gray shale, which at Cullion forms the upper portion of the series. 
No fossils have been found in the lower division; the second, or black shale divi- 
sion, contains numerous fossils, particularly several varieties of Cythere, Modiola 
Macadami, Cypricardie, Murchisonia elongata, and several kinds of fishes, especially 
Gyracanthus and Holoptychius, several of which have been described by Capt. Port- 
lock, but many have not been noticed by him. The thin limestone bands in the 
White Water abound with obscure Atrypas, apparently the Atrypa gregaria, which 
_ also abounds in Ballington, near Ballycastle, in the county of Mayo. 
_ The third, or upper division, which is about 1400 feet thick, contains no fossils ; 
___ but the gray quartzose and conglomerate limestone which succeeds it contains Orthis 
: crenistria, O. filiaria, Spirifera bisulcata, S. attenuata, Bellerophon apertus, Lithoden- 
dron, Fenestelle, and other fossils of the carboniferous limestone, while the shale 
which succeeds this produces a profusion of similar fossils, together with many others 
which usually occur in the upper shales of the calp. 
This remarkable deposit of sandstones and shales, which occurs in the valley of 
Ballinascreen, differs in some respects from the districts of yellow sandstone already 
‘described, in its containing no thick series of beds of fossiliferous limestone ; but the 
occurrence of certain fossils, as Modiola Macadami, Holoptychius Portlockii, and ten 
-or twelve species of Cythere similar to those found elsewhere, prove that they belong 
to the series of shales which accompany the arenaceous limestone of the north coast 
‘of Mayo, and in the district of Pettigoe, north of Lough Erne. 
~ Another locality in which the same fossils occur is the carboniferous valley of Bal- 
‘linamore in the county of Leitrim, situated between the Cairn Clon Hugh mountains 
of the county of Longford, and the millstone grit district of Slieveaneerin in the county 
‘of Leitrim. The strata of this valley comprehend the entire suite of the Carboni- 
ferous Limestone system of Ireland. 
~ Commencing from below, as exhibited in the section of the valley, we have the 
greywacke slate of Cairn Clon Hugh succeeded unconformably by thin beds of red 
sandstone conglomerate, followed conformably by yellowish-gray conglomeritic 
sandstone, on the top of which are beds of impure arenaceous limestone and dark gray 
shale, with a few thin beds of dark gray sandstone, altogether about’seventy feet in 
thickness. These are followed by 150 feet thick of yellowish-gray quartzose sand- 
stone, succeeded by argillaceous limestone, alternating with thin beds of dark gray 
shale and gray calcareous sandstone; about 100 feet above which is the carboniferous 
slate, lower limestone, calp and upper limestone in regular succession, the latter being 
covered by the millstone grit series of Slieveaneerin mountain. 
In the lowest calcareous strata noticed in this section, particularly in the lands of 
' Monaduff in the county of Longford, were discovered numerous species of Cythere ; 
also in abundance Modiola Macadami, and several plants, together with fish-spines 
_ not described, and beautiful specimens of Oracanthus Milleri, perfectly identical with 
/ that found in the Bristol limestone, and several specimens of Ctenacanthus. The 
second limestone above the shale also contains plants, some resembling Lepidoden- 
a -drons of the coal series, but of a new species. The upper beds of this limestone con- 
tain Orthis crenistria in great abundance, and other fossils of the limestone series. 
_ The carboniferous slate which succeeds these strata contains the Fenestellz, and the 
other fossils characteristic of that division of the limestone series, as do also the lower 
_ limestone, calp, and upper limestone of Slieveaneerin. 
Referring to a small district of red sandstone, gray shale, and yellow and red lime- 
_ stone which occurs at Cultra, on the southern shore of Belfast Lough in the county 
~ of Down, Mr. Griffith said the strata of this locality had previously been considered 
_ by him and other geologists to belong to the new red sandstone and magnesian lime- 
stone group, but from a careful examination he had made of its strata and fossils 
___-within the last year, he was now decidedly of opinion that they are coeval with the 
_ valley of Ballinascreen. The section of the strata consists first of a base of the well- 
| _ known greywacke of the county of Down; its strata are succeeded unconformably 
| a Ye 

