538 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 
called Navan Fort, one mile anda half west of Armagh. The face of the rock 
worked is sixty feet in height. The fish remains are found principally in the upper 
beds. 
At Tullyard,west of Wilson’s Bridge, on the Ulster Railway, the Lower Limestone 
is extensively quarried: the beds dip 8.W., at an angle of 30° to 40. They have 
the usuai character of the limestone in this district, varying from one to three 
feet in thickness separated by shales. The limestone ranges from a bluish gray 
to a brown colour, and is mostly of a crystalline texture. It contains numerous 
fossils. 
The Carboniferous Limestone of the Souwth-eastern portion of Ireland presents 
some variations from the series of strata composing the formation around Armagh. 
It consists mainly of three groups (see the section fig. 2), but the lower Limestone 
is frequently dolomitized either by the admixture of carbonate of magnesia during 
deposition or by a subsequent change in its character. The Limestone Series are 
separated from the Silurian beds by great thicknesses of Old Red Sandstones, 
attaining in some instances a vertical extent of more than 3,000 feet. These rest 
unconformably on the Silurian rocks, whilst above the sandstones are an additional 
200 feet of shales beneath the base of the limestones. The following is the series 
as developed in the district around Wexford and Waterford. 
Upper Limestone. 
““Calp”’ series. 
Lower Limestone (sometimes Dolomitic.) 
Lower Limestone Shale: 
Upper Old Red or “ Yellow Sandstone.” 
Old Red Sandstone. 
Lower Silurian Beds. 
The Old Red Sandstone is composed for the most part of breccias and conglomerates 
of well-rounded pebbles of grits, slates and quartz cemented together, with occasional 
thick beds of shale and sandstone of a reddish-brown colour. Above these are the 
yellow sandstones separated by an arbitrary line, indicated by a change in colour ; 
they vary from 200 to more than 500 feet in thickness. Occasionally the remains 
of plants are found in the shales of the Yellow Sandstone series. 
The uppermost beds of the Yellow Sandstone series at Hook point pass gradualiy 
into the Lower Limestone shales, and from them into the Lower Limestone. The 
yellow and greenish sandstone and shales change to dark gray, sandy, calcareous 
shales and thin grits, alternating with occasional seams of black chert and impure 
gray limestone. ‘These are followed by limestones, and in a thickness of about 200 
feet the shales and sandy portions disappear altogether. The beds are throughout 
fossiliferous, Spirifer, Orthis and Strophonema, Encrinites and Fenestella serving to 
distinguish the beds of Carboniferous age. The Lower Limestone is generally 
erystalline, thick-bedded, regularly jointed, and of a dark gray colour. In some 
