Chap. XI.] 
UPPER DEVONIAN IN IRELAND. 
288 
There can, indeed, be no ambiguity in assigning to these vastly thick 
Irish rocks (d in the section p. 281), immediately and conformably sur- 
mounting the uppermost Silurian (c), their true stratigraphical place — 
particularly when we see that they are covered not only by a very full 
series of the Lower Carboniferous rocks (g, h), but also by intermediate 
red conglomerate and sandstone of great thickness (/), to which, in Ire- 
land, the term Old Eed Sandstone was once exclusively applied. 
This is the red conglomerate and sandstone (Ji) of the section, p. 178, 
which, in one tract, overlaps unconformably different members of the 
underlying rocks, and is itself conformably overlain by the Carboniferous 
rocks of the South of Ireland, and forms their natural foundation. See- 
ing the rupture between it and all that is subjacent, Mr. Jukes and other 
geologists were at one time led to class this red sandstone and conglo- 
merate with the Lower Carboniferous rocks, including the Yellow Sand- 
stone and Lower Limestone -shale and Slate of Griffith, to which it is con- 
formable ; but the characteristic fossils of the superjacent dark-grey 
and carbonaceous beds, such as Ehynchonella pleurodon and Spirifer cus- 
pidatus, have nowhere been detected in these red strata, — the only remains 
which might seem to connect them with the overlying Carboniferous strata 
being certain fragments of Plants apparently common to both, though of 
these, even, no mutual specific identity has yet been established. It must 
also be stated that these same beds, particularly in the district of Kil- 
torkan, contain species of fossils wholly unknown in the Carboniferous 
rocks. Such are some peculiar Lycopodiaceous plants, the Fern originally 
called Cyclopteris, now Sphenopteris (or Adiantites) Hibernica, and the 
large freshwater shell Anodonta Jukesii, Forbes. 
Fossils (76). Fossil Plant from the Yellow Sandstone op Ireland. 
Adiantites (Cyclopteris) 
Hibernica, Forbes, Re- 
port Brit. Assoc. 1852. 
From specimens in the 
Museum of the Greolo- 
gical Survey. 
The Plant figured here, Foss. 76, was described in 1852 (by Edward 
Forbes) as the remains of one of the oldest Tree-ferns then known to us, 
and as essentially distinct from any Plant of the Coal-period. 
Again, in these strata the teeth of a Dendrodus and one of the dermal 
plates of a Coccosteus have also been found, both of them Fishes known in 
the Old Red or Devonian period only. These beds, like the Upper Old 
Eed Sandstone in many other countries, simply form a natural transition 
into the Carboniferous system. 
