148 
JOURNAL OF THE GEOLOGICAL SOCIETY OF DUBLIN. 
stones, and coarse red shale, succeeded conformably by gray mica¬ 
ceous sandstones, gray conglomerate, and dark gray shale, Avith 
yellow and white sandstones alternating with reddish argillaceous 
sandstones,—the entire series being characterized by the presence 
of imperfectly preserved remains of plants, which invariably occur 
in the gray and white micaceous layers of sandstone, and never in 
the red sandstone and shales which alternate with them. In one 
locality on the western side, these remains become so numerous as 
to constitute thin seams of anthracite, from one to two inches in 
thickness. The fossil plants, although very imperfectly preserved, 
present a general resemblance to the forms of fossil plants found at 
Tallowbridge, in beds of similar age, some of which were figured by 
me in my account of the fossil plants of the lower Carboniferous 
period. Some of the most common of the Hook plants are figured 
in the annexed Plates. 
Figure 1 represents the imperfectly preserved exterior of Knor- 
ria dichotoma , in which the spiral arrangement of the leaflets is 
traceable, although almost obliterated. 
Figures 2 and 4 represent natural casts of the interior of the 
same plant; and figure 3, a cross section of same, showing the ex¬ 
istence of a central axis, as in Stigmaria. The central axis was 
connected with the outer stem by a remarkable series of spirally 
arranged woody spiculae, which are shown in figures 2 and 4. 
Figures 5 and 6 show smaller branches of the same plant; in 
these, however, the spiral arrangement of the leaflets is not visible; 
and it is possible they may be the remains of a distinct form. 
The total thickness of these plant beds is 382 feet. The gray 
and yelloAV sandstones which contain the plant remains were evi¬ 
dently brought from a quarter different from that which supplied 
the red sandstones and occasional conglomerate beds Avhich are found 
with the plant beds. We may suppose these vegetable remains to 
have been brought from a distance, and deposited with the red 
sandstones in a sea which was probably growing deeper, and which 
ultimately became the receptacle of exclusively marine remains. 
3- OLDER LIMESTONE. 
We find the plant sandstones just described succeeded by a thick 
series (851 feet) of alternating beds of arenaceous limestone, black 
