152 
JOURNAL OF THE GEOLOGICAL SOCIETY OF DUBLIN. 
of the deposition of the red conglomerate, had now reached its 
greatest depth, and had become the residence of creatures accustomed 
to provide their food in regions of the ocean remote from land. The 
following list, although far from perfect, contains the most common 
forms of fossil remains found in the limestone beds above the 
dolomite:— 
Turbinolia fungites. Cyrtia laminosa. 
Favosites megastoma. Athyris concentrica. 
Fenestellidae. Athyris squamosa. 
Spirifer speciosus. 
Sp. clathratus. 
Productus Scoticus. 
Orthis crenistria. 
O. filiaria. 
Palseechinus ellipticus. 
Actinocrinus triakontadactylus. 
Poteriocrinus punctatus. 
Psammodus porosus. 
Ctenacanthus. 
It would be easy to add to the foregoing lists; but I have 
been more anxious to give an exact account of the species found, 
whose locality is certain, than to give a larger list, with a less pre¬ 
cise determination of locality. In the lists already given the precise 
position of each is certain, and this circumstance gives a value to 
the catalogue which it would not otherwise possess. 
It is necessary, in conclusion, to say a few words on the geolo¬ 
gical age of the entire group and its subdivisions. The occurrence 
of such fossils as Athyris concentrica , Athyris squamosa , Spirifer clath¬ 
ratus (which I believe to be only a variety of the Spirifer disjunctus , 
or S. Verneuilli ), is sufficient to determine the position of the lime¬ 
stone beds as belonging to the lower portion of the Carboniferous 
system. The plant beds are the Yellow Sandstone of Dr. Griffith, 
or the Upper Devonian of the Geological surveyors. One of Mr. 
Griffith’s divisions is lithologically absent, viz., the Carboniferous 
slate; but it is represented paleontologically by the entire limestone 
group. It is not possible to identify, bed by bed, the series here 
described with any system of subdivision proposed for the lower 
Carboniferous system; but I think no person, considering the 
district fairly and fully, can avoid coming to the conclusion that 
any line drawn in it must be arbitrary, and particularly so one sepa¬ 
rating the lower portion as Devonian from the upper as Carboni¬ 
ferous, when not a single characteristic Devonian fossil has been 
