4 
PROCEEDINGS OF SOCIETIES. 
Conglomerates, which would occupy an unconformable and superior po¬ 
sition, by a note to that effect on my Geological Map. I may also observe, 
that their unconformity with the overlying red and carboniferous beds 
was noticed at the same early period, though, in conformity with the 
established ideas which have grown with our growth, I did not make 
the sacrilegious attempt, either at that time or since, of uniting the 
brownish-red beds with the Silurian series on the one hand, or, on the 
other, of neglecting the distinction between the inferior conformable red 
strata and the undoubted Carboniferous rocks of the north of Ireland. 
At the Meeting of the British Association held in Belfast, in the 
year 1852, I brought forward a communication relative to the Yellow 
Sandstone as developed on the north shore of the county of Mayo; ex¬ 
hibiting at the same time a complete suite of Carboniferous fossils, which 
had been collected from these rocks; and I remember having been much 
impressed by the remarks of Sir H. de laBeche and Mr. Jukes, who 
had visited that locality immediately prior to the Meeting. They ad¬ 
vised me to omit from my Map a district I had marked as Old Bed Sand¬ 
stone, saying that by so doing I would strengthen the case of the 
Yellow Sandstone; as that, from their observation of that locality, it 
would not appear that any true Old Bed Sandstone existed, and accord¬ 
ingly I had expunged my boundary and letter P. But as it would have 
become necessary to extend this generalization all over the north of 
Ireland, and not being in a position of doing so, owing to my inability 
at the time of making a personal examination, I afterwards thought it 
better to let it remain on the Map for the present: subsequently, how¬ 
ever, examinations made by myself, and others connected with me, 
under my direction, brought to light Carboniferous plants, and even 
Mollusca, far below the boundary I had originally drawn, in black 
shales, gray sandstones, and conglomerates, so that I became convinced 
that there was a very slight development, if any, of the true Old Bed 
Sandstone in the north of Ireland. I may allude to the occurrence of 
such plants as Sigillaria, with ferns, and Stigmaria fico'ides, discovered 
within the boundary of these Old Bed beds, as laid down on my Map, 
particularly at Mac Swine’s Bay, situate on the north shore of the Bay 
of Donegal, amongst which I would call attention to the remarkable 
Stigmaria now in the courtyard of the Boyal Dublin Society. These 
plants were declared to be Carboniferous by M. Adolphe Brongniart, to 
whom some of them were sent, and his letter on the subject may be 
seen in a late Number of the Journal of our Proceedings. On the 
north coast of Mayo, likewise, the same plants occur, mingled with 
Mollusca and fish remains, and are found very low down in the series, 
in the yellow, and even red shales at Glenbehy Biver, as well as in the 
shales and arenaceous limestones of Bunnatrahir Bay and Carrowcor. 
This being the case, it would appear that most, if not all, of the red 
beds of the north of Ireland, should be classed with the Carboniferous 
system, both from their conformability and their fossils ; while their un- 
conformability with the brownish-red grits and conglomerates of the 
three districts I have mentioned, sufficiently separates them from being 
