HIND : CARBONIFEROUS ROCKS OF ISLE OF MAN. 151 
the same Zaphrentis and caninoid Campophyllum, that they 
are all of one age. But the pros and cons of this important 
question are discussed more fully below. 
In our paper on the Carboniferous Succession below the^ 
coal measures in North Shropshire, Denbighshire, and Flint- 
shire, op. supra cit., Mr. Stobbs and I showed that the Lower 
Carboniferous rocks of the Bristol succession were not deposited 
in that area, and that the land only sank beneath the sea in 
late Seminula times. Mr. Cosmo Johns (Geol. Mag., Dec. 5, 
vol. iii., 1908, p. 320) showed that the horizon of the basement 
beds at Ingleboro' was probably that of the lowest Seminula 
times. It now appears that the Manx slates remained above 
water, probably as the shoulder of a mountain whose summits 
never sank below the Carboniferous sea, showing how long 
insular conditions have existed even for so small an area as 
Manxland. It is probable, however, that a much greater thick- 
ness of Carboniferous rocks may surround the island beyond 
its present shore-line, or even form part of it buried beneath 
the glacial deposits which form the lowlands of its northern 
portion. 
General Conclusions. 
During the last two or three years much research has been 
going on in various Carboniferous areas and I learned much 
from my work on the sequence in North Wales, in conjunction 
with Mr. J. T. Stobbs. The sequence there showed that 
there were two series of black limestones, one that of Teilia, 
characterised by Posidonomya Becheri, Pterinopecten papy- 
raceus, and a goniatite fauna, the other, the black limestones 
of Prestatyn, characterised by Zaphrentis Enniskilleni, and that 
the latter formed part of the Upper DibunophyUum zone. 
I had previously obtained Z. Enniskilleni from the black 
marble of Ashford, Derbyshire, and fron^i beds at Whitewell 
and Swinden Gill, Yorkshire, which were apparently just below 
the base of the Pendleside series. Also in the county of 
Limerick at the same horizon, immediately below the Pendle- 
side series of Foynes Island. 
