194 Proceedings of the Royal Society of Edinburgh. [Sess. 
Brachiopod fauna, identical with that found in the Hurlet Alum Shale of 
the West of Scotland. This is succeeded by the first Abden Limestone, 
9 or 10 feet thick, which is encrinital in its lower part, while its upper 
part is rich in marine fossils. The Brachiopod, Lammelibranch, and fish 
fauna of the shale lying below the first Abden Limestone, as well as the 
succession and general appearance of the group as a whole, is so like that 
seen on the shore at Charlestown railway station, that we do not hesitate 
for a moment in stating our belief that they are identical, and that the 
first Abden Limestone is the equivalent of the Cobbinshaw-Hurlet Lime- 
stone of the preceding part of this paper. 
Over the first Abden Limestone comes a few thin beds of shale, which 
are succeeded by the lava forming part of the small headland known as 
Hoch-Ma-Toch. On the top of the lava rest more shales, which pass up- 
wards into another marine limestone locally known as the second Abden 
Limestone. A group of dark shales occur below the second Abden Lime- 
stone, which carry a fauna similar to that found above the Blackhall 
Limestone in the West of Scotland. But the existence of a fossiliferous 
shale immediately above the limestone has not yet been determined. 
Stratigraphically this limestone should lie somewhere on the position of 
the Blackhall Limestone of the West of Scotland — that is, between the 
Hurlet Limestone below and the Main Hosie Limestone above — and this is 
clearly its position in the section under consideration, because it has below 
it the first Abden Limestone, which we have shown to be the equivalent 
of the Hurlet Limestone, and above it the Seafield Tower Limestone, which 
we believe to be the same as the thick Charlestown and Petershill Lime- 
stone, or the Main Hosie Limestone of the West of Scotland. 
Passing over something like 100 feet of shale and reddened sandstone 
we reach the Seafield Limestone. This limestone is about 50 feet thick, 
consisting of bands separated from each other by intercalations of shale. It 
can be followed inland to the quarries at Inverted, where it is practically 
identical, so far as its physical characters are concerned, with the section 
just described. The faunal assemblage shows it to be identical with the 
Charlestown and Petershill Limestone, as it contains similar species of 
corals, crinoids, polyzoa, brachiopods, lamellibranchs, gasteropods, cephalo- 
pods, and fishes, and is therefore upon the horizon of the Main Hosie 
Limestone of the West of Scotland. 
The Seafield Tower or Main Hosie Limestone is surmounted by a 
bed of shale, which is succeeded by a thick mass of false-bedded pink 
sandstone, on which Seafield Tower stands. Above this come calcareous 
shales, with limestone bands and nodules, which stratigraphically should 
