50 REPORT—1852. 
deposits which occur beneath the anthracite beds, it is probable that we may add 
5000 feet more to the Silurians which occur below the limestones containing fossils 
similar to the Llandeilo flags, making in all a total thickness of 30,000 feet of strata 
through which four distinct bands of deposits containing fossil remains are scattered. 
From the mineral character of these Silurians, and also from their occurrence below 
the limestone with lower Silurian fossils, it would seem that the great bulk of the 
Scotch Silurians are about the equivalents of the Longmynd beds of the governnment 
geologist, as shown in North Wales. But the Scotch deposits have, however, one 
feature which the Longmynd beds do not possess, viz. organic remains, and they are of 
such thickness as to indicate that in them are contained some of the lowest forms of 
life, not only as regards the relation of the fossils to animals generally, but likewise 
as respects geological position. 
With regard to the fossil contents of these lower Silurian beds, these are remark- 
ably simple, and at the same time very characteristic. Graptolites of various species 
are the almost exclusive fossils, and they abound more in the lower beds than in the 
higher strata. In the shales which lie above the anthracite they occur in great pro- 
fusion, and are the exclusive fossils of this deposit. Here, too, the greatest amount 
of species is obtained, as well as the greatest abundance of individuals; and as 
respects the latter, I know of no deposit in the whole range of the geological for- 
mations which can be compared with these black shales, so far as quantity of fossils is 
concerned. 
Although these low beds are characterized by this group of fossils, it is not sufficient 
to give to them a division distinct from the lower Silurians. Graptolites in some 
districts occur in considerable abundance, above beds which are marked by lower 
Silurian trilobites, as in Bohemia. Some species of Graptolites extend upwards into 
the upper Silurian, amongst which is the Graptolites priodon, Bronn; and this spe- 
cies is found in great quantities in the lower Silurians of Scotland, at Greistone, in 
the gray slates. But although I have examined many thousand specimens from the 
soft black shale above the anthracite, I have never been able to detect this common 
Graptolite. 

On the occurrence of Graphite at Almorness Head, Kirkeudbrightshire. 
By Rovert Harkness. 
At Almorness, a headland which lies on the west side of the entrance of the estuary 
of the river Urr, in the stewartry of Kirkcudbright, graphite occurs, This headland 
consists principally of syenite and patches of metamorphic lower Silurians. The 
syenite is a portion of that which extends from Criffel, a mountain on the south-east 
of Galloway, along the southern margin of the county, and crossing the estuary of the 
Urr, makes its appearance on the western side. In this syenite the felspar is com- 
monly of a white colour; but when the syenite approaches the Silurian rock, the 
felspar becomes reddish, giving the syenite a flesh-coloured tint. This is the case 
with that portion which forms the headland of Almorness, and through which veins 
of quartz traverse. In one of these, which occurs on the south-west side of the head- 
land, the graphite is found. This vein, which is about 4 feet wide, has the graphite 
disseminated through it. It likewise appears on the syenite in contact with the 
quartz vein. It has been urged by some of the German chemists, that the presence 
of plumbago in igneous rocks is due to the decomposition of carburetted hydrogen, 
which, passing over matter through veins in a red-hot state, has been decomposed, 
the result being the deposition of the carbon, which, uniting with iron in the rocks, 
appears in the form of a carburet of iron. So far as regards the former occurrence of 
carburetted hydrogen in connexion with the rocks which have been elevated by the 
irruption of the syenite in this locality, this is a circumstance extremely probable. In 
the Silurians which occur to the north ofthe district occupied by this syenite, there are 
seen extensive beds of anthracite; and these beds of anthracite, when acted on by 
gnecus matter previous to their becoming anthracitic, would afford abundance of 
hydrocarbons. 
Amongst the Silurians which are contiguous to the syenitic district, and which are 
much metamorphosed and chloritic, there occur beds, which, from their structure and 
position, appear to have originally been anthracite, but which now contain no traces 
ofcarbon. Probably the action of the igneous rocks on these beds may have been the 
