403 TRANSACTIONS OF THE GEOLOGICAL SOC. OF GLASGOW. 
fern, the Sphenopteris affinis, being in great abundance in some 
parts, and Calamites canneformis equally plentiful in other parts ; 
while very sparingly appeared the fern, Pecopteris dentata. On 
the top of the fossiliferous part of the shale I found a piece of tree 
stem, but not sufficiently preserved to allow of it being identi- 
fied. I wish here to say that I am much indebted to Mr. John 
Young, F.G.S., to whom I submitted specimens, for his kindness | 
-in examining and identifying the species named. As the changes 
that have taken place in the structure of the tree stem are rather 
interesting, I shall take the liberty of quoting what Mr. Young 
says :—“ No. 1 is a portion of a squeezed stem of what I think 
has been some coniferous plant. It has been very much bitu- 
minized so as to have lost all trace of its original woody structure, 
and has been subsequently altered by heat, so that it now 
gives very little flame. I noticed it contains some minute crystals 
of iron pyrites, and some fissures are filled with green carbonate 
of copper (malachite), which is elsewhere found in the Gourock — 
beds.” 
Now, before proceeding further, I will try to point out as near 
as possible where the fossil-bearing shale occurs, and the section 
herewith [Plate X VII.] will help me in doing so. The road for some 
distance past the Cloch Lighthouse closely skirts the shore, but 
proceeding we come to a place where the road bends a little 
inland, while the shore bends for a short distance rapidly out- 
wards, so that a gradually widening field is situated between the 
shore and the road, as indicated by the section. Where the shore 
and the road thus part company we find the shale above referred 
to. The bed is fully three feet thick, with sandstone above and 
below, and dips to the north-east with an inclination of about 20 
degrees, ouly half (the lower half) being fossiliferous. It is very 
friable, so that it is almost impossible to lift a large piece of it, 
and even when we do get a moderate-sized bit, we find that in 
drying it is very apt to break up into small fragments. I have 
already said that the structure of the piece of tree stem found 
in this shale has been very much altered; the alteration of the 
vegetable structure and also the friable condition of the shale 
itself having been probably caused by the action of the trap-dyke 
which is found about 30 or 40 yards to the south [Plate XVII., 
sec. 2]. The upper part of the shale is, so far as I can make out, 
entirely destitute of fossils. Wishing to know if the traces of 
