THE tree trunk from which this slice was taken was found in the railway cutting on the Forth Bridge extension of the North British Railway, near Wester Dalmeny, by Mr. Thomas Kerr, inspector, and was placed by him on the platform of Gorgie Station, where I first saw it. I recognised it at once as a Carboniferous tree, similar to those I had seen at some of the ironstone pits near Glasgow, but much larger than any of them, several of the pieces being about 14 inches in diameter, and 7 or 8

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... in thickness. The outside bark was intensely black where perfect, and yellowish where scaled by weathering. Inside the bark was a layer of white chalky-looking material, with a circlet of black matter within it. On examination with my lens I found that the latter consisted of a lacework of cells, with lines radiating from the centre, which showed it to be the core of the tree, the structure being preserved as in life. I therefore thought that the specimen would be a prize for the Geological Survey collection in the Museum of Science and Art in Edinburgh. But to make quite sure that I was right in my identification I asked Mr. Robert Kidston, F.G.S., to go to Gorgie and see the tree for himself. On his visit Mr. Kerr handed him over the specimen, and he at once took possession, and carried it off to the marble-cutting works of Messrs. M'Glashen & Sons at Canonmills, to be cut and polished. This they did admirably, and not only was the character of the tree as a Lycopod made clear, with its core or heart, but the chalky matter underlying the bark was shown to be volcanic ash, and to consist of pellets and dust, such as were thrown out of the small volcanic necks or vents which pass often through the Carboniferous rocks.