with Equisetaceae ; while in another direction they presented links of connexion with Cycads and Conifers.
Discussion.
Mr. Carruthers expressed his thanks for the amount of information given by Dr. Dawson, but was inclined to take a somewhat different view on some of the points mentioned. Some time ago he had, in a paper read to the Society, deduced from the internal structure of Stigmaria, the root of Sigillaria, that the latter was a true cryptogamous plant. He had since met with confirmatory evidence in a specimen of a fluted and ribbed Sigillaria, showing the internal structure oi Stigmaria. Mr. Baily, in Devonian strata in Ireland, had found the root, stem, branches, leaves, and fruit of a plant which could, with certainty, be correlated. The root was a Stigmaria, the stem a fluted Sigillaria, the branches and leaves like those of Lepidodendron, and the fruit that of a cryptogam allied to Lepidodendron. With regard to the American specimens cited by the author, he would not speak with certainty ; but he might suggest a different interpretation. The axis was probably foreign to the Sigillaria in which it was found, and was a true coniferous stem composed of pith, medullary sheath, and wood with medullary rays, and vascular bundles passing to the leaves. Plants growing in the interior of decayed Sigillarian stems had been mistaken for organic piths, though they belonged to two or three genera. Dr. Dawson's estimate of Calamites and allied genera essentially agreed with those which he held.
Dr. Dawson thought that the views of Mr. Carruthers and his
own might possibly be reconciled, and was not prepared to admit
that the plant discovered by Mr. Baily was a true Sigillaria. It
belonged, moreover, to the Devonian period, and not to the Carboniferous. He quite agreed with Mr. Carruthers in regarding the
stems as closely allied with gymnosperms. He insisted on the layer
at the base of the interior of the trunks of the erect Sigillarioe
affording evidence of the interior structure of the plant, inasmuch
as it consisted of the compressed and decayed inner tissues of the
tree. It was curious that similar specimens had not been found in
England ; but the structures of these plants certainly occur in the
English Coal, which, like that of Nova Scotia, rests on Stigmaria-
underclays ; and there were other instances of trees being common
in the Coal-measures of Nova Scotia which were extremely rare in
England ; and the same discrepancies were found between different
American coal-fields.
4. Notes on the Geology of Aeisaig, Nova Scotia. By the Rev. D. Honeyman, D.C.L., F.G.S., &c, Director of the Provincial Museum. With a Note by Prof. T. Rupert Jones, F.G.S.
[Abridged.]
In the year 1864 I communicated a paper to the Society on the Upper Silurian rocks of Arisaig and their fauna. I observed then
