Many eminent geologists have long entertained the opinion, that Stigmariæ are nothing more than the roots of Sigillariæ, and this opinion has been supported by so many recorded cases during the last two or three years, amongst which I may include one from the Sydney coal-measures, an account of which appeared in the 8th Number of the Journal of the Geological Society, that I think no further doubts can remain concerning the real nature of those fossils. Since I forwarded to the Society a description of the Sydney Sigillaria about twelve months ago, I have discovered several upright trees in the coal-measures, evidently not Sigillariæ, with roots of Stigmariæ united to them. These trees exhibited so many of the peculiar characteristics of Lepidodendron, that I at once concluded they belonged to that genus; but having never even seen it hinted that Lepidodendron possessed Stigmaria roots, and distrusting my own skill in fossil botany, I determined to wait until I could collect more decisive evidence in confirmation of my opinion. This evidence I have now obtained in another example, fortunately most complete in all its parts, a description of which I hasten to lay before the Society, accompanied with sketches, which I hope will clearly prove that the stem in question is a genuine Lepidodendron united to roots of Stigmaria.