In 1831 Mr Witham[340] published an anatomical description of a fragment of a _Lepidodendron_ which he named _Lepidodendron Harcourtii_ after Mr C. G. V. Vernon Harcourt from whom the specimen was originally obtained. The fossil was found in rocks belonging to the Calciferous series in Northumberland. Witham reproduced the account of this species in his classic work on _Fossil Vegetables_[341], and Lindley and Hutton[342], who examined Mr Harcourt’s material, published a description of it in their _Fossil Flora_ in which they expressed the view that _Lepidodendron_ is intermediate between Conifers and Lycopods. Adolphe Brongniart[343] included in his memoir on _Sigillaria elegans_ an account of Witham’s species based on material presented to the Paris Museum by Mr Hutton and Robert Brown. Dr Kidston[344] has shown that the actual transverse section figured by Witham is now in the York Museum; a piece of stem in the same Museum, which is not the specimen from which Witham’s section was cut, supplied the transverse section figured by Brongniart. The figures given by Lindley and Hutton do not appear to have been made from the York specimens. In 1887 Williamson[345] published a note in which he pointed out that some of the specimens described by him as _L. Harcourtii_ should be transferred to a distinct species, which he named _L. fuliginosum_. Subsequently in 1893 he gave a fuller account of Witham’s species; it has, however, been shown by Dr Kidston and by Mr Watson[346] that certain specimens identified by Williamson as _L. Harcourtii_ differ sufficiently from that type to be placed in another species, for which Watson proposes the name _L. Hickii_. A paper on _L. Harcourtii_ published by Bertrand[347] in 1891 extends our knowledge of this type in regard to several anatomical details. It was recognised by Williamson that the absence of secondary wood in shoots possessing the anatomical characters of _L. Harcourtii_ is a feature to which no great importance should be attached. It is possible that the large stems from the Isle of Arran described by Williamson[348] as _Lepidodendron Wünschianum_, in which the secondary wood is well developed, may be specifically identical with the smaller specimens from Northumberland and elsewhere which are recognised as examples of Witham’s type.