Various opinions have been expressed in regard to the nature of the Devonian species _Haliserites Dechianus_ Goepp. with which Carruthers[70] identified Miller’s Old Red Sandstone plant: reference may be made to a paper by White[71] containing figures of dichotomously branched impressions described as species of _Thamnocladus_ which he includes among the algae. In describing some Belgian impressions of Devonian age as _Lepidodendron gaspianum_ Daws. Crépin[72] states that Carruthers has come to regard the specimens named by him _Psilophyton Dechianum_ as branches of a Lepidodendron; he also quotes Carruthers as having expressed the opinion that the name _Psilophyton_ had been employed by Dawson for two kinds of fossils, some being twigs of _Lepidodendron_ while others, identified by Dawson as the reproductive branches of species of _Psilophyton_, represent the spore-cases of ferns comparable with Stur’s genus _Rhodea_[73]. One of the examples figured by Carruthers[74] as _P. Dechianum_ from Thurso (preserved in the British Museum, no. 52636), measuring 34 cm. in length and 8 mm. broad, bears a close resemblance to a fern rhizome covered with ramental scales such as that of a species of _Davallia_. Other Belgian specimens described by Gilkinet[75] as _Lepidodendron burnotense_, like Crépin’s species, are no doubt generically identical with some of the Scotch and Canadian fossils placed in the genus _Psilophyton_, though Penhallow[76] considers that the species _Lycopodites Milleri_ is more correctly referred to _Lycopodites_ than to _Psilophyton_. A more recent paper on the Geology of the Perry basin in South-eastern Maine by Smith and White[77] contains a critical summary of the literature on _Psilophyton_ and drawings of specimens. The latter afford good examples of Pre-Carboniferous plant fragments, such as are often met with in various parts of the world, which conform in habit to the New Brunswick specimens made by Dawson the type of his genus. An examination of material in the Montreal Museum and of Hugh Miller’s specimens in the Edinburgh collection leads me to share the opinion of Count Solms-Laubach that the name _Psilophyton_ has been applied to plants which should not be included under one generic title. As Kidston[78] pointed out, the Canadian species _Psilophyton robustius_ is not generically distinct from British and Belgian specimens referred to _Lepidodendron_; it may possibly be identical with the Bohemian plants on which Stur founded his genus _Hostinella_[79]. The Devonian plants described by Stur have since been examined by Jahn[80] who regards them as vascular plants, and not as algae to which Stur referred them; he mentions two species of _Psilophyton_ but gives no figures.