_Fossils described by authors as being closely allied to_ Psilotum. A search through palaeobotanical literature reveals the existence of a very small number of specimens which have been identified as representatives of the Psilotales. An inspection of the material or published drawings leads one to the conclusion that practically no information of a satisfactory kind is available in regard to the past history of the two southern genera _Psilotum_ and _Tmesipteris_, which are regarded by some botanists as relics of an ancient branch[51] of pteridophytes. [Sidenote: PSILOTITES, ETC.] In 1842 Münster[52] instituted the genus _Psilotites_ for a small impression of a slender branched axis from Jurassic rocks near Mannheim in Germany which he named _Psilotites filiformis_; Schimper[53] spoke of the specimens as too doubtful for determination, an opinion with which every botanist would cordially agree. Goldenberg’s species _Psilotites lithanthracis_[54] from the Saarbrücken coal-field is founded on impressions of axes: some of these are dichotomously branched and bear small oval projections, which may be rudimentary leaves or possibly leaf-scars. More recently Kidston[55] described specimens of branched axes from the Lanarkshire coal-field bearing a row of lateral thorn-like projections under the title _Psilotites unilateralis_; but these fragments, as Dr Kidston himself admits, are of no botanical value. In a paper on fossil Salvinias, Hollick[56] mentions _Salvinia reticulata_, originally described by Heer and by Ettingshausen and _S. Alleni_ Lesq.[57] a Tertiary species, and calls attention to their very close resemblance in form, nervation, and apex to the leaves of the genus _Tmesipteris_: he refers both species to that genus. The drawings reproduced by Hollick represent leaves with a midrib and numerous anastomosing lateral veins, whereas in _Tmesipteris_ the lamina of the leaf has a midrib without lateral branches. An enlarged drawing of the outlines of the epidermal cells would correspond closely with the small reticulations in the fossil leaves and it may be that there has been some confusion between veins and cell-outlines. In any case there would seem to be no reason for the use of the recent generic name[58]. Among other fossils assigned to the Psilotales we have Marion’s genus _Gomphostrobus_ from the Permian of France and Germany[59]. Marion placed this plant in the Coniferales on the strength of its resemblance to _Walchia_ and _Araucaria_, but Potonié[60] is inclined to recognise in the leaves and monospermic sporophylls characters suggestive of Lycopodiaceous affinity.