1822. _Stigmaria ficoides_, Brongniart, Mem. Mus. d’hist. nat. Paris, Pl. XII. fig. 7, p. 228. 1825. _Ficoidites verrucosus_, Artis, Antediluvian Phytology, Pl. X. 1840. _Stigmaria anabathra_, Corda, Flor. der Vorwelt, Pl. XIV. The first figure of _Stigmaria_ is said to be by Petver in 1704; Volkmann published illustrations of this common fossil in 1720 and Parkinson in 1804[566]. Binney, whose researches may be said to have inaugurated a new era in the investigation of fossil plants, wrote in 1844: “Probably no fossil plant has excited more discussion among botanists than the _Stigmaria_. It is the most common of the whole number of plants found in the Coal-Measures, but there has hitherto been the greatest uncertainty as to its real nature[567].” This uncertainty still exists, at least in the minds of some who know enough of the available data to realise that our knowledge is imperfect. To pass to the questions of the affinity and nature of _Stigmaria_: Brongniart[568] at first compared his genus with recent Aroideae, but he afterwards[569] spoke of it as probably the root of _Sigillaria_. Other writers regarded _Stigmaria_ as a dicotyledonous plant comparable with Cacti and succulent Euphorbias. For many years opinion was divided as to whether _Stigmaria_ represents an independent and complete plant or the underground system of _Sigillaria_. Artis[570], Lindley and Hutton[571], as well as Goldenberg[572], believed it to be a prostrate plant unconnected with any erect aerial stem. Goldenberg figured one of the slender rootlets terminating in an oval body described as a reproductive organ. This seed-like impression is either some extraneous body or an abnormal development at the end of a rootlet. In 1842 Logan drew attention to the almost complete monopolisation by _Stigmaria_ of the underclays, the rock which as a general rule occurs below a seam of coal. He wrote: “The grand distinguishing feature of the underclays is the peculiar character of the vegetable organic remains; they are always of one kind (_Stigmaria ficoides_) and are so diffused throughout every part of the bed, that by their uniform effect alone the clay is readily recognised by the eye of the miner[573].” This fact, which has played a very conspicuous part in the perennial discussions on the origin of coal, led to the almost general recognition of the underclays as surface-soils of the Coal period forests. The next step was the discovery of _Stigmaria_ in the Coal-Measures of Lancashire and in the Carboniferous rocks of Cape Breton, Nova Scotia, forming the basal branches of erect stems identified by Binney[574], Bowman[575] and Richard Brown[576] as undoubted Sigillariae. In one case Brown found what he considered to be convincing evidence of the continuity between _Stigmaria_ and _Lepidodendron_.