The Upper Carboniferous species _Dicksonites Pluckeneti_, of which Sterzel[898] described fertile specimens in 1886 as possessing circular sori, has since been shown by Grand’Eury[899] to be a Pteridosperm bearing small seeds. In _Sphenopteris_ (_Discopteris_) _cristata_ (Brongn.) Zeiller[900] has described sori very like those of _Cyathea_ and _Alsophila_, but differing in the exannulate sporangia: this species, like so many of the Palaeozoic ferns, is probably more akin to the Marattiaceae than to the Cyatheaceae. We have as yet no satisfactory evidence of the existence of the Cyatheaceae in Palaeozoic floras. It is not until we reach the Jurassic period that trustworthy data are obtained. Raciborski[901] has identified as Cyatheaceous fertile Jurassic fronds from Poland, but his figures are inconclusive. In _Alsophila polonica_ it is not clear whether the annulus is vertical or oblique, and in another supposed member of the family, _Gonatosorus Nathorsti_, in which the indusium is described as bivalvate, there is no proof of affinity to Cyatheaceae. In attempting to decipher the past history of the Cyatheaceae it is important to remember the close resemblance between the fertile segments of some species of _Davallia_ (Polypodiaceae) and those of _Dicksonia_ (fig. 229, C, D, p. 294). Unless the sporangia are well enough preserved to show the position of the annulus, it is frequently impossible to feel much confidence in the value of the grosser features, such as the reduced lamina of the fertile segments and the form of the sori. It is, however, probable that the widely-spread Jurassic species _Coniopteris hymenophylloides_ is correctly referred to the Cyatheaceae, but even in the case of this species the evidence of external form needs confirmation by an examination of individual sporangia. _Coniopteris._ This genus was instituted by Brongniart[902] for fossil fronds characterised by pinnules more or less intermediate between the _Pecopteris_ and _Sphenopteris_ type and agreeing in the form of the sori with the leaves of recent species of _Dicksonia_. It should be noted that Stur included in this genus a species, _Coniopteris lunzensis_[903] from the Upper Trias of Lunz, which he regarded as a Marattiaceous fern. _Coniopteris hymenophylloides_, Brongn. Figs. 271, 272, 275, B. 1828. _Sphenopteris hymenophylloides_, Brongniart, Hist. vég. foss. p. 189, Pl. LVI. fig. 4. 1829. _S. stipata_, Phillips, Geol. York. p. 147, Pl. X. fig. 8. 1835. _Tympanophora simplex_, Lindley and Hutton, Foss. Flor. Pl. CLXX. A. — _T. racemosa_, _ibid._ Pl. CLXX. B. — _Sphenopteris arguta_, _ibid._ Pl. CLXVIII. 1836. _Hymenophyllites Phillipsi_, Goeppert, Foss. Farn. p. 256. 1849. _Coniopteris hymenophylloides_, Brongniart, Tableau, p. 105. — _Coniopteris Murrayana_, _ibid._