_Asplenium Johnstrupi_ and afterwards as _Dicksonia Johnstrupi_[911] from the Cretaceous beds (Kome series) of Greenland are very similar to _Coniopteris hymenophylloides_. [Illustration: FIG. 272. _Coniopteris hymenophylloides._ Specimen from the Inferior Oolite, Scarborough; in the York Museum. [M.S.]] _Coniopteris quinqueloba_ (Phillips). Fig. 273. This species, originally described by Phillips[912] as _Sphenopteris quinqueloba_, is very similar in habit to _C. hymenophylloides_, differing chiefly in the smaller size of the leaf and in the narrower ultimate segments. The specimen shown in fig. 273, B, illustrates the form of the sorus and sporangia. [Illustration: FIG. 273. _Coniopteris quinqueloba_ (Phillips). A, × 2; B, considerably enlarged. From drawings supplied by Dr Nathorst.] _Coniopteris arguta_ (Lind. and Hutt.[913]). Figs. 274, 275, A. The sterile pinnae of this species bear pinnules of a type met with in various species of ferns from different horizons; the smaller ones are entire and slightly falcate, while on the lower part of a frond the ultimate segments are longer and have a crenulate margin. The fertile pinnae bear pinnules reduced to a midrib with a narrow border, and terminating in a cup-like indusium (fig. 275, A). In habit the sterile leaf (fig. 274) of this species is similar to the Jurassic Schizaeaceous fern _Klukia exilis_. _Protopteris._ Presl[914] instituted this genus for a Lower Cretaceous tree-fern from Bohemia originally figured as _Lepidodendron punctatum_[915] and assigned to a Palaeozoic horizon; it was afterwards named by Corda[916] _Protopteris Sternbergii_ and referred by Brongniart[917] to _Sigillaria_. The genus _Protopteris_ stands for fossil fern-stems with the habit and, in the main, the structural features of recent tree-ferns. Persistent leaf-bases and sinuous adventitious roots cover the surface of the stems: the vascular system is of the dictyostelic type characteristic of _Cyathea_ (fig. 240, p. 313) and _Alsophila_. It is by the pattern formed by the vascular tissue on the exposed surface of the leaf-bases that _Protopteris_ is most readily recognised: the leaf-trace has a horse-shoe form with the ends curled inwards and the sides more or less indented (fig. 277). The generic name _Caulopteris_ is used by some authors in preference to Presl’s genus; but _Protopteris_ is more conveniently restricted to Mesozoic Cyatheaceous stems and _Caulopteris_ to Palaeozoic stems, with the internal structure of _Psaronius_ (see Chap. XXIII.). Stenzel applies _Caulopteris_ to Mesozoic stems in which the leaf-trace consists of several separate strands and not of a continuous band. [Illustration: FIG. 274. _Coniopteris arguta._ (Nat. size. From a specimen in the Sedgwick Museum, Cambridge.)] [Illustration: FIG. 275. A. _Coniopteris arguta._ (Fertile pinnae; nat. size.) B. _C. hymenophylloides._