_Protopteris Witteana_ Schenk[926] (fig. 278, G, H), a Wealden species recorded from Germany and England, represents a closely allied or possibly an identical type. The section of the stem (fig. H) shows the narrow vascular bands, x, of a dictyostele similar to that of recent Cyatheaceous tree-ferns and a form of meristele (fig. G, x) resembling that of _P. punctata_. Adventitious roots are seen in section at R (figs. G and H). =Polypodiaceae.= Sections of petrified sporangia from the English Coal-Measures (_Pteridotheca_ sp.) occasionally exhibit a striking resemblance to those of recent Polypodiaceae[927], but in the absence of material in which it is possible to recognise the true orientation of the sporangia, the exact position of the annulus is almost impossible to determine. We have as yet no satisfactory evidence of the existence of true Polypodiaceae in the Palaeozoic era. It is noteworthy that apart from the absence of ferns which can reasonably be included in this family, the anatomical features of the Botryopterideae (Coenopterideae) and of the Cycadofilices or Pteridosperms do not foreshadow those of Polypodiaceous ferns. On the other hand, as we have already noticed, anatomical characters of such families as the Gleicheniaceae, Hymenophyllaceae, and Schizaeaceae are met with in certain generalised Palaeozoic types. These facts are perhaps of some importance as supplying collateral evidence in favour of the relatively more recent origin of the dominant family of ferns in modern floras. [Illustration: Fig. 279. A. _Adiantides antiques_ (Ett.). (½ nat. size.) B. _A. Lindsayoides_ (Sew.). (B′ nat. size.) (A, after Kidston.)] The use of the generic name _Adiantites_ for fern-like fronds of Lower Carboniferous age characterised by cuneate pinnules like those of species of _Adiantum_, suggests an affinity which is in all probability non-existent. It has been pointed out that this generic name was applied in the first instance to the leaves of the Jurassic plant _Ginkgo digitata_[928] and should, therefore, be discarded. Schimper[929] used the designation _Adiantides_, and Ettingshausen[930], more rashly than wisely, preferred _Adiantum_. The specimens described by Kidston[931] as _Adiantides antiquus_ (Ett.) (fig. 279, A) from the Carboniferous limestone of Flintshire are portions of tripinnate fronds bearing cuneate segments with numerous forked veins radiating from the contracted base of the lamina. It is not improbable, in view of Dr White’s[932] discovery of seeds on a very similar plant from the Pottsville beds of North America, that this characteristic Lower Carboniferous genus is a Pteridosperm.