It is by no means safe to assume that these and such Upper Carboniferous sporangia as Bower[771] compared with those of _Todea_ were borne on plants possessing the anatomical characters of Osmundaceae rather than those of the extinct Palaeozoic family Botryopterideae. This brings us to the important fact, first pointed out by Renault, that the Botryopterideae are essentially generalised ferns exhibiting many points of contact with the Osmundaceae[772]. It is clear that whether or not we are justified in tracing the Osmundaceae as far back as the Lower Carboniferous period, some of the characteristics of the family were already foreshadowed in rocks of this age. Through a fortunate accident of preservation, unequivocal evidence of the existence of Osmundaceae in the Palaeozoic era is supplied by the Russian Upper Permian genera _Zalesskya_ and _Thamnopteris_. _Zalesskya._ This generic title has been instituted by Kidston and Gwynne-Vaughan[773] for two Russian stems of Upper Permian age, one of which was named by Eichwald[774] _Chelepteris gracilis_, but the probability that the type of the genus _Chelepteris_ is generically distinct from Eichwald’s species necessitated a new designation for the Permian fern. In habit the stem of _Zalesskya_ resembles that of an _Osmunda_ or a _Todea_, but it differs in the possession of a stele composed of a continuous cylinder or solid column of xylem surrounded by phloem, and by the differentiation of the xylem into two concentric zones. The leaves are represented by petiole-bases only; the sporangia are unknown. The stem and leaf-base anatomy fully justifies the inclusion of _Zalesskya_ in the Osmundaceae. _Zalesskya gracilis_ (Eichwald). Fig. 248.