On the ground of their general anatomical features _Lepidocarpon_ and _Miadesmia_ are clearly entitled to be included among extinct representatives of the Pteridophyta. These plants had, however, crossed what it has been customary to regard as the boundary between Pteridophytes and Phanerogams: they possessed megasporangia with the attributes of seeds. It has been suggested by Lester Ward[674] that Pteridophytic seed-bearing plants shall be recognised as a distinct phylum for which he proposes the name Pteridospermaphyta, a designation implying exclusion from the Spermatophyta as usually understood. For seed-bearing Lycopodiaceous genera he suggests the name Lepidospermae. As knowledge of the Palaeozoic seed-plants increases revision of existing classifications and group names will become necessary, but as yet we are hardly in a position to draw up a satisfactory scheme of grouping; we know little of _Lepidocarpon_ as a whole and it would be premature to commit ourselves, even provisionally, to a classification which is based on such meagre evidence as we possess. Moreover the value to be attached to the seed-habit as a basis of classification can hardly be estimated until fuller information is obtained. CHAPTER XX. FILICALES. This division of the Pteridophyta includes both the true ferns (Filicineae) and the less familiar water-ferns or Hydropterideae. The almost complete absence of satisfactory evidence in regard to the geological history of the latter renders this group of secondary importance from a palaeobotanical standpoint, but, on the other hand, we possess a wealth of material bearing on the past history and relative antiquity of the true ferns.