The pyriform and pedicellate sporangia are borne in groups of two to six on the ultimate divisions of the frond; the wall is composed of two layers of cells and on one side of the sporangium is an annulus several cells in breadth (fig. 319, D, F). An interesting type of sporangium described by Oliver[1121] from Grand’Croix in France may, as he suggests, belong to _Botryopteris forensis_; the differences between Renault’s and Oliver’s specimens being the result of the more perfect preservation of the tissues in the latter. The sporangium described by the English author is circular in section and measures 0·65 × 0·53 mm.; the wall is in part composed of a single layer of cells and in part of two to three layers, a character recalling the “annulate” sporangia of _Botryopteris_. Between the spore-mass and the wall is an interrupted ring of short tracheal elements similar to the xylem-mantle which occurs at the periphery of the nucellus of certain Palaeozoic gymnospermous seeds. In the absence of proof of a connexion between this sporangium and _Botryopteris_ it is convenient to use the generic name _Tracheotheca_ subsequently proposed by Oliver[1122]. In the recent ferns _Helminthostachys_ and _Botrychium_, and, as Oliver notices, in the microsporangia of the Australian Cycad _Bowenia spectabilis_, vascular strands extend almost to the sporogenous tissue, but the fossil sporangium is unique in having a tracheal layer in immediate contact with the spores. These xylem elements may, as Oliver suggests, have served the purpose of conveying water to the ripening spores. _Botryopteris hirsuta_ (Will.)[1123]. This English species has a slender axis bearing numerous leaves with petioles equal in diameter to the stem. The surface of the vegetative organs bears large multicellular hairs. The leaf-traces resemble those of _B. forensis_, but the projecting teeth which terminate in protoxylem elements are less prominent than in the French species; the petioles were named by Felix _Rachiopteris tridentata_[1124]. As a leaf-trace passes into the stele of the stem the three protoxylem strands unite and take up an internal position in the solid stele. The stele may, therefore, be described as endarch. The small tracheae at the edge of the stele supply the xylem strands of adventitious roots. Sporangia similar to those of _B. forensis_ have been found in association with the English species. _Botryopteris cylindrica_ (Will.). Fig. 305.