XVIIl] 



STAUROPTERIS 



31 



oldJiamia, Etapteris Lacattei, and Corynepteris. In all of these the position 

 of the sporangia was either terminal, or marginal. Their structure was 

 massive, the wall relatively thick, and the spore-output from each was high, 

 while the opening mechanism was either rudimentary or primitive. In some 

 of them a vascular strand traversed the pedicel to a point closely below the 

 spore-sac itself. These features all indicate a relation to certain living 

 Eusporangiate Ferns : and it is with them that these plants are to be 

 ranked both on the basis of their vegetative and of their propagative organs. 

 On the other hand comparison may be made with the fossils of the 

 Rhynie Chert. 



Fig. 332. Statiropteris oldhamia Binney. A = sporangium in nearly median section, 

 attached terminally to an ultimate branchlet of the rachis: j/'=stomium. Scott. Coll. 

 2213. ^ = sporangium in tangential section attached to a short piece of the branchlet. 

 Scott. Coll. 2207. C^sporangium with wall burst, attached as before: / = palisade 

 tissue of branchlet. Scott. Coll. 2219. (All figures x about 50.) (From sketches by 

 Mrs D. H. Scott.) (Specimens are from Shore, Littleborough, Lanes.) 



The sporangia of Stauropteris are isolated on the ends of ultimate 

 branchlets which show the anatomical characters of the plant (Fig. 332). 

 Each is approximately spherical, being about 07 mm. in diameter. The 

 sporangial wall is composed of several layers of cells of which the outermost 

 has its cells enlarged and strengthened. There is no specialised annulus, but 

 a well-marked stomium appears at the distal end. A thin cylindrical 

 vascular strand traverses the stalk. The sporangia appear to vary in size, 

 but in a large sporangium about 150 tetrahedral spores appear in a single 

 vertical section, which indicates a spore-output of 1000 or more. The spores 



