VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACEJE 237 



from which the cover of the antheridium is formed. The outer 

 wall of the antheridium remains for the most part but one cell 

 thick, in tljis respect more resembling Marattia than it does 

 Botrychium. The antheridium also opens by a single, nearly 

 triangular opercular cell (Fig. 125, E), as it does in Marattia. 

 The spermatozoids were not seen, but probably resemble those 

 of Botrychium or Marattia. 



The first division of the young archegonium is the same as in 



Fig. 126. — A, Longitudinal section of a large prothallium of Botrychium Virginianum, 

 X15; B, transverse section of a somewhat younger one, showing the antheridial 

 ridge, and the archegonia; C, prothallium of Helminthostachys Zeylanica, X7; 

 D, young antheridium of Helminthostachys, X22S. (C, D, after Lang.) 



the antheridium. From the inner cell, after it divides into a 

 basal and a central cell, is formed the axial row of cells — the 

 tgg cell and the canal cells. No division of the neck canal cell 

 was observed beyond the division of the nucleus, and the ventral 

 canal was not seen ; but the latter is doubtless formed before the 

 archegonium is mature. 



The neck of the archegonium remains very short, scarcely 



