IX FILICINEJE LEPTOSPORANGIATAL 311 



folded (Salviniacese) ; sporangia without an annulus and borne 

 in special ''sporocarps," which are either modified branches of 

 ordinary leaves (Marsiliaceae) or a very highly developed 

 mdusinm. 



Order IL Hydropterides. 



Family i. Marsiliaceae. 



Family 2. Salviniacese. 



Order I. Filices 



The eight families of the Filices form an evidently very 

 natural group, but there has been a good deal of disagreement 

 as to their relative positions. The Osmundacese are generally 

 recognised as approaching most nearly the eusporangiate Ferns, 

 and the Gleicheniaceae come next to these. The Hymeno- 

 phyllace?e are usually considered at the other extreme of the 

 series, but there are a number of reasons why this seems doubt- 

 ful, and I am inclined to assign them an intermediate position. 

 Their structure and development give evidences of their being 

 a specially modified group adapted to living in very damp 

 situations, and they probably cannot be regarded as connecting 

 any of the other families, but rather as a side branch which has 

 developed in a direction away from the type. They come near- 

 est the Gleicheniacese and Osmundacese in the structure of the 

 sexual organs, and the sporangium shows points in common 

 with the former family. The sporangium, however, also re- 

 sembles that of the Cyatheace?e, and the strongly-developed in- 

 dusium is much like that of the latter. The Schiz?eacecV^ also 

 may possibly form a side branch from the ascending serief 

 whidi ends in the Polypodiacese. 



Professor Bower (19), w^ho does not recognize the Ophio- 

 glos^acese as belonging to the Filicineae, divides the other hom- 

 osporous Ferns into three suborders, based upon the develop- 

 men, of the sporangia. His first suborder, ''Simplices," includes 

 the Marattiacese, Osmundacese, Schizseacese, Gleicheniaceae, and 

 Matoniacese. In these families all the sporangia in a sorus are 

 developed simultaneously, and the output of spores is rela- 

 tively large. The second suborder, ''Gradatse," comprises the 

 Hynienophyllaceae (inc. Loxsomaceae), Cyatheacese (inc. Dick- 

 sonie?e — in part), and one sub- family, Dennst?edtine?e, belong- 

 ing to the Polypodiacese. In these the sporangia arise in 



