ix FILICINE1E LEPTOSPORANGIATJE 311 



folded (Salviniaceae) ; sporangia without an annulus and borne 

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

 ordinary leaves (Marsiliaceae) or a very highly developed 

 indusium. 



Order II. Hydropterides. 



Family i. Marsiliaceae. 



Family 2. Salviniaceae. 



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 Osmundaceae are generally 

 recognised as approaching most nearly the eusporangiate Ferns, 

 and the Gleicheniaceae come next to these. The Hymeno- 

 phyllaceae 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 Gleicheniaceae and Osmundaceae 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 Cyatheaceae, and the strongly-developed in- 

 dusium is much like that of the latter. The Schizaeacese also 

 may possibly form a side branch from the ascending series 

 which ends in the Polypodiaceae. 



Professor Bower (19), who does not recognize the Ophio- 

 glossaceae as belonging to the Filicineae, divides the other hom- 

 osporous Ferns into three suborders, based upon the develop- 

 ment of the sporangia. His first suborder, "Simplices," includes 

 the Marattiaceae, Osmundaceae, Schizaeaceae, Gleicheniaceae, and 

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

 developed simultaneously, and the output of spores is rela- 

 tively large. The second suborder, "Gradatae," comprises the 

 Hymenophyllaceae (inc. Loxsomaceae), Cyatheaceae (inc. Dick- 

 sonieae in part), and one sub- family, Dennstaedtineae, belong- 

 ing to the Polypodiaceae. In these the sporangia arise in 



