900 



Teibe it. CYATHEAGEm. 



Elastic ring usually oblique, and completely surrounding the sporangium ; 

 sporangium often compressed, sessile, or shortly' pedicelled, not continuous with 

 the ring. 



PEINCIPAL GENERA. 



Heaiitelia. Matonia. Alsophila. Cyathea. 



Tkibb III. EYMENOPHYLLEM. 



Elastic ring nearly as in Oyatheaceoe, but the sporangia are nearly globose, and 

 the elastic ring is situated on a plane nearly perpendicular to the point of attach- 

 ment of the sporangium. 



PRINCIPAL GENERA. 



Hymenophyllum. TriohDmanes. Loxsoma. 



TuiBE IV. GEBATOPTEBIBEM. 



Elastic ring Targe, formed of vertical cells, not completely surrounding the 

 sporangium, -which is sessile. 



GENERA. 



Oeratopteris. Parkeria. 



Tkibe V. GLEIGEENIEM. 



Sporangia solitary or grouped in definite numbers (2-3), sessile, globose ; 

 elastic ring perfect, but not corresponding to the point of attachment of the 

 sporangium. 



Gleichenia. 



PRINCIPAL GENERA. 



Mertensia. Platysoma. 



Tribe VI. LYGOBIE^. 



Sporangia sessile, OToid or turbinate ; elastic ring replaced by a sort of cap 



with radiating striae, occupying the end of the sporangium, opposite to the point of 



attachment. 



PRINCIPAL GENERA. 



Aneimia. Schizma. Lygodium. Mohria. 



