APRIL. 



105 



The Aspidiece, known by the attachment of the covers of their dot- 

 ' ike sori, comprise twelve genera, one of which, Onoclea, is distinguished 



by its having the fertile 

 fronds contracted, the 

 indusium being not 

 easily made out among 

 the crowded spore-cases. 

 The other genera are : — 

 With peltate indusia — 

 Aspidium and Cyrto- 

 mium, with reticulated 

 veins ; Cyclodium, with 

 connivent veins ; and 

 Polystichum, with the 

 veins free. With reni- 

 form indusia : — Fad- 

 yenia, Sagenia, and 

 Pleocnemia, with reti- 

 culated veins ; Nephro- 

 dium, with the veins 

 connivent ; and Lastrea, Oleandra, and Nephrolepis, with the veins 

 free. 



The Cystopteridece are a small group comprising three genera, the 

 two latter of which have usually been associated with Davalliece. They 

 are separated by having their indusia attached at the base only trans- 

 versely on the vein behind the sorus and inflected over it. The genera 



§19. Aspidie.e: Cyrtomium'falcatum. 



Ctstoptkbide* : Cystopteris tenuis. 



are : — Cystopteris, with medial sori ; Aerophones, with terminal (or 

 sometimes axillary) sori — these two having thin tender fronds ; and 

 Humata, with terminal sori and thick coriaceous fronds. 



The Davalliece are distinguished by having an elongated tubulose 

 indusium, or else, if shorter and roundish in outline, it is adherent by 

 the margin as well as the base.. The genera here placed are : — Micro- 



