100. FILICES. 519 



* Capsules with an elastic marginal ring. 

 [Suborder I. POLYPODIACEJE. 



Capsules in dorsal or marginal clusters, opening transversely 

 or irregularly. Young fronds circinate. 



"t Clusters dorsal. Ring vertical^ usually incomplete. Caps. 

 opening transversely. 



Tribe I. POLYPODIES. Clusters nearly circular, without 

 an indusium, seated upon the back of the lateral veins. 



1. CRYPTOGRAMME. Clusters circular, at length confluent, 

 concealed by the reflexed margin of the frond. Barren and 

 fertile fronds dissimilar. 



2. POLYPODIUM. Clusters circular, naked ; edge of the frond 

 flat, not reflexed. 



3. WOODSIA. Clusters circular, with an inferior involucre 

 divided at the edges into many capillary segments. 



Tr. IT. ASPIDIE/E. Clusters nearly circular, covered by an 

 indusium, seated upon the back of the lateral veins. 



4. LASTREA. Indusium reniform, attached by the notch. 

 Veins distinct after leaving the midrib, not uniting with 

 those of the adjoining lobe. 



5. POLYSTICHTJM. Indusium circular, attached by the centre. 

 Veins distinct after leaving the midrib. 



6. CYSTOPTERTS. Indusium attached by its broad hooded 

 case under the clusters, with a long fringed free extremity 

 at first covering the capsules. 



Tr. III. ASPLENIE^E. Clusters oblong or linear, usually 

 covered by an indusium opening longitudinally on one side, 

 placed on the side of the lateral veins. 



7. ATHYRIUM. Clusters oblong-reniform. Indusium open- 

 ing towards the central vein or midrib, margin fringed. 



8. ASPLENIUM. Clusters long, straight. Indusium opening 

 towards the central vein or midrib, nearly flat. 



9. PHYLLITIS. Clusters long, straight, 2 together. Indusia 

 of each pair opening towards each other. 



