520 100. F1LICES. 



10. CETERACH. Lateral veins anastomosing; clusters attached 

 to their middle on the side next the midrib, except in the 

 lowest. Indusium (?) a narrow nearly erect membrane on 

 the back of the vein. Whole back of the frond covered 

 with chaffy scales. 



[11. GYMXOGRAMME. Clusters oblong or linear on both 

 branches of the forked vein, becoming confluent and cover- 

 ing the back of the frond. Indusium wanting.] 



Tr. IV. ADIANTEJE. Capsules covered by a marginal or 

 submarginal elongated part of the frond, or by a separated 

 portion of the cuticle resembling an indusium. 



12. BLECHNUM. Capsules in a continuous line parallel to 

 the midrib upon a longitudinal anastomosing part of the 

 transverse veins, covered by a continuous scarious indu- 

 sium. Barren and fertile fronds dissimilar in our plant. 



13. PTERIS. Capsules in a continuous marginal line covered 

 by a continuous indusium formed of the reftexed margin. 



14. ADIANTUM. Capsules marginal, oblong or roundish, 

 covered by distinct reflexed portions of the margin of the 

 frond. 



ft Capsule opening irregularly, seated on a receptacle which ends 

 a vein at the edge of the frond. Ring oblique, transverse, 

 complete. 



Tr. V. HYMENOPHYLLE&. 



15. TRICHOMANES. Capsules on a long filiform receptacle 

 within a cupshaped involucre of the same texture with the 

 frond. 



16. HYMENOPHYLLUM. Capsules on a narrow subclavate 

 receptacle within a two-valve d involucre of the same texture 

 with the frond. 



** Capsules without an elastic ring, 

 Suborder II. OSMUNDACE^. 



Young frond circinate. Rachis woody. Capsules regularly 

 2-valved, stalked, in clusters at the extremity of the frond. 



