FERNS OF GREAT BRITAIN. 17 



11. Ceterach. — Clusters of capsules at the back 

 of the frond, placed on netted veins, and lying among 

 thick masses of dark brown chaffy scales, which cover 

 the whole back of the frond ; indusium obsolete. Name 

 supposed to be the Chetherak of the Arabian phy- 

 sicians. 



12. Blechntjm (Hard Fern). — Fructification at the 

 back of the frond, in two narrow lines, one on each side 

 the mid-rib, and covered each by a continuous indusium. 

 Name from the Greek, hlechnon, a name for a fern. 



13. Pteris (Brake). — Fructification seated at the 

 back of the frond, or rather in a line at its margin ; the 

 indusium formed of the reflexed edge of the frond, 

 which dilates into a membrane. Name in Greek, pteris, 

 a fern, from pteron, a plume or feather. 



14. Adiantum (Maiden Hair). — Fructification at the 

 back of the frond, in roundish or oblong clusters, 

 covered by distinct portions of the reflexed membrane- 

 like margin of the frond, opening towards the mid-rib. 

 Name in Greek denoting unwetted, from the peculiar 

 tendency of the fronds to throw off water. 



* * Capmles opening irregularly, having a horizontal or 

 oblique ring, and enclosed in a 1-valved, membrane- 

 like involucre, terminating a vein at the margin of the 

 frond. 



15. Trichomanes (Bristle Pern). — Fructification on 

 the margins of the frond, the clusters having a cup- 

 shaped indusium or involucre of the same texture as the 

 frond, and terminating a vein. Name from the Greek, sig- 

 nifying hair and excess, from its bristle-like receptacles. 



D 



