50 HISTORY OF BRITISH TERNS. 



6. Athyrium = Dorsal-fruited Ferns, having oblong reni- 



forra indusia, attached by their concave side, the 

 detached side fringed with hair-like setrmcnts. 



7. Aspleniiini = Dorsal-fruited Ferns, having the indusia 



straight and elongate, and attached by the side to- 

 wards the margin of the pinnae or pinnules. 



8. Scolopendrinm = Dorsal-fruited Ferns, having the sori 



elongate, and proximate in parallel pairs, the indusia 

 opening along the centre of the twin sori. 



9. Ceterach = Dorsal-fruited Ferns, having the indusia 



obsolete, and the sori hidden among densely imbri- 

 cated, rust-coloured, chaffy scales. 



§ LOMARIE-S] = Ferns whose sort have special in- 

 dusia , fornihuj longitudinal lines between the midrib 

 and margins of the leaflets or divisions of the frond. 

 It contains the genus Blechnum. 



10. Blechnum = Dorsal-fruited Ferns, having the spore- 



cases in a continuous line between the midrib and 

 margin of the divisions of the frond, covered by 

 linear indusia. 



§ PTERIDE^ = Ferns the margin of tchose fronds is 

 soriferous, and continuously or interruptedly changed 



