50 HISTORY OF BRITISH FERITS. 
6. Ath 3 rrium = Dorsal-fruited Ferns, having oblong reni- 
form indusia, attached by their concave side, the 
detached side fringed with hair-like segments. 
7. Asplenium = Dorsal-fruited Ferns, having the indusia 
straight and elongate, and attached by the side to- 
wards the margin of the pinnae or pinnules. 
8. Scolopendrium = 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. 
§ LOMAB^IE^ = Ferns whose sori ham special in- 
dusia, forming 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. 
§ PTEHIDEiEi = Ferns the margin of whose fronds is 
soniferous ^ and continuously or interruptedly changed 
