BRITISH FERNS. 
90 
of the same-shaped portions of a reflexed and altered 
margin of the frond, bearing the capsules upon them. 
11. Cryptogramme. Sori oblong or linear, situated 
towards the apex of the veins, and covered by the invo- 
lucre formed of the broad revolute margin of the frond. 
Fronds dimorphous. 
12. Blechnum. Sori linear, continuous, parallel 
with and near the costa, running transversely, with the 
veins rarely submarginal. Involucre of the same shape. 
B. Capsules opening irregularly , placed on a columnar or filiform 
receptacle , and terminating a vein at the margin of the frond , 
ha, ring a transverse ring , and included in an involucre . Fronds 
delicate , membranaceous . 
13. Trichomanes. Involucre subcylindrical, nearly 
entire. Receptacle usually exserted. 
14. Hymenophyllum. Involucre 2-valved. Recep- 
tacle rarelv exserted. 
9 / 
Suborder 2. Osmundese. — -Capsules clustered at the 
margin of a transformed frond or portion of a frond, 
reticulated, opening by two regular valves; ring 
almost obsolete. Fronds circinate in venation. 
15. OsMUNDA. 
Suborder 3. Ophioglossese.— Capsules globose, between 
coriaceous and fleshy, sessile, forming a simple or 
compound pedunculated spike, distinct from the 
sterile frond, and opening transversely by two equal 
valves. Fronds straight in vernation. 
16. Ophioglossum. Capsules connate, on a 2-ranked 
spike. 
17. Botrychium. Capsules free, arranged on one 
side of a pinnated spike. 
