96 ON THE CLASSIFICATION OP FERNS. 



f Segments narrow-lanceolate, rather thick, attached to the 

 stalk by a broad base, and confluent. Sori golden-yellow, 



without any indusium POLYPODIUM VULGARB. 



Segments distinct or stalked, ovate-falcate, prickly-toothed, 



14 with a prominent angle or lobe at the base on the inner 

 side. Sori with a small circular indusium. 



ASPIDIUM LONCHITIS. 



Segments small, obovate. Stalk black and slender. Indu- 

 ^ sium attached laterally ASPLENIDM TRICHOMANES. 



( Lower pair of pinnas much larger than the others, giving 

 the frond a broadly triangular or rhomboidal form . . 16' 



15 { Lowest pair, or several lower pairs of pinnas, decreasing in 



size, or not larger than the rest. Frond ovate or lance- 

 i. olate in outline 17 



' Fronds once-pinnate, with pinnatifid segments. 



POLYPODIUM PHEGOPTERIS. 

 Fronds twice-pinnate, the pinnas mostly opposite. 



POLYPODIUM DRYOPTERIS. 

 Fronds twice-pinnate, the pinnas mostly alternate. 



CYSTOPTERIS. 



I Fronds delicate, seldom a foot high, without any brown 

 scarious scales (or very few at the base of the stalk), 

 twice-pinnate, with stalked pinnas 18 



17 -j Fronds stiff, 1 to 3 feet high or more (except in the Beech 



Polypody). The stalk more or less shaggy below the leafy 



part, with brown scarious scales (except in. the Marsh 



{_ Shield Fern) 19 



f Segments with fine-pointed teeth ASPLENIUM. 



I Segments oblong or lanceolate, nearly sessile, with obtuse 



18 { teeth or lobes CYSTOPTERIS. 



Segments small, obovate, stalked, with obtuse teeth. De- 

 licate annual GYMNOGRAMMA. 



Fronds pinnate, the pinnas deeply pinnatifid, the lobes 



16- 



i 1 



19 



entire or obtuse, and slightly toothed 20 



Fronds twice-pinnate, the segments sharply toothed or pin- 

 natifid 24 



i Pinnas (all but the lowest pair) attached to the stalk by 



20 < their broad base POLYPODIUM PHEGOPTERIS. 



( Pinnas attached by their midrib only 21 



( Lobes of the pinnas entire. Sori near their margins. . 22 



21 < Lobes of the sori slightly toothed. Sori near their base or 

 ( centre 23 



