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FILICES. 1033 



{Fronds deeply pinnatifid, with entire segments. Sori linear, concealed 

 by the scales 10. Ceteeach. 

 Fronds twice pinnate, with small segments. Sori circular, with chaffy 

 hairs intermixed 15. Woodsia. 



f Tall, erect, stiff fern, ternately divided, with pinnate branches and ses- 

 sile lobes 12. Pteeis. 



Delicate fern, not a foot high, much divided, with broad, wedge-shaped 

 J- lobes on capillary stalks 13. Adiant. 



{Sori oblong or linear, covered (when young) with a membrane attached 

 along the side 12 

 Sori circular, either without any indusium, or covered (when young) 

 with a membrane attached by the centre or by a lateral point . . 13 

 {Frond entire. Indusium opening in a slit along the centre. 

 9. Haet's-tongue. 

 Frond pinnate or much divided. Indusium opening along the inner 

 side . 8. Spleenwoet. 



f Fronds simply pinnate, with entire or toothed segments or pinnas . . 14 



13 < Fronds pinnate, with pinnatifid primary divisions or pinnas, or twice 



*■ or thrice pinnate * 15 



r Segments narrow lanceolate, rather thick, attached to the stalk by a 

 broad base, and confluent. Sori golden -yellow, without any indu- 

 sium 4 (1). Common Polypody. 



14 <j Segments distinct or stalked, ovate-falcate, prickly -toothed, with a pro- 



minent angle or lobe at the base on the inner side. Sori with a small, 



circular indusium 7 (1). Holly Shieldeeef. 



^Segments small, obovate. Indusium attached laterally. 8. Spleenwoet. 

 rLower pair of pinnas much larger than the others, giving the frond a 



-. ^ j broadly triangular or rhomboidal form . .16 



i Lowest pair, or several lower pairs of pinnas, decreasing in size or not 

 t- larger than the rest. Frond ovate or lanceolate in outline . . .17 

 r Fronds once pinnate, with pinnatifid segments 4 (2). Beech Polypody. 



16 < Fronds twice pinnate, the pinnas mostly opposite 4 (4) . Oak Polypody. 

 I Fronds twice pinnate, the pinnas mostly alternate . 14. Bladdeefeek. 

 f Fronds delicate, seldom a foot high, without any brown scarious scales 



(or very few at the base of the stalk), twice pinnate, with stalked 



17 J pinnas • 18 



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 



L scarious scales (except in the Marsh Shield/em) 19 



f Segments with fine pointed teeth 8. Spleenwoet. 



| Segments oblong or lanceolate, nearly sessile, with obtuse teeth or lobes. 

 18-^ 14. Bladdekeeen. 



j Segments small, obovate, stalked, with obtuse teeth. Delicate annual. 

 I 6. Gymnooeam. 



* In all twice or thrice pinnate leaves or fronds the primary divisions on each 

 side of the main stalk are called pinnas, the ultimate divisions retaining the name of 

 segments. 



VOL. II. 2 s 



