1034 THE FERN FAMILY. 



r Fronds pinnate, the pinnas deeply pinnatifid, the lobes entire, or obtuse 

 19 «j and slightly toothed 20 



L Fronds twice pinnate, the segments sharply toothed or pinnatifid . . 24 



r Pinnas (all but the lowest pair) attached to the stalk by their broad 

 20 < base 4 (2). Beech Polypody. 



I Pinnas attached by their midrib only 21 



o-. J Lobes of the pinnas entire. Sori near their margins 22 



I Lobes of the pinnas slightly toothed. Sori near their base or centre . 23 



{~No scarious scales on the stalk. No glands on the leafy part. 

 7 (3). Marsh Shieldfern. 

 Stalk with brown scarious scales at the base. Minute glands on the 

 under surface of the segments . . . 7 (4). Mountain Shieldfern. 

 r Segments of the pinnas oblong, very numerous, scarcely broader at the 



23 <j base 7 (5). Male Shieldfern. 



LSegments ovate, wedge-shaped at the base . 7 (6). Crested Shieldfern. 

 ("Segments of the pinnas with finely-pointed, almost prickly teeth ; the 



inner lobe or tooth at the base much larger than the rest. 



24 <[ 7 (2). Prickly Shieldfern. 



I Segments of the pinnas with shortly pointed teeth or pinnatifid ; the 



L lobes of each side similar 25 



f Sori circular. No indusium 4 (3). Alpine Polypody. 



| Sori circular, with a kidney- shaped or almost peltate indusium attached 



25 \ by a point 26 



I Sori rather oblong, with an indusium attached along one side. 



L 8. Spleenwort. 



r Segments ovate or ovate-lanceolate. Indusia conspicuous and persistent. 



26 \ 7(6). Crested Shieldfern. 

 I Segments oblong-lanceolate 27 



o,_ J Indusia conspicuous and persistent. . . . 7(8). Rigid Shieldfern. 

 I Indusia small and often soon disappearing . 7 (7). Broad Shieldfern. 



I. ADDERS-TONGUE. OPHIOGLOSSUM. 



Stem simple, bearing a single leaf in the lower part, and a simple 

 terminal fruiting spike. Spore-cases rather large, closely sessile, in 

 two opposite rows, each opening by a transverse fissure. 



A genus of very few species, but widely distributed over most parts 

 of the globe. 



1. Common Adder's-tongue. Ophioglossum vulgatum, 

 Linn. (Fig. 1258.) 



(Eng. Bot. t. 108.) 



Rootstock very small, but apparently perennial. Frond or stem 

 solitary, from a few inches to near a foot high, with an ovate or oblong 

 entire leaf, usually 2 to 3 inches long, narrowed at the base into 



