108 ENGLISH BOTAXY. 



Tribe IV.— ASPLENIE^. 



Caudex not growing in advance of the fronds. Stipes not arti- 

 culated to the caudex, and not separating from it. Sori oblong or 

 linear, straight or curved, attached to the side of the veins, which are 

 oblique to the midrib and margin of the frond or segment, generally 

 furnished with an indusium attached longitudinally to the veins: 

 rarely the indusium is absent. 



GENUS XIL—A THYRIUM. Both. 



Fronds produced from the apex of the caudex, usually approxi- 

 mated or tufted, rarely solitary, membranous, decompound. Stipes 

 not articulated to the caudex, containing 2 vascular bundles which 

 unite upwards, giving a horseshoe-shaped section towards the back 

 of the stipes. Veins simple or forked, free. Scales composed of 

 elongate cells, with their boundaries not thickened and uniform in 

 colour with the rest of the cell. Sori oblong, rarely round, often 

 curved or even horseshoe-shaped, attached along the side of the 

 veins. Indusium attached to the vein of and the same shape as the 

 sorus, sometimes crossing the vein and part of it attached to each side, 

 sometimes rudimentary and fugacious or even absent. 



Name from a without, and dvpeos (thureos), a shield, from not 

 having a shield-shaped indusium. 



In a natural arrangement of Ferns, Athyrium would occupy a place 

 between Phegopteris and Lastrea ; it has no affinity with Asplenium 

 or any of the allied genera. 



SPECIES I.— ATHYRIUM FILIX-FCEMINA. Both. 



No. 1869. 



Rabenh. Crypt. Vase. Europ. Exsicc. No. 24. 



Asplenium Filix-fcemina, Bernh. Book. fil. Stud. Fl. ed. ii. p. 493. Hook. & Baker, 



Syn. Fil. ed. ii. p. 227. Koch, Syn. Fl. Germ, et Helv. ed. ii. p. 9S1. Fries, Summ. 



Veg. Scand. p. 82. Gren. & Godr. FL de Fr. Yol. III. p. 635. 

 Aspidium Filix-fcemina, Sicartz. Sm. Engl. Bot. ed. i. No. 1459; and Engl. Fl. 



Vol. IV. p. 295. 

 Polypodium Filix-foemina, Linn. Sp. PI. 1551. 



Caudex stout, erect or oblique, closely covered with the bases of 

 former fronds, dividing early into numerous divisions or crowns, 

 which remain closely packed together. Fronds several from each 



