FILICES. 107 



widely ascending, 7 — :8-lobed pinnae, are var. Biscayniamcui 

 D. C. Eaton. Florida. 



19. A. cicutarium Swz. Stipes tufted, 4' — S' long, green- 

 ish, naked; fronds 6' — 15' long, 4' — 6' broad, with 10—15 hori- 

 zontal pinnae on each side, the lower ones 2' — 3' long, i' broad, 

 cut down to the rachis into linear or oblong segments, which 

 are once or twice cleft at the apex; rachis compressed and 

 often winged ; sori principally in two rows. Florida. 



§2. Athyrium Roth. Veins free ; sori more or less cm-ved, 

 sometimes horsesJioe-shaped, often crossing to the outer or lower 

 side of the fruititig veinlet. 



20. A. thelypteroides Michx. Stipes long, erect, stra- 

 mineous; fronds 1° — 2° long, 6' — 12' broad, bipinnatitid ; pinnae 

 linear-lanceolate ; segments crowded, oblong, minutely toothed ; 

 sori 5 — 6 pairs to each segment, slightly curved, the lower ones 

 often double. New England to Kentucky and Illinois. 



21. A. filix-foemina (L.) Bernh. (Lady-fern.) Stipes 

 tufted, 6' — 12' long, stramineous or brownish; fronds delicate, 

 i^° — 3° long, broadly oblong-ovate, bipinnate ; pinnae 4' — 8' long, 

 lanceolate; pinnules oblong-lanceolate, pointed, more or less 

 pinnately incised or serrate, distinct or confluent on the second- 

 ary rachises by a verv narrow and inconspicuous margin ; sori 

 short; indusium straight or variously curved. Small starved 

 specimens growing in mountainous places form the var. exile 

 D. C. Eaton, often fruiting when 3' — 6' high. Narrow forms 

 witli the pinnoe obliquely ascending are var. Michaiixii Mett. 

 {T.>ar. angustitm D. C. Eaton), and other forms equally unim- 

 portant, form the remaining sixty-three varieties that have been 

 described of this species. {Aspidittin filix-fceniina Swz., Nephro- 

 dium asplenoides Michx.) Eastern United States to Utah, Ne- 

 vada, California, and Arizona. 



XVII. SCOLOPENDRIUM Sm. Hart's-tongue. 



Sori linear, elongate, almost at right angles to the midvein, 

 contiguous by twos, one on the upper side of one veinlet, and 

 the next on the lower side of the next superior veinlet, thus 

 appearing to have a double indusium o[)ening along the middle. 

 Name from Gr. uk >\onev^ija, a centipede, alluding to the posi- 

 tion of the sori. Includes five species. 



