Proceedings of the Ohio State Academy of Science. 275- 



12. Vascular bundles 2, often uniting, not incurved; sori on specialized 



lea\'es ; pinnules pinnately veined, barely dicbotomous 



Matlciiccia ( 18 ) . 



12. Vascular bundles strongly incurved, venation distinctly dicbotomous. 



i;i 



\'i. Sporangiopbore distinct, usually on a stalk beside tbe leafblade; 

 sporangia large, globular BotrycJiiuiii (2). 



13. Sporangia on specialized leaflets at tbe end or sides of tbe foliage 



leaves ; or on specialized leaves ; vascular bundle in base of 

 petiole 1 ; leaves 2 or more feet long, bipinnatifid or bi- 

 pinnate Osiiiunda (3). 



14. Sori witb marginal indusia formed by tbe more or less altered and 



rellexed edge of tbe leaflet or its lobes. ]."). 



14. Sori witb special indusia or naked, not covered by tbe margin of tbe 



leaflet. 10. 



15. Only tbe tips of tbe lobes of tbe leaflets reflexed as indusia. 



Idiantnni ( 5). 



15. Entire? margin of tbe leaflets reflexed to form tbe indusium, rarely 



interrupted PcUaca (7 ). 



IG. Sori linear or oblong, indusia more tban twice as long as broad. 17. 



16. Sori round or roundish, indusia less than tw^ice as long as broad. 18 



17. Sori elongated, on the upper sides of the veins Asplcniiim (9). 



17. Sori and indusia somewhat curved, sometimes horseshoe-shaped 



many of tnem crossing tbe veinlet, sometimes with 2 sori placed 

 back to back ; leaves bipinnatifid or bipinnate in our species, usu- 

 ally 2-3 feet long -ithyriuiii (10). 



18. Sori naked, circular; petiole witb 2 miitcd vascular bundles; leaf 



blades triangular or ternate Phcgoptcris ( 14) . 



18. Sori witb indusia. sometimes inferior and obscure; leafblade not 



triangular nor ternate. IH. 



19. Indusium suiierior, cordate or reniform, attached by tbe sinus. 



Dryopteris ( 13) . 



19. Indusium convex, delicate and partly inferior, attached by a broad 

 base at the side and enclosing the sorus like a hood ; leaves 

 sometimes witb brood-buds Filix (15). 



19. Indusium wholly inferior. 20. 



20. Indusium roundish or stellate, delicate, cleft into narrow segments; 



leaves in our species usually not over 16 inches long. Woodsia (16). 



20. Indusium cup-shaped, somewhat 2-valved ; leaves in ours usually 



over 2 feet long Dcnusiacdtia (17). 



