8o OUR NATIVE FERNS AND THEIR ALLIES. 



10. Sporangia at the ends of the veins, home on a reflexed portion of the 



margin of the leaf ... X. Adiantum, p. 89 



Sporangia borne on a continuous, marginal, vein-like receptacle con- 

 necting the apices of the veins II 



Sporangia at or near the ends of unconnected veins, borne on the under 

 surface of the leaf 12 



11. With an inner indusium inside the receptacle . XII. Pteridium, p. 91 

 With no inner indusium ; our species pinnate . . XI. Pteris, p. 90 



12. Fronds conspicuously dimorphous ; stipes light-colored. 



XIV. Cryptogramma, p. 97 

 Fronds nearly uniform ; stipes usually darkK:olored ... . . 13 



13. Sori on the upper part of the veins, mostly forming a continuous mar- 



ginal band ; indusium membranous, continuous round the segment. 



XV. PELLiEA, p. 97 



Sori minute, at the ends of the veins ; indusium interrupted, or if con- 

 tinuous, the ultimate segments usually small and bead-like ; leaves 

 mostly chaffy, woolly, or farinose, . . , XIII. Cheilanthes, p. 91 



14. .Si5ri roundish ; indusia not more than twice as long as broad ... 15 

 'Sori linear or oblong ; indusia more than twice as long as broad . . 21 



15. Indusium superior, attached by the centre or sinus 16 



Indusium convex, fixed by a broad base partly under the sorus, 



XXVIII. FiLix, p. 119 

 Indusium inferior 19 



16. Sori mostly on the back of the veins .... .... . . 17 



Sori at the end of a free vein ; indusium reniform, opening toward 



the margin of the leaf, which is simply pinnate, the pinuEe articulated 

 to the rachis . . . . .~" . . XXVII. Nephrolepis, p. 118 



17. Indusia centrally peltate . . 18 



Indusia cordate or reriiform, attached by the sinus. 



XXIII. Dryopteris, p. no 



18. Veins free, i — 2-forked XXIV. Polystichum, p. 115 



Veins 3 — s-forked, often uniting in irregular areolae ; leaf pinnate. 



XXV. Phanerophlebia, p. 117 

 Veins copiously anastomosing ; leaf trifoliate. XXVI. Tectaria, p. 118 



19. Indusium roundish or stellate, delicate . . . XXXI. WooDSiA, p. 120 

 Indusium cup-shaped, somewhat two-valved. 



XXXII, Dennst^dtia, p, 122 



20. Leave? growing in crowns ; veins free . . XXX, Matteuccia, p. 120 

 Leaves scattered ; veins copiously anastomosing. 



XXIX. Okoclea, p. 120 



21 . Sori all parallel to the midribs or rachises 22 



Sori all oblique to the midribs 24 



