KEY TO THE GENERA. 



Sori near the margins. Indusia 

 formed by the reflexed edges of the 

 pinnules. 



c. Sporangia in a continuous line; 

 fronds large, ternate \ indusium 

 narrow. Bracken, PTERIS. 69 



c. Sporangia in oblong or lunate 

 sori, under a reflexed tooth of the 

 pinnule ; indusium broad ; stipe and 

 rachis dark and shining. Maiden- 

 hair. ADIANTUM. 242 



c Sporangia in roundish masses. 



t Indusium broad, nearly continu- 

 ous ; fronds smooth ; stipes usually 

 dark; rock species. Cliff brakes. 

 PELUEA. 



f Indusium narrower, seldom con- 

 tinuous, often inconspicuous ; 

 fronds usually hairy. 



CHEILANTHES. 



237 



f Indusium of the reflexed edges, 

 at first reaching nearly to the mid- 

 rib, later nearly flat ; fruiting pin- 

 nules, long, podlike ; sterile fronds 

 broad ; stipes pale. Rock brakes. 

 CRYPTOGRAMMA. 



287 



