INDEX TO THE GENERA. 



* # * To find the Fern desired, it is simply necessary to 

 look to its fructification, and then, by casting the eye down 

 the following list, the genus to which it belongs will at once 

 be seen ; and afterwards the individual species, name, &c. by 

 referring to the descriptions given under that genus. 



NON-INDUSIATE, 



OR WITHOUT ANY DISTINCT INDUSIUM 

 BELONGING THERETO. 



Sori on the back in lines ; back scaly. 

 GRAMMITIS. 



Sori on the back in round masses, perfectly 

 naked. 



POLYPODIUM. 



Sori circular, beneath the recurved margin of 

 the pinnule. 



CRYPTOGRAMMA. 



