CHARACTERS OF TRIBES AND GENERA. 205 



falcatum (Sw.) (v v.) ; C. caryotideum (Wall.) (v v.) ; C. 

 Fortune!, /. Sm. (v v.) (Ferns, Brit, and For.) C. Jug- 

 landifolium, Kunze (v v.) (Arriblia, Pr.) ; C. nobile, Kunze 

 (Phaneroplilebia, Pr.) 



OBS. The three first species are natives of India and 

 Japan, the two latter of Mexico and Venezuela. 



Although I have not seen specimens of the Fern 

 described in the " Species Filicum" under the name of 

 Polypodium (CyrtomipTilebium) dubium, a native of Peru 

 and Ecuador, I nevertheless believe it to be a species of 

 Cyrtomium ; and the reason for Sir William Hooker 

 placing it in Polypodium seems to me to be consequent 

 on the sori having through age or otherwise lost the 

 indusium. 



107. PLEOCNEMIA, Presl (1836). 

 Nephrodium Hook. Sp. Fil. ; Polypodium, Gaud. 



Vernation fasciculate, erect, arboroid (vide Cuming). 

 Fronds bi-tripinnatifid, 12 to 15 feet long ; primary pinna? 

 1 to 2 feet long; ultimate pinna? uniformly pinnatifid. 

 Veins of lacinse costaeform ; venules forked, the lower ones 

 arcuately and angularly anastomosing, forming unequal 

 areoles next the costa ; the exterior ones free. Fertile 

 pinnules much narrower than the sterile. Sporangiferoibs 

 receptacles medial on the free or anastomosing venules. 

 Sori punctiform in a row on each side of the costeeform 

 veins of the lacinse. Indusium reniform. 



Type. Polypodium Leuzeanum, Gaud. 



Illust. Hook, and Bauer, t. 97 ; Moore Ind. Fil., p. 70, A ; 

 J. Sm. Ferns, Brit, and For., fig. 71. 



OBS. This genus is founded on a single species, and 

 owes its generic importance more to its gigantic habit 

 than to any real structural difference by which to dis- 



