108 CHARACTERS OF TRIBES AND GENERA. 



A. Fronds uniform, base dilated. 



* Sori numerous, irregular. 



f Fronds simple. 

 D. museefolia (PL) (v v.) 



ft Fronds pinnatifid. 

 D. Heraclea (Kze.) (v v.) 



** Sori oblique serial. 

 f Fronds pinnatifid. 

 D. coronans (Wall.) (v v). 



B. Fronds dimorpJious. 



* Sori oblique, I to 2 serial. 



f Fronds pinnatifid. 



D. Fortune! (Kze.) ; D. quercifolia (Linn.) (v v.) 

 ** Sori transversely uniserial. 



f Fronds pinnatifid. 

 D. propinqua (Wall.) (v v.) ; D. Willdenovii (Bory.) 



ft Fronds pinnate (Poronema.) 

 D. diversifolia (R. Br.) (v v.) ; D. g-laucistipes (Wall.) 



OBS. The two last species differ from the rest in having 

 pinnate fronds, and are specially marked by having a 

 small impressed pore at the base of each pinnee, which, 

 with their pinnate fronds, is sufficient to mark them as a 

 distinct group, under the sectional name of Poronema. 



23. DRYOSTACHYUM, J. Sm. (1841). 



Surculum short and thick. Fronds contiguous, sessile, 

 rigid, 1 to 3 feet high, pinnatifid, segments articulated 

 with the rachis, sterile below, the base dilated, the upper 

 segments pinnate, contracted and fertile. Veins of sterile 

 segments costseform ; venules and veinlets compound 

 anastomosing, forming nearly equal quadrangular areoles. 



