E 108 CHARACTERS OF TRIBES AND GENERA. 
A. Fronds uniform, base dilated. 
* Sori numerous, irregular. 
T Fronds simple. 
D. musefolia (BL) (v v.) 
tt Fronds pinnatifid. 
D. Heraclea (Kze.) (v v.) 
** Sori oblique serial. 
t Fronds pinnatifid. 
_D. coronans ( Wail.) (v v). 
B. Fronds dimorphous. 
* Sori oblique, 1 to 2 serial. 
T Fronds pinnatifid. 
D. Fortunei (Kze.) ; D. quercifolia (Linn.) (v v.) 
** Sori transversely uniserial, 
t Fronds pinnatifid. 
D. propinqua (Wall.) (v v.); D. Willdenovii (Bory.) 
tt Fronds pinnate (Poronema.) 
D. diversifolia (R. Br.) (v v.); D. glaucistipes ( Wall.) 
Oxs.—The two last species differ from the rest in having | 
pinnate fronds, and are specially marked by having à ` 
small impressed pore at the base of each pinns, which, ` 
with their pinnate fronds, is sufficient to mark them as a 
distinct group, under the sectional name of Poronema. 
23. Dryosracnyum, J. Sm. (1841). 
x. ` Surculum short and thick. ` Fronds contiguous, sessile, 
2 rigid, l to 3 feet high, pinnatifid, segments articulated: 
_ with the rachis, sterile below, the base dilated, the upper 
segments pinnate, contracted and fertile. Veins of storie 
segments costæform; venules and veinlets compound 
anastomosing, forming nearly equal quadrangular areo o8 
