( 2 ) 
* * * Marginal. 
Terminating costa or vein, sunk in frond or 
exserted, invol, of same text, as frond, recep- 
tacle elongated. 
Invol. two-lipped, toothed or fringed or entire, re- 
ceptacle columnar. 
(Frond small, delicately membranous). 
1G Hymenophyllum. 
Invol. tubular, with winged or truncated or slightly 
two-lipped mouth : receptacle filiform. 
(Habit similar to last). 17 Trichomanes. 
Intra or submarginal, globose or elongated 
either way. 
Invol. terminal on veins, free at apex. 
(Four types of involucre, and two distinct habits 
of growth. Veins free). IS Davallia. 
Invol. membr. like a hood. 
(Fronds small, text. thin. Veins free). 
19 Cystopteris. 
f f SUBGLOBOSE. 
Dorsal. 
Invol. orbicular , fixed by centre : sori terminal on 
veinlets. 43 Aspidium. 
Invol. reniform attached by sinus. 
Sori dorsal or terminal on veinlets. 
(Species numerous, differing widely in size, cutting, 
and venation). 44 Nephrodium- 
Sori at apex of upper branch of vein, generally 
near edge. 45 N ephrolepis. 
Fronds pinnate, veins free : pinnae articulated at 
base, dotted (cretaceous) white on upper surface. 
Sori in row near base, or below centre of compact, 
free veinlets. 4G Oleandra. 
+ f f Linear. 
At or near elge of frond, at apex of and unit- 
ing two or more veins. 
