VIII. ATHYKIUM. 143 
from the delicate texture of the frond. In average 
specimens the mid-vein is waved, the veins being forked 
shortly after leaving it ; the anterior vemile bearing on its 
anterior side the oblong sorus, which is ranged somewhat 
nearer the mid-vein than the margin ; the other venule 
becomes forked or not, according to the exposition of 
the frond, one branch extending to each serrature. In 
the larger and more divided pinnules, where the veins 
branch alternately, and bear more than one sorus, the 
latter appear very irregularly disposed. The sori are 
oblong, sublunate, or elongate-reniform, and they are 
covered by an iudusium of the same form, opening to- 
wards the mid-vein, its free margin split into narrow 
capillary segments. Sir J. E. Smith remarks that the 
sori finally become nearly round, and the indusium orbi- 
cular, with a notch at the base, thus assuming the 
character of an Aspiditim, which view led him to refer 
this plant to that genus ; but these are only instances, of 
frequent occurrence indeed, in which the sorus is con- 
tinued across the vein and returned on the other sido, so 
as to acquire the form of a horseshoe, various degrees of 
which, along with the linear form of sorus, may be found 
in almost every plant of this and the allied species. 
The variety latifolium is a very distinct-looking plant, 
differing at first sight in its narrower and more elongated 
outline, and in the inequality and densely crowded condi- 
tion of the pinnules. The more special differences occur 
in the form and uneven toothing or laciniation of the pin- 
nules, and in the situation of the sori. The fronds are 
three feet or upwards in height, elongate-lanceolate, bi- 
pinnate, flaccid, dark green. The stipes is short, and, iis 
well as the rachis, stout, the lower part of the rachis be- 
ing furnished with a few scattered narrow scales. The 
pinnae are alternate, approximate on the upper part of the 
frond, distant below, about four inches long at the broadest 
part of the frond, linear-lanceolate, tapering to a sharp 
point. The pinnules are ovate, blunt or sometimes acute, 
