Tris£ 1 — II. Gkx. I— II. 
CHAPTER III 
OF GENERA. 
As we descend from the great divisions of our subject 
to the less, we find much more obvious characteristics by which 
to guide our enquiries. Instead of having, as in the last chapter, 
to turn our attention to the capsules and their annulus we find 
that the generical description is chiefly concerning the shape and 
position of the sorus, the absence or presence and form of the 
involucre and the manner in which the veins are arranged, for 
although other characteristics maybe occasionally mentioned, those 
of fructification and venation are the most important. 
Tribe I. — Gleicheneace^e. 
Gen. I. — Gleichenia. Sorus naked, although in some of the 
species the margin is so curled back as almost to conceal it. The 
ferns of this genus are stiff and leathery in texture ; stipes erect, 
stiff, generally very tall and slender ; the frond branches 
dichotomously, — that is, divides at one point into two which 
branches in their turn divide in like manner, often bend- 
ing gracefully on either side. 4 Species. This genus is divided 
into two sections : 
§ 1. — Eugleichenia. Sorus at the point of a veinlet. Seg- 
ments of the pinnae very narrow and notched. Sp. 1, 2. 
§ 2. — Mertensia. Sorus at the middle or angle of a veinlet. 
Segments of the pinnae with even edges. Sp. 3, 4. 
Tribe II. — CyathejE. 
Gen. II. — Cyathea. Sorus on the back of the frond, removed l 
from the margin, although when very ripe the whole of the back of i 
the frond is sometimes covered by the mass of fructification. In- 
volucre globose, at first closed but when ripe bursting irregularly^ 
8 
