540 FILICES. 
sists of a series of cells with thickened and darker walls. Leaves without 
stipular appendages. The sporangia originate from a single epidermoidal 
cell. 
sporangia pedicellate or one i pigs or more generally collected 
into clusters or lines called sori, and these either naked or covered until 
maturity by an involucre or Sotelo forte leaves similar to the sterile 
leaves or changed, smaller or ear ans Main stem usually perennial, 
either an erect or prostrate simple c¢ 2, or reduced to a creeping 
rhizome. Leaves spiral on the erect, sae on the creeping stem; the 
stalk — called a stipes — and often the rhachis carrying scales or hairs, 
which are most numerous at the is of the stipes and the end of the 
stem. 
Trine 1. SCHIZAEEAE. — Sporangia ovoid, crowned at the apex by 
a complete = epeeminder ring, opening vertically, sessile, not collected into 
sori. Gen. 
TRIBE 2. Seaneuee — Sporangia with a complete transverse 
ring, opening vertically, sessile. Sori of few sporangia on the back of the 
frond, naked. Frond rigid, dichotomous, generally with a bud between 
the fork branches. Gen. 3. 
Tre 3. C . — Sporangia with a complete ob ique ring, 
opening transversely. ender erect, generally arborescent. Gen. 4. 
Trise 4. POLYPODIEAE. neat ae ser an incomplete vertical ring, 
opening transversely, pedicellate. 
RIBE5. HYMENOPHYL aes gees orbicular, depressed, with 
a complete transverse or oblique ring, opening bohm sessile on the 
free exserted prolongation of a vein pe eeieongy forming a marginal sorus 
which is included within a tubular, urceolate or bilebinte involucre, the 
involucre supported by two lateral abit ts of the columella. 
ferns, often moss-like, the frond generally consisting of a single layer of 
cells without stomata. Gen. 23—24. 
Tina Afetel tant 
f the veins or nerves in the nie is manifold, but always nee m i 
species and often in a genus. According as they run free from each other sent 
course or unite, according to the presence or absence of a midrib, the angle Mw hen 
they leave the latter, and the combinations of anastomosis when they unite, a 
of divisions haye been established by pteridologists which cannot be ae i 
pecies. 
e general character or habitus of a frond is in a great measure determined by the 
order in which the secondary nerves, segments or pinnules leave the primary segme ent 
or ni a pinna is called ana en the first nerve, o 
pinnule leaves it on the upper side, is turned to f nd and stands neare 
to first nerve, innule of the under side; catadromus 
when the first nerve, segment or pinnule yi os on the riage side, is turned toward 
e base; and homodromous when the first n segments or pinnules of both sides 
stand opposite to wes her. 
In the anadromou ] 
relative order as the sosip t or basal ones, so that the fourth, fifth, fees of the upper side aes 
stand nearer to the rhachis than the corresponding ones of the under side. In the cata- 
