CRYPTOGAMIA. FILICES. Polypodium. 991 
prevalence of a general resemblance in habit, partly to the different 
appearances observable in them at different ages, or to deficiencies in the 
specific characters. Nor have authors always been scrupulously accu¬ 
rate in the application of the terms used in describing the leaves. 
The plants should not be gathered for examination until of sufficient age 
to attain a full state of fructification. The terms employed in the subdi¬ 
visions of the species, and in characterizing the individuals, should be 
precisely understood. The attention should be more particularly directed 
to the lower parts of the leaves, wings, &c. for there it is that the cha¬ 
racters are most constant, and most observable, the extreme parts gene¬ 
rally running together so as to baffle every attempt at definition. 
The following tabular view of the different British species is offered as a 
mean of facilitating their investigation; the student, therefore, is 
advised first to compare the plant in question with these characters, and 
then to look forward to the descriptions given more at large.* 
(1) Leaves wing-cleft. 
P. vulga're. Lobes oblong, somewhat serrated, blunt. 
(2) Leaves winged. 
P. Lonchi'tis. Wings crescent-shaped, finely and sharply serrated: 
stems with chaff-like scales. 
P. Ilven'se. Wings opposite, triangular, blunt, hairy underneath, very 
entire at the base. 
P. arvdnicum. Wings spear-shaped, wing-cleft, hairy underneath: 
stems hairy. 
P. Phegop teris. Wings strap-spear-shaped, wing-cleft, united at the 
base, hairy underneath. 
P. Oreofiteris. Wings strap-spear-shaped, wing-cleft: lobes bluntish : 
clusters of capsules at the edges. 
(3) Leaves winged; wings deeply wing-cleft. 
P. Filix-mas. Wing strap-spear-shaped: lobes blunt, finely serrated: 
stem chaffy. 
P. Thelyp'teris . Wings spear-shaped, acute: lobes very entire. 
(P. crista'turn. Frond pinnate: leaflets pinnatifid, acute : lobes ovate, 
blunt, crenate, sharply toothed: stalk scaly at the base. E.) 
P. dentdtum. Wings egg-spear-shaped, opposite: lobes egg-shaped, 
blunt, sparingly cut at the sides, finely toothed at the end. 
P. fonta'num. Wings egg-spear-shaped, alternate: lobes deeply scol¬ 
loped. 
* (Some authors have recently divided this genus; including in Polypodium such as 
have no lid or cover to the capsule: Aspidium, cover nearly orbicular, fixed by the centre, 
separating all round : and Cy.\tea , cover orbicular, concave, fixed by a lateral point under¬ 
neath, finally reflexed and jagged; as will be further illustrated by the synonymes. E.) 
VOL, in. 3 D 
