88 vi. roLYsncnuM. 
The Common Prickly Shield Fern has a large tufted 
caudex, which is very enduring, and in age acquires a 
woody character; from it are produced the numerous 
strong coarse roots and the terminal adherent fronds. 
The latter are persistent, retaining their verdure through 
the winter, and their form for three or four years ; the 
young ones grow up about April, and when about half 
developed, their apex is curved backwards in a very 
elegant manner. By mid-summer they have reached 
their full growth. They vary from one to two or three 
feet in height, and are of a lanceolate figure, and tough 
rigid and leathery in texture, so that the fronds droop 
but slightly. The species, however, is not inelegant, the 
rachis often assuming a lateral curve, and the upper sur- 
face of the frond being more or less shining. The stipes 
is short, and densely scaly, the scales being rust-coloured, 
large at the base of the stipes, and becoming smaller up- 
wards. The fronds are bipinnately divided, the pinna; 
being alternate, and pinnate as far as or beyond the 
middle, the pinnules either attached to the midrib in a 
markedly decurrent manner, or else less decurrent and 
with a more stalk-like attachment, when this is not easily 
distinguished from P. angulare. In the most distinctly 
stalked examples I have seen of P. aculeatum, the base 
of the pinnule was, however, decidedly wedge-shaped, 
gradually narrowing from its widest diameter at the 
auricled part, down to its attachment with the rachis, the 
base of the pinnule thus forming an acute angle, the point 
of which touches the rachis ; the attachment of the stalk- 
like base of the pinnule with the rachis also describing an 
acute angle. Both the form of the base of the pinnule, 
and the manner in which it is attached to the rachis, in 
P. angulare differ from this, and present, I think, the best 
means of distinguishing the two plants in their nearly 
allied states. There is no difficulty whatever in dis- 
tinguishing them when the pinnules of P. aculeatum are 
less apparently stalked, for the decurrent pinnules afford 
a certain mark of distinction. The pinna) of P. aculeatum 
are narrow-lanceolate; the pinnules somewhat crescent- 
