( 37 ) 
GROUP I; GENUS XII. 
POLYSTICHUM. 
Sori. Circular, growing from the upper part of the 
venules. Indusium peltate or mushroom¬ 
shaped, attached to the back of the venule 
by a central stalk. 
Venules. Free. 
GROUP I; GENUS XII; SPECIES I. 
POLYSTICHUM ACULEATUM. (Prickly Shield Fern.) 
Plate XVI. 
Fronds. Lanceolate, bi-pinnate, leathery in texture. 
Pinnae long, narrow, triangular and tapering 
to a point. Pinnules decurrent, the larger 
ones auricled at the base; the first upper 
one always larger than any other on that 
pinna. Margins serrated, and armed with a 
few sharp, stiff spines. The pinnules, ex¬ 
cepting the first upper ones before mentioned, 
set on obliquely to the rachis, which is brown 
and covered with scales. Stipes short and 
densely scaly. 
