8Z 
(a), Pinne of the sterile frond not 
much broader. than the others; 
scarcely toothed, 
4. P. pellucida, 
(c) Bipinnate.—Lowest pinne at least 
bipinnatifid. ' 
(2) Pinnz cut down nearly to the rachis 
into numerous linear oblong seg- 
ments. 
5. P. quadriaurita. 
(12) Pinnz cut down into several narrow 
linear lobes which widen sudden- 
ly on both sides within a short 
distance of the base. 
6. P. patens. 
(2) Tripartite.—Lowest pinne much 
longer than the others, often nearly equalling 
the central portion of the frond. 
7. P. wallichiana. 
II. Stipes distant on a creeping rhizome, 
indusium double. 
8. P. aquiiina. 
