f 
i 
74 
as a protective structure, it loses its ecological character, but usually 
maintains to a recognizable extent the characteristic form of the cells; 
in such cases, intercellular spaces are often formed by incurrent folds 
of the walls. In my notes such a structure is mentioned in P, accedcns^ 
P. revolutum, P. Zippelii, P. doJicliopiernm, P. 17Jfl {musae folium?), 
P. incurvatum, P. commutaium (fig. 32), P. Pliymatodes, P, Schneideri, 
P. palmatum, P. angustatum, P. alhido-squamatum^ P. (Selliguea) can- I 
dlforme {^g. 33), P. sinuosum (fig. 34), Lecanopteris (fig. 35), P. Jiera- 
cleurUj Drynaria rigidula, D. quercifolium, Dryostachyum pilosum (fig. 
36), Tliayeria {^g. 37), and Photinopieris. It also occurs in P. subauri- 
culatum; but is wanting in Taenitis and ClieiropJeuria, and in P. angus- ' 
tujUj the type species of Pleopeltis, This is one reason "wh}-, if I were 
raising the subgenera of Polypodium to generic rank, I would keep 
■ 
Selligurn, including Phymatodes^ distinct from PleopeUls. 
