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Affinities of Peranema and Diacalpe . 
Woodsia and Hypoderris. The texture and insertion of the indusium are 
similar in all the four genera, while they all occupy an undoubtedly inter- 
mediate position between the Cyatheaceae and certain phyla of the 
Polypodiaceae. 
It would seem that the very different habit of Woodsia on the one hand, 
and of Peranema and Diacalpe on the other, can be readily accounted for on 
the ground of environment, while the same remark applies to Hypoderris. 
Hypoderris has probably developed its hardly divided leaf in relation to con- 
ditions of shade. Peranema and Diacalpe, both inhabitants of mountainous 
tropical forest, have grown luxuriantly, while Woodsia , an essentially 
Alpine Fern, has reduced its vegetative system and elaborated the pro- 
tective coverings of its indusium in a series of highly efficient scales. 
Peranema and Diacalpe are undoubtedly very closely related to each 
other. It is hardly possible to say which is the more primitive, which the 
more advanced. The receptacle, sporangial succession, and annulus of 
Peranema are more nearly related to those of the Cyatheaceae than are 
those of Diacalpe. On the other hand, Diacalpe shows an undoubtedly 
Cyatheaceous prothallus. The spore-markings in Diacalpe most closely 
resemble those of Nephrodium filix-mas ; those of Peranema are most nearly 
related to those of Dryopteris pulvinulif era. The presence of hairs on the 
stalks of the sporangia is common to both Diacalpe and Nephrodium filix-mas. 
It would therefore seem probable that Peranema and Diacalpe fall 
naturally into the Woodsieae-Woodsiinae group of Polypodiaceae, and that 
this group occupies an intermediate position between the Cyatheaceae and 
certain other families of Polypodiaceae. There is very little doubt that 
both genera are closely related to the genus N ephr odium. It seems probable, 
then, that the Aspidieae sprang from a Gradate drift, of which the Cyathe- 
aceae are near living representatives, and that Peranema and Diacalpe are 
related to that drift as relatively early examples. These indications make 
it seem probable that the mixed condition of the sorus of Nephrodium has 
arisen from a Gradate condition. This position traces one of the poly- 
phyletic lines of the Polypodiaceae to the Cyatheaceae, and establishes 
a probably parallel series to that shown from Dennstaedtia to Davallia and 
its derivatives. 
Summary. 
1. Peranema cyatheoides , D. Don., has an advanced dictyostele without 
any perforations ; its leaf-trace is inserted on the lower half of the leaf-gap ; 
the pinna-supply is ‘ extramarginal ’ to all but the ultimate pinnae, to which 
it is ‘ marginal ’ ; the sorus, which is borne on a short stalk, is a mixed one ; 
it has a Gradate receptacle, with traces remaining of a basipetal sequence 
of sporangia ; the annulus is slightly oblique ; the spores are ‘aspidioid ’. 
2. Diacalpe aspidioides , Bl., coincides with Peranema in the details 
