222 Yapp . — Two Malayan ‘ My rmecopkilous ’ Ferns . 
formed of only a single valve, and in the curious rootstock.’ 
The indusium, says Mr. Baker, consists of ‘a cup, formed 
from the edge of the frond, holding a small globose sorus.’ 
Christ 1 , however, has pointed out that there is really no 
true indusium. Blume 2 and Mettenius 3 also distinctly refer 
to the sori as being non-indusiate. What has been regarded 
as an indusium is in reality part of the ordinary leaf-lamina, 
which here, as in many other species of Polypodium , forms 
a deep pit, at the bottom of which lies the placenta (compare 
Figs. 39, 40 and 41). Moreover, the inner wall of the sorus- 
cup possesses normal stomata, though these are comparatively 
few in number. This again would suggest that we are simply 
dealing with part of the leaf-lamina. The extraordinary 
rhizome of this Fern being already paralleled in the genus 
Polypodium by those of P. sinuosum and other forms, the 
only reason that remains for retaining Lecanopteris as a 
distinct genus is the curious reflexed position of the sori 4 . 
In all other respects these plants would fall naturally into the 
section Phymatodes 5 of the genus Polypodium. The wisdom 
of maintaining such huge, unwieldy genera as Polypodium 
may perhaps be doubted 6 , but so long as distinct groups 
like Drynaria , &c., are retained merely as sub-genera of 
Polypodium , I think that this is at most the highest rank 
that should be given to Lecanopteris. 
Further, as has been seen, the internal structure of P. car- 
nosum is in many respects very similar to that of P. sinuosum. 
One of the most striking of these resemblances is the posses- 
sion by both species of a specialized water-storing tissue in 
the stem, whose mode of origin, distribution and fate, though 
not in all respects identical, is substantially the same in both. 
These similarities, coupled with the external resemblances 
1 Christ (’98), p. 73. 2 Blume (’27), p. 120. 
3 Mettenius (’56), p. 38. 
4 Some other species of Polypodiwn also have their sori borne on marginal 
lobes, though these are not reflexed as in Lecanopteris , e. g. P. ( Phymatodes ) 
sorridens, Hook.; vide Hooker (’64), p. 60, Tab. 283 B. 
5 As defined by Hooker in the Species Filicum, vol. v, p. 55. 
6 Cf. Fee ( > 50-’52) in the preface to his 7th Memoire, 
