266 TAKEDA—ASIATIC POLYPODIUMS. 
the known species have been either reduced as varieties or 
entirely suppressed. On the other hand, a few species which — 
have long been regarded as synonyms have been revived. 
As to the classification, there have been put forward divergent 
views by different pteridologists. In recent years there seems 
to be a tendency to hold a wider view than was the case forty or 
fifty years ago. While Hooker and Baker regard Pleopeltis as a 
synonym of Phymatodes and consider it as a section of the 
genus Polypodium, Beddome retains it as a distinct genus. In 
the more recent classifications, such as of Diels and of Christensen, 
it is also treated as a subgenus of Polypodium ; and this appears 
to be in accordance with the modern conceptions of systematic 
botany. As to the subdivision of Pleopeltis, Diels’ system is 
apparently very convenient. However, if the actual plants are 
studied, his system at once proves to be exceedingly unnatural. 
Thus if such a species as Polypodium hastatum is considered, 
one and the same species would fall into two distinct sections, 
or again if it is placed in his § Pinnatifidae, it would still 
be widely separated from the closely allied P. Englert or P. 
Grifithianum. Moore’s system seems to me far better in this 
respect. Yet, as he laid too much stress on the venation, 
P. rhynchophyllum and P. Griffithianum have been placed in 
§ Phymatodes instead of § Phiebodiopsis. J. Smith has amended 
this defect in establishing a genus Phymatopsis, but his separating 
certain allied species under the generic names of Anapeltis and 
Lopholepis does not seem to be justifiable. Christ mentions 
in his Farnkraéuter a few species of this group. He, however, 
places them under the subgenus Craspedaria, which he char- 
acterises by the dimorphic fronds and by the nervation between 
Goniophlebium and Pleopeltis. The study of the nervation of 
ferns is very interesting and necessary. However, one has to 
be cautious not to be carried away too far by the notion that the 
nervation is of fundamental importance and the only way 
of classification. As a matter of fact, the nervation is liable 
to variation even within one species. P. rhynchophyllum 
would furnish a good example of modification of the venation 
from a comparatively simple and regular type to a more irregular 
and in some degree more complicated. In this way the type 
of the venation found in this species passes to that of another 
species and is finally connected, through several species, with 
the much more compound, different-looking venation of P. 
venosum. If, however, actual plants are examined, it would 
be quite clear how P. rhynchophylium, P. accedens, P. lyco- 
podioides, P. salicifoliwm, P. drymoglossoides, P. soridens, P. 
oodes, P. simplicissimum, P. pilosellum, P. squamulosum, P. 
_ vacciniifolium, P. stenophyllum, etc., are closely allied to each 
