570 PLANTS JAVANIC^ RARIOUES. 



Poll/podium vulgare is one of the best examples of this 

 section, which, however, comprehends species with undi- 

 vided, pinnatifid, pinnate, bipinnate, and even decompound 

 fronds, and these as various in texture as in division. 

 Many species are found within the tropics ; but the 

 section includes all the European Polypodia and most of 

 those found in the higher latitudes of the southern hemi- 

 sphere. 



As this section includes many of the earliest described 

 species of Polypodium, it would require, if retained entire, 

 no subgeneric name. But in a complete analysis of the 

 genus it ought to be divided. The strictly natural sub- 

 divisions, however, can hardly be characterised from 

 modifications of vascular structure alone ; and I have not 

 yet been able to detect sufficient differences, either in the 

 capsules or seeds, by which they may be distinguished. 



That subgeneric or sectional characters may in several 

 instances be obtained or assisted from the seeds of this 

 Natural Order is not improbable, and in one case, namely 

 Ceratopteris (or Teleozoma), including Parkeria in that 

 genus, even the generic character appears chiefly to reside 

 in the seeds, which in their unusual size and pecuhar 

 marking or striation entirely agree in all the species of the 

 genus, while in the original species the annulus is nearly 

 complete ; and in Parkeria, differing from the rest of the 

 genus in no other point whatever, the ring is reduced to a 

 few faint striae. 



Tab. I. Mg. 1. A frond of Polypodium {Dipteris) 

 Horsfieldii, of the natural size. Fig. 2. A portion of the 

 under surface magnified, showing the arrangement of the 

 veins and sori. Fig. 3. Another portion of the same, from 

 which a sorus has been removed to show its insertion. 

 Fig. 4. A sorus, more highly magnified. Fig. 5. A cap- 

 sule before bursting. Fig. 6. A capsule after bursting. 

 Fig. 7. Sporules. 



