CHARACTERS OF TRIBES AND GENERA. E 1x 
terminal, lateral or compital, punctiform, oblong, or by 
confluence linear naked. 
Oss.—This tribe consists of about 200 described species. 
The greater number come under the genus Polypodium, as 
characterised by early authors, that is in having puncti- 
form naked sori. The greater mass of the species have 
anastomose venation, from simply reticulated to compound, 
with free veinlets terminating in the areoles. In many 
cases this difference alone is not sufficient to define natural 
genera; to do so it is necessary to make habit and any other 
special structure of the fronds an important character in 
arranging the species into natural groups, which, on 
account of the gradual transition, it in many cases becomes 
difficult to determine the group in which the transition ` — 
Species should be placed. Authors are much divided on — 
this point, for instance, the venation of Phymatodes as 
characterised by Presl, I in 1841, considered it did not 
differ from the earlier founded genus Drynaria of Bory, 
while Moore, in his “Index Filicum,” places the whole of 
_ Presl’s Phymatodes, with the exception of the section Dry- 
naria, under the early named genus Pleopeltis, also in- 
cluding under it the whole or a portion of the species of no 
less than twenty-four genera of different authors. Of : 
Drynaria of Bory he says, “We have kept separate the 
am very distinct-looking little groups of Drynaria and Dipteris, — 
the former distinguished by its peculiar sessile, sterile - 
fronds, the latter by its peculiar dichotomo-palmatafid p 
_ fronds, rather perhaps than by differences of higher value.” — 
. After having carefully considered the different views of — 
_ authors, and having had examples before me of the greater - 
number of known species, I have been led to arrange the - 
one eae as follows :— n 
