172 
The Ferns of South Africa. 
the indusium is somewhat intermediate in character. From 
Nephrolepis the general habit and articulated pinnae of the latter 
furnish a distinction ; while in Oleandra the habit itself is distinc- 
tive. From Polypodium there is the general distinction that the 
latter has no involucre ; but in some Nephrodiums it is fugacious, 
and in others it is generally present but sometimes absent, or 
abortive, and when this is the case they are not distinguishable 
from Polypodium. 
The genus is divided by Hooker and Baker into sub-genera, in 
which our species are distributed as under. 
§ Lastrea. Presl. Veins all free. ioo, ioi, 105, 106, 107, 108, 109, 
no, hi. 
§§ Eu-nephrodium. Lower veinlets of contiguous groups united. 102, 
103, 104. 
§§§ Sagenia. Presl. Veins anastomosing freely, 112. 
There is nothing natural in the above arrangement, and even 
as an artificial arrangement it has been repeatedly broken through, 
as almost every South African botanist has confused N. Bergianum 
with N. molle and N. Mauritianum, and on this account it is not 
used here. 
Synopsis of the species. 
§ Fronds two-pinnatifid. Veins free, or those from neighbouring pinnules 
meeting. 
100. N. albopunctatum. Rhizome long, slender. Sori mostly one to 
each pinnule. Veins free, simple. 
101. N. Bergianum. Rhizome short, with sub-erect crown. Sori 
numerous in the pinnules. Veins free, simple ; texture thin. 
102. N. mauritianum. Pinnules not close ; texture thin. Veins 
simple ; two or more pairs of veinlets from neighbouring pinnae 
meeting. 
103. N. molle. Pinnules close or over-lapping ; texture firmly 
herbaceous. Veins simple ; several lower pairs from neighbouring 
pinnae meeting. 
104. N. unitum. Texture coriaceous, nearly glabrous, several pairs of 
veinlets from neighbouring pinnae meeting. 
