98 CHARACTERS OF TRIBES AND GENERA, 
further reduced. Presl, however, not only maintains the 
highest number of specie but goes the length of creating 
no less than six additional genera. It is true that their 
venation and position of the sori is variable, but in all 
cases it is simple modifications of compound anastomosing, — 
which is principally due to the more or less contracted ` 
state of the fronds, and which has led Presl to place the 
same species under different genera. The only very 
evident distinction is in habit, which admits of their being 
arranged under two sections, one having an elongated 
caudex, and the other with contiguous cwspitose fronds. 
* Caudex elongated surculate, Fronds distant, the fertile 
specially contracted ; primary veins undefined. 
Sp. N. nummularifolius (Sw.) ; N. rupestris (R. Br.) (v v.) 
N. serpens (Forst.) ; N. acrostichoides (Forst.) ; N. albicans ` 
(BL); N. Lingua (Thumb.) (v v.) ; N. tricuspe (Thumb.) 
(v v.) 
Oss.—The numerous and intermediate forms and sizes 
of the preceding species from different localities render it 
almost impossible to collate and separate them into distinct 
species when many specimens are brought under view. 
The different form and colour of the scales of the caudex 
indicate specific characters, but even that seems to alter 
according to age, 
** Caudez short, ccespitose. Fertile and sterile fronds 
nearly uniform. Primary veins defined. 
N. Gardneri (Metten.) (v v.); N. africana (Kunze); N. 
porosus (Wall); N. flocculosus (Don) ; Bedd, F. Brit. Ind. 
pl. 162 sub. ; N. costatus ( Wall.) (v v.) ; N. splendens e 
N. CNAA (Hook); N. subfurfuracea is deni. A 
Boothii: (Hook... 
T 
