- CHARACTERS OF TRIBES AND GENERA. ` 0. 978 
Tribe 19. ADIANTEZE. (Plate 19.) 
Vernation fasciculate or sarmentose, generally hypogeous, 
and becoming cwspitose. Sori marginal, transverse, Ob- 
long, linear, or punctiform. Jndusium lateral, exterior 
attached, bearing the sporangia on its under surface. 
Oss.— This is truly a natural tribe of Ferns, having the 
smooth, polished, and flaccid character of Lindsea, but 
differing in the indusium being attached exteriorly, and its 
under surface venose, and bearing the sporangia, which 
latter character distinguishes it from the tribe Pterideæ ; 
it is formed of a portion of the lamine of the margin of 
the frond, which is changed in texture, its form depending 
on the ultimate segments being entire, or more or less 
divided, thus varying from reniform, linear, to oblong, 
continuous, occupying the whole margin of the segments. 
Those with reniform indusia are distinguished from 
Cheilanthes not only by the indusium being sporangiferous 
on its disk, but also by its being produced on the con- 
vergent apices of two or more venules, whereas the sori of 
Oheilanthes are seated on the axis of a single venule, ter- 
minating in the axis of the indusium. 
In the “ Species Filicum " 109 species are described, but 
in the * Synopsis Filicum " the number is reduced to 62; 
the first number was arrived at by Sir W. Hooker, after 
more than half a century’s study of Ferns, and the latter 
number by the editor of the “ Synopsis " after three years’ 
study of Sir W. Hooker’s herbarium. This is a striking 
example of the different views taken by Pteridologists as 
to what constitutes species.* 
` * In the Appendix to the " Synopsis Filicum ” nineteen additional 
Species are described. 
