da. ub 
CHARACTERS OF TRIBES AND GENERA. 901 
... Although they agree in general habit they have never- 
P M 
theless been arranged by different authors under no less 
than at least six genera, the technical characters being 
chiefly derived from slight differences in the venation and 
position of the sori—for instance, Sagenia is characterised 
by Presl as having no free veinlets, but I find that that 
character is not constant, for in different specimens of the 
same species some have the venation of Sagenia, and others 
have free veinlets as in Aspidium, and sometimes the two 
forms are found on the same frond; the characters of the 
other genera of authors are also, I consider, untenable. 
I therefore retain them under Zspidium. 
Tt often happens that the indusium is soon deciduous, 
and therefore when absent this genus cannot be distin- 
guished from Dictyopteris and Dryomenes; also in some' 
species, as for instance the well-known Aspidiwm macro- 
phyllum, the indusium is as often reniform as peltate. ‘This 
difference has led the author of the “Synopsis Filicum” 
to consider the reniform as the normal form, and accord- 
ingly places 4. macrophyllum and other allied species 
in the genus Nephrodiwm, from which they differ entirely 
in habit. 
In the “Gartenflora,” 1866, page 335, Dr. Regel had 
characterised a new genus under the name of Gramma- 
tosorus, which is accompanied by a figure. It, however, 
appears to me to be founded on what may be termed an 
amorphous form of the sori of Aspidium alatum of Wallich, 
a large-growing Indian species, beariug numerous irregular 
small sori, which in specimens from Malacca are irregular 
. and confluent, forming linear transverse sori analogous to 
Meniscium, while others on the same segment form linear 
. sori parallel with the primary veins. The same variableness ` 
n the form of the sori is also to be found in A. irreguum 
