BOTANICAL APHORISMS, 187 
The character which Dr Smith has chosen for 
discriminating the genera in the Filices is the In- 
dusium, (§ 40. 122). As this character is easily 
seen, he observes how it separates, and in what 
order the seed-capsules under it are placed. In 
other Filices, that have not their fructification on 
the back of the leaf, we must resort to the figure 
of the fruit. 
The Musci frondosi, (§ 122), have of late been 
very accurately investigated, and their flowers and 
fruit are known: we are therefore now able to dis- 
tinguish their genera better than formerly, the cha- 
racters of which are taken from the peristoma, 
(§ 111. d). This organ aitords a number of cha- 
racters, that are steady and easily seen. 
The Musci hepatici, (§ 122), are also arranged 
in genera by the fruit, according to the mode in 
which it opens. 
The Algez, (§ 122), have their genera ascertain- 
ed according to the form of the fruit, so far as this 
is known ; but the external form must not be em- 
ployed for this purpose. 
The same characters are used in the Fung, 
(122), but these are so numerous, and their dura- 
tion is so short, that the industry of many natu- 
_ralists in different places will be required to fill up 
the blanks in this order. 
It remains to be observed further, that all genera 
must be determined by the flower and ui and 
never by the root, the stem, or other parts, not 
éven by the involucrum. 
§ 182. 
