CHARACTERS OF TRIBES AND GENERA, WICH 
they are epigeons, of a flaccid soft texture, easily affected 
by drought; the well-known Lastrea Filiz-mas, L. Oreop- 
teris, and L. dilatata being examples; or they are more 
firm, hard, and spiny, as in Polystichum aculeatum and 
allies, 
The most important divisional characters consist in the 
veins being free or anastomosing in various ways, and in 
the sori being naked or furnished with an indusium, which 
in some is very small and fugacious, soon becoming obli- 
terated, and which leads to some species being placed in 
indusiate genera by some authors, while others place them 
among the non-indusiate. 
The normal character of the indusium is either lateral 
(interiorly attached) or peltate; in some multifid fronds, 
such as Lastrea deparioides, the indusium appears to coincide 
with the crenule or dent of the margin, so as to form a 
cyst similar to that of Microlepia, and in Trichiocarpa it is 
exserted beyond the margin in the form of a calyciform 
cyst, as in Deparia. In Amphiblestra the sporangia are 
produced in an irregular row close to the margin, which ` 
is inflexed in the form of an indusium like that of Pteris, 
but from which it differs entirely in habit and venation, 
which is that of Aspidiwm; and as regards Isoloma, 
although it has marginal sori similar to Lindswa, it never- 
theless differs entirely in habit, which agrees perfectly 
with that of Nephrolepis. In Hypoderris the sori are 
discal and furnished with a small membraneous calyciform 
indusium similar to that of Woodsia. Although these four 
genera differ in the nature of their fructification from the 
normal character of the indusiate Phegopteridew, I never- 
theless deem it best to place them in it, and as near as 
possible in contiguity with the genera to which they are ` > 
most nearly allied in habit and venation, Ge 
