154 IX. ASPLESIUM. 
however, the fronds are very nearly triangular in outline, 
when this species is not so readily distinguished from . I . 
Adiantuiit-nigrum, from which, nevertheless, it may be 
known by the form and submarginal position of its sori. 
The pinnules are usually obovate, but vary considerably in 
form, being sometimes much attenuated at the base, with 
the apex rounded ; sometimes blunt, both at the base and 
apex, becoming irregularly quadrate. In all cases they 
are indented on the margin with deep sharp teeth, the 
smaller pinnules being simply toothed and the larger ones 
near the principal rachis deeply cut and again toothed. 
The venation of each pinnule consists of a somewhat tor- 
tuous mid-vein, from which forked veins are produced, 
one venule extending to the point of each serrature. The 
sori are produced from the side of these veins and venules 
towards their extremity, without any regular order ; they 
are at first oblong, but become more or less circular in 
age, the thin white indusium by which they are covered 
in their earlier stages being soon obliterated, the sori be- 
ing often large, and frequently confluent when old. The 
indusium, which opens along its inner edge, is on that 
side usually slightly lacerated. The fructification is ma- 
ture in August 
This species is not very abundant, and is chiefly found 
near the sea-coast. The counties from which it is re- 
ported are Cornwall, Devon, and Somerset ; Gloucester, 
Kent, or Sussex ; Pembroke, Glamorgan, Merioneth, Car- 
narvon, and Denbigh. It is also found in the Channel 
Islands, in the middle and south of Europe, in Madeira 
and the Azores ; and, according to Link, in the west of 
Scotland near Gilphead, and^in Ireland; but we do not 
find these latter statements confirmed. 
It requires a mild sheltered climate, and is therefore 
not suited for rock-work, or exposed situations. Placed 
where it may have a moist and calm atmosphere, free 
drainage at the root, and a moderately elevated tempera- 
ture, it will grow freely, and under such circumstances 
