140 Narrow-Leaved Chain-Fern 
ate, next oblong or obovate with cuneate or truncate base, then 
elliptical or oblong-ovate or oblong-lanceolate and early lobed 
below. From P]. XXXVII can be seen how, in subsequent leaves, 
the lobes enlarge, and more and more lobes are formed, from 
the part of the blade above the first lobes, which enlarge also; 
until the lobes become the primary segments and the part of the 
blade left above them forms the apical section of the mature leaf. 
These segments sometimes in turn become lobed. Their lobes 
are rounded, and, so far as I have seen, are less deep than the 
lobes of the primary segments in O. sensibilis. 
The margin of the blade, except at base, is more or less 
crenulate at first. Later the crenulation becomes serrulation. 
The number of teeth mostly corresponds with the number of 
marginal veinlets: except near the rachis, each marginal veinlet 
usually terminates within a tooth. 
The veins are free at first. The leaf’s primary midvein, if 
not evident at the beginning, becomes so before areola appear. 
One or two areole form first in the upper part of the blade while 
the blade is still simple. Others follow in subsequent leaves, 
forming downward on each side of the primary midvein, and 
thence outward until the margin of the blade has the appearance 
of cutting the network of veins: the marginal veinlets are mostly 
free. The primary midvein is finally more or less hidden in the 
rachis of the mature leaf. 
The midveins of the leaf’s primary segments (secondary 
midveins) are formed in the same way as in O. sensibilis, and 
start, as on that plant, from the ends of the paracostal areolz 
next the blade’s primary midvein. In the mature leaf they are 
more or less concealed in the segments’ midribs. The areolze 
between them, as in O. sensibilis, have the appearance of being 
