THE BLACK MAIDENHAIR SPLEENWORT 
357 
and in tlie pinnules next the main racliis — again divided into 
irregularly-shaped lobes, which have their margins beau- 
tifully cleft or serrated. The basal pinnge are the longest and 
most divided. The next are smaller and less divided, and 
succeeding ones become smaller and less divided in grada- 
tion, until they are merged in one point at the apex of the 
frond. In the same way the basal pinnules of each pinna 
are longer and more divided than those at its apex, which 
is acute-pointed, and the lobes of the pinnules are subject to 
precisely the same arrangement from base to apex, and 
there is the same merging of leafy divisions in the apices of 
pinnules and lobes as in the apex of the frond itself. The 
venation is singularly well defined, and consists of a mid- 
vein, traversing the pinnule or lobe — whichever is the 
ultimate division of the frond — with venules simple or 
forked branching from the mid-vein, obliquely towards 
the marginal teeth. The elongated sori follow the same 
direction as these veins, and are covered when young by 
pale green — almost white — indusia. After a little time the 
swelling of the spore cases bursts the indusia, the latter 
subsequently disappear, and finally the sori become con- 
tiuent, often densely covering almost the entire under surface 
of the frond, the rich dark brown colour of the spore cases 
forming a striking and beautiful contrast with the dark 
shining green colour of the upper side of the frond. The 
rootstock is furnished with very long and very abundant 
fibrous rootlets. There are about twenty-five departures 
from the normal form of this Fern. 
Distribution. — At altitudes varying from the sea level — 
it often grows on sea-girt rocks — to two thousand feet above 
it, the Black Maidenhair Spleenwort is found in the following 
parts of Europe, namely, Albania, Austria, the Balearic 
Isles, Belgium, Bohemia, Corsica, Croatia, Cyprus, Dalmatia, 
Denmark, France, Germany, Greece, Hungary, Italy, 
