THE MOUNTAIN BLADDER FERN 
297 
the pair of pilings next above the lowest ; but this pair, 
being much smaller and less divided than the lowest pair, 
the difference is not so prominent. On the third and 
succeeding pairs of pinnae above the base of the leafy part of 
the frond the upper and lower pinnules are nearly equal in 
length. The subdivision of the pinnae becomes less and less 
upwards as they become shorter and narrower, until at length 
they are merged in the apex of the frond. The venation is 
more or less complex according to the more or less divided 
form of the pinnae. In each ultimate division, whether it be 
a secondary pinnule or a lobe, there is a mid-vein, with 
venules branching into all the subdivisions, and it is noticeable 
that the veins terminate, not within the lobes formed by the 
serratures, but at the points formed by the clefts between 
two serratures. The sori are numerously scattered about 
upon the under surface of the frond, each sorus covered by 
the bulged or hood-like indusimn. There are no variations 
from the normal form of Cystopteris montcma. 
Distribution. — This elegant little Fern has a wide range 
throughout Europe, occurring in the following countries : 
Denmark, France, Germany, Hungary, Italy, Lapland, 
Norway, Spain, and Sweden. It has also been found in 
Asia and in North America. In the British Islands this is 
one of the rarest species. It is stated to have been found on 
Mount Glyder in North Wales, but there is some doubt as 
to the accuracy of the statement. In Scotland it was first 
discovered in 1836, on Ben Lawers, in Perthshire. Subse- 
quently it has been found in the same neighbourhood at 
Corrach Dll’ Oufillac-h, in the Meal Oufillach mountains, 
lying between Glen Lochy and Glen Doc-hart in Perthshire. 
Since then it has also been found in Canloehen, at the head 
of Glen Isla, Clova, in the county of Forfarshire. 
Culture. — The same soil should be used in the cultiva- 
tion of Cystopteris montana as that suggested for the two 
T 
