WILSON’S FERN. 71 
regret it is so frequently disregarded in the sister 
- Science.) 
The caudex of this little fern is brown, siolonithes 
i and creeps very extensively among moss on the ledge 
_ of rocks in those mountain ravines where it occurs: in 
- such situations it is almost constantly wet from the 
j percolation of water. From this creeping caudex the 
fronds rise at irregular intervals, and not unfrequently 
in pairs; each has a slender erect stalk, which is 
_ longer than the leafy portion of the frond; it has a few 
nearly transparent pointed scales scattered near the 
_ base, where it is of a dark purplish brown, but green 
at the upper part: the leafy part of the frond is 
_ almost horizontal, being elbowed at its junction with 
the stalk; it is triangular in form and pinnate; the 
first or lowest pair of pinne are nearly opposite, and 
very much larger than the others, indeed nearly 
equalling in size all the rest of the frond; these 
disproportion between opposite pinnules decreases - 
_ gradually until at the tip of the pinna the corre- 
_ Sponding pinnules closely assimilate in size: the 
- lateral veins in the ultimate divisions are alternate, 
each generally terminating in a notch between two 
