234 POLYSTICHUM ACULEATUM. 
the end tooth inclines to one side ; the lowermost tooth 
on the upper edge forms somewhat of a lobe. The mid- 
vein of each leafit has alternate side-veins, and these 
side-veins are again branched ; of the upper side-veins 
that next the mid-vein bears a mass of fructification. 
The fructification is produced almost exclusively on the 
leafits at the top of the frond, and the masses form a 
parallel line of circles, gradually diminishing in size from 
the base of the leafit to its point on each side of the mid- 
vein. They often press against each other, but rarely run 
together. Each mass has a flat, circular cover, unnotched, 
and with an elevation in the centre when young. 
There are two varieties, which seem merely alterations 
of form, arising from accidental circumstances of soil 
and situation, and of which it is sufficient to say, that 
of obtusum the teeth are more scollop -shaped, yet 
prickly; and alatum has the leaflets connected by a 
wing proceeding from the sides of the stem. 
It is most common in the south of England in woods 
and on shady banks, especially if moist and stony. 
In England it has been found at Benroyd Clough, 
Norland, and Toadholes Wood, in Sowerby Dean, both 
near Halifax, and near Richmond, in Yorkshire; in 
Leigh, St. Anne's, and Stapleton Woods, near Bristol ; 
in Burton Wood, near Warrington, in Lancashire; in 
Shapscombe Wood, near Pain swick, Gloucestershire; at 
Ulverscroft Priory, in Charnwood Forest ; at the Valley, 
near Bromsgrove, in Worcestershire; in the Isle of 
Man ; at Elmdon House, Warwickshire ; on Little 
Warlev Common, Essex ; about Tunbridge Wells 
