THE LIMESTONE POLYPODY. 95 
sori, so that the character is not distinctive. The species referred 
to this group possess, however, in common, a peculiarity of some 
importance, their fronds being adherent to, not articulated with, the 
creeping caudex. 
This species occurs we believe exclusively on exposed rocky lime- 
stone tracts. It is found plentifully in some parts of England, 
chiefly in the western, central, and northern districts, from Somer- 
setshire in the south-west, to Durham in the north; in the former 
district descending to about 250 feet above the sea, and in the 
north ascending to 900 feet or upwards. It also occurs plentifully 
in some parts of Wales. The calcareous hills of Gloucestershire 
seem, however, to be its head-quarters. It is not known to occur 
in Ireland, in Scotland with the adjacent Isles, or in the eastern 
counties of England. Its distribution is recorded as follows :一 
Peninsula.—Somersetshire: Bath; Cheddar Cliffs; Mendip Hills; 
Friary Wood; Hinton Abbey. 
Channel.— Wiltshire : Box quarries; Corsham, Dr. Alexander. 
Thames.—Oxfordshire. 
Severn.—Gloucestershire : Besborough Common, W. H. Purchas ; 
Rocks by the Wye, near Symond’s Yat; New Weir; Lydbrook, 
Forest of Dean; Cleeve Clouds and Windlass Hill, near Chelten- 
ham; Postlip Hill, and elsewhere on the Cotswolds; Cirencester, 
J. Buckman ; English Bicknor, A. T. Wilmot; Leigh Wood, near 
Bristol. Herefordshire: Colwall, near Whitchurch. Worcester- 
shire. Staffordshire. 
Trent.—Derbyshire: Matlock; Wirksworth ; Roadside under the 
Lover’s Leap, Buxton ; Bakewell, 7. Butler; Dovedale. 
Mersey.—Lancashire : Lancaster; Sheddin Clough, near Burnley; 
Broadbank. 
Humber.—Y orkshire : Ingleborough; near Settle ; Anster Rocks; 
Arncliffe; Gordale; Ravenscar, Waldenhead, J. Ward; near 
Bradford, J. T. Newboult ; near Sheffield. 
Tyne.—Durham: Falcon Clints, T. Simpson. 
Lakes.—Cumberland : Newbiggin Wood; Gelt Quarries; Baron 
Heath; Scale Force, J. Robson. Westmoreland: Arnside Knot; 
Hutton Roof Crags; Farlton Knot; Caskill Kirk. 

