34 
THE LIME- STONE POLYPODY. 
the sori are small and round, consisting of numerous 
crowded spore-cases, entirely without indusia, arranged 
in linear sub-marginal series along each side of the 
lobules, or in series between the midrib and margin 
when the lobules are but slightly developed, — often 
more or less confluent. Spore-cases pale brown, 
roundish obovate, small, and numerous. Spores 
ovate or oblong, somewhat granular. 
The Lime-stone Polypody, as its name infers, is 
found usually on exposed rocky limestone tracks : 
growing there very abundantly. In cultivation, how- 
ever, a lime-stone soil is not essential to its well-being. 
Like the generality of ferns, it requires good drainage ; 
but bears the sun more than most others. It grows 
almost throughout Europe, in Canada, and the United 
States of America ; and has been gathered by Dr. 
Hooker and Dr. Thomson on the Himalaya Mountains 
at the elevation of 6,000 feet. 
Habitats. 
Scale Force (J. Robson), Whitbarrow, Newbiggin 
Woods, Gilt Quarries, Baron Heath, Arnside Knott, 
Hutton Roof Crags, Farleton Knott, Caskill Kirk, &c. 
Only one variety : 
variabile, — Whitbarrow, J. M. Barnes and F. Clowes. 
