THE POLYPODIES. 



31 



are of a dull deep green, more rigid, and without the marked 

 deflection of the rachis so obvious in P. Dryopteris ; and the 

 young fronds, instead of being rolled up in three little balls, 

 have their pinnae all rolled up separately. The glandular 

 surface of the frond is very readily seen with a good pocket- 

 lens, which is a necessary aid to the study of Ferns. 



Fia. 3. 



^. Polypodium Rolertlanum. 



This is one of the few Ferns which are found in calca- 

 reous or chalky soils. It is rare, and local in its distribu- 

 tion, being, we believe, almost confined to rocky limestone 

 districts, and occurring chiefly in the northern and western 

 parts of the island- 

 In cultivation, this species does not require so much mois- 

 ture and shade as most other Ferns, but a limestone soft is 

 not at all essential to its well-being; 



