POLYPODIUM. 79 



base shorter than the sides, the stipes about equalling the 

 leafy portion in length. They are partially three-branched, 

 but the lateral branches are much smaller than the central 

 one, and attached to the stipes by a more slender rachis. 

 The lower branches are pinnate, with pinnatifid pinnae ; 

 the upper branch pinnate, with its lower pinnte again 

 pinnate, and the upper ones pinnatifid, as also is the apex 

 of the frond and of the lower branches. The pinnules or 

 lobes have a distinct midvein, with simple or slightly- 

 branched venules, near the termination of which, in a mar- 

 ginal series, the sori are produced. 



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 moisture and shade as most other Ferns, 

 but a limestone soil is not at all essential to its well-beinjr. 



The names of Polypodmm calcareiim, Phegopteris cal- 

 carea, Lastrea Bobertiana, and Gymnocarpium Bobertia- 

 num, have been given to this species. 



