20 POLYrODIUM ROREETIANVM. 



plant, very readily cultivated; and growing in exposed sunny 

 parts of the Fernery, is a useful species if given suitable soil 

 and good drainage. The soil should be loamy, with a small 

 portion of chalk or limestone, 



JPoltjpodium Rohertiamim, better known as the Pohjpodium 

 calcareum, is found in several parts of Cumberland, in Derby- 

 shire, (at Matlock, Buxton, and Wirksworth, where it grows 

 abundantly,) in Gloucestershire, Lancfashire, Oxfordshire, Somer- 

 setshire, Westmoreland, Wiltshire, and Yorkshire. In Wales — 

 Caernarvonshire, Denbighshire, and Glamorganshire. I believe 

 it is unknoAvn in Ireland and Scotland. Its most abundant 

 localities are Matlock, Buxton, and WirksAvorth, in Derbyshire, 

 (in the latter locality I have seen many phmts;) Besbury 

 Common, Gloucestershire; Arnside, Westmoreland; Settle and 

 Anster Rocks, Yorkshire; and Merthyr Tydvil, in Wales. 



Abroad it is a native of France, Switzerland, Germany, 

 Hungary, and Norway. On the Himalaya Mountains, and in 

 Canada and the United States. 



For some time there was a doubt as to whether this Fern 

 should take rank as a species, or be considered merely as a 

 variety of Polypodium dryopterts: our leading cryptogamic 

 botanists have long since settled this question, regarding it as 

 a distinct species. 



The fronds, which grow erect, rigid, and elongate at the 

 apex, are pentangular-deltoid and subternate, the lower branches 

 bipinnate at their base, and stalked. PinnjE obliquely-triangular, 

 opposite, and briefly stalked; the basal pair considerably the 

 largest, and bipinnate; the second pair briefly stalked or sessile, 

 and pinnato-pinnatifid; the remainder sessile, pinnate, and then 

 pinnatifid, becoming less and less divided towards the apex. 

 The pinnules of the basal pair of pinnro considerably larger on 

 the lower side: all others almost equal. Stipes much longer 

 than the rachis; base scaly, stout, pale green, lateral, and 

 adherent to the rhizoma. 



Rhizoina perennial, branched, creeping, and scaly; root-fibres 

 dark. 



Length of frond from eight to eighteen inches, sometimes 

 more; herbaceous and heavy greyish green, owing to minute- 

 stalked glands covering both frond and stem. 



Vernation circinate. 



