242 HISTORY OF BRITISH FEKNS. 



are very dense, being compouridly branched. The side 

 branches, which measure about four inches in length, are 

 constantly branched at every joint with a whorl of branch- 

 lets averaging two inches in length, and sometimes these 

 branchlets put out another series of short branches. The 

 outline of the frond would be nearly pyramidal, were it not 

 that the extreme point becomes so slender as to be unable 

 to retain itself erect ; the lateral branches are all droop- 

 ing or deflexed, and hence the elegant appearance of the full- 

 grown fronds. The ultimate branches are three-ribbed, 

 which gives them a triangular form ; their joints terminate 

 in three long pointed teeth, one of the ribs extending undi- 

 vided to the apex of each tooth. The teeth are of the same 

 colour as the branch. 



The section of the stem shows a series of shallow ridges 

 and furrows ; opposite the latter a ring of largish cavities ; 

 and alternating with these on the inner side, another ring of 

 very minute cavities, these latter again alternating with a 

 circle of angular cavities close to the inner margin of the 

 tube. The central cavity measures about half the diameter. 



The fructification is an oblong-ovate cone-like head, con- 

 sisting of eighty or more pale brown peltate scales ranged 

 in whorls, and to which white spore-cases are attached. 



