236 HISTORY OF BRITISH FERNS. 



The stems are usually, except at the base, furnished with 

 whorls of numerous simple branches, the number of the 

 branches generally corresponding with the furrows of the 

 stem. These are slender, four- or five-ribbed, and their 

 sheaths set nearly close, and terminate in pale brown lance- 

 shaped teeth, having a membranous border. 



In this species, when a section of the stem is examined, 

 it shows a series of prominent ridges on the outer face; 

 just within these, and over against the furrows, occur a 

 circle of moderate sized cavities; and alternating with 

 these, and near the inner margin, is a series of much 

 smaller circular cavities. The central cavity of the stem 

 is comparatively very small, not very much larger than the 

 series of openings near the outer surface. The resemblance 

 is considerable between its section and that of E. arvense. 



The fructification is a blunt oblong cone, more than an 

 inch long, terminating the main stem, and supported on a 

 stalk about equal to its own length above the uppermost 

 sheath. The whorls of scales in the mature cone are quite 

 separated, and expose the white spore-cases attached to the 

 margin. The scales in this species exceed a hundred in 

 number. The fructification is mature about June. 



Besides the more usual form just described, there are 



