BRITISH FERNS. 69 



they soon begin to droop, and finally become quite pendulous : 

 they arrive at maturity in September, and continue perfectly 

 green and vigorous throughout the winter, and until the ensuing 

 May or even June : they are always fertile. 



The form of the frond is triangular, the apex being acute and 

 attenuated ; it is pinnate : the pinnae are triangular, acutely 

 pointed, pinnate and alternate ; the pinnulae again are alternate 

 and triangular, and the lower ones pinnate or pinnatifid, with 

 their lobes notched : the fronds represented are of the natural size, 

 but are drawn from fronds which may be less than the average. 



The lateral veins in the pinnulae or lobes, as the case may be, 

 are irregularly alternate, and generally forked after leaving the 

 midvein, and one or both branches of this divided vein bears an 

 elongate linear mass of thecae ; these masses are always situated 

 near the midvein, and at first are completely covered by a long, 

 narrow, white, scale-like indusium, which opens towards the 

 midvein, and as the thecae swell and approach maturity, it is 

 raised, pushed from its site, turned aside, and finally entirely 

 disappears, and the under-surface of the frond becomes a con- 

 tinuous mass of rich brown seed. 



The superior length of the lower pinnae, and the oblique angle 

 at which these, and indeed all the pinnae, are attached to the 

 rachis, and, lastly, the more central situation in the pinnulae 

 occupied by the thecae, are characters by which this species may 

 be readily distinguished from the preceding. 



