120 HISTORY OF BRITISH PERNS. 



has a few scales of a blunt, ovate form, a membranous tex- 

 ture, and an uniform light brown colour. The pinnae are 

 elongate-triangular in their outline, the broadest occurring 

 at the base of the frond, the upper ones becoming gradually 

 narrower, but all of the same general form, namely, widest 

 at the base, gradually tapering to the apex. They are not, 

 in the usual form of the species, divided quite down to their 

 midrib, so as to become, in technical terms, pinnate, but 

 each segment is attached by the entire width of its base, and 

 connected by a narrow extension of its base with the seg- 

 ment next behind it ; all the segments having their apices 

 inclined rather towards the apex of the pinna. The lobes 

 of the pinnae are themselves oblong, with a rounded apex, 

 and a crenately toothed margin. 



The midvein of the lobes takes a tortuous course, and 

 gives off lateral branches which divide into several secondary 

 branches, one only of which, that nearest the apex of the 

 lobe, bears a sorus. The fructification is confined to the 

 upper portion of the frond, and often remarkably so ; less 

 frequently it extends downwards to the pair of pinnae next 

 above the basal ones. The spots of spore-cases are covered 

 by a kidney-shaped scale or iudusium, having an entire 

 margin, and become mature in August and September. 



