PERNS OP GREAT BRITAIN. 27 



being the largest. Each branch is pinnate at the base, and 

 pinnatifid at the upper part : the pinnae are also pinnate 

 at the base, and pinnatifid and gradually tapering at the 

 top, the edges near the point being undivided, the pin- 

 nules aud lobes oblong and obtuse. The pair of pinnules 

 at the base of each pinna, close to the main stalk of the 

 frond, are so nearly of a size, and so placed, that when 

 the pinnae are exactly opposite, they stand in the form of 

 a cross ; the two nearest the summit of the branch being 

 smaller than the two opposite, and more nearly on a line 

 with the rachis. There is an angular bend in this fern, 

 just at the point of the rachis where the side branches 

 rise. 



A mid-vein winds through each lobe or pinnule, and the 

 lateral veins are usually alternate and without branches. 

 Each terminates at the margin, and the clusters of fruc- 

 tification, which are circular and of pale brown, are placed 

 at its extremity. Sometimes the clusters are densely 

 crowded ; in other specimens they are scattered and 

 remote. A large number of the fronds are barren, and 

 the fertile ones are generally taller than those without 

 fructification. 



The Three-branched Polypody is not unfrequent in 

 moist woods, and in stony, barren, mountainous places 

 both in England and Wales. It is common in Scotland, 

 and is very generally distributed, being found in every 

 country of Europe. Its underground stem is slender, 

 black, wiry, and creeping to a great distance. This fern 

 is by some writers included in the genus Polystichum or 

 Lastrea, and is also by Mr. Newman termed Gymnocar- 

 pium Bryopteris. The dried specimen of the Herbarium, 



