POLYPODICM, 77 



lateral branches of the frond take their rise, but this 

 feature is much more obvious in P. Dryopteris. The 

 fronds are divided so that each branch is pinnate at the 

 base, and pinnatifid towards its point ; the pinnse are also 

 pinnate at their base, then pinnatifid, becoming acute and 

 nearly entire at the point ; the pinnules and ultimate 

 lobes are oblong and obtuse. The pair of pinnules at the 

 base of each pinna, close to the principal rachis, are placed 

 so that Avhcn the pinnas are exactly opposite they stand 

 in the form of a cross ; the two towards the apex of 

 the branch being smaller than the opposite pair, and 

 more nearly parallel with the rachis. The pinnules or 

 lobes have a rather wavy midvein, from which the venules 

 branch out alternately, being, in those of moderate size, 

 simple, with a sorus near their extremity, and in those 

 which are larger and more compound, branched, with a 

 sorus on the lower branch. The fructification is very un- 

 equally produced in different seasons and localities, being 

 sometimes crowded, and at other times very sparingly scat- 

 tered over the fronds. 



P. Dryopteris is not an uncommon species, but it occurs 

 only in mountainous situations and the drier parts of 

 damp woods : in England it is found mostly in the north ; 



