106 FERNS OF THE LAKE COUNTRY 



above, and all turned one way, as already described, 

 the outlines of the pinnae wedge-shaped, digitately 

 pinnatifid (like the fingers of a hand notched almost 

 to the bone). The extreme or ultimate lobes are 

 linear-obtuse with a spinulose-serrated margin. The 

 fronds when luxuriant have a tendency to become 

 branched. The veins are twice-branched, branching 

 alternately from the rachis, forking again so as to ex- 

 tend a venule to each segment ; and after leaving the 

 midrib are furnished with a narrow membranous leafy 

 whig or border (which the rib itself has not). The 

 sori are collected round the free ends of the veins and 

 contained in the urn-shaped covers or involucres, which 

 differ from those of H. Tunbridgense in being more or 

 less obviously stalked instead of sessile, and in having 

 their valves entire instead of serrated at the upper 

 margin. Mr. Clowes notices also a farther difference 

 between the species : that the fronds of H. Tunbridgense 

 are annual, " never grow more than one year;" while 

 those of H. unilaterale are perennial, lasting for several 

 years and annually renewing their growth, bearing 

 spores year after year. 



HABITATS. Patterdale, Ambleside (J. BowcrbanTc), 

 Stock Ghyll Force (Miss Beever), Dungeon Ghyll, 

 Scaw Fell (Black Eocks and Great End), Bowfell, 

 Ennerdale (Dr. Dickinson), Scale Force (H. C. Wat- 

 son), Honister Crag (Rev. G. finder), Gratesgarth 

 Dale, Borrowdale, Lodore (Miss Wright*), Keswick, 

 near Hawkshead (Miss S. Cowburri), Coniston Old 

 Man (Miss Beever), Silverdale (Miss Beever), Dale- 

 garth (Robsori), High Stile (Finder). 



