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Acroftichum. Fructifications cover the entire 
diik of the leaf. We have twofpectes 
of this genus. They both grow out of 
the fiflures of rocks in Wales, &c. 
Pteris aquilina. This is our oulyfpecies of 
this genus, though there are, in different 
parts of the world, no lefs than 23. It 
is diftinguifhed from other ferns by the 
fructifications being in marginal lines. 
It is our moft common Fern, or female 
Fern, or Brakes, or, in Yorkfliire, 
Brackens. It is that fpecies commonly 
burnt for the afhes, which yield a large 
proportion of vegetable alkali. Lin- 
naeus gave it the trivial name of aqui- 
lina, from the fuppofed figure of the 
Imperial Eagle in the root when cut 
obliquely. Lightfoot fays, that pota- 
toes planted on this fern never fail to 
produce a plentiful crop ; that in Nor- 
mandy the wretched inhabitants are 
fometimes reduced to the neceflity of 
mixing its roots with their bread. I 
hope the revolution in France, will, in 
its confequences, relieve them from 
this neceflity. It was formerly much 
pfed medically in obftruftions of the 
vijcera, 
