192 
HISTOEY OF BRITISH FEENS. 
in the form of an urn or vase, and within them bearing the 
fructification. 
The fronds are pendulous, and vary from an angular- 
ovate to a lanceolate form, the divisions being considerably 
undulated, so that they acquire a crisped appearance. The 
first series of lobes are usually of an ovate-lanceolate form ; 
the next series shorter, more ovate, and the third series of 
divisions narrow, more or less linear. The ultimate 
branches of the veins which extend into the divisions of 
this third series, end just at or within the apex of the 
lobes if they are barren ; but if they are fertile, they are 
produced beyond the margin, and surrounded at the base 
by the urn-shaped involucre, within which the spore-cases 
are placed. Sometimes the involucre is so placed as to 
appear immersed within the margin, but it more frequently 
projects beyond the margin. There is also considerable 
variation as to the length to which the bristle-like recep- 
tacle is extended beyond the involucre ; sometimes scarcely 
exceeding it in length, and sometimes being four or five 
times as long. 
The variety Andrewsii, is the lanceolate form of this 
plant, in which the pinnae or first set of divisions arc 
narrow and distant ; it is tolerably distinct from the 
