254 
ASPLENIACE^. 
white involucre ; this involucre soon disappears, and the clus- 
ters generally become nearly circular and somewhat crowded ; 
they are sometimes so large and crowded when ripe as to be 
quite confluent. 
Contrasted with the ubiquitous species which I shall next 
describe, Asplenium lanceolatum may be known by the relative 
length of the lower pairs of pinnae : in lanceolatum the first 
pair is often shorter than the second, third and fourth, but this, 
as pointed out to me by Miss Griffiths, is far from being univer- 
sally the case, still they are not longer, the first to the fourth 
pair inclusive being nearly of equal length and size ; in Adian- 
tum-nigrum, on the contrary, the first pair of pinnae are mani- 
festly the longest, and the remainder gradually decrease in 
length, the form of the frond being deltoid : in lanceolatum the 
pinnae are somewhat in pairs, although, strictly speaking, not 
opposite ; in Adianturn-nigrum they are uniformly alternate : 
in lanceolatum they are set on at nearly right angles with the 
main stem ; in Adianturn-nigrum they form an acute angle with 
the stem ; in lanceolatum the pinnules are rounder and blunter 
than in Adianturn-nigrum^ a character which, as we have seen, 
attracted the notice of the all-observing Kay : the situation of 
the capsules on the lateral veins is also different, being in lan- 
ceolatum much nearer its extremity than in Adianturn-nigrum. 
