252 
HISTORY OF BRITISH FERRS. 
stems. These are quite dissimilar in their appearance, 
some being short, quite simple, and terminating in a cone- 
like head of spore-cases ; others being without fructification, 
taller, and producing several whorls of long, crowded, slen- 
der branches ; whilst a third kind, of ‘common though not 
constant occurrence,^ produce whorls of branches and cones 
also. In the production of these three kinds of stems it 
serves to connect, through E, syhaticum^ that group in 
which the fertile and barren stems are successive and 
altogether unlike, with that in which any of the stems 
indifferently — at least as to external appearances — bear the 
fructification, all being of similar habit. 
The fertile stems grow about six inches high, and are 
quite branchless ; they are of a pale yellowish-green, having 
numerous joints, the large loose funnel-shaped sheaths 
produced at these points almost covering the stem, as 
usually described and figured ; but in our specimens they 
are much less crowded, a space of from half an inch to an 
inch occurring between the adjoining sheaths. These 
sheaths are still paler-coloured than the stem, often almost 
white, with a dark ring below the teeth, which are awl- 
shaped, pale-brown, with pale-coloured membranous mar- 
gins ; the teeth are about twenty — from twelve to twenty — 
