BRISTLE FERN. 
313 
dilated portions being slightly transparent. I have attempted 
to show the structure of these bristles in the figure which I have 
introduced in the margin. Inter- 
mixed with these bristles are others 
much finer, much shorter, and more 
transparent ; and these, under a lens 
of sufiicient power, are also found 
to exhibit traces of articulation. 
The tomentose appearance of the 
roots is due to these minute bristles. 
The form of the fronds is be- 
tween lanceolate and triangular, 
those from Glouin Caragh approach- 
ing the former, those from Kil- 
larney the latter form. They are pinnate, the pinnae being- 
alternate and pinnate, and the pinnules deeply divided or pin- 
natifid. Perhaps it would be more correct to describe the hard, 
wiry, stem-like veins, as thus divided, and to say that each of 
these veins is furnished on each side with a semi-membranous 
wing extending throughout its length, for this is really the case 
in all the Hym€nop1iyllace(B that I have examined : the entire 
frond is composed of these wings, and consequently all its divi- 
sions are narrow and linear. This wing extends also to the 
stem, which is about equal to half the frond in length. 
The fructification may be thus described : the cluster of cap- 
sules is small and nearly spherical, and is attached to the centre 
of a vein after its ultimate division : at the point of attachment 
the wing partially loses its green and semi-membranous ap- 
pearance, becomes more opaque and of a whitish colour, and 
assumes a form something like that of a champagne-glass around 
the cluster of capsules ; the cap suliferous vein passes through 
this cup, and projects beyond it, often exceeding it four times in 
length. It is the general custom of botanists to speak of the 
cup as an involucre^ and of the bristle-like exserted vein as a 
receptacle. 
It has been lately supposed by many excellent botanists that 
there are two Irish species of Trichomanes , — the Killarney and 
the Glouin Caragh plants : I will now proceed to lay before my 
