












174 THE BRITISH FERNS. 
and is so thinly clothed with scales as to appear naked; whilst the 
leafy portion or lamina is comparatively short, being sometimes not 
more than an inch, rarely exceeding three or four inches long; the 
base is cordate, the apex obtuse, the margin more or less undulated 
lobed or contracted, and laciniately or crenately toothed. The 
fronds are more or less but irregularly marginate, most so towards 
the apex, where, at the termination of the costa, there is frequently 
formed by the epidermal development, an irregular pouch or 
pocket, as in peraferum (77). The costa on the upper surface is 
raised, and broken up into little irregular excurrent points, producing 
a murieate, or almost echinate ridge; and on the under side it 
frequently becomes excurrent in the form of a horn. The fronds 
are fertile in the upper portion, and the pouch is also fertile. This 
was found in Ireland by Dr. Allchin, and is a permanent interesting 
and unusual form. 
79. nudicaule (Allehin). The fronds of this exceedingly rare form 
are variable, being narrowish, cordate at the base, simple or mul- 
tifid at the apex, short or elongate, some of them pocketed, some 
marginate. The chief peculiarity of this variety, however, consists 
in the almost total absence of scales, a condition very unusual in this 
genus, but here so strongly marked, that in the vernation of the 
plants, the convolutions of the fronds which are to be developed for 
several years onwards are visible on the crown. The plants resemble 
rugosum (78) in their peculiar smooth appearance, but otherwise 
are quite distinct. It was found by Dr. Allchin in Ireland. 
80. siciforme (Woll.). This is the most slightly marginate of the 
varieties referred to the marginatum group, and is not always constant. 
The fronds are narrowish, less than a foot in length, and about an 
inch wide, subcordate at the base, lance-shaped, having somewhat 
flexuous or laterally waved margins which are slightly crenate, and 
obsoletely, though continuously, marginate beneath ; the apex being 
bluntish ; they are also supra-soriferous, but the upper sori are very 
small. It was found in Guernsey by Mr. C. Jackson. 
81. scabrum (Woll.). Thisis a very handsome variety, somewhat 
intermediate between the marginatum and muricatum groups. The 
whole plant is of vigorous growth, with fronds upwards of two feet in 
length, and nearly two inches broad; the base cordate or truncate 

