













170 THE BRITISH FERNS. 
length ; and commonly with the lamina barely exceeding an inch 
long, and from three to five-eighths wide. The fronds in general 
outline are mostly oblong and obtuse or truncate, sometimes calyci- 
form or cornute, deeply and irregularly marginate, the excurrent 
membrane being so much developed as to produce the appearanoe of 
the frond being split in two edgewise on each side the costa. The 
upper surface is irregularly verrucose. The fronds do not produce 
fructifieation, but in lieu thereof, curious little bulbils appear on 
their surface, and these ultimately form minute plants exactly like 
the parent. The fronds sometimes consist wholly of the stipes and 
costa, the latter being tapered off and pointed like an awl, and no 
leafy or herbaceous portion being produced. This curious variety 
was raised several years since by Mr. Wollaston. 
69. fimbriatum (Allchin). This unique variety bears two sorts of 
fronds, besides the abortive ones consisting of hooks and points pecu- 
liar to this group. The broader ones are three-quarters of an inch 
wide, and six to nine inches in length, narrowed and truncate at the 
base, often with small separate lobes; the margins irregularly frilled, 
crenate-lobate with the lobes crenate, and somewhat undulated ; the 
sori are mostly exterior to the excurrent membrane, which is the 
same as in other marginate forms and very distinctly developed. 
The other kind of frond is long and very narrow, being about a 
quarter of an inch wide, and from nine inches to a foot in length, 
more nearly resembling a winged rachis than a frond, the leafy part 
on either side being of about the same width as the rachis itself; 
its margins are frilled as in the other form, but more minutely 
divided, and the disrupted membrane recedes even to the rachis 
itself. It is a very neat and curious plant, and was found some 
years since, in Guernsey, by Dr. Allchin. 
70. constrictum (M.). A curious form, formerly described under 
this name, having medium-sized fronds in which the upper half was 
broad and almost normal, and the lower half, except the extreme 
base where the usual cordate lobes were developed, was contracted 
to less than half the width, deeply crenated and marginate, has not 
proved constant. It was found by Mr. James in Guernsey. Another 
form to which the name may be transferred, also found in the same 
island by Mr. James, is permanent. This has fronds about six inches 

