* 
548 THE CLUBMOSS FAMILY. “ 
northern and Arctic Asia, and North America. In Britain, in the moun- 
tainous parts of Scotland, northern England, Wales, and Ireland. #% 
summer and autumn [I. Moret, Moore, is a variety with leaves 18 inches 
long, found in Wicklow.] Modern botanists distinguish as L. echinospora, — 
Durieu, a form found in our mountain lakes, often growing with the 
common one, but said to be only where the soil is peaty. It differs chiefly 
in the larger spores covered with acute tubercles instead of being granulate 
only or smooth on the surface. A more distinct form referred to J. 
Hystrizx, Durieu (fig. 1261), occurs in moist sandy hollows on Laucresse 
Common in Guernsey. The rootstock is covered, outside the tuft of leaves, 
with a number of small, imbricate, toothed or jagged brown scales, which 
are the persistent remains of old leaves, and which are never observed in 
the common under-water forms. It remains to be seen how far this 
difference may be owing to situation. 
XCII. MARSILEACEA. THE MARSILEHA FAMILY. 
No true leaves. Fronds, as in /lices, proceeding from the 
rootstock and relled inwards at the top, barren ones either 
reduced to a narrow-linear stipes, or in an exotic genus bearing 
4 digitate leaflets; fertile ones sessile or on a short stipes, 
bearing a globular or ovoid utricle, usually called an involucre, 
and formerly considered as analogous to the spore-cases of 
Lycopodiacece, but which is really. the recurved fertile lamina 
with the margins united. Real spore-cases of two kinds, larger 
and smaller, as in Selaginacece, but arranged, as in Filices, inside 
the involucre, that is, on the under surface of the recurved 
frond, in sorz enclosed in membranous ¢emdusia, dividing the 
involucre into as many cells. | 
The Order was formerly supposed to be closely connected with Lycopo- 
diace@, in which the only British genus was included in our first editions, 
but its still nearer relation to Filices has been well pointed out chiefly by 
German botanists. It contains only one genus besides the British one. 
I. PILULARIA. PILLWORT. 
Rootstock creeping under water, with subulate, barren fronds, almost 
solitary at the nodes. Involucres (or fertile fronds) almost sessile on the 
stock, globular. Sori 2 to 4, vertically adnate, their indusia dividing the 
involucre into 2 to 4 cells, and each consisting of numerous spore-cases, — 
the lower ones few and larger, the upper ones numerous, minute, and 
powdery. . 
Besides the European species, which is also in the southern hemisphere, — 
there is a distinct North American one. ie 
1, PB. globulifera, Linn. (fig. 1262). Creeping Pillwort.—The 
slender rootstock often creeps to a considerable length, rooting at every 
node. Barren fronds filiform, of a bright green, like the leaves of Isoetes, 
varying from 1 to 3 inches in length. Involucres like little pills, nearly 
2 lines diameter, covered with short hairs. 
