LICHENS. 97 
the mosses. These capsules, though thickly 
scattered over the crust, are so minute as to be 
scarcely distinguishable by the naked eye, but 
under the microscope they present a truly lovely 
appearance. They are cup or urn-shaped, of a 
coal-black colour, and supported by a slender 
stalk about the thickness of a horse-hair, At an 
early stage they are covered with a very delicate 
veil, which stretches completely over their mouth ; 
but this soon vanishes, and exposes to view a 
mass of black or brown seeds, like the ovule in an 
acorn, which the slightest touch of the tiniest 
insect’s wing can dislodge, and send away on the 
breeze in search of a habitat for another colony. 
Most of the crustaceous lichens are merely grey 
filmy patches inseparable from their growing 
places, indefinitely spreading, or bounded by a 
narrow dark border, which always intervenes to 
separate them when two species closely approxi- 
mate, and studded all over with black, brown, or 
red tubercles. The foliaceous species are usually 
round rosettes of various colours, attached by 
dense black fibres all over their under-surface, or 
by a single knot-like root in the centre. Some 
are dry and membranaceous; while others are 
gelatinous and pulpy, like aérial sea-weeds left 
exposed on island rocks by the retiring waves of 
an extinct ocean. Some are lobed with woolly 
G 
