emotion 
102 FIRST FORMS OF VEGETATION. 
profusion and attains a larger size in tropical 
than in temperate countries. Many exotic, and 
one or two European lichens occur on living 
leaves. These are principally developed on the 
upper surface, sometimes only superficially con- 
nected with the leaves, which afford them a basis 
of attachment and growth; and at other times 
originating like the fungi beneath the true cuticle, 
forming a carbonaceous, beautifully-sculptured 
crust and elegant fructification. The foliage of 
the Thibetian wonder may, therefore, be indebted 
for its singular markings to a species of Limboria; 
and the characters on the bark and branches may. 
have been caused by an unknown Opegrapha. 
In fact, the counterpart of these inscriptions has 
been discovered by Hooker and Thomson in 
Khasya, on the leaves of a species of Symplocos. 
Let us glance at some of the peculiarities of the 
lichens, and see if nature has not assigned them a 
higher and more important commission in her 
great household, than merely ornamenting old 
walls and ruins, and covering trees with a shaggy 
mantle. 
The lichens have apparently no affinity with 
' the mosses. Their appearance is altogether dif- 
ferent; and yet they approach the frondose divi- 
sion of the Hepatice or scale-mosses by the genus 
Endocarpon, which consists of a greenish leathery 
