134 FIRST FORMS OF VEGETATION. 
so-called continent of Atlantis. It is worthy of 
remark that, unlike all other plants, lichens are 
more widely distributed in proportion as they are 
higher in organization and more complex in struc- 
ture; all the British species of the genera Sticéa, 
Usnea, Stereocaulon, Spherophoron, Ramalina, and 
Cenomyce, which exhibit the highest development of 
lichenose vegetation, being found in one or other 
of their numerous protean forms, under almost 
every condition of latitude, altitude, and climate, 
although it is only in the more southern regions, 
where the humidity and temperature are more 
uniform, that we find them in constant fructifica- 
tion. Many problems of great interest and diffi- 
culty are furnished by the geographical distribu- 
tion of our native lichens. The restriction of the 
Stictas, for example, which extend over a wide 
range of the earth’s surface, and have such powers 
of adaptation, to a few localities in this country, is 
a circumstance as singular as the parallel fact of 
the London Pride, which grows in the same locality 
as the Irish Sticta, and is confined exclusively to 
a few damp mountain climates, being neverthe- 
less the most easily grown and propagated of all 
border plants in gardens, even in the very heart of 
our large cities. We cannot account for the rarity 
of certain lichens that are capable of very wide 
distribution, any more than we can account for 
