INTRODUCTION. 7 
in the economy of nature. Like many decayed 
families whose founders were kings and mighty 
heroes, but whose descendants are beggars, they 
were once the aristocracy of the vegetable king- 
dom, though now reduced to the lowest ranks, and 
considered the canaille of vegetation. Geology re- 
veals to us the extraordinary fact, that one whole 
volume of the earth’s stony book is filled almost 
exclusively with their history. Life may have 
been ushered upon our globe through oceans of the 
lowest types of conferve, long previous to the de- 
posit of the oldest palzozoic rocks as known to 
us ; and for myriads of ages these extremely simple 
and minute plants may have represented the only 
idea of life on the earth. But passing from conjec- 
ture to the domain of established truth, we know ofa 
certainty that at least throughout the vast periods 
of the ‘carboniferous era, ferns, mosses, and still 
humbler plants, occupied the throne of the vege- 
table kingdom, and, by their countless numbers, 
their huge dimensions, and rank luxuriance, covered 
the whole earth with a closely-woven mantle of 
dark green verdure—from Melville Island in the 
extreme north to the islands of the Antarctic 
Ocean in the extreme south. The relics of these 
immense primeval forests, reduced to a carbona- 
ceous or bituminous condition by the secret re- 
sources of nature’s laboratory, are now buried deep 
