INTRODUCTION . 3 
the largest and strangest forms of life that once lived, and try 
to picture them as they really were when alive, whether walking 
on land, swimming in the sea, or flying in the air; to understand 
the meanings of their more obvious structures; and to form some 
conclusions with regard to their habits, as well as to find out, 
if possible, their relations,—as far as such questions have been 
answered by those most qualified to settle these difficult 
matters, 
All technical details, such as the general reader is unfamiliar 
with, will be as far as possible suppressed. Let us fancy a long 
procession of extinct monsters passing in single file before us, 
and ourselves endeavouring to pick out their “points” as they 
present themselves to the eye of imagination. It is not, be it 
remembered, mere imagination that guides the man of science 
in such matters, for all his conclusions are carefully based on 
reason; and when conclusions are given, we shall endeavour to 
show how they have been arrived at. 
For millions of years countless multitudes of living animals 
have played their little parts on the earth and passed away, to be 
buried up in the oozy beds of the seas of old time, or entombed 
with the leaves that sank in the waters of primeval lakes. The 
majority of these perished beyond all recovery, leaving not a 
trace behind; yet a vast number of fossilised remains have been, 
in various ways, preserved; sometimes almost as completely as 
if Dame Nature had thoughtfully embalmed them for our 
instruction and delight. 
Down in those old seas and lakes she kept her great museum, 
in order to preserve for us a selection of her treasures. In 
course of time she slowly raised up sea-beds and lake-bottoms 
to make them into dry land. This museum is everywhere 
around us. We have but to enter quarries and railway cuttings, 
