CHAPTER I. 
HOW EXTINCT MONSTERS ARE PRESERVED. 
*Geology, beyond almost every other science, offers fields of research 
adapted to all capacities and to every condition and circumstance of life in 
which we may be placed. For while some of its phenomena require the 
highest intellectual powers, and the greatest attainments in abstract science for 
their successful investigation, many of its problems may be solved by the most 
ordinary intellect, and facts replete with the deepest interest may be gleaned 
by the most casual observer.’-—MANTELL. 
LET us suppose we are visiting a geological museum for the first 
time, passing along from one department to another with ever- 
increasing wonder—now admiring the beautiful polished marbles 
from Devonshire, with their delicate corals, or the wonderful 
fishes from the Old Red Sandstone, with their plates of enamel ; 
now the delicate shells and ammonites from the Lias or Oolites, 
with their pearly lustre still preserved; now the white fresh- 
looking shells from the Isle of Wight ; now the ponderous bones 
and big teeth of ancient monsters from the Wealden beds of 
Sussex. The question might naturally occur, ‘‘ How were all 
these creatures preserved from destruction and decay, and sealed 
up so securely that it is difficult to believe they are as old as the 
geologists tell us they are?” It will be worth our while to con- 
sider this before we pass on to describe the creatures themselves. 
Now, in the first place, ‘‘fossils” are not always “‘ petrifactions,”’ 
as some people seem to think ; that is to say, they are not all 
turned into stone. ‘This is true in many cases, no doubt, yet one 
frequently comes across the remains of plants and animals that 
