GUIDE TO THE FOSSILS IN THE 
NATIONAL MUSEUM. 
INTRODUCTION. 
Fossils, which we find embedded in the solid rock, or 
which we dig out of the ground, are the remains of once 
living animals and plants. 
Our marble halls, with all their quarried stones — 
What are they but the bleached and whitened bones 
Of countless generations piled on high. 
The Limestone, the Mudstone, or the Sandrock which 
we often find enclosing fossils, may represent the deposit of 
an old sea-bed, a lake bottom, or the accumulation of a river 
or swamp. Over these ancient surfaces there once lived and 
crawled the extinct animals whose remains are now preserved 
as petrifactions. In the case of the plant remains, these may 
have been rooted in the mud of a swamp, if found in the 
position of growth, or they may have been washed down 
by rivers and streams, as, for example, in the case of the 
brown coal formation. 
It was supposed by some of the ancient writers that these 
fossil remains were actually generated within the mud or 
slime and that they lived in the position where they are now 
found. Other authorities of the time thought them to be 
freaks of nature — lusus naturae. 
Aristotle, the Greek philosopher, imagined fossils to have 
been produced by a plastic force in the rock, and this opinion 
was long accepted. 
It was not until the beginning of the 18th century that the 
true nature of fossils was understood. It was also realized 
that these ancient animals could not all have lived at the 
same time, so that their presence was not easily explained 
by a Universal Flood. 
Geological investigations, such as those made by Leonardo 
da Vinci, the great civil engineer and artist of the early part 
of the 16th century, proved that the land and sea had ex- 
changed relative positions, and that what was once a sea-bed 
has become dry land. 
1375 3 
