LIFE IN THE GREAT DEPTHS 109 



of a dredge or trawl from the depths of the 

 ocean strange creatures are obtained whose 

 anatomy, forms and characteristics upset all 

 our preconceived ideas of nature's laws in 

 respect to animal life. 



Moreover, we know very little about the 

 real life of prehistoric creatures. We find 

 their skeletons preserved in rocks, sand and 

 clay in the form of fossils, but in all proba- 

 bility only a very small proportion of the 

 creatures of those far-off times have been pre- 

 served in this way and every year new and 

 more remarkable fossils are discovered. 



At one time we know the sea covered nearly 

 the entire globe and countless thousands of 

 strange animals swarmed in the vast waste of 

 waters. Here and there, as the sea receded, 

 these creatures were left stranded or were 

 trapped within lagoons, bays and inlets and 

 their bones were left to be found by us as fos- 

 sils. 



The great majority of the marine crea- 

 tures of those past times no doubt escaped the 

 fate of their fellows and continued to dwell 

 safely in the sea as the oceans became smaller 



