The Coming of Verteh rates and Ulse of FisJies 



of ancient fishes. For it must be remembered 

 that this thickness of 2 to 4 inches means 

 a much greater thickness before the stratum 

 was placed under the pressure of miles of over- 

 lying rock. 



It is often thouo^ht that the sudden death 

 of so many individuals must have been brought 

 about by some violent catastrophe, but the 

 more we study the ways of Nature the more 

 apparent is it that it is not necessary to call in 

 the aid of an earthquake or a volcanic eruj)tion 

 to destroy animals on a large scale, and that it 

 may be brought about quite as effectually with 

 the expenditure of much less violence. A good 

 illustration of this was the destruction of ani- 

 mal life on the California coast, near San 

 Pedro, in the summer of 1901, when many 

 fishes, mollusks, and sea-cucumbers were killed 

 by the sudden increase in number of a minute 

 organism belonging to the infusoria. Why 

 this little infusorian should have suddenly 

 become abundant we do not know, but as 

 it died in vast numbers it seems to have poi- 

 soned the water, and to have caused great 



93 



