LOWER SILURIAN FOSSILS. 43 



views so far as to suppose that the Old Red Sand- 

 stone marked the beginning of the rocks charged 

 with organic remains. He might, indeed, after a 

 search of many years, admit that here and there 

 some few and faint traces of fossils had been 

 found in still older states, in Scotland ; but he 

 might naturaUy conclude, that all pre-existing 

 fossiliferous formations must be very insignificant, 

 since no pebbles containing organic remains have 

 yet been detected in the conglomerates of the Old 

 Red Sandstone. Great would be the surprise of 

 such a theorist, when he learnt that in other parts 

 of Europe, and still more particularly in North 

 America, a great succession of antecedent strata 

 had been discovered, capable, according to some 

 of the ablest palaeontologists, of constituting no 

 less than three independent groups, each of them 

 as important as the ' Old Red ' or Devonian 

 system, and as distinguishable from each other 

 by their organic remains. Yet it would be con- 

 sistent with methods of generalizing not un- 

 common on such subjects, if he still took for 

 granted that in the lowest of these * Transition ' 

 or Silurian rocks, he had at length arrived at the 

 much-wished-for termination of the fossiliferous 

 series, and that nature had begun her work pre- 



