DIFFICULTIES AND OBJECTIONS 225 



and the Laurentian — all to us yet almost tenant- 

 less, except for the few organisms which, like stray 

 shells cast upon the beach, or a far-off land dimly 

 seen in the distance, incite to further researches, 

 and to the exploration of the unknown treasures 

 that still lie undiscovered. It would be a suitable 

 culmination of the geological work of the last half- 

 century, and one within reach at least of our 

 immediate successors, to fill up this great blank, 

 and to trace back the Primordial life to the stage 

 of Eozoon, and perhaps even beyond this, to pre- 

 decessors which may have existed at the beginning 

 of the Laurentian, when the earliest sediments of 

 that great formation were laid down. Vast un- 

 explored areas of Laurentian and Huronian rocks 

 exist in the Old World and the New. The most 

 ample facilities for microscopic examination of 

 rocks may now be obtained ; and I could wish 

 that one result of the publication of these pages 

 may be to direct the attention of some of the 

 younger and more active geologists to these fields 

 of investigation. It is to be observed also that 

 such regions are among the richest in useful 

 minerals, and there is no reason why search for 

 these fossils should not be connected with other 



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