Vlll PREFACE. 



the dawn of life, and cannot doubt that the present 

 work will meet with at least as much acceptance as 

 that in which I recently endeavoured to picture the 

 whole series of the geological ages. 



I have to acknowledge my obligations to Sir W. 

 E. Logan for most of the Laurentian geology in 

 the second chapter, and also for the beautiful map 

 which he has kindly had prepared at his own ex- 

 pense as a contribution to the work. To Dr. Car- 

 penter I am indebted for much information as to 

 foraminiferal structures, and to Dr. Hunt for the 

 chemistry of the subject. Mr. Selwyn, Director of 

 the Geological Survey of Canada, has kindly given 

 me access to the materials in its collections. Mr. 

 Billings has contributed specimens and illustrations 

 of Palaeozoic Protozoa; and Mr. Weston has aided 

 greatly by the preparation of slices for the micro- 

 scope, and of photographs, as well as by assistance 

 in collecting. 



J. W. D. 



McGiLL COLLEGE, MONTREAL. 

 April, 1875. 



