GEOLOGY OF THE ST. CLAIR TUNNEL. 75 



tunuel is in all probability due to the fact that the Leda clay was deposited far from laud 

 in what was then a great westward extension of the Atlantic. 



In closing I desire to thank the various gentlemen to whom I am indebted for assist- 

 ance in carrying out this investigation. My thanks are due more especially to Sir Joseph 

 Hickson and Mr. Joseph Hobson for having the samples carefully collected and forwarded, 

 as well as for notes on their mode of occurrence, and to Sir William Dawson, at whose 

 request I undertook the examination of the same, for aid more particularly in the deter- 

 mination of the fossils. 



