XVI INTRODUCTION. 



instances in which even the local identity of beds cannot be ascertained 

 by their mineral characters and relative position alone, and in some of 

 these my opinion will be found to differ from that of the authors of the 

 " Survey," in consequence of their having rejected the principle of identi- 

 fication by the organized fossils, a principle which I consider as the most 

 important yet established in geological science, and of which I trust 

 that the present work will be found to furnish some new and strong 

 confirmations. 



I cannot omit this opportunity of expressing my sincere thanks to 

 the Officers of the Philosophical Societies of Yorkshire, Leeds, Hull, 

 Whitby, and Sheffield, for the liberality with which they have opened 

 to me their rich and valuable museums ; as well as to the proprietors 

 of above twenty private cabinets, who have zealously forwarded my 

 views. To those friends who have kindly interested themselves in the 

 success of my publication, I have endeavoured to prove my sense of 

 obligation by devoting myself to render it more worthy of their patron- 

 age. But there is one individual whose constant and considerate 

 benevolence, warm encouragement, and valued participation in my geo- 

 logical pursuits, demand my highest thanks ; and those only who like 

 me have found unexpected kindness and unmerited attention, can 

 fully understand the feelings with which I mention the Reverend 

 W. V. VEB.NON, President of the Yorkshire Philosophical Society. 



