PREFACE. V 



objects, implying that the reader will collect specimens 

 for himself, which is to be strongly recommended as 

 the best method of acquiring a practical and useful 

 acquaintance with the objects. These will serve to 

 furnish permanent landmarks in the great ocean of 

 structural forms, will probably recall in after-years 

 pleasant recollections of early excursions in search 

 of the beauties of nature, and, surely, deepen the 

 conviction of the existence of their All- wise Creator. 



J. W. G. 



