INTEODUCTOEY. 



Secondly : a history of tlie steps whicli led to tlie 

 discovery and proper interpretation of this ancient 

 fossil. Thirdly : the description of Eozoon, and the 

 explanation of the manner in which its remains have 

 been preserved. Fourthly: inquiries as to forms of 

 animal life, its contemporaries and immediate succes- 

 sors, or allied to it by zoological affinity. Fifthly: 

 the objections which have been urged against its 

 organic nature. And sixthly : the summing up of the 

 lessons in science which it is fitted to teach. On these 

 points, while I shall endeavour to state the substance 

 of all that has been previously published^ I shall bring 

 forward many new facts illustrative of points hitherto 

 more or less obscure, and shall endeavour so to picture 

 these in themselves and their relations, as to give 

 distinct and vivid impressions to the reader. 



For the benefit of those who may not have access to 

 the original memoirs, or may not have time to consult 

 them, I shall append to the several chapters some of 

 the technical details. These may be omitted by the 

 general reader ; but will serve to make the work more 

 complete and useful as a book of reference. 



The only preparation necessary for the unscientific 

 reader of this work, will be some little knowledge of 

 the division of geological time into successive ages, 

 as represented by the diagram of formations appended 

 to this chapter, and more full explanations may be 

 obtained by consulting any of the numerous element- 

 ary manuals on geology, or ^^ The Story of the Earth 

 and Man,^^ by the writer of the present work. 



