vi PREFACE. 



as a mere department of the great science of Biology. 

 The present work, on the other hand, is an attempt to 

 treat Palaeontology more especially from its historical 

 side, and in its more intimate relations with Geology. 

 In accordance with this object, the introductory por- 

 tion of the work is devoted to a consideration of the 

 general principles of Palaeontology, and the bearings 

 of this science upon various geological problems such 

 as the mode of formation of the sedimentary rocks, 

 the reactions of living beings upon the crust of the 

 earth, and the sequence in time of the fossiliferous for- 

 mations. The second portion of the work deals exclu- 

 sively with Historical Palaeontology, each formation 

 being considered separately, as regards its lithological 

 nature and subdivisions, its relations to other forma- 

 tions, its geographical distribution, its mode of origin, 

 and its characteristic life-forms. 



In the consideration of the characteristic fossils of 

 each successive period, a general account is given of 

 their more important zoological characters and their 

 relations to living forms ; but the technical language of 

 Zoology has been avoided, and the aid of illustrations 

 has been freely called into use. It may therefore be 

 hoped that the work may be found to be available for 

 the purposes of both the Geological and the Zoological 

 student; since it is essentially an outline of Historical 

 Palaeontology, and the student of either of the above- 

 mentioned sciences must perforce possess some knowl- 

 edge of the last. Whilst primarily intended for stu- 

 dents, it may be added that the method of treatment 

 adopted has been so far untechnical as not to render 

 the work useless to the general reader who may desire 

 to acquire some knowledge of the subject of such vast 

 and universal interest. 



In carrying out the object which he has held before 

 him, the Author can hardly expect, from the nature of 



