VI PREFACE. 



Paleontology regarded in its strictly scientific aspect, 



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 portion 

 of the work is devoted to a consideration of the general 

 principles of Paleontology, and the bearings of this 

 science upon various geological problems — such as the 

 mode of formation of the sedimentary rocks, the reac- 

 tions of living beings upon the crust of the earth, and 

 the sequence in time of the fossiliferous formations. 

 The second portion of the work deals exclusively with 

 Historical Palaeontology, each formation being consid- 

 ered separately, as regards its lithological nature and 

 subdivisions, its relations to other formations, its geo- 

 graphical distribution, its mode of origin, and its char- 

 acteristic 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 ma}^ 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 know- 

 ledge 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 



