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 Paleontology 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 Paleontology, each formation being consid- 
ered separately, as regards its lithoiogical 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 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 
Paleontology, 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 
