PREFACE. 



THE study of Palaeontology, or the science which is 

 concerned with the living beings which flourished upon 

 the globe during past periods of its history, may be 

 pursued by two parallel but essentially distinct paths. 

 By the one method of inquiry, we may study the 

 anatomical characters and structure of the innumerable 

 extinct forms of life which lie buried in the rocks 

 simply as so many organisms, with but a slight and 

 secondary reference to the time at which they lived. 

 By the other method, fossil animals are regarded prin- 

 cipally as so many landmarks in the ancient records of 

 the world, and are studied historically and as regards 

 their relations to the chronological succession of the 

 strata in which they are entombed. In so doing, it is 

 of course impossible to wholly ignore their structural 

 characters, and their relationships with animals now 

 living upon the earth ; but these points are held to 

 occupy a subordinate place, and to require nothing 

 more than a comparatively general attention. 



In a former work, the Author has endeavoured to 

 furnish a summary of the more important facts of 



