INTRODUCTION. 



PalfT?ontology * deals with the })ayt ()ri;aiiic lite of the 

 earth. It is concerned with the structural characters, the 

 systematic position, the mode of life, and the geographic as 

 well as geologic distribution of former animals and plants. 

 Pakeontology also deals with questions concerning the 

 development of organic forms, and the causes which have 

 determined such develojnnent. 



The data upon which the conclusions of paheontologists 

 are based are derived from the study of fossils and from a 

 comparison of these fossils with living animals and plants. 

 The term Fossil is commonly ap])lied to the remains of 

 animals and plants which were buried before the beginning 

 of the present geologic epoch. t This definition is an arbi- 

 trary one, and is not based on any distinction in character 

 between the remains which were buried before, and those 

 which were buried during, the present geologic ei)och. Thus 

 the marine shells in the post-glacial elevated clays of north- 

 evn New England and Canada differ in nowise from those 

 of the same species buried in the modern deposits off the 

 present coast. In the former case, the strata have been 

 elevated several hundi-ed feet; while in the latter case, they 

 still retain their original position, oi-, at least, have experi- 

 enced no appreciable disturbance. In like manner, many of 

 the Miocene and Pliocene shells ai-e not only of the same 

 species as those recently buried on neighboring shores, but 

 the changes which they have ujidergone, since burial, are 

 frequently not greater than those experienced by shells 

 buried in modern accumulations. The difference in the alter- 

 ation is merely one of degree, and with proper discrimina- 

 tion, specimens can be selected which show all grades of 



* Gr. palaios, ancient ; onta, beings ; logos, discourse. 

 t Zittel — Text-book of Palfeontology. 



