16 PREFACE. 



characters, can at best only be surmised. When fossils are so 

 indefinite as these, it is exceedingly diflBcult to see their im- 

 portance to geology, and further than indicating the possible 

 presence of other genera in particular strata, or furnishing a 

 clae to the probable occurrence of other forms when the 

 morphological characters of a previously unknown individual 

 cannot be made out, it certainly must have small value in 

 geologic work. Ancient forms of life subserve two great ends : 

 the one phylogenetic ; the other stratigraphic. The first is 

 purely biological in its bearings, and contributes to a better 

 understanding of the great plan of life. The second is geolo- 

 gical in its aims, and is of the utmost importance in the con- 

 sideration of the broad faunal questions pertaining to correla- 

 tion. Both require a more or less complete knowledge of the 

 structural features of species before the fossils perform their 

 highest functions. The value of a form, therefore, is propor- 

 tional to the perfection of preservation and the correct inter- 

 pretation of its anatomical nature. 



The morphological facts already brought out by the inves- 

 tigation of fossil organisms is only suggestive of the vast and 

 fertile field open to the student who directs his energies along 

 this line. Thus intimately connected with biology, the re- 

 sults of the study of the material accumulated up to the pres- 

 ent time cannot but give most valuable aid in making out the 

 phylogenetic history of the living zoological groups. Indeed, 

 the importance of this consideration cannot be overestimated 

 in the attempt toward an understanding of a complete phylogeny 

 of organic beings. Viewed from an anatomical and embryo- 

 logical standpoint, the dead become rejuvenated ; the '"curious 

 stones " live ; the rocks disclose the great plan of life. More 

 lasting, more useful, more worthy of contemplation, are pale- 

 ontological labors directed thus, rather than to the indiscrimi- 

 nate multiplication of species, to the mere description of 

 curiosities. 



Not less important is the recognition of the mutual de- 

 pendence of paleontology and stratigraphy for the attainment 

 of the highest and most accurate results in generalizations. 



