CHAPTER II 



STRATIGRAPHICAL PALAEONTOLOGY 



IT was stated 011 p. 3 that ever since the surface of the earth 

 became a fit habitation for plants and animal life there has been a 

 succession of life-forms, and that remains of these faunas are found 

 as fossils in the stratified rocks. It was also stated that this 

 succession was incomplete owing to gaps in the series. The causes 

 which have produced this imperfection of the record may now be 

 indicated, so that the reader may understand what kinds of creatures 

 are likely to occur as fossils and what are not. It will also be 

 shown that, where the succession is continuous and fossils are fairly 

 abundant, they can be used for the establishment of smaller sub- 

 divisions of the series and for the comparison of such subdivisions 

 in different areas. Finally a few words on the distribution of 

 species at the present day will explain some limitations in the 

 application of palseontological evidence, and the difference between 

 synchronism and homotaxis in correlating the rock - groups of 

 different countries. 



Origin of Species. At the outset of this inquiry we are met 

 by the question, What is a species ? Before the publication of 

 Darwin's book on the Origin of Species most people regarded 

 a species as the result of a special creation of a definite kind of 

 plant or animal, yet all who studied either plants or animals 

 were obliged to admit that some species displayed many varieties, 

 and also that it was difficult to say what amount of difference 

 should constitute a species. 



Lamarck in 1801 was the first to propound the doctrine that 

 all existing species are descended from other species, but few 

 naturalists gave credence to his views, and it was not till 1859, 

 when Darwin published his book, that the world became familiar 

 with such a doctrine. 



On the primary point of the appreciation of differences Darwin 

 remarks (Origin of Species, sixth edition, p. 41), " Certainly no 



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