PREFACE. 



A HE study of extraneous fossils is confessedly 

 useful to the Geologist it enables him to distin- 

 guish the relative ages of the various strata,, which 

 compose the surface of our globe ; and to explain, 

 in some degree, the processes of nature, in the 

 formation of the mineral world To the Botanist 

 and Zoologist, an investigation, which leads to the 

 knowledge of organic forms no longer found in 

 a recent state, must always prove interesting 

 And the causes, that have operated to produce the 

 distinctions existing between plants and animals of 

 the present day, and those of former unknown ages, 

 offer, to every contemplative mind, an inexhaust- 

 able source of rational enquiry. 



In an age, therefore, like ours, when Natural 

 History in general is cultivated with so much ardour, 

 and introductory helps to its scientific attainment 



