PREFACE. 



HAVING discovered that the Region formerly inhabited by the Silures, 

 celebrated in our annals for the defence of the great Caractacus, contained 

 a vast and regular succession of undescribed deposits of a remote age, I 

 have named them the " Silurian System 1 ". 



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The Introductory Chapter details the state of the subject when this in- 

 quiry commenced, the origin and progress of the work, and the objects to 

 be attained by its completion. 



The first part, embracing descriptive geology, concludes with a review 

 of the most striking phenomena of the ancient epochs which I seek to 

 illustrate ; the second describes the fossil animals which are imbedded in 

 the strata. The map, coloured sections, and numerous wood-cuts, mark 



1 See a notice of the ancient topography of the Silurian Region, p. xxxi. 



