178 LAY SERMONS, ESSAYS, AND REVIEWS. [x. 



Cuvier) a subordinate branch of biology should have doubled the 

 value and the interest of the whole group of sciences to which 

 it belongs. 



But this is not all. Allied with geology, palaeontology has 

 established two laws of inestimable importance : the first, that 

 one and the same area of the earth s surface has been suc 

 cessively occupied by very different kinds of living beings ; the 

 second, that the order of succession established in one locality 

 holds good, approximately, in all. 



. The first of these laws is universal and irreversible ; the second 

 is an induction from a vast number of observations, though it 

 may possibly, and even probably, have to admit of exceptions. 

 As a consequence of the second law, it follows that a peculiar 

 relation frequently subsists between series of strata, containing 

 organic remains, in different localities. The series resemble 

 one another, not only in virtue of a general resemblance of the 

 organic remains in the two, but also in virtue of a resemblance 

 in the order and character of the serial succession in each. 

 There is a resemblance of arrangement; so that the separate 

 terms of each series, as well as the whole series, exhibit a 

 correspondence. 



Succession implies time ; the lower members of a series of 

 sedimentary rocks are certainly older than the upper ; and when 

 the notion of age was once introduced as the equivalent of suc 

 cession, it was no wonder that correspondence in succession 

 came to be looked upon as a correspondence in age, or &quot; contem 

 poraneity.&quot; And, indeed, so long as relative age only is spoken 

 of, correspondence in succession is correspondence in age ; it is 

 relative contemporaneity. 



But it would have been very much better for geology if so 

 loose and ambiguous a word as &quot; contemporaneous &quot; had been 

 excluded from her terminology, and if, in its stead, some term 

 expressing similarity of serial relation, and excluding the notion 

 of time altogether, had been employed to denote correspondence 

 in position in two or more series of strata. 



