TERTIARY FOSSILS. 95 



lopment of nature's kingdom, nearer and nearer 

 to living types. But it is not a development after 

 our author's scheme. It follows the law of the 

 rise, progress, and decline of the families of the 

 older world, already pointed out. We have no 

 confusion of genera and species, and no shades of 

 structure to make dim their outlines." Now there 

 is here an acknowledgment, in which all geologists 

 accord, of a constant gradual approach to living 

 types. Is not this, in itself, a fact speaking strongly 

 ' for some simply natural procedure in the origin 

 of the present tribes ? A change goes on from one 

 set of forms to another, in the same way as one 

 human generation is changed for another — namely, 

 by the withdrawal of some and the addition of 

 others, until at length the whole personnel of one 

 age is superseded by that of another. The re- 

 moval of old species is the result, by our critic's 

 own showing, of law ; and laws for the extinction 

 of species are in operation at the present day. 

 Can we well suppose the rise of the new species 

 to be a phenomenon of an essentially different 

 character ? for here is the whole question at issue. 

 I say, no — any ideas I have ever acquired of philo- 

 sophy, as an expression of oiu- ascertainment of 

 the order of nature or providence, forbid me to 



