OF CREATION. 251 



posits afford information only with regard to the in- 

 habitants of deep water and the open sea, and offer 

 little help in determining the nature of the coast-line. 

 It thus becomes probable that a great part of this 

 difference may, after all, have consisted in a change 

 of the relative level of land and water. However 

 this may be, the group of organic remains in the 

 chalk is not sufficiently perfect to allow of our pic- 

 turing to ourselves any general view of the various 

 races, or obtaining a notion of the characteristic fea- 

 tures of the marine fauna as distinct from those of 

 former and later times. 



On the whole, however, the geological naturalist, 

 recalling the different groups of animals then most 

 abundant, and comparing them with those of more 

 recent and also of more ancient dates, will be struck 

 with many manifest signs of approximation to the 

 existing condition, and may trace a gradual but uni- 

 form advance towards the present forms of life. 



Such general views, forming what is sometimes 

 called the physiognomy of a group of animals or 

 vegetables, are far more important than might be 

 thought at first sight, for they often point distinctly 

 to the truest and most valuable analogies; and, being 

 dependent on the degree of uniformity of the condi- 

 tion under which the inhabitants, whether of land or 

 water, may have existed, they are in themselves real 

 and to be depended on. At the same time, it must 

 be remembered that there are kinds as well as de- 

 grees of analogy, and that resemblance, of whatever 

 kind or degree, by no means involves true affinity 

 or derivation from the same source. So far is this 

 from being the case, that we sometimes, on the con- 



