GEOLOGICAL SUCCESSION 309 



of character, why the more ancient a form is, the more 

 it generally differs from those now living. Why ancient 

 and extinct forms often tend to fill up gaps between 

 existing forms, sometimes blending two groups pre- 

 viously classed as distinct into one ; but more commonly 

 only bringing them a little closer together. The more 

 ancient a form is, the more often, apparently, it dis- 

 plays characters in some degree intermediate between 

 groups now distinct ; for the more ancient a form is, 

 the more nearly it will be related to, and consequently 

 resemble, the common progenitor of groups, since be- 

 come widely divergent. Extinct forms are seldom 

 directly intermediate between existing forms ; but are 

 intermediate only by a long and circuitous course 

 through many extinct and very different forms. We 

 can clearly see why the organic remains of closely 

 consecutive formations are more closely allied 

 to each other, than are those of remote formations ; 

 for the forms are more closely linked together 

 by generation : we can clearly see why the remains 

 of an intermediate formation are intermediate in 

 character. 



The inhabitants of each successive period in the 

 world's history have beaten their predecessors in the 

 race for life, and are, in so far, higher in the scale of 

 nature ; and this may account for that vague yet ill- 

 defined sentiment, felt by many palaeontologists, that 

 organisation on the whole has progressed. If it should 

 hereafter be proved that ancient animals resemble 

 to a certain extent the embryos of more recent 

 animals of the same class, the fact will be intelligible. 

 The succession of the same types of structure within 

 the same areas during the later geological periods 

 ceases to be mysterious, and is simply explained by 

 inheritance. 



If then the geological record be as imperfect as I 

 believe it to be, and it may at least be asserted that 

 the record cannot be proved to be much more perfect, 

 the main objections to the theory of natural selection 

 are greatly diminished or disappear. On the other 



