Appendix to Chapter V. 427 



However, be this as it may, I will now pass on to con- 

 sider the difficulties and objections which have been brought 

 against the theory on grounds of palaeontology. 



These may be classified under four heads. First, the ab- 

 sence of varietal links between allied species ; second, the 

 sudden appearance of whole groups of species — not only as 

 genera and families, but even sometimes as orders and classes 

 — without any forms leading up to them ; third, the occurrence 

 of highly organized types at much lower levels of geological 

 strata than an evolutionist would antecedently expect ; and, 

 fourth, the absence of fossils of any kind lower down than 

 the Cambrian strata. 



Now all these objections depend on est'mates of the im- 

 perfection of the ^-eological record much lower than that 

 which is formed by Darwin. Therefore 1 have arranged the 

 objections in their order of difficulty in this respect, or in the 

 order that requires successively increasing estimates of the 

 imperfection of the record, if they are to be successively 

 answeied. 



I think that the first of them has been already answered in 

 the text, by showing that even a very moderate estimate of the 

 imperfection of the record is enough to explain why interme- 

 diate varieties, connecting allied species, are but comparatively 

 seldom met with. Moreover it was shown that in some cases, 

 where shells are concerned, remarkably well-connected series 

 of such varieties have been met with. And the same applies 

 to species and genera in certain other cases, as in the 

 equine family. 



But no doubt a greater difficulty arises where whole groups 

 of species and genera, or even families and orders, appear to 

 arise suddenly, without anything leading up to them. Even 

 this the second difficulty, however, admits of being fully met, 

 when we remember that in very many cases it has been 

 proved, quite apart from the theory of descent, that super- 

 jacent formations have been separated from one another by 



