Appendix to Chapter V. 429 



cases are neither few nor unimportant, and therefore they 

 deprive the objection of the force it would have had if the 

 selected cases to the contrar)- were the general rule. 



In addition to these considerations, the following, some of 

 which are of a more special kind, appear to me so important 

 that I will quote them almost in exlenso. 



We continually forget how large the world is, compared with 

 the area over which our geological formations have been care- 

 fully examined : we forget that groups of species may elsewhere 

 have long existed, and have slowly multiplied, before they in- 

 vaded the ancient archipelagoes of Europe and the United States. 

 We do not make due allowance for the intervals of time which 

 have elapsed between our consecutive formations, — longer per- 

 haps in many cases than the time required for the accumulation 

 of each formation. These intervals will have given time for the 

 multiplication of species from some one parent form ; and, in 

 the succeeding formation, such groups of species will appear as 

 if suddenly created. 



I may here recall a remark formerly made, namely, that it 

 might require a long succession of ages, to adapt an organism 

 to some new and peculiar Hne of life, for instance, to fly through 

 the air ; and consequently that the transitional form would often 

 long remain confined to some one region ; but that, when this 

 adaptation had once been effected, and a few species had thus 

 acquired a great advantage over other organisms, a compara- 

 tively short time would be necessary to produce many divergent 

 forms, which would spread rapidly and widely throughout the 

 world. . . . 



In geological treatises, published not many years ago, 

 mammals were always spoken of as having abruptly come in at 

 the commencement of the tertiary series. And now one of the 

 richest known accumulations of fossil mammals belongs to the 

 middle of the secondary series ; and true mammals have been 

 discovered in the new red sandstone at nearly the commence- 

 ment of this great series. Cuvier used to urge that no monkey 

 occurred in any tertiary stratum ; but now extinct species have 

 been discovered in India, South America, and in Europe as far 



