122 THE ORIGIN OF SPECIES 



the rock-pigeon and the carrier have become extinct; and 

 carriers which are extreme in the important character of 

 length of beak originated earlier than short-beaked tum- 

 blers, which are at the opposite end of the series in this 

 respect. 



Closely connected with the statement that the organic 

 remains from an intermediate formation are in some de- 

 gree intermediate in character, is the fact, insisted on by 

 all paleontologists, that fossils from two consecutive for- 

 mations are far more closel}^ related to each other, than 

 are the fossils from two remote formations. Pictet gives, 

 as a well-known instance, the general resemblance of the 

 organic remains from the several stages of the Chalk 

 formation, though the species are distinct in each stage. 

 This fact alone, from its generality, seems to have shaken 

 Professor Pictet in his belief in the immutability of 

 species. He who is acquainted with the distribution 

 of existing species over the globe will not attempt to 

 account for the close resemblance of distinct species in 

 closely consecutive formations, by the physical conditions 

 of the ancient areas having remained nearly the same. 

 Let it be remembered that the forms of life, at least 

 those inhabiting the sea, have changed almost simul- 

 taneously throughout the world, and therefore under 

 the most different climates and conditions. Consider the 

 prodigious vicissitudes of climate during the pleistocene 

 period, which includes the whole glacial epoch, and note 

 how little the specific forms of the inhabitants of the sea 

 have been affected. 



On the theory of descent, the full meaning of the 

 fossil remains from closely consecutive formations being 

 closely related though ranked as distinct species is ob- 



