114 AFFINITIES OP EXTINCT SPECIES. [Chap. XI. 



ter, intermediate in age. But supposing for an instant, 

 in this and other such eases, that the record of the first 

 appearance and disappearance of the species was com- 

 plete, which is far from the case, we have no reason to 

 believe that forms successively produced necessarily en- 

 dure for corresponding lengths of time. A very an- 

 cient form may occasionally have lasted much longer 

 than a form elsewhere subsequently produced, especially 

 in the case of terrestrial productions inhabiting sepa- 

 rated districts. To compare small things with great; 

 if the principal living and extinct races of the domestic 

 pigeon were arranged in serial affinity, this arrange- 

 ment would not closely accord with the order in time 

 of their production, and even less with the order of 

 their disappearance; for the parent rock-pigeon still 

 lives; and many varieties between 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 tumblers, which 

 are at the opposite end of the series in this respect. 



Closely connected with the statement, that the or- 

 ganic remains from an intermediate formation are in 

 some degree intermediate in character, is the fact, in- 

 sisted on by all palaeontologists, that fossils from two 

 consecutive formations are far more closely related to 

 each other, than are the fossils from two remote forma- 

 tions. Pictet gives as a well-known instance, the gen- 

 eral resemblance of the organic remains from the sev- 

 eral 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 ac- 

 quainted with the distribution of existing species over 



