Chap. X. AFFINITIES OF EXTINCT SPECIES. 335 



supposing for an instant, in this and other such cases, 

 that the record of the first appearance and disappearance 

 of the species was perfect, we have no reason to believe 

 that forms successively produced necessarily endure for 

 corresponding lengths of time : a very ancient form 

 might occasionally last much longer than a form else- 

 where subsequently produced, especially in the case of 

 terrestrial productions inhabiting separated districts. 

 To compare small things with great: if the principal 

 living and extinct races of the domestic pigeon were 

 arranged as well as they could be in serial affinity, this 

 arrangement would not closely accord with the order in 

 time of their production, and still less with the order of 

 their disappearance ; for the parent rock-pigeon now 

 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 same 

 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, 

 insisted 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 

 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 

 firm 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 the distinct species in closely consecutive 



