300 AFFINITIES OF EXTINCT SPECIES. [Chap. XL. 



offer exceptions to the rule. For instance, the species of mastodons 

 and elephants, when arranged hy Dr. Falconer in two series, — in 

 the first place according to their mutual affinities, and in the second 

 place according to their periods of existence, — do not accord in 

 arrangement. The species extreme in character are not the oldest 

 or the most recent ; nor are those which are intermediate in cha- 

 racter, intermediate in age. But supposing for an instant, in this 

 and other such cases, that the record of the first appearance and 

 disappearance of the species was complete, which is far from the 

 case, we have no reason to believe that forms successively produced 

 necessarily endure for corresponding lengths of time. A very 

 ancient form may occasionally have lasted much longer than a form 

 elsewhere subsequently produced, especially in the case of terres- 

 trial productions inhabiting separated districts. To compare small 

 things with great ; if the principal living and extinct races of the 

 domestic pigeon were arranged in serial affinity, this arrangement 

 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 organic remains 

 from an intermediate formation are in some degree intermediate 

 in character, is the fact, insisted on by all paleontologists, that 

 fossils from two consecutive formations are far more closely 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 forma- 

 tion, 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 remem- 

 bered that the forms of life, at least those inhabiting the sea, have 

 changed almost simultaneously throughout the world, and there- 

 fore 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. 



