OBJECTIONS TO THE THEORY OF DESCENT. 337 



HOW LITTLE WE KNOW OF FOEMEE IKHABITASTTS OF THE 

 WOELD. 



p 283 ETen in so short an interval as that be- 



tween the first and second edition of Pictet's 

 great work on Paleontology, published in 1844-'46 and in 

 1853-57, the conclusions on the first appearance and dis- 

 appearance of several groups of animals have been consid- 

 erably modified ; and a third edition would require still 

 further changes. I may recall the well-known fact that 

 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 commencement 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 back as the 

 Miocene stage. Had it not been for the rare accident of 

 the preservation of footsteps in the new red sandstone of 

 the United States, who would have ventured to suppose 

 that no less than at least thirty different bird-like ani- 

 mals, some of gigantic size, existed during that period ? 

 Not a fragment of bone has been discovered in these beds. 

 Not long ago, paleontologists maintained that the whole 

 class of birds came suddenly into existence during the 

 Eocene period ; but now we know, on the authority of 

 Professor Owen, that a bird certainly lived during the dep- 

 osition of the upper greensand ; and still more recently, 

 that strange bird, the archeopteryx, with a long, lizard- 



* Tektiabt. — ^The latest geological epoch, immediately preceding the 

 establishment of the present order of things. 



