814 SUDDEN APPEARANCE OP 



but that, when this adaptation had once been effected, and a 

 few species had thus acquired a great advantage over other 

 organisms, a comparatively short time would be necessary to 

 produce many divergent forms, which would spread rapidly 

 and widely throughout the world. Professor Pictet, in his 

 excellent review of this work, in commenting on early 

 transitional forms, and taking birds as an illustration, can- 

 not see how the successive modifications of the anterior 

 limbs of a supposed prototype could possibly have been of 

 any advantage. But look at the penguins of the Southern 

 Ocean ; have not these birds their front limbs in this precise 

 intermediate state of " neither true arms nor true wings " 'I 

 Yet these birds hold their place victoriously in the battle for 

 life ; for they exist in infinite numbers and of many kinds. 

 I do not suppose that we here see the real transitional grades 

 through which the wings of birds have passed ; but what 

 special difficulty is there in believing that it might profit the 

 modified descendants of the penguin, first to become enabled 

 to flap along the surface of the sea like the logger-headed 

 duck, and ultimately to rise from its surface and glide 

 through the air ? 



I will now give a few examples to illustrate the foregoing 

 remarks, and to show how liable we are to error in suppos- 

 ing that whole groups of species have suddenly been pro- 

 duced. Even in so short an interval as that between the 

 first and second editions of Pictet's great work on Palaeon- 

 tology, published in 1844-46 and in 1853-57, the conclusions 

 on the first appearance and disappearance of several groups 

 of animals have been considerably 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 hare been discov 

 ered 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 animals, some of 



