72 SELECTIONS FROM HUXLEY 



Certainly not one of the higher animals was of the same species 

 as any of those now in existence. The beasts of the field, in 

 the days before the chalk, were not our beasts of the field, nor 

 the fowls of the air such as those which the eye of man has seen 

 5 flying, unless his antiquity dates infinitely further back than 

 we at present surmise. If we could be carried back into those 

 times, we should be as one suddenly set down in Australia 

 before it was colonized. We should see mammals, birds, 

 reptiles, fishes, insects, snails, and the like, clearly recognizable 



10 as such, and yet not one of them would be just the same as 

 those with which we are familiar, and many would be ex- 

 tremely different. 



From that time to the present, the population of the world 

 has undergone slow and gradual, but incessant, changes. 



15 There has been no grand catastrophe no destroyer has 

 swept away the forms of life of one period, and replaced them 

 by a totally new creation ; but one species has vanished and 

 another has taken its place ; creatures of one type of structure 

 have diminished, those of another have increased, as time has 



20 passed on. And thus, while the differences between the living 

 creatures of the time before the chalk and those of the pres- 

 ent day appear startling, if placed side by side, we are led 

 from one to the* other by the most gradual progress, if 

 we follow the course of Nature through the whole series of 



25 those relics of her operations which she has left behind. 



And it is by the population of the chalk sea that the ancient 

 and the modern inhabitants of the world are most com- 

 pletely connected. The groups which are dying out flourish, 

 side by side, with the groups which are now the dominant 



30 forms of life. 



Thus the chalk contains remains of those strange flying 

 and swimming reptiles, the pterodactyl, the ichthyosaurus, 

 and the plesiosaurus, which are found in no later deposits, 

 but abounded in preceding ages. The chambered shells called 



