2 o8 THE POPULAR SCIENCE MONTHLY. 



computation, cannot be placed at less than 3,000 or 4,000 years before 

 the time at which they were thus brought to light. Cuvier endeav- 

 ored to ascertain, by a very just and proper method, what foundation 

 there was for the belief in a gradual and progressive change of ani- 

 mals, by comparing the skeletons and all accessible parts of these 

 animals, such as crocodiles, birds, dogs, cats, and the like, with those 

 which are now found living in Egypt, and he came to the conclusion 

 a conclusion which has been verified by all subsequent research 

 that no appreciable change had taken place in the animals which 

 inhabited Egypt. And he drew thence the conclusion, and a hasty 

 one, that this fact was altogether opposed to the doctrine of evolu- 

 tion. The progress of research since Cuvier's time has furnished far 

 stronger arguments than those which he drew from the mummified 

 bodies of Egyptian animals. A remarkable case is to be found in 

 your own country in the neighborhood of the magnificent falls of 

 Niagara. In the immediate vicinity of the whirlpool, and again upon 

 Goat Island, in the superficial deposits which cover the surface of the 

 soil of the rock in those regions, there are found remains of animals 

 in perfect preservation shells belonging to exactly the same forms 

 as at present inhabit the still waters of Lake Erie. It is evident from 

 the formation of the country that these animal remains were deposited 

 in the beds in which they occur, at the time at which the lake extended 

 over the region in which they are found. This involves the necessity 

 that they lived and died before the falls had cut their w T ay back 

 through the gorge of Niagara ; and, indeed, it is possible to deter- 

 mine that at that time the falls of Niagara must have been at least six 

 miles farther down the river than they are at present. Many compu- 

 tations have been made of the rate at which Niagara is thus cutting 

 its way back. Those computations have varied greatly, but I believe 

 I am speaking within the bounds of prudence if I assume that the 

 tails of Niagara have not retreated at a greater pace than about a foot 

 a year. Six miles, speaking roughly, are 30,000 feet ; 30,000 feet, at 

 a foot a year, are 30,000 years ; and we are fairly justified in conclud- 

 ing that no less a period than this has passed since these shell-fish, 

 whose remains are left in the beds to which we have referred, were 

 deposited. But there is even still stronger evidence of the long dura- 

 tion of certain types than this. As we work our way through the 

 great series of the Tertiary formations, we find species of animals iden- 

 tical with those which live at the present day, diminishing in num- 

 bers, it is true, but still existing in a certain number in the oldest of 

 the Tertiary rocks. And not only so, but when we examine the rocks 

 of the Cretaceous epoch itself, we find the remains of some animals 

 which the closest scrutiny cannot show to be in any respect different 

 from those which live at the present time. That is the case with one 

 of the lamp-shells, a Terebratula which is found in the chalk, and 

 which has continued as it was found, or with insignificant variation, 



