423 On American Geological History. 



the successor to the huge Mastodon, Elephant, and the Boothe- 

 rium ; the small Beaver to the great Castoroides ; and the exist- 

 ing Carnivora are all comparatively small. 



Parallel with this fact, we find that in South America, as Dr. 

 Lund observes, where, in the last age before Man, there were the 

 giant Megatherium and Giyptodon, and other related Edentates, 

 there are now the small Sloths, Armadillos, and Anteaters. 



So, also, on the Oriental continent, the gigantic Lion, Tiger, 

 Hyena, and Elephant, and other monster quadrupeds, have now 

 their very interior representatives. 



Li New Holland, too, the land of Marsupials, there are Mar- 

 supials still, but of less magnitude. 



2. This American continent has contributed to science a know- 

 edge^of some of the earliest traces of Reptiles, — the species of the 

 Pennsylvania coal formation, described by Mr. King and Mr. 

 Lea, and others from the Nova Scotia coal-fields, discovered by 

 Messrs. Dawson and Lyell. 



It has afforded the earliest traces of birds thus far deciphered in 

 geological history, — the colossal and smaller waders, whose tracks 

 cover the clayey layers and sandstone of the Jurassic rocks in 

 the Connecticut valley. The earliest Cetacea yet known are from 

 he American Cretaceous beds, as described by Dr. Leidly. And 

 among the large Mammals which had had posession of the renew- 

 ed world after the Cretaceous life had been swept away, the 

 largest, as far as has been ascertained, lived on this continent. 

 The Palcnsotheria of the Paris Basin, described by Cuvier, were 

 but half the size of the allied Titanotheria of Nebraska. 



But here our boasting ceases, for, as Agassiz has shown, the 

 present Fauna of America is more analogous to the later Ter- 

 tiary of Europe than to the existing species of that continent. 



In the PaljBOzoic Ages,to theclose of the Coal Period, the Ameri- 

 cancontinent was as brilliant and perhaps as profuse in its life as any 

 other part of the world. It was a period, indeed, when the globe 

 was in g,n important sense a unit, not individualized in its cli- 

 mates or its distribution of life, and only partially in its seas. But 

 from this time the contrast is most strikinor. 



The whole number of known American species of animals of the 

 Permia.n,Triassic, JurassicCretaceous,and Tertiary Periods is about 

 two thousand ; while in Britain and Europe, a territory even 

 smaller, there were over twenty thousand species. In the Per 

 mian we have none, while Europe has over two hundred species. 



