648 THE POPULAR SCIENCE MONTHLY. 



atives of Iguanodon and Megalosaurus of the Old World 3fosasaurns, 

 and many others. Hadrosaurus was herbivorous, while Lcelaps was a 

 carnivore. Both were biped, terrestrial reptiles, thirty feet long, stand- 

 ing fifteen to twenty feet high, and of very peculiar and interesting 

 structure. The former will be remembered as that of which the spirit- 

 ed restoration, made by Prof. Hawkins for the Central Park, was de- 

 stroyed by the order of Judge Hilton. Mosasaurus was a snake-like, 

 marine lizard, some sixty or seventy feet long, and of pronounced car- 

 nivorous habits. These, with their associates, probably densely popu- 

 lated the land and sea, while the air was the special domain of the 

 huge flying dragons the pterodactyls. With such a numerous and 

 so enterprising a population, it is evident that life in this time and 

 region was full of variety. 



At the close of the Cretaceous age the animal life, both sea and land, 

 was again revolutionized, but by causes which we cannot yet fully un- 

 derstand, as the physical conditions remain nearly the same, and the flora 

 suffered little change. The facts, however, are unquestionable. All 

 the great reptilian fauna disappeared as if by magic, and gave place to 

 herds of mammals, numerous and large it is true, but far inferior in size 

 and armament to their predecessors. In the sea, the whole Ammonite 

 family disappeared at once, and other great changes took place, so that 

 in the upper or Tertiary bed of green-sand, deposited in the same place 

 and under nearly the same conditions as the lower and Cretaceous two, 

 but tee knoic not how many thousands of years after, not a single one 

 of all the species of Cretaceous mollusks, radiates, or marine vertebrates, 

 mingled its remains with those of the new-comers. 



'to' 



II. New York in the Ice Period. The excavation of New York 

 Harbor and the trough of the Hudson seems to have been effected in 

 late Tertiary times. During the first portion of the Tertiary age the 

 Eocene the coast from New York southward was low, and the sea 

 washed the base of the Alleghany Mountains, covering the coast-plain 

 and depositing upon it the uppermost and most recent of the marl-beds 

 of New Jersey. But in the middle and later Tertiary epochs the 

 Miocene and Pliocene all the northern portion of the continent stood 

 higher above the sea than now, for we find there no marine deposits of 

 that age; and the immense numbers of fiords, or submerged valleys 

 which fringe the coast, are, as Dana long since pointed out, the results 

 of subaerial erosion and proofs of elevation. A genial climate then 

 prevailed to the Arctic Sea, and all the continent was covered with a 

 more luxuriant flora, and inhabited by a more varied fauna, than can 

 now be found anywhere on its surface. 



This was, indeed, for America, the golden age of animals and plants, 

 and in all respects but one the absence of man the country was more 

 interesting and picturesque than now. We must imagine, therefore, 

 that the hills and valleys about the present site of New York were 



