174 NEW TOKK STATE MUSEUM 



Island and are well represented from Staten Island to the vicin- 

 ity of Camden, New Jersey, are important in the manufacture 

 of pottery. Some of the clay beds contain plant remains and 

 about 50 species of land plants have been recognized here. 

 Among these are many genera which exist at the present day, 

 such as the cinnamon, sassafras, oak, gum etc. The character 

 of this vegetation suggests that a temperate climate prevailed 

 in this region during cretaceous time. A little later, in the Ter- 

 tiary, a sub-tropical climate prevailed in what are now the Arctic 

 regions. West of the Mississippi the Cretaceous deposits of our 

 country are divided into three principal groups; the Dakota, 

 which consists of sandstone and conglomerate with beds of clay; 

 the Colorado, a group of limestone and bituminous shales; and 

 the Laramie, which is a bed of passage into the Tertiary and con- 

 tains important deposits of lignite, a variety of coal. 



Life of the Cretaceous period 

 In the Cretaceous, mammals were still insignificant. The mem- 

 bers of the ammonite group of the cephalopoda, were numerous 

 and varied in form. The other mollusks were closely allied to 

 those of the present day. Many bony fishes appeared and sup- 

 planted the ganoid fishes which had previously prevailed. The 

 reptilian fauna was prominent, but became greatly diminished 

 before the tertiary. With the close of this period occurred a 

 great change in the life of the globe. I 



Cenozoic Time 



Following the close of the Mesozoic age begins the Cenozoic, 

 which includes the Tertiary and Quaternary systems and is char- 

 acterized by a marked resemblance of its life, to that of the 



present day. 



TERTIARY SYSTEM 



Sir Charles Lyell divided the European Tertiary into three 

 parts; the Eocene, Miocene and Pliocene. The Eocene was esti- 

 mated to contain about 10% of living species, the Miocene about 

 50% and the Pliocene about 90%, but these percentages are not of 

 world wide application. 



