THE CRETACEOUS PERIOD. 



271 



Mesozoic deposits, we have now an astonishingly large number 

 of true Angiospermous Exogens, many of them belonging to 

 existing types; and along with these are various Monocotyle- 

 donous plants, including the first examples of the great and im- 

 portant group of the Palms. It is thus a matter of interest to 

 reflect that plants closely related to those now inhabiting the 

 earth, were in existence at a time when the ocean was tenanted 

 by Ammonites and Belemnites, and when land and sea and 

 air were peopled by the extraordinary extinct Reptiles of the 

 Mesozoic period. 



As regards animal life, the Protozoans of the Cretaceous 

 period are exceedingly numerous, and are represented by Fora- 



?. 186. Cretaceous Angiosperms. a. Sassafras Cretaceum; b, Liriodendron 

 Meekii; c, Leguminositea Marcouanus; d, Salix Meekii. (After Dana.) 



minifera and Sponges. As we have already seen, the White 

 Chalk itself is a deep-sea deposit, almost entirely composed 

 of the microscopic shells of Foraminifers, along with Sponge- 

 spicules, and organic debris of different kinds (see p. 23, fig. 7). 

 The green grains which are abundant in several minor sub- 



