18 



Invtrtebrata. 



CHAPTER IV. 



SUB-KINGDOM 



PROTOZOA. 



General Characters. The constituent animals of this 

 sub-kingdom are animals of extreme simplicity, con- 

 sisting for the most part of undifferentiated protoplasm. 

 None of them possess a nervous system, sense organs, 

 nor a body cavity, nor do we find differentiated organs 

 present in any of them. 



Among these there are five chief types forming five 

 classes. 



FIG. 7. 



One of the minute Foraminifera, Globige* ina bulloides, magnified 

 seven; y diameters. 



Certain forms, called Monera, are even simpler 

 than the Rhizopods, as they not only want the power 



