Invcrtebrata, 



CHAPTER IV. 



SUB-KINGDOM I. PROTOZOA. 



General Characters. The constituent animals 01 this 

 sub-kingdom are animals of extreme simplicity, con- 

 sisting for the most part of un differentiated 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. 



These may be grouped around five typical forms 

 into the following classes. 



FIG. 7. 



Foraminifer, Globigerina bulloides, magnified seventy diameters. 

 This form is found floating in tropical and temperate seas. 



Class 1. Rhizopoda. In the fine white sand on 

 the sea-shore or in the mud of the sea-bottom there are 



