GENERAL ORGANIZATION OF THE ANIMAL BODY 245 



to one or another of the following types : the protozoan or unicel- 

 lular type, which occurs only in the Phylum Protozoa; the para- 



A 





Fundamental Types \ Enterocoela 



Mollusca 



Fig. 118. — Principal types of animal structure and their probable relationships 



for comparison with Fig. 117. 



zoan type, found only in the Phylum Porifera or sponges (Fig. 118), 

 and differing from that of other many-celled animals principally in 



