148 ZOOLOGY 



Radially symmetrical in adult Phylum Echinodermata. 



Without true coelom. 



With a single mouth, which also functions as an anus: stinging cells 



Phylum Ccslenterata. 

 With numerous incurrent openings or pores, and only one or few 



excurrent. No stinging cells Phylum Porifera. 



Single-celled animals (chiefly) Phylum Protozoa. 



