28 



Gastr.ea. 

 (Primitive intestinal cavity.) 



ACOELOMI. 



(Bloodless Worms.) 



CcELOiMATI. 



(Worms with blood.) 



SpongEc, Acalepha:. Zoophyta 2 



Vermes 3- 



Mollusca 4 



Echinodermata 5 



Arthropoda 6 



Vertebrata 7 



