APPENDIX A 



CLASSIFICATION OF THE CHIEF ANIMAL PHYLA 



Grade PROTOZOA. The body consists of a single cell, or of a 



few cells not differentiated to form tissues. 

 Grade METAZOA. The body consists of numerous cells aggre- 

 gated together to form tissues. 

 Phylum COELENTERATA. The body consists of two primary 



layers, the ectoderm and endoderm (diploblastic). Instances 



Jelly-fish, Anemones, Corals, etc. 

 Phylum PLATYHELMIA. The body consists of three primary 



layers, ectoderm, endoderm and mesoderm (triploblastic) ; 



no vascular system or perivisceral coelom. Body flattened 



dorso - ventrally. Instances Turbellarians, Liver - flukes, 



Tape-worms, etc. 

 Phylum NEMATODA. Triploblastic animals, without vascular 



system or perivisceral coelom. Body round. Instances 



Ascaris, Rhabditis, etc. 

 Phylum NEMERTEA. Triploblastic animals with vascular 



system but no perivisceral coelom. Body round. Instances 



Cerebratulus, etc. 

 Phylum APPENDICULATA. Triploblastic animals with vascular 



system and typically a perivisceral coelom which may be 



secondarily reduced. Body usually metamerically segmented. 



Nervous system ventral. 



Series Annelida. Marine, fresh-water or land worms with 

 segmented bodies. 



