Basis of classification (brief account)-:
Locomotion
Nutrition and digestion
Respiration
Mechanism of respiration
Excretion
Trends in Neural Evolution
and Mollusca (Cephalopoda)
Invertebrate larvae
Significance of larval forms
Minor Phyla (Ctenophora,Rhyncocoela,Entoprocta,Rotifera,Bryozoa,Phoronida)
Organization and general characters