Vlll 



CONTENTS 



CHAPTER IV 



BRYOZOA (POLYZOA) 



PAGE 



Ectoprocta BUGULA 79 



CHAPTER V 



MOLLUSCA 



Lamellibranchiata A FRESHWATER MUSSEL 83 



A HARD-SHELL CLAM . . 93 



Gastropoda A LAND SNAIL 102 



Cephalopoda A SQUID 113 



CHAPTER VI 



UROCHORDA (TUNICATA) 

 Ascidiacea A SIMPLE ASCIDIAN 125 



CHAPTER VII 



ECHINODERMATA 



Asteroidea A STARFISH 131 



Echinoidea A SEA URCHIN 139 



CHAPTER VIII 



CNIDARIA 

 Hydrozoa HYDRA 145 



A TUBULARIAN HYDROMEDUSAN 149 



A CAMPANULARIAN HYDROMEDUSAN .... 155 



CHAPTER IX 



SPONGIARIA 

 Calcarea GRANTIA ...,, . 161 



