Vlll 



CONTENTS 



Ectoprocta 



CHAPTER IV 

 BRYOZOA (POLYZOA) 



BUGULA 



PAGE 



85 



CHAPTER V 



MOLLUSCA 



Pelecypoda A Freshwater Mussel 89 



An Oyster 99 



A Hard-Shell Clam 103 



Gastropoda A Land Snail 112 



Cephalopoda A Squid 123 



Ascidiacea 



CHAPTER VI 

 TUNICATA 

 A Simple Ascidian . . . 



135 



CHAPTER VII 

 ECHINODERMATA 



Asteroidea A Starfish 141 



Echinoidea A Sea Urchin 149 



Holothurioidea A Holothurian 155 



CHAPTER VIII 

 CNIDAPJA 



Hydrozoa Hydra 159 



A Tubularian Hydromedusan 163 



A Campanularian Hydromedusan 169 



Gonionemus 175 



Anthozoa A. Sea Anemone 178 



