CONTENTS 



THE CLASS GASTROPODA 382 

 THE CLASS SCAPIIOPODA 387 



TiiF. c:lass ckphaloi'oda 388 



THE MOLLUSK KODN' PLAN 393 



14 SEGMENTED WORMS: THE PHYLUM ANNELIDA 396 



THE CLASS POLYCHAETA 398 



The Clamworm 398 



Other Polychaetes 401 

 THE CLASS OLIGOCHAETA 402 



The Earthworm 402 



Other Oli^ochaetes 416 

 THE CLASS ARCHIANNELIDA 417 

 THE CLASS HIRUDINEA 417 

 THE ANNELID BODY PLAN 420 



15 JOINT-FOOTED ANIMALS AND THEIR KIN: THE PHYLA ARTHROPODA 



AND ONYCHOPHORA 422 



THE PHYLUM ARTHROPODA 422 

 THE CLASS CRUSTACEA 424 



The Crayfish 424 



Other Crustacea 436 

 THE CLASS INSECTA 441 



The Locust 443 



Insect Life Cycles and Metamorphosis 454 



Representative Orders of Insects 457 



Importance of Insects to Man 477 

 THE CLASSES CHILOPODA AND DIPLOPODA 478 

 THE SUBPHYLUM CHELICERATA 480 

 THE PHYLUM ONYCHOPHORA 483 

 THE ARTHROPOD BODY PLAN AND ITS EVOLUTION 484 



16 SPINY-SKINNED ANIMALS: THE PHYLUM ECHINODERMATA 486 



THE CLASS ASTEROIDEA 489 



The Starfish 489 



Other Asteroidea 497 

 THE CLASS OPHIUROIDEA 497 

 THE CLASS ECHINOIDEA 499 



The Sea Urchin 499 



Other Echinoidea 501 

 THE CLASS HOLOTHUROIDEA 503 



The Sea Cucumber 503 



Other Holothuroidea 507 

 THE CLASS CRINOIDEA 507 

 THE ECHINODERM BODY PLAN 508 



