14 CONTENTS 



PAGE 



311; External Anatomy, 313; Internal Anatomy, 314; Metabolism, 

 318; The Nervous System and Nervous Conduction, 319; Reproduction 

 and Life Cycle, 319; Regeneration, 322; Economic Relations of the 

 Phylum, 322; Phylogenetic Advances of Coelenterates, 322. 



CHAPTER XVII 



The Flatworm, Planaria, of Phylum Platyhelminthes _____ 323 

 Classification, 323; Habitat and Behavior of Planaria, 324; External 

 Anatomy, 326; Internal Anatomy, 326; Metabolism, 331; Reproduc- 

 tion and Life History, 331; Regeneration, 333; Economic Relations 

 of the Phylum, 334; Phylogenetic Advances of Platyhelminthes, 334. 



CHAPTER XVIII 



The Roundworm, Ascaris, of Phylum Nemathelminthes _____ 335 

 Classification, 335; Habitat and Behavior of Ascaris, 337; External 

 Anatomy, 338; Internal Anatomy, 339; Reproduction and the Life 

 Cycle, 340; Relations to Man, 341. 



CHAPTER XIX 



Earthworm, of Phylum Annelida (By J. Teague Self) _____ 342 

 Class Chaetopoda, 342; External Anatomy of the Earthworm, 345; 

 Internal Anatomy, 346; Reproductive Organs, 347; Digestive System, 

 348; Circulatory System, 350; Respiratory System, 351; Excretory 

 System, 351; The Nervous System, 352; Reproduction, 352; Regenera- 

 tion, 355; Importance of Annelids to Man and Other Animals, 356; 

 Phylogenetic Advances of Annelida, 357. 



CHAPTER XX 



Starfish, of Phylum Echinodermata, and Other Echinoderms _ _ _ 358 

 Classification, 358; Habitat and Behavior of Starfish, 361; External 

 Anatomy, 363; Internal Anatomy, 363; Reproduction and Life Cycle, 

 368; Regeneration and Autotomy, 370; Economic Relations, 371. 



CHAPTER XXI 



Fresh-Water Mussel and the Snail, of Phylum Mollusca (By Elmer 



P. Cheatum) _________________ 372 



General Characters, 372; Habitat and Behavior of the Clam, 373; 

 External Features, 374; Internal Anatomy, 375; Digestion, 376; 

 Respiration, 376; Circulation, 377; Nervous System and Sense Organs, 

 377; Excretion, 378; Reproduction and Life Cycle, 378; The SnaU, 

 380; Habitat and Behavior, 380; External Anatomy, 383; Internal 

 Morphology, 386; Respiration, 386; Circulation, 387; Nervous System, 

 388; Excretory, 388; Reproduction and Life Cycle, 388; Economic 

 Relations of the Phylum, 391. 



