CONTENTS 11 



PAGE 

 206; Excretory System, 206; The Nervous System, 208; Eeproduction, 

 209; Eegeneration, 212; Importance of Annelids to Man and Other 

 Animals, 215; Phylogenetic Advances of Annelida, 216. 



CHAPTER XVI 



Phylum Echinodermata _______________ 21 7 



Classification, 217; Starfish of Class Asteroidea, 226; Habitat and Be- 

 havior, 226; External Anatomy, 226; Internal Anatomy, 227; Repro- 

 duction and Life Cycle, 234; Regeneration and Autotomy, 234; 

 Economic Relations, 235. 



CHAPTER XVII 



Phylum Mollusca (By Elmer P. Cheatum) _________ 236 



General Characters, 236; The Snail, 237; Habitat and Behavior, 237; 

 External Anatomy, 239; Internal Morphology, 243; Respiration, 244; 

 Circulation, 244 ; Nervous System, 245 ; Excretory, 245 ; Reproduc- 

 tion and Life Cycle, 245; Fresh-Water Clams, 248; Habitat and 

 Behavior, 248; External Features, 249; Internal Anatomy, 250; 

 Digestion, 250; Respiration, 251; Circulation, 252; Nervous System 

 and Sense Organs, 252 ; Excretion, 253 ; Reproduction and Life Cycle, 

 253; Economic Relations of the Phylum, 255; Classification, 256. 



CHAPTER XVIII 

 Phylum Arthropoda ________________ 263 



Classification, 263 ; Crayfish of Class Crustacea, 266 ; Habitat and 

 Behavior, 267; External Structure, 268; Internal Structure, 271; 

 Metabolism, 278; Reproduction, 278; Regeneration and Autotomy, 

 281 ; Economic Relations, 281 ; Characterization of Other Crustacea, 

 282; Recapitulation Theory, 284; Phylogenetic Advances of Arthro- 

 poda, 286. 



CHAPTER XIX 



Phylum Arthropoda (Cont'd) (By Vasco M. Tanner) ______ 287 



Onychophora and Myriapoda, 287; Onychophora, 287; Myriapoda, 

 288. 



CHAPTER XX 



Phylum Arthropoda (Cont'd) (By Vasco M. Tanner) ______ 292 



Arachnida, 292; Spiders, 292; Classification of the Arachnida, 295. 



CHAPTER XXI 



Phylum Arthropoda (Cont'd) (By Vasco M. Taimer) ______ 300 



Class Insecta, 300; Insect Characteristics, 301; Head, 301; Thorax, 

 305; Abdomen, 307; Body Wall, 308; Metamorphosis, 308; Classifica- 

 tion, 309; Hemimetabolous Insects With Incomplete Metamorphosis, 

 320; Holometabolous Insects With Complete Metamorphosis, 321; 

 Other Orders, 333 ; Social Life Among the Insects, 334 ; Guests, 339 ; 



Economic Relations, 340; Useful Insects, 341. 



I 



