CONTENTS xvii 



Page 

 CHAPTER XXXVII 



Fresh- WATER Mussel 212 



External appearance — Shell — Internal anatomy — Body mass and foot — 

 Mantle — Gills — Digestive system and metabolism — Circulatory system — 

 Excretory system — Musculature — Nervous system — Behavior — Reproduc- 

 tion — Other fresh-water mussels. 



CHAPTER XXXVIII 



MoLLusKS IN General 221 



Classification — Amphineura — Gastropoda — Scaphopoda — Pelecypoda — 

 Cephalopoda — Metabolism — Behavior — Reproduction and regeneration — 

 Economic importance. 



CHAPTER XXXIX 



Earthworm ^34 



External characteristics — Internal structure — Alimentary canal and metabo- 

 lism — Circulatory system — Excretory system — Musculature and locomotion 

 — Nervous system — Behavior — Reproduction system and reproduction — 

 Regeneration — Economic importance. 



CHAPTER XL 



Reflex Action 243 



Nervous functions — Reflex acts — Anterior ganglia. 



CHAPTER XLI 



Annelids in General 246 



Classification — Archiannelida — Chaetopoda — Hirudinea — Gephyrea — 

 Metabolism — Behavior — Reproduction — Occurrence and economic impor- 

 tance. 



CHAPTER XLII 



Crayfish 255 



External characteristics — Internal structure — Eyes and vision — Statocyst — 

 Feeding habits — Behavior — Reproduction — Regeneration and autotomy — 

 Economic importance. 



CHAPTER XLIII 

 Crustacea 265 



Malacostraca — Entomostraca — Behavior — Reproduction — Economic impor- 

 tance — Biogenesis. 



CHAPTER XLIV 



Onychophora and Myriapoda 273 



Onychophor a — M y r i a p o d a — Centipedes — Millipedes — Reproduction in 

 myriapods. 



CHAPTER XLV 

 Class Insecta 276 



External characteristics — Internal structures — Senses of insects — Reproduc- 

 tion — Autotomy — Injuries due to insects — Benefits from insects — Injurious 

 types — Combating injurious insects — Beneficial insects — Social insects. 



