CONTENTS 



Preface ix 



Acknowledgments xi 



A Memorial to Frank Collins Baker (1867-1942) .... xvii 

 A Chronological List of the Scientific Publications 



OF Frank Collins Baker xxv 



Original Articles and Books xxv 



Biographical Contributions xxxv 



Book Notices and Reviews xxxv 



PART I 



Classification and General ^Morphology 



I. General ^Morphology 3 



A. External Appearance of the Animal 3 



B. General Internal Anatomy 4 



(a) The Reproductive System 4 



(b) The Digestive System 9 



(1) The Jaw 10 



(2) The Radiila 11 



(c) The Renal System 12 



(d) The Circulatory System 13 



(e) The Respiratory System 14 



(f) The Nervous System 14 



(g) The [Muscular System 15 



C. The Shell 15 



II. General Ecology 17 



General Environmental Conditions 17 



Variations in Different Environments 18 



Locomotion 19 



Food 19 



Food for Other Animals 19 



Length of Life 20 



The Planorbidae as Hosts for Parasitic Worms 21 



III. XlDIFICATION AND EmBRYOLOGICAL DEVELOPMENT .... 25 



A. Development of Helisoma scolare (Jay) 25 



B. Nidification and Development in Other Species of Helisoma 28 



(a) Self-fertilization or Autofecundation 29 



(b) The Development of Helisoma 31 



(1) Helisoma trivolvis lentum (Say) 31 



(2) Helisoma trivolvis fallax (Haldeman) 32 



(3) Helisoma duryi nor male Pilsbry 33 



(4) Helisoma duryi eudiscus Pilsbry 34 



(5) Helisoma tenue calif orniense F. C. Baker .... 34 



(6) Other Records of Egg Laying 35 



Xlll 



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