CONTENTS. 



Page. 

 Intkoduction. 



1. Distribution of Species • . 1 



2. Migration 2 



3. Longevity and Rate of Growth 2 



4. Food 2 



5. Economic Value 3 



6. Review of Previous Work 3 



Anatomy. 



1. Orientation 4 



2. General Anatomy 4 



3. The Skin 9 



4. The Skeleton 13 



a. Exoskeleton 13 



b. Endoskeleton ..." 14 



5. The Skull or Cephalic cartilages 14 



6. The Muscular System 16 



a. Mantle and Fins 16 



b. Foot 19 



Arms, Hectocotylus . . . . \ . . 19 



Siphon 23 



c. Muscles of the Visceral Mass 24 



7. The Head .26 



8. The Pallia] Chamber, Viscera, and Pallial Complex 27 



9. The Alimentary Canal. 29 



a. General Form 29 



b. Pharynx, Jaws, Muscles, Radula and Glands . 29 



c. Oesophagus .35 



d. Stomach 35 



e. Caecum, Liver and Pancreas 36 



f. Intestine, Rectum, and Ink Sac 41 



10. The Reproductive System 44 



a. Male 45 



b. Female 51 



11. The Circulatory System . 54 



a. Systemic Circulation; Nephridium ..." 55 



b. Respiratory Circulation , Gill 63 



c. Blood glands, Branchial gland and White Bodies 66 



12. The Body Cavities 66 



13. The Nervous System 67 



14. The Sense Organs 77 



a. Statocysts . . . ■ . . 78 



b. Eye 80 



15. Bibliography 89 



