page 



XXXVII Plankton coniinunitics o{ S. sctosa and S. clcgaiis I43 



XXXVIII Zooplankton I47 



XXXIX Oceanic plankton 148 



XL Echo sounder: echo trace I59 



LIST OF TEXT FIGURES 



page 



1 . Victor Hensen 4 



2. H.M.S. Challenger 6 



3. Types of nets 12 



4. Types of nets 13 



5. The 'Hardy' Plankton Indicator 19 



6. The 'Hardy' Continuous Recorder 22 



7. Nanoplankton 29 



8. Division of a diatom 31 



9. Piiiniilaria showing raphe 34 



10. Gyniiiodiniuni vcncficiiiDi 37 



11. Coccolithophorcs 41 



12. Protozoa 44 



13. Small jellyfish 49 



14. More small jellyfish 5° 



15. Nematocysts 51 



16. Large jellyfish 52 



17. Other coelcnterates etc ■ 56 



18. Various kinds of zooplankton 64 



19. Planktonic Crustacea 69 



20. Copepods 71 



21. Crustacean larvae etc 73 



22. Crustaceans 75 



23. Tunicata 78 



24. Planktonic larvae of invertebrates 84 



25. Planktonic stages of polychaete worms 86 



26. Echinoderm larvae etc. 90 



27. Fish eggs 96 



28. Surface currents in the North Atlantic 109 



29. Seasonal variation of plankton in polar, temperate and tropical zones 1 1 1 



30. Abundance of plankton in the North Atlantic 114 



3 1 . The food cycle in the sea 121 



32. The economy of the sea 126 



33. Fluctuations in year class strength ot haddock in North Sea 127 



34. Catch of herring compared with Cahvius 132 



35. Chart of North Sea showing monthly hmits of indicator species 150 



36. Chart of routes and times of approach of indicator species to the British Isles 151 



37. Diagram of diurnal vertical migration 156 



38. Warm- water and normal copepods 1 61 



