154 INTRODUCTION TO ZOOLOGY. 



8. What are the siphons? 



9. What are the adductor muscles? 



10. What closes the shell? 



11. What opens the shell? 



12. How does the clam get food? 



13. Where is the heart? 



14. What and where is the cloacal chamber? 



15. What causes tlie current to go over the gills? 



16. How does a clam move? 



The Snail. 



17. Define these parts of a snail : spire, whorl, apex, 



aperture. 



18. Distinguish between right- and left-handed shells. 



19. What is the odontophore? 



20. How does a snail crawl? 



21. How distinguish a lung-breathing snail from a 



gill-breathing one? 



22. How distinguish a flesh-eating snail from a vege- 



table-eating one? 



The Earthworm. 



23. How does an earthworm breathe? 



24. How does an earthworm crawl? What muscles 



does it use? 



25. What are the setae? What is their use? 



26. What are the reproductive organs? 



27. Why does the earthworm come out of the ground 



during a rain? 



28. What is the cingulum? 



The Starfish. 



29. How many arms has a starfish? 



30. What is the madreporic body? The stone canal? 



What are the tube feet? 



31. Describe the water vascular system in full. 



