76 INTRODUCTION TO ZOOLOGY. 



16. Describe the two pairs of antennse. 



17. Where are the ears? 



18. How distinguish the male from the female? 



19. How many body segments ? What indicates the 



number ? 



20. Which body segment bears no appendage? 



21. What pairs of legs are furnished with pincers? 



22. Where is the stomach? 



23. Describe the nerve cord. How many ganglia? 



24. Where is the heart ? How does the blood get into 



the heart? 



25. What kind of blood has the crawfish? 



26. What muscles enable the crawfish to swim? 



27. Why does the crawfish swim backwards? 



28. How is a crawfish enabled to stay so long out of 



water ? 



29. Where are the eggs carried? 



30. Of what is the shell composed? 



31. What is meant by the molting of a crawfish? 



The Spidee. 



32. How many body divisions has the spider? 



33. How is the web produced? 



34. What is silk? Where are the spinnerets? 



35. How many legs has the spider? 



36. What are the breathing organs? 



37. How many eyes has the spider? Are they simple 



or compound ? 



The Centipede. 



88. How many body segments has the centipede? 



39. Where are the maxillipeds borne? 



40. Where does the centipede live? What is its food? 



41. Is there any difference between the thorax and 



the abdomen? 



42. How does a centipede differ from a caterpillar? 



