PROBLEM I . The Kinds of Avimals of the Earth 60 



eardrum, on each side under the wings on the first segment of the abdo- 

 men. Describe the two pairs of wings and discuss their use. Does your 

 specimen differ from the picture in the text? How? How many joints 

 are there in each of the three legs? What is each pair fitted for? Describe 

 the foot closely. Study the mouth parts and compare with Fig. 94. How 

 is each part used? 



2. How does a butterfly resemble and differ from a grasshopper? 

 Study a specimen. Follow the directions for study of the grasshopper, 

 and describe each part of the butterfly. Feel the wing. If you have a 

 microscope examine some of the powder which comes off on your finger. 



3. Since there are half a million species of insects, it would be difficult 

 to learn much about this large group in a short time. But you will have 

 made a good beginning if you know exactly how you can recognize an 

 insect, that is, if you have become acquainted with grasshoppers and 

 their relatives, moths and butterflies, flies, bugs, beetles, and the social 

 insects and can distinguish one order from another. Remember that be- 

 coming acquainted includes recognizing them in all stages of their life 

 histories. Write up all this in your notebook. 



4. Draw a diagram of the top view of an insect and another of a spider 

 to show the important differences between the two groups of animals. 



5. Shrimp and lobsters are easy to obtain in the market; crayfish are 

 common in fresh water streams. Study and describe the body regions 

 and the appendages of one of these crustaceans. Study the antennae and 

 the eyes and compare them with the antennae and eyes of the grasshopper. 

 What differences can you find among the many pairs of legs of the 

 crustacean? How might it use these various kinds of legs? What is the 

 advantage of jointed legs? Of segmentation in the antennae? 



If you have live animals, place them in deep water in a large tank and 

 then in a shallow tray to watch the methods of locomotion. Hold the 

 crayfish in your hand; does it exert much strength in trying to escape? 

 Do you think the animal is well protected by its color? Gently touch the 

 eyes with a pencil. What happens? Have you made any other observa- 

 tions of your own? If so, discuss them with the class. 



6. Arthropods affect man in many ways. Prepare lists of those that 

 are useful and those that are harmful, telling how in each case. 



7. You have become acquainted with four groups of arthropods be- 

 sides the insects. Name a few forms in each of the five groups. Tell how 

 they live. 



8. Dissection of a clam. If you crack one valve of the shell and remove 

 the pieces gently you will see the mantle, a thin skin next to the shell, 

 and the gills. Can you find the muscles that hold the shells together? 

 Open an oyster and compare its structure with that of the clam. 



9. Collect some earthworms and keep them in a box of earth with glass 

 sides. Watch them. Write up your observations briefly but accurately. 



10. To study the organisms in a hay infusion. Boil a small handful of 

 hay and two or three wheat seeds in half a quart of water. Allow it to 



