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 largest joint of the hind leg for a row of small spines visible with the aid of a hand lens (Fig. 111). The sound is produced by the outer wings rubbing against the spines. Have you noticed whether the sound is produced while the insect is still or in motion? Why? The male grasshoppers of some species, instead of having spines, rub the under side of the front wing on the upper side of the hind wing.

—A,, z, used in chirping.

B, the same more enlarged.

Wings.—To what is the first pair of wings attached? The second pair? Why are the wings not attached to the prothorax? Why are the wings attached so near the dorsal line of the body? Why are the second and third rings of the thorax more solidly joined than the first and second rings?

Compare the first and second pairs of wings in shape, size, color, thickness, and use (Fig. 112). How are the second wings folded so as to go under the first wings? About how many folds in each?

Draw a hind wing opened out.

Head.—What is the shape of the head viewed from the front, the side, and above? Make sketches. What can you say of a neck? Is the head movable in all directions?

What is the position of the large eyes? Like the eyes of the crawfish, they are compound, with many facets. But the grasshopper has also three simple eyes, situated one in the middle of the forehead and one just above each antenna. They are too small to be seen without a hand lens. How does