THE GRASSHOPPER. 51 



IV. Legs. Compare the first and second pairs of legs 

 with the third pair, in color and surface markings, posi- 

 tion, size, and use. 



Find in one of the hind legs the usual segments, 

 coxa, trochanter, femur, tibia, and tarsus. Note : 



1. The large club-shaped femur. Within it are the 

 powerful muscles used in leaping. 



2. The double row of spines on the sides of the 

 tibia. 



3. The two pairs of spurs at its lower end. 



4. The tarsus. Examine its lower surface and the 

 hooks at its tip. 



What is the advantage of all these spines and hooks 

 and pads ? 



Make an enlarged drawing (lateral view) of one of the 

 hind legs in its natural resting position, naming all the 

 parts in the drawing. 



V. The Abdomen. Count the segments of the abdo- 

 men as seen on the ventral surface. In the female there 

 are eight, and in the male nine. The abdomen of the 

 female terminates in an ovipositor, having four subequal 

 points, which are used for making holes in the ground 

 for the reception of eggs. The four points are repeat- 

 edly pressed together, pushed into the ground, and there 

 separated, thus pressing the earth aside, until a hole is 

 made of sufficient depth, when the eggs are deposited 

 in the bottom. An elongated, bilobed, subgenital plate 

 at the ventral surface terminates the abdomen of the 

 male. 



Observe on either side of the abdomen a longitudinal 

 groove, and just above it a row of evident spiracles. 



Observe on either side of the first abdominal segment a 

 semicircular depression, across which is stretched a thin 

 membrane. This is called the tympanum, and is supposed 

 to be an organ of hearing. 



