THE GRASSHOPPER AND THE SNAIL S 



on the inside from which a nerve leads to one of the internal 

 nerve-centers. This is a much simpler kind of ear than we 

 possess, and the locust probably cannot hear nearly as well 

 as we can. Note on each side of each abdominal body-ring 

 (except the last) a tiny blackish spot. These are breathing 

 pores or spiracles which open into a system of internal tubes 

 that carry the air to all parts of the body. The locust does 

 not take in air through nostrils on the head nor through the 

 mouth, but by means of these many lateral openings in the 

 body-wall. There is a spiracle near each tympanum, and 

 one on each side of the thorax near the insertion of the mid- 

 dle legs. At the very tip of the abdomen are several small 

 projecting parts which differ in the male and female. The 

 female has two pairs of strong, curved, pointed pieces called 

 the ovipositor or egg-laying organ. When the locust is ready 

 to lay its eggs, by means of this strong ovipositor it bores a 

 hole in the ground into which the abdomen is pjished and the 

 eggs laid at the bottom. The male locust has a swollen, 

 rounded, abdominal tip, with a few short inconspicuous 

 pieces on the upper surface. 



Examine now a live locust and see how it uses its legs 

 in walking and hopping; how it moves its jaws sidewise, 

 not up and down as with us; how its antennas keep "feeling" 

 about in front of it when it is walking; how the abdomen 

 keeps up a slight but distinct and regular expanding and 

 contracting. This movement forces air in and out of the 

 body through the spiracles; it is the breathing motion. 



Make a drawing from lateral view of the whole body of 

 the locust, showing and naming all the parts studied. 



(A more detailed study of the external structure of the locust can 

 easily be arranged for by reference to Comstock and Kellogg's "Ele- 

 ments of Insect Anatomy," 5th ed.) 



The pond snail. — Pond snails may be found in almost 

 any pond, and live specimens may be easily kept in the 

 schoolroom aquarium or simply in bowls or glass jars of 



