4 GENERAL ZOOLOGY 



and the spiny tibia (Fig. 3, o). Each leg ends in a series of 

 three segments, forming the tarsus (Fig. 3, 7), the last segment 

 of which bears two claws (Fig. 3, 8), with a pad, the pulvillus 

 (Fig. 3, 9), between them. 



Of the two pairs of wings (Fig. 2, 17, 18), the first is attached 

 to the surface of the mesothorax, the second to the m eta- 

 thorax. The anterior pair is somewhat hardened, forming 

 protective covers for the more delicate posterior wings, which 

 are folded like a fan beneath them. The latter only are used 

 in flight. The wings are simple extensions of the body-wall, 

 and not jointed appendages like the legs. On the sides, just 

 beneath the posterior edge of the collar on the prothorax, is 

 a pair of breathing openings, or spiracles (not shown in the 

 figure). Two spiracles are placed just above the junction of 

 the second pair of legs (Fig. 2, 20), and the abdomen bears 

 eight pairs along the sides (Fig. 2, 21, 22). 



The Abdomen. The first abdominal somite is much larger 



o 



than the others, though it does not form a complete ring, 

 owing to the space occupied by the cavities for the insertion 

 of the hind legs. Each side of this somite bears an oval spot 

 consisting of a thin skin stretched across a small cavity and 

 connected with a nerve, the whole forming an ear, or auditory 

 apparatus (Fig. 2, 19). The end of the abdomen in the female 

 is more tapering than in the male, and is furnished with two 

 pairs of blunt spines, which form an egg-laying instrument, or 

 ovipositor (Fig. 3, 36, 37). 



The Digestive System. After this brief review of the main 

 features of the external anatomy of the locust, we turn our 

 attention to the organs of the interior. And first, owing to 

 its size and the ease with which its parts may be examined, 

 we may consider the digestive system. The function of the 

 digestive system of an animal is to prepare the food for use 

 by the different organs of the body. In the locust the organs 

 of digestion are the food-tube, or alimentary canal, and its 



