HARD PARTS OF THE GRASSHOPPER. 251 



united to that of the metathorax, and has been already 

 described. 



(i.) The tergum is soft, membraneous, and dark-colored 

 like those of the thorax, and is strongly crested in the 

 median line. Near its lower edges are a pair of large 

 apertures closed by membrane, the auditory organs. On 

 the anterior margin of this orifice is a much smaller open- 

 ing, the first abdominal spiracle. 



b. The remaining abdominal segments are composed of 

 a narrow sternal portion and a much larger tergal portion. 

 The two sides of the tergum meet along the back to form 

 a ridge. Near the lower margin of each half of the ter- 

 gum are a couple of longitudinal furrows, the traces of the 

 sutures between the epimera and episterna. Near the 

 anterior angles of the episternal regions of the second, 

 third, fourth, fifth, sixth, seventh and eighth segments are 

 the openings of the spiracles. 



As the structure of the terminal segments of the abdo- 

 men differs considerably, according to the sex of the 

 individual, both males and females should be studied and 

 compared with each other. The females are more abun- 

 dant than the males, and may be recognized by the presence 

 of the strong, blunt forceps-like ovipositor which forms 

 the posterior extremity of the body. As the male abdo- 

 men is the simplest it should be examined first. 



9. The abdomen of the rnn1i\ 



a. In a ventral or a side view (Fig. 135) nine distinct 

 movable sterna ( 6* to 9* ) are visible ; they are nearly 

 equal in length and similar in shape. 



(i.) Posterior to the ninth sternum (*) the ventral 

 surface of the body is occupied by a large spoon-shaped 

 sub-genital plate (a), convex below and concave above. 

 The posterior margin of this plate (Fig. 134, a) is deeply 

 notched upon the median line. 



