ORTHOPTERA 45 



3. In the male grasshopper there are nine segments visible 

 on the ventral side, and an elongated, bilobed subgenital 

 plate terminates the abdomen beneath. 



4. The hearing organs. If the wings be raised, so as to 

 uncover the side of the abdomen, on the middle of 

 each side of the basal segment will be seen a small oval 

 depression, across the bottom of which is stretched a 

 thin vibrating membrane; this being remotely com- 

 parable to the drum of the ear is called a tympanum. 

 A nerve connects the inner side of it with the central 

 nervous system. 



5. The sound-producing organs. These belong to the males 

 only, and consist of a file and a scraper. The micro- 

 scopic file is on the inner side of the hind femur, and it 

 rasps across the edge of the partly extended wing, 

 throwing that into vibration, and thus producing the 

 "music." By searching the inner surface of the femur 

 with a lens the minute pegs may be found in a row at 

 the lower margin of the braided central area. This 

 scraper is best developed in some of the band-wing 

 grasshoppers. These sing only in flight. 



Developmental stages. If grasshopper nymphs of all sizes 

 have been collected, compare those of one species together, 

 and see if they cannot be arranged in a series to show five 

 nymphal instars. The size of the horny head capsule will 

 remain rather constant between molts. Study also some 

 preserved specimens that have been fixed in the act of 



