282 ELEMENTARY ENTOMOLOGY 



SECTION V. THE ABDOMEN 



Material. Each student should be provided with one alcoholic specimen 

 each of the male and the female locust. The remains of the specimens used in 

 previous sections will be sufficient. 



1. Abdomen of the male. The abdomen of the male locust con- 

 sists of eleven segments ; only seven of these, however, are complete. 



a. The first abdominal segment. This is made up of a curved, 

 dorsal shield, the tergum, which terminates just above the attach- 

 ment of the third pair of legs. This piece partially surrounds the 

 tympanic membrane, or ear, which is a large, crescent-shaped area 

 covered with a semitransparent membrane. Between the ear and 

 the attachment of the legs are the spiracles, which have already 

 been noted. The ventral part of the first segment, the sternum, 

 is not attached to the tergum, owing to the large size of the attach- 

 ment of the legs. The pleura are entirely absent. 



b. The second to eighth abdominal segments. These are all quite 

 similar, consisting of a dorsal tergum, which extends laterally to 

 near the ventral part of the body, where it joins the sternum. 

 The pleura, or side pieces, noted in connection with the thorax, 

 have been inseparably fused to the tergum. One pair of spiracles 

 is located at the anterior margin of each segment near the union 

 of the sternum and tergum. 



c. Segments nine and ten. The terga of these two segments 

 are partially fused together, the union of the two being indicated 

 by the presence of a transverse suture. The sterna of these two 

 segments are entirely fused and much modified, forming a broad, 

 platelike piece. 



d. Segment eleven. This is represented only by the tergum, 

 which forms the terminal, dorsal, shield-shaped piece. 



e. The cerci. These are a pair of plates attached to the lateral, 

 posterior border of the tenth segment, and extend back past the 

 end of the eleventh tergum. 



f. The subgenital plate . This is attached to the ninth sternum 

 and forms the most posterior ventral plate of the body. 



g. The podical plates. These lie directly beneath the cerci and 

 ventral to the eleventh tergum. The anus opens between these 

 plates, and the genital chamber lies directly below them. 



