250 HANDBOOK OF INVERTEBRATE ZOOLOGY. 



thorax is formed by two nearly square areas, which occupy 

 the space between the Agings. They are soft and membra- 

 neous, and the pieces which compose them are not sharply 

 defined. 



1. The anterior border of each is formed by a narrow 

 plate, the prescutum (Fig. 133, a). 



2. Back of this is a large, convex, dark-colored, glisten- 

 ing surface, the scutum (6). 



3. Behind the scutum is a membraneous piece upon the 

 median line, thescutellum (d). 



a 4. The posterior margin is occu- 



pied by a long, narrow, light-colored 

 piece, the post-scutellum (e). 



Fig. 133. — Mesonotum, or dorsal surface of 

 Mesothorax ( Acridium Americanum). (Drawn 

 from nature by W. K. Brooks. ) 



a. Prescutum. b. Scutum, d. Scutellum. 

 Fig. 133. e. Postscutellum. c. Patagium. 



5. Outside the scutellum on each side is an irregular, 

 projecting, movable piece, the patagium (c), to which the 

 wins: is articulated. 



(vii.) Make a sketch of the dorsal surface. 



8. The Abdomen. 



This is made up of a number of segments without 

 appendages, movable upon each other, and presenting 

 only slight differences. The typical number of abdominal 

 segments appears to be eleven, and in both sexes of the 

 gi'asshopper eleven terga are present, although only eight 

 sterna are visible in the female and nine in the male. 



a. The first abdominal segment is somewhat different 

 from the others, and its sternal and tergal portions are 

 widely separated. The sternal portion is immovably 



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