252 



JIANDBOOK OF INVERTEBRATE ZOOLOGY. 



(ii.) Above this plate is a large chamber open behind 

 and at the sides, the genital chamber (Fig. 135, y). 



(iii.) On the lower floor of this chamber, and therefore 

 on the upper surface of the sub-genital plate, is the male 

 reproductive orifice. 



b. In a dorsal view (Fig. 134) the terga are substan- 

 tially alike as far as the eighth. 



(i.) The eighth (8) is a little shorter 

 than the seventh. 



(ii.) The ninth (Fig. 134, 9} is only 

 about one-fifth as long as the eighth, and 

 is immovably united to the tenth, a faintly 

 marked suture separating the two. 



(iii.) On the median line the tenth 

 tergum (Fig. 134, 10) is very narrow, 

 but at the sides it is about as long as the 

 ninth. The posterior margin of the tenth 

 tergum is sharply defined. 



FIG. 134. Dorsal view of end of abdomen of 

 male Acridium Americanum. (Drawn from nature 

 by W. K. Brooks.) 

 FlG 134 For explanation of letters and figures see Fig. 136. 



(iv.) The eleventh tergum (Fig. 134, 11) is a movable 

 shield-shaped plate upon the median dorsal surface. It is 

 about as long as the eighth, and it is divided into two 

 nearly equal portions by a faint tranverse suture. In 

 shape it is quite different from the other terga, and its 

 sides and posterior margin are free. 



(v.) On each side of this plate the outline of the dorsal 

 surface of the body is completed by a setose movable plate 

 (Fig. 134, d), about as large as the eleventh tergum, the 

 cercus. This plate projects back from the lateral margin 

 of the tenth tergum, to which it is movably articulated. 



