An OrtJiopterons Insect. 131 



represent the tergum of an eleventh segment. This dorsal 

 piece rests laterally upon a pair of triangular plates, the 

 podical plates, the lower edges of which follow the course 

 taken by the lower edges of the ninth and tenth segments. 

 Resting laterally upon the podical plates are short pointed 

 processes, the cerci. The ovipositor fills up that opening at 

 the posterior end of the body, which is bounded by the free 

 edges of the podical plates and the eighth sternal piece. 

 The ovipositor is made up of two dorsal and two ventral 

 pieces, all of which have sharp chitinous points. The anus 

 opens between the dorsal pieces, and the oviduct between the 

 ventral. 



The abdomen of the male is relatively smaller than that of 

 the female. The ninth and tenth segments are provided with 

 a common sternal plate. The podical plates are reduced, 

 while the cerci are relatively larger. A subgenital plate lies 

 below the podical plates and continues posteriorly the ven- 

 tral series of sterna. 



Spiracles will be observed as follows : The most anterior 

 is on the posterior edge of the prothorax, under the lateral 

 fold of the shield-like piece. The second is at about the 

 same level, behind the edge of the mesothorax. The third 

 pierces the first abdominal ring just within the anterior mar- 

 gin of the auditory organ. The seven succeeding abdominal 

 rings are each provided with spiracular openings. Spiracles 

 do not occur on the ninth and tenth segments. 



Internal Anatomy. Carefully open the animal along 

 the mid-dorsal line. 



The Circulatory System. The heart will be found 

 occupying the same place that it has occupied in many 

 other Arthropods, and presents no remarkable features. 



