23 



ting away the caudal part of the pronotum as indicated above 

 and spreading the wings laterad, these parts are exposed. 

 Each consists of a nearly square area. To the lateral mar- 

 gins of the mesonotum is articulated the first pair of wings ; 

 and to the lateral margins of the metanotum, the second pair 

 of wings. 



The sutures indicating the outlines of the sclerites of 

 which the mesonotum and metanotum are composed, are not 

 well defined ; there is consequently some difficulty in deter- 

 mining the limits of the sclerites ; and a drawing of this part 

 will not be required. 



In each of these segments only two of the four dorsal 

 sclerites are well developed ; these are the scutum and the 

 scutellum. The scutum occupies the cephalic half of the seg- 

 ment, the scutellum the caudal half. The scutellum consists 

 of three parts : a central, shield-shaped part, which in this 

 species is closely united to the scutum ; and on each side a 

 part extending to the base of the wing. The caudal border 

 of the scutellum is thickened and is connected on each side 

 with the caudal border of the base of the wing by a cord-like 

 structure. 



Note. — In those insects where the praescutum and postscutellum are well 

 developed, they usually extend entad and are often concealed within the 

 thorax. The connection of the scutellum on each side with the caudal bor- 

 der of the base of the wing, is an excellent guide in tracing the homology of 

 the parts of the mesonotum and the metanotum. 



Ventral part. — On the ventral surface of the body be- 

 tween the legs of the second thoracic segment is a large 

 sclerite ; this is the sternum and the sternellum of the meso- 

 thorax combined. The cephalic margin of this sclerite is 

 nearly straight ; the caudal margin, deeply notched by a 

 large, nearly square incision. The part in front of this 

 notch is the sternum of the mesothorax or mesosternufu, the 

 two parts, one on each side of this notch, are the widely sep- 



