22 



Prosternum. — On the ventral surface of this segment 

 between the legs there is a sclerite which bears a large 

 tubercle ; this is the sternum of the prothorax or prosternum, 



Prosternellum. — The sternellum of the prothorax, or the 

 prosternellwn^ is a narrow, transverse sclerite, which is close- 

 ly united to the following segment. 



Lateral parts. — Owing to the great development of the 

 pronotum, which covers the larger portion of the sides as 

 well as the dorsal surface of the prothorax, the lateral parts 

 of this segment are rudimentary. The following named 

 sclerite, however, may be distinguished. 



Epister7iuin. — Between the pronotum and the end of the 

 lateral prolongation of the prosternum, which extends on 

 each side of the segment cephalad of the leg, is a conspicu- 

 ous triangular sclerite ; this is the episternum. 



Add the episternum to the drawing of the lateral aspect of 

 the pronotum. 



MESOTHORAX AND METATHORAX. 



Union of these segments. — The second and third 

 thoracic segments are firmly joined together, forming a box 

 to which the two pair of wings and the second and third 

 pairs of legs are joined. Owing to the intimate union of 

 these two segments it will be easier to describe them together 

 than separately. 



With fine pointed scissors cut away the caudal border o-f 

 the pronotum, that part which overlaps the mesonotum ; be 

 careful not to break the membrane connecting the protho- 

 rax and mesothorax. 



Dorsal part (mesonotum and metanotum). — The 

 dorsal part of the mesothorax is termed the mesonotum^ that of 

 the metathorax, the metanotum. Unlike the pronotum these 

 parts are confined to the dorsal aspect of the body. By cut- 



