56 



EXTERNAL ANATOMY. 



FIG. 29.— Ventral view of the 

 prothoracic sternum of Melan- 

 oplus bivittatus. Original. 



' the limbs. The mesothorax and 



metathorax are much more com- 

 plicated, and together with the first 

 abdominal segment, are soldered 

 into a firm-walled box. The flat- 

 tened ventral surface of this box is 

 made up of three pieces ; the meso- 

 sternutn {meso. st), which consists 

 of an anterior median portion and 

 two nearly rectangular posterior prolongations ; the 

 metasternum {meta. si) is a somewhat larger plate, which 

 consists of an anterior square tongue filling the space be- 

 tween the posterior horns of the mesosternum, and a large 

 pentagonal portion. The first abdominal sternum {1st ahd. 

 st) is morticed into theposterior margin of the metasternum 

 in nearly the same way that the latter is joined to the pre- 

 ceding sternum. 



In this ventral view of 

 the thorax, (Fig. 30), the 

 lower ends of the epis- 

 terna and the fossae (/b) 

 for the articulation of the 

 legs, are visible at the 

 sides of the sterna. Par- 

 allel with the anterior 

 half of the mesosternum 

 are the lower ends of the 

 mesothoracic episterna 

 [meso. epis). Parallel 

 with the posterior half of 

 the mesosternum are the 



FIG. 30.— Ventral view of the thorax, of foSS£e of the SCCOud pair 

 Melaaoplas bivittatus. Original. „ - ,— , . , 



oi legs, ihe inner bor- 

 ders of these fossae are not formed by the mesosternum it- 

 self, but by slender horn-like backwards prolongations of 

 the low^er end of the episternum. Parallel with the anterior 



--m&vo.tfiii. 



