1918] Thoracic Sclerites of Hemiptera 235 



Pleuron. The metathoracic pleuron exhibits several points 

 of difference from the primitive type. In the lower part of the 

 episternum of the Cercopidas (Figure 6) will be noticed a short 

 suture running parallel to the pleural suture. In the Ful- 

 goridas (Figures 8 and 9) this suture is possibly represented by a 

 membranous cleft, to be described later. The metapleuron, • 

 metasternum and metacoxa of the Fulgoridas (Figures S and 9) 

 present a very remarkable and puzzling condition. Hansen, 

 1890, figured and described the coxa and its surrounding parts, 

 but was mistaken in his interpretation of the boundary of the 

 coxa. He did not consider the upper portion of the part labelled 

 meron (me) in Figures 8 and 9 as a part of the coxa. Since 

 this plate bears muscles extending to the subalar region and such 

 muscles characteristically connect the meron with that region 

 in other insects, it is unquestionably a part of the coxa. The 

 coxa is, indeed, so fused with the pleuron and sternum as to 

 make these parts extremely difficult of interpretation. Added 

 to this confusing state is the substitution of a considerable 

 amount of membrane for chitin in these parts. On comparing 

 Figures 8 and 9 it will be seen that there is a marked variation 

 in the two forms. Essentially, however, they are very similar. 

 In Ormenis sp. (Figure 8) the parts can be more easily identi- 

 fied. It will be noticed that in this form the coxa (ex) extends 

 dorsally to a point not far from the wing base and that a lobe 

 of the episternum covers the anterior part of the coxa to some 

 extent. This lobe being transparent, the true limits of the 

 coxa can be distinguished through it. That the coxa extends 

 posteriorly to the point indicated in the figures is shown — as 

 mentioned above — by the presence of characteristic muscles 

 running from the subalar region to the meral region (me) of 

 the coxa. 



The coxa, then, in Fulgoridee is rather extensive; it is 

 divided into a true coxa, or veracoxa (vex), and a large meron 

 (me), which in turn is divided into two parts. The coxa is. 

 moreover, immovable as a result of its close fusion with the 

 other parts. The large non-chitinous areas in the pleural and 

 sternal regions, however, probably impart a certain elasticity 

 to the coxa, which doubtless compensates for its immobility to 

 some extent. These membranous areas are to be found in the 

 episternum, the epimeron and the sternum. In the episternum 

 the membranous portion forms a cleft, nearly bisecting the 



