499 



— by a large triangular plate on each side of the abdomen, remnants 



of the sternites of the eighth segment — to the small plates (pleu- 



ristes) bearing the abdominal spiracle of the eighth segment; the 



upper part {(f-) attaches to the anterior edge of the ninth segment. 



The points ofattachment are indicated in Fig. 11 by black dots. 

 The tip only of the upper part ( g'^ ) 



of the ovipositor is split or divided; the 



basai portion of the lower part (g^) is 



also connected by membrane, so that 



in al! probability the génital pouches 



of the female arise from two médian 

 fevaginations on the 

 eighth andninth seg- 

 ments respectively (or 

 themembranebetween 

 thèse two segments), 

 and those of the maie 

 from one médian eva- 



gination on the ninth segment. [It whould be 

 observed, however, that it would be diffîcult to say 

 Fig. 12. precisely whether the whole génital armature is 



formed partly from the intersegmental membrane and partly by the 



sternal plates, since it is practically impossible to exactly define 



where the intersegmental membrane begins 



and the plates end. Since the primitive nym- 



phal génital area is ail membraneous com- 



pared with the adjacent integument, and 



since some of the invaginations (pouches) 



certainly arise from the intersegmental mem- 

 brane, it is very probable that as a matter of 



fact they ail arise therefrom, and that the 



membrane bas become more extensive to 



provide for this.] The Membracidae are in 



many ways, including the genitalia, highly 



specialized insects, and one would scarcely 



expect any trace of the primitive paired 



génital orifices to api»ear, even in the earliest 



nymphal instar. 



During the earlier nymphal instars the 



testes and ovaries are are practically indistin- 



guishable. Both organs are surrounded by a mass of nutrient 



cells, and appear as whitish, globular masses; thèse nutrient cells 



later on form a plate Connecting the génital organs, and are 



gradually absorbed by the génital cells forming the growing 



ANNALES DE LA SOC. ENTOM. DE BELQIQUB, T. LVII, 4-VII 1913. 14 



Fie. 1:1 



