198 



In the female nymph the rudiments of the genitalia first arise as 

 four small evaginations of the génital area, visible in the second 

 instar {g^ and g^ -^ g^ , a, Fig. 10). The two anterior or ventral 

 pouches (g^) arise from the intersegmental membrane between the 



eighth and ninth 

 segments; the two 

 posterior or dorsal 

 pouches (g^ -\- g"^ ) 

 belong to the ante- 

 rior end of the 

 ninth segment, and 

 at an early date 

 (third instar) the 

 distal end of each 

 grows out into two 

 pouches, thus for- 

 ming four dorsal 

 pouches. Altoge- 

 her theret are now 

 six pouches, their 

 distal ends pointing posteriorly. The basai portion of the pouches 

 g^ and g"- extends inwards and anteriorly to form the ectodermic 

 portion of the vagina or utérus {v, b, Fig. 10). The mesodermic 

 portion of the oviduct is at an early instar a thick mass of cells 



with a small lumen. 

 The two parts, ec- 

 todermic and meso- 

 dermic, afterwards 

 meet and fuse. Ex- 

 cept for enlarging 

 and lengthening, 

 the pouches remain 



much the 

 same till the 



last moult to ^-^ y / 

 adult at ihe (^TT^^^^^^'Z^^ 



.-/ 



ova 



Fig. 9. 



end of the 

 fifth instar, 



f 



Fig. lOb. 



when g'- (Fig. 11) form the upper part of the ovipositor (Fig. 12), 

 and g^ the lower part or so called sheath ; g^ forming the third gona- 

 pophyses. A séries of transverse vertical sections through the génital 

 area of the eighth and ninth segments is shown in Fig. 13, a 

 being the most posterior and cl the most anterior section. In the 

 adult female the lower part of the ovipositor {g\ Fig. 12) attaches 



