197 



indistinctly ti'ilobed (g^ , h, Fig. 7), the two latéral lobes being very 

 small ; ail thèse evaginations or pouches are directed posteriorly. 

 The lip of the médian lobe is invaginated (y, c, Fig. 7) ou ils 

 ventral face, forming a laterally-compressed tube extending ante- 

 riorly wilhiti the lobe; this tube subsequeutly becomes the 

 ectodermal porliou of the ejaculatory duct (ejd, d, Fig. 7). AU 

 thèse pouches, after the third moult (fourth instar) are much 

 lengthened, and the two latéral lobes of the dorsal evagination 

 become constricted off from the mé- 

 dian lobe, so that altogether five 

 pouches are now easily discerned. 

 The inlegument around the genilal 

 area is also puckered into a ridge 

 (z, Fig. 7). After the fourth moult 

 (fiflb inslar) ail thèse pouches are 

 furlher enlarged and lengthened ; the 

 invagination of the distal part of the 

 médian lobe on its ventral face to •' X 

 form the ejaculatory duct is distinctly visible, 

 and extends inwards and anteriorly as a large 

 diameter tube till it meets and fuses with the 

 mesodermic portion of the duct, which at an 

 earlier stage is a tliick mass of cells with a 

 very small lumen. Transverse vertical sections 

 through the anterior part of,' the ninth segment 

 of a nymph of the fifth instar, just before moul- 

 ting, are shown in Fig. 8 a being the most 

 posterior and d the most anlerior section. Thèse 

 sections pass through the génital area and 

 pouches. After the fifth and last moult (to adult) 

 the dorsal médian lobe appears as the adult pénis 

 {g''- , Fig. 9) the two latéral dorsal lobes as the 

 third gonapophyses ( g'^ ), and the two ventral 

 pouches as the first gonapophyses ( g(* ). The raised 

 integuraent (r, Fig. 7) around the génital area 

 forme in the adult the narrow, latéral, terminal plates (IX, tp) 

 belonging to, butseparated by a membraneous area from the ninth 

 segment. 



If the abdomen of â nymph just ready to moult is boiled in 

 potash and the adult integument withdrawn from the nymphal 

 skin, the genitalia are seen to be Ihickly clothed with long hairs, 

 few of which are présent in the adult when it moulls naturally. 

 They are evidently the so-called moulting or casting hairs which 

 assist in loosening and thrusting otï tlie old integument. 



