154 CEYLON PEARL OYSTER REPORT. 



the ovipositor retracted beneath them. Buchanan White remarks that " the 

 ovipositor appears to consist of four valves," and Nasonov in his figures* shows only 

 two pairs of processes (gonapophyses). Several of the females in the present collection 

 have, fortunately, the ovipositor well extended, and it is not difficult to see that the 

 three pairs of processes usual in the insectan ovipositor are present. 



In a specimen with the ovipositor thus extended the two lateral sclerites of the 

 8th segment (figs. 16, 17, 18, a) are widely separated, and a transversely striated, 

 flexible cuticle (figs. 17, 18, b) is seen to occupy the ventral region of the abdomen 

 behind the 7th sternite. As this cuticle must be folded between the sclerites of the 

 7th and 8th segments when the ovipositor is retracted, and as it lies in front of 

 the genital opening (figs. 17, 18, c), it is to be regarded as an intersegmental 

 membrane, while the small sclerites that are visible behind it a triangular pair 

 (fig. 19, d) supporting the bases of the anterior processes of the ovipositor, and 

 a very slender pair (figs. 17, 18, <P) continuous with the chitinous rim that lies 

 posterior to the genital aperture, must represent the 8th sternite. In front of the 

 genital aperture the intersegmental membrane projects in the form of a hood 

 (figs. 17, 18, c 1 ) with a pointed and forwardly-directed process. 



The anterior pair of gonapophyses (figs. 17, 18, 19, e) are attached to the reduced 

 8th abdominal sternite, as previously mentioned. Each of these processes is broad 

 at the base, which is pale and feebly chitinized except at the outer margin, where 

 a firm dark ridge is developed. Distally the process becomes tapering in form, brown 

 in colour, firm and well chitinized in texture, and beset with rows of prominent bristles. 

 In addition to this main axis of the process there is a small delicate internal limb 

 (figs. 17, 18, e 1 ) which lies close to the genital opening. 



Beneath the lateral sclerites of the 8th segment there lies on each side an elongate 

 sclerite (figs. 17, 19, /), whose shape and relations become evident only when the 

 overlying 8th segment has been removed. Then it is clear that these sclerites (f) 

 belong to the 9 th segment. At its dorsal extremity each is produced into a dark, 

 prominent knob, which lies just anterior to the small " tail-segment " (figs. 16, 17, 19, ;), 

 while at its ventral end each supports the two posterior gonapophyses. The outer 

 pair of these processes (figs. 16, 17, 18, 19, gr) are strong and flexible at the base, 

 while distally each is produced into a straight, firm "guide" on which the inner 

 process slides to and fro. When the ovipositor is extended, the tips of these hinder 

 outer processes do not reach quite as far as the tips of the anterior processes. The 

 inner posterior processes (figs. 16, 17, 18, 19, h) are very long, slender, and flexible 

 at the base, but distally they become somewhat broad and flat, and terminate in 

 a hook-like tip beset with fine hairs. The gonapophyses of the 9th segment remain 

 free from one another, except for an extensive pale membrane (figs. 16, 17, 18, i) 

 which is stretched between them when the ovipositor is extended. This membrane 

 terminates in a pair of short pointed prominences. 



* Loc. cit., figs. 11, 12. 



