24 Studies in the Hybrid Bistoninae. IV 



Terminally appear the two ovipositor lobes bearing, as is invariably the 

 case in all of the intersexes I have examined, a small detached portion 

 of the uncus ( U\ a further fraction of which occurs at U'. Immediately 

 to the left of this is an attempted duplication of the ovipositor. Fused 

 with the latter organ at G is the squamous gnathos tip. Curiously 

 enough, this curious stranding of the tip of the gnathos is the normal 

 state of affairs in certain Bistoninae, e.g. Haggardia subalbata (Warren). 

 Close to the gnathos are two minute chitinous rods or bars ; these are 

 the rudiments of the tergite of the 9th abdominal segment of the male 

 or, otherwise, they represent the " roof " of the tegumen. 



Connected with the base of the ovipositor posteriorly are visible the 

 inner pair of directing rods almost normally placed. However, they are 

 so situated as to suggest their homology with the ventral section of the 

 male tegumen ring. Similarly, the uniform occurrence of the uncus at 

 the ovipositor tip indicates that these structures are homologous, and 

 that both are developments of the 10th abdominal segment. 



Half-way down the ovipositor are to be found the two male valves, 

 fully developed, if abnormal in shape. These possess the ordinary 

 thickened and raised costa and likewise the inturned patch of stiff 

 bristles on their outer extremity. Thrown to the left between them 

 appears the aedoeagus, on the vesica of which are the cornuti of a fully 

 sexed male. 



To the left of the first pair of rods are the degenerate remains of 

 the second pair, the left member of which is divided into two parts, 

 one small lying at the base of the 7th segment and a further more 

 important portion traversing the left upper rod above. Of the right 

 lower rod a mere fragment crosses the same rod at its base. 



Just to the left of the larger detached portion of the second pair is 

 the ostium with its guard-flap well displayed ; there, too, may be seen 

 a part of the female 8th abdominal segment. Passing from it is the 

 ductus bursae in a very elongated form, ending in a bursa copulatrix 

 much less globular than usual but, nevertheless, exhibiting a well- 

 developed, somewhat circular, granulated signum, armed at the edges 

 with a series of small spines or spiculations. 



Precisely in front of the spiracles of the 6th segment, and resting on 

 the ductus bursae, is a strong free chitinous ring ; this is a duplicated 

 8th abdominal segment. That occurring at the correct point is the 

 corresponding segment of the female ; the present is that of the male. 

 Though small, it is still perfect in shape. Its internment is necessitated 

 by the essentially external nature of the ostium bursae. 



