Dr. Cockayne on Gynandromorphous Lepidoptera. 323 



wall (13) allowing the passage of a penis (7) narrower than 

 usual but with well-formed oedaeagus, vesica and cornuti, 

 the latter in two groups, a large group of large spines and a 

 small group of small ones. 



The tegumen and cingula (16), which in the normal male 

 form a complete ring or girdle of stout chitin with a lateral 

 hinge on each side, ended in the gynandromorph slightly to 

 the left of the middle line. Thus on the male side all the 

 parts were present, but the uncus and penis were small. 

 The uncus is in reality a double organ, and in many groups 

 is bifid. It is homologous with the two halves of the 

 ovipositor. 



The uncus was small because it was only half the ordinary 

 double uncus, and I regard the narrowness of the penis as 

 being due to the same cause. It was small because it was 

 formed from only half the normal primitive epithelial mass 

 of cells. There was reduplication of the clasping apparatus, 

 valve and harpe, and partial reduplication of the cingula. 

 On the left side was a small malformed bursa copulatrix 

 and caput bursae, an abnormally small ostium bursae or 

 genital opening and a normal rod of the ninth segment. 



Thus the female parts were all present, but with the 

 exception of the rod, a paired organ, all were small in size 

 owing to their origin from half the usual number of 

 epithelial cells. 



The second gynandromorphous A. populi was not per- 

 fectly halved, the right side was predominantly female, 

 and the left predominantly male. The wings on the left 

 approached the female in shape, and the antenna on the 

 left showed the coarse hairs peculiar to the male, though 

 much less well-developed than those on the right. The 

 colour, red brown, was the same on both sides. 



Internally there was only one gonad, an ovary with four 

 follicles, which lay on the right side of the body. There 

 was also an oviduct, cement gland, spermatheca and very 

 small bursa copulatrix and caput bursae, but no ductus 

 seminis. On the male side there was only a penis with a 

 soft saccular mass of chitin representing the blindly ending 

 ductus ejaculatorius. 



The external genitalia showed a completely halved 

 arrangement. On the left side of the tenth segment was 

 a small uncus and on the right a normal half ovipositor, 

 with its directing-rod. Opposed to the uncus was a gnathus 

 of small size, and between them lay the anal opening. On 



