Gynandromorphous Lepidoptera. 325 



gnathus enclosing the anal canal on the right side and a 

 perfect half ovipositor and directing-rod on the left. A 

 valve lay on the right side, distorted and possessing a 

 curious prolongation of very thin chitin, with an up-curved, 

 knob-like extremity. There was also a malformed harpe. 

 A small piece of chitin (13) probably represented the ring- 

 wall or penis sheath, and the penis itself was very short 

 and was tilted so that the vesica pointed ventrally. The 

 very small cornuti on the vesica resembled those of ocellatus 

 rather than those of populi, a condition usual in male 

 hybrids, in some of which no cornuti at all are present. 



The cingula was present only on the right side, and ended 

 abruptly in the mid-line. On the left side there was a thin, 

 rounded piece of chitin external to the ovipositor, of the 

 nature of which I am uncertain. 



The ostium bursae was very small, and the bursa itself 

 small and ill-formed. The rod of the ninth segment was 

 normal. 



The hybrid showed a perfectly halved condition of the 

 external genitalia without reduplication or defect, and it 

 is interesting that, although in the female hybrid male 

 external organs are always found usually in the form of 

 a coarse mosaic, none occur on the female half of this 

 gynandromorph. 



A comparison between the diagrams of the genitalia of 

 the gynandromorphs, which are drawn partly as trans- 

 parencies, with those of the genitalia of normal male and 

 female populi, will make it easy to understand the exact 

 degree of departure from the normal which the various 

 structures in the gynandromorphs exhibit. 



These three gynandromorphs, to my mind, are a further 

 proof that the same underlying cause can produce true 

 lateral genetic hermaphrodites, halved or lateral gynan- 

 dromorphs with one or more gonads of one sex only, or 

 without gonads of either sex, but with external structures 

 of both sexes (primary somatic hermaphrodites). 



The differences appear to me to be due to a failure of 

 part of the genital tract to develop, a failure which is 

 specially liable to affect the sexual gland itself. 



With regard to the external genital organs, the ideal 

 condition would be that in which exactly half the organs 

 of each sex would be present. This cannot occur except 

 in the case of the paired organs, such as the ovipositor 

 and directing-rod, the rod of the ninth segment in the 



