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XVI. Gynandromorphous Lepidoptera. By E. A. Cockayne. 

 M.A., D.M, F.R.C.P., F.E.S. 



Plates XCIII-CIV. 



[Read October 4th, 1916.] 



The rarity of gynandromorphous Lepidoptera and the 

 difficulty of obtaining them in a condition fit for dissection 

 has stood in the way of the examination of their internal 

 anatomy. The internal organs have been investigated 

 and described in about twenty perfectly or almost perfectly 

 halved examples. Eight of these in Amorpha populi I 

 figured and described in the Journal of Genetics. Six of 

 those previously described were also examples of gynan- 

 dromorphs of this species. Since these were published I 

 have dissected two more Amorpha populi and one Amorpha 

 hybridus Steph. (A. ocellatus $ x A. populi 9.). As in the 

 former examples the populi were from Newman's strain, 

 as was the female parent of the hybrid. The hybrid was 

 bred by Mr. Sydney Whicher, to whose generosity I am 

 indebted for the specimen. 



The first A. populi (R $, L 9) showed in all external 

 characters perfect halving, and the colour, dark grey, was 

 the same on both sides. On dissection it proved to have 

 on the right side a testis, vesicula seminalis, vas deferens, 

 glandula accessoria, ductus ejaculatorius and penis, and 

 on the left side an ovary with four follicles, oviduct, sper- 

 matheca or receptaculum seminis, cement gland, and bursa 

 copulatrix. It was, in fact, a true genetic hermaphrodite 

 without any reduplication of organs and with only one 

 defect, absence of the ductus bursae or seminis. The 

 external genitalia showed on the last segment a small 

 uncus continuous in the usual way with the tegumen and 

 cingula, and on the left a half ovipositor with its coarse 

 tactile hairs and directing-rod. Opposed to the uncus was 

 the gnathus, and between them lay the anus. The less 

 distal segments showed a similar halved arrangement of 

 male and female structures. There was a nearly perfect 

 right valve (14) and harpe (15) and a much smaller left 

 valve and harpe. Behind and between lay a normal ring- 



TRANS. ENT. SOC. LOND. 1916. — PARTS III, IV. (APRIL '17) 



