402 SEXUAL SELECTION. Part II. 



to colour there is no difficulty, as any number of highly 

 variable Lepicloptera could be named. One good in- 

 stance will suffice. Mr. Bates shewed me a whole series 

 of specimens of Pcqoilio sesostris and children^ ; in the 

 latter the males varied much in the extent of the beau- 

 tifully enamelled green patch on the fore-wings, and 

 in the size of the white mark, as well as of the splendid 

 crimson stripe on the hind-wings ; so that there was 

 a great contrast between the most and least gaudy 

 males. The male of Pajnlio sesostris, though a beautiful 

 insect, is much less so than P. chilclrense. It likewise 

 varies a little in the size of the green patch on the fore- 

 wings, and in the occasional appearance of a small 

 crimson stripe on the hind- wings, borrowed, as it would 

 seem, from its own female ; for the females of this and 

 of many other species in the ^neas group possess this 

 crimson stripe. Hence between the brightest specimens 

 of P. sesostris and the least bright of P. children^, there 

 was but a small interval ; and it was evident that as far 

 as mere variability is concerned, there would be no 

 difficulty in permanently increasing by means of selec- 

 tion the beauty of either species. The variability is 

 here almost confined to the male sex ; but Mr. Wallace 

 and Mr. Bates have shewn 18 that the females of some 

 other species are extremely variable, the males being 

 nearly constant. As I have before mentioned the Ghost 

 Moth (Hepialus humuli) as one of the best instances in 

 Britain of a difference in colour between the sexes of 

 moths, it may be worth adding 19 that in the Shetland 



18 Wallace on the Papilionidae of the Malayan Region, in ' Transact. 

 Linn. Soc.' vol. xxv. 1865, p. 8, 36. A striking case of a rare variety, 

 strictly intermediate between two other well-marked female varieties, 

 is given by Mr. Wallace. See also Mr. Bates, in ' Proc. Entomolog. 

 Soc.' Nov. 19th, 1866, p. xl. 



19 Mr. R. MacLacblan, ' Transact. Ent. Soc' vol. ii. part 6th, 3rd 

 series, 1866, p. 459. 



