68 ^[iscellaneoiis. 



having the third brauch of the median vein not produced, and the 

 outer margin of the wing consequently " rounder," being in fact 

 typical P. Pollux ; and four (tvro from Silhet* and two from 

 Sikkim t) having that veinlet produced into a small tooth, as in the 

 male. I consider that these two ditFerent forms are both females 

 of P. Castor, and that the slight differences they present are ex- 

 plained on the supposition, warranted by numerous analogous facts 

 in nature, that the secondary sexual characters acquired by the 

 male have been partially transmitted to some females, but not to 

 others (P. Pollux), which have retained the primordial rounded 

 form of wing. 



The fact that the discoidal markings of the hind wing in the two 

 Silhet females w^th toothed wings are lighter and more distinctly 

 cream-coloured than in any of the females with rounded wings, 

 that the malformed specimen from the same locality (which cer- 

 tainly belongs to the foi'm with toothed hind wings) has these 

 markings in the fourth, fifth, and sixth interspaces (those, that is 

 to say, corresponding to the ones forming the principal part of the 

 blotch in the male) of almost as rich and pure a colour as in that 

 sex, and that one of the two former has the spot at the end of the 

 cell and the submarginal markings of both fore wings obsolete and 

 is thus stiU further approximated to the male, do certainly seem to 

 me to tell rather for than against the above supposition. 



The Eehnus group of Papilios, to which Pajnlio Castor and its 

 allies unquestionably belong, taken as a whole, presents us with a 

 remarkable series of gradations in the amount of difference between 

 the sexes, comprising, as it does : — one species (P. Dravidarmn) in 

 •which the sexes closely resemble one another in the form of the 

 wings and in colour and markings, and there is only an incipient 



* There is a third specimen from SUhet in the collection, taken at the 

 same time and place as the other two ; but it unfortunately has the bind 

 wings svmmetrically malformed at their outer margins, the third lobule 

 on each side being short and angidated, and the fourth being somewhat 

 longer than usual and also angulated. This malformation is interesting 

 as showing in the same specimen the instability of this character, the 

 strono- tendency to the assumption of the male form of wing exhibited in 

 the lengthening of the lobule next in order, and the unmistakable " re- 

 version " to the rounded form of wing in the suppression of the rudi- 

 mentary tail. 



It should he mentioned that a gynandromorphous example of the form 

 of female described by Prof. West wood as P. Pollux has been figured 

 and described as P. Castor by G. Semper in Wien. entom. Monatschr. 

 1863, Band vii. p. 281, Taf. 19. In this specimen both the wings of the 

 left side are truly female ; but on the opposite side the posterior portion 

 of the fore wing from the first discoidal veinlet to the inner margin on 

 the upperside only, and the anterior portion of the hind wing from the 

 costal margin to "the second branch of the subcostal on both sides, ex- 

 hibit the mascuUae livery, not unmingled with female characters (conf. 

 Westwood in Thes. Ent. Oxon. p. 187). 



t The two Sikkim specimens have the tooth less developed and the 

 discal markings of the hind wings exactlv like those of the other form 

 (P. PoUux). 



