1881.] PROF. J. O. -WESTWOOD ON INDIAN BUTTERFLIES. 481 



By the late Mr. G. R. Gray (Catal. Lepid. Ins. Brit. Mus. 4to, 

 1852, p. 21) Papilio castor (sp. 93) is thus given : — 



" cS . Papilio castor, Westw. Ann. Nat. Hist. ix. (1842), p. 37; 

 id. Arc. Ent. pi. 80. figs. 1, 2 [2, 2*] ; E. Doubl. Gen. of D. Lep. 

 pp. 12,72. 



"$. Papilio pollux, Westw. Ann. Nat. Hist. ix. (1842), p. 37; 

 id. Arc. Ent. pi. 90 [80], fig. 1 ; E. Doubl. Gen. D. Lep. pp. 21, 

 264. 



"Papilio xenocles, pt., Erichs. Wiegm. Arch. f. Naturg. 1843, ii. 

 p. 248. 



" In collection (Brit, Mus.) from Northern India. 

 ' " Variety a. d . Much less in size, and ornamented by small 

 lunules along the outer margin, especially below the white space of 

 the secondary wings. In collection (Brit. Mus.) from Northern 

 India." 



In Mr. Hewitson's cabinet- (bequeathed by him to the British 

 Museum) the two species stood under the name of P. castor; and as 

 such they appear in the printed catalogue of his collection (p. 3), 

 without any reference to P. pollux. 



Felder (Sp. Lepid., in Verb. Zool.-Botan. Gesellsch. Vienna, 

 1864, p. 320) gives as a separate section C, no. 244, P. castor, Westw., 

 with P. pollux &s its female, followed by no. 414, P. phestus, Gue'rin. 



Kirby (Syn. Cat. Diurn, Lep. p. 546) gives P. castor as the male, 

 and P. pollux as the female, of one species, " teste Athinson." 



M. Charles Oberthiir (Etudes Entomol. part iv. " Catal. rais. des 

 Papilionidse de la Collection de Ch. Oberthiir," p. 49, December 

 18/9) gives as his species " 8a, S castor, Westw. Arc. Ent. pi. 80. 

 fig. 2; 2 polhuv, Westw. Arc. Ent. pi. 80. fig. 1 ;" but in his Ap- 

 pendix (p. 1 14) he states : — "L'honorable M. Westwood m'a informe 

 qu'il etait convaincu que castor et pollux etaient non plus I'un le c? et 

 I'autre la $ d'une meme espece, mais bien deux especes difterentes 

 dont il connaissait pour chacun les deux sexes'. J'ai reru moi-meme 

 till SikJcim la $ castor semblable au S ." Here we have a distinct 

 statement that the female of P. castor is similar to the male. 



The figures which accompany the present memoir have been drawn 

 with the view of showing the amount of variation undergone in the 

 shape of the wing and in the markings of these Butterflies, and bear- 

 ing on the question of their sexual modification and identity. 



In Plate XLIV. fig. 1 the upperside of the hind wing of the ordi- 

 nary form of the male of P. castor is shown, its form being compared 

 with the outline of the hind wing of the female P. pollux. In this 

 figure the rudimentary tailed wing of the former (*), and the 

 rounded wing of the latter (a b), are unmistakably apparent. In 

 figure 2 the underside of the same wing of P. castor is delineated, 

 showing the series of small submarginal spots, some of which are 

 almost obsolete. Figure 3 represents the upperside of the hind wing 

 of the smallest specimen which I have yet seen of P, castor, and 



' This part of M. Oberthiir's statement is erroneous, as I stated to him 

 that I possessed the two sexes of P. pollux, but onlj- males of P. castor, regarding 

 at that time the Butterfly figured in Plate XLV. fig. 1, as the male of P.pollux. 



