BITHYS QUERCUS. 235 



[N.B. — All other references mentioned under the generic synonymy (anted, 

 pp. 230-231) are referable to quercus.'] 



Original description. — Papilio Plebeius quercus, alis subcaudatis, 

 supra cagruleis, subtus cinereis linea alba, puncto ani gemino fulvo. 

 Pet., "Gaz.," t. 11, f. 9. Ray, "Ins.," 129, no. 8. Alb., "Ins.," 

 t. 54, f. a. b. Roes., "Ins.," i., Pap. 2, t. 9. Wilk., "Pap.," 61, 

 t. 1, a. 1. Habitat in Quercu. Descr. : A\se omnes supra fusca? disco 

 caerulescente. Subtus omnes canescentes ; linea transversa repanda 

 alba ; posterius caudatse et ante caudam ocello gemino fulvo : pupilla 

 nigra (Linne, Sys. Nat., 10th ed., p. 482). 



Imago. — 31mm. -37mm. $ . All the wings of a deep purple, ex- 

 tending to the somewhat narrow, marginal, black border; the costa of the 

 hind wings also black; the outer margin of hindwings slightly crenulate ; 

 the caudal appendages white-tipped ; fringes of all wings greyish-white. 

 ? . Brownish-black, the forewings with a double violet patch, the 

 upper portion filling up discoidal cell, the lower portion in the space 

 beneath extending towards the anal angle ; the hindwings wholly 

 black-brown, rather paler than forewings ; fringes rather whiter than 

 in $ . Underside of both sexes grey, with a well-developed white line, 

 edged internally with dark grey, crossing all the wings ; a rather dark 

 grey antemarginal band, edged on either side with paler, darker 

 towards the anal angle of forewings, and containing an orange- 

 coloured, ocellated (black-centred) spot in hindwing, and orange anal 

 patch, edged inferiorly with black, at anal angle of hindwings ; 

 discoidal lunule well marked in all wings. 



Sexual dimorphism. — There appears to be some little difference in 

 the outline of the forewings in the sexes, those of the female rather 

 shorter and squarer than those of the male. The colour-difference in 

 the sexes is most marked, that of the male being purple, and extended 

 all over the wings, except the outer-marginal band, which is black ; 

 in the female the colour is brighter, violet rather than purple, and 

 limited to the discoidal cell and the area between the nervures, 

 although it sometimes spreads into the cell above. The examples in 

 the British Museum collection suggest that the $ s are rather larger 

 than the 2 s — the smallest $ being 35mm., the largest 40mm. ; the 

 smallest ? 28mm., the largest 37mm. 



Gynandromorphs. — The following are the only records we have 

 of gynandromorphic examples ; 



1. Right side <? , left side ? . Sold with the "Stevens" collection, March 

 27th, 1900. £3 15s. (Entom., xxxiii., p. 157). This example was figured by Mosley, 

 nius. Yars. Brit. Lep., Thecla pi. i., fig. 4 (1880). 



2. Left side c? , right side ? . Ground colour of all the wings that of the c? 

 sex ; all the wings also have the dark S hindmarginal band ; the right fore wing 

 shows in addition the purple ? patch, but the lower lobe of the patch does not run 

 even half across the wing. The abdomen appears rather stout. Bred by Junkel, 

 June 26th, 1902, from a larva taken near Lauterbach, near Crirnmitschau [Iris, 

 xviii., p. 26, pi. i., fig. 6). 



Colour of Bithys quercus. — The very slight prominence of the 

 teeth, and the general flatness of the scales in the iridescent glossy 

 areas, would suggest that this flatness, by scattering less the superficially 

 reflected light and reflecting it more in mass, gives this species its glossy 

 appearance. All the dark brown of this insect seems to be certainly 

 due to pigment-granules in the scales, but I also notice that the more 

 superficial scales which give the purple colour (undoubtedly by dis- 

 persion of light) are also coloured pale yellow or yellowish-brown. Is 



