1880.] 



with Remarlcs on the Species allied thereto. 



147 



With regard to the last of these conclusions I cannot speak, because 

 neither the paintings nor the specimens in question are accessible to me ; 

 but, having spoken above as if the opposite sex of P. Castor were perfectly- 

 well-known to naturalists, while, according to Prof. Westwood, it is still 

 undiscovered, I ought perhaps to say a few words about the material on 

 which my remarks are based. 



Papilio Castor is restricted in its distribution to the slopes and valleys 

 of the hill-ranges of North Eastern India and to the parts of the plains in 

 immediate contiguity with them ; its place being taken elsewhere, as in 

 -Southern India, by the new species described in the preceding pages, and, 

 in Burmah, by P. Mahadeva. The Indian Museum possesses specimens 

 from the Southern slopes of the Khasi Hills (Silhet), from the Sikkim 

 Hills (Darjiling), Cherra Punji in the Khaoi Hills, and the Naga Hills ; 

 and three males were taken by Lieut. -Col. Godwin-Austen during the 

 Dafla Expedition ; in these last, in a large male from Cherra Punji, and in 

 two specimens of the same sex from the Naga Hills the upper surface is 

 dark brown of a much lighter tint than in nine males recently received 

 from Sikkim (2) and Silhet (7), which are all brown-black of so dark a shade 

 as to appear quite black except when a strong light falls upon them when 

 their colour appears brownish ; in fact, the brown of the former is to that of 

 the latter series of specimens what dark green is to the colour known as 

 " invisible-green." In the large Cherra Punji specimen, the short tooth, 

 or rudimentary tail, into which the third branch {d.^, pi. ix, fig. 1) of the 

 median vein of the hind-wing is usually produced, does not extend beyond the 

 line of the other lobes of the outer margin, and one of the three dwarfed 

 winter specimens* captured by Col. Austen approaches it in this respect ; 

 moreover, one of the Silhet specimens has this tooth smaller in one wing 

 than in the other, so that this, like secondary sexual characters in general, 

 is subject to variation. It is possibly to difference of station, but jjrobably 

 to long exposure to the vicissitudes of the Calcutta climate, and to the 

 applications of benzine and other noxious substances to which they were 

 subjected before I took over charge of the collection of Lepidoptera, that 

 these brown specimens owe their lighter coloration. However this may be, 

 it may confidently be asserted that it would be impossible for the most 

 inveterate species-maker to discover any character by which to separate 

 them as a distinct species or race from the fresh and consequently dark 

 Sikkim and Silhet specimens. So much for the males. 



Of the nine females in the collection referred by me to P. Castor, 

 seven being perfect can readily be divided into two sets according to the 

 form of the outer margin of the hind-wing — three (one from Assam, one 



• The insect figured by Westwood (Arcana Entom. vol. ii, pi. 80, fig. 2) seems to 

 have been a similarly dwarfed and faded individual. 



