1881.] PROF. J. O. WESTWOOD ON INDIAN BUTTERFLIES, 479 



6. Observations ou two Species of ludian Butterflies {Pa- 

 pilio castor and P. poNiix) . By J. O. Westwood, M.A., 

 F.L.S., &c. 



[Receiyed February 12, 1881.] 

 (Plates XLIV., XLY.) 



In the 80tli plate of my 'Arcana Entomologica,' published 1st 

 September, 1844, I represented, under the names of Papillo castor 

 and P. j)ollux, two theretofore unfigured and undescrlbed Butterflies, 

 which I regarded as distinct species, sent from Assam and Sylhet by 

 the Rev. J. Staniforth and Major F. Jenlcins. 



The first of these two Butterflies, P. castor, of which males only 

 had been sent, is of a dark brown or nearly black colour on the 

 upper surface of the wings, the anterior pair having no other mark- 

 ing on this side than very small white marks on the outer margin 

 between the extremities of the longitudinal veins, growing gradually 

 smaller and even obsolete from the middle of this margin to the 

 apex of the wing ; on the upper surface of the hind wings there is a 

 large, very pale yellowish-white patch near the outer angle, divided by 

 the longitudinal veins into four spots (Plate XLIV. fig. \, upperside 

 of the hind wing). On the underside the fore wings have a very 

 small white spot at the extremity of the discoidal cell ; the minute 

 white marginal spots described above are present, and are preceded 

 by a row of very minute white spots close to the outer margin of the 

 wing, and which diminish in size and l)ecome obsolete towards the 

 apex in the same manner as the marginal dots. The hind wings on 

 the underside have the four large spots towards the outer angle of a 

 diminished size, the first and fourth being very small. The small white 

 marginal incisures are preceded by a submarginal row of verv small 

 white spots, of which the middle ones are almost obliterated, whilst 

 the one at the anal angle is duplicated (Plate XLIV. fig. 2 represents 

 the underside of the hind wing). In some specimens the submar- 

 ginal row of white spots on the hind wings are more decided and 

 larger than in others. It is to be added that the hind wings are 

 elongate-ovate, produced more decidedly at the extremity of the third 

 branch of the median vein, which is, in the regularly tailed species, 

 developed into the spatulate tail. The head and neck are dotted 

 with white ; and there are two rows of white dots on the upper sur- 

 face of the abdominal segments. 



These male insects vary considerably in size : the expanse of the 

 more normal individuals is 4^ inches ; but specimens before me vary 

 from 3^ to 4f inches. Plate XLIV. fig. 3 represents the upper- 

 side of the hind wing of the smallest individual, of the natural size ; 

 the large white discoidal spot is comparatively larger than usual; 

 and there are very slight traces to be observed of a row of submar- 

 ginal white spots represented by a few scales. It is from Sylhet. 



The second of my supposed species (P. poUux) was figured from 



