146 J. Wood-Mason — On a new Papilio from South India, [No. 3, 



in size as to be barely visible, being, in fact, mere specks confined to the 

 fringe ; the hind-wing has lost all but the incisural specks (which are 

 similarly confined to the fringe) and the first three or four spots of the 

 diseal series, which together form a large and conspicuous cream-coloured 

 blotch divided by the veins : P. Castor may, in fact, be described as a rich 

 dead-black insect with a conspicuous cream-coloured blotch near the outer 

 angle of each hind-wing. 



In P. Castor, then, the sexes are, as regards colour and markings, as 

 strongly differentiated from one anotlier as in any species with which 

 I am acquainted ; they also differ to some extent in form, the male 

 having the fore-wing narrower, with the external margin obviously emar- 

 ginate, and the hind-wing also narrower and produced, with the same margin 

 more deeply incised and lobed than in the female, both pairs of whose wings 

 in form more or less closely* resemble those of both sexes in the other two 

 species. 



In P. Mahadeva, the sexes are also tolerably well, though not so con- 

 spicuously, differentiated in point of colour and markings as in P. Castor, 

 but not at all in form, the wings being of the same shape ia both sexes. 



In P. Dravidarum, the sexes agree perfectly both in form of wings and 

 markings, differing very slightly in colour only ; so that but little sexual 

 differentiation has here taken place. 



The female of P. Dravidarum is scarcely distinguishable, as far as one 

 can tell from a description alone, from that of P. Ulahadeva, the only 

 differences that I can make out being that in the latter " the fore-wings 

 have very small and less distinct sub-marginal white spots, and no spot at 

 the end of the cell." From that of P. Castor, however, it is readily distin- 

 guished by having, as I have already pointed out, the discal markings of the 

 hind-wing in the form of a transverse band of short lanceolate spots. 



At the meeting of the Linnfean Society of London held on the 18th 

 March last, a paper by Prof. Westwood, on a supposed polymorphic butter- 

 fly from India, was read. In this memoir the following conclusions are 

 said {vide abstract in 'Nature' Vol. XXI, p. 531, April 1st, 1880) to have 

 been arrived at by the author : — (1) " That Papilio Castor is the male of a 

 species whose females have not yet been discovered ; (2) that the typical 

 P. Pollux are females of which the males with rounded hind-wings having 

 a diffused row of markings has yet to be discovered ; and (3) that the 

 coloured figures given by the author represent the two sexes of a dimorphic 

 form of the species." 



* The females present an inconspicuous dimorphism, some having retained the 

 primordial form of hind-wing, while others have the outer margin of this wing toothed 

 as in the male {vid« infra). 



