DIMORPHA VERSICOLORA. 239 



domen, the ? side is somewhat broadened and less haired ; . . . . the hind 

 margin of the amis is rather truncate as in a normal <? ; the ? genitalia are con- 

 cealed under a dense tuft of hairs ; although it appears from the marked 

 development of the <? genital organs that this specimen is principally male, yet 

 the tendency towards the 3 form decreases in the wings. Were the example a 

 normal male one would call it a giant, the ? wings being of normal size, and 

 the $ wings but little less. For the specimen I have to thank a highly-esteemed 

 friend in Russia (Riihl, Societas Entom., vi., p. 98). 



/c. Halved. Left completely ? , right <? . Left side of wings and left 

 antenna ? ; right side of wings and right antenna 3 . Body divided into two 

 halves following the two sexes, thus differing strikingly the one side from the 

 other in build, colour, and clothing ( <? side with longer hairs). In the Museum 

 at Altenburg (Schultz, Illus. Ze its. fur Ent., in., p. 184). 



Variation. — The species does not appear to be subject to much 

 variation. In size, as already pointed out, males vary from 49mm. 

 — 67mm. and females from 62'5iiim. — 87-5111111., whilst in colour the 

 males sometimes approach the female, and the females the male, 

 coloration. Barrett notes (Lefi. Brit., hi., p. 52) that "variation appears 

 to exist only in the intensity of colour and of clouding, but in some 

 individuals the darker clouding is almost absent. In the Doubleday 

 collection is a very dark male, and, in that of Bond, a female with 

 the hindwings nearly white. As a rule, specimens from Scotland are 

 of deeper, richer colour than those from the south of England." In 

 the British Museum collection, one $ (from the Frey coll.) has the 

 white on the forewings very strongly developed and the brown is also 

 deepened and intensified, producing a much more strongly marked 

 example than the majority of the British Museum specimens ; one 

 may summarise the differences in the latter as being confined 

 to the depth and extent of the brown areas as opposed to the 

 white. Frings records (Soc. Ent., xiii., p. 129) a very dark marked 

 2 aberration with pale red-brown hindwings from Russia. One 

 suspects that the wing-markings are very primitive, since those of the 

 forewings are practically repeated on the hindwings. In our British 

 series, there is much difference in the intensity of the markings, the 

 depth of the ground-colour, and the quantity of pale shading, more 

 especially in the $ s. In some specimens, too, the discal V-shaped 

 mark is reduced to a mere point, or it may be altogether absent. 

 The silvery-white apical spots vary considerably in size, they are 

 also, in some specimens, united, in others very distinctly separated. 

 In the hindwings of the $ s the markings are sometimes almost 

 obsolete, and the wings practically unicolorous, whilst the normally 

 white apical spots are frequently absorbed in the ground-colour. In 

 the hindwings of the females the presence of a brown line within and 

 crossing the angle made by the median line and a tendency to the 

 development of dark spots on the outer margin are the most 

 noteworthy features. There is insufficient variation to form any 

 really useful tabulation ; the only attempt we have made at grouping 

 the males may be noted as : 



1. a. Forewings pale orange-brown, with distinct transverse lines, the pale 

 margins not pure white ; the median area paler and greyer ; the hindwings 

 orange-brown with distinct markings, and whitish apical spots=rab. pallida, n. ab. 

 (3. Similar, but with ill-developed or obsolete markings on hindwings=ab. pallida- 

 obsoleta, n. ab. 



2. a. Forewings bright orange-brown, rather darker than I ; the shading 

 between the elbowed and subterminal lines still darker, and forming a better con- 

 trast. Hindwings orange, with distinct markings, apical spots ochreous rather 



