xvr 



the extension of the dark pigment began. In a great many Lycaenidae, 

 especially in the numerous species which Snellen includes in his genus Lycaena, 

 it can be clearly seen that, as a rule, the females are more lightly and whitishly 

 coloured, especially on the upperside, than the males ; and that in connection 

 with this, the structural colours, which are found so frequently in the Lycaenidae, 

 when they are present in the male, disappear in the female or at least become 

 much fainter. We find this even amongst the Arhopala species, although 

 in this case the females are also very darkly coloured, and the above mentioned 

 extension of dark pigment along the costal margin, the outer margin and the 

 apex of the upperside of the forewings is very common in the female. This 

 cannot be strictly speaking sexual, as it occurs in the cf of Lycaena Bochus 

 (PI. XXI^) Cram., L. Ouadriplaga Sn. (PL XXII 72a) and L. Marginata 

 de Nic (PI. XXII 73^), for instance, but it appears so often in the $, that it 

 is generally acknowledged as a female characteristic, and is even often erroneously 

 regarded as a secondary sexual phenomenon. Why should this be so ? Observation 

 shows that the same fading process of colour-evolution which shows itself in all 

 Rhopalocera, although in many species it is already accomplished, or is invisible 

 on account of the accumulation of dark pigment, also governs the Lycaenidae, 

 and therefore originally, when the evolutionary fading took place, must have 

 played an important part in it. Little of the original red colour now remains ; 

 certain species, however, have stopped when more or less advanced is this stage of 

 colour evolution. This is so amongst the Pleridae, with Pieris Nero F. and 

 related races. There are also some amongst the Lycaenidae. In Curetis 

 Insularis Horsf cf (Plate XXIV i20ad) the original red colour is still preserved 

 upon the upperside, although the underside has become completely white, 

 but in the 9 this red has been partially crowded out by the spreading of the 

 dark pigment, and is further perceptibly faded; in this species therefore the 

 fading process is on the upperside still progressing, and is most advanced in 

 the female. In other Lycaenidae, where the original red still remains, as in 

 Deudorix Jarbas F. (PI. XXV 133,06) it is very distinct on the upperside 

 of the male, but in the female it is considerably faded. Judging by these 

 cases, it becomes very probable that in other cases, where the colour of the 

 upperside of the 9 of one species is conspicuously lighter than that of the cf , 

 it is the consequence of the same process of fading, which has proceeded further 

 in the 9 than in the cf . But very soon after the fading had begun an extension 

 of the black pigment over it seems to have commenced as may be seen even 

 in the 9 of the above mentioned Curetis Insularis Horsf (PL XXIV 120^) which 

 is still so little faded — causing a darkening of the upper surface, where more- 

 over the even mentioned concentration in the apex, costal margin, and the 



