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VI. On the Pairing of the Plebeiid Blue Butterflies (Lycae- 

 ninae, tribe Plebeiidi). Bv T. A. Chapman, M.D., 

 F.Z.S. 



[Read March 1st, 1916.] 



Plates XVIII-LXII. 



In the following notes I propose to describe some specialisa- 

 tions of both the male and female appendages in the tribe 

 Plebeiidi of the " Blues " (Lycaeninae). 



Much has been done* in the description of the male 

 appendages of the Lepidoptera, both from a morphological 

 and a systematic point of view, though not perhaps much 

 as compared with what remains to do. The female 

 appendages have been less elucidated, and the precise 

 correlation of the male and female appendages has barely 

 been dealt with. 



My observations refer to the latter aspect of the subject 

 in a small tribe of the " Blue " butterflies, in which the 

 specialisations seem at first sight quite paradoxical when 

 compared with what is usual in the rest of the order. A 

 few years ago on comparing notes with my friend the 

 Rev. C. R. N. Burrows, it appeared that he had noted that 

 there was something unusual in the pairing of these butter- 

 flies, and it is very probable that, like us, others were, 

 broadly speaking, cognisant of this circumstance; but I 

 have not met with any published account of the facts 

 either generally or in detail. 



It may be arguing in a circle, but I incline to define the 

 Plebeiidi, as those butterflies that possess this particular 

 specialisation, and to assert that it does not exist outside 

 the tribe. This, however, will not seem so irrational, in 

 view of the fact that, with small specific variations, the 

 structures throughout the tribe are very uniform, and that 

 outside it there is a considerable gap between it and the 

 nearest approach to it amongst related tribes. 



The " Blue " butterflies (the sub-family Lycaeninae) 

 comprise a number of tribes ; the one we are interested in, 

 the Plebeiidi, is especially a Palaearctic (and Nearctic) one. 

 For example, of the eleven Blues accredited to our British 



TRANS. ENT. SOC. LOND. 1916. — PART I. (AUG.) 



