GENERIC CHARACTERS OF THE LYC.ENIDS. 101 



On the generic characters of the ancillary appendages of the 

 Plebeiid section of the Lycaenids [nith plate). 



By T. A. CHAPMAN, M.D., F.E.S. 



In A Xatioal Histoii/ of the Britifih Lepldoptera, vol. x., pp. 155 

 H xeq., are some remarks on the male appendages of Plebeiids. I have 

 since arrived at some conclusions of importance in this matter, 

 although they leave many points still to be co-ordinated. 



The form of the clasps and dorsal processes define the group very 

 distinctly from any other, but are also very slightly different in 

 different species, yet almost always sufficiently to afford specific 

 characters. But their failure to afford characters to define genera is 

 remarkable, in view of their affording such good tribal and specific 

 cliaracters. This failure is noted specially {loc. cit.) in the case of the 

 ^enns I'iebeiits. In regard to the other genera there referred to, the 

 cbaracters are also rather too indefinite, so much so that they made 

 me very sceptical as to the value of the genera accepted by Mr. Tutt, 

 especially as he gives no definitions of them except by saying what 

 species he puts in them. Nevertheless, besides recognising the 

 groupings so made to have each a somewhat distinctive facies, I had 

 much confidence in Mr. Tutt's instinctive power of recognising generic 

 groups in a case like this. It is, therefore, with some pleasure that I 

 find a character of the appendages that defines several of these genera 

 more exactly than any other yet suggested, and does so fairly in accord 

 with Mr. Tutt's divisions. The jedoeagus affords a ver}^ distinct form 

 in several of the genera. Especially, for example, it separates ^7r/rt(/<'.s- 

 (eunilon) from PolyonDiicitiis {icanis), two genera for which no differ- 

 entiating characters had been proposed. 



Aijriaden has perhaps the most easily recognised form of fedoeagus, 

 well seen in vol. x., pi. xxi., fig. 4, a straight shaft, with a contracted 

 neck at the base, but most characteristically a bulbous swelling at the 

 top. Here it is necessary to define a point in the connections of the 

 iedoeagus ; this is its attachment to the floor of the genital cavity, 

 through which it passes. The aedoeagus has this membrane attached 

 to it at a particular zone or circle. In Af/riades this zone is on the 

 bulbous swelling near its lower margin, and the portion of the organ 

 above the membrane is merely the upper part of the bulb and a small 

 projection beyond. Poli/oiiuiiatKs [icants) agrees with Aifriodes in 

 having a comparatively small portion beyond the zone of attachment, 

 but this portion is in fact a shade longer, and differs iji toto, in taper- 

 ing from the zone onwards, and having no trace of a bulb. This 

 portion is also of much slighter texture than the bulb in Aijriades, 

 which is a dense and highly chitinised structure. 



Aricia {astrarc/te) has a highly characteristic structure, very different 

 from the two we have been considering. In this, the portion beyond 

 the zone is much prolonged. It may be noted that, throughout the 

 Plebeiids, the portion of the fedoeagus within the zone does not vary 

 much in length in the different species, generally about 0-65mm. in 

 length, it varies in different species to 0'5omm. to 0-8mm., rarely 

 outside these limits. The portion beyond the zone varies much more 

 widely — in Afiriades about 0'22mm., in Aricia {astrardic) it is nearly 

 O'Bmm., longer than the basal portion. It tapers gradually to a point, 

 and appears to have a long lateral opening instead of the nearly 

 May 15th, 1910. 



