324 BEITISH BUTTERFLIES. 



It would have been easy to have assumed it to have been a blue 

 aberration of coridon, such as occurs racially in Spain and Asia 

 Minor, but the metallic lustre of the scales, and the ensemble of 

 the specimen led us to exhibit it at the meeting of the Ent. Soc. 

 of London, April 11th, 1894, as a hybrid $ of coridon xbellarg us. 

 The second specimen of this form that we saw was one almost the 

 counterpart of our own, exhibited by Dadd at the meeting of the 

 Ent. Soc. of London, October 21st, 1908, and noted (Proc. Ent. Soc. 

 Loud., 1908, p. lxiii) as a hybrid cory don xbellarg us, captured at 

 Airolo, June, 1907, flying with bellargus, which was very common in 

 the locality at the time it was captured. The next doubt that occurred 

 to our mind arose from the statement of Keynes (Ent. Piec, xx., p. 

 178) that, on June 25th, 1907, he captured in the Vallee du Lys 

 "two fine specimens of Polyommatus corydon var. corydonius, a variety" 

 which he had " not seen previously recorded from the French 

 Pyrenees ; the colour of these specimens is quite different from the 

 type, approaching that of bellargus, though the underside is typically 

 corydon; at first, indeed, we took it for a variety of P. bellargus which 

 was common everywhere : there was not a single specimen of corydon 

 (type) to be seen here, nor did we meet with it elsewhere in the 

 Pyrenees." Light broke on the subject when we were critically over- 

 hauling the material in the British Museum coll. Here, a specimen 

 labelled " Shar Deresy, Leech coll." was observed, exactly characteristic 

 of the specimens already noted, and as entirely different from the local 

 form of coridon, which is here of a pale lavender colour, as it is from 

 thetis (bellargus), which is brilliantly typical. Then, at the head of a 

 long series of specimens labelled polonus, was a specimen strikingly 

 different from all the others in the series, the counterpart of the just- 

 described examples, the same silvery or metallic bellargus blue, and bearing 

 this illuminating legend in Zeller's handwriting " Polonus, * S.E.Z.,' 

 '45, 351. Corydonius, H.-Sch. Zell. coll.," i.e., it was Zeller's type 

 polonus. Here history repeats itself, for, turning to Zeller's original 

 account (Stett. Ent. Zeit., 1845, p. 351), we read that he discovered in 

 Loew's collection, made in Posen, two strange-looking " blues," that 

 Loew kept one and gave him the other (the one now in the British 

 Museum coll.), that after three years Loew failed to find another, that 

 then he received a figure of another exactly similar example taken near 

 Frankfort-on-Main, and supposed by the captor and Metzner to be a 

 variety of corydon, an opinion which, however, Zeller says he could 

 not endorse, and he then describes it as polonus, noting it as " midway 

 between adonis and corydon, and were it not for the fact that three 

 quite similarly-coloured and marked examples on the upperside are 

 known to me, I might be pardoned for thinking that it is a hybrid 

 having on the upperside a ground colour combining the blue of both 

 species, but with the marginal markings of corydon, whilst on the 

 underside the colouring and marking is that of adonis." Zeller then 

 gives an excellent comparative description of polonus and the two 

 parent species, which, in the light of our present ignorance, is really 

 very remarkable. Herrich-Schaffer then figured (Sys. Bvarb., i., pi. 

 xci., figs. 432-3) without any description, an insect under Zeller's 

 name, polona, but in the supp. p. 27, says that the figure was made from 

 a $ received from Zeller (so that, apparently, Zeller's description 

 and Herrich-Schaffer's figure refer to the same example). Herrich- 



