ARICIA MEEON. 241 



are those which are peculiar to the northern portion of the British 

 Isles, viz., salmacis which occurs in the north of England, and 

 particularly on the coast of the County of Durham, and artaxersees, 

 which is the usual form over the Scotch border ; the latter being both the 

 more distinct, and the more conspicuous. Both races, but especially 

 salmacis, exhibit several aberrations, a number of those of the latter 

 race being of more or less frequent occurrence. 



For many years after artaxerxes was described by Fabricius, in 

 1793, it was regarded as unquestionably a distinct species, both by 

 British and foreign entomologists ; Lewin, Haworth, Donovan, Leach, 

 Miss Jermyn, Samouelle, Stephens, Wood, Westwood, Doubleday and 

 Stainton among the former, and Godart, Meigen, Boisduval, Treitschke, 

 Freyer, Heydenreich, Gerhard and Lederer among the latter, all treat 

 it as such, though, in the time of the later writers mentioned above, 

 the controversy on the subject, which had been carried on in a desultory 

 way for some time, was about to reach an acute stage. In 1831 

 Stephens -considered that he had detected a third species among the 

 Durham examples sent to him by Wailes, which he described in the 

 3rd vol. of his Illustrations, and named salmacis. This, however, being 

 intermediate between the medon of the south and the artaxerxes of 

 Scotland, proved to be the link through which the identity of the three 

 so-called species was eventually determined. 



The first suggestion of this identity was due to Edward Newman, 

 who wrote in 1834, in the Entomological Magazine, vol. ii., p. 575, 

 as follows : — 



" From examining specimens of Polyommatus agestis from different 

 localities, I have arrived at a conclusion which will not, I fear, be 

 coincided with by many of our Lepidopterists. On the South Downs 

 of Sussex and Kent, agestis assumes what may be called its typical 

 form. I have taken it at Kamsgate, Dover, Hythe, Hastings, Rye, 

 Brighton, Worthing, Little Hampton, Chichester, Portsmouth, Isle of 

 Wight, Dorsetshire, Somersetshire ; and throughout this range it is 

 very similar : then, going upwards, I have met with it at Worcester, 

 Birmingham, Shrewsbury ; and here an evident change has taken 

 place, the band of rust-coloured spots has become less bright ; at 

 Manchester these spots have left the upperwing almost entirely ; at 

 Castle Eden Dean they are scarcely to be traced, and a black spot in 

 the centre of the upperwing becomes fringed with white; the butterfly 

 then changes its name to salmacis. We proceed further northwards, 

 and the black pupil leaves the eyes on the underside, until at Edinburgh 

 they are quite gone ; it is then called artaxerxes. The conclusion I 

 arrive at is this, that agestis, salmacis, and artaxerxes are but one 

 species." 



The point thus raised did not, at the time, lead to any great 

 amount of controversy, nor, indeed, to anything more than a few 

 passing surmises, and entomologists seem to have been satisfied that 

 medon and artaxerxes, at any rate, were separate species until the 

 discovery by Professor Zeller that the larvae were indistinguishable. 

 The usual food-plant of wedon being Erodium cicutariuvi while that of 

 artaxerxes was found to be Helianthemum vulgare, caused Dr. Lowe to 

 lay it down, in a paper read in 1857 before the Royal Society of 

 Edinburgh, as practically settled, that the two were distinct species, 

 while he regarded salmacis as a variety of medon, rather than of 



