Butter files of Bulgaria. 191 



usually frequented ; but the white form was certainly more 

 abundant than the orange, though Mrs. Nicholl found this 

 was not the case in Bosnia, and in Austria the white 

 female occurs as a rare aberration only. My orange 

 female is very like that of licldreichi on the upper- 

 side, but can be distinguished by the brighter colour 

 below. HeldreicM, which has hitherto only been taken 

 on the highest peaks of Veluchi, Chelmos, and Par- 

 nassus in Greece, at 7000 — 8000 feet, and has been 

 treated as a var. of aurorina, seems to be more worthy 

 of specific rank than many other so-called species of 

 Colias. 



The fact is, that in this genus, as in many others, 

 wherever you find a butterfly restricted by geographical 

 or physical conditions to an isolated locality, it is com- 

 paratively easy to recognize and define its distinguishing 

 characters ; but when you find a species whose greater 

 powers of adaptation to varying conditions of food and 

 climate enable it to exist over a wide area, then it often 

 becomes impossible to define its local varieties. There 

 is no evident reason Avhy myrmidone should not extend 

 its range to Greece, and we do not yet know whether 

 Jieldrcichi may not occur in the Southern Rhodope or 

 Macedonia ; but from a geographical point of view it 

 would seem likely that heldreichi is more nearly allied 

 to myrmidone than to aurorina, from which it is separ- 

 ated by wide areas of sea. 



IG. Golias edusa, Fabr. 



Common up to about 5000 — GOOO feet, and a,lways dis- 

 tinguishable on the wing from myrmido7ie by its paler 

 colour. 



17. C. hyalc, L. 



Not seen in the mountains, but common in the plains 

 and at Slivno. 



18. Thecla ilicis, Esp. 



A few specimens were taken at about 4000 feet. 



19. T. quercus, L. 



Not seen in Rilo Dagh, but taken in the Balkans at 

 the end of July. 



